Merge pull request #1508 from ludovic111/fix/st-wind-charge

🤖 Agent: merged after verify and CI parity passed, built merged with current main (st-default-2: server-thread gaps checked against vanilla, each with a lan_e2e check that fails before and passes after, host and guest, both modes; numbers in the PR body).

crates/horizon-client/Cargo.toml

@@ -87,3 +87,7 @@ rng-trace = ["horizon-core/rng-trace"]
 
 [lints]
 workspace = true
+
+[dev-dependencies]
+# Every WGSL shader translated as wgpu's DirectX 12 backend does (gfx.rs tests).
+naga = { version = "30.0.1", features = ["wgsl-in", "hlsl-out", "msl-out", "spv-out"] }

crates/horizon-client/src/game.rs

@@ -1817,6 +1817,16 @@ impl Game<'_> {
         self.stack_in_mut(self.held_slot())
     }
     /// The slot of the hand that acts: the selected one, or `OFFHAND_SLOT`.
+    /// `LivingEntity.canGlideUsing`: a glider in the chest slot that will
+    /// not break with its next point of wear.
+    fn glider_worn(&self) -> bool {
+        self.armor[1].as_ref().is_some_and(|s| {
+            self.res
+                .items()
+                .get(&s.item)
+                .is_some_and(|i| i.glider && (i.max_damage == 0 || s.damage + 1 < i.max_damage))
+        })
+    }
     fn held_slot(&self) -> usize {
         match self.hand {
             Hand::Main => self.selected,
@@ -1994,6 +2004,28 @@ impl Game<'_> {
         particle.scale(0.6);
         self.particles.push(particle);
     }
+    /// `Player.dropEquipment` for the player who died: unless keep_inventory
+    /// is on, `destroyVanishingCursedItems`, then `Inventory.dropAll` from
+    /// `at` (the eyes less 0.3): slots 0..36, armor feet to head (36..39),
+    /// the off hand (40), each thrown in a random direction.
+    fn drop_inventory(&mut self, at: [f64; 3]) {
+        if self.ui.rules.bool("keep_inventory") {
+            return;
+        }
+        let mut stacks: Vec<ItemStack> =
+            self.inventory.iter_mut().filter_map(Option::take).collect();
+        stacks.extend(self.armor.iter_mut().rev().filter_map(Option::take));
+        stacks.extend(self.offhand.take());
+        stacks.retain(|s| s.enchantment_level("minecraft:vanishing_curse") == 0);
+        self.apply_equipment();
+        for stack in stacks {
+            let r = &mut self.world.random;
+            let strength = f64::from(r.next_float()) * 0.5;
+            let angle = f64::from(r.next_float()) * std::f64::consts::TAU;
+            let v = [-angle.sin() * strength, 0.2, angle.cos() * strength];
+            self.spawn_item(stack, at, v, 40);
+        }
+    }
     fn spawn_item(
         &mut self,
         stack: ItemStack,
@@ -3649,16 +3681,8 @@ impl Game<'_> {
         // Switching hotbar slots only ends a main-hand use.
         let hand_changed = slot != self.selected && slot != shield::OFFHAND_SLOT;
         if !self.right || hand_changed || self.screen != Screen::Playing {
-            if &*stack.item == "minecraft:bow" && !hand_changed {
-                self.release_bow(ticks);
-            }
-            if &*stack.item == "minecraft:spyglass" {
-                self.stop_spyglass();
-            }
-            if &*stack.item == "minecraft:trident" && !hand_changed {
-                self.release_trident(ticks);
-            }
             self.using = None;
+            self.release_used_item(&stack, ticks, hand_changed);
             return;
         }
         let Some(info) = self.res.items().get(&stack.item).cloned() else {
@@ -3714,6 +3738,17 @@ impl Game<'_> {
             self.using = Some((slot, ticks));
         }
     }
+    /// `LivingEntity.releaseUsingItem` (`Item.releaseUsing`) for `stack`,
+    /// used for `ticks`, its hand acting: a bow or a trident lets go (not
+    /// when its hand changed), a spyglass stops scoping.
+    pub(super) fn release_used_item(&mut self, stack: &ItemStack, ticks: u32, hand_changed: bool) {
+        match &*stack.item {
+            "minecraft:bow" if !hand_changed => self.release_bow(ticks),
+            "minecraft:trident" if !hand_changed => self.release_trident(ticks),
+            "minecraft:spyglass" => self.stop_spyglass(),
+            _ => {}
+        }
+    }
     fn tick_mining(&mut self) -> Result<()> {
         if self.destroy_delay > 0 {
             self.destroy_delay -= 1;
@@ -3937,13 +3972,7 @@ impl Game<'_> {
             .as_ref()
             .map_or(0, |s| s.enchantment_level("minecraft:respiration") as i32);
         player.pitch = self.pitch;
-        // LivingEntity.canGlideUsing: a glider in its slot that will not break next.
-        player.glider = self.armor[1].as_ref().is_some_and(|s| {
-            self.res
-                .items()
-                .get(&s.item)
-                .is_some_and(|i| i.glider && (i.max_damage == 0 || s.damage + 1 < i.max_damage))
-        });
+        player.glider = self.glider_worn();
         // A saved death already dropped inventory/XP and counted the death.
         if player.health.dead_or_dying() {
             self.screen = Screen::Dead;
@@ -4021,6 +4050,7 @@ impl Game<'_> {
         let riding = self.riding.is_some();
         let ghast_collisions = self.happy_ghast_player_collisions();
         let spin_targets = self.spin_targets();
+        let glider = self.glider_worn();
         let Some(player) = self.player.as_mut() else {
             // A dedicated server has no local player: the world still runs.
             if self.options.dedicated.is_some() {
@@ -4063,13 +4093,7 @@ impl Game<'_> {
             .as_ref()
             .map_or(0, |s| s.enchantment_level("minecraft:respiration") as i32);
         player.pitch = self.pitch;
-        // LivingEntity.canGlideUsing: a glider in its slot that will not break next.
-        player.glider = self.armor[1].as_ref().is_some_and(|s| {
-            self.res
-                .items()
-                .get(&s.item)
-                .is_some_and(|i| i.glider && (i.max_damage == 0 || s.damage + 1 < i.max_damage))
-        });
+        player.glider = glider;
         // LocalPlayer.modifyInput: walking while using an item.
         player.item_use_speed = self
             .using
@@ -4306,20 +4330,8 @@ impl Game<'_> {
                 .experience
                 .death_reward(self.ui.rules.bool("keep_inventory") || self.spectator());
             self.spawn_orbs(feet, reward);
-            if !self.creative && !self.ui.rules.bool("keep_inventory") {
-                // Inventory.dropAll: slots 0..36, armor feet to head (36..39), off hand (40).
-                let mut stacks: Vec<ItemStack> =
-                    self.inventory.iter_mut().filter_map(Option::take).collect();
-                stacks.extend(self.armor.iter_mut().rev().filter_map(Option::take));
-                stacks.extend(self.offhand.take());
-                self.apply_equipment();
-                for stack in stacks {
-                    let r = &mut self.world.random;
-                    let strength = f64::from(r.next_float()) * 0.5;
-                    let angle = f64::from(r.next_float()) * std::f64::consts::TAU;
-                    let v = [-angle.sin() * strength, 0.2, angle.cos() * strength];
-                    self.spawn_item(stack, at, v, 40);
-                }
+            if !self.spectator() {
+                self.drop_inventory(at);
             }
             self.audio
                 .play("minecraft:entity.player.death", Some(at), 1.0, 1.0);

crates/horizon-client/src/game/agent.rs

@@ -335,6 +335,12 @@ impl Game<'_> {
             Some(Ticker::Shulker { .. }) => v["lid"] = json!(self.block_anim(pos, 1.0).shulker.0),
             _ => {}
         }
+        // The lines of a sign, as this client has them.
+        if let Some(horizon_client::containers::BlockEntity::Sign(sign)) =
+            self.world.block_entities.get(&(pos[0], pos[1], pos[2]))
+        {
+            v["sign"] = json!({ "front": sign.front.lines, "back": sign.back.lines });
+        }
         v
     }
     pub(super) fn stack_value(&self, s: &ItemStack) -> Value {
@@ -457,6 +463,7 @@ impl Game<'_> {
                 "velocity": [p.velocity.x, p.velocity.y, p.velocity.z],
                 "on_ground": p.ground.on_ground,
                 "flying": p.flying,
+                "fall_flying": p.fall_flying,
                 "sneaking": self.keys.contains(&KeyCode::ShiftLeft),
                 "sprinting": self.keys.contains(&KeyCode::ControlLeft),
                 "health": p.health.health(),

crates/horizon-client/src/game/books.rs

@@ -3,9 +3,10 @@
 //! pixels, 1024 characters, 100 pages), signing it into a written book,
 //! reading written books, and lecterns (placing a book, turning its pages
 //! with a redstone pulse, the comparator output and taking the book).
-use super::Game;
+use super::{Game, lan::LanHost};
 use horizon_client::{
     containers::{BlockEntity, Lectern},
+    first_person::Hand,
     hud::{HudBatch, rgba},
     item_data::WrittenBook,
     items::ItemStack,
@@ -14,6 +15,7 @@ use horizon_client::{
     ui,
 };
 use horizon_core::position::BlockPos;
+use horizon_protocol::packets::play::{self, Clientbound as C, Serverbound as S};
 use horizon_world::level::flags as level_flags;
 use std::time::Instant;
 use winit::{
@@ -48,9 +50,32 @@ impl Game<'_> {
     fn book_lines(&self, page: &str) -> Vec<Text> {
         self.gui.atlas.font.split(&Text::literal(page), 114.0)
     }
-    /// `WritableBookItem.use` / `WrittenBookItem.use`.
+    /// `WritableBookItem.use` / `WrittenBookItem.use` (`Player.openItemGui`).
+    /// A server's player writes in its own client's editor
+    /// (`LocalPlayer.openItemGui`), and reads on its own client once told to
+    /// (`ServerPlayer.openItemGui`'s ClientboundOpenBookPacket).
     pub(super) fn use_book(&mut self, stack: &ItemStack) -> bool {
-        let screen = match &*stack.item {
+        let written = match &*stack.item {
+            "minecraft:writable_book" => false,
+            "minecraft:written_book" => true,
+            _ => return false,
+        };
+        if self.lan_acting.is_some() {
+            if written {
+                let hand = i32::from(self.hand == Hand::Off);
+                self.guest_packets
+                    .push(C::OpenBook(play::OpenBook { hand }));
+            }
+        } else if let Some(screen) = self.book_screen(stack) {
+            self.open_book(screen);
+        }
+        self.swing_arm();
+        true
+    }
+    /// The screen a book in hand opens: `BookEditScreen` for a book and
+    /// quill, `BookViewScreen` for a written book.
+    fn book_screen(&self, stack: &ItemStack) -> Option<BookScreen> {
+        Some(match &*stack.item {
             "minecraft:writable_book" => {
                 let mut pages = stack
                     .data()
@@ -77,12 +102,31 @@ impl Game<'_> {
                 page: 0,
                 lectern: None,
             },
-            _ => return false,
-        };
-        self.open_book(screen);
-        self.swing_arm();
+            _ => return None,
+        })
+    }
+    /// `MultiPlayerGameMode.useItem`'s own use of a book and quill on a
+    /// server's client: its editor opens here at once.
+    pub(super) fn remote_use_book(&mut self, stack: &ItemStack) -> bool {
+        if &*stack.item != "minecraft:writable_book" {
+            return false;
+        }
+        if let Some(screen) = self.book_screen(stack) {
+            self.open_book(screen);
+        }
         true
     }
+    /// `ClientPacketListener.handleOpenBook`: the written book in that hand.
+    pub(super) fn remote_open_book(&mut self, hand: i32) {
+        let hand = if hand == 1 { Hand::Off } else { Hand::Main };
+        let screen = self.with_hand(hand, |g| {
+            let stack = g.held().filter(|s| &*s.item == "minecraft:written_book")?;
+            g.book_screen(&stack.clone())
+        });
+        if let Some(screen) = screen {
+            self.open_book(screen);
+        }
+    }
     fn open_book(&mut self, screen: BookScreen) {
         self.book = Some(screen);
         self.keys.clear();
@@ -104,7 +148,9 @@ impl Game<'_> {
         self.book = None;
         self.capture(true);
     }
-    /// `BookEditScreen.saveChanges`: trailing empty pages dropped.
+    /// `BookEditScreen.saveChanges` and `BookSignScreen`'s Sign and Close:
+    /// trailing empty pages dropped, the book in hand updated here and, on a
+    /// server's client, sent (ServerboundEditBookPacket).
     fn save_book(&mut self, sign: bool) {
         let Some(BookScreen::Edit {
             slot, pages, title, ..
@@ -116,29 +162,59 @@ impl Game<'_> {
         while pages.len() > 1 && pages.last().is_some_and(String::is_empty) {
             pages.pop();
         }
-        if let Some(stack) = self.stack_in_mut(slot).as_mut()
-            && &*stack.item == "minecraft:writable_book"
-        {
-            if sign {
-                let mut written = ItemStack::new("minecraft:written_book", 1);
-                written.data_mut().written = Some(WrittenBook {
-                    title: title.trim().to_owned(),
-                    author: super::chat::PLAYER_NAME.to_owned(),
-                    generation: 0,
-                    pages,
-                });
-                *stack = written;
-            } else {
-                stack.data_mut().writable_pages = if pages.iter().all(String::is_empty) {
-                    Vec::new()
-                } else {
-                    pages
-                };
-                stack.tidy();
-            }
+        let title = sign.then(|| title.trim().to_owned());
+        if self.remote.is_some() {
+            self.send(S::EditBook(play::EditBook {
+                slot: slot as i32,
+                pages: pages.clone(),
+                title: title.clone(),
+            }));
         }
+        self.write_book(slot, pages, title);
         self.capture(true);
     }
+    /// The book and quill at `slot` takes the pages, or with a title becomes
+    /// the written book its writer signed.
+    fn write_book(&mut self, slot: usize, pages: Vec<String>, title: Option<String>) {
+        let author = self
+            .lan_acting_name
+            .clone()
+            .unwrap_or_else(|| super::chat::PLAYER_NAME.to_owned());
+        let Some(stack) = self
+            .stack_in_mut(slot)
+            .as_mut()
+            .filter(|s| &*s.item == "minecraft:writable_book")
+        else {
+            return;
+        };
+        if let Some(title) = title {
+            let mut written = ItemStack::new("minecraft:written_book", 1);
+            written.data_mut().written = Some(WrittenBook {
+                title,
+                author,
+                generation: 0,
+                pages,
+            });
+            *stack = written;
+        } else {
+            stack.data_mut().writable_pages = if pages.iter().all(String::is_empty) {
+                Vec::new()
+            } else {
+                pages
+            };
+            stack.tidy();
+        }
+    }
+    /// `ServerGamePacketListenerImpl.handleEditBook`: a guest's book in a
+    /// hotbar slot or its off hand (`updateBookContents`, `signBook`).
+    pub(super) fn lan_edit_book(&mut self, host: &mut LanHost, conn: u32, p: play::EditBook) {
+        if !((0..9).contains(&p.slot) || p.slot == super::shield::OFFHAND_SLOT as i32) {
+            return;
+        }
+        self.as_guest(host, conn, |g| {
+            g.write_book(p.slot as usize, p.pages, p.title)
+        });
+    }
     pub(super) fn book_key(&mut self, event: &KeyEvent) {
         if event.state != ElementState::Pressed {
             return;
@@ -519,7 +595,26 @@ impl Game<'_> {
                 Some(key) => self.lectern_button(key, 3),
                 None => return Err("not a lectern".into()),
             },
-            Some("done") => self.close_book(),
+            // The book and quill's buttons: Sign, then Sign and Close; Done
+            // (which saves), then Cancel.
+            Some("sign") => match self.book.as_mut() {
+                Some(BookScreen::Edit {
+                    signing: true,
+                    title,
+                    ..
+                }) if !title.trim().is_empty() => self.save_book(true),
+                Some(BookScreen::Edit { signing, .. }) => *signing = true,
+                _ => return Err("not a book and quill".into()),
+            },
+            Some("done") => match self.book.as_mut() {
+                Some(BookScreen::Edit { signing: true, .. }) => {
+                    if let Some(BookScreen::Edit { signing, .. }) = self.book.as_mut() {
+                        *signing = false;
+                    }
+                }
+                Some(BookScreen::Edit { .. }) => self.save_book(false),
+                _ => self.close_book(),
+            },
             Some(other) => return Err(format!("unknown book button {other}").into()),
         }
         Ok(match &self.book {

crates/horizon-client/src/game/control.rs

@@ -232,6 +232,13 @@ impl Game<'_> {
             "key" => {
                 let key = key_code(arg(1)?).ok_or_else(|| format!("unknown key {}", words[1]))?;
                 self.require_world()?;
+                // The sign editor takes raw presses (Enter, arrows, Backspace, Escape).
+                if self.sign_edit.is_some() {
+                    if arg(2)? != "up" {
+                        self.sign_input(Some(key), None);
+                    }
+                    return ok();
+                }
                 // A held edit modifier (`key super down`) and A/C/V/X: the
                 // open book's Select All, Copy, Paste or Cut.
                 if self.book.is_some() && arg(2)? != "up" {
@@ -524,6 +531,10 @@ impl Game<'_> {
                     self.book_type(text);
                     return ok();
                 }
+                if self.sign_edit.is_some() {
+                    self.sign_input(None, Some(text));
+                    return ok();
+                }
                 match self.screen {
                     Screen::Chat => self.chat_type(text),
                     Screen::CommandBlock => self.command_block_type(text),
@@ -549,7 +560,7 @@ impl Game<'_> {
                     }
                     _ => {
                         return Err(
-                            "type needs the chat screen (key t tap), the language search, the creative search, the anvil or World Options".into(),
+                            "type needs the chat screen (key t tap), a sign or book, the language search, the creative search, the anvil or World Options".into(),
                         );
                     }
                 }

crates/horizon-client/src/game/creatures.rs

@@ -47,6 +47,8 @@ pub(super) struct Creatures {
     pub pearl_cooldown: u32,
     /// The wind charge's use cooldown (ticks).
     pub wind_cooldown: u32,
+    /// Wind bursts from a guest's turn, waiting for it to end (game/wind.rs).
+    pub wind_bursts: Vec<super::wind::Burst>,
     /// Ticks left of the elder guardian's apparition (MobAppearanceParticle).
     pub elder_apparition: i32,
     /// The wandering trader spawner's clock.
@@ -1778,7 +1780,7 @@ impl Game<'_> {
                 _ => self.projectile_hit(&p, hit)?,
             }
         }
-        Ok(())
+        self.flush_wind_bursts()
     }
     /// `projectile_hit` for a projectile the guest `conn` shot, run as them;
     /// as the host's when they have left.

crates/horizon-client/src/game/lan.rs

@@ -411,7 +411,12 @@ impl Game<'_> {
                     "game_mode": g.game_mode,
                     // ItemCooldowns: the ticks the shield an axe disabled stays down.
                     "shield_cooldown": h.play.get(&g.conn).map_or(0, |p| p.shield_cooldown),
+                    // The item the server has this guest using: its slot and ticks.
+                    "using": h.play.get(&g.conn).and_then(|p| p.using())
+                        .map(|(slot, ticks)| json!({ "slot": slot, "ticks": ticks })),
                     "sneaking": g.sneaking,
+                    // The server's Elytra glide (shared flag 7).
+                    "fall_flying": g.fall_flying,
                     "sleeping": g.bed,
                     "health": g.health,
                     // The server's body: its air supply and golden hearts.
@@ -1006,6 +1011,8 @@ impl Game<'_> {
         drop(holding);
         lan::flush_all(host.hub.guests.iter().map(|g| &g.sender));
         self.lan = Some(host);
+        // A mace's wind burst from a guest's attack.
+        let _ = self.flush_wind_bursts();
     }
 
     fn lan_guest_joined(

crates/horizon-client/src/game/lan_actions.rs

@@ -30,6 +30,8 @@ use winit::keyboard::KeyCode;
 /// Per-guest state of the gameplay code that lives outside `Guest`.
 #[derive(Default)]
 pub(super) struct GuestPlay {
+    /// The sign this guest may write on (`SignBlockEntity.playerWhoMayEdit`).
+    pub(super) sign_editing: Option<[i32; 3]>,
     mining: Option<Mining>,
     destroy_delay: u32,
     using: Option<(usize, u32)>,
@@ -259,6 +261,7 @@ impl Game<'_> {
         motion.pitch = g.pitch;
         motion.sprinting = g.sprinting;
         motion.may_fly = g.creative() || g.game_mode == SPECTATOR;
+        motion.flying = g.flying;
         motion.invulnerable = motion.may_fly;
         let _ = motion.set_health(g.health, false);
         motion.health.food.food = g.food;
@@ -513,7 +516,8 @@ impl Game<'_> {
         std::mem::swap(&mut self.mount, &mut play.mount);
         self.container = container;
         self.screen = screen;
-        self.sign_edit = host_sign;
+        // A sign the guest's placement opened (SignBlock.openTextEdit).
+        let guest_sign = std::mem::replace(&mut self.sign_edit, host_sign);
         // A lectern the guest's use opened (LecternBlock.openScreen).
         let guest_lectern = match std::mem::replace(&mut self.book, host_book) {
             Some(super::books::BookScreen::View {
@@ -652,6 +656,9 @@ impl Game<'_> {
         if let Some(station) = opened_station {
             self.lan_station_opened(host, conn, station);
         }
+        if let Some(edit) = guest_sign {
+            self.lan_open_sign_editor(host, conn, edit);
+        }
         if let Some(key) = guest_lectern {
             self.lan_open_lectern(host, conn, key);
         }
@@ -865,14 +872,20 @@ impl Game<'_> {
                         self.as_guest(host, conn, |g| g.drop_held(a.action == 4));
                     }
                 }
+                // RELEASE_USE_ITEM: ServerPlayer.releaseUsingItem, with the
+                // hand of the item in use acting.
                 6 => {
                     self.as_guest(host, conn, |g| {
-                        if let Some((slot, ticks)) = g.using.take()
-                            && g.stack_in(slot)
-                                .is_some_and(|s| &*s.item == "minecraft:bow")
-                        {
-                            g.release_bow(ticks);
-                        }
+                        let Some(hand) = g.used_hand() else {
+                            return;
+                        };
+                        g.with_hand(hand, |g| {
+                            if let Some((slot, ticks)) = g.using.take()
+                                && let Some(stack) = g.stack_in(slot).cloned()
+                            {
+                                g.release_used_item(&stack, ticks, false);
+                            }
+                        });
                     });
                 }
                 // SWAP_ITEM_WITH_OFFHAND: the hands swap and the item in use stops
@@ -1029,10 +1042,13 @@ impl Game<'_> {
                     g.open_ridden_mount_menu();
                 });
             }
+            S::PlayerCommand(p) if p.action == 6 => self.lan_start_gliding(host, conn),
             S::ContainerButtonClick(p) => {
                 self.lan_station_button(host, conn, p.container, p.button);
             }
             S::RenameItem(p) => self.lan_station_rename(host, conn, &p.name),
+            S::SignUpdate(p) => self.lan_sign_update(host, conn, p),
+            S::EditBook(p) => self.lan_edit_book(host, conn, p),
             S::ContainerSlotStateChanged(p) => {
                 self.lan_crafter_slot_state(host, conn, p.container, p.slot, p.enabled);
             }
@@ -1727,6 +1743,9 @@ impl Game<'_> {
                 }
                 .death_reward(self.ui.rules.bool("keep_inventory") || g.game_mode == SPECTATOR);
                 let (name, uuid) = (g.name.clone(), g.uuid);
+                // ServerPlayer.die: dropAllDeathLoot unless a spectator, from the eyes less 0.3.
+                let drops = (g.game_mode != SPECTATOR)
+                    .then(|| [at[0], at[1] + g.eye_height() - 0.3, at[2]]);
                 let cause = host.play.get_mut(&conn).and_then(|p| p.death_cause.take());
                 let message = match cause {
                     // ServerPlayer.die: the death message, to everyone unless
@@ -1760,6 +1779,9 @@ impl Game<'_> {
                 );
                 // LivingEntity.die: the death animation, the dying player included.
                 host.hub.entity_event(id, 3, at);
+                if let Some(eyes) = drops {
+                    self.as_guest(host, conn, |game| game.drop_inventory(eyes));
+                }
                 self.spawn_orbs(at, reward);
             }
         }
@@ -1846,6 +1868,13 @@ impl Game<'_> {
     /// sounds are heard at the guest.
     fn guest_server_tick(&mut self, host: &mut LanHost, conn: u32) {
         self.guest_vehicle_tick(host, conn);
+        // The last move's fall stands in for the server's delta movement.
+        let fell = host
+            .hub
+            .guest_mut(conn)
+            .and_then(|g| g.moves.last().map(|m| m.0[1]))
+            .unwrap_or(0.0);
+        self.guest_glide_tick(host, conn, fell);
         let Some(g) = host.hub.guest_mut(conn) else {
             return;
         };
@@ -1963,6 +1992,87 @@ impl Game<'_> {
         }
     }
 
+    /// ServerGamePacketListenerImpl.handlePlayerCommand START_FALL_FLYING:
+    /// `Player.tryToStartFallFlying`, or else `stopFallFlying` (a second
+    /// start while gliding ends the glide, as in vanilla).
+    fn lan_start_gliding(&mut self, host: &mut LanHost, conn: u32) {
+        let Some(g) = host.hub.guest_mut(conn) else {
+            return;
+        };
+        let start = !g.fall_flying && self.guest_can_glide(host, conn) == Some(true);
+        let in_liquid = self
+            .as_guest(host, conn, |game| {
+                game.player
+                    .as_ref()
+                    .is_some_and(|p| p.fluids.was_touching_water || p.is_in_lava())
+            })
+            .unwrap_or(true);
+        if let Some(g) = host.hub.guest_mut(conn) {
+            g.fall_flying = start && !in_liquid;
+        }
+    }
+
+    /// `Player.canGlide`: not flying, airborne, not riding, no levitation, and
+    /// a glider that its next point of wear won't break.
+    fn guest_can_glide(&mut self, host: &mut LanHost, conn: u32) -> Option<bool> {
+        let g = host.hub.guest_mut(conn)?;
+        if g.flying || g.on_ground || g.vehicle.is_some() {
+            return Some(false);
+        }
+        self.as_guest(host, conn, |game| {
+            game.glider_worn() && game.potions.effects.get("levitation").is_none()
+        })
+    }
+
+    /// `LivingEntity.updateFallFlying` on the server, once a tick for a
+    /// gliding guest: the glide ends once `canGlide` fails; otherwise every
+    /// 20th tick wears the glider by one, and every 10th is an
+    /// `elytra_glide` game event. Entity.checkFallDistanceAccumulation runs
+    /// first: a glide that isn't diving keeps the fall distance at 1.
+    fn guest_glide_tick(&mut self, host: &mut LanHost, conn: u32, fell: f64) {
+        let Some(g) = host.hub.guest_mut(conn) else {
+            return;
+        };
+        if !g.fall_flying {
+            if let Some(m) = g.motion.as_mut() {
+                m.fall_fly_ticks = 0;
+            }
+            return;
+        }
+        let creative = g.creative();
+        if let Some(m) = g.motion.as_mut()
+            && fell > -0.5
+            && m.fall_distance > 1.0
+        {
+            m.fall_distance = 1.0;
+        }
+        if self.guest_can_glide(host, conn) != Some(true) {
+            if let Some(g) = host.hub.guest_mut(conn) {
+                g.fall_flying = false;
+            }
+            return;
+        }
+        self.as_guest(host, conn, |game| {
+            let Some(p) = game.player.as_mut() else {
+                return;
+            };
+            p.fall_fly_ticks += 1;
+            let next = p.fall_fly_ticks + 1;
+            let at = [p.position.x, p.position.y, p.position.z];
+            if next % 10 != 0 {
+                return;
+            }
+            if (next / 10) % 2 == 0
+                && !creative
+                && let Some(elytra) = game.armor[1].as_mut()
+            {
+                elytra.damage += 1;
+            }
+            let ctx = game.player_context(None);
+            game.post_game_event("minecraft:elytra_glide", at, ctx);
+        });
+    }
+
     /// `Player.isInWall`: a suffocating block in the 0.48-wide box at the
     /// eyes. Suffocating is a full collision box that is also a full render
     /// cube (`BlockBehaviour.isSuffocating`'s default; glass and the like

crates/horizon-client/src/game/lan_particles.rs

@@ -3,7 +3,7 @@
 //! `/particle` uses) and `ClientboundExplodePacket` (`ServerLevel.explode`).
 use super::Game;
 use horizon_client::particles::{ParticleOptions, ParticleType};
-use horizon_core::random::RandomSource;
+use horizon_core::{geometry::Vec3, random::RandomSource};
 use horizon_protocol::{
     entity_data::{Particle, ParticleData},
     packets::play::{self, Clientbound as C},
@@ -154,7 +154,7 @@ impl Game<'_> {
     }
 
