Union union/pt2-c2: #2570 461a8757e

An empty `biome_is` list on a surface that does not number its biomes
compiled to the id comparison, since collecting no indices never asks
`biome_index`. It then failed with MissingBiomeProvider where vanilla and
main answer false (material_condition's codec-corpus condition 49). It
keeps the name lookup main uses. Review on #3366.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

.claude/skills/vanilla-parity/SKILL.md

@@ -0,0 +1,76 @@
+---
+name: vanilla-parity
+description: Fix a Horizon bug or gap so it behaves 1:1 like vanilla 26.3, starting from the port ledger (tools/port_ledger.py) instead of grepping. Use for any issue, Discord report or PR that makes Horizon match vanilla: "X doesn't work like in Java", a missing sound, particle, animation, mob behaviour, block rule, screen or packet.
+---
+
+# Vanilla parity with the port ledger
+
+The port ledger pairs every vanilla method with the Rust fn that ports it (or says it is missing, or needs
+no port) and lists where a port isn't wired like vanilla. Ask it first; grep only for what it can't answer.
+Full reference: `docs/port-ledger.md`.
+
+## 0. Have a fresh ledger
+
+```sh
+python3 tools/port_ledger.py build          # ~20 s; again after pulling main
+```
+
+It needs the vanilla jar (the launcher's `versions/26.3/26.3.jar`, or `--jar`) and/or the lab's decompiled
+sources (`python3 tools/lab.py decompile`, or `--sources DIR`). If `build` says it has no vanilla code, run
+the lab first; don't guess vanilla from memory.
+
+## 1. From the report to the code
+
+```sh
+python3 tools/port_ledger.py issue 3236                      # a GitHub issue number
+python3 tools/port_ledger.py issue "mooshroom stays red after lightning"   # or the report's text
+```
+
+It ranks the vanilla classes the report names and lists, per class, its Rust home files, where each method is
+ported, and the known gaps (`missing` rows from the verdict map, seam/client/drift gaps). Often the cause is
+already written there ("Type is not saved"). Then drill in:
+
+```sh
+python3 tools/port_ledger.py where MushroomCow.readAdditionalSaveData   # ports, callers, callees, gaps
+python3 tools/port_ledger.py class MushroomCow                          # every method: where, or missing
+python3 tools/port_ledger.py what crates/horizon-client/src/mobs/farm.rs:120   # which vanilla method a fn ports
+```
+
+A ledger answer is a lead, not a verdict: about 1 in 12 map rows is wrong. Read the vanilla method (path and
+line are in the output) and the Rust fn before changing anything.
+
+## 2. Port it the vanilla way
+
+- Translate the vanilla method, don't reinvent it: same order of operations, same constants, the same random
+  draws in the same order (`horizon_core::random`), Java `Math` through `horizon_core::jmath`.
+- Open the fn's doc with the vanilla method it ports: `` /// `MushroomCow.readAdditionalSaveData`: ... ``.
+  That one line is what makes the next agent find it.
+- Fix the path players run: single player is a client of the integrated server, so server logic lives in
+  `game/lan*.rs` and `src/lan/`, and what only the client's copy shows (particles, local sounds, hand
+  animation) must be reached from `game/remote*.rs`. A fix on the old in-frame path alone fixes nothing.
+- Look at the neighbours the ledger lists for the same class: a `client` or `seam` gap next to your fix is
+  usually the same bug on the other path.
+
+## 3. Before the PR
+
+```sh
+python3 tools/port_ledger.py check --base origin/main
+```
+
+It lists the ports your branch touches with their open gaps, citations to add, stale citations, and (against
+the base) the gaps the branch closes and opens. Close what belongs to your fix, cite what you ported, leave
+no new stale citation. If you ported a method the verdict map called `missing`, change its row in
+`tools/port_map/*.tsv` to `port` with the fn (`file.rs::Owner::fn`) and run
+`python3 tools/port_ledger.py map-check tools/port_map/<file>.tsv`.
+
+Then the usual: the harness for the area (`docs/architecture.md`), `cargo check`/tests per `AGENTS.md`, and
+a small PR that says which vanilla method it now matches.
+
+## Finding work
+
+```sh
+python3 tools/port_ledger.py gaps --kind seam      # ported on two paths, wired on one: the best leads
+python3 tools/port_ledger.py gaps --kind client    # client-only effects the server path never reaches
+python3 tools/port_ledger.py gaps --kind drift     # a port missing a sound, particle, item or constant
+rg -n "player:" tools/port_map/*.tsv               # missing behaviour a player would see
+```

.github/workflows/cancel-on-close.yml

@@ -16,12 +16,14 @@ jobs:
           GH_TOKEN: ${{ github.token }}
           REPO: ${{ github.repository }}
           BRANCH: ${{ github.event.pull_request.head.ref }}
-          SHA: ${{ github.event.pull_request.head.sha }}
+          HEAD_REPO: ${{ github.event.pull_request.head.repo.full_name }}
         run: |
+          # Every head the pull request had, not only its last: a run-parity label added on an older head left that
+          # run queued after the merge (#3104, 2026-10-29). Its branch in its own repository names its runs (another
+          # fork can have a branch of the same name).
           for status in queued in_progress waiting pending requested; do
-            gh run list -R "$REPO" --branch "$BRANCH" --status "$status" --limit 100 \
-              --json databaseId,event,headSha \
-              -q ".[] | select(.event == \"pull_request\" and .headSha == \"$SHA\") | .databaseId"
+            gh api -X GET "repos/$REPO/actions/runs" -f branch="$BRANCH" -f event=pull_request -f status="$status" \
+              -f per_page=100 --jq ".workflow_runs[] | select(.head_repository.full_name == \"$HEAD_REPO\") | .id"
           done | sort -u | while read -r id; do
             gh run cancel -R "$REPO" "$id" || true
           done

.github/workflows/game-build.yml

@@ -37,9 +37,10 @@ permissions:
 jobs:
   exporters:
     # This runner holds the maintainer's own pinned Minecraft jars. Only our classes leave it. An untrusted build
-    # goes to the Mac mini runner that already runs pull requests' parity jobs (macOS + horizon-game:
-    # ludovics-mac-mini), never the release runner (MAC_RUNNER: ludovics-mac-mini-release) nor parity-main's.
-    runs-on: ${{ inputs.trusted && vars.MAC_RUNNER || fromJSON('["self-hosted", "macOS", "horizon-game"]') }}
+    # goes to the Mac mini's nightly runner (macOS + horizon-nightly: ludovics-mac-mini-nightly, beside the one that
+    # runs pull requests' parity jobs, so a nightly never waits behind their queue), never the release runner
+    # (MAC_RUNNER: ludovics-mac-mini-release) nor parity-main's.
+    runs-on: ${{ inputs.trusted && vars.MAC_RUNNER || fromJSON('["self-hosted", "macOS", "horizon-nightly"]') }}
     # Three full preparations (two isolated, one batched) besides the compile.
     timeout-minutes: 60
     steps:
@@ -103,7 +104,7 @@ jobs:
             mac: true
             dir: horizon-macos-arm64
             asset: horizon-macos-arm64.zip
-    runs-on: ${{ matrix.mac && (inputs.trusted && vars.MAC_RUNNER || fromJSON('["self-hosted", "macOS", "horizon-game"]')) || matrix.os }}
+    runs-on: ${{ matrix.mac && (inputs.trusted && vars.MAC_RUNNER || fromJSON('["self-hosted", "macOS", "horizon-nightly"]')) || matrix.os }}
     # Notarizing the zip can take a few minutes.
     timeout-minutes: ${{ matrix.mac && 60 || 40 }}
     env:

.github/workflows/run-parity.yml

@@ -5,11 +5,15 @@ name: run-parity
 # skipped `verify`, and GitHub counts a skipped required check as passed.
 on:
   pull_request:
-    types: [labeled]
+    # A push starts a run only to cancel the old head's (see concurrency): the job runs on the label alone.
+    types: [labeled, synchronize]
 permissions:
   contents: read
 concurrency:
-  group: run-parity-${{ github.event.pull_request.number }}
+  # The run-parity label and pushes share one group per pull request, so the newest run cancels the one before: a
+  # pushed pull request's run tested a head the merge would no longer land. Any other label gets a group of its own:
+  # in the shared one, adding needs-proof cancelled the parity run queued seconds before (run 40766180150).
+  group: run-parity-${{ github.event.pull_request.number }}${{ github.event.action == 'labeled' && github.event.label.name != 'run-parity' && format('-{0}', github.run_id) || '' }}
   cancel-in-progress: true
 env:
   # Test runs never reach the telemetry server: no live-count ping, no uploads (docs/telemetry.md).