     /// `ClientPacketListener.handleExplosion`: the blast's particles (and its
-    /// sound, when the packet carries it).
+    /// sound, when the packet carries it), then the player's push.
     pub(super) fn remote_explode(&mut self, p: &play::Explode) {
         if p.play_sound {
             let pitch = (1.0
@@ -168,37 +168,88 @@ impl Game<'_> {
                 pitch,
             );
         }
-        let (world, facts) = (&self.world, self.res.facts());
-        self.particles
-            .explosion(p.center, p.radius, p.block_count.max(0) as usize, &|b| {
-                facts.is_air(world.block(b[0], b[1], b[2]))
-            });
+        if let Some(options) = self.received_particle(&p.particle, p.center) {
+            self.particles.add(&options, p.center, [1.0, 0.0, 0.0]);
+        }
+        // A wind charge's burst throws none.
+        if !p.block_particles.is_empty() {
+            let (world, facts) = (&self.world, self.res.facts());
+            self.particles.explosion_blocks(
+                p.center,
+                p.radius,
+                p.block_count.max(0) as usize,
+                &|b| facts.is_air(world.block(b[0], b[1], b[2])),
+            );
+        }
+        // Entity.pushFromExplosion.
+        if let (Some(push), Some(player)) = (p.knockback, self.player.as_mut()) {
+            player.velocity = Vec3::new(
+                player.velocity.x + push[0],
+                player.velocity.y + push[1],
+                player.velocity.z + push[2],
+            );
+        }
     }
 
     /// `ServerLevel.explode`'s packet to each player within 64 blocks. The
     /// sound and the push reach them on their own (the level's sounds, the
-    /// players' motion), so the packet carries neither.
+    /// motion a hurt player is sent), so the packet carries neither.
     pub(super) fn lan_explode(&self, center: [f64; 3], radius: f32, block_count: usize) {
-        let Some(host) = self.lan.as_ref() else {
-            return;
-        };
-        let particle = |name: &str| {
-            Some(Particle {
-                id: host.hub.registry_id("minecraft:particle_type", name)?,
-                data: None,
-            })
-        };
         let emitter = if radius < 2.0 {
             "minecraft:explosion"
         } else {
             "minecraft:explosion_emitter"
         };
-        let (Some(at_center), Some(poof), Some(smoke)) = (
-            particle(emitter),
-            particle("minecraft:poof"),
-            particle("minecraft:smoke"),
-        ) else {
-            return;
+        let sound = "minecraft:entity.generic.explode";
+        if let Some(packet) =
+            self.explosion_packet(center, radius, block_count, emitter, sound, true)
+        {
+            self.send_explosion(packet, &[]);
+        }
+    }
+
+    /// A wind charge's burst (`AbstractWindCharge.explode`): gust emitters,
+    /// no block particles, and for each player it pushed the push
+    /// (`ServerExplosion.hitPlayers`), which only that client applies, as
+    /// nothing hurt them.
+    pub(super) fn lan_wind_burst(
+        &self,
+        center: [f64; 3],
+        radius: f32,
+        sound: &str,
+        block_count: usize,
+        pushed: &[(u32, [f64; 3])],
+    ) {
+        let emitter = if radius < 2.0 {
+            "minecraft:gust_emitter_small"
+        } else {
+            "minecraft:gust_emitter_large"
+        };
+        if let Some(packet) =
+            self.explosion_packet(center, radius, block_count, emitter, sound, false)
+        {
+            self.send_explosion(packet, pushed);
+        }
+    }
+
+    /// `ClientboundExplodePacket` without a push, or None while not serving.
+    /// The sound is the level's, which the players hear already, so it isn't
+    /// played from the packet.
+    fn explosion_packet(
+        &self,
+        center: [f64; 3],
+        radius: f32,
+        block_count: usize,
+        emitter: &str,
+        sound: &str,
+        block_particles: bool,
+    ) -> Option<play::Explode> {
+        let hub = &self.lan.as_ref()?.hub;
+        let particle = |name: &str| {
+            Some(Particle {
+                id: hub.registry_id("minecraft:particle_type", name)?,
+                data: None,
+            })
         };
         // Level.DEFAULT_EXPLOSION_BLOCK_PARTICLES.
         let info = |particle, scaling| play::ExplosionParticle {
@@ -207,22 +258,49 @@ impl Game<'_> {
             speed: 1.0,
             weight: 1,
         };
-        let packet = C::Explode(play::Explode {
+        let block_particles = if block_particles {
+            vec![
+                info(particle("minecraft:poof")?, 0.5),
+                info(particle("minecraft:smoke")?, 1.0),
+            ]
+        } else {
+            Vec::new()
+        };
+        Some(play::Explode {
             center,
             radius,
             block_count: block_count as i32,
             knockback: None,
-            particle: at_center,
-            sound: match host
-                .hub
-                .registry_id("minecraft:sound_event", "minecraft:entity.generic.explode")
-            {
+            particle: particle(emitter)?,
+            sound: match hub.registry_id("minecraft:sound_event", sound) {
                 Some(id) => (id, None),
-                None => (-1, Some(("minecraft:entity.generic.explode".into(), None))),
+                None => (-1, Some((sound.into(), None))),
             },
-            block_particles: vec![info(poof, 0.5), info(smoke, 1.0)],
+            block_particles,
             play_sound: false,
-        });
-        host.hub.broadcast_near(center, 64.0, &packet, None);
+        })
+    }
+
+    /// `packet` to each player within 64 blocks of its centre, with the push
+    /// `pushed` holds for them.
+    fn send_explosion(&self, mut packet: play::Explode, pushed: &[(u32, [f64; 3])]) {
+        let Some(host) = self.lan.as_ref() else {
+            return;
+        };
+        let center = packet.center;
+        let plain = C::Explode(packet.clone()).encode();
+        for g in host.hub.guests.iter().filter(|g| host.hub.here(g)) {
+            let d: f64 = (0..3).map(|k| (g.position[k] - center[k]).powi(2)).sum();
+            if d >= 4096.0 {
+                continue;
+            }
+            match pushed.iter().find(|(conn, _)| *conn == g.conn) {
+                Some((_, push)) => {
+                    packet.knockback = Some(*push);
+                    g.send(&C::Explode(packet.clone()));
+                }
+                None => g.sender.send(plain.clone()),
+            }
+        }
     }
 }

crates/horizon-client/src/game/lan_stations.rs

@@ -588,17 +588,7 @@ impl Game<'_> {
             let [x, y, z] = gs.pos;
             let name = &self.res.facts().get(self.world.block(x, y, z)).name;
             let block = StationKind::from_block(name) == Some(gs.kind);
-            let eye = [g.position[0], g.position[1] + g.eye_height(), g.position[2]];
-            // The block interaction range (4.5, creative 5) and the buffer.
-            let reach = if g.creative() { 5.0 } else { 4.5 } + 4.0;
-            let near = (0..3)
-                .map(|k| {
-                    let lo = f64::from(gs.pos[k]);
-                    (lo - eye[k]).max(eye[k] - lo - 1.0).max(0.0).powi(2)
-                })
-                .sum::<f64>()
-                < reach * reach;
-            if !(block && near) {
+            if !(block && within_reach(g, gs.pos)) {
                 let window = gs.window;
                 self.lan_station_closed(host, conn, Some(window));
                 host.hub.send_to(
@@ -670,3 +660,18 @@ pub(super) fn station_inputs(gs: &GuestStation) -> Vec<ItemStack> {
         .map(|(_, _, inputs)| inputs.filter_map(|s| gs.menu.slot(s).cloned()).collect())
         .unwrap_or_default()
 }
+
+/// `Player.isWithinBlockInteractionRange(pos, 4)`: the guest's eyes within
+/// its block interaction range (4.5, creative 5) and a 4-block buffer of the
+/// block's box.
+pub(super) fn within_reach(g: &horizon_client::lan::guest::Guest, pos: [i32; 3]) -> bool {
+    let eye = [g.position[0], g.position[1] + g.eye_height(), g.position[2]];
+    let reach = if g.creative() { 5.0 } else { 4.5 } + 4.0;
+    (0..3)
+        .map(|k| {
+            let lo = f64::from(pos[k]);
+            (lo - eye[k]).max(eye[k] - lo - 1.0).max(0.0).powi(2)
+        })
+        .sum::<f64>()
+        < reach * reach
+}

crates/horizon-client/src/game/remote.rs

@@ -641,6 +641,22 @@ impl Game<'_> {
                     ("mob_factor", Tag::Float(v[5].to_bits())),
                 ]),
                 Component::Profile(p) => profile_tag(p),
+                // ItemStackTemplate.CODEC: id, count and components.
+                Component::Stacks(stacks) => Tag::List(
+                    stacks
+                        .iter()
+                        .map(|t| {
+                            let mut entries = vec![
+                                ("id", Tag::String(self.item_name(t.item).as_ref().into())),
+                                ("count", Tag::Int(t.count)),
+                            ];
+                            if let Some(c) = self.protocol_components(t) {
+                                entries.push(("components", c));
+                            }
+                            Tag::compound(entries)
+                        })
+                        .collect(),
+                ),
                 Component::CustomModelData {
                     floats,
                     flags,
@@ -2557,6 +2573,8 @@ impl Game<'_> {
                 self.drop_remote_chunks_out_of_range();
             }
             C::BlockEntityData(p) => self.remote_block_entity_data(p.pos, p.kind, &p.tag),
+            C::OpenSignEditor(p) => self.remote_open_sign_editor(p),
+            C::OpenBook(p) => self.remote_open_book(p.hand),
             // handleSetSpawn: ClientLevel.setRespawnData, which spawn compasses point at.
             C::SetDefaultSpawnPosition(p) => {
                 let [x, y, z] = p.pos.pos;
@@ -3129,6 +3147,12 @@ impl Game<'_> {
             .as_ref()
             .map_or(0, |s| s.enchantment_level("minecraft:respiration") as i32);
         player.fluids.fast_lava = self.dim == Dim::Nether;
+        let glider = self.glider_worn();
+        let Some(player) = self.player.as_mut() else {
+            return Ok(());
+        };
+        player.glider = glider;
+        let was_gliding = player.fall_flying;
         let dead = self.screen == Screen::Dead;
         // LivingEntity.isImmobile: a sleeper lies still in the bed.
         if let Some(head) = self.sleeping {
@@ -3153,6 +3177,9 @@ impl Game<'_> {
         // LocalPlayer.onUpdateAbilities: flight turned on or off (a double
         // jump, a spectator, landing) is sent to the server.
         let flying = player.flying;
+        // LocalPlayer.aiStep: a glide this client started is sent to the
+        // server (ServerboundPlayerCommandPacket START_FALL_FLYING).
+        let started_gliding = player.fall_flying && !was_gliding;
         let events = std::mem::take(&mut player.events);
         self.previous_eye = self.eye;
         self.eye += (player.dimensions.eye_height - self.eye) * 0.5;
@@ -3192,6 +3219,14 @@ impl Game<'_> {
                 flags: if flying { 2 } else { 0 },
             }));
         }
+        if started_gliding {
+            let id = self.remote.as_ref().map_or(0, |r| r.entity_id);
+            self.send(S::PlayerCommand(play::PlayerCommand {
+                id,
+                action: 6,
+                data: 0,
+            }));
+        }
         self.remote_send_state(input);
         Ok(())
     }
@@ -4010,21 +4045,60 @@ impl Game<'_> {
             return false;
         };
         // MultiPlayerGameMode.useItem runs the use here too: food starts
-        // being eaten (Consumable.startConsuming).
+        // being eaten (Consumable.startConsuming), a book and quill opens.
         self.with_hand(hand, |g| g.start_eating(&info));
-        // BowItem.use: startUsingItem here too (with an arrow, or in creative), so that letting
-        // go sends RELEASE_USE_ITEM (Minecraft.handleKeybinds) and the server shoots.
-        if &*held.item == "minecraft:bow" {
-            self.with_hand(hand, |g| {
-                if g.using.is_none() && (g.creative || g.projectile_slot("minecraft:bow").is_some())
-                {
-                    g.using = Some((g.held_slot(), 0));
-                }
-            });
+        if self.with_hand(hand, |g| g.remote_use_book(&held)) {
+            return true;
         }
+        self.with_hand(hand, |g| g.remote_start_held_use(&held));
         item_has_use(&info)
     }
 
+    /// `Item.use` runs on the client too (MultiPlayerGameMode.useItem): an
+    /// item held in use until the button lets go starts being used here, so
+    /// that letting go sends RELEASE_USE_ITEM (Minecraft.handleKeybinds) and
+    /// the server ends the use: a bow or a trident is let go, a crossbow's
+    /// charge ends, a shield is lowered, a spyglass stops scoping. Their
+    /// sounds, loaded arrows and thrown tridents come from the server.
+    fn remote_start_held_use(&mut self, held: &ItemStack) {
+        if self.using.is_some() {
+            return;
+        }
+        let start = match &*held.item {
+            // BowItem.use: with an arrow, or in creative.
+            "minecraft:bow" => self.creative || self.projectile_slot("minecraft:bow").is_some(),
+            // CrossbowItem.use: charging when not charged and with ammunition;
+            // a charged one shoots on the server.
+            "minecraft:crossbow" => {
+                held.data().is_none_or(|d| d.charged.is_empty())
+                    && (self.creative || self.projectile_slot("minecraft:crossbow").is_some())
+            }
+            // TridentItem.use: not about to break, Riptide only in water or rain.
+            "minecraft:trident" => {
+                self.use_trident(held);
+                return;
+            }
+            // SpyglassItem.use (its sound is the server's).
+            "minecraft:spyglass" => true,
+            // ShieldItem.use: anything that blocks attacks, off cooldown.
+            _ => {
+                self.raise_shield(self.held_slot());
+                return;
+            }
+        };
+        if start {
+            self.using = Some((self.held_slot(), 0));
+        }
+    }
+    /// Whether `stack` stays in use until the button lets go (bows,
+    /// crossbows, tridents, spyglasses, shields): its use only counts ticks here.
+    fn held_until_released(&self, stack: &ItemStack) -> bool {
+        matches!(
+            &*stack.item,
+            "minecraft:bow" | "minecraft:crossbow" | "minecraft:trident" | "minecraft:spyglass"
+        ) || self.blocks_attacks(stack).is_some()
+    }
+
     /// The rest of Minecraft.startUseItem once the main hand's target passed:
     /// the main hand's item, then the off hand's turn (its block, its item).
     /// The server does each packet's part with that packet's hand only.
@@ -4043,7 +4117,8 @@ impl Game<'_> {
         }
         self.remote_use_item(Hand::Off);
     }
-    /// `LivingEntity.updatingUsingItem` on a server client: a drawn bow, and a
+    /// `LivingEntity.updatingUsingItem` on a server client: an item held in
+    /// use (`held_until_released`), and a
     /// consumable's eating animation and its crumbs. The server eats it and
     /// sends the stack, the hunger and the sounds.
     fn remote_tick_using(&mut self) {
@@ -4051,8 +4126,9 @@ impl Game<'_> {
             return;
         };
         let stack = self.stack_in(slot).cloned();
-        // A drawn bow: held until the button lets go (or another slot is picked).
-        if stack.as_ref().is_some_and(|s| &*s.item == "minecraft:bow") {
+        // A drawn bow, a charging crossbow, a raised shield...: held until
+        // the button lets go (or another slot is picked).
+        if stack.as_ref().is_some_and(|s| self.held_until_released(s)) {
             self.using = (slot == self.selected || slot == super::shield::OFFHAND_SLOT)
                 .then_some((slot, ticks + 1));
             return;

crates/horizon-client/src/game/shader_packs.rs

@@ -69,7 +69,7 @@ impl Game<'_> {
             }
         };
         if let Some(r) = self.renderer.as_mut()
-            && let Err(e) = r.set_shader_pack(pack.as_ref())
+            && let Err(e) = r.set_shader_pack(pack.as_ref(), &self.pack.render.sprite_layers)
         {
             return self.shader_pack_error(&id, &e.to_string());
         }
@@ -79,7 +79,10 @@ impl Game<'_> {
     /// Give the loaded pack to the renderer (also after it is rebuilt).
     pub(super) fn apply_shader_pack(&mut self) -> horizon_client::Result<()> {
         match self.renderer.as_mut() {
-            Some(r) => r.set_shader_pack(self.shader_packs.pack.as_ref()),
+            Some(r) => r.set_shader_pack(
+                self.shader_packs.pack.as_ref(),
+                &self.pack.render.sprite_layers,
+            ),
             None => Ok(()),
         }
     }

crates/horizon-client/src/game/sign_edit.rs

@@ -1,12 +1,13 @@
 //! The sign editing screen (`SignEditScreen` / `HangingSignEditScreen`):
 //! opened when a sign is placed, four lines limited to the sign's line
 //! width, Up/Down/Enter move between lines, Escape or Done closes.
-use super::Game;
+use super::{Game, lan::LanHost};
 use horizon_client::{
     containers::BlockEntity,
     hud::{HudBatch, rgba},
     signs::wood_type,
 };
+use horizon_protocol::packets::play::{self, Clientbound as C, Serverbound as S};
 use std::time::Instant;
 use winit::{
     event::{ElementState, KeyEvent},
@@ -33,14 +34,95 @@ impl Game<'_> {
         self.right = false;
         self.capture(false);
     }
+    /// `AbstractSignEditScreen.removed`: a server's client sends what it
+    /// wrote (ServerboundSignUpdatePacket); the window's own world keeps it
+    /// and sends it to its guests (`sendBlockUpdated`).
     pub(super) fn close_sign_editor(&mut self) {
         if let Some(edit) = self.sign_edit.take() {
-            self.world
-                .modified
-                .insert((edit.pos.0 >> 4, edit.pos.2 >> 4));
+            if self.remote.is_some() {
+                if let Some(BlockEntity::Sign(sign)) = self.world.block_entities.get(&edit.pos) {
+                    let side = if edit.front { &sign.front } else { &sign.back };
+                    self.send(S::SignUpdate(play::SignUpdate {
+                        pos: [edit.pos.0, edit.pos.1, edit.pos.2],
+                        lines: side.lines.clone(),
+                        front: edit.front,
+                    }));
+                }
+            } else {
+                self.mark_block_entity_updated(edit.pos);
+            }
         }
         self.capture(true);
     }
+    /// `ServerPlayer.openTextEdit` for the guest whose action opened a sign:
+    /// the block, then the editor, on its client, and the guest may write on it.
+    pub(super) fn lan_open_sign_editor(&mut self, host: &mut LanHost, conn: u32, edit: SignEditor) {
+        let pos = [edit.pos.0, edit.pos.1, edit.pos.2];
+        let state = self.world.block(pos[0], pos[1], pos[2]).0 as i32;
+        host.hub
+            .send_to(conn, &C::BlockUpdate(play::BlockUpdate { pos, state }));
+        host.hub.send_to(
+            conn,
+            &C::OpenSignEditor(play::OpenSignEditor {
+                pos,
+                front: edit.front,
+            }),
+        );
+        host.play.entry(conn).or_default().sign_editing = Some(pos);
+    }
+    /// `ServerGamePacketListenerImpl.handleSignUpdate`: the lines, formatting
+    /// codes stripped, go on the sign the guest may write on unless it is
+    /// waxed (`SignBlockEntity.updateSignText`); a guest gone out of reach
+    /// may no longer write (`playerIsTooFarAwayToEdit`).
+    pub(super) fn lan_sign_update(&mut self, host: &mut LanHost, conn: u32, p: play::SignUpdate) {
+        let Some(g) = host.hub.guest(conn) else {
+            return;
+        };
+        let near = super::lan_stations::within_reach(g, p.pos);
+        let Some(play) = host.play.get_mut(&conn) else {
+            return;
+        };
+        if !near {
+            play.sign_editing = None;
+        }
+        if play.sign_editing != Some(p.pos) {
+            log::warn!("{} just tried to change non-editable sign", g.name);
+            return;
+        }
+        let key = (p.pos[0], p.pos[1], p.pos[2]);
+        let Some(BlockEntity::Sign(sign)) = self.world.block_entities.get_mut(&key) else {
+            return;
+        };
+        if sign.waxed {
+            return;
+        }
+        let side = if p.front {
+            &mut sign.front
+        } else {
+            &mut sign.back
+        };
+        for (line, new) in side.lines.iter_mut().zip(&p.lines) {
+            *line = horizon_client::clipboard::strip_formatting(new);
+        }
+        play.sign_editing = None;
+        self.mark_block_entity_updated(key);
+    }
+    /// `ClientPacketListener.handleOpenSignEditor`: the editor on a sign this
+    /// client has.
+    pub(super) fn remote_open_sign_editor(&mut self, p: play::OpenSignEditor) {
+        let key = (p.pos[0], p.pos[1], p.pos[2]);
+        if matches!(
+            self.world.block_entities.get(&key),
+            Some(BlockEntity::Sign(_))
+        ) {
+            self.open_sign_editor(key, p.front);
+        } else {
+            log::warn!(
+                "ignoring openTextEdit on a block that is no sign at {:?}",
+                p.pos
+            );
+        }
+    }
     pub(super) fn sign_edit_key(&mut self, event: &KeyEvent) {
         if event.state != ElementState::Pressed {
             return;

crates/horizon-client/src/game/station_control.rs

@@ -10,7 +10,7 @@ pub(super) const HELP: &[&str] = &[
     "use X Y Z                      open the block's menu as if right-clicked",
     "click-slot ID [right] [shift]  click a menu slot (0-35 inventory, 300+ container, 600+ station, 650 result)",
     "click-gui X Y [right] [shift]  click at GUI pixel X Y relative to the menu's top-left corner",
-    "book [next|back|take|done]     the open book or lectern: its page, or press one of its buttons",
+    "book [next|back|take|sign|done] the open book or lectern: its page, or press one of its buttons",
     "type TEXT | type-back          type into the anvil name box / delete one character",
     "enchant ID LEVEL               enchant the held item (books store the enchantment)",
     "potion ITEM POTION             give a potion item (potion, splash_potion, lingering_potion, tipped_arrow)",

crates/horizon-client/src/game/wind.rs

@@ -22,6 +22,14 @@ const PLAYER_KNOCKBACK: f32 = 1.22;
 /// `BreezeWindCharge.RADIUS`.
 const BREEZE_RADIUS: f32 = 3.0;
 
+/// A burst `wind_burst` puts off until a guest's turn is over.
+pub(super) struct Burst {
+    center: [f64; 3],
+    radius: f32,
+    multiplier: f32,
+    breeze: bool,
+    wind_charge: bool,
+}
 /// `Projectile.deflect` with `ProjectileDeflection.REVERSE`.
 pub(super) fn reverse(p: &mut Projectile, jitter: f32) {
     p.velocity = Vec3::new(
@@ -196,7 +204,9 @@ impl Game<'_> {
         set.into_iter().collect()
     }
     /// `ServerExplosion.hurtEntities` for a calculator that damages nothing:
-    /// knockback scaled by distance, exposure and the multiplier.
+    /// knockback scaled by distance, exposure and the multiplier. Returns the
+    /// guests it pushed and by how much (`hitPlayers`), which their clients
+    /// apply from the burst's packet.
     fn wind_knockback(
         &mut self,
         center: [f64; 3],
@@ -204,7 +214,7 @@ impl Game<'_> {
         multiplier: f32,
         wind_charge: bool,
         blocklike: bool,
-    ) {
+    ) -> Vec<(u32, [f64; 3])> {
         let diameter = f64::from(radius * 2.0);
         let distance = |p: [f64; 3]| {
             ((p[0] - center[0]).powi(2) + (p[1] - center[1]).powi(2) + (p[2] - center[2]).powi(2))
@@ -223,42 +233,30 @@ impl Game<'_> {
                 [d[0] / l, d[1] / l, d[2] / l]
             }
         };
-        let multiplier = f64::from(multiplier);
-        // The player (not a spectator; a flying creative player takes none).
-        if let Some(p) = self.player.as_ref()
-            && !self.spectator()
-        {
-            let feet = [p.position.x, p.position.y, p.position.z];
-            let dist = distance(feet) / diameter;
-            let flying = self.creative && p.flying;
-            if dist <= 1.0 && !flying {
-                let w = f64::from(p.dimensions.width) / 2.0;
-                let h = f64::from(p.dimensions.height);
-                let eye = [
-                    feet[0],
-                    feet[1] + f64::from(p.dimensions.eye_height),
-                    feet[2],
-                ];
-                let exposure = self.seen_percent(
-                    center,
-                    [feet[0] - w, feet[1], feet[2] - w],
-                    [feet[0] + w, feet[1] + h, feet[2] + w],
-                );
-                let power = (1.0 - dist) * f64::from(exposure) * multiplier;
-                let dir = direction(eye);
-                if let Some(p) = self.player.as_mut() {
-                    p.velocity = Vec3::new(
-                        p.velocity.x + dir[0] * power,
-                        p.velocity.y + dir[1] * power,
-                        p.velocity.z + dir[2] * power,
-                    );
-                    // ServerPlayer.onExplosionHit: a wind charge's burst cancels the
-                    // fall; any other burst ends the grace of the last impulse.
-                    let at = p.position;
-                    p.impulse.set_ignore_fall_damage(wind_charge, Some(at));
+        // The player, then every other player in the level (LAN guests),
+        // each swapped in as the player. In a guest's turn (a mace's wind
+        // burst) the player is that guest.
+        let own = self.wind_push_player(center, radius, multiplier, wind_charge);
+        let mut pushed: Vec<_> = self.lan_acting.zip(own).into_iter().collect();
+        if let Some(mut host) = self.lan.take() {
+            let guests: Vec<u32> = host
+                .hub
+                .guests
+                .iter()
+                .filter(|g| host.hub.here(g) && g.loaded && !g.dead)
+                .map(|g| g.conn)
+                .collect();
+            for conn in guests {
+                let push = self.as_guest(&mut host, conn, |g| {
+                    g.wind_push_player(center, radius, multiplier, wind_charge)
+                });
+                if let Some(Some(push)) = push {
+                    pushed.push((conn, push));
                 }
             }
+            self.lan = Some(host);
         }
+        let multiplier = f64::from(multiplier);
         let mut mobs = std::mem::take(&mut self.mobs);
         for m in mobs.iter_mut().filter(|m| m.alive()) {
             let feet = [m.position.x, m.position.y, m.position.z];
@@ -351,6 +349,67 @@ impl Game<'_> {
             push(t.position, &mut t.velocity, self);
         }
         self.tnts = tnts;
+        pushed
+    }
+    /// `ServerExplosion.hurtEntities` for the player (not a spectator, nor a
+    /// creative player flying): the push, less with explosion knockback
+    /// resistance, and `ServerPlayer.onExplosionHit`. Returns the push.
+    fn wind_push_player(
+        &mut self,
+        center: [f64; 3],
+        radius: f32,
+        multiplier: f32,
+        wind_charge: bool,
+    ) -> Option<[f64; 3]> {
+        if self.spectator() {
+            return None;
+        }
+        let resistance = self
+            .player
+            .as_mut()
+            .and_then(|p| p.attribute("minecraft:explosion_knockback_resistance").ok())
+            .unwrap_or(0.0);
+        let creative = self.creative;
+        let p = self.player.as_ref()?;
+        let feet = [p.position.x, p.position.y, p.position.z];
+        let dist = ((feet[0] - center[0]).powi(2)
+            + (feet[1] - center[1]).powi(2)
+            + (feet[2] - center[2]).powi(2))
+        .sqrt()
+            / f64::from(radius * 2.0);
+        if dist > 1.0 || creative && p.flying {
+            return None;
+        }
+        let w = f64::from(p.dimensions.width) / 2.0;
+        let h = f64::from(p.dimensions.height);
+        let eye = [
+            feet[0] - center[0],
+            feet[1] + f64::from(p.dimensions.eye_height) - center[1],
+            feet[2] - center[2],
+        ];
+        let exposure = self.seen_percent(
+            center,
+            [feet[0] - w, feet[1], feet[2] - w],
+            [feet[0] + w, feet[1] + h, feet[2] + w],
+        );
+        let power = (1.0 - dist) * f64::from(exposure) * f64::from(multiplier) * (1.0 - resistance);
+        let l = (eye[0] * eye[0] + eye[1] * eye[1] + eye[2] * eye[2]).sqrt();
+        let push = if l < 1.0e-5 {
+            [0.0; 3]
+        } else {
+            eye.map(|d| d / l * power)
+        };
+        let p = self.player.as_mut()?;
+        p.velocity = Vec3::new(
+            p.velocity.x + push[0],
+            p.velocity.y + push[1],
+            p.velocity.z + push[2],
+        );
+        // ServerPlayer.onExplosionHit: a wind charge's burst cancels the
+        // fall; any other burst ends the grace of the last impulse.
+        let at = p.position;
+        p.impulse.set_ignore_fall_damage(wind_charge, Some(at));
+        Some(push)
     }
     /// The burst: knockback, the blocks that react, the gust and the sound.
     pub(super) fn wind_burst(
@@ -361,13 +420,27 @@ impl Game<'_> {
         breeze: bool,
         wind_charge: bool,
     ) -> Result<()> {
+        // In a guest's turn (their charge landing, their mace's burst) the
+        // host holds the other players (`as_guest`): the burst waits for the
+        // turn to end so that it reaches every player, the guest too.
+        if self.lan_acting.is_some() && self.lan.is_none() {
+            self.creatures.wind_bursts.push(Burst {
+                center,
+                radius,
+                multiplier,
+                breeze,
+                wind_charge,
+            });
+            return Ok(());
+        }
         // ServerExplosion.explode: the blast is heard first.
         let ctx = horizon_client::sculk::Context::default();
         self.post_game_event("minecraft:explode", center, ctx);
         let mut targets = self.wind_positions(center, radius);
         // ServerExplosion.shouldAffectBlocklikeEntities
         let blocklike = !breeze && !wind_charge && self.ui.rules.bool("mob_griefing");
-        self.wind_knockback(center, radius, multiplier, wind_charge, blocklike);
+        let pushed = self.wind_knockback(center, radius, multiplier, wind_charge, blocklike);
+        let block_count = targets.len();
         // Explosion.canTriggerBlocks: a breeze's charge needs mob griefing.
         if !breeze || self.ui.rules.bool("mob_griefing") {
             // Util.shuffle(list, level.random)
@@ -396,6 +469,14 @@ impl Game<'_> {
         };
         self.particles
             .add(&ParticleOptions::simple(ty), center, [1.0, 0.0, 0.0]);
+        self.lan_wind_burst(center, radius, sound, block_count, &pushed);
+        Ok(())
+    }
+    /// The bursts guests' turns put off.
+    pub(super) fn flush_wind_bursts(&mut self) -> Result<()> {
+        for b in std::mem::take(&mut self.creatures.wind_bursts) {
+            self.wind_burst(b.center, b.radius, b.multiplier, b.breeze, b.wind_charge)?;
+        }
         Ok(())
     }
     /// `BlockBehaviour.onExplosionHit` for `TRIGGER_BLOCK`: doors, gates,

crates/horizon-client/src/gfx.rs

@@ -65,7 +65,8 @@ mod arena;
 mod cull;
 mod end_sky;
 mod flat;
-mod java_stages;
+pub(crate) mod java_stages;
+pub(crate) mod java_terrain;
 pub mod lightning;
 mod lod;
 mod occlusion;
@@ -491,6 +492,15 @@ pub struct Renderer {
     world_post: world_post::Post,
     /// The selected shader pack's stages (Horizon setting; none by default).
     pack: Option<Pack>,
+    /// A Java pack's terrain programs (`gfx/java_terrain.rs`): their page
+    /// groups' layout, the glue's table, each arena page's group.
+    java_page_layout: wgpu::BindGroupLayout,
+    /// The device renders to and filters 16-bit normalized formats.
+    java_norm16: bool,
+    java_table: Option<wgpu::Buffer>,
+    java_pages: Vec<Option<(wgpu::Buffer, wgpu::BindGroup)>>,
+    /// The sprite layers and mip levels `animate` wrote this frame.
+    animated: Vec<(u32, u32)>,
     pub hud: HudRenderer,
     /// Vanilla's menu background blur, made on first use.
     menu_blur: Option<crate::menu_blur::MenuBlur>,
@@ -839,7 +849,10 @@ async fn open_device(
             | cull::Cull::features(&adapter)
             | (adapter.features()
                 & (wgpu::Features::INDIRECT_FIRST_INSTANCE
-                    | wgpu::Features::MAPPABLE_PRIMARY_BUFFERS));
+                    | wgpu::Features::MAPPABLE_PRIMARY_BUFFERS
+                    // Java shader packs' 16-bit colour targets.
+                    | wgpu::Features::TEXTURE_FORMAT_16BIT_NORM
+                    | wgpu::Features::TEXTURE_ADAPTER_SPECIFIC_FORMAT_FEATURES));
         let driver = format!("{} {}", info.driver, info.driver_info);
         startup_step(format_args!(
             "requesting the device (driver {}) with features [{features}] and the adapter's \
@@ -1369,8 +1382,10 @@ impl Renderer {
                         sample_count: 1,
                         dimension: wgpu::TextureDimension::D2,
                         format: wgpu::TextureFormat::Rgba8Unorm,
+                        // COPY_SRC: animated sprites into a Java pack's atlas.
                         usage: wgpu::TextureUsages::TEXTURE_BINDING
                             | wgpu::TextureUsages::COPY_DST
+                            | wgpu::TextureUsages::COPY_SRC
                             | wgpu::TextureUsages::STORAGE_BINDING,
                         view_formats: &[],
                     },
@@ -2214,6 +2229,8 @@ impl Renderer {
             std::mem::size_of::<TerrainVertex>() as u64,
             1 << 20,
         );
+        let java_page_layout = java_terrain::page_layout(&device);
+        let java_norm16 = java_terrain::norm16_targets(&adapter, &device);
         // Sections as one index list per frame where multi-draw is emulated.
         let flat = flat::wanted(&adapter, &device).then(|| {
             let buffers = [Some(wgpu::VertexBufferLayout {
@@ -2414,6 +2431,11 @@ impl Renderer {
             occlusion: occlusion::Occlusion::new(crate::chunk::MIN_Y, crate::chunk::HEIGHT / 16),
             world_post,
             pack: None,
+            java_page_layout,
+            java_norm16,
+            java_table: None,
+            java_pages: Vec::new(),
+            animated: Vec::new(),
             hud,
             menu_blur: None,
             info,
@@ -2722,6 +2744,18 @@ impl Renderer {
         base: u32,
         first: u32,
         count: u32,
+    ) {
+        self.draw_sections_with(pass, indirect, base, first, count, |_, _| {});
+    }
+    /// [`Self::draw_sections`]; `page` binds what else a page's draws need.
+    fn draw_sections_with(
+        &self,
+        pass: &mut wgpu::RenderPass<'_>,
+        indirect: &wgpu::Buffer,
+        base: u32,
+        first: u32,
+        count: u32,
+        page_group: impl Fn(&mut wgpu::RenderPass<'_>, u32),
     ) {
         let (mut i, end) = (first as usize, (first + count) as usize);
         while i < end {
@@ -2731,6 +2765,7 @@ impl Renderer {
                 .take_while(|&&p| p == (page, index_page))
                 .count();
             pass.set_vertex_buffer(0, self.arena.buffer(page).slice(..));
+            page_group(pass, page);
             let indices = index_page.map_or(&self.indices, |p| self.sorted_indices.buffer(p));
             pass.set_index_buffer(indices.slice(..), wgpu::IndexFormat::Uint32);
             if self.multi_draw {
@@ -2744,6 +2779,88 @@ impl Renderer {
             i += run;
         }
     }
+    /// Horizon's terrain, solid or `translucent`, with a Java pack's
+    /// geometry pipelines (`java_terrain::DrawTerrain`): the frame's flat
+    /// draws or its section draws, each page with its group 3.
+    fn draw_java_terrain(
+        &self,
+        pass: &mut wgpu::RenderPass<'_>,
+        translucent: bool,
+        pipelines: &java_terrain::TerrainPipelines,
+        flat_frame: bool,
+        draws: [u32; 2],
+    ) {
+        let page = |pass: &mut wgpu::RenderPass<'_>, page: u32| {
+            if let Some(Some((_, group))) = self.java_pages.get(page as usize) {
+                pass.set_bind_group(3, group, &[]);
+            }
+        };
+        pass.set_bind_group(2, pipelines.group, &[]);
+        match (self.flat.as_ref().filter(|_| flat_frame), pipelines.flat) {
+            (Some(flat), Some(pipeline)) => {
+                pass.set_pipeline(pipeline);
+                let calls = if translucent {
+                    &flat.calls[flat.solid_calls..]
+                } else {
+                    &flat.calls[..flat.solid_calls]
+                };
+                flat.draw(pass, calls, |p| self.arena.buffer(p), page);
+            }
+            (Some(_), None) => {}
+            (None, _) => {
+                pass.set_pipeline(pipelines.instanced);
+                pass.set_index_buffer(self.indices.slice(..), wgpu::IndexFormat::Uint32);
+                pass.set_vertex_buffer(1, self.instances.slice(..));
+                let [solid, translucent_draws] = draws;
+                let (first, count) = if translucent {
+                    (solid, translucent_draws)
+                } else {
+                    (0, solid)
+                };
+                self.draw_sections_with(pass, &self.indirect, 0, first, count, page);
+            }
+        }
+    }
+    /// Each arena page's group for a Java pack's terrain programs: its
+    /// vertices and the glue's table.
+    fn prepare_java_pages(&mut self) {
+        let Some(table) = &self.java_table else {
+            return;
+        };
+        let count = self.arena.page_count() as usize;
+        self.java_pages.resize_with(count, || None);
+        let limit = self.device.limits().max_storage_buffer_binding_size;
+        for page in 0..count {
+            if !self.arena.has_page(page as u32) {
+                self.java_pages[page] = None;
+                continue;
+            }
+            let buffer = self.arena.buffer(page as u32);
+            if matches!(&self.java_pages[page], Some((b, _)) if b == buffer) {
+                continue;
+            }
+            let size = buffer.size().min(limit / 4 * 4);
+            let group = self.device.create_bind_group(&wgpu::BindGroupDescriptor {
+                label: Some("Java shader pack terrain page"),
+                layout: &self.java_page_layout,
+                entries: &[
+                    wgpu::BindGroupEntry {
+                        binding: 0,
+                        resource: wgpu::BindingResource::Buffer(wgpu::BufferBinding {
+                            buffer,
+                            offset: 0,
+                            size: std::num::NonZeroU64::new(size),
+                        }),
+                    },
+                    wgpu::BindGroupEntry {
+                        binding: 1,
+                        resource: table.as_entire_binding(),
+                    },
+                ],
+            });
+            self.java_pages[page] = Some((buffer.clone(), group));
+        }
+    }
     fn release_section(&mut self, key: SectionKey) {
         if let Some(s) = self.sections.remove(key) {
             self.release_mesh(s);
@@ -2827,9 +2944,29 @@ impl Renderer {
         }
     }
     /// Run `pack`'s stages over the world from now on (`None`: no pack, the
-    /// vanilla frame). On error the previous pack stays.
-    pub fn set_shader_pack(&mut self, pack: Option<&crate::shader_pack::ShaderPack>) -> Result<()> {
+    /// vanilla frame). On error the previous pack stays. `sprite_layers`
+    /// names the block sprites, for a Java pack's `block.properties`.
+    pub fn set_shader_pack(
+        &mut self,
+        pack: Option<&crate::shader_pack::ShaderPack>,
+        sprite_layers: &std::collections::BTreeMap<String, u32>,
+    ) -> Result<()> {
         let format = self.config.format.remove_srgb_suffix();
+        let layouts = java_stages::GeometryLayouts {
+            flat: self.flat.as_ref().map(|f| f.draw_layout()),
+            page: &self.java_page_layout,
+        };
+        let table = pack.and_then(|p| p.java.as_ref()).map(|java| {
+            let table = java_terrain::table(sprite_layers, &java.block_ids);
+            wgpu::util::DeviceExt::create_buffer_init(
+                &self.device,
+                &wgpu::util::BufferInitDescriptor {
+                    label: Some("Java shader pack terrain table"),
+                    contents: bytemuck::cast_slice(&table),
+                    usage: wgpu::BufferUsages::STORAGE | wgpu::BufferUsages::COPY_DST,
+                },
+            )
+        });
         self.pack = match pack {
             Some(pack) => Some(match &pack.java {
                 Some(java) => Pack::Java(java_stages::JavaStages::new(
@@ -2838,6 +2975,8 @@ impl Renderer {
                     format,
                     &pack.id,
                     java,
+                    &layouts,
+                    self.java_norm16,
                 )?),
                 None => Pack::Horizon(pack_stages::PackStages::new(
                     &self.device,
@@ -2848,6 +2987,8 @@ impl Renderer {
             }),
             None => None,
         };
+        self.java_table = table;
+        self.java_pages.clear();
         Ok(())
     }
     /// The folder name of the pack `set_shader_pack` gave.
@@ -2988,6 +3129,15 @@ impl Renderer {
     }
     fn animate(&mut self, encoder: &mut wgpu::CommandEncoder, tick: u64) {
         self.animations.animate(encoder, &mut self.uploads, tick);
+        // A Java pack's atlas copies what changed, every level.
+        let levels = self.mip_levels;
+        self.animated.clear();
+        self.animated.extend(
+            self.animations
+                .changed
+                .iter()
+                .flat_map(|&layer| (0..levels).map(move |level| (layer, level))),
+        );
     }
     pub fn render(&mut self, frame: &Frame) -> Result<bool> {
         let rendered = self.draw_frame(frame);
@@ -3272,6 +3422,12 @@ impl Renderer {
         let eye = (frame.bob * crate::camera::view_matrix(frame.yaw, frame.pitch))
             .inverse()
             .transform_point3(Vec3::ZERO);
+        // A Java pack that draws the terrain (`gfx/java_terrain.rs`): the
+        // world pass leaves it out, and occlusion culling (which tests
+        // against its depth) is off.
+        let java_terrain = !frame.title
+            && self.java_table.is_some()
+            && matches!(&self.pack, Some(Pack::Java(j)) if j.draws_terrain(frame.shader.dimension));
         // Occlusion culling leaves the sections its last result did not see
         // to phase 2, after the others, with instance counts of 0. Whether
         // the frame has draws enough goes by the last one's.
@@ -3279,7 +3435,11 @@ impl Renderer {
             .cull
             .as_mut()
             .filter(|c| {
-                self.cull_on && !frame.title && self.multi_draw && self.section_draws >= c.min_draws
+                self.cull_on
+                    && !frame.title
+                    && self.multi_draw
+                    && self.section_draws >= c.min_draws
+                    && !java_terrain
             })
             .and_then(|cull| cull.begin(&self.device).then_some(cull));
         self.phase2_draws.clear();
@@ -3729,6 +3889,14 @@ impl Renderer {
                 bytemuck::cast_slice(&self.draws),
             );
         }
+        if java_terrain {
+            self.prepare_java_pages();
+            if let Some(table) = &self.java_table {
+                let nether = i32::from(frame.shader.dimension == -1);
+                self.queue
+                    .write_buffer(table, 4, bytemuck::bytes_of(&nether));
+            }
+        }
         let view_target = target_texture.create_view(&wgpu::TextureViewDescriptor {
             format: Some(self.config.format.remove_srgb_suffix()),
             ..Default::default()
@@ -3890,6 +4058,7 @@ impl Renderer {
                 }
             }
             match self.flat.as_ref().filter(|_| flat_frame) {
+                _ if java_terrain => {}
                 Some(flat) => {
                     pass.set_pipeline(&flat.solid);
                     let vertices = |p| self.arena.buffer(p);
@@ -3897,7 +4066,12 @@ impl Renderer {
                         // As below: phase 1, the test, then phase 2's draws
                         // that the test saw, copied after it.
                         Some(cull) => {
-                            flat.draw(&mut pass, &flat.calls[..flat.phase1_calls], vertices);
+                            flat.draw(
+                                &mut pass,
+                                &flat.calls[..flat.phase1_calls],
+                                vertices,
+                                |_, _| {},
+                            );
                             cull.test(&mut pass);
                             drop(pass);
                             cull.test_pass(&mut encoder);
@@ -3912,7 +4086,12 @@ impl Renderer {
                             pass.set_pipeline(&flat.solid);
                             flat.draw_phase2(&mut pass, vertices);
                         }
-                        None => flat.draw(&mut pass, &flat.calls[..flat.solid_calls], vertices),
+                        None => flat.draw(
+                            &mut pass,
+                            &flat.calls[..flat.solid_calls],
+                            vertices,
+                            |_, _| {},
+                        ),
                     }
                     pass.set_bind_group(0, &self.group, &[]);
                     pass.set_index_buffer(self.indices.slice(..), wgpu::IndexFormat::Uint32);
@@ -4041,11 +4220,15 @@ impl Renderer {
                 pass.set_bind_group(0, &self.group, &[]);
             }
             match self.flat.as_ref().filter(|_| flat_frame) {
+                _ if java_terrain => {}
                 Some(flat) => {
                     pass.set_pipeline(&flat.translucent);
-                    flat.draw(&mut pass, &flat.calls[flat.solid_calls..], |p| {
-                        self.arena.buffer(p)
-                    });
+                    flat.draw(
+                        &mut pass,
+                        &flat.calls[flat.solid_calls..],
+                        |p| self.arena.buffer(p),
+                        |_, _| {},
+                    );
                     pass.set_bind_group(0, &self.group, &[]);
                     pass.set_index_buffer(self.indices.slice(..), wgpu::IndexFormat::Uint32);
                 }
@@ -4120,10 +4303,26 @@ impl Renderer {
                 frame.shader.rain,
             );
         }
-        if let (true, Some((color, depth)), Some(size), Some(stages)) =
-            (pack, &scaled, self.world_post.size(), self.pack.as_mut())
+        if pack
+            && let (Some((color, depth)), Some(size)) = (&scaled, self.world_post.size())
+            && let Some(mut stages) = self.pack.take()
         {
-            let output = match stages {
+            // The pack's terrain programs draw with the frame's draws.
+            let draws = [solid_draws, translucent_draws];
+            let draw = |render: &mut wgpu::RenderPass<'_>,
+                        translucent: bool,
+                        pipelines: &java_terrain::TerrainPipelines| {
+                self.draw_java_terrain(render, translucent, pipelines, flat_frame, draws);
+            };
+            let world = java_terrain::JavaWorld {
+                sprites: &self.sprite_textures,
+                split: sprite_split(),
+                levels: self.mipmaps,
+                animated: &self.animated,
+                lightmap: &self.lightmap_view,
+                draw: &draw,
+            };
+            let output = match &mut stages {
                 Pack::Horizon(stages) => stages.run(
                     &self.device,
                     &self.queue,
@@ -4149,10 +4348,12 @@ impl Renderer {
                         sun_angle: frame.sky.sun_angle,
                         moon_angle: frame.sky.moon_angle,
                     },
+                    java_terrain.then_some(&world),
                 ),
             };
             self.world_post
                 .finish_with(&mut encoder, &view_target, output);
+            self.pack = Some(stages);
         } else if scaled.is_some() {
             self.world_post.finish(&mut encoder, &view_target);
         }

crates/horizon-client/src/gfx/animate.rs

@@ -51,6 +51,9 @@ pub(super) struct SpriteAnimator {
     pipeline: wgpu::ComputePipeline,
     /// Edge of the arrays' layers.
     size: u32,
+    /// The sprite layers (across the arrays) the last `animate` rewrote, at
+    /// every mip level: a Java pack's atlas copies them.
+    pub changed: Vec<u32>,
 }
 
 impl SpriteAnimator {
@@ -205,6 +208,7 @@ impl SpriteAnimator {
             jobs,
             pipeline,
             size,
+            changed: Vec::new(),
         }
     }
 
@@ -216,6 +220,7 @@ impl SpriteAnimator {
         uploads: &mut Uploads,
         tick: u64,
     ) {
+        self.changed.clear();
         if self.collect(tick) == 0 {
             return;
         }
@@ -251,6 +256,7 @@ impl SpriteAnimator {
                 continue;
             }
             sprite.shown = Some(blend);
+            self.changed.push(sprite.animation.layer);
             let job = [
                 sprite.layer,
                 sprite.frames[blend.frame],

crates/horizon-client/src/gfx/arena.rs

@@ -65,8 +65,11 @@ pub struct Arena {
 }
 
 impl Arena {
+    /// Vertices; also storage, which a Java shader pack's terrain programs
+    /// read a quad's corners from (`gfx/java_terrain.rs`).
     pub fn new(device: &wgpu::Device, stride: u64, capacity: u64) -> Self {
-        Self::with_usage(device, stride, capacity, wgpu::BufferUsages::VERTEX)
+        let usage = wgpu::BufferUsages::VERTEX | wgpu::BufferUsages::STORAGE;
+        Self::with_usage(device, stride, capacity, usage)
     }
     /// Sorted translucent indices; `storage` when compute passes read them.
     pub fn indices(device: &wgpu::Device, capacity: u64, storage: bool) -> Self {
@@ -145,6 +148,10 @@ impl Arena {
     pub fn page_vertices(&self) -> u64 {
         self.page_limit
     }
+    /// One past the last page index.
+    pub fn page_count(&self) -> u32 {
+        self.pages.len() as u32
+    }
     pub fn has_page(&self, page: u32) -> bool {
         self.pages.get(page as usize).is_some_and(Option::is_some)
     }

crates/horizon-client/src/gfx/flat.rs

@@ -640,17 +640,26 @@ impl Flat {
         pass.set_bind_group(0, group, &[]);
         pass.dispatch_workgroups((*count).min(GROUP_LIMIT), count.div_ceil(GROUP_LIMIT), 1);
     }
+    /// The bind group layout of the draws' group 1 (block slots, slot
+    /// origins).
+    pub fn draw_layout(&self) -> &wgpu::BindGroupLayout {
+        &self.draw_layout
+    }
+
     /// Draws `calls` with a flat pipeline set and `vertices` giving each
-    /// page's vertex buffer.
+    /// page's vertex buffer; `page` binds what else a page's draws need (a
+    /// Java pack's terrain reads the page's vertices).
     pub fn draw<'a>(
         &self,
         pass: &mut wgpu::RenderPass<'_>,
         calls: &[Call],
         vertices: impl Fn(u32) -> &'a wgpu::Buffer,
+        page: impl Fn(&mut wgpu::RenderPass<'_>, u32),
     ) {
         pass.set_index_buffer(self.indices.slice(..), wgpu::IndexFormat::Uint32);
         for call in calls {
             self.bind_page(pass, call.page, &vertices);
+            page(pass, call.page);
             pass.draw_indexed(call.first..call.first + call.count, 0, 0..1);
         }
     }