AGENTS.md

@@ -35,11 +35,12 @@ Game workspace (root `Cargo.toml`); `launcher/` and `crates/horizon-telemetry-se
 
 | Crate | Owns |
 |---|---|
-| `horizon-client` | The game: a lib (`src/lib.rs`, ~170 flat modules) and the bin (`src/main.rs` → `game.rs` + `game/`), plus `horizon-ctl` (`src/bin/horizon-ctl/`). Also the dedicated server (`--dedicated`) |
+| `horizon-client` | The game: a lib (`src/lib.rs`, ~100 flat modules: gameplay, networking, title screens) and the bin (`src/main.rs` → `game.rs` + `game/`), plus `horizon-ctl` (`src/bin/horizon-ctl/`). Also the dedicated server (`--dedicated`) |
 | `horizon-items` | Blocks and items below gameplay: `blocks.rs` (block facts), `items.rs`, `item_data.rs` (components), `enchant.rs`, `cooldowns.rs`, `bundle.rs`, `item_nbt.rs`. Re-exported as `horizon_client::items`... |
 | `horizon-command` | Command parsing (Brigadier): the vanilla tree, argument types, selectors, suggestions, the tree's network form. Re-exported as `horizon_client::command` |
 | `horizon-client-core` | The client lib's bottom layer: `text.rs`, `lang.rs`, `snbt.rs`, `nbt_path.rs`, `component.rs`, `scoreboard.rs`, `bossbar.rs`, `gamerules.rs`, `block_entity_nbt.rs`, registry/particle/sound tables. Re-exported under the old paths (`horizon_client::text`...) |
 | `horizon-client-input` | Key bindings and key names, toggle keys, mouse options, controller settings and glyphs, the clipboard, window options (`keybinds.rs`, `gamepad.rs`, `mouse.rs`, `window.rs`...). Re-exported under the old paths |
+| `horizon-client-render` | The client's world data, rendering and screens (chunks, meshing, light, streaming, `gfx`, HUD, menus, settings): ~80 modules that horizon-client re-exports under the same paths. Nothing in it reaches gameplay |
 | `horizon-world` | Vanilla world data with no gameplay loop: NBT, regions, chunks, `datafix/`, `worldgen/`, `level/` (server-side block behaviour, ticks, redstone), entity physics, items, effects, food, damage |
 | `horizon-core` | Simulation primitives: Java `Random`s, `jmath` (HotSpot-exact `Math`), positions, noise, density, paletted storage, `version.rs` (the pinned version) |
 | `horizon-protocol` | Network protocol 777: codecs, framing, encryption, `packets/{handshake,status,login,configuration,play}.rs`, `entity_data.rs` |
@@ -99,6 +100,9 @@ python3 tools/agent_control_e2e.py         # horizon-ctl / MCP end to end
 
 ## Vanilla reference
 
+- Start parity work from the port ledger, not grep: `python3 tools/port_ledger.py issue N` (or `where
+  Class.method`, `what file:line`), and `check --base origin/main` before the PR. How:
+  [.claude/skills/vanilla-parity/SKILL.md](.claude/skills/vanilla-parity/SKILL.md), [docs/port-ledger.md](docs/port-ledger.md).
 - Decompiled sources: `.local/minecraft/26.3/sources/{client,server}/` (`python3 tools/lab.py decompile`).
 - Bytecode queries (callers through lambdas, every overload):
   `python3 tools/rea_vanilla.py method net.minecraft.world.level.block.DispenserBlock dispenseFrom`
@@ -110,7 +114,8 @@ python3 tools/agent_control_e2e.py         # horizon-ctl / MCP end to end
 
 ## horizon-client: where things live
 
-`L:` = lib (`crates/horizon-client/src/`), `G:` = bin (`crates/horizon-client/src/game/`). The lib can't see
+`L:` = lib (`crates/horizon-client/src/`, or `crates/horizon-client-render/src/` for the modules that crate holds, under
+the same `horizon_client::<module>` paths), `G:` = bin (`crates/horizon-client/src/game/`). The lib can't see
 `Game`; bin code reaches the lib as `horizon_client::<module>`.
 
 | Subsystem | Files |

Cargo.lock

@@ -1378,7 +1378,6 @@ dependencies = [
  "ab_glyph",
  "bytemuck",
  "chrono",
- "cpal",
  "flate2",
  "gilrs",
  "glam",
@@ -1386,6 +1385,7 @@ dependencies = [
  "horizon-bench",
  "horizon-client-core",
  "horizon-client-input",
+ "horizon-client-render",
  "horizon-command",
  "horizon-core",
  "horizon-dualsense",
@@ -1412,7 +1412,6 @@ dependencies = [
  "serde_json",
  "sha1",
  "sha2",
- "symphonia",
  "unicode-bidi",
  "ureq",
  "wgpu",
@@ -1441,6 +1440,48 @@ dependencies = [
  "winit",
 ]
 
+[[package]]
+name = "horizon-client-render"
+version = "0.1.0"
+dependencies = [
+ "ab_glyph",
+ "bytemuck",
+ "chrono",
+ "cpal",
+ "flate2",
+ "glam",
+ "horizon-assets",
+ "horizon-bench",
+ "horizon-client-core",
+ "horizon-client-input",
+ "horizon-command",
+ "horizon-core",
+ "horizon-hdr",
+ "horizon-items",
+ "horizon-protocol",
+ "horizon-shader-api",
+ "horizon-shaders",
+ "horizon-telemetry",
+ "horizon-theme",
+ "horizon-threads",
+ "horizon-world",
+ "log",
+ "miniz_oxide 0.8.9",
+ "naga",
+ "png",
+ "pollster",
+ "rustix 1.1.5",
+ "serde",
+ "serde_json",
+ "sha2",
+ "symphonia",
+ "unicode-bidi",
+ "ureq",
+ "wgpu",
+ "winit",
+ "zip",
+]
+
 [[package]]
 name = "horizon-command"
 version = "0.1.0"

Cargo.toml

@@ -9,6 +9,7 @@ members = [
     "crates/horizon-client",
     "crates/horizon-client-core",
     "crates/horizon-client-input",
+    "crates/horizon-client-render",
     "crates/horizon-command",
     "crates/horizon-items",
     "crates/horizon-server-files",

README.md

@@ -1,5 +1,5 @@
 <p align="center">
-  <img src="docs/media/banner.webp" alt="Horizon: Minecraft: Java Edition 26.3, rewritten in Rust and checked against vanilla by 281 differential harnesses" width="100%">
+  <img src="docs/media/banner.webp" alt="Horizon: Minecraft: Java Edition 26.3, rewritten in Rust and checked against vanilla by more than 300 differential harnesses" width="100%">
 </p>
 
 <p align="center">
@@ -23,15 +23,15 @@
 
 # Horizon
 
-Horizon is Minecraft: Java Edition 26.3 rewritten in Rust: a native game that reads the same worlds, follows the same rules and generates the same terrain as the Java game, and is checked against it by 281 differential harnesses. You play it through a small launcher, on the files from your own copy of Minecraft. It is free, open source and unofficial.
+Horizon is Minecraft: Java Edition 26.3 rewritten in Rust: a native game that reads the same worlds, follows the same rules and generates the same terrain as the Java game, and is checked against it by more than 300 differential harnesses. You play it through a small launcher, on the files from your own copy of Minecraft. It is free, open source and unofficial.
 
 > Not an official Minecraft product. Not approved by or associated with Mojang or Microsoft. Horizon contains no Minecraft code, assets or data: you need your own legally obtained copy of Minecraft: Java Edition 26.3.
 
 ## Download
 
-Horizon is installed through **the Horizon launcher**. Get it from [playhorizon.dev](https://playhorizon.dev) (the Download button picks your system) or from [the launcher releases](https://github.com/horizon-rust/horizon/releases?q=launcher-v&expanded=true), for Linux x86-64, macOS on Apple Silicon or Windows x64. The launcher installs and updates the game, prepares its files from your copy of Minecraft (your own install, or downloaded from Mojang for your account), and updates itself.
+Horizon is installed through **the Horizon launcher**. Get it from [playhorizon.dev](https://playhorizon.dev) (the Download button picks your system) or from [the launcher releases](https://github.com/horizon-rust/horizon/releases?q=launcher-v&expanded=true), for Linux x86-64, macOS on Apple Silicon or Windows x64. The launcher installs the game and keeps it up to date with each new build (Horizon ships on one channel, the Nightly), prepares its files from your copy of Minecraft (your own install, or downloaded from Mojang for your account), and updates itself.
 
-**You need** a Microsoft account that owns Minecraft: Java Edition (the launcher signs in with it, as other launchers do; see [Microsoft account](docs/microsoft-account.md)) and a GPU with Vulkan on Linux and Windows, or any Apple Silicon Mac. Nothing else: with no Minecraft on your computer, Play downloads 26.3 and the Java it needs from Mojang for your account, as the official launcher does, then prepares it once. An install you already have (the official launcher, Prism, MultiMC and other launchers all work) is used instead. Step by step, with macOS's first-open prompt and the first launch: [Install and first launch](https://playhorizon.dev/docs/install).
+**You need** a Microsoft account that owns Minecraft: Java Edition (the launcher signs in with it, as other launchers do; see [Microsoft account](docs/microsoft-account.md)) and a GPU with Vulkan or OpenGL 3.3 on Linux, Vulkan or DirectX 12 on Windows, or any Apple Silicon Mac. Nothing else: with no Minecraft on your computer, Play downloads 26.3 and the Java it needs from Mojang for your account, as the official launcher does, then prepares it once. An install you already have (the official launcher, Prism, MultiMC and other launchers all work) is used instead. Step by step, with macOS's first-open prompt and the first launch: [Install and first launch](https://playhorizon.dev/docs/install).
 
 <table>
   <tr>
@@ -46,9 +46,9 @@ The [documentation](https://playhorizon.dev/docs/) covers each of these.
 