crates/horizon-client/src/gfx/java_terrain.rs

@@ -0,0 +1,645 @@
+//! Horizon's terrain drawn with a Java pack's `gbuffers_terrain` and
+//! `gbuffers_water` (docs/shader-packs.md). The pack's vertex program runs
+//! after a glue that rebuilds what Iris would feed it from Horizon's
+//! `TerrainVertex`: the camera-relative position, the quad's normal and
+//! tangent (from its four corners, read from the arena page as storage),
+//! the colour without vanilla's directional shade, the lightmap
+//! coordinates, the sprite's place in a block atlas laid out from Horizon's
+//! sprite arrays, and `mc_Entity` from the pack's `block.properties`, by
+//! sprite name.
+use horizon_shaderpack::translate::Geometry;
+use std::collections::BTreeMap;
+
+/// `TerrainVertex` in 32-bit words.
+const VERTEX_WORDS: u32 = 6;
+
+/// The glue's declarations and `hz_vertex`; `HZ_ORIGIN_DECL` and
+/// `HZ_ORIGIN` are the variant's (instanced or flat draws).
+const GLUE: &str = r#"
+layout(location = 0) in vec3 hz_position;
+layout(location = 1) in uvec2 hz_uv;
+layout(location = 2) in uint hz_layer;
+layout(location = 3) in vec4 hz_color;
+layout(location = 4) in uvec2 hz_light;
+HZ_ORIGIN_DECL
+layout(std430, set = 3, binding = 0) readonly buffer HzVertices { uint hz_vertices[]; };
+// [0]: atlas columns, [1]: 1 in the Nether, then each sprite layer's block id.
+layout(std430, set = 3, binding = 1) readonly buffer HzTable { int hz_table[]; };
+vec4 hz_pos;
+vec3 hz_normal;
+vec4 hz_tangent;
+vec4 hz_tint;
+vec2 hz_atlas;
+vec2 hz_mid;
+vec2 hz_lightmap;
+float hz_block;
+vec3 hz_mid_block;
+vec3 hz_corner(uint v) {
+    uint b = v * HZ_WORDSu;
+    return vec3(uintBitsToFloat(hz_vertices[b]), uintBitsToFloat(hz_vertices[b + 1u]),
+        uintBitsToFloat(hz_vertices[b + 2u]));
+}
+vec2 hz_corner_uv(uint v) {
+    uint w = hz_vertices[v * HZ_WORDSu + 3u];
+    return vec2(float(w & 65535u), float(w >> 16u));
+}
+void hz_vertex() {
+    vec4 origin = HZ_ORIGIN;
+    hz_pos = vec4(hz_position + origin.xyz, 1.0);
+    // The quad's corners: quads are four vertices from a multiple of four.
+    uint q = uint(gl_VertexIndex) & 4294967292u;
+    vec3 p0 = hz_corner(q);
+    vec3 e1 = hz_corner(q + 1u) - p0;
+    vec3 e2 = hz_corner(q + 2u) - p0;
+    vec3 n = cross(e1, e2);
+    if (dot(n, n) < 1e-12) {
+        n = cross(e2, hz_corner(q + 3u) - p0);
+    }
+    hz_normal = dot(n, n) > 0.0 ? normalize(n) : vec3(0.0, 1.0, 0.0);
+    vec2 t0 = hz_corner_uv(q);
+    vec2 d1 = hz_corner_uv(q + 1u) - t0;
+    vec2 d2 = hz_corner_uv(q + 2u) - t0;
+    float s = d1.x * d2.y - d2.x * d1.y < 0.0 ? -1.0 : 1.0;
+    vec3 t = (e1 * d2.y - e2 * d1.y) * s;
+    vec3 b = (e2 * d1.x - e1 * d2.x) * s;
+    t = t - hz_normal * dot(hz_normal, t);
+    t = dot(t, t) > 0.0 ? normalize(t) : vec3(1.0, 0.0, 0.0);
+    hz_tangent = vec4(t, dot(cross(hz_normal, t), b) < 0.0 ? -1.0 : 1.0);
+    // Iris turns vanilla's directional shade off: undo it on axis faces.
+    vec3 a = abs(hz_normal);
+    bool nether = hz_table[1] != 0;
+    float shade = 1.0;
+    if (a.y > 0.999) {
+        shade = nether ? 0.9 : (hz_normal.y > 0.0 ? 1.0 : 0.5);
+    } else if (a.z > 0.999) {
+        shade = 0.8;
+    } else if (a.x > 0.999) {
+        shade = 0.6;
+    }
+    hz_tint = vec4(min(hz_color.rgb / shade, vec3(1.0)), hz_color.a);
+    // The sprite's cell in the atlas, columns of square cells.
+    int layer = int(hz_layer & 16383u);
+    int cols = max(hz_table[0], 1);
+    vec2 cell = vec2(float(layer % cols), float(layer / cols));
+    vec2 uv = clamp(vec2(hz_uv) * origin.w, 0.0, 1.0);
+    hz_atlas = (cell + uv) / float(cols);
+    hz_mid = (cell + 0.5) / float(cols);
+    // Vanilla's UV2: block light, then sky light, 0..240.
+    hz_lightmap = vec2(float(hz_light.y), float(hz_light.x));
+    hz_block = float(hz_table[2 + layer]);
+    hz_mid_block = (floor(hz_position - hz_normal * 0.01) + 0.5 - hz_position) * 64.0;
+}
+"#;
+
+/// The glue of one draw path: instanced section draws (the origin is an
+/// instance attribute) or flat ones (`gfx/flat.rs`: from the block's slot).
+pub fn glue(flat: bool, alpha_test: Option<f32>) -> Geometry {
+    let (decl, origin) = if flat {
+        (
+            "layout(std430, set = 1, binding = 0) readonly buffer HzBlockSlots { uint hz_block_slots[]; };\n\
+             layout(std430, set = 1, binding = 1) readonly buffer HzSlotOrigins { vec4 hz_slot_origins[]; };",
+            "hz_slot_origins[hz_block_slots[uint(gl_VertexIndex) >> 8u]]",
+        )
+    } else {
+        ("layout(location = 5) in vec4 hz_origin;", "hz_origin")
+    };
+    let vertex_glue = GLUE
+        .replace("HZ_ORIGIN_DECL", decl)
+        .replace("HZ_ORIGIN", origin)
+        .replace("HZ_WORDS", &VERTEX_WORDS.to_string());
+    let lightmap = "vec4(hz_lightmap, 0.0, 1.0)";
+    let attributes: BTreeMap<String, String> = [
+        ("iris_Vertex", "hz_pos"),
+        ("vaPosition", "hz_pos"),
+        ("iris_Normal", "vec4(hz_normal, 0.0)"),
+        ("vaNormal", "vec4(hz_normal, 0.0)"),
+        ("iris_Color", "hz_tint"),
+        ("vaColor", "hz_tint"),
+        ("iris_MultiTexCoord0", "vec4(hz_atlas, 0.0, 1.0)"),
+        ("vaUV0", "vec4(hz_atlas, 0.0, 1.0)"),
+        ("iris_MultiTexCoord1", lightmap),
+        ("iris_MultiTexCoord2", lightmap),
+        ("vaUV2", lightmap),
+        // OverlayTexture.NO_OVERLAY.
+        ("vaUV1", "vec4(0.0, 10.0, 0.0, 0.0)"),
+        ("mc_Entity", "vec4(hz_block, -1.0, 0.0, 0.0)"),
+        ("mc_midTexCoord", "vec4(hz_mid, 0.0, 1.0)"),
+        ("at_tangent", "hz_tangent"),
+        ("at_midBlock", "vec4(hz_mid_block, 0.0)"),
+    ]
+    .into_iter()
+    .map(|(k, v)| (k.to_owned(), v.to_owned()))
+    .collect();
+    Geometry {
+        vertex_glue,
+        attributes,
+        alpha_test,
+    }
+}
+
+/// The glue's table: atlas columns, the Nether flag, then each sprite
+/// layer's block id from `block.properties` (-1 for blocks it doesn't
+/// list, as Iris).
+pub fn table(sprite_layers: &BTreeMap<String, u32>, block_ids: &BTreeMap<String, i32>) -> Vec<i32> {
+    let layers = sprite_layers.values().max().map_or(0, |&m| m as usize + 1);
+    let mut out = vec![-1; layers + 2];
+    out[0] = atlas_columns(layers as u32) as i32;
+    out[1] = 0;
+    for (name, &layer) in sprite_layers {
+        if let Some(id) = horizon_shaderpack::properties::sprite_block_id(name, block_ids) {
+            out[layer as usize + 2] = id;
+        }
+    }
+    out
+}
+
+/// The atlas's columns (and rows) of sprite cells for `layers` sprites.
+pub fn atlas_columns(layers: u32) -> u32 {
+    (f64::from(layers.max(1)).sqrt().ceil() as u32).max(1)
+}
+
+/// Whether `device` renders to and filters the 16-bit normalized formats
+/// a Java pack's `RGBA16` targets become (`java_stages::target_format`).
+pub fn norm16_targets(adapter: &wgpu::Adapter, device: &wgpu::Device) -> bool {
+    use wgpu::TextureFormat as F;
+    let wanted = wgpu::Features::TEXTURE_FORMAT_16BIT_NORM
+        | wgpu::Features::TEXTURE_ADAPTER_SPECIFIC_FORMAT_FEATURES;
+    device.features().contains(wanted)
+        && [
+            F::R16Unorm,
+            F::Rg16Unorm,
+            F::Rgba16Unorm,
+            F::R16Snorm,
+            F::Rg16Snorm,
+            F::Rgba16Snorm,
+        ]
+        .into_iter()
+        .all(|f| {
+            let features = adapter.get_texture_format_features(f);
+            features
+                .allowed_usages
+                .contains(wgpu::TextureUsages::RENDER_ATTACHMENT)
+                && features
+                    .flags
+                    .contains(wgpu::TextureFormatFeatureFlags::FILTERABLE)
+        })
+}
+
+/// The bind group layout of a page group: the page's vertices and the glue's
+/// table, read by the vertex stage.
+pub fn page_layout(device: &wgpu::Device) -> wgpu::BindGroupLayout {
+    let storage = |binding| wgpu::BindGroupLayoutEntry {
+        binding,
+        visibility: wgpu::ShaderStages::VERTEX,
+        ty: wgpu::BindingType::Buffer {
+            ty: wgpu::BufferBindingType::Storage { read_only: true },
+            has_dynamic_offset: false,
+            min_binding_size: None,
+        },
+        count: None,
+    };
+    device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+        label: Some("Java shader pack terrain page"),
+        entries: &[storage(0), storage(1)],
+    })
+}
+
+/// Draws Horizon's terrain with a pack's pipelines: the solid layer or the
+/// translucent one. Set by the renderer, which owns the sections.
+pub type DrawTerrain<'a> = dyn Fn(&mut wgpu::RenderPass<'_>, bool, &TerrainPipelines<'_>) + 'a;
+
+/// What the renderer binds to draw with a pack's geometry program: the
+/// pipeline of its draw path and the pack's group (group 2). Group 1 is the
+/// flat path's, group 3 the page's ([`page_layout`]). `flat` is `None` when
+/// the renderer has no flat draws.
+pub struct TerrainPipelines<'a> {
+    pub instanced: &'a wgpu::RenderPipeline,
+    pub flat: Option<&'a wgpu::RenderPipeline>,
+    pub group: &'a wgpu::BindGroup,
+}
+
+/// What a Java pack's geometry reads from the renderer each frame.
+pub struct JavaWorld<'a> {
+    /// The block sprite arrays, [`super::SPRITE_SPLIT`]-layer each.
+    pub sprites: &'a [wgpu::Texture],
+    pub split: u32,
+    /// Mipmap levels the terrain samples.
+    pub levels: u32,
+    /// The sprite layers and mip levels animation rewrote this frame.
+    pub animated: &'a [(u32, u32)],
+    pub lightmap: &'a wgpu::TextureView,
+    pub draw: &'a DrawTerrain<'a>,
+}
+
+const ATLAS: &str = r#"
+struct Atlas { cols: u32, layers: u32, split: u32, pad: u32 }
+@group(0) @binding(0) var<uniform> atlas: Atlas;
+@group(0) @binding(1) var s0: texture_2d_array<f32>;
+@group(0) @binding(2) var s1: texture_2d_array<f32>;
+@group(0) @binding(3) var s2: texture_2d_array<f32>;
+@group(0) @binding(4) var s3: texture_2d_array<f32>;
+@group(0) @binding(5) var s4: texture_2d_array<f32>;
+@group(0) @binding(6) var s5: texture_2d_array<f32>;
+@group(0) @binding(7) var s6: texture_2d_array<f32>;
+@group(0) @binding(8) var s7: texture_2d_array<f32>;
+
+struct Out {
+    @builtin(position) p: vec4f,
+    @location(0) @interpolate(flat) mip: u32,
+}
+
+@vertex
+fn vs(@builtin(vertex_index) i: u32, @builtin(instance_index) mip: u32) -> Out {
+    let uv = vec2f(f32((i << 1u) & 2u), f32(i & 2u));
+    return Out(vec4f(uv * 2.0 - 1.0, 0.0, 1.0), mip);
+}
+
+// Each sprite layer into its cell, at mip level `mip`.
+@fragment
+fn fs(in: Out) -> @location(0) vec4f {
+    let cell = max(textureDimensions(s0, in.mip).x, 1u);
+    let px = vec2u(in.p.xy);
+    let c = px / cell;
+    let layer = c.y * atlas.cols + c.x;
+    if c.x >= atlas.cols || layer >= atlas.layers {
+        return vec4f(0.0);
+    }
+    let at = px % cell;
+    let l = i32(layer % atlas.split);
+    let m = i32(in.mip);
+    switch layer / atlas.split {
+        case 0u: { return textureLoad(s0, at, l, m); }
+        case 1u: { return textureLoad(s1, at, l, m); }
+        case 2u: { return textureLoad(s2, at, l, m); }
+        case 3u: { return textureLoad(s3, at, l, m); }
+        case 4u: { return textureLoad(s4, at, l, m); }
+        case 5u: { return textureLoad(s5, at, l, m); }
+        case 6u: { return textureLoad(s6, at, l, m); }
+        default: { return textureLoad(s7, at, l, m); }
+    }
+}
+"#;
+
+/// Horizon's block sprites as one 2D atlas, as Iris binds `gtexture`:
+/// square cells, [`atlas_columns`] to a row. Drawn from the sprite arrays
+/// once, then animated sprites are copied in as they change.
+pub struct Atlas {
+    texture: wgpu::Texture,
+    pub view: wgpu::TextureView,
+    mips: Vec<wgpu::TextureView>,
+    pipeline: wgpu::RenderPipeline,
+    layout: wgpu::BindGroupLayout,
+    uniform: wgpu::Buffer,
+    /// Layers, sprite size, mip levels it was made for.
+    key: (u32, u32, u32),
+    /// The first sprite array it was drawn from (resource reloads make
+    /// new ones).
+    source: wgpu::Texture,
+    drawn: bool,
+}
+
+impl Atlas {
+    /// The atlas for `world`'s sprites; `None` without any.
+    pub fn new(device: &wgpu::Device, queue: &wgpu::Queue, world: &JavaWorld) -> Option<Self> {
+        let key = Self::key(world)?;
+        let (layers, size, levels) = key;
+        let cols = atlas_columns(layers);
+        let texture = device.create_texture(&wgpu::TextureDescriptor {
+            label: Some("Java shader pack block atlas"),
+            size: wgpu::Extent3d {
+                width: cols * size,
+                height: cols * size,
+                depth_or_array_layers: 1,
+            },
+            mip_level_count: levels,
+            sample_count: 1,
+            dimension: wgpu::TextureDimension::D2,
+            format: wgpu::TextureFormat::Rgba8Unorm,
+            usage: wgpu::TextureUsages::RENDER_ATTACHMENT
+                | wgpu::TextureUsages::TEXTURE_BINDING
+                | wgpu::TextureUsages::COPY_DST,
+            view_formats: &[],
+        });
+        let mips = (0..levels)
+            .map(|level| {
+                texture.create_view(&wgpu::TextureViewDescriptor {
+                    base_mip_level: level,
+                    mip_level_count: Some(1),
+                    ..Default::default()
+                })
+            })
+            .collect();
+        let mut entries = vec![wgpu::BindGroupLayoutEntry {
+            binding: 0,
+            visibility: wgpu::ShaderStages::FRAGMENT,
+            ty: wgpu::BindingType::Buffer {
+                ty: wgpu::BufferBindingType::Uniform,
+                has_dynamic_offset: false,
+                min_binding_size: None,
+            },
+            count: None,
+        }];
+        entries.extend((1..=8).map(|binding| wgpu::BindGroupLayoutEntry {
+            binding,
+            visibility: wgpu::ShaderStages::FRAGMENT,
+            ty: wgpu::BindingType::Texture {
+                sample_type: wgpu::TextureSampleType::Float { filterable: false },
+                view_dimension: wgpu::TextureViewDimension::D2Array,
+                multisampled: false,
+            },
+            count: None,
+        }));
+        let layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+            label: Some("Java shader pack block atlas"),
+            entries: &entries,
+        });
+        let module = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+            label: Some("Java shader pack block atlas"),
+            source: wgpu::ShaderSource::Wgsl(ATLAS.into()),
+        });
+        let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+            label: Some("Java shader pack block atlas"),
+            layout: Some(
+                &device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+                    label: Some("Java shader pack block atlas"),
+                    bind_group_layouts: &[Some(&layout)],
+                    ..Default::default()
+                }),
+            ),
+            vertex: wgpu::VertexState {
+                module: &module,
+                entry_point: Some("vs"),
+                compilation_options: Default::default(),
+                buffers: &[],
+            },
+            primitive: Default::default(),
+            depth_stencil: None,
+            multisample: Default::default(),
+            fragment: Some(wgpu::FragmentState {
+                module: &module,
+                entry_point: Some("fs"),
+                compilation_options: Default::default(),
+                targets: &[Some(wgpu::TextureFormat::Rgba8Unorm.into())],
+            }),
+            multiview_mask: None,
+            cache: None,
+        });
+        let uniform = device.create_buffer(&wgpu::BufferDescriptor {
+            label: Some("Java shader pack block atlas"),
+            size: 16,
+            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
+            mapped_at_creation: false,
+        });
+        queue.write_buffer(
+            &uniform,
+            0,
+            bytemuck::cast_slice(&[cols, layers, world.split.max(1), 0]),
+        );
+        Some(Self {
+            view: texture.create_view(&Default::default()),
+            texture,
+            mips,
+            pipeline,
+            layout,
+            uniform,
+            key,
+            source: world.sprites[0].clone(),
+            drawn: false,
+        })
+    }
+
+    fn key(world: &JavaWorld) -> Option<(u32, u32, u32)> {
+        let first = world.sprites.first()?;
+        let layers = world
+            .sprites
+            .iter()
+            .map(|t| t.depth_or_array_layers())
+            .sum();
+        let levels = (world.levels + 1).min(first.mip_level_count()).max(1);
+        Some((layers, first.width(), levels))
+    }
+
+    /// Whether it was made for `world`'s sprites.
+    pub fn fits(&self, world: &JavaWorld) -> bool {
+        Self::key(world) == Some(self.key) && world.sprites.first() == Some(&self.source)
+    }
+
+    /// Bring it up to date: drawn the first time, then the sprites
+    /// animation rewrote copied into their cells.
+    pub fn update(
+        &mut self,
+        device: &wgpu::Device,
+        encoder: &mut wgpu::CommandEncoder,
+        world: &JavaWorld,
+    ) {
+        if !self.drawn {
+            self.draw(device, encoder, world);
+            self.drawn = true;
+            return;
+        }
+        let (layers, size, levels) = self.key;
+        let cols = atlas_columns(layers);
+        let split = world.split.max(1);
+        for &(layer, level) in world.animated {
+            let Some(array) = world.sprites.get((layer / split) as usize) else {
+                continue;
+            };
+            if level >= levels || layer >= layers {
+                continue;
+            }
+            let edge = (size >> level).max(1);
+            encoder.copy_texture_to_texture(
+                wgpu::TexelCopyTextureInfo {
+                    texture: array,
+                    mip_level: level,
+                    origin: wgpu::Origin3d {
+                        x: 0,
+                        y: 0,
+                        z: layer % split,
+                    },
+                    aspect: wgpu::TextureAspect::All,
+                },
+                wgpu::TexelCopyTextureInfo {
+                    texture: &self.texture,
+                    mip_level: level,
+                    origin: wgpu::Origin3d {
+                        x: (layer % cols) * edge,
+                        y: (layer / cols) * edge,
+                        z: 0,
+                    },
+                    aspect: wgpu::TextureAspect::All,
+                },
+                wgpu::Extent3d {
+                    width: edge,
+                    height: edge,
+                    depth_or_array_layers: 1,
+                },
+            );
+        }
+    }
+
+    /// The atlas's size in pixels (`atlasSize`).
+    pub fn size(&self) -> [u32; 2] {
+        [self.texture.width(), self.texture.height()]
+    }
+
+    /// Draw the sprites into the atlas, every mip level.
+    fn draw(&self, device: &wgpu::Device, encoder: &mut wgpu::CommandEncoder, world: &JavaWorld) {
+        let views: Vec<wgpu::TextureView> = (0..8)
+            .map(|i| {
+                let t = world.sprites.get(i).unwrap_or(&world.sprites[0]);
+                t.create_view(&wgpu::TextureViewDescriptor {
+                    dimension: Some(wgpu::TextureViewDimension::D2Array),
+                    mip_level_count: Some(self.key.2),
+                    ..Default::default()
+                })
+            })
+            .collect();
+        let mut entries = vec![wgpu::BindGroupEntry {
+            binding: 0,
+            resource: self.uniform.as_entire_binding(),
+        }];
+        entries.extend(views.iter().enumerate().map(|(i, v)| wgpu::BindGroupEntry {
+            binding: i as u32 + 1,
+            resource: wgpu::BindingResource::TextureView(v),
+        }));
+        let group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            label: Some("Java shader pack block atlas"),
+            layout: &self.layout,
+            entries: &entries,
+        });
+        for (mip, view) in self.mips.iter().enumerate() {
+            let attachments = [Some(wgpu::RenderPassColorAttachment {
+                view,
+                resolve_target: None,
+                depth_slice: None,
+                ops: wgpu::Operations {
+                    load: wgpu::LoadOp::Clear(wgpu::Color::TRANSPARENT),
+                    store: wgpu::StoreOp::Store,
+                },
+            })];
+            let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+                label: Some("Java shader pack block atlas"),
+                color_attachments: &attachments,
+                ..Default::default()
+            });
+            pass.set_pipeline(&self.pipeline);
+            pass.set_bind_group(0, &group, &[]);
+            pass.draw(0..3, mip as u32..mip as u32 + 1);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// `module` validates and translates for Metal, Vulkan and DirectX 12.
+    fn backends(module: &naga::Module, label: &str) {
+        let info = naga::valid::Validator::new(
+            naga::valid::ValidationFlags::all(),
+            naga::valid::Capabilities::all(),
+        )
+        .validate(module)
+        .unwrap_or_else(|e| panic!("{label}: {e:?}"));
+        naga::back::msl::write_string(
+            module,
+            &info,
+            // wgpu's Metal backend asks for MSL 2.x.
+            &naga::back::msl::Options {
+                lang_version: (2, 4),
+                ..Default::default()
+            },
+            &naga::back::msl::PipelineOptions::default(),
+        )
+        .unwrap_or_else(|e| panic!("{label} (MSL): {e}"));
+        naga::back::spv::write_vec(module, &info, &Default::default(), None)
+            .unwrap_or_else(|e| panic!("{label} (SPIR-V): {e}"));
+        for entry in &module.entry_points {
+            let mut hlsl = String::new();
+            naga::back::hlsl::Writer::new(
+                &mut hlsl,
+                &naga::back::hlsl::Options::default(),
+                &naga::back::hlsl::PipelineOptions {
+                    entry_point: Some((entry.stage, entry.name.clone())),
+                },
+            )
+            .write(module, &info, None)
+            .unwrap_or_else(|e| panic!("{label} {} (HLSL): {e}", entry.name));
+        }
+    }
+
+    /// A terrain program reading every attribute the glue fills, run after
+    /// each draw path's glue, and the atlas shader, on every backend.
+    #[test]
+    fn the_glue_feeds_a_terrain_program_on_every_backend() {
+        let program = "#version 120
+attribute vec4 mc_Entity;
+attribute vec4 mc_midTexCoord;
+attribute vec4 at_tangent;
+attribute vec3 at_midBlock;
+varying vec4 color;
+varying vec2 uv;
+varying vec2 lm;
+varying vec3 normal;
+varying float id;
+void main() {
+    vec4 p = gl_ModelViewMatrix * gl_Vertex;
+    p.xyz += at_midBlock / 64.0 * 0.0 + at_tangent.xyz * 0.0;
+    gl_Position = gl_ProjectionMatrix * p;
+    color = gl_Color;
+    uv = (gl_TextureMatrix[0] * gl_MultiTexCoord0).xy + mc_midTexCoord.xy * 0.0;
+    lm = (gl_TextureMatrix[1] * gl_MultiTexCoord1).xy;
+    normal = gl_NormalMatrix * gl_Normal;
+    id = mc_Entity.x;
+}
+";
+        for flat in [false, true] {
+            let mut link = horizon_shaderpack::translate::Link {
+                set: 2,
+                geometry: Some(glue(flat, Some(0.1))),
+                ..Default::default()
+            };
+            let t = horizon_shaderpack::translate::translate(
+                horizon_shaderpack::Stage::Vertex,
+                program,
+                &mut link,
+                &|l| format!("line {l}"),
+            )
+            .unwrap_or_else(|e| panic!("flat {flat}: {e}"));
+            for wanted in ["hz_vertex();", "mc_Entity = vec4(vec4(hz_block"] {
+                assert!(t.glsl.contains(wanted), "{wanted}\n{}", t.glsl);
+            }
+            // The glue's inputs are Horizon's vertex layout.
+            let inputs = t.module.entry_points[0].function.arguments.len();
+            assert_eq!(inputs, if flat { 6 } else { 7 }, "{}", t.wgsl);
+            let reparsed = naga::front::wgsl::parse_str(&t.wgsl).unwrap();
+            backends(&reparsed, &format!("terrain glue (flat {flat})"));
+        }
+        backends(&naga::front::wgsl::parse_str(ATLAS).unwrap(), "atlas");
+        backends(
+            &naga::front::wgsl::parse_str(super::super::java_stages::BLIT).unwrap(),
+            "Java shader pack blits",
+        );
+    }
+
+    #[test]
+    fn sprites_take_their_blocks_ids() {
+        let layers: BTreeMap<String, u32> = [
+            ("minecraft:block/oak_leaves", 0),
+            ("minecraft:block/water_still", 1),
+            ("minecraft:block/stone", 2),
+            ("minecraft:block/oak_log_top", 3),
+        ]
+        .into_iter()
+        .map(|(n, l)| (n.to_owned(), l))
+        .collect();
+        let ids: BTreeMap<String, i32> = [("oak_leaves", 10003), ("water", 8), ("oak_log", 7)]
+            .into_iter()
+            .map(|(n, i)| (n.to_owned(), i))
+            .collect();
+        assert_eq!(table(&layers, &ids), [2, 0, 10003, 8, -1, 7]);
+        assert_eq!(atlas_columns(5), 3);
+        assert_eq!(atlas_columns(0), 1);
+    }
+}

crates/horizon-client/src/java_pack.rs

@@ -2,13 +2,14 @@
 //! a folder holding `shaders/`, or a `.zip`. `horizon-shaderpack` translates
 //! their full-screen programs (`begin`, `prepare`, `deferred`, `composite`,
 //! `final`) to WGSL, and `gfx/java_stages.rs` runs them over Horizon's world
-//! as Iris runs them over its own. Geometry programs (`gbuffers_*`,
-//! `shadow`) don't run yet: the world is drawn by Horizon.
+//! as Iris runs them over its own. Of the geometry programs, the terrain's
+//! (`gbuffers_terrain`, `gbuffers_water` and their fallbacks) draw Horizon's
+//! terrain (`gfx/java_terrain.rs`); the rest of the world is Horizon's.
 use horizon_shaderpack::{
     JavaPack,
-    pipeline::{Directives, Program, TargetSettings},
+    pipeline::{Directives, GeometryProgram, Pass, Program, TargetSettings},
     preprocess::Environment,
-    properties::SkyDirectives,
+    properties::{Blend, SkyDirectives},
     uniforms::CustomUniforms,
 };
 use std::{
@@ -36,6 +37,17 @@ pub struct JavaFolder {
     /// `sunPathRotation`, `eyeBrightnessHalflife`, `wetnessHalflife` and
     /// `drynessHalflife`.
     pub directives: Directives,
+    /// The programs Horizon's solid and translucent terrain are drawn with,
+    /// each translated for instanced and flat draws (`variants[0]`).
+    pub terrain: Option<GeometryProgram>,
+    pub water: Option<GeometryProgram>,
+    /// How many of `passes` run before translucent terrain (`begin*`,
+    /// `prepare*`, `deferred*`).
+    pub translucent_at: usize,
+    pub flipped_after_translucent: BTreeSet<u32>,
+    /// Each draw buffer's blending in `terrain` and `water`.
+    pub terrain_blends: Vec<Option<wgpu::BlendState>>,
+    pub water_blends: Vec<Option<wgpu::BlendState>>,
 }
 
 /// The key of `texture.noise` (`noisetex`) in [`JavaPasses::custom_textures`].
@@ -60,6 +72,8 @@ pub struct JavaPasses {
     pub uniforms: CustomUniforms,
     /// What the pack keeps of the vanilla sky (`clouds`, `sun`, `moon`).
     pub sky: SkyDirectives,
+    /// `block.properties`: block name → `mc_Entity` id.
+    pub block_ids: BTreeMap<String, i32>,
     /// `texture.<stage>.<sampler>` and `texture.noise` images, by
     /// `"<stage>.<sampler>"` and [`NOISE_KEY`].
     pub custom_textures: BTreeMap<String, crate::shader_pack::Rgba>,
@@ -144,6 +158,45 @@ pub fn load(
         if passes.is_empty() && final_pass.is_none() {
             continue;
         }
+        // A geometry program that doesn't translate leaves that terrain to
+        // Horizon, with a warning.
+        let geometry = |pass: &Option<horizon_shaderpack::pipeline::Pass>, alpha_test| {
+            let pass = pass.as_ref()?;
+            let glues = [false, true].map(|flat| crate::gfx::java_terrain::glue(flat, alpha_test));
+            match pack.compile_geometry(pass, &plan.targets, &values, &env, &properties, &glues) {
+                Ok(program) => Some(program),
+                Err(e) => {
+                    log::warn!("Horizon: shader pack {}: {e}", pass.program);
+                    None
+                }
+            }
+        };
+        // Iris's alpha test of cutout terrain (`AlphaTests.ONE_TENTH_ALPHA`).
+        let terrain = geometry(&plan.terrain, Some(0.1));
+        let water = terrain.as_ref().and_then(|_| geometry(&plan.water, None));
+        let translucent_at = early.clone().count() + plan.deferred.len();
+        let blends = |g: &Option<GeometryProgram>, default| {
+            g.as_ref().map_or_else(Vec::new, |g| {
+                pass_blends(&g.program.pass, &g.program.draw_buffers, default)
+            })
+        };
+        let terrain_blends = blends(&terrain, None);
+        // Vanilla's translucent blending (`BlendFunction.TRANSLUCENT`).
+        let water_blends = blends(
+            &water,
+            Some(wgpu::BlendState {
+                color: wgpu::BlendComponent {
+                    src_factor: wgpu::BlendFactor::SrcAlpha,
+                    dst_factor: wgpu::BlendFactor::OneMinusSrcAlpha,
+                    operation: wgpu::BlendOperation::Add,
+                },
+                alpha: wgpu::BlendComponent {
+                    src_factor: wgpu::BlendFactor::One,
+                    dst_factor: wgpu::BlendFactor::OneMinusSrcAlpha,
+                    operation: wgpu::BlendOperation::Add,
+                },
+            }),
+        );
         folders.push(JavaFolder {
             folder: name.to_owned(),
             targets: plan.targets,
@@ -154,6 +207,12 @@ pub fn load(
             final_pass,
             flipped_at_end: plan.flipped_at_end,
             directives: plan.directives,
+            terrain,
+            water,
+            translucent_at,
+            flipped_after_translucent: plan.flipped_after_translucent,
+            terrain_blends,
+            water_blends,
         });
     }
     if folders.is_empty() {
@@ -184,11 +243,69 @@ pub fn load(
     for problem in &uniforms.problems {
         log::warn!("Horizon: shader pack custom uniform {problem}");
     }
+    let block_ids = pack.block_ids(&values, &env).unwrap_or_else(|e| {
+        log::warn!("Horizon: shader pack {e}");
+        BTreeMap::new()
+    });
     Ok(JavaPasses {
         folders,
         uniforms,
         sky: properties.sky(),
         custom_textures,
+        block_ids,
+    })
+}
+
+/// Each draw buffer's blending, as Iris's `BlendModeOverride`:
+/// `blend.<program>.<buffer>`, else `blend.<program>`, else `default`
+/// (none for full-screen passes, vanilla's for the geometry programs).
+pub(crate) fn pass_blends(
+    pass: &Pass,
+    draw_buffers: &[u32],
+    default: Option<wgpu::BlendState>,
+) -> Vec<Option<wgpu::BlendState>> {
+    let all = pass.blend.as_ref().map_or(default, blend_state);
+    draw_buffers
+        .iter()
+        .map(|i| {
+            pass.buffer_blends
+                .iter()
+                .find(|(b, _)| b == i)
+                .map_or(all, |(_, b)| blend_state(b))
+        })
+        .collect()
+}
+
+/// A `blend.*` value as wgpu's blending (`off`: none). The factors are the
+/// GL ones `ShaderProperties` accepts.
+pub(crate) fn blend_state(blend: &Blend) -> Option<wgpu::BlendState> {
+    let Blend::Factors(factors) = blend else {
+        return None;
+    };
+    let factor = |name: &str| {
+        use wgpu::BlendFactor as F;
+        match name {
+            "ZERO" => F::Zero,
+            "SRC_COLOR" => F::Src,
+            "ONE_MINUS_SRC_COLOR" => F::OneMinusSrc,
+            "DST_COLOR" => F::Dst,
+            "ONE_MINUS_DST_COLOR" => F::OneMinusDst,
+            "SRC_ALPHA" => F::SrcAlpha,
+            "ONE_MINUS_SRC_ALPHA" => F::OneMinusSrcAlpha,
+            "DST_ALPHA" => F::DstAlpha,
+            "ONE_MINUS_DST_ALPHA" => F::OneMinusDstAlpha,
+            "SRC_ALPHA_SATURATE" => F::SrcAlphaSaturated,
+            _ => F::One,
+        }
+    };
+    let component = |src: &str, dst: &str| wgpu::BlendComponent {
+        src_factor: factor(src),
+        dst_factor: factor(dst),
+        operation: wgpu::BlendOperation::Add,
+    };
+    Some(wgpu::BlendState {
+        color: component(&factors[0], &factors[1]),
+        alpha: component(&factors[2], &factors[3]),
     })
 }
 
@@ -242,8 +359,18 @@ mod tests {
             .folders
             .iter()
             .flat_map(|f| f.passes.iter().chain(&f.final_pass));
+        let geometry = pack
+            .folders
+            .iter()
+            .flat_map(|f| f.terrain.iter().chain(&f.water));
         passes
             .flat_map(|p| [(p, &p.vertex, "vsh"), (p, &p.fragment, "fsh")])
+            .chain(geometry.flat_map(|g| {
+                let p = &g.program;
+                [(p, &p.vertex, "vsh"), (p, &p.fragment, "fsh")]
+                    .into_iter()
+                    .chain(g.variants.iter().map(move |v| (p, v, "vsh (flat)")))
+            }))
             .find_map(|(p, t, ext)| {
                 let e = naga::front::wgsl::parse_str(&t.wgsl).err()?;
                 Some(format!(
@@ -283,7 +410,13 @@ mod tests {
                         .iter()
                         .map(|f| {
                             let n = f.passes.len() + usize::from(f.final_pass.is_some());
-                            format!("{} {n} passes", f.folder)
+                            let geometry: Vec<&str> = f
+                                .terrain
+                                .iter()
+                                .chain(&f.water)
+                                .map(|g| g.program.pass.program.as_str())
+                                .collect();
+                            format!("{} {n} passes, terrain {geometry:?}", f.folder)
                         })
                         .collect();
                     println!("{name}: loads ({})", folders.join(", "));

crates/horizon-client/src/lan/guest.rs

@@ -432,6 +432,13 @@ pub fn stack_to_network(
     item_id: impl Fn(&str) -> i32,
     enchantment_id: impl Fn(&str) -> Option<i32>,
     s: &Option<ItemStack>,
+) -> Option<Stack> {
+    network_stack(&item_id, &enchantment_id, s)
+}
+fn network_stack(
+    item_id: &dyn Fn(&str) -> i32,
+    enchantment_id: &dyn Fn(&str) -> Option<i32>,
+    s: &Option<ItemStack>,
 ) -> Option<Stack> {
     let s = s.as_ref()?;
     let mut stack = Stack::new(item_id(&s.item), s.count as i32);
@@ -488,6 +495,18 @@ pub fn stack_to_network(
                 horizon_protocol::item::Component::Int(i32::from(mode)),
             ));
         }
+        // A loaded crossbow's ammunition.
+        if !d.charged.is_empty() {
+            let charged = d
+                .charged
+                .iter()
+                .filter_map(|c| network_stack(item_id, enchantment_id, &Some(c.clone())))
+                .collect();
+            stack.added.push((
+                horizon_protocol::item::component::CHARGED_PROJECTILES,
+                horizon_protocol::item::Component::Stacks(charged),
+            ));
+        }
         // The books a lectern shows and a guest reads.
         if !d.writable_pages.is_empty() {
             stack.added.push((

crates/horizon-client/src/lan/hub.rs

@@ -1981,14 +1981,15 @@ impl Hub {
                     self.guests[i].sneaking = p.flags & 32 != 0;
                     self.guests[i].sprinting = p.flags & 64 != 0 && p.flags & 1 != 0;
                 }
-                // OPEN_INVENTORY is the game's: the ridden mount's inventory.
-                S::PlayerCommand(p) if p.action == 5 => {
+                // OPEN_INVENTORY (the ridden mount's inventory) and
+                // START_FALL_FLYING (checked against the guest's chest slot
+                // and effects) are the game's.
+                S::PlayerCommand(p) if matches!(p.action, 5 | 6) => {
                     events.push(HostEvent::Packet(conn, Box::new(S::PlayerCommand(p))));
                 }
                 S::PlayerCommand(p) => match p.action {
                     1 => self.guests[i].sprinting = true,
                     2 => self.guests[i].sprinting = false,
-                    6 => self.guests[i].fall_flying = true,
                     // STOP_SLEEPING.
                     0 => self.wake(i),
                     _ => {}

crates/horizon-client/src/mobs.rs

@@ -2277,7 +2277,7 @@ mod sensor_scan_tests {
     use horizon_core::geometry::Vec3;
     use serde_json::json;
 
-    fn kind() -> Arc<MobType> {
+    pub(super) fn kind() -> Arc<MobType> {
         Arc::new(MobType {
             id: "minecraft:cow".into(),
             species: Species::Cow,
@@ -2481,56 +2481,9 @@ mod sensor_scan_tests {
 }
 #[cfg(test)]
 mod push_tests {
+    use super::sensor_scan_tests::kind;
     use super::*;
     use horizon_core::geometry::Vec3;
-    use serde_json::json;
-
-    fn kind() -> Arc<MobType> {
-        Arc::new(MobType {
-            id: "minecraft:cow".into(),
-            species: Species::Cow,
-            width: 0.9,
-            height: 1.4,
-            eye_height: 1.3,
-            category: "creature".into(),
-            max_health: 10.0,
-            speed: 0.2,
-            flying_speed: 0.4,
-            attack_damage: 0.0,
-            attack_knockback: 0.0,
-            follow_range: 16.0,
-            step_height: 0.6,
-            armor: 0.0,
-            armor_toughness: 0.0,
-            knockback_resistance: 0.0,
-            jump_strength: 0.42,
-            attributes: Arc::default(),
-            gravity: 0.08,
-            safe_fall_distance: 3.0,
-            fall_damage_multiplier: 1.0,
-            water_efficiency: 0.0,
-            water_slowdown: 0.8,
-            air_speed: 0.02,
-            baby_scale: 0.5,
-            head_rot_speed: 10.0,
-            max_head_x_rot: 40.0,
-            max_head_y_rot: 75.0,
-            ambient_interval: 120,
-            flags: Flags {
-                animal: true,
-                ..Default::default()
-            },
-            model: Arc::new(Part::parse("root", &json!({}))),
-            layers: HashMap::new(),
-            texture: String::new(),
-            brain: Brain::Passive,
-            anim: Anim::Rabbit,
-            sounds: [""; 3],
-            step_sound: None,
-            food: Arc::default(),
-            tempt: Arc::default(),
-        })
-    }
 
     /// The pending pushes as one list, scanned for each mob, as before.
     fn take_old(events: &mut Vec<MobEvent>, from: usize, pending: &mut Vec<(u32, Vec3)>) {

crates/horizon-client/src/mobs/animal_brain.rs

@@ -9,7 +9,12 @@
 //! own random drives positions, sounds and jumps. `RunOne` shuffles with a
 //! random of its own, seeded with the brain's `shuffle_seed` when it is
 //! built.
-use super::{Mob, MobEvent, MobWorld, Species, Who, path::Path, sniffer};
+use super::{
+    Mob, MobEvent, MobWorld, Species, Who,
+    brain::{Timed, living_near},
+    path::Path,
+    sniffer,
+};
 use horizon_core::{
     geometry::Vec3,
     random::{LegacyRandom, RandomSource},
@@ -603,22 +608,7 @@ fn tick_sensors(m: &mut Mob, w: &MobWorld) {
 /// `NearestLivingEntitySensor`: everything alive within the follow range,
 /// nearest first.
 fn sense_living(m: &mut Mob, w: &MobWorld) {
-    let r = m.attrs.follow_range;
-    let area = m.bounds().inflate(Vec3::new(r, r, r));
-    let mut found: Vec<(Who, f64)> = Vec::new();
-    for o in w.others_near(area) {
-        if o.id != m.id && o.alive && o.bounds.intersects(area) {
-            found.push((Who::Mob(o.id), m.distance_sqr(o.position)));
-        }
-    }
-    if let Some(p) = &w.player
-        && p.alive
-        && p.bounds.intersects(area)
-    {
-        found.push((Who::Player, m.distance_sqr(p.position)));
-    }
-    found.sort_by(|a, b| a.1.total_cmp(&b.1));
-    let list: Vec<Who> = found.into_iter().map(|(w, _)| w).collect();
+    let list = living_near(m, w);
     let mm = mem(m);
     mm.mobs.set_list(list.clone());
     mm.visible_mobs.set(Visible {
@@ -794,37 +784,6 @@ fn followable_friendly(s: Species) -> bool {
 
 // ---- Behaviours ------------------------------------------------------------
 
-/// `Behavior`'s running state and end time.
-#[derive(Clone, Copy, Debug)]
-struct Timed {
-    running: bool,
-    end: i64,
-    min: i32,
-    max: i32,
-}
-impl Timed {
-    fn new(min: i32, max: i32) -> Self {
-        Self {
-            running: false,
-            end: 0,
-            min,
-            max,
-        }
-    }
-    /// `Behavior.tryStart`'s duration draw.
-    fn begin(&mut self, cx: &mut Bx) {
-        self.running = true;
-        let bound = self.max.wrapping_add(1).wrapping_sub(self.min);
-        let d = self
-            .min
-            .wrapping_add(cx.lr.next_int_bound(bound).unwrap_or(0));
-        self.end = cx.now + i64::from(d);
-    }
-    fn timed_out(&self, now: i64) -> bool {
-        now > self.end
-    }
-}
-
 /// `RunOne`: shuffles its children by weight and starts the first that can.
 #[derive(Clone, Debug)]
 struct Gate {
@@ -1076,7 +1035,7 @@ impl B {
                 {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 mem(m).walk_target.clear();
                 mem(m).look_target.clear();
                 m.add_effect("minecraft:regeneration", 200, 0);
@@ -1086,7 +1045,7 @@ impl B {
                 if !swim_condition(m) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::AnimalPanic { t, .. } => {
@@ -1094,7 +1053,7 @@ impl B {
                 if !(mm.hurt_by.get() == Some(&true) || mm.is_panicking.present()) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 if brain_mut(m).kind == Kind::Sniffer {
                     reset_sniffing(m, cx);
                 }
@@ -1123,7 +1082,7 @@ impl B {
                 let reached = reached(m, cx.w, &walk);
                 if !reached && compute_path(m, cx, &walk, path, speed) {
                     *last_target = walk.target.block(cx.w);
-                    t.begin(cx);
+                    t.begin(cx.lr, cx.now);
                     mem(m).path.set_opt(path.clone());
                     m.nav_move_to_path(path.clone(), f64::from(*speed));
                     return true;
@@ -1139,21 +1098,21 @@ impl B {
                 if !mem(m).temptation_cooldown_ticks.present() {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::CountDownGaze(t) => {
                 if !mem(m).gaze_cooldown_ticks.present() {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::CountDownTransport(t) => {
                 if !mem(m).transport_items_cooldown_ticks.present() {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::Transport(x) => x.try_start(m, cx),
@@ -1171,7 +1130,7 @@ impl B {
                 let Some(partner) = breed_partner(m, cx.w) else {
                     return false;
                 };
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 if brain_mut(m).kind == Kind::Sniffer {
                     reset_sniffing(m, cx);
                 }
@@ -1200,7 +1159,7 @@ impl B {
                 {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 if brain_mut(m).kind == Kind::Sniffer {
                     reset_sniffing(m, cx);
                 }
@@ -1210,14 +1169,14 @@ impl B {
                 if !mem(m).look_target.present() {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::FeelingHappy(t) => {
                 if !mem(m).sniffer_happy.present() {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 transition(m, cx, sniffer::FEELING_HAPPY);
                 true
             }
@@ -1233,7 +1192,7 @@ impl B {
                 if !can_sniff(m) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 transition(m, cx, sniffer::DIGGING);
                 true
             }
@@ -1246,7 +1205,7 @@ impl B {
                 {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 transition(m, cx, sniffer::RISING);
                 true
             }
@@ -1261,7 +1220,7 @@ impl B {
                 if !can_sniff(m) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 transition(m, cx, sniffer::SEARCHING);
                 true
             }
@@ -1278,7 +1237,7 @@ impl B {
                 if is_tempted(m) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 transition(m, cx, sniffer::SCENTING);
                 true
             }
@@ -1293,12 +1252,12 @@ impl B {
                 if m.is_baby() || !can_sniff(m) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 transition(m, cx, sniffer::SNIFFING);
                 true
             }
             B::DoNothing(t) => {
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::AxolotlAction { .. }

crates/horizon-client/src/mobs/brain.rs

@@ -1,8 +1,11 @@
 //! Pieces of vanilla's `Brain` that species implemented as brains share:
 //! memories that expire, behaviour durations, walk targets and
 //! `MoveToTargetSink`.
-use super::{Mob, goals::Cx};
-use horizon_core::random::RandomSource;
+use super::{Mob, MobWorld, Who, goals::Cx};
+use horizon_core::{
+    geometry::Vec3,
+    random::{LegacyRandom, RandomSource},
+};
 
 /// A memory with an expiry (`Brain.setMemoryWithExpiry`): present for the
 /// tick it was set and `ttl` more ticks. `Ttl::default()` is absent.
@@ -25,6 +28,57 @@ impl Ttl {
         }
     }
 }
+/// `Behavior`'s bookkeeping in the brains ported behaviour for behaviour
+/// (villager, animal, monster, warden): running, and until when.
+#[derive(Clone, Copy, Debug)]
+pub struct Timed {
+    pub running: bool,
+    pub end: i64,
+    pub min: i32,
+    pub max: i32,
+}
+impl Timed {
+    pub fn new(min: i32, max: i32) -> Self {
+        Self {
+            running: false,
+            end: 0,
+            min,
+            max,
+        }
+    }
+    /// `Behavior.tryStart`'s duration draw from the level random, in Java's
+    /// int arithmetic (made even when it cannot vary).
+    pub fn begin(&mut self, lr: &mut LegacyRandom, now: i64) {
+        self.running = true;
+        let bound = self.max.wrapping_add(1).wrapping_sub(self.min);
+        let d = self.min.wrapping_add(lr.next_int_bound(bound).unwrap_or(0));
+        self.end = now + i64::from(d);
+    }
+    /// `Behavior.timedOut`.
+    pub fn timed_out(&self, now: i64) -> bool {
+        now > self.end
+    }
+}
+/// `NearestLivingEntitySensor`'s scan: the living entities (the player
+/// among them) whose boxes meet the follow range around `m`, nearest first.
+pub fn living_near(m: &Mob, w: &MobWorld) -> Vec<Who> {
+    let r = m.attrs.follow_range;
+    let area = m.bounds().inflate(Vec3::new(r, r, r));
+    let mut found: Vec<(Who, f64)> = Vec::new();
+    for o in w.others_near(area) {
+        if o.id != m.id && o.alive && o.bounds.intersects(area) {
+            found.push((Who::Mob(o.id), m.distance_sqr(o.position)));
+        }
+    }
+    if let Some(p) = &w.player
+        && p.alive
+        && p.bounds.intersects(area)
+    {
+        found.push((Who::Player, m.distance_sqr(p.position)));
+    }
+    found.sort_by(|a, b| a.1.total_cmp(&b.1));
+    found.into_iter().map(|(w, _)| w).collect()
+}
 /// A random duration in `min..=max` (`Behavior`'s end time).
 pub fn duration(m: &mut Mob, min: i32, max: i32) -> i32 {
     if max <= min {

crates/horizon-client/src/mobs/monster_brain.rs

@@ -11,9 +11,10 @@
 //! seeded when the brain is built.
 use super::{
     Mob, MobEvent, MobWorld, Species, Who,
+    brain::{Timed, living_near},
     goals::Cx,
     path::Path,
-    villager_brain::{NEVER, Slot, Tracker, Visible, WalkTarget},
+    villager_brain::{NEVER, Slot, Tracker, Visible, WalkTarget, compute_path, reached},
 };
 use crate::projectiles::{Projectile, ProjectileKind};
 use horizon_core::{
@@ -129,6 +130,10 @@ fn brain_mut(m: &mut Mob) -> &mut Brain {
 fn mem(m: &mut Mob) -> &mut Memories {
     &mut brain_mut(m).mem
 }
+/// `CANT_REACH_WALK_TARGET_SINCE`, for `compute_path`.
+fn cant_reach(m: &mut Mob) -> &mut Slot<i64> {
+    &mut mem(m).cant_reach_walk_target_since
+}
 fn mem_ref(m: &Mob) -> &Memories {
     &brain(m).expect("brain").mem
 }
@@ -292,22 +297,7 @@ fn tick_sensors(m: &mut Mob, w: &MobWorld) {
 /// `NearestLivingEntitySensor`: everything alive within the follow range,
 /// nearest first.
 fn sense_living(m: &mut Mob, w: &MobWorld) {
-    let r = m.attrs.follow_range;
-    let area = m.bounds().inflate(Vec3::new(r, r, r));
-    let mut found: Vec<(Who, f64)> = Vec::new();
-    for o in w.others_near(area) {
-        if o.id != m.id && o.alive && o.bounds.intersects(area) {
-            found.push((Who::Mob(o.id), m.distance_sqr(o.position)));
-        }
-    }
-    if let Some(p) = &w.player
-        && p.alive
-        && p.bounds.intersects(area)
-    {
-        found.push((Who::Player, m.distance_sqr(p.position)));
-    }
-    found.sort_by(|a, b| a.1.total_cmp(&b.1));
-    let list: Vec<Who> = found.into_iter().map(|(w, _)| w).collect();
+    let list = living_near(m, w);
     let mm = mem(m);
     mm.mobs.set_list(list.clone());
     mm.visible_mobs.set(Visible {
@@ -456,31 +446,6 @@ fn sense_breeze_attack(m: &mut Mob, w: &MobWorld) {
 
 // ---- Behaviours ---------------------------------------------------------
 
-/// `Behavior`'s bookkeeping: running, and until when.
-#[derive(Clone, Debug)]
-struct Timed {
-    running: bool,
-    end: i64,
-    min: i32,
-    max: i32,
-}
-impl Timed {
-    fn new(min: i32, max: i32) -> Self {
-        Self {
-            running: false,
-            end: 0,
-            min,
-            max,
-        }
-    }
-    /// `Behavior.tryStart`'s duration draw from the level random.
-    fn begin(&mut self, cx: &mut Bx) {
-        self.running = true;
-        let d = self.min + cx.lr.next_int_bound(self.max + 1 - self.min).unwrap_or(0);
-        self.end = cx.now + i64::from(d);
-    }
-}
-
 /// `StartAttacking`'s target finders.
 #[derive(Clone, Copy, Debug)]
 enum Finder {
@@ -607,14 +572,14 @@ impl B {
                 if *creaking && !super::creaking::can_move(m) || !swim_condition(m) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::LookAtTargetSink(t) => {
                 if !mem(m).look_target.present() {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::MoveToTargetSink {
@@ -636,9 +601,9 @@ impl B {
                 }
                 let walk = mm.walk_target.value().unwrap();
                 let reached = reached(m, cx.w, &walk);
-                if !reached && compute_path(m, cx, &walk, path, speed) {
+                if !reached && compute_path(m, cx.w, cx.now, &walk, path, speed, cant_reach) {
                     *last_target = walk.target.block(cx.w);
-                    t.begin(cx);
+                    t.begin(cx.lr, cx.now);
                     // start
                     mem(m).path.set_opt(path.clone());
                     m.nav_move_to_path(path.clone(), f64::from(*speed));
@@ -719,7 +684,7 @@ impl B {
                 true
             }
             B::DoNothing(t) => {
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::RandomStroll(running, speed) => {
@@ -848,7 +813,7 @@ impl B {
                     mem(m).breeze_shoot.clear();
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 // start
                 super::breeze::set_pose(m, super::breeze::SHOOTING);
                 mem(m).breeze_shoot_charging.set_ttl((), 15);
@@ -867,7 +832,7 @@ impl B {
                 if !long_jump_can_run(m, cx) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 // start
                 if !mem(m).breeze_jump_inhaling.present() {
                     mem(m).breeze_jump_inhaling.set_ttl((), 10);
@@ -905,7 +870,7 @@ impl B {
                 if !stuck {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 mem(m).breeze_shoot.set_ttl((), 60);
                 true
             }
@@ -924,7 +889,7 @@ impl B {
                 {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 slide_start(m, cx);
                 true
             }
@@ -989,7 +954,7 @@ impl B {
                     && let Some(now_target) = walk.target.block(cx.w)
                 {
                     let d = manhattan_sq(now_target, last);
-                    if d > 4 && compute_path(m, cx, &walk, path, speed) {
+                    if d > 4 && compute_path(m, cx.w, cx.now, &walk, path, speed, cant_reach) {
                         *last_target = Some(now_target);
                         mem(m).path.set_opt(path.clone());
                         m.nav_move_to_path(path.clone(), f64::from(*speed));
@@ -1122,53 +1087,6 @@ fn tracker_visible(m: &mut Mob, w: &MobWorld, t: Tracker) -> bool {
         _ => true,
     }
 }
-/// `MoveToTargetSink.reachedTarget`.
-fn reached(m: &Mob, w: &MobWorld, walk: &WalkTarget) -> bool {
-    walk.target.block(w).is_some_and(|p| {
-        let h = block_of(m.position);
-        (p[0] - h[0]).abs() + (p[1] - h[1]).abs() + (p[2] - h[2]).abs() <= walk.close
-    })
-}
-/// `MoveToTargetSink.tryComputePath`.
-fn compute_path(
-    m: &mut Mob,
-    cx: &mut Bx,
-    walk: &WalkTarget,
-    path: &mut Option<Path>,
-    speed: &mut f32,
-) -> bool {
-    let Some(target) = walk.target.block(cx.w) else {
-        return false;
-    };
-    *path = m.create_path_to(cx.w, target, 0);
-    *speed = walk.speed;
-    if reached(m, cx.w, walk) {
-        mem(m).cant_reach_walk_target_since.clear();
-    } else {
-        let can_reach = path.as_ref().is_some_and(|p| p.reached);
-        let mm = mem(m);
-        if can_reach {
-            mm.cant_reach_walk_target_since.clear();
-        } else if !mm.cant_reach_walk_target_since.present() {
-            mm.cant_reach_walk_target_since.set(cx.now);
-        }
-        if path.is_some() {
-            return true;
-        }
-        let to = [
-            f64::from(target[0]) + 0.5,
-            f64::from(target[1]),
-            f64::from(target[2]) + 0.5,
-        ];
-        if let Some(step) =
-            m.default_random_pos_towards(cx.w, 10, 7, to, f64::from(std::f32::consts::FRAC_PI_2))
-        {
-            *path = m.create_path_to(cx.w, block_of(Vec3::new(step[0], step[1], step[2])), 0);
-            return path.is_some();
-        }
-    }
-    false
-}
 /// `BehaviorUtils.isWithinAttackRange(body, target, 1)` for a mob without a
 /// ranged weapon: `Mob.isWithinMeleeAttackRange`.
 fn within_attack_range(m: &Mob, w: &MobWorld, target: Who) -> bool {

crates/horizon-client/src/mobs/villager_brain.rs

@@ -11,6 +11,7 @@
 //! `Brain::shuffle_seed` when the brain is built.
 use super::{
     Mob, MobEvent, MobWorld, Species, Who,
+    brain::{Timed, living_near},
     path::{Path, PathNode},
 };
 use horizon_core::{
@@ -341,6 +342,10 @@ fn brain_mut(m: &mut Mob) -> &mut Brain {
 fn mem(m: &mut Mob) -> &mut Memories {
     &mut brain_mut(m).mem
 }
+/// `CANT_REACH_WALK_TARGET_SINCE`, for `compute_path`.
+fn cant_reach(m: &mut Mob) -> &mut Slot<i64> {
+    &mut mem(m).cant_reach_walk_target_since
+}
 fn mem_ref(m: &Mob) -> Option<&Memories> {
     brain(m).map(|b| &b.mem)
 }
@@ -565,22 +570,7 @@ const FOLLOW_RANGE: f64 = 16.0;
 /// `NearestLivingEntitySensor`: everything alive within the follow range,
 /// nearest first.
 fn sense_living(m: &mut Mob, w: &MobWorld) {
-    let r = m.attrs.follow_range;
-    let area = m.bounds().inflate(Vec3::new(r, r, r));
-    let mut found: Vec<(Who, f64)> = Vec::new();
-    for o in w.others_near(area) {
-        if o.id != m.id && o.alive && o.bounds.intersects(area) {
-            found.push((Who::Mob(o.id), m.distance_sqr(o.position)));
-        }
-    }
-    if let Some(p) = &w.player
-        && p.alive
-        && p.bounds.intersects(area)
-    {
-        found.push((Who::Player, m.distance_sqr(p.position)));
-    }
-    found.sort_by(|a, b| a.1.total_cmp(&b.1));
-    let list: Vec<Who> = found.into_iter().map(|(w, _)| w).collect();
+    let list = living_near(m, w);
     let mm = mem(m);
     mm.mobs.set_list(list.clone());
     mm.visible_mobs.set(Visible {
@@ -791,34 +781,6 @@ fn sense_golem(m: &mut Mob, w: &MobWorld) {
 