 - **The game:** singleplayer with vanilla's world generation, mobs, villagers, raids, redstone, every command, the HUD and the recipe book, on saves in vanilla's format. Worlds from 1.8 to 26.2 are upgraded as vanilla does. [Status table](#project-status).
 - **Horizon's own extras:** new menus (vanilla's are one setting away), graphics presets, distant terrain up to 1024 chunks, controller support, optional zoom, minimap and more, all off by default where they would change the vanilla look. See [Settings](https://playhorizon.dev/docs/settings).
-- **Resource packs and data packs:** resource packs work, and data packs load functions, predicates and item modifiers.
+- **Resource packs and data packs:** resource packs work, and data packs load functions, predicates, item modifiers and world generation (vanilla's heights and biomes for now).
 - **Playing with others:** invite friends from the pause menu's Friends button with a code, Open to LAN, and joining servers, online-mode ones with the Microsoft account the launcher signs in with. See [Multiplayer](https://playhorizon.dev/docs/multiplayer).
-- **Mods:** Horizon has its own mod system (Rust compiled to WebAssembly). Java mod jars do not run. See [Mods and data packs](https://playhorizon.dev/docs/mods).
+- **Mods:** Horizon has its own mods, installed from the launcher. The official ones (Zoom, FPS Counter, Keystrokes and Minimap) are native Rust that the launcher builds into your game, with no Rust to install; older WebAssembly mods still run while they move. Java mod jars do not run in Horizon. See [Mods and data packs](https://playhorizon.dev/docs/mods).
 
 Screenshots, captured in the Rust client itself with vanilla assets and no mods or shaders:
 
@@ -139,6 +139,11 @@ average; `tests/test_parity.py` keeps it in sync with this table. Last audited
 rerun whenever one of its inputs changed, and the Mac mini now runs every one of
 them too (Rust uses Java's own float maths on each platform).
 
+The harnesses measure behaviour. A second measure is method by method: the [port ledger](tools/port_ledger.py)
+lists every method of vanilla 26.3 next to the Rust functions that port it, with a verdict for each one
+(ported, folded into another function, missing, or needing no port), and the untested ports. Run
+`python3 tools/port_ledger.py build`, then `coverage`, with the vanilla data in `.local/`.
+
 | Subsystem | Score | Main gaps |
 | --- | ---: | --- |
 | Window, input and game loop | 1 | None: the game loop, options, camera, auto-jump, toggle sprint/sneak, local input and the frame limiter match vanilla |

ROADMAP.md

@@ -16,7 +16,7 @@ Horizon is Minecraft: Java Edition 26.3 rewritten from scratch in Rust, so it ru
 - **Single player as a server: the last differences**: Single player now runs a small server in the background, as vanilla does. We are fixing what still behaves differently there; every fix also works for LAN and server players.
 - **Horizon's mod registry**: One place for mods, modpacks and resource packs made for Horizon: browse them on the website and install them from the launcher in one click.
 
-**Next**: Microsoft sign-in (coming soon); CurseForge in the mod browser (coming soon); Fresh benchmarks against vanilla; Pistons push players and mobs; Horizon on Intel Macs; Faster world creation and entry on small CPUs; Servers that hold 20 TPS with 50 to 100 players; Low-end computers: Steam Deck, old Macs, 8 GB; Native upscaling; A batch of targeted optimisations; A Convert to Rust button for what isn't rewritten yet; Mods with code: machines, magic, mobs; Data packs in the mod browser; Prepare a version without Java; Server console, bans and a full admin API; Hosting polish: Windows service, safe updates; Guided hosting with Tailscale and an invite button; An official Docker image for servers; One single-player path: remove the in-frame world; Villages and combat, exactly as in vanilla; Choose the audio output device; Mods that read and change the world; Machines and blocks with inventories (API 0.4); Lua and other languages for mods; Well-known shader looks, rewritten for Horizon; A visible beta label; Wayland and Hyprland polish; A versioned agent-control protocol; Port mods with your own AI agent; Horizon on X (coming soon); Pipeline protection and a GitHub App for agents; Signed updates everywhere, installers included; A server you install with one command.
+**Next**: A new launcher design; CurseForge in the mod browser (coming soon); Fresh benchmarks against vanilla; Pistons push players and mobs; Horizon on Intel Macs; Faster world creation and entry on small CPUs; Servers that hold 20 TPS with 50 to 100 players; Low-end computers: Steam Deck, old Macs, 8 GB; Native upscaling; A batch of targeted optimisations; A Convert to Rust button for what isn't rewritten yet; Mods with code: machines, magic, mobs; Data packs in the mod browser; Prepare a version without Java; Server console, bans and a full admin API; Hosting polish: Windows service, safe updates; Guided hosting with Tailscale and an invite button; An official Docker image for servers; One single-player path: remove the in-frame world; Villages and combat, exactly as in vanilla; Choose the audio output device; Mods that read and change the world; Machines and blocks with inventories (API 0.4); Well-known shader looks, rewritten for Horizon; A visible beta label; Wayland and Hyprland polish; A versioned agent-control protocol; Port mods with your own AI agent; Horizon on X (coming soon); Pipeline protection and a GitHub App for agents; Signed updates everywhere, installers included; A server you install with one command; Ready-made setups for hosting panels.
 
 **How to help**: Play it and tell us what differs from vanilla (Discord or GitHub), run the benchmark on your computer, vote for what you want next, or pick one of the Help wanted items.
 
@@ -104,37 +104,49 @@ More: [docs/mods.md](docs/mods.md)
 
 </details>
 
+#### Native mods, built by the launcher
+
+Horizon's own mods become native code that the launcher builds into your game, with no Rust to install: Zoom, FPS Counter, Keystrokes and Minimap already are, and Recipes is next.
+
+<details><summary>Technical</summary>
+
+Stable hook points in the game (game/native_hooks.rs, [#3345](https://github.com/horizon-rust/horizon/issues/3345), [#3346](https://github.com/horizon-rust/horizon/issues/3346); v2 with the item panel and recipe pages, [#3434](https://github.com/horizon-rust/horizon/issues/3434), [#3435](https://github.com/horizon-rust/horizon/issues/3435)), horizon-mixins applied by the launcher with its own portable Rust ([#3388](https://github.com/horizon-rust/horizon/issues/3388)), on/off in Options > Mods. The official mods live in horizon-mods/native/ and are in the registry as native mods. Next: Recipes, native mods on automatically when a player installs one (with a notice about the first build), then the WebAssembly runtime is removed ([#3350](https://github.com/horizon-rust/horizon/issues/3350), [#3351](https://github.com/horizon-rust/horizon/issues/3351), [#3353](https://github.com/horizon-rust/horizon/issues/3353), [#3371](https://github.com/horizon-rust/horizon/issues/3371)).
+
+More: [docs/native-mods.md](docs/native-mods.md)
+
+</details>
+
 #### Mods that run on the server
 
 Mods that run on the server side of a world, so a dedicated server or a LAN world can have mods that react to players joining, chat and blocks being broken or placed, and that add commands.
 
 <details><summary>Technical</summary>
 
-API 0.3, experimental first ([#1833](https://github.com/horizon-rust/horizon/issues/1833), in review): the same sandboxed component runs on the server thread and the dedicated server, with world events (block broken or placed, entity spawned or killed, player joined or left), game rules and server commands with typed arguments. The world, item and entity interfaces come after (see 'Mods that read and change the world'). [docs/api/mods.md](docs/api/mods.md), [docs/mods.md](docs/mods.md).
+The same hook points on the server thread and the dedicated server: world events (block broken or placed, entity spawned or killed, player joined or left), game rules and server commands with typed arguments. The earlier WebAssembly API 0.3 ([#1833](https://github.com/horizon-rust/horizon/issues/1833)) is the reference for what to cover.
+
+More: [docs/native-mods.md](docs/native-mods.md)
 
 </details>
 
 #### Screens, input and drawing for mods
 
-Mods will be able to open their own screens and settings pages and react to keys and item use, so bigger mods, such as the Orbital Laser, can run on the normal game.
+Mods will be able to open their own screens and settings pages, react to keys and item use, and draw, so bigger mods, such as the Orbital Laser, run on the normal game.
 
 <details><summary>Technical</summary>
 
-Capability `ui` is in review ([#1864](https://github.com/horizon-rust/horizon/issues/1864)): mod-owned screens and a settings page under Options > Mods, built from vanilla's widgets. Still to design: `input` (an item's use, key binds, the crosshair target), `render` (a budgeted draw list on the native shader API) and `world` (changing blocks). Orbital Laser is the acceptance test: it needs all four today through its author's fork (see 'Orbital Laser on the normal game').
-
-More: [docs/mods.md](docs/mods.md)
+On native hook points ([docs/native-mods.md](docs/native-mods.md)): settings pages under Options > Mods and the item panel are there ([#3346](https://github.com/horizon-rust/horizon/issues/3346), [#3435](https://github.com/horizon-rust/horizon/issues/3435)). Next: mod-owned screens built from vanilla's widgets, an item's use, key binds and the crosshair target, and a budgeted draw list on the native shader API. Orbital Laser is the acceptance test.
 
 </details>
 
 #### Tools for people who make mods
 
-Better tools for mod makers: a test runner that needs no game window, templates for each kind of mod, and clear promises about what keeps working from one version to the next.
+Better tools for mod makers: templates for each kind of mod, a test run with no game window, and clear promises about which hook points keep working from one version to the next.
 
 <details><summary>Technical</summary>
 
-`cargo horizon-mod test` runs a mod's test scripts against a fake game snapshot ([#1816](https://github.com/horizon-rust/horizon/issues/1816)) and, for server mods, scripted server events ([#1837](https://github.com/horizon-rust/horizon/issues/1837)); the content template and the guides are merged ([#1859](https://github.com/horizon-rust/horizon/issues/1859), [#1810](https://github.com/horizon-rust/horizon/issues/1810), [docs/api/stability.md](docs/api/stability.md)). Left: templates for hud, server and machine mods, typed wrappers in the SDK, a frozen 0.1 compatibility mod that every runtime must load, a CI check that fails when a stable reference entry is removed without a new major version, and the SDK on crates.io once the API is stable.
+Native mod template and the content mod template (horizon-mods), `native.py check` that applies mods on a chosen Horizon and builds them together, a weekly check of every official mod on the newest Nightly. Left: a versioned list of stable hook points (NATIVE_HOOKS_API), a test runner without a window, and docs on the site for native mods.
 
-More: [https://playhorizon.dev/docs/test-a-mod](https://playhorizon.dev/docs/test-a-mod)
+More: [#3388](https://github.com/horizon-rust/horizon/issues/3388) · [docs/native-mods.md](docs/native-mods.md)
 
 </details>
 
@@ -244,6 +256,20 @@ Horizon's own way to make shader packs, with tools to write and test them. Every
 
 </details>
 
+### Launcher
+
+#### Minecraft Java instances in the launcher
+
+Play the real Java game from the Horizon launcher too: vanilla and modded instances, any version, mods from Modrinth filtered to what fits, and your instances imported from other launchers.
+
+<details><summary>Technical</summary>
+
+For an account that owns the game: any version downloaded with the Java it needs ([#3406](https://github.com/horizon-rust/horizon/issues/3406)), Java instances, the version list and the CLI ([#3395](https://github.com/horizon-rust/horizon/issues/3395)), the start command read from the version JSON ([#3419](https://github.com/horizon-rust/horizon/issues/3419)). Next: Play for a Java instance, Fabric and Quilt, then NeoForge and Forge; Modrinth with compatibility filtering and dependencies; imports from Prism, MultiMC, the CurseForge app, the Modrinth App, ATLauncher and the official launcher, each from its documented on-disk format.
+
+More: [#3506](https://github.com/horizon-rust/horizon/issues/3506)
+
+</details>
+
 ### Horizon extras
 
 #### Discord Rich Presence
@@ -268,6 +294,16 @@ A review of the whole tree: dead code and stubs removed ([#1432](https://github.
 
 </details>
 
+#### Every vanilla method, tracked
+
+A public list of every method of the Java game and where Horizon does it, so anyone can see what is ported, what is missing and pick something to fix.
+
+<details><summary>Technical</summary>
+
+[tools/port_ledger.py](tools/port_ledger.py) and tools/port_map/ ([#3139](https://github.com/horizon-rust/horizon/issues/3139)): every 26.3 method outside the skipped packages has a verdict (port, inline, missing, skip, trivial), linked to the harnesses that cover it ([#3526](https://github.com/horizon-rust/horizon/issues/3526)), with one tracking issue per area. Bug fixes start from it (.claude/skills/vanilla-parity).
+
+</details>
+
 ## Next
 
 ### Performance
@@ -444,6 +480,16 @@ A player's idea (#horizon-ideas). `horizon-server` already runs headless; left:
 
 </details>
 
+#### Ready-made setups for hosting panels
+
+Install a Horizon server from the panels hosts use, such as Pterodactyl and AMP, the usual way for each panel.
+
+<details><summary>Technical</summary>
+
+Asked in the suggestion queue for Pterodactyl eggs and AMP templates. Builds on the one-command install ('A server you install with one command') and horizon-server's server.toml ([docs/hosting.md](docs/hosting.md)).
+
+</details>
+
 ### Mods and API
 
 #### Mods that read and change the world
@@ -452,9 +498,9 @@ Mods that can see and change blocks, read inventories and items, and find and af
 
 <details><summary>Technical</summary>
 
-After server mods: read blocks, states and biomes in loaded chunks and change them through the server's block log, so clients and the parity harnesses see vanilla's updates; the player's inventory, held item, open container and item stacks with components; entity queries near a position, a safe subset of entity data and data-driven mod entity types. Snapshots and batched calls per tick, never per-block host calls in hot paths. [docs/api/mods.md](docs/api/mods.md) ('Not there yet').
+Hook points for reading blocks, states and biomes and changing them through the server's block log, so clients and the parity harnesses see vanilla's updates; the player's inventory and item stacks with components; entity queries near a position. Batched per tick, never per-block calls in hot paths.
 
-More: [docs/modpacks.md](docs/modpacks.md)
+More: [docs/native-mods.md](docs/native-mods.md) · [docs/modpacks.md](docs/modpacks.md)
 
 </details>
 
@@ -468,16 +514,6 @@ Block entities and menus: ticking machines with slots, server menu logic and the
 
 </details>
 
-#### Lua and other languages for mods
-
-Write mods as Lua scripts, in the style of KubeJS, with no compiler, and later in other languages that pass the tests. Every language runs in the same sandbox.
-
-<details><summary>Technical</summary>
-
-Lua first: Horizon ships a Lua interpreter that is itself a WebAssembly mod, and a script mod's manifest names it and the capabilities it uses, so a script can do exactly what a compiled mod with the same manifest can, with hot reload of `main.lua`. Then C, C++, Zig, Go (TinyGo), AssemblyScript and JavaScript or TypeScript are measured against Rust on the same tick-heavy example, and each is supported only with a template, an example and a CI test. [docs/api/mods.md](docs/api/mods.md) ('Ways in').
-
-</details>
-
 ### Gameplay parity
 
 #### Pistons push players and mobs
@@ -536,15 +572,13 @@ More: [docs/shaders.md](docs/shaders.md)
 
 ### Launcher
 
-#### Microsoft sign-in (coming soon)
+#### A new launcher design
 
-Coming soon: sign in with your Microsoft account to play on online-mode servers. The code is ready; it waits for Microsoft's approval.
+A redesigned launcher: every button where you expect it, the fewest clicks to play, add an instance or add mods, smooth animations, and instant startup.
 
 <details><summary>Technical</summary>
 
-Device-code sign-in in the launcher and online-mode login in the client ([docs/microsoft-account.md](docs/microsoft-account.md)). It is turned on by setting the app's client id once Minecraft API access is approved; until then the launcher shows "Coming soon".
-
-More: [#1270](https://github.com/horizon-rust/horizon/issues/1270)
+Based on the site concept by the Team (Bricolage Grotesque, a night sky and an animated pixel sunset). Screens and flows are designed first, then small PRs; tokens in [crates/horizon-theme](crates/horizon-theme) and rules in [docs/design-system.md](docs/design-system.md), the game's vanilla look unchanged. Measured before and after: startup, frame time and idle CPU/GPU, reduced motion honoured. Mods screens separate Horizon native mods from Java mods; a running instance can be stopped from the launcher.
 
 </details>
 
@@ -708,6 +742,18 @@ Issue [#1270](https://github.com/horizon-rust/horizon/issues/1270) asks for Ely.
 
 </details>
 
+#### Join servers on older versions
+
+Join servers that run older Minecraft versions, such as 1.21 or 1.8 PvP servers, from Horizon.
+
+<details><summary>Technical</summary>
+
+Asked often in the suggestion queue. Horizon speaks 26.3's protocol; the path is a native protocol adapter in Rust that translates older versions' packets, not a downloaded Java proxy. Java instances in the launcher already play any version with the real game.
+
+More: [#3023](https://github.com/horizon-rust/horizon/issues/3023)
+
+</details>
+
 #### Online-mode checks for Play with Friends
 
 Friends who join through an invite code could prove who they are with their Microsoft account, as on online-mode servers.
@@ -720,6 +766,18 @@ Play with Friends joins over an encrypted tunnel with an invite code ([docs/play
 
 ### Mods and API
 
+#### Scripts for mods
+
+Small mods written as scripts, in the style of KubeJS, with no compiler.
+
+<details><summary>Technical</summary>
+
+Waits for native mods to settle: the earlier plan ran Lua inside the WebAssembly sandbox, which is being removed. A script layer over the native hook points is to be designed.
+
+More: [docs/native-mods.md](docs/native-mods.md)
+
+</details>
+
 #### Orbital Laser on the normal game
 
 The community mod Orbital Laser, made for a fork of Horizon, running on the normal game and listed in the registry as the showcase of the mod API.
@@ -732,13 +790,13 @@ A pull request on [https://github.com/Stink-O/orbital-laser](https://github.com/
 
 #### Native versions of popular client mods
 
-Built-in versions of the client mods players ask for: block info on hover, a recipe viewer like JEI, a world map and schematic overlays.
+Built-in versions of the client mods players ask for: block info on hover, a world map, inventory tweaks and schematic overlays.
 
 <details><summary>Technical</summary>
 
-Done as extras: a mod list and menu, a minimap and a zoom ([docs/extras.md](docs/extras.md)). Left: block info tooltips, a recipe viewer (a contributor offered to port JEI if it becomes a native feature), a world map and a schematic overlay. They need the read-only interfaces `inventory-read`, `recipes`, `world-read` and `render` in the mod API, or they go into the game directly.
+Done: a mod list and menu, minimap, zoom, keystrokes, an FPS counter and a recipe viewer, as native mods (horizon-mods/native/). Asked for: an angled world map that shows hills, overhangs and caves, inventory tweaks (drag and scroll to move items), block info tooltips and schematic overlays.
 