 // ---- Behaviours ---------------------------------------------------------
 
-/// `Behavior`'s bookkeeping: running, and until when.
-#[derive(Clone, Debug)]
-struct Timed {
-    running: bool,
-    end: i64,
-    min: i32,
-    max: i32,
-}
-impl Timed {
-    fn new(min: i32, max: i32) -> Self {
-        Self {
-            running: false,
-            end: 0,
-            min,
-            max,
-        }
-    }
-    /// `Behavior.tryStart`'s duration draw.
-    fn begin(&mut self, cx: &mut Bx) {
-        self.running = true;
-        let bound = self.max.wrapping_add(1).wrapping_sub(self.min);
-        let d = self
-            .min
-            .wrapping_add(cx.lr.next_int_bound(bound).unwrap_or(0));
-        self.end = cx.now + i64::from(d);
-    }
-}
-
 /// The POI types villagers use.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum Poi {
@@ -1498,18 +1460,18 @@ impl B {
                 if !swim_condition(m) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::LookAtTargetSink(t) => {
                 if !mem(m).look_target.present() {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::PanicTrigger(t) => {
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 // VillagerPanicTrigger.start
                 if panic_condition(m) {
                     if !brain_mut(m).is_active(Act::Panic) {
@@ -1542,9 +1504,9 @@ impl B {
                 }
                 let walk = mm.walk_target.value().unwrap();
                 let reached = reached(m, cx.w, &walk);
-                if !reached && compute_path(m, cx, &walk, path, speed) {
+                if !reached && compute_path(m, cx.w, cx.now, &walk, path, speed, cant_reach) {
                     *last_target = walk.target.block(cx.w);
-                    t.begin(cx);
+                    t.begin(cx.lr, cx.now);
                     // start
                     mem(m).path.set_opt(path.clone());
                     m.nav_move_to_path(path.clone(), f64::from(*speed));
@@ -1561,7 +1523,7 @@ impl B {
                 if !follow_trading_condition(m, cx.w) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 follow_trading_player(m);
                 true
             }
@@ -1573,7 +1535,7 @@ impl B {
                 if !matches!(a, Act::Idle | Act::Work | Act::Play) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::JumpOnBed {
@@ -1590,7 +1552,7 @@ impl B {
                 if mm.walk_target.present() || !m.is_baby() {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 *bed = Some(nearest);
                 *time_left = 100;
                 *jumps = 3 + cx.lr.next_int_bound(4).unwrap_or(0);
@@ -1599,7 +1561,7 @@ impl B {
                 true
             }
             B::DoNothing(t) => {
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::GiveGiftToHero {
@@ -1618,7 +1580,7 @@ impl B {
                     *until_next -= 1;
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 *given = false;
                 *started = now;
                 let mm = mem(m);
@@ -1630,7 +1592,7 @@ impl B {
                 if !mem(m).interaction_target.present() || !show_trades_condition(m, cx.w) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 // start
                 if let Some(target) = mem(m).interaction_target.value() {
                     mem(m).look_target.set(Tracker::Entity(target, true));
@@ -1646,7 +1608,7 @@ impl B {
                 if !villager_target_valid(m, cx.w, Mem::InteractionTarget) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 let target = mem(m).interaction_target.value().unwrap();
                 lock_gaze(m, target, cx);
                 true
@@ -1659,7 +1621,7 @@ impl B {
                 if !breeding_possible(m, cx.w) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 let target = mem(m).breed_target.value().unwrap();
                 lock_gaze(m, target, cx);
                 *birth = now + 275 + i64::from(m.random.next_int_bound(50).unwrap_or(0));
@@ -1680,7 +1642,7 @@ impl B {
                 if !closer_to_center(site, m.position, 1.73) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 // start
                 let mm = mem(m);
                 mm.last_worked_at_poi.set(now);
@@ -1709,7 +1671,7 @@ impl B {
                 *valid = farmland_around(m, cx.w);
                 *target = pick_farmland(valid, cx);
                 let Some(p) = *target else { return false };
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 if now > *next_ok {
                     let mm = mem(m);
                     mm.look_target.set(Tracker::Block(p));
@@ -2288,7 +2250,7 @@ impl B {
                 {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 if now > *next_ok {
                     if super::villager::start_sleeping(m, home, w) {
                         mem(m).last_slept.set(now);
@@ -2609,7 +2571,7 @@ impl B {
                 {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::LocateHidingPlace {
@@ -2769,7 +2731,7 @@ impl B {
                     && let Some(now_target) = walk.target.block(cx.w)
                 {
                     let d = manhattan_sq(now_target, last);
-                    if d > 4 && compute_path(m, cx, &walk, path, speed) {
+                    if d > 4 && compute_path(m, cx.w, cx.now, &walk, path, speed, cant_reach) {
                         *last_target = Some(now_target);
                         mem(m).path.set_opt(path.clone());
                         m.nav_move_to_path(path.clone(), f64::from(*speed));
@@ -3141,33 +3103,37 @@ fn tracker_visible(m: &mut Mob, w: &MobWorld, t: Tracker) -> bool {
     }
 }
 /// `MoveToTargetSink.reachedTarget`.
-fn reached(m: &Mob, w: &MobWorld, walk: &WalkTarget) -> bool {
+pub(super) fn reached(m: &Mob, w: &MobWorld, walk: &WalkTarget) -> bool {
     walk.target
         .block(w)
         .is_some_and(|p| manhattan(p, block_of(m.position)) <= walk.close)
 }
-/// `MoveToTargetSink.tryComputePath`.
-fn compute_path(
+/// `MoveToTargetSink.tryComputePath`, for the brains on these memories
+/// (villager, monster, warden): `cant_reach` is the brain's
+/// `CANT_REACH_WALK_TARGET_SINCE`.
+pub(super) fn compute_path(
     m: &mut Mob,
-    cx: &mut Bx,
+    w: &MobWorld,
+    now: i64,
     walk: &WalkTarget,
     path: &mut Option<Path>,
     speed: &mut f32,
+    cant_reach: fn(&mut Mob) -> &mut Slot<i64>,
 ) -> bool {
-    let Some(target) = walk.target.block(cx.w) else {
+    let Some(target) = walk.target.block(w) else {
         return false;
     };
-    *path = m.create_path_to(cx.w, target, 0);
+    *path = m.create_path_to(w, target, 0);
     *speed = walk.speed;
-    if reached(m, cx.w, walk) {
-        mem(m).cant_reach_walk_target_since.clear();
+    if reached(m, w, walk) {
+        cant_reach(m).clear();
     } else {
         let can_reach = path.as_ref().is_some_and(|p| p.reached);
-        let mm = mem(m);
+        let since = cant_reach(m);
         if can_reach {
-            mm.cant_reach_walk_target_since.clear();
-        } else if !mm.cant_reach_walk_target_since.present() {
-            mm.cant_reach_walk_target_since.set(cx.now);
+            since.clear();
+        } else if !since.present() {
+            since.set(now);
         }
         if path.is_some() {
             return true;
@@ -3178,14 +3144,14 @@ fn compute_path(
             f64::from(target[2]) + 0.5,
         ];
         if let Some(step) =
-            m.default_random_pos_towards(cx.w, 10, 7, to, f64::from(std::f32::consts::FRAC_PI_2))
+            m.default_random_pos_towards(w, 10, 7, to, f64::from(std::f32::consts::FRAC_PI_2))
         {
             let p = [
                 step[0].floor() as i32,
                 step[1].floor() as i32,
                 step[2].floor() as i32,
             ];
-            *path = m.create_path_to(cx.w, p, 0);
+            *path = m.create_path_to(w, p, 0);
             return path.is_some();
         }
     }

crates/horizon-client/src/mobs/warden_brain.rs

@@ -14,9 +14,10 @@
 //! shuffle seed.
 use super::{
     Mob, MobEvent, MobWorld, Who,
+    brain::Timed,
     goals::Cx,
     path::Path,
-    villager_brain::{Slot, Tracker, Visible, WalkTarget},
+    villager_brain::{Slot, Tracker, Visible, WalkTarget, compute_path, reached},
     warden::{self, Pose},
 };
 use horizon_core::{
@@ -145,31 +146,6 @@ impl Memories {
     }
 }
 
-/// `Behavior`'s bookkeeping: running, and until when.
-#[derive(Clone, Debug)]
-struct Timed {
-    running: bool,
-    end: i64,
-    min: i32,
-    max: i32,
-}
-impl Timed {
-    fn new(min: i32, max: i32) -> Self {
-        Self {
-            running: false,
-            end: 0,
-            min,
-            max,
-        }
-    }
-    /// `Behavior.tryStart`'s duration draw (made even when it cannot vary).
-    fn begin(&mut self, cx: &mut Bx) {
-        self.running = true;
-        let d = self.min + cx.lr.next_int_bound(self.max + 1 - self.min).unwrap_or(0);
-        self.end = cx.now + i64::from(d);
-    }
-}
-
 /// `RunOne`'s `ShufflingList` over a stroll (weight 2) and `DoNothing` (1).
 #[derive(Clone, Debug)]
 struct Gate {
@@ -383,6 +359,10 @@ fn brain(m: &Mob) -> Option<&Brain> {
 pub(super) fn mem(m: &mut Mob) -> &mut Memories {
     &mut m.extra.warden.as_mut().expect("a warden").brain.mem
 }
+/// `CANT_REACH_WALK_TARGET_SINCE`, for `compute_path`.
+fn cant_reach(m: &mut Mob) -> &mut Slot<i64> {
+    &mut mem(m).cant_reach_walk_target_since
+}
 pub(super) fn mem_ref(m: &Mob) -> Option<&Memories> {
     brain(m).map(|b| &b.mem)
 }
@@ -558,9 +538,6 @@ fn find_closest(m: &mut Mob, w: &MobWorld, filter: impl Fn(&Mob, Who) -> bool) -
 fn block_of(p: Vec3) -> [i32; 3] {
     [p.x.floor() as i32, p.y.floor() as i32, p.z.floor() as i32]
 }
-fn manhattan(a: [i32; 3], b: [i32; 3]) -> i32 {
-    (a[0] - b[0]).abs() + (a[1] - b[1]).abs() + (a[2] - b[2]).abs()
-}
 fn dist_sqr(a: [i32; 3], b: [i32; 3]) -> i64 {
     (0..3).map(|i| i64::from(a[i] - b[i]).pow(2)).sum()
 }
@@ -607,57 +584,6 @@ fn tracker_visible(m: &mut Mob, w: &MobWorld, t: Tracker) -> bool {
         _ => true,
     }
 }
-/// `MoveToTargetSink.reachedTarget`.
-fn reached(m: &Mob, w: &MobWorld, walk: &WalkTarget) -> bool {
-    walk.target
-        .block(w)
-        .is_some_and(|p| manhattan(p, block_of(m.position)) <= walk.close)
-}
-/// `MoveToTargetSink.tryComputePath`.
-fn compute_path(
-    m: &mut Mob,
-    cx: &mut Bx,
-    walk: &WalkTarget,
-    path: &mut Option<Path>,
-    speed: &mut f32,
-) -> bool {
-    let Some(target) = walk.target.block(cx.w) else {
-        return false;
-    };
-    *path = m.create_path_to(cx.w, target, 0);
-    *speed = walk.speed;
-    if reached(m, cx.w, walk) {
-        mem(m).cant_reach_walk_target_since.clear();
-    } else {
-        let can_reach = path.as_ref().is_some_and(|p| p.reached);
-        let mm = mem(m);
-        if can_reach {
-            mm.cant_reach_walk_target_since.clear();
-        } else if !mm.cant_reach_walk_target_since.present() {
-            mm.cant_reach_walk_target_since.set(cx.now);
-        }
-        if path.is_some() {
-            return true;
-        }
-        let to = [
-            f64::from(target[0]) + 0.5,
-            f64::from(target[1]),
-            f64::from(target[2]) + 0.5,
-        ];
-        if let Some(step) =
-            m.default_random_pos_towards(cx.w, 10, 7, to, f64::from(std::f32::consts::FRAC_PI_2))
-        {
-            let p = [
-                step[0].floor() as i32,
-                step[1].floor() as i32,
-                step[2].floor() as i32,
-            ];
-            *path = m.create_path_to(cx.w, p, 0);
-            return path.is_some();
-        }
-    }
-    false
-}
 fn same_path(a: Option<&Path>, b: Option<&Path>) -> bool {
     match (a, b) {
         (None, None) => true,
@@ -710,7 +636,7 @@ impl B {
                 if !swim_condition(m) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::SetWardenLookTarget(r) => one(r, || {
@@ -732,7 +658,7 @@ impl B {
                 if !mem(m).look_target.present() {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::MoveToTargetSink {
@@ -755,9 +681,9 @@ impl B {
                     return false;
                 };
                 let reached = reached(m, cx.w, &walk);
-                if !reached && compute_path(m, cx, &walk, path, speed) {
+                if !reached && compute_path(m, cx.w, cx.now, &walk, path, speed, cant_reach) {
                     *last_target = walk.target.block(cx.w);
-                    t.begin(cx);
+                    t.begin(cx.lr, cx.now);
                     // start
                     mem(m).path.set_opt(path.clone());
                     m.nav_move_to_path(path.clone(), f64::from(*speed));
@@ -775,7 +701,7 @@ impl B {
                 if !mm.is_emerging.present() || mm.walk_target.present() {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 warden::set_pose(m, Pose::Emerging);
                 sound(m, "entity.warden.emerge", 5.0, 1.0, cx.events);
                 true
@@ -791,7 +717,7 @@ impl B {
                 if !(m.on_ground || liquid) {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 if m.on_ground {
                     warden::set_pose(m, Pose::Digging);
                     sound(m, "entity.warden.dig", 5.0, 1.0, cx.events);
@@ -872,7 +798,7 @@ impl B {
                 true
             }),
             B::DoNothing(t) => {
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 true
             }
             B::GoToDisturbance(r) => one(r, || {
@@ -907,7 +833,7 @@ impl B {
                 {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 sound(m, "entity.warden.sniff", 5.0, 1.0, cx.events);
                 true
             }
@@ -919,7 +845,7 @@ impl B {
                 let Some(target) = mm.roar_target.value() else {
                     return false;
                 };
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 let mm = mem(m);
                 mm.roar_sound_delay.set_ttl((), ROAR_SOUND_DELAY);
                 mm.walk_target.clear();
@@ -1004,7 +930,7 @@ impl B {
                 if !close {
                     return false;
                 }
-                t.begin(cx);
+                t.begin(cx.lr, cx.now);
                 let mm = mem(m);
                 mm.attack_cooling_down
                     .set_ttl(true, i64::from(SONIC_DURATION));
@@ -1092,7 +1018,7 @@ impl B {
                     && let Some(walk) = mem(m).walk_target.value()
                     && let Some(now_target) = walk.target.block(cx.w)
                     && dist_sqr(now_target, last) > 4
-                    && compute_path(m, cx, &walk, path, speed)
+                    && compute_path(m, cx.w, cx.now, &walk, path, speed, cant_reach)
                 {
                     *last_target = Some(now_target);
                     mem(m).path.set_opt(path.clone());

crates/horizon-client/src/particles.rs

@@ -1336,6 +1336,16 @@ impl ParticleEngine {
             ParticleType::ExplosionEmitter
         };
         self.add(&ParticleOptions::simple(ty), center, [1.0, 0.0, 0.0]);
+        self.explosion_blocks(center, radius, block_count, is_air);
+    }
+    /// `ClientExplosionTracker` with `Level.DEFAULT_EXPLOSION_BLOCK_PARTICLES`.
+    pub fn explosion_blocks(
+        &mut self,
+        center: [f64; 3],
+        radius: f32,
+        block_count: usize,
+        is_air: &dyn Fn([i32; 3]) -> bool,
+    ) {
         for _ in 0..block_count.min(512) {
             let r = &mut self.random;
             let d = Vec3::new(

crates/horizon-protocol/src/item.rs

@@ -32,6 +32,7 @@ pub mod component {
     pub const DYED_COLOR: i32 = 47;
     pub const MAP_ID: i32 = 48;
     pub const MAP_POST_PROCESSING: i32 = 50;
+    pub const CHARGED_PROJECTILES: i32 = 51;
     pub const WRITABLE_BOOK_CONTENT: i32 = 56;
     pub const WRITTEN_BOOK_CONTENT: i32 = 57;
 }
@@ -75,6 +76,8 @@ pub enum Component {
     /// `WritableBookContent`: the pages (raw text).
     WritableBook(Vec<String>),
     WrittenBook(WrittenBook),
+    /// `ChargedProjectiles`: a loaded crossbow's ammunition, as templates.
+    Stacks(Vec<Stack>),
 }
 
 /// `Filterable.streamCodec`: the raw value, then an optional filtered one
@@ -125,6 +128,10 @@ impl Component {
                     resolved: r.bool()?,
                 })
             }
+            CHARGED_PROJECTILES => {
+                let n = r.count(1024)?;
+                Self::Stacks((0..n).map(|_| Template::read(r)).collect::<Result<_>>()?)
+            }
             DYED_COLOR => Self::Int(r.i32()?),
             UNBREAKABLE | CREATIVE_SLOT_LOCK => Self::Unit,
             ENCHANTMENT_GLINT_OVERRIDE => Self::Bool(r.bool()?),
@@ -283,6 +290,10 @@ impl Component {
                 w.varint(hidden.len() as i32);
                 hidden.iter().for_each(|h| w.varint(*h));
             }
+            Self::Stacks(stacks) => {
+                w.varint(stacks.len() as i32);
+                stacks.iter().for_each(|s| Template::write(s, w));
+            }
             Self::WritableBook(pages) => {
                 w.varint(pages.len() as i32);
                 for page in pages {
@@ -533,6 +544,21 @@ mod tests {
         round::<Option<Hashed>, HashedSlot>(None);
     }
 
+    #[test]
+    fn charged_projectiles_are_item_stack_templates() {
+        // A crossbow (id 7) loaded with one arrow (id 9): ChargedProjectiles
+        // is a list of ItemStackTemplate, the item before the count.
+        let bytes = [1, 7, 1, 0, 51, 1, 9, 1, 0, 0];
+        let stack = Slot::read(&mut Reader::new(&bytes)).unwrap().unwrap();
+        assert_eq!(
+            stack.component(component::CHARGED_PROJECTILES),
+            Some(&Component::Stacks(vec![Stack::new(9, 1)]))
+        );
+        let mut w = Writer::new();
+        Slot::write(&Some(stack), &mut w);
+        assert_eq!(w.data, bytes);
+    }
+
     #[test]
     fn filtered_book_pages_are_read_and_dropped() {
         // A writable book with one page "hi" and its filtered "**".

crates/horizon-protocol/src/packets/play.rs

@@ -461,6 +461,15 @@ packet!(OpenScreen { container: i32 => VarInt, menu: i32 => VarInt, title: Tag =
 // ClientboundMountScreenOpenPacket: a horse's or llama's inventory, with its
 // chest's columns (`getInventoryColumns`).
 packet!(MountScreenOpen { container: i32 => VarInt, columns: i32 => VarInt, entity: i32 => Int });
+packet!(
+    /// ClientboundOpenSignEditorPacket: the sign whose side the player edits.
+    OpenSignEditor { pos: [i32; 3] => Pos, front: bool => SignSide }
+);
+packet!(
+    /// ClientboundOpenBookPacket: the hand (InteractionHand, 0 main, 1 off)
+    /// whose written book the player reads.
+    OpenBook { hand: i32 => VarInt }
+);
 packet!(PlayerAbilities { flags: i8 => Byte, flying_speed: f32 => Float, walking_speed: f32 => Float });
 /// MessageSignature.Packed: an index into the last-seen cache or a full signature.
 pub struct PackedSignature;
@@ -1617,6 +1626,8 @@ packet_enum!(Clientbound, crate::ids::play::clientbound {
     MerchantOffers(MerchantOffers) = MERCHANT_OFFERS,
     MountScreenOpen(MountScreenOpen) = MOUNT_SCREEN_OPEN,
     OpenScreen(OpenScreen) = OPEN_SCREEN,
+    OpenBook(OpenBook) = OPEN_BOOK,
+    OpenSignEditor(OpenSignEditor) = OPEN_SIGN_EDITOR,
     Ping(Ping) = PING,
     PongResponse(crate::packets::status::Ping) = PONG_RESPONSE,
     PlayerAbilities(PlayerAbilities) = PLAYER_ABILITIES,
@@ -1917,6 +1928,61 @@ packet!(
     /// ServerboundRenameItemPacket: `AnvilMenu.setItemName`.
     RenameItem { name: String => Str }
 );
+packet!(
+    /// ServerboundSignUpdatePacket: the four lines the player wrote on a side.
+    SignUpdate { pos: [i32; 3] => Pos, lines: [String; 4] => SignLines, front: bool => SignSide }
+);
+packet!(
+    /// ServerboundEditBookPacket: the book's slot (a hotbar slot, or 40 for
+    /// the off hand), its pages and, to sign it, its title.
+    EditBook {
+        slot: i32 => VarInt,
+        pages: Vec<String> => BookPages,
+        title: Option<String> => Opt<StrN<32>>,
+    }
+);
+/// `stringUtf8(1024)` in `list(100)`: a book's pages.
+pub struct BookPages;
+impl Codec<Vec<String>> for BookPages {
+    fn read(r: &mut Reader) -> Result<Vec<String>> {
+        let n = r.varint()?;
+        if !(0..=100).contains(&n) {
+            return Err(Error::new(format!("{n} book pages, at most 100")));
+        }
+        (0..n).map(|_| r.string(1024)).collect()
+    }
+    fn write(v: &Vec<String>, w: &mut Writer) {
+        List::<StrN<1024>>::write(v, w);
+    }
+}
+/// SignTextSlot.STREAM_CODEC: VarInt 0 for the back, 1 for the front (any
+/// other id reads as the back, ByIdMap's ZERO strategy).
+pub struct SignSide;
+impl Codec<bool> for SignSide {
+    fn read(r: &mut Reader) -> Result<bool> {
+        Ok(r.varint()? == 1)
+    }
+    fn write(v: &bool, w: &mut Writer) {
+        w.varint(i32::from(*v));
+    }
+}
+/// `stringUtf8(384)` in `fixedSizeList(4)`: four lines, no count.
+pub struct SignLines;
+impl Codec<[String; 4]> for SignLines {
+    fn read(r: &mut Reader) -> Result<[String; 4]> {
+        Ok([
+            r.string(384)?,
+            r.string(384)?,
+            r.string(384)?,
+            r.string(384)?,
+        ])
+    }
+    fn write(v: &[String; 4], w: &mut Writer) {
+        for line in v {
+            w.string(line);
+        }
+    }
+}
 packet!(
     /// ServerboundSetBeaconPacket: `BeaconMenu.updateEffects`, each power an
     /// optional `mob_effect` id.
@@ -2000,6 +2066,7 @@ packet_enum!(Serverbound, crate::ids::play::serverbound {
     ContainerClick(ContainerClick) = CONTAINER_CLICK,
     ContainerClose(ContainerClose) = CONTAINER_CLOSE,
     CustomPayload(CustomPayload) = CUSTOM_PAYLOAD,
+    EditBook(EditBook) = EDIT_BOOK,
     Interact(Interact) = INTERACT,
     KeepAlive(KeepAlive) = KEEP_ALIVE,
     MovePlayerPos(MovePlayerPos) = MOVE_PLAYER_POS,
@@ -2024,6 +2091,7 @@ packet_enum!(Serverbound, crate::ids::play::serverbound {
     SetBeacon(SetBeacon) = SET_BEACON,
     SetCarriedItem(SetCarriedItem) = SET_CARRIED_ITEM,
     SetCreativeModeSlot(SetCreativeModeSlot) = SET_CREATIVE_MODE_SLOT,
+    SignUpdate(SignUpdate) = SIGN_UPDATE,
     UseItem(UseItem) = USE_ITEM,
     UseItemOn(UseItemOn) = USE_ITEM_ON,
 });
@@ -2748,4 +2816,48 @@ mod tests {
         });
         round_trip(p, Clientbound::encode, Clientbound::decode);
     }
+
+    #[test]
+    fn sign_packets_match_vanilla_stream_codecs() {
+        // ClientboundOpenSignEditorPacket: BlockPos, then SignTextSlot as a VarInt (FRONT is 1).
+        let open = Clientbound::OpenSignEditor(OpenSignEditor {
+            pos: [1, 2, 3],
+            front: true,
+        });
+        let body = open.encode();
+        assert_eq!(
+            body[1..9],
+            crate::buf::pack_block_pos([1, 2, 3]).to_be_bytes()
+        );
+        assert_eq!(body[9..], [1]);
+        round_trip(open, Clientbound::encode, Clientbound::decode);
+        // ServerboundSignUpdatePacket: BlockPos, four strings with no count, then the slot.
+        let update = Serverbound::SignUpdate(SignUpdate {
+            pos: [-4, 70, 9],
+            lines: ["Hi".into(), String::new(), "x".into(), String::new()],
+            front: false,
+        });
+        let body = update.encode();
+        assert_eq!(body[9..], [2, b'H', b'i', 0, 1, b'x', 0, 0]);
+        round_trip(update, Serverbound::encode, Serverbound::decode);
+    }
+
+    #[test]
+    fn book_packets_match_vanilla_stream_codecs() {
+        // ClientboundOpenBookPacket: InteractionHand as a VarInt.
+        let open = Clientbound::OpenBook(OpenBook { hand: 1 });
+        assert_eq!(open.encode()[1..], [1]);
+        round_trip(open, Clientbound::encode, Clientbound::decode);
+        // ServerboundEditBookPacket: the slot, the pages (a counted list), then an optional title.
+        let sign = Serverbound::EditBook(EditBook {
+            slot: 40,
+            pages: vec!["a".into(), String::new()],
+            title: Some("T".into()),
+        });
+        assert_eq!(sign.encode()[1..], [40, 2, 1, b'a', 0, 1, 1, b'T']);
+        round_trip(sign, Serverbound::encode, Serverbound::decode);
+        let mut w = Writer::new();
+        w.varint(101);
+        assert!(BookPages::read(&mut Reader::new(&w.data)).is_err());
+    }
 }

crates/horizon-shaderpack/src/lib.rs

@@ -182,6 +182,22 @@ impl JavaPack {
     }
 }
 
+impl JavaPack {
+    /// The block ids of the pack's `block.properties` (empty without one),
+    /// [`properties::block_ids`].
+    pub fn block_ids(
+        &self,
+        values: &OptionValues,
+        env: &Environment,
+    ) -> Result<BTreeMap<String, i32>, String> {
+        match self.files.read("block.properties") {
+            Some(text) => properties::block_ids(&text, env, &self.options, values)
+                .map_err(|e| format!("block.properties: {e}")),
+            None => Ok(BTreeMap::new()),
+        }
+    }
+}
+
 /// A program's name in `shaders.properties` (`world-1/composite1.fsh` is
 /// `world-1/composite1`).
 pub fn program_name(program: &str) -> &str {

crates/horizon-shaderpack/src/pipeline.rs

@@ -12,7 +12,7 @@ use crate::{
     options::OptionValues,
     preprocess::Environment,
     properties::{Blend, LEGACY_TARGETS, ShaderProperties},
-    translate::{Link, Translated},
+    translate::{Geometry, Link, Translated},
 };
 use std::collections::{BTreeMap, BTreeSet};
 