-More: [docs/mods.md](docs/mods.md)
+More: [docs/extras.md](docs/extras.md) · [docs/native-mods.md](docs/native-mods.md)
 
 </details>
 
@@ -784,6 +842,16 @@ The game side is merged ([docs/controllers.md](docs/controllers.md)): pads read
 
 </details>
 
+#### Splitscreen
+
+Play with a friend on the same screen, each with a controller.
+
+<details><summary>Technical</summary>
+
+Issue [#2054](https://github.com/horizon-rust/horizon/issues/2054); a contributor is working on it. Two local players on the same world, each with their own camera and HUD, built on the server thread's multiplayer.
+
+</details>
+
 #### The full debug screen
 
 Vanilla's complete F3 screen: debug options, a profiler chart, ten-second captures and an atlas dump.
@@ -834,7 +902,7 @@ More graphics options: multisample anti-aliasing, anisotropic filtering and an e
 
 <details><summary>Technical</summary>
 
-Not implemented ([docs/graphics.md](docs/graphics.md)). Anisotropic filtering needs linear magnification in wgpu, which blurs close blocks, so close-up sharpness has to be kept first; MSAA would sit beside FXAA; exclusive fullscreen where the backend supports it.
+Not implemented ([docs/graphics.md](docs/graphics.md)). Anisotropic filtering needs linear magnification in wgpu, which blurs close blocks, so close-up sharpness has to be kept first; MSAA would sit beside FXAA, and SMAA or TAA are asked for too; exclusive fullscreen where the backend supports it.
 
 </details>
 
@@ -862,6 +930,18 @@ Issue [#1709](https://github.com/horizon-rust/horizon/issues/1709): aarch64 buil
 
 </details>
 
+#### Horizon on Windows ARM64
+
+A native Horizon for Windows on ARM computers, such as Snapdragon laptops.
+
+<details><summary>Technical</summary>
+
+Releases are x64 for Windows and Linux and arm64 for macOS. Needs an aarch64-pc-windows-msvc build in the release workflow and a machine to test on.
+
+More: [docs/release-flow.md](docs/release-flow.md)
+
+</details>
+
 #### Android, iOS and the browser
 
 Versions of Horizon for Android, iOS and web browsers. Nothing official yet; contributors have started the first pieces.
@@ -968,6 +1048,7 @@ Armour and tools in End city chests should come enchanted, as in vanilla.
 
 ## Recently shipped
 
+- **Microsoft sign-in** (launcher@0.2.17): Sign in with your Microsoft account in the launcher to play on online-mode servers. [docs/microsoft-account.md](docs/microsoft-account.md) · [#2879](https://github.com/horizon-rust/horizon/issues/2879)
 - **OpenGL for old computers** (v0.2.63): Horizon now starts on old PCs whose graphics card has no Vulkan or DirectX 12 driver: it switches to OpenGL by itself, and Options > Graphics can pick OpenGL by hand. [#1917](https://github.com/horizon-rust/horizon/issues/1917) · [#1920](https://github.com/horizon-rust/horizon/issues/1920) · [#1936](https://github.com/horizon-rust/horizon/issues/1936)
 - **Server resource packs** (v0.2.48): Servers can send you their resource pack: Horizon asks, downloads it and applies it, like vanilla. [#1562](https://github.com/horizon-rust/horizon/issues/1562) · [#1569](https://github.com/horizon-rust/horizon/issues/1569) · [#1570](https://github.com/horizon-rust/horizon/issues/1570)
 - **Single player on its own server thread** (v0.2.39): Single player runs on a server thread, as vanilla does, so the world keeps ticking smoothly while the window draws. [#1514](https://github.com/horizon-rust/horizon/issues/1514) · [docs/server-levels.md](docs/server-levels.md)

crates/horizon-client-core/src/component.rs

@@ -11,13 +11,18 @@ pub fn parse_snbt(input: &str) -> Result<(Value, usize), String> {
     let mut p = Parser {
         s: input.as_bytes(),
         i: 0,
+        depth: 0,
     };
     let v = p.value()?;
     Ok((v, p.i))
 }
+/// Nesting deeper than NBT's own limit (`NbtAccounter`'s 512) is refused
+/// rather than overflowing the stack.
+const SNBT_MAX_DEPTH: usize = 512;
 struct Parser<'a> {
     s: &'a [u8],
     i: usize,
+    depth: usize,
 }
 impl Parser<'_> {
     fn ws(&mut self) {
@@ -41,57 +46,22 @@ impl Parser<'_> {
         self.ws();
         match self.peek() {
             Some(b'{') => {
-                self.i += 1;
-                let mut map = Map::new();
-                self.ws();
-                if self.peek() == Some(b'}') {
-                    self.i += 1;
-                    return Ok(Value::Object(map));
-                }
-                loop {
-                    self.ws();
-                    let key = self.string()?;
-                    self.expect(b':')?;
-                    map.insert(key, self.value()?);
-                    self.ws();
-                    match self.peek() {
-                        Some(b',') => self.i += 1,
-                        Some(b'}') => {
-                            self.i += 1;
-                            return Ok(Value::Object(map));
-                        }
-                        _ => return Err("expected ',' or '}'".into()),
-                    }
+                if self.depth >= SNBT_MAX_DEPTH {
+                    return Err(format!("tag nesting too deep at {}", self.i));
                 }
+                self.depth += 1;
+                let v = self.object();
+                self.depth -= 1;
+                v
             }
             Some(b'[') => {
-                self.i += 1;
-                let mut list = Vec::new();
-                self.ws();
-                // Typed arrays [B;...], [I;...], [L;...].
-                if matches!(
-                    self.s.get(self.i..self.i + 2),
-                    Some([b'B' | b'I' | b'L', b';'])
-                ) {
-                    self.i += 2;
-                }
-                self.ws();
-                if self.peek() == Some(b']') {
-                    self.i += 1;
-                    return Ok(Value::Array(list));
-                }
-                loop {
-                    list.push(self.value()?);
-                    self.ws();
-                    match self.peek() {
-                        Some(b',') => self.i += 1,
-                        Some(b']') => {
-                            self.i += 1;
-                            return Ok(Value::Array(list));
-                        }
-                        _ => return Err("expected ',' or ']'".into()),
-                    }
+                if self.depth >= SNBT_MAX_DEPTH {
+                    return Err(format!("tag nesting too deep at {}", self.i));
                 }
+                self.depth += 1;
+                let v = self.array();
+                self.depth -= 1;
+                v
             }
             Some(b'"' | b'\'') => Ok(Value::String(self.string()?)),
             Some(_) => {
@@ -105,10 +75,20 @@ impl Parser<'_> {
                     _ => {
                         let digits = word
                             .trim_end_matches(['b', 'B', 's', 'S', 'l', 'L', 'f', 'F', 'd', 'D']);
-                        match (digits.parse::<i64>(), digits.parse::<f64>()) {
-                            (Ok(n), _) if digits.len() + 1 >= word.len() => Value::from(n),
-                            (_, Ok(f)) if digits.len() + 1 >= word.len() => Value::from(f),
-                            _ => Value::String(word),
+                        // Only digits (and an exponent) make a number: `nan`
+                        // or `Infinity`, which Rust's parse would take, stays
+                        // a string.
+                        if digits
+                            .bytes()
+                            .any(|c| c.is_ascii_alphabetic() && c != b'e' && c != b'E')
+                        {
+                            Value::String(word)
+                        } else {
+                            match (digits.parse::<i64>(), digits.parse::<f64>()) {
+                                (Ok(n), _) if digits.len() + 1 >= word.len() => Value::from(n),
+                                (_, Ok(f)) if digits.len() + 1 >= word.len() => Value::from(f),
+                                _ => Value::String(word),
+                            }
                         }
                     }
                 })
@@ -116,6 +96,59 @@ impl Parser<'_> {
             None => Err("expected a value".into()),
         }
     }
+    fn object(&mut self) -> Result<Value, String> {
+        self.i += 1;
+        let mut map = Map::new();
+        self.ws();
+        if self.peek() == Some(b'}') {
+            self.i += 1;
+            return Ok(Value::Object(map));
+        }
+        loop {
+            self.ws();
+            let key = self.string()?;
+            self.expect(b':')?;
+            map.insert(key, self.value()?);
+            self.ws();
+            match self.peek() {
+                Some(b',') => self.i += 1,
+                Some(b'}') => {
+                    self.i += 1;
+                    return Ok(Value::Object(map));
+                }
+                _ => return Err("expected ',' or '}'".into()),
+            }
+        }
+    }
+    fn array(&mut self) -> Result<Value, String> {
+        self.i += 1;
+        let mut list = Vec::new();
+        self.ws();
+        // Typed arrays [B;...], [I;...], [L;...].
+        if matches!(
+            self.s.get(self.i..self.i + 2),
+            Some([b'B' | b'I' | b'L', b';'])
+        ) {
+            self.i += 2;
+        }
+        self.ws();
+        if self.peek() == Some(b']') {
+            self.i += 1;
+            return Ok(Value::Array(list));
+        }
+        loop {
+            list.push(self.value()?);
+            self.ws();
+            match self.peek() {
+                Some(b',') => self.i += 1,
+                Some(b']') => {
+                    self.i += 1;
+                    return Ok(Value::Array(list));
+                }
+                _ => return Err("expected ',' or ']'".into()),
+            }
+        }
+    }
     fn unquoted(&mut self) -> String {
         let start = self.i;
         while let Some(c) = self.peek() {
@@ -351,4 +384,22 @@ mod tests {
         let t = to_text(&v, &mut |_| Text::empty());
         assert_eq!(t.spans[0].style.font, None);
     }
+
+    #[test]
+    fn snbt_nesting_is_bounded() {
+        let nest = |n: usize| format!("{}1{}", "[".repeat(n), "]".repeat(n));
+        assert!(parse_snbt(&nest(512)).is_ok());
+        assert!(parse_snbt(&nest(513)).is_err());
+        assert!(parse_snbt(&nest(100_000)).is_err());
+    }
+
+    #[test]
+    fn bare_words_that_look_numeric_stay_strings() {
+        let (v, _) = parse_snbt("{text:nan}").unwrap();
+        assert_eq!(v["text"], Value::String("nan".into()));
+        let (v, _) = parse_snbt("{text:Infinity}").unwrap();
+        assert_eq!(v["text"], Value::String("Infinity".into()));
+        let (v, _) = parse_snbt("{n:1.5}").unwrap();
+        assert_eq!(v["n"], Value::from(1.5));
+    }
 }

crates/horizon-client-core/src/lang.rs

@@ -40,6 +40,10 @@ static BIDIRECTIONAL: AtomicBool = AtomicBool::new(false);
 /// A source of resource files: the prepared root plus packs, highest priority last.
 pub trait ResourceSource {
     fn read(&self, path: &str) -> Option<Vec<u8>>;
+    /// Whether `path` is there, without reading it where the source can tell.
+    fn exists(&self, path: &str) -> bool {
+        self.read(path).is_some()
+    }
     /// The namespaces under `assets/` (resource packs may add their own).
     fn namespaces(&self) -> Vec<String> {
         vec!["minecraft".into()]
@@ -68,6 +72,9 @@ impl ResourceSource for std::path::PathBuf {
     fn read(&self, path: &str) -> Option<Vec<u8>> {
         std::fs::read(self.join(path)).ok()
     }
+    fn exists(&self, path: &str) -> bool {
+        self.join(path).is_file()
+    }
     fn namespaces(&self) -> Vec<String> {
         std::fs::read_dir(self.join("assets"))
             .into_iter()
@@ -190,7 +197,7 @@ pub fn available(sources: &[&dyn ResourceSource]) -> Vec<LanguageInfo> {
             for (code, info) in value["language"].as_object().into_iter().flatten() {
                 // Only languages whose file exists somewhere are selectable.
                 let file = format!("assets/minecraft/lang/{code}.json");
-                if code != DEFAULT && !sources.iter().any(|s| s.read(&file).is_some()) {
+                if code != DEFAULT && !sources.iter().any(|s| s.exists(&file)) {
                     continue;
                 }
                 found.insert(
@@ -259,6 +266,13 @@ mod tests {
         assert_eq!(en.get("horizon.options.controller"), Some("Controller"));
         let ru = Language::load(&[&empty], "ru_ru");
         assert_eq!(ru.get("horizon.options.controller"), Some("Геймпад"));
+        // Every bundled string carries both languages: a key added to one file
+        // and forgotten in the other shows as a key name on screen.
+        for key in en.map().keys() {
+            assert!(ru.get(key).is_some(), "{key} has no ru_ru value");
+        }
+        assert_eq!(en.get("horizon.pages.mods"), Some("Mods"));
+        assert_eq!(ru.get("horizon.pages.mods"), Some("Моды"));
     }
 
     #[test]
@@ -284,4 +298,26 @@ mod tests {
         );
         assert_eq!(langs[1].label(), "Français (France)");
     }
+
+    #[test]
+    fn languages_are_listed_without_reading_their_files() {
+        struct NoLangReads;
+        impl ResourceSource for NoLangReads {
+            fn read(&self, path: &str) -> Option<Vec<u8>> {
+                assert!(!path.contains("/lang/"), "read {path}");
+                (path == "assets/pack.mcmeta").then(|| {
+                    br#"{"language":{"fr_fr":{"name":"French"},"de_de":{"name":"German"}}}"#
+                        .to_vec()
+                })
+            }
+            fn exists(&self, path: &str) -> bool {
+                path == "assets/minecraft/lang/fr_fr.json"
+            }
+        }
+        let langs = available(&[&NoLangReads]);
+        assert_eq!(
+            langs.iter().map(|l| l.code.as_str()).collect::<Vec<_>>(),
+            ["en_us", "fr_fr"]
+        );
+    }
 }

crates/horizon-client-core/src/registries.rs

@@ -54,6 +54,9 @@ pub struct Registries {
     pub function_tags: Vec<String>,
     /// The block the source is looking at (relevant coordinates).
     pub target_block: Option<[i32; 3]>,
+    /// `ClientSuggestionProvider.getAbsoluteCoordinates`: the exact point of
+    /// that block hit, each coordinate as `%.2f` (`Locale.ROOT`).
+    pub target_point: Option<[String; 3]>,
     /// Every registry's element and tag ids (`minecraft:item` -> ...), as
     /// the server's registry access and reloadable registries hold them.
     pub by_registry: BTreeMap<String, RegistryIds>,

crates/horizon-client-core/src/scoreboard.rs

@@ -662,10 +662,22 @@ pub fn name_shown(own: Option<&Team>, viewer: Option<&Team>, v: NameView) -> boo
     }
     !v.hud_hidden && !v.is_camera && visible && !v.is_vehicle
 }
-/// `ServerPlayer.die`: whether a player's death message reaches the player
-/// themselves (the team broadcasts leave out the dying player).
-pub fn own_death_message_shown(team: Option<&Team>) -> bool {
-    team.is_none_or(|t| t.death_message_visibility == Visibility::Always)
+/// `ServerPlayer.die`: whether `other` hears the death message of `dying`
+/// (`broadcastSystemMessage`, `broadcastSystemToTeam` or
+/// `broadcastSystemToAllExceptTeam`, by the team's death message visibility).
+pub fn death_message_reaches(board: &Scoreboard, dying: &str, other: &str) -> bool {
+    let Some(team) = board.players_team(dying) else {
+        return true;
+    };
+    let same_team = board
+        .players_team(other)
+        .is_some_and(|t| t.name == team.name);
+    match team.death_message_visibility {
+        Visibility::Always => true,
+        Visibility::Never => false,
+        Visibility::HideForOtherTeams => same_team && other != dying,
+        Visibility::HideForOwnTeam => !same_team,
+    }
 }
 
 // ---- objectives and scores ---------------------------------------------

crates/horizon-client-core/src/text.rs

@@ -403,31 +403,7 @@ impl Text {
                     continue;
                 }
                 let Some(code) = chars.next() else { break };
-                let code = code.to_ascii_lowercase();
-                let next = if let Some(c) = COLORS.iter().find(|c| c.0 == code) {
-                    // Style.applyLegacyFormat: a colour clears the decorations.
-                    Style {
-                        color: Some(c.2),
-                        bold: Some(false),
-                        italic: Some(false),
-                        underlined: Some(false),
-                        strikethrough: Some(false),
-                        obfuscated: Some(false),
-                        ..style.clone()
-                    }
-                } else {
-                    let mut s = style.clone();
-                    match code {
-                        'k' => s.obfuscated = Some(true),
-                        'l' => s.bold = Some(true),
-                        'm' => s.strikethrough = Some(true),
-                        'n' => s.underlined = Some(true),
-                        'o' => s.italic = Some(true),
-                        'r' => s = span.style.clone(),
-                        _ => {}
-                    }
-                    s
-                };
+                let next = legacy_format(&style, code, &span.style);
                 if next != style {
                     if !current.is_empty() {
                         out.spans.push(Span {
@@ -588,6 +564,35 @@ fn style_json(style: &Style) -> Vec<(String, Value)> {
     out
 }
 
+/// `Style.applyLegacyFormat` for the code after a `§`, `§r` going back to
+/// `reset` (`StringDecomposer.iterateFormatted`); an unknown code changes nothing.
+pub fn legacy_format(style: &Style, code: char, reset: &Style) -> Style {
+    let code = code.to_ascii_lowercase();
+    if let Some(c) = COLORS.iter().find(|c| c.0 == code) {
+        // A colour clears the decorations.
+        return Style {
+            color: Some(c.2),
+            bold: Some(false),
+            italic: Some(false),
+            underlined: Some(false),
+            strikethrough: Some(false),
+            obfuscated: Some(false),
+            ..style.clone()
+        };
+    }
+    let mut s = style.clone();
+    match code {
+        'k' => s.obfuscated = Some(true),
+        'l' => s.bold = Some(true),
+        'm' => s.strikethrough = Some(true),
+        'n' => s.underlined = Some(true),
+        'o' => s.italic = Some(true),
+        'r' => s = reset.clone(),
+        _ => {}
+    }
+    s
+}
+
 /// TranslatableContents.decomposeTemplate: `%s` takes the next argument,
 /// `%n$s` a numbered one and `%%` is a percent sign. Malformed templates are
 /// shown verbatim.