@@ -327,8 +327,33 @@ pub struct Passes {
     /// next frame starts unflipped.
     pub flipped_at_end: BTreeSet<u32>,
     pub directives: Directives,
+    /// The program Horizon's solid terrain is drawn with
+    /// ([`TERRAIN_PROGRAMS`]), before `deferred`.
+    pub terrain: Option<Pass>,
+    /// The program its translucent terrain is drawn with
+    /// ([`WATER_PROGRAMS`]), after `deferred`.
+    pub water: Option<Pass>,
 }
 
+/// The programs Iris draws solid terrain with, the first the pack has
+/// (`ProgramId.Terrain`'s fallbacks).
+pub const TERRAIN_PROGRAMS: &[&str] = &[
+    "gbuffers_terrain",
+    "gbuffers_textured_lit",
+    "gbuffers_textured",
+    "gbuffers_basic",
+];
+
+/// The programs Iris draws translucent terrain with (`ProgramId.Water`'s
+/// fallbacks).
+pub const WATER_PROGRAMS: &[&str] = &[
+    "gbuffers_water",
+    "gbuffers_terrain",
+    "gbuffers_textured_lit",
+    "gbuffers_textured",
+    "gbuffers_basic",
+];
+
 /// The `const` directives of a program folder that aren't about targets
 /// (`PackDirectives`), read from the same programs in the same order.
 #[derive(Clone, Copy, Debug, PartialEq)]
@@ -554,6 +579,25 @@ impl JavaPack {
         out.flipped_after_translucent = flipped.clone();
         out.composite = run(&groups[3], "composite_pre", &mut flipped)?;
         out.flipped_at_end = flipped;
+        // Geometry writes the side the next passes read.
+        let geometry = |chain: &[&str], flipped: &BTreeSet<u32>| {
+            let Some(name) = chain.iter().find(|n| exists(n)) else {
+                return Ok::<_, String>(None);
+            };
+            let text = fragment(name)?;
+            let (blend, buffer_blends) = resolve_blends(&path(name));
+            Ok(Some(Pass {
+                program: path(name),
+                draw_buffers: draw_buffers(&text).map_err(|e| format!("{}: {e}", path(name)))?,
+                reads_alt: flipped.clone(),
+                mipmapped: BTreeSet::new(),
+                scale: 1.0,
+                blend,
+                buffer_blends,
+            }))
+        };
+        out.terrain = geometry(TERRAIN_PROGRAMS, &out.flipped_after_prepare)?;
+        out.water = geometry(WATER_PROGRAMS, &out.flipped_after_translucent)?;
         if exists("final") {
             let prog = path("final");
             let (blend, buffer_blends) = resolve_blends(&prog);
@@ -614,6 +658,70 @@ impl JavaPack {
     }
 }
 
+/// A geometry program translated: the program (its vertex with the first
+/// glue), and its vertex with each other glue.
+pub struct GeometryProgram {
+    pub program: Program,
+    pub variants: Vec<Translated>,
+}
+
+impl JavaPack {
+    /// Translate geometry program `pass` (`gbuffers_*`) to run over
+    /// Horizon's geometry: its bindings in group 2, its attributes from
+    /// each of `glues` (the vertex program is translated once per glue).
+    #[allow(clippy::too_many_arguments)]
+    pub fn compile_geometry(
+        &self,
+        pass: &Pass,
+        targets: &[TargetSettings],
+        values: &OptionValues,
+        env: &Environment,
+        properties: &ShaderProperties,
+        glues: &[Geometry],
+    ) -> Result<GeometryProgram, String> {
+        let (first, rest) = glues
+            .split_first()
+            .ok_or("a geometry program needs a glue")?;
+        let mut link = Link {
+            image_formats: properties.image_formats(),
+            shared_samplers: shared_samplers(targets),
+            set: 2,
+            geometry: Some(first.clone()),
+            ..Link::default()
+        };
+        let vertex = self.translate(&format!("{}.vsh", pass.program), values, env, &mut link)?;
+        let fragment = self.translate(&format!("{}.fsh", pass.program), values, env, &mut link)?;
+        let mut variants = Vec::new();
+        for glue in rest {
+            let mut other = link.clone();
+            other.geometry = Some(glue.clone());
+            variants.push(self.translate(
+                &format!("{}.vsh", pass.program),
+                values,
+                env,
+                &mut other,
+            )?);
+            if other.uniforms != link.uniforms || other.bindings != link.bindings {
+                return Err(format!("{}: its variants bind differently", pass.program));
+            }
+        }
+        let draw_buffers = match &pass.draw_buffers {
+            Some(buffers) => buffers.clone(),
+            None => (0..fragment.interface.outputs.keys().max().map_or(1, |m| m + 1)).collect(),
+        };
+        Ok(GeometryProgram {
+            program: Program {
+                pass: pass.clone(),
+                vertex,
+                fragment,
+                draw_buffers,
+                link,
+            },
+            variants,
+        })
+    }
+}
+
 /// Iris's sampler states for the textures it binds: colour targets
 /// linear (nearest for integer formats, and for 32-bit floats, which wgpu
 /// can't filter everywhere), depth nearest, noise repeating. For

crates/horizon-shaderpack/src/properties.rs

@@ -639,6 +639,58 @@ impl ShaderProperties {
     }
 }
 
+/// `block.properties` (`block.<id>=<blocks>`), preprocessed as
+/// `shaders.properties` is: each block's id by its name without namespace
+/// (`oak_leaves`). A block listed with a state (`grass_block:snowy=true`)
+/// takes that id only when no entry names it without one; numeric ids
+/// (before 1.13) are skipped.
+pub fn block_ids(
+    text: &str,
+    env: &Environment,
+    options: &OptionSet,
+    values: &OptionValues,
+) -> Result<BTreeMap<String, i32>, String> {
+    let properties = Properties::parse(&preprocess(text, env, options, values)?);
+    let mut plain = BTreeMap::new();
+    let mut with_state = BTreeMap::new();
+    for (key, value) in properties.iter() {
+        let Some(Ok(id)) = key.strip_prefix("block.").map(str::parse::<i32>) else {
+            continue;
+        };
+        for entry in value.split_whitespace() {
+            let entry = entry.strip_prefix("minecraft:").unwrap_or(entry);
+            if entry.contains(':') && entry.split(':').nth(1).is_some_and(|s| s.contains('=')) {
+                let name = entry.split(':').next().unwrap_or(entry);
+                with_state.entry(name.to_owned()).or_insert(id);
+            } else if !entry.chars().all(|c| c.is_ascii_digit()) && !entry.contains('=') {
+                plain.insert(entry.to_owned(), id);
+            }
+        }
+    }
+    for (name, id) in with_state {
+        plain.entry(name).or_insert(id);
+    }
+    Ok(plain)
+}
+
+/// The block a block sprite (`minecraft:block/oak_log_top`) belongs to in
+/// `ids` ([`block_ids`]): the block named like it, else the longest one its
+/// name starts with followed by `_` (`oak_log`, `water` for `water_still`).
+pub fn sprite_block_id(sprite: &str, ids: &BTreeMap<String, i32>) -> Option<i32> {
+    let name = sprite.rsplit(['/', ':']).next()?;
+    if let Some(&id) = ids.get(name) {
+        return Some(id);
+    }
+    let mut end = name.len();
+    while let Some(cut) = name[..end].rfind('_') {
+        if let Some(&id) = ids.get(&name[..cut]) {
+            return Some(id);
+        }
+        end = cut;
+    }
+    None
+}
+
 /// Iris's `BooleanParser`: options joined by `!`, `&&`, `||` and brackets,
 /// `&&` binding tighter. `true`/`1` and `false`/`0` are literals; a name that
 /// isn't a boolean option is true; a malformed expression is true.
@@ -757,6 +809,42 @@ mod tests {
         set
     }
 
+    /// `block.properties` as Chocapic13' writes it, and sprites matched to
+    /// its blocks.
+    #[test]
+    fn block_ids_and_the_sprites_of_their_blocks() {
+        let text = "\
+#if MC_VERSION >= 11300
+block.10001= minecraft:wheat minecraft:short_grass
+block.10003 = minecraft:oak_leaves \\
+  minecraft:vine
+block.10006 = minecraft:grass_block:snowy=true minecraft:snow
+block.8 = minecraft:water
+block.2 = minecraft:grass_block
+#else
+block.10001= 6 31
+#endif
+layer.translucent=minecraft:glass
+";
+        let env = Environment {
+            defines: vec![("MC_VERSION".into(), "260300".into())],
+        };
+        let ids = block_ids(text, &env, &OptionSet::default(), &OptionValues::default()).unwrap();
+        assert_eq!(ids.get("vine"), Some(&10003));
+        // The stateless entry wins over the snowy one.
+        assert_eq!(ids.get("grass_block"), Some(&2));
+        assert!(!ids.contains_key("6") && !ids.contains_key("glass"));
+        for (sprite, id) in [
+            ("minecraft:block/oak_leaves", Some(10003)),
+            ("minecraft:block/water_still", Some(8)),
+            ("minecraft:block/grass_block_top", Some(2)),
+            ("minecraft:block/wheat_stage7", Some(10001)),
+            ("minecraft:block/stone", None),
+        ] {
+            assert_eq!(sprite_block_id(sprite, &ids), id, "{sprite}");
+        }
+    }
+
     #[test]
     fn java_properties_syntax() {
         let p = Properties::parse(

crates/horizon-shaderpack/src/translate.rs

@@ -45,7 +45,7 @@ use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 
 /// Locations, bindings and uniforms shared by the programs of one pass: a
 /// pass's vertex program is translated first, its fragment program second.
-#[derive(Default, Debug)]
+#[derive(Clone, Default, Debug)]
 pub struct Link {
     /// Varying name → location (split matrices and arrays as `name#i`).
     pub varyings: BTreeMap<String, u32>,
@@ -64,6 +64,27 @@ pub struct Link {
     /// 16). Once any is named, comparison samplers share `iris_compare` and
     /// integer ones `iris_nearest`; textures not named keep `{name}_s`.
     pub shared_samplers: BTreeMap<String, String>,
+    /// The bind group of the pack's bindings (0; 2 for geometry programs,
+    /// whose first groups are Horizon's).
+    pub set: u32,
+    /// Set for `gbuffers_*` programs drawn over Horizon's own geometry.
+    pub geometry: Option<Geometry>,
+}
+
+/// How a `gbuffers_*` program runs over Horizon's geometry: its vertex
+/// attributes aren't inputs but globals the glue fills from Horizon's
+/// vertices before the program's `main`.
+#[derive(Clone, Debug, Default)]
+pub struct Geometry {
+    /// GLSL put before the vertex program: Horizon's vertex inputs and
+    /// buffers, and a `void hz_vertex()` run first in `main`.
+    pub vertex_glue: String,
+    /// Each attribute's value as a `vec4` expression of the glue
+    /// (`iris_Vertex`, `mc_Entity`, `vaUV0`...). Others are zero.
+    pub attributes: BTreeMap<String, String>,
+    /// Iris's alpha test: the fragment is discarded unless output 0's
+    /// alpha is above it.
+    pub alpha_test: Option<f32>,
 }
 
 impl Link {
@@ -385,6 +406,7 @@ pub fn translate(
         .parse(&options, &glsl)
         .map_err(|e| first_lines(&e.emit_to_string(&glsl)))?;
     unpad_private_arrays(&mut module);
+    end_returning_cases(&mut module);
     let info = naga::valid::Validator::new(
         naga::valid::ValidationFlags::all(),
         naga::valid::Capabilities::all(),
@@ -403,6 +425,49 @@ pub fn translate(
     })
 }
 
+/// A `case` that ends with `return` or `discard` rather than `break`
+/// (Photon's displacement) is a fall-through one to naga's GLSL front end,
+/// which its WGSL writer refuses: nothing falls through it.
+fn end_returning_cases(module: &mut naga::Module) {
+    fn block(b: &mut naga::Block) {
+        for s in b.iter_mut() {
+            match s {
+                naga::Statement::Block(inner) => block(inner),
+                naga::Statement::If { accept, reject, .. } => {
+                    block(accept);
+                    block(reject);
+                }
+                naga::Statement::Loop {
+                    body, continuing, ..
+                } => {
+                    block(body);
+                    block(continuing);
+                }
+                naga::Statement::Switch { cases, .. } => {
+                    for case in cases {
+                        block(&mut case.body);
+                        if case.fall_through
+                            && matches!(
+                                case.body.last(),
+                                Some(naga::Statement::Return { .. } | naga::Statement::Kill)
+                            )
+                        {
+                            case.fall_through = false;
+                        }
+                    }
+                }
+                _ => {}
+            }
+        }
+    }
+    for (_, f) in module.functions.iter_mut() {
+        block(&mut f.body);
+    }
+    for e in &mut module.entry_points {
+        block(&mut e.function.body);
+    }
+}
+
 /// Built-in functions naga folds in `const` initialisers.
 const FOLDABLE: &[&str] = &[
     "radians",
@@ -634,6 +699,8 @@ struct Legaliser<'a> {
     mat2_ctor: bool,
     /// Constants turned into globals ([`needs_runtime`]).
     runtime_constants: HashSet<String>,
+    /// Geometry programs: each attribute's type, for the glue.
+    attribute_types: BTreeMap<String, String>,
 }
 
 fn var(name: &str) -> ast::Expr {
@@ -952,6 +1019,7 @@ impl<'a> Legaliser<'a> {
             gather: false,
             mat2_ctor: false,
             runtime_constants: HashSet::new(),
+            attribute_types: BTreeMap::new(),
         }
     }
 
@@ -1043,7 +1111,8 @@ impl<'a> Legaliser<'a> {
                 show_declaration(&mut text, d, &mut FormattingState::default())
                     .map_err(|e| e.to_string())?;
                 self.header.push(format!(
-                    "layout({kind}, set = 0, binding = {binding}) {}",
+                    "layout({kind}, set = {}, binding = {binding}) {}",
+                    self.link.set,
                     text.trim()
                 ));
                 Ok(false)
@@ -1099,7 +1168,8 @@ impl<'a> Legaliser<'a> {
                 for (name, _) in &names {
                     let t = self.link.binding(&format!("{name}_t"));
                     self.header.push(format!(
-                        "layout(set = 0, binding = {t}) uniform {texture} {name}_t;"
+                        "layout(set = {}, binding = {t}) uniform {texture} {name}_t;",
+                        self.link.set
                     ));
                     let shared = &self.link.shared_samplers;
                     let var = if shared.is_empty() {
@@ -1117,7 +1187,8 @@ impl<'a> Legaliser<'a> {
                     if self.sampler_vars.insert(var.clone()) {
                         let s = self.link.binding(&var);
                         self.header.push(format!(
-                            "layout(set = 0, binding = {s}) uniform {sampler} {var};"
+                            "layout(set = {}, binding = {s}) uniform {sampler} {var};",
+                            self.link.set
                         ));
                     }
                     self.interface
@@ -1156,7 +1227,8 @@ impl<'a> Legaliser<'a> {
                         .unwrap_or_else(|| "rgba8".to_owned());
                     let binding = self.link.binding(name);
                     layout.push(format!(
-                        "layout({f}, set = 0, binding = {binding}) {memory}uniform {ty} {name};"
+                        "layout({f}, set = {}, binding = {binding}) {memory}uniform {ty} {name};",
+                        self.link.set
                     ));
                     self.interface.images.push((name.clone(), f));
                 }
@@ -1199,10 +1271,8 @@ impl<'a> Legaliser<'a> {
             for (i, (name, array)) in names.iter().enumerate() {
                 let full_array = format!("{ty_array}{array}");
                 if input {
-                    let at = Link::location(&mut self.link.attributes, name);
-                    self.header.push(format!(
-                        "layout(location = {at}) in {ty} {name}{full_array};"
-                    ));
+                    let decl = self.attribute(&ty, name, &full_array);
+                    self.header.push(decl);
                     self.interface.attributes.insert(name.clone());
                 } else if !varying {
                     let at = explicit
@@ -1670,9 +1740,8 @@ impl<'a> Legaliser<'a> {
                 let ty = LEGACY_ATTRIBUTES.iter().find(|(a, _)| *a == n).unwrap().1;
                 let renamed = n.replacen("gl_", "iris_", 1);
                 if self.interface.attributes.insert(renamed.clone()) {
-                    let at = Link::location(&mut self.link.attributes, &renamed);
-                    self.header
-                        .push(format!("layout(location = {at}) in {ty} {renamed};"));
+                    let decl = self.attribute(ty, &renamed, "");
+                    self.header.push(decl);
                 }
                 renamed
             }
@@ -1694,6 +1763,21 @@ impl<'a> Legaliser<'a> {
         }
     }
 
+    /// A vertex attribute's declaration: an input, or for geometry programs
+    /// a global the glue fills ([`Geometry`]).
+    fn attribute(&mut self, ty: &str, name: &str, array: &str) -> String {
+        match &self.link.geometry {
+            Some(_) => {
+                self.attribute_types.insert(name.to_owned(), ty.to_owned());
+                format!("{ty} {name}{array};")
+            }
+            None => {
+                let at = Link::location(&mut self.link.attributes, name);
+                format!("layout(location = {at}) in {ty} {name}{array};")
+            }
+        }
+    }
+
     fn frag_data(&mut self, n: u32) -> ast::Expr {
         let name = format!("iris_FragData{n}");
         if self.interface.outputs.insert(n, name.clone()).is_none() {
@@ -1959,9 +2043,8 @@ impl<'a> Legaliser<'a> {
                 continue;
             }
             if attribute && self.stage == Stage::Vertex {
-                let at = Link::location(&mut self.link.attributes, name);
-                self.header
-                    .push(format!("layout(location = {at}) in {ty} {name};"));
+                let decl = self.attribute(ty, name, "");
+                self.header.push(decl);
                 self.interface.attributes.insert(name.to_owned());
             } else if !attribute {
                 self.link.uniform(name, format!("{ty} {name}"))?;
@@ -1971,6 +2054,42 @@ impl<'a> Legaliser<'a> {
         if !self.errors.is_empty() {
             return Err(self.errors.join("\n"));
         }
+        if let Some(geometry) = &self.link.geometry {
+            match self.stage {
+                Stage::Vertex => {
+                    // The glue first, then the attributes from it, before
+                    // the global initialisers (which may read them).
+                    let mut first = vec!["hz_vertex();".to_owned()];
+                    for (name, ty) in &self.attribute_types {
+                        first.push(match geometry.attributes.get(name) {
+                            Some(value) => format!("{name} = {ty}({value});"),
+                            None => format!("{name} = {ty}(0);"),
+                        });
+                    }
+                    self.prologue.splice(0..0, first);
+                }
+                Stage::Fragment => {
+                    if let (Some(reference), Some(name)) =
+                        (geometry.alpha_test, self.interface.outputs.get(&0))
+                    {
+                        let written = format!("iris_out_{name}");
+                        let name = if self.declared.contains(&written)
+                            || self
+                                .header
+                                .iter()
+                                .any(|h| h.ends_with(&format!(" {written};")))
+                        {
+                            written
+                        } else {
+                            name.clone()
+                        };
+                        self.epilogue
+                            .push(format!("if (!({name}.a > {reference:?})) discard;"));
+                    }
+                }
+                _ => {}
+            }
+        }
         if self.stage == Stage::Vertex {
             // GL's clip space to wgpu's: y flipped, so texture row 0 stays
             // the bottom of the picture as in GL (texture coordinates and
@@ -1982,6 +2101,10 @@ impl<'a> Legaliser<'a> {
         }
         let mut out = String::from("#version 450 core\n");
         out.push_str(HELPERS);
+        if let (Some(geometry), Stage::Vertex) = (&self.link.geometry, self.stage) {
+            out.push_str(&geometry.vertex_glue);
+            out.push('\n');
+        }
         if self.modulo {
             out.push_str(&modulo_helpers());
         }
@@ -1995,7 +2118,10 @@ impl<'a> Legaliser<'a> {
             out.push_str(MAT2_HELPERS);
         }
         if !self.link.uniforms.is_empty() {
-            out.push_str("layout(std140, set = 0, binding = 0) uniform IrisUniforms {\n");
+            out.push_str(&format!(
+                "layout(std140, set = {}, binding = 0) uniform IrisUniforms {{\n",
+                self.link.set
+            ));
             for (_, decl) in &self.link.uniforms {
                 out.push_str(&format!("    {decl};\n"));
             }

crates/horizon-shaderpack/tests/translate.rs

@@ -7,7 +7,7 @@ use horizon_shaderpack::{
     include::Inlined,
     preprocess::{Environment, preprocess},
     program_name,
-    translate::{Link, Translated, translate},
+    translate::{Geometry, Link, Translated, translate},
 };
 use std::collections::{BTreeMap, BTreeSet};
 
@@ -440,6 +440,95 @@ void main() {{
     );
 }
 
+/// A `gbuffers_*` program over Horizon's geometry: its attributes are
+/// globals the glue fills before `main`, its bindings in group 2, and its
+/// fragment discards below Iris's alpha test. A `case` ending in `return`
+/// (Photon's displacement) isn't a fall-through for naga.
+#[test]
+fn geometry_programs_take_their_attributes_from_the_glue() {
+    let glue = Geometry {
+        vertex_glue: "layout(location = 0) in vec3 hz_position;
+layout(std430, set = 3, binding = 0) readonly buffer HzTable { int hz_table[]; };
+vec4 hz_pos;
+void hz_vertex() { hz_pos = vec4(hz_position, 1.0) + float(hz_table[0]); }"
+            .into(),
+        attributes: [
+            ("iris_Vertex".to_owned(), "hz_pos".to_owned()),
+            (
+                "mc_Entity".to_owned(),
+                "vec4(8.0, -1.0, 0.0, 0.0)".to_owned(),
+            ),
+        ]
+        .into(),
+        alpha_test: Some(0.1),
+    };
+    let mut link = Link {
+        set: 2,
+        geometry: Some(glue),
+        ..Link::default()
+    };
+    let vs = run(
+        Stage::Vertex,
+        "uniform sampler2D noisetex;
+attribute vec4 mc_Entity;
+attribute vec2 mc_midTexCoord;
+varying vec2 uv;
+vec3 sway(vec3 p, int id) {
+    switch (id) {
+        case 8:
+            return p + 1.0;
+        case 9:
+        case 10:
+            return p - 1.0;
+        default:
+            return p;
+    }
+}
+void main() {
+    uv = gl_MultiTexCoord0.xy + mc_midTexCoord;
+    gl_Position = gl_ModelViewProjectionMatrix * vec4(sway(gl_Vertex.xyz, int(mc_Entity.x)), 1.0);
+}
+",
+        &mut link,
+    )
+    .unwrap();
+    for wanted in [
+        "hz_vertex();",
+        "mc_Entity = vec4(vec4(8.0, -1.0, 0.0, 0.0));",
+        "iris_Vertex = vec4(hz_pos);",
+        "mc_midTexCoord = vec2(0);",
+        "set = 2, binding = 0) uniform IrisUniforms",
+    ] {
+        assert!(vs.glsl.contains(wanted), "{wanted}\n{}", vs.glsl);
+    }
+    // Horizon's vertex input is the only one.
+    assert_eq!(
+        io(&vs, false).into_keys().collect::<Vec<_>>(),
+        ["hz_position"]
+    );
+    reparse(&vs.wgsl).unwrap();
+    let fs = run(
+        Stage::Fragment,
+        "uniform sampler2D gtexture;
+varying vec2 uv;
+void main() {
+    /* DRAWBUFFERS:02 */
+    gl_FragData[0] = texture2D(gtexture, uv);
+    gl_FragData[1] = vec4(1.0);
+}
+",
+        &mut link,
+    )
+    .unwrap();
+    assert!(
+        fs.glsl.contains("if (!(iris_FragData0.a > 0.1)) discard;"),
+        "{}",
+        fs.glsl
+    );
+    assert!(fs.glsl.contains("set = 2, binding = "), "{}", fs.glsl);
+    reparse(&fs.wgsl).unwrap();
+}
+
 /// A fragment output narrower than its four-channel target (Steadfast's
 /// `final` writes `out vec3 color`) is written through a `vec4` with alpha 1:
 /// GL fills the missing channels, wgpu refuses the pipeline.

crates/horizon-world/src/datafix/chunk_flatten.rs

@@ -266,8 +266,8 @@ fn is_virtual(block: usize) -> bool {
     VIRTUAL.contains(&block)
 }
 
-/// `getSideMask`.
-fn side_mask(west: bool, east: bool, north: bool, south: bool) -> i32 {
+/// `getSideMask` (LeavesFix has the same copy).
+pub(super) fn side_mask(west: bool, east: bool, north: bool, south: bool) -> i32 {
     let mut s = 0;
     if north {
         if east {

crates/horizon-world/src/datafix/chunk_leaves.rs

@@ -6,6 +6,7 @@
 //! emulated here (`IntOpenHashSet` and the key order of an `Int2ObjectOpenHashMap`).
 use std::collections::{HashMap, HashSet};
 
+use super::chunk_flatten::side_mask;
 use super::dynamic::{as_int, as_long_stream, as_str, ceillog2, set};
 use crate::nbt::Tag;
 
@@ -355,32 +356,6 @@ fn get_index(x: i32, y: i32, z: i32) -> i32 {
     y << 8 | z << 4 | x
 }
 
-fn side_mask(west: bool, east: bool, north: bool, south: bool) -> i32 {
-    let mut s = 0;
-    if north {
-        if east {
-            s |= 2;
-        } else if west {
-            s |= 128;
-        } else {
-            s |= 1;
-        }
-    } else if south {
-        if west {
-            s |= 32;
-        } else if east {
-            s |= 8;
-        } else {
-            s |= 16;
-        }
-    } else if east {
-        s |= 4;
-    } else if west {
-        s |= 64;
-    }
-    s
-}
-
 /// `LeavesFix` over a chunk (`{Level: ...}`).
 pub(super) fn leaves_fix(chunk: &mut Tag) {
     let Some(level) = chunk.get_mut("Level") else {

docs/shader-packs.md

@@ -24,7 +24,8 @@ Both are off by default. With no pack selected the renderer draws exactly what i
 | Java shader packs: full-screen pass plan (`horizon_shaderpack::pipeline`: `DRAWBUFFERS`/`RENDERTARGETS`, `colortexN` formats and clearing, buffer flips, `blend.*`) | done: planned for the three test packs |
 | Java shader packs: full-screen passes drawn (`java_pack.rs`, `gfx/java_stages.rs`: `begin`, `prepare`, `deferred*`, `composite*`, `final` over Horizon's world) | first slice: BSL and Complementary run (below); `depthtex1`/`depthtex2` before translucent geometry, `blend.*`, PNG `texture.<stage>.*` and `texture.noise` |
 | Java shader packs: custom uniforms (`horizon_shaderpack::uniforms`), `sunPathRotation`, `clouds`/`sun`/`moon`, eye light, `wetness` | done for the full-screen passes (below) |
-| Java shader packs: `gbuffers_*`, `shadow`, `.dat` and resource-location textures, images, compute | planned |
+| Java shader packs: `gbuffers_terrain`, `gbuffers_water` (`gfx/java_terrain.rs`: Horizon's terrain fed to the pack's programs) | first slice: MakeUp Ultra Fast, Chocapic13' and BSL draw their own terrain and water (below) |
+| Java shader packs: other `gbuffers_*`, `shadow`, `.dat` and resource-location textures, images, compute | planned |
 
 ## How the renderer draws a frame today
 
@@ -396,6 +397,25 @@ Picking one translates every planned pass of each dimension folder (`java_pack.r
 4. `final` draws into a target that replaces the world's picture, where Horizon packs' `composite` output goes: the
    hand, menus and HUD are drawn over it.
 