crates/horizon-client-input/src/keybinds.rs

@@ -300,9 +300,8 @@ impl Default for KeyBinds {
     }
 }
 /// Each default key once, in order: two mappings that share a default key
-/// (Advancements and the debug profiler both on L) are one press of it, not
-/// two (the second would close the screen the first opened). Vanilla clicks
-/// both mappings, but the profiler one only acts with F3 held.
+/// (Pick Block and the spectator hotbar both on the middle button) are one
+/// press of it, not two.
 fn distinct<T: PartialEq>(keys: Vec<T>) -> Vec<T> {
     let mut out = Vec::with_capacity(keys.len());
     for k in keys {
@@ -368,6 +367,25 @@ impl KeyBinds {
             .map(|m| m.0)
             .filter(move |n| self.get(n) == key)
     }
+    /// The mappings bound to `key` that [`KeyBinds::translate_all`] follows:
+    /// all but the debug keys. Those act only with F3 held
+    /// (`KeyboardHandler.handleDebugKeys`, `debug_keys.rs` reads the physical
+    /// key and the binding itself); their defaults (A, S, D, T, L, 1 to 4...)
+    /// would otherwise turn the key back into its old gameplay meaning.
+    fn translated_mappings<'a>(&'a self, key: &'a str) -> impl Iterator<Item = &'static str> + 'a {
+        MAPPINGS
+            .iter()
+            .filter(|m| m.2 != "debug")
+            .map(|m| m.0)
+            .filter(move |n| self.get(n) == key)
+    }
+    /// Whether a mapping (other than a debug key) whose default is `key` was
+    /// bound elsewhere.
+    fn default_moved(&self, key: &str) -> bool {
+        MAPPINGS
+            .iter()
+            .any(|(n, d, c)| *d == key && *c != "debug" && !self.is_default(n))
+    }
     /// Translate a physical key into the default key of the mapping it is
     /// bound to, so game code written against vanilla defaults follows the
     /// player's bindings. `None` means the key now does nothing; mouse
@@ -384,7 +402,7 @@ impl KeyBinds {
             return vec![Ok(key)];
         };
         let bound: Vec<_> = self
-            .mappings_for(name)
+            .translated_mappings(name)
             .filter_map(|mapping| {
                 let default = Self::default_of(mapping);
                 match key_code(default) {
@@ -397,10 +415,7 @@ impl KeyBinds {
             return distinct(bound);
         }
         // An unbound key whose default meaning was moved elsewhere is inert.
-        if MAPPINGS
-            .iter()
-            .any(|(n, d, _)| *d == name && !self.is_default(n))
-        {
+        if self.default_moved(name) {
             return Vec::new();
         }
         vec![Ok(key)]
@@ -413,7 +428,7 @@ impl KeyBinds {
     pub fn translate_mouse_all(&self, button: MouseButton) -> Vec<Result<KeyCode, MouseButton>> {
         let name = mouse_name(button);
         let bound: Vec<_> = self
-            .mappings_for(&name)
+            .translated_mappings(&name)
             .filter_map(|mapping| {
                 let default = Self::default_of(mapping);
                 match mouse_button(default) {
@@ -425,10 +440,7 @@ impl KeyBinds {
         if !bound.is_empty() {
             return distinct(bound);
         }
-        if MAPPINGS
-            .iter()
-            .any(|(n, d, _)| *d == name && !self.is_default(n))
-        {
+        if self.default_moved(&name) {
             return Vec::new();
         }
         vec![Err(button)]
@@ -508,6 +520,29 @@ mod tests {
         assert_eq!(k.conflicts("key.forward"), ["key.jump"]);
     }
     #[test]
+    fn a_moved_key_keeps_no_default_action() {
+        // #3158: the debug keys (F3+A, F3+1...) share these keys' defaults,
+        // and must not hand them back their gameplay meaning.
+        let mut k = KeyBinds::default();
+        k.set("key.hotbar.1", "key.keyboard.q");
+        assert_eq!(k.translate_all(KeyCode::Digit1), []);
+        assert_eq!(
+            k.translate_all(KeyCode::KeyQ),
+            [Ok(KeyCode::KeyQ), Ok(KeyCode::Digit1)]
+        );
+        k.set("key.inventory", "key.keyboard.a");
+        k.set("key.left", "key.keyboard.e");
+        assert_eq!(k.translate_all(KeyCode::KeyA), [Ok(KeyCode::KeyE)]);
+        assert_eq!(k.translate_all(KeyCode::KeyE), [Ok(KeyCode::KeyA)]);
+        k.set("key.back", "key.keyboard.down");
+        assert_eq!(k.translate_all(KeyCode::KeyS), []);
+        // Keys left alone still act, and a moved debug key changes nothing.
+        k.set("key.debug.fpsCharts", "key.keyboard.9");
+        assert_eq!(k.translate_all(KeyCode::Digit2), [Ok(KeyCode::Digit2)]);
+        assert_eq!(k.translate_all(KeyCode::Digit9), [Ok(KeyCode::Digit9)]);
+        assert_eq!(k.translate_all(KeyCode::F3), [Ok(KeyCode::F3)]);
+    }
+    #[test]
     fn display_names() {
         assert_eq!(display_name("key.keyboard.w").plain(), "W");
         assert_eq!(display_name("key.keyboard.slash").plain(), "/");

crates/horizon-client-render/Cargo.toml

@@ -0,0 +1,67 @@
+[package]
+name = "horizon-client-render"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+rust-version = "1.90"
+description = "The client's world data, rendering and screens: chunks, meshing, light, streaming, the renderer, the HUD, menus and settings; no gameplay"
+
+[dependencies]
+horizon-assets = { path = "../horizon-assets" }
+horizon-bench = { path = "../horizon-bench" }
+horizon-client-core = { path = "../horizon-client-core" }
+horizon-client-input = { path = "../horizon-client-input" }
+horizon-command = { path = "../horizon-command" }
+horizon-core = { path = "../horizon-core" }
+horizon-hdr = { path = "../horizon-hdr" }
+horizon-items = { path = "../horizon-items" }
+horizon-protocol = { path = "../horizon-protocol" }
+horizon-shader-api = { path = "../horizon-shader-api" }
+horizon-shaders = { path = "../horizon-shaders" }
+horizon-telemetry = { path = "../horizon-telemetry", default-features = false, features = ["live"] }
+horizon-theme = { path = "../horizon-theme" }
+horizon-threads = { path = "../horizon-threads" }
+horizon-world = { path = "../horizon-world" }
+ab_glyph = "0.2.32"
+bytemuck = { version = "1.24", features = ["derive"] }
+# Sound (ALSA on Linux); the `audio` feature.
+cpal = { version = "0.16", optional = true }
+chrono = { version = "0.4.42", default-features = false, features = ["clock", "std"] }
+flate2 = { version = "1.1.10", default-features = false, features = ["zlib-rs", "runtime_detection"] }
+glam = "0.30"
+log = "0.4"
+miniz_oxide = "0.8"
+naga = { version = "30.0.1", features = ["wgsl-in", "hlsl-out"] }
+png = "0.18"
+pollster = "0.4"
+serde = { version = "1", features = ["derive"] }
+serde_json = { version = "1.0.151", features = ["raw_value"] }
+sha2 = "0.10.9"
+symphonia = { version = "0.5", default-features = false, features = ["ogg", "vorbis"] }
+unicode-bidi = "0.3.18"
+ureq = { version = "2", default-features = false, features = ["tls"] }
+wgpu = { version = "30.0.1", default-features = false, features = ["std", "parking_lot", "vulkan", "metal", "wgsl", "naga-ir"] }
+winit = "0.30.13"
+zip = { version = "2", default-features = false, features = ["deflate"] }
+
+[target.'cfg(unix)'.dependencies]
+rustix = { version = "1", default-features = false, features = ["std", "time"] }
+
+[target.'cfg(windows)'.dependencies]
+wgpu = { version = "30.0.1", default-features = false, features = ["dx12"] }
+
+[target.'cfg(not(target_os = "macos"))'.dependencies]
+wgpu = { version = "30.0.1", default-features = false, features = ["gles"] }
+
+[features]
+# Sound output: horizon-client's `audio` feature.
+audio = ["dep:cpal"]
+# Helpers horizon-client's tests build their fixtures with.
+test-support = []
+
+[lints]
+workspace = true
+
+[dev-dependencies]
+horizon-items = { path = "../horizon-items", features = ["test-support"] }
+naga = { version = "30.0.1", features = ["wgsl-in", "hlsl-out", "msl-out", "spv-out"] }

crates/horizon-client-render/src/assets.rs

@@ -42,11 +42,11 @@ impl HeightmapState for StateFacts {
 }
 #[derive(Clone)]
 pub struct Properties(Arc<Vec<StateFacts>>);
-#[cfg(test)]
+#[cfg(any(test, feature = "test-support"))]
 impl Properties {
     /// Heightmap facts for tests, per state: (air, has a fluid, blocks
     /// motion, blocks motion but is not leaves). State 0 is minecraft:air.
-    pub(crate) fn for_tests(states: &[(bool, bool, bool, bool)]) -> Self {
+    pub fn for_tests(states: &[(bool, bool, bool, bool)]) -> Self {
         Self(Arc::new(
             states
                 .iter()
@@ -196,7 +196,7 @@ impl Assets {
 impl RenderAssets {
     pub fn load(root: &Path, assets: &Assets) -> Result<Self> {
         let registry = assets.registry;
-        let mut sprites = crate::sprites::Sprites::default();
+        let mut sprites = crate::sprites::Sprites::with_disk_cache(root);
         for name in MATERIALS {
             sprites.insert(root, &format!("minecraft:block/{name}"))?;
         }
@@ -217,6 +217,7 @@ impl RenderAssets {
         for stage in 0..10 {
             sprites.insert(root, &format!("minecraft:block/destroy_stage_{stage}"))?;
         }
+        sprites.save_disk_cache();
         sprites.finish();
         // `finish` grows the buffer by doubling: keep only the bytes in use.
         sprites.pixels.shrink_to_fit();

crates/horizon-client-render/src/atlas_sources.rs

@@ -187,7 +187,14 @@ pub fn list_textures(root: &Path) -> Vec<String> {
             };
             for e in entries.flatten() {
                 let p = e.path();
-                if p.is_dir() {
+                // `file_type` comes with the listing; `Path::is_dir` is a stat per
+                // entry, kept for links (which it follows).
+                let dir = match e.file_type() {
+                    Ok(t) if t.is_symlink() => p.is_dir(),
+                    Ok(t) => t.is_dir(),
+                    Err(_) => p.is_dir(),
+                };
+                if dir {
                     stack.push(p);
                 } else if p.extension().is_some_and(|x| x == "png")
                     && let Ok(rel) = p.strip_prefix(&base)