+When the pack has a `gbuffers_terrain` (or `textured_lit`, `textured`, `basic`, the program Iris falls back to), the
+pack draws the terrain itself (`gfx/java_terrain.rs`): Horizon's world pass skips its own solid and translucent
+terrain, then
+
+- at step 2, after Horizon's sky, entities and the rest enter `colortex0` and depth, the pack's terrain program draws
+  every visible section into its `RENDERTARGETS` (the side the next pass reads), tested against that depth; the
+  depth is then copied into `depthtex0` and `depthtex1`;
+- before the first `composite`, as Iris does, `gbuffers_water` (or the terrain program) draws the translucent
+  layer with the pack's `blend.*` or vanilla's blending; the depth goes into `depthtex0` only.
+
+The pack's vertex program reads Horizon's own terrain vertices (the arena pages, instanced or flat draws): a glue
+function written before `main` decodes them into Iris's attributes (`vaPosition`/`gl_Vertex` relative to the camera,
+`gl_Color` with vanilla's face shading undone, `gl_MultiTexCoord0/1`, the normal and `at_tangent` from the quad's
+four corners, `mc_midTexCoord`, `at_midBlock`), and `mc_Entity.x` is the block's id from the pack's
+`block.properties`, matched to the sprite's block by name. `gtexture`/`texture` is a 2D atlas built from Horizon's
+sprite arrays (animated sprites copied in each frame), `lightmap` is Horizon's lightmap with Iris's texture matrix,
+and fragments under alpha 0.1 are discarded (`alphaTestRef`). `RGBA16` targets are 16-bit unorm where the GPU can
+render them (Chocapic13' packs its G-buffer into them; half floats broke it).
+
 What makes Horizon look like OpenGL to the pack:
 
 - **Layout.** The translator ends every vertex shader by flipping `gl_Position.y` and moving depth from `[-w, w]` to
@@ -426,12 +446,15 @@ What makes Horizon look like OpenGL to the pack:
 
 Measured on the Mac mini (M4 Pro) with the packs' default options: BSL v10.1.8 and Complementary Reimagined r5.9.3
 grade and light Horizon's world as their post-processing would. Sildur's Vibrant v2.02 draws only its sky: its
-`deferred` reads the albedo `gbuffers_*` write to `colortex4`. Without `gbuffers_*` and `shadow`, no pack has its
-shadows, water or sky look yet; Distant Horizons' and Voxy's depth read as far. Horizon's world goes into the target
-the pack's `gbuffers_terrain` (or the program Iris falls back to) draws to first: `colortex0` for most packs,
-`colortex1` for MakeUp. Not supported yet: images and compute (`.csh`; a pack that needs them doesn't load),
-mipmapped targets (`colortexNMipmapEnabled` is read but ignored), `.dat` and resource-location custom textures (PNG
-files in the pack only); shadow matrices are identity.
+`deferred` reads the albedo `gbuffers_*` write to `colortex4` (not checked again since the terrain programs run).
+Without the other `gbuffers_*` and `shadow`, no pack has its shadows or sky look yet; Distant Horizons' and Voxy's
+depth read as far. Horizon's world goes into the target the pack's `gbuffers_terrain` (or the program Iris falls back
+to) draws to first: `colortex0` for most packs, `colortex1` for MakeUp. Not supported yet: images and compute (`.csh`;
+a pack that needs them doesn't load), mipmapped targets (`colortexNMipmapEnabled` is read but ignored), `.dat` and
+resource-location custom textures (PNG files in the pack only); shadow matrices are identity. With the pack's terrain:
+entities, the sky, the hand, weather and clouds are still Horizon's (in that first target only), GPU occlusion culling
+is off, block ids come from sprite names rather than block states, distant (LOD) terrain doesn't repeat its textures,
+and only the overworld has been checked.
 
 ### Compatibility
 
@@ -439,19 +462,19 @@ Tested on 2026-10-22 on the Mac mini (M4 Pro, Metal) with each pack's default op
 the authors' pages (dev-only test inputs, kept outside the repository). "Loads" means every pass the pack enables for
 the overworld, Nether and End is preprocessed, translated and validated, as the game does when the pack is picked
 (`java_pack::tests::real_packs_load` with `HORIZON_TEST_SHADERPACKS`); "drawn" means it was also picked in the game
-and screenshotted. Only full-screen passes run (above), so no pack has its own terrain, water, shadows or sky yet.
-The MakeUp, Chocapic13' and Photon rows are from 2026-10-23, on Metal and on Vulkan (RTX 4080).
+and screenshotted. Full-screen passes, `gbuffers_terrain` and `gbuffers_water` run (above); no pack has its own
+shadows, entities or sky yet.
 
 | Pack | Version | Result | First thing that stops it |
 | --- | --- | --- | --- |
-| BSL | v10.1.8 | drawn: 26 passes | |
+| BSL | v10.1.8 | drawn: 26 passes and its terrain and water programs | |
 | Complementary Reimagined | r5.9.3 | drawn: 27 passes | |
 | Complementary Unbound | r5.8 | loads: 27 passes | |
 | Sildur's Vibrant Extreme | 2.02 | drawn: 18 passes, only its sky (above) | |
 | Steadfast | 0.8.0 | drawn: 3 passes | |
-| MakeUp Ultra Fast | 9.6 | drawn: 6 passes, its fog, light shafts and grade over Horizon's world | |
-| Chocapic13' | V9 High | drawn: 16 passes; its default TAA upscaling shrinks the world in its `gbuffers_*` vertex programs, which don't run, so the picture is magnified 1/0.7: turn TAA Upscaling off in its settings | |
-| Photon | v1.4 | loads: 27 passes; draws black: it lights the scene from the G-buffer its `gbuffers_*` write | |
+| Chocapic13' | V9 High | drawn: 16 passes and its terrain and water programs | |
+| MakeUp Ultra Fast | 9.6 | drawn: 6 passes and its terrain and water programs | |
+| Photon | v1.4 | loads: 27 passes and its terrain and water programs; draws black | its sky and light come from a compute pass and `.dat` look-up tables, not loaded yet |
 | Bliss | 2.1.2 | fails | `world0/composite1.fsh`: a vector component passed to an `inout` parameter (WGSL can't point at one) |
 | Bloop | 1.8.0-Alpha-3 | fails | `world0/prepare1.fsh`: `mat2(vec4)` and other constructors naga's GLSL front end refuses |
 | Noble | v1.9.9 | fails (Apple and NVIDIA) | `world0/deferred4.vsh`: a `vec3[9][9]` varying (nested arrays between stages) |
@@ -492,9 +515,9 @@ What the translator does for these packs, as Iris (JCPP and its GLSL transformer
 3. **Full-screen programs**: `deferred*`, `composite*`, `final` with `colortex0..15` (formats from the pack),
    `depthtex0..2`, `noisetex` and the uniforms (most are already computed for the world shaders). This alone runs
    Sildur's and BSL post-processing over Horizon's own world.
-4. **`gbuffers_terrain`, `gbuffers_water`, `gbuffers_sky*`**: Horizon's terrain vertices extended with Iris's
-   attributes (`mc_Entity` from `block.properties`, `mc_midTexCoord`, `at_tangent`, lightmap), a second set of
-   terrain pipelines writing the pack's render targets.
+4. **`gbuffers_terrain`, `gbuffers_water`** (done, above), **`gbuffers_sky*`**: Horizon's terrain vertices decoded
+   into Iris's attributes (`mc_Entity` from `block.properties`, `mc_midTexCoord`, `at_tangent`, lightmap), a second
+   set of terrain pipelines writing the pack's render targets.
 5. **Entities, block entities, hand, weather, clouds, particles** `gbuffers_*`.
 6. **Shadow pass**: terrain and entities from the sun into `shadowtex0/1` and `shadowcolor0/1`, culled from the
    light's view, with the pack's distortion.

tools/lan_e2e.py

@@ -189,6 +189,27 @@ address. The script then checks, from both sides, what a guest's game used to ge
 - totem:     the host and the guest each take a lethal hit holding a totem of undying in the off
              hand, then the main hand: the server uses it up and keeps them alive at 1 health with its
              effects, and each side hears the totem once (entity event 35) (#1292).
+- keepinv:   the host and the guest each die holding diamonds and wearing a helmet: with keep_inventory
+             off both drop where they died and the player respawns without them; with it on nothing
+             drops and the player keeps them (#1284).
+- signs:     the host and the guest each place an oak sign: the editor opens on their own screen
+             (ClientboundOpenSignEditorPacket), the two lines they write reach the server
+             (ServerboundSignUpdatePacket) and both sides show them (#1380).
+- books:     the host and the guest each write in a book and quill on their own screen, sign it
+             (ServerboundEditBookPacket), read the written book the server gave them
+             (ClientboundOpenBookPacket), then drop it: the other side sees its title, author and
+             page (#1366).
+- elytra:    the host and the guest, high up with an Elytra on, jump in the air and glide
+             (ServerboundPlayerCommandPacket START_FALL_FLYING): both their client and the server
+             have them gliding, they go forward far more than down, and the glide ends on both once
+             they land (#1288).
+- helduse:   the host and the guest raise a shield, charge and fire a crossbow, throw a trident
+             and scope with a spyglass: each use starts on their own client and on the server, and
+             letting go ends it on both (RELEASE_USE_ITEM), so the shield lowers, the trident flies
+             and the loaded crossbow fires on the next use (#1300, #1281, #1282, #1301).
+- wind:      the host and the guest each throw a wind charge at their feet: the server's burst
+             launches them about six blocks up (the push in ClientboundExplodePacket) and they land
+             unhurt (#1386).
 
 Each check is reported on its own (a failing one doesn't stop the others) and the screenshots of
 both sides go to --out (host-*.png, guest-*.png).
@@ -4517,8 +4538,345 @@ def check_totem(host, guest, out):
     return seen
 
 
-CHECKS += ['totem']
-CHECK_FNS.update(totem=check_totem)
+def check_keep_inventory(host, guest, out):
+    """ServerPlayer.die's dropAllDeathLoot for each player (Player.dropEquipment): with keep_inventory
+    off, the diamonds and the helmet a player dies with lie where it died and it respawns with
+    neither; with it on, nothing drops and it respawns with both (#1284)."""
+    hx, hy, hz = (int(v // 1) for v in pos_of(host))
+    seen = {}
+    host('command', command=f'setworldspawn {hx} {hy} {hz}')
+    host('command', command='gamerule respawn_radius 0')
+    try:
+        for keep in ('false', 'true'):
+            host('command', command=f'gamerule keep_inventory {keep}')
+            for game, dz in ((host, -3), (guest, 3)):
+                # 14 blocks from the world spawn: nothing dropped is picked up on respawning.
+                x, z = hx + 14, hz + dz
+                host('command', command=f'fill {x - 2} {hy - 1} {z - 1} {x + 2} {hy - 1} {z + 1} minecraft:stone')
+                host('command', command=f'fill {x - 2} {hy} {z - 1} {x + 2} {hy + 2} {z + 1} minecraft:air')
+                host('command', command='kill @e[type=minecraft:item]')
+                game('command', command='gamemode survival')
+                game('command', command='clear @s')
+                game('command', command='give @s minecraft:diamond 7')
+                game('command', command='item replace entity @s armor.head with minecraft:iron_helmet')
+                game('command', command=f'tp @s {x + 0.5} {hy} {z + 0.5}')
+                game.wait(20)
+                game('command', command='kill @s')
+                game.wait(30)
+                dropped = sorted((e['item']['item'], e['item']['count'])
+                                 for e in game.raw('entities', 8, 'minecraft:item')['entities'])
+                game.shot(out, f'keepinv-{keep}')
+                respawn_when_ready(game)
+                game.wait(40)
+                back_to_game(game)
+                seen[f'{game.name}-keep-{keep}'] = {
+                    'dropped': dropped,
+                    'kept': {item: server_count(game, item) for item in ('diamond', 'iron_helmet')}}
+    finally:
+        host('command', command='gamerule keep_inventory false')
+        host('command', command='gamerule respawn_radius 10')
+        host('command', command='kill @e[type=minecraft:item]')
+        for game in (host, guest):
+            game('command', command='clear @s')
+        face_each_other(host, guest)
+    for case, s in seen.items():
+        want = ({'dropped': [], 'kept': {'diamond': 7, 'iron_helmet': 1}} if case.endswith('true') else
+                {'dropped': [('minecraft:diamond', 7), ('minecraft:iron_helmet', 1)],
+                 'kept': {'diamond': 0, 'iron_helmet': 0}})
+        assert s == want, f'{case}: {seen}'
+    return seen
+
+
+def check_signs(host, guest, out):
+    """SignBlock.openTextEdit on the placing player's client, for the host and the guest: placing
+    an oak sign opens its editor there and nowhere else, the lines typed into it go to the server
+    when it closes, and both sides then show them (#1380)."""
+    hx, hy, hz = (int(v // 1) for v in pos_of(host))
+    seen = {}
+    for game, other, dz in ((host, guest, -2), (guest, host, 2)):
+        spot = (hx + 2, hy, hz + dz)
+        game('command', command=f'setblock {spot[0]} {spot[1] - 1} {spot[2]} minecraft:stone')
+        game('command', command=f'setblock {spot[0]} {spot[1]} {spot[2]} minecraft:air')
+        game('command', command='gamemode survival')
+        game('command', command='clear @s')
+        game('command', command='give @s minecraft:oak_sign 1')
+        game.wait(10)
+        game.raw('place', *spot, '--item', 'minecraft:oak_sign')
+        game.wait(10)
+        opened = {g.name: g('state').get('screen') for g in (game, other)}
+        game.shot(out, 'signs-editor')
+        lines = [f'{game.name} wrote', 'line two']
+        game.raw('type', lines[0])
+        game.raw('key', 'enter', 'tap')
+        game.raw('type', lines[1])
+        game.raw('key', 'esc', 'tap')
+        game.wait(20)
+        back_to_game(other)
+        seen[game.name] = {'opened': opened,
+                           'shown': {g.name: (g.raw('block', *spot).get('sign') or {}).get('front')
+                                     for g in (game, other)}}
+        other.shot(out, 'signs-shown')
+    for name, s in seen.items():
+        other = 'guest' if name == 'host' else 'host'
+        want = [f'{name} wrote', 'line two', '', '']
+        assert s['opened'] == {name: 'sign', other: 'playing'}, f'{name}: {seen}'
+        assert s['shown'] == {name: want, other: want}, f'{name}: {seen}'
+    return seen
+
+
+def book_screen(game):
+    """The open book (`book`'s page and page count), once `game` shows it."""
+    game.raw('wait-for', 'screen', 'book', '--timeout', 10)
+    return game.raw('book')
+
+
+def check_books(host, guest, out):
+    """Books in hand for the host and the guest: a book and quill opens its editor on the player's
+    own client (LocalPlayer.openItemGui), what it writes and signs reaches the server
+    (ServerboundEditBookPacket), and the written book opens on the player's client when the server
+    says so (ServerPlayer.openItemGui's ClientboundOpenBookPacket); dropped, the other side sees the
+    server's book (#1366)."""
+    seen = {}
+    for game, other in ((host, guest), (guest, host)):
+        game('command', command='gamemode survival')
+        game('command', command='clear @s')
+        game('command', command='item replace entity @s weapon.mainhand with minecraft:writable_book')
+        x, y, z = pos_of(game)
+        game.raw('look-at', f'{x + 0.5:.2f}', f'{y + 30:.2f}', f'{z:.2f}')
+        game.wait(10)
+        case = seen[game.name] = {}
+        game.raw('use-item')
+        case['edit'] = book_screen(game)
+        case['other_screen'] = other('state').get('screen')
+        game.raw('type', f'{game.name} page one')
+        game.shot(out, 'books-edit')
+        game.raw('book', 'sign')
+        game.raw('type', f'{game.name} book')
+        game.raw('book', 'sign')
+        game.wait(20)
+        case['signed'] = {item: server_count(game, item) for item in ('writable_book', 'written_book')}
+        game.raw('use-item')
+        case['view'] = book_screen(game)
+        game.shot(out, 'books-view')
+        game.raw('book', 'done')
+        game.wait(5)
+        game.raw('key', 'q', 'tap')
+        game.wait(30)
+        books = [e['item'].get('components', '') for e in other.raw('entities', 16, 'minecraft:item')['entities']
+                 if e['item']['item'] == 'minecraft:written_book']
+        case['dropped'] = [all(f'{game.name} {t}' in c for t in ('page one', 'book')) for c in books]
+        host('command', command='kill @e[type=minecraft:item]')
+    for name, case in seen.items():
+        assert case['edit'] == {'page': 0, 'pages': 1, 'lectern': None}, f'{name}: {seen}'
+        assert case['other_screen'] == 'playing', f'{name}: {seen}'
+        assert case['signed'] == {'writable_book': 0, 'written_book': 1}, f'{name}: {seen}'
+        assert case['view'] == {'page': 0, 'pages': 1, 'lectern': None}, f'{name}: {seen}'
+        assert case['dropped'] == [True], f'{name}: {seen}'
+    return seen
+
+
+CHECKS += ['totem', 'keepinv', 'signs', 'books']
+CHECK_FNS.update(totem=check_totem, keepinv=check_keep_inventory, signs=check_signs, books=check_books)
+
+
+def check_elytra(host, guest, out):
+    """LivingEntity.updateFallFlying for each player: a jump while falling with an Elytra on starts a
+    glide that the server takes too (Player.tryToStartFallFlying), the glide carries the player
+    forward rather than down, and landing ends it on both sides (canGlide fails on the ground)."""
+    hx, hy, hz = (int(v // 1) for v in pos_of(host))
+    seen = {}
+    try:
+        for game, dx in ((host, -2), (guest, 2)):
+            x, z = hx + dx, hz
+            host('command', command=f'fill {x - 1} {hy - 1} {z - 1} {x + 1} {hy - 1} {z + 1} minecraft:stone')
+            host('command', command=f'fill {x - 1} {hy} {z - 1} {x + 1} {hy + 3} {z + 1} minecraft:air')
+            game('command', command='gamemode survival')
+            game('command', command='clear @s')
+            game('command', command='effect give @s minecraft:resistance 60 4 true')
+            game('command', command='item replace entity @s armor.chest with minecraft:elytra')
+            game('command', command=f'tp @s {x + 0.5} {hy + 60} {z + 0.5} 0 0')
+            game.wait(6)
+            start = pos_of(game)
+            game.raw('key', 'space', 'down')
+            game.wait(1)
+            game.raw('key', 'space', 'up')
+            game.wait(30)
+            end = pos_of(game)
+            glide = {'client': own(game).get('fall_flying'),
+                     'server': server_player(host, game).get('fall_flying'),
+                     'forward': round(math.hypot(end[0] - start[0], end[2] - start[2]), 1),
+                     'down': round(start[1] - end[1], 1)}
+            game.shot(out, 'elytra')
+            game('command', command=f'tp @s {x + 0.5} {hy + 1} {z + 0.5}')
+            game.wait(30)
+            landed = {'on_ground': own(game).get('on_ground'),
+                      'client': own(game).get('fall_flying'),
+                      'server': server_player(host, game).get('fall_flying')}
+            seen[game.name] = {'glide': glide, 'landed': landed}
+    finally:
+        for game in (host, guest):
+            game('command', command='clear @s')
+            game('command', command='effect clear @s')
+        face_each_other(host, guest)
+    for name, s in seen.items():
+        g, l = s['glide'], s['landed']
+        # Falling alone covers about 25 blocks in those 30 ticks and goes nowhere.
+        assert g['client'] and g['server'] and g['forward'] > 8 and g['down'] < 20, f'{name} glide: {seen}'
+        assert l['on_ground'] and not l['client'] and not l['server'], f'{name} landed: {seen}'
+    return seen
+
+
+CHECKS += ['elytra']
+CHECK_FNS.update(elytra=check_elytra)
+
+
+def server_using(host, game):
+    """The item the server has the player using ({slot, ticks}), or None."""
+    if game is host and not SERVER_THREAD:
+        return host('state').get('using')
+    return server_player(host, game).get('using')
+
+
+def flying(game, kind):
+    """How many of the projectiles this side draws are of `kind` (a trident, an arrow)."""
+    return sum(kind in q['kind'].lower() for q in game('status')['projectiles'])
+
+
+def check_held_use(host, guest, out):
+    """Items used until the button lets go, for each player: the client starts the use too
+    (Item.use runs on both sides), so letting go sends RELEASE_USE_ITEM and the server ends it."""
+    hx, hy, hz = (int(v // 1) for v in pos_of(host))
+    seen = {}
+    try:
+        for game, dz in ((host, -3), (guest, 3)):
+            x, z = hx, hz + dz
+            host('command', command=f'fill {x - 1} {hy - 1} {z - 1} {x + 12} {hy - 1} {z + 1} minecraft:stone')
+            host('command', command=f'fill {x - 1} {hy} {z - 1} {x + 12} {hy + 3} {z + 1} minecraft:air')
+            host('command', command=f'fill {x + 12} {hy} {z - 1} {x + 12} {hy + 3} {z + 1} minecraft:stone')
+            game('command', command='gamemode survival')
+            game('command', command='clear @s')
+            game('command', command=f'tp @s {x + 0.5} {hy} {z + 0.5} -90 0')
+            game.wait(10)
+            s = {}
+            # ShieldItem: raised while held, lowered once let go.
+            game('command', command='item replace entity @s weapon.offhand with minecraft:shield')
+            game.wait(5)
+            game.raw('mouse', 'right', 'down')
+            game.wait(10)
+            s['shield'] = {'held': (bool(game('state').get('using')), bool(server_using(host, game)))}
+            game.raw('mouse', 'right', 'up')
+            game.wait(10)
+            s['shield']['let_go'] = (bool(game('state').get('using')), bool(server_using(host, game)))
+            game('command', command='item replace entity @s weapon.offhand with minecraft:air')
+            # SpyglassItem: scoping while held.
+            game('command', command='item replace entity @s weapon.mainhand with minecraft:spyglass')
+            game.wait(5)
+            game.raw('mouse', 'right', 'down')
+            game.wait(10)
+            s['spyglass'] = {'held': (bool(game('state').get('using')), bool(server_using(host, game)))}
+            game.raw('mouse', 'right', 'up')
+            game.wait(10)
+            s['spyglass']['let_go'] = (bool(game('state').get('using')), bool(server_using(host, game)))
+            # TridentItem.releaseUsing after 10 ticks: thrown.
+            host('command', command='kill @e[type=minecraft:trident]')
+            game('command', command='item replace entity @s weapon.mainhand with minecraft:trident')
+            game.wait(5)
+            # /kill finds no thrown trident (Horizon's selectors miss them): count what's new.
+            before = flying(game, 'trident')
+            game.raw('use-item', '--hold', 1.2)
+            game.wait(10)
+            s['trident'] = {'kept': server_count(game, 'trident'),
+                            'thrown': flying(game, 'trident') - before}
+            host('command', command='kill @e[type=minecraft:trident]')
+            # CrossbowItem: charged by holding (25 ticks), fired by the next use.
+            host('command', command='kill @e[type=minecraft:arrow]')
+            game('command', command='clear @s')
+            game('command', command='item replace entity @s weapon.mainhand with minecraft:crossbow')
+            game('command', command='give @s minecraft:arrow 16')
+            game.wait(5)
+            before = flying(game, 'arrow')
+            game.raw('use-item', '--hold', 1.6)
+            game.wait(10)
+            held = game('state').get('held') or {}
+            s['crossbow'] = {'loaded': 'charged_projectiles' in str(held.get('components', '')),
+                             'arrows': server_count(game, 'arrow')}
+            game.raw('use-item')
+            game.wait(10)
+            held = game('state').get('held') or {}
+            s['crossbow'].update(
+                fired=flying(game, 'arrow') - before,
+                emptied='charged_projectiles' not in str(held.get('components', '')))
+            game.shot(out, 'helduse')
+            seen[game.name] = s
+    finally:
+        host('command', command='kill @e[type=minecraft:arrow]')
+        host('command', command='kill @e[type=minecraft:trident]')
+        for game in (host, guest):
+            back_to_game(game)
+            game.raw('mouse', 'right', 'up')
+            game('command', command='clear @s')
+        face_each_other(host, guest)
+    for name, s in seen.items():
+        for item in ('shield', 'spyglass'):
+            assert s[item] == {'held': (True, True), 'let_go': (False, False)}, f'{name} {item}: {seen}'
+        assert s['trident'] == {'kept': 0, 'thrown': 1}, f'{name} trident: {seen}'
+        assert s['crossbow'] == {'loaded': True, 'arrows': 15, 'fired': 1, 'emptied': True}, \
+            f'{name} crossbow: {seen}'
+    return seen
+
+
+CHECKS += ['helduse']
+CHECK_FNS.update(helduse=check_held_use)
+
+
+def check_wind(host, guest, out):
+    """A wind charge each player throws at its own feet (ServerExplosion with TRIGGER_BLOCK): the
+    server's burst pushes the thrower through its ClientboundExplodePacket (hitPlayers), which
+    launches it about six blocks up, and onExplosionHit spares it the fall damage where it lands
+    (#1386)."""
+    hx, hy, hz = (int(v // 1) for v in pos_of(host))
+    host('command', command='gamerule natural_health_regeneration false')
+    seen = {}
+    try:
+        for game, dz in ((host, -4), (guest, 4)):
+            x, z = hx, hz + dz
+            host('command', command=f'fill {x - 2} {hy - 1} {z - 2} {x + 2} {hy - 1} {z + 2} minecraft:stone')
+            host('command', command=f'fill {x - 2} {hy} {z - 2} {x + 2} {hy + 10} {z + 2} minecraft:air')
+            game('command', command='gamemode survival')
+            game('command', command='clear @s')
+            game('command', command='effect clear @s')
+            game('command', command='effect give @s minecraft:instant_health 1 5 true')
+            game('command', command='give @s minecraft:wind_charge 2')
+            game('command', command=f'tp @s {x + 0.5} {hy} {z + 0.5} 0 90')
+            game.wait(20)
+            start = pos_of(game)[1]
+            game.raw('use-item')
+            peak = start
+            for _ in range(30):
+                game.wait(2)
+                peak = max(peak, pos_of(game)[1])
+            game.wait(40)
+            game.shot(out, 'wind')
+            me = own(game)
+            seen[game.name] = {'rose': round(peak - start, 1),
+                               'landed': round(me['position'][1] - start, 1),
+                               'health': me['health'],
+                               'server_health': server_player(host, game)['health'],
+                               'charges': server_count(game, 'wind_charge')}
+    finally:
+        host('command', command='gamerule natural_health_regeneration true')
+        for game in (host, guest):
+            game('command', command='clear @s')
+        face_each_other(host, guest)
+    for name, s in seen.items():
+        # Vanilla rises about 6 blocks from a charge at the feet.
+        assert 4 < s['rose'] < 8 and s['landed'] == 0, f'{name}: {seen}'
+        assert s['health'] == 20 and s['server_health'] == 20 and s['charges'] == 1, f'{name}: {seen}'
+    return seen
+
+
+CHECKS += ['wind']
+CHECK_FNS.update(wind=check_wind)
 
 
 if __name__ == '__main__':