crates/horizon-client-render/src/biome.rs

@@ -256,6 +256,10 @@ impl Biomes {
             .copied()
             .unwrap_or(0)
     }
+    /// Whether the game has the biome `name`.
+    pub fn contains(&self, name: &str) -> bool {
+        self.index.contains_key(name)
+    }
     pub fn get(&self, id: u16) -> &BiomeInfo {
         &self.list[usize::from(id).min(self.list.len() - 1)]
     }

crates/horizon-client-render/src/block_entity_render.rs

@@ -654,10 +654,20 @@ fn sign_text_calls(
         .collect()
 }
 
+/// How far the text of an outlined call sits in front of its outline, in
+/// text units (`Font.DisplayMode.POLYGON_OFFSET`, see `draw_text`).
+const TEXT_OVER_OUTLINE: f32 = 0.05;
+
 /// Draws a text call with the font atlas: 8x8 glyph cells, the outline as
 /// eight one-pixel offsets under the text.
+///
+/// `TextFeatureRenderer.renderText` draws the outline glyphs NORMAL and the
+/// text over them POLYGON_OFFSET, so the coplanar text always wins the depth
+/// test. Here both share one mesh, so the text is lifted a hair towards the
+/// reader instead (a twentieth of a font pixel, invisible) rather than
+/// z-fighting with the outline under it.
 fn draw_text(scene: &Scene, call: &TextCall, out: &mut Vec<Vertex>) {
-    let mut emit = |dx: f32, dy: f32, argb: u32| {
+    let mut emit = |dx: f32, dy: f32, z: f32, argb: u32| {
         let mut x = call.x + dx;
         let y0 = call.y + dy;
         for ch in call.text.chars() {
@@ -672,7 +682,7 @@ fn draw_text(scene: &Scene, call: &TextCall, out: &mut Vec<Vertex>) {
                         normal: [0; 4],
                         pos: call
                             .matrix
-                            .transform_point3(Vec3::new(cx, cy, 0.0))
+                            .transform_point3(Vec3::new(cx, cy, z))
                             .to_array(),
                         uv,
                         layer: 0,
@@ -697,10 +707,15 @@ fn draw_text(scene: &Scene, call: &TextCall, out: &mut Vec<Vertex>) {
             (0.0, 1.0),
             (1.0, 1.0),
         ] {
-            emit(dx, dy, call.outline);
+            emit(dx, dy, 0.0, call.outline);
         }
     }
-    emit(0.0, 0.0, call.color);
+    let z = if call.outline != 0 {
+        TEXT_OVER_OUTLINE
+    } else {
+        0.0
+    };
+    emit(0.0, 0.0, z, call.color);
 }
 
 /// Block-entity fields the level ticks, at one position (vanilla's own field
@@ -2258,6 +2273,69 @@ mod tests {
         assert_eq!(out[2].uv, [0.5, 0.5]);
     }
 
+    /// TextFeatureRenderer.renderText: an outlined call's text is drawn over
+    /// its outline (Font.DisplayMode.POLYGON_OFFSET), never level with it,
+    /// and plain text stays on the sign's plane.
+    #[test]
+    fn outlined_sign_text_sits_in_front_of_its_outline() {
+        let world = World::new(BlockStateId(0), 1);
+        let sprites = HashMap::new();
+        let glyph = |_: char| {
+            let rect = Rect {
+                u0: 0.0,
+                v0: 0.0,
+                u1: 0.0625,
+                v1: 0.0625,
+                w: 8,
+                h: 8,
+            };
+            (Some(rect), 6.0)
+        };
+        let scene = Scene {
+            camera: DVec3::ZERO,
+            orientation: Quat::IDENTITY,
+            anim: &|_| BlockAnim::default(),
+            texts: None,
+            partial: 0.0,
+            game_time: 0,
+            max_y: 320,
+            world: &world,
+            sprites: &sprites,
+            nether: false,
+            lid: &|_| 0.0,
+            sign: &|_| None,
+            banner: &|_| Vec::new(),
+            skull: &|_| None,
+            glyph: &glyph,
+            glyphs: 0,
+        };
+        let mut call = TextCall {
+            matrix: Mat4::IDENTITY,
+            x: 0.0,
+            y: 0.0,
+            text: "Hi".into(),
+            color: 0xFFFF_FF00,
+            outline: 0xFF33_3300,
+            light: 240 | 240 << 8,
+        };
+        let mut out = Vec::new();
+        draw_text(&scene, &call, &mut out);
+        // Eight outline copies, then the text, four corners a glyph.
+        assert_eq!(out.len(), 9 * 2 * 4);
+        let (outline, text) = out.split_at(8 * 2 * 4);
+        let front = outline.iter().map(|v| v.pos[2]).fold(f32::MIN, f32::max);
+        assert!(
+            text.iter().all(|v| v.pos[2] > front),
+            "text z {:?} not in front of the outline at {front}",
+            text.iter().map(|v| v.pos[2]).collect::<Vec<_>>()
+        );
+        call.outline = 0;
+        out.clear();
+        draw_text(&scene, &call, &mut out);
+        assert_eq!(out.len(), 2 * 4);
+        assert!(out.iter().all(|v| v.pos[2] == 0.0));
+    }
+
     #[test]
     fn cached_sign_text_matches_and_follows_changes() {
         let renderer = BlockEntityRenderer {

crates/horizon-client-render/src/brewing.rs

@@ -14,14 +14,19 @@ pub use horizon_client_core::potions::{
     BASE_POTION_COLOR, Category, EFFECTS, EffectDef, POTIONS, PotionDef, effect, namespaced,
     potion, potion_color,
 };
-/// `MobEffectUtil.formatDuration` at 20 TPS: m:ss or h:mm:ss.
+/// `MobEffectUtil.formatDuration` at 20 TPS.
 pub fn format_duration(ticks: i32) -> String {
-    let secs = ticks / 20;
+    format_tick_duration(ticks, 20.0)
+}
+/// `StringUtil.formatTickDuration`: mm:ss, or hh:mm:ss from an hour up, every
+/// field two digits.
+pub fn format_tick_duration(ticks: i32, tick_rate: f32) -> String {
+    let secs = (ticks as f32 / tick_rate).floor() as i32;
     let (h, m, s) = (secs / 3600, secs / 60 % 60, secs % 60);
     if h > 0 {
-        format!("{h}:{m:02}:{s:02}")
+        format!("{h:02}:{m:02}:{s:02}")
     } else {
-        format!("{m}:{s:02}")
+        format!("{m:02}:{s:02}")
     }
 }
 /// `item.minecraft.potion.effect.<name>` style translation key for a potion item.
@@ -317,10 +322,14 @@ mod tests {
             potion_name_key("minecraft:splash_potion", Some("minecraft:long_swiftness")),
             "item.minecraft.splash_potion.effect.swiftness"
         );
-        assert_eq!(format_duration(9600), "8:00");
-        assert_eq!(format_duration(450), "0:22");
+        assert_eq!(format_duration(9600), "08:00");
+        assert_eq!(format_duration(450), "00:22");
+        assert_eq!(format_duration(140), "00:07");
+        assert_eq!(format_duration(1800), "01:30");
+        assert_eq!(format_duration(72000), "01:00:00");
+        assert_eq!(format_tick_duration(9600, 40.0), "04:00");
         let t = tooltip(Some("minecraft:strong_poison"), 1.0, &|_| None);
-        assert_eq!(t[0].0, "poison II (0:21)");
+        assert_eq!(t[0].0, "poison II (00:21)");
         assert_eq!(POTIONS.len(), 46);
     }
 
@@ -377,4 +386,23 @@ mod tests {
         stand.tick(&brewing, &items, &providers);
         assert_eq!(stand.brew_time, 0);
     }
+
+    /// #3312: `PotionContents.getPotionDescription` names the effects with
+    /// translatable components, so a Russian game reads them from ru_ru.json
+    /// (the prepared one; skipped without it), as the tooltip's other lines.
+    #[test]
+    fn effect_lines_read_the_selected_language() {
+        let root = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+            .join("../../.local/horizon-client")
+            .join(horizon_core::VANILLA_VERSION);
+        if !root.join("assets/minecraft/lang/ru_ru.json").exists() {
+            return;
+        }
+        let ru = crate::lang::Language::load(&[&root], "ru_ru");
+        let translate = |key: &str| ru.get(key).map(str::to_owned);
+        let lines = tooltip(Some("minecraft:turtle_master"), 0.125, &translate);
+        assert_eq!(lines.len(), 2);
+        assert!(lines[0].0.starts_with("Замедление IV ("), "{lines:?}");
+        assert!(lines[1].0.starts_with("Сопротивление III ("), "{lines:?}");
+    }
 }

crates/horizon-client-render/src/camera.rs

@@ -653,18 +653,57 @@ pub fn modify_fov_based_on_death_or_fluid(
     fov
 }
 
-/// `ClientAvatarState`: the walked distance and view bob of a player.
+/// `ClientAvatarState`: the walked distance, view bob and cloak of a player.
 #[derive(Clone, Copy, Debug, Default, PartialEq)]
 pub struct AvatarBob {
     pub walk_dist: f32,
     pub walk_dist_o: f32,
     pub bob: f32,
     pub bob_o: f32,
+    /// `xCloak`, `yCloak`, `zCloak`: a point trailing the player, which the cape leans from.
+    pub cloak: [f64; 3],
+    pub cloak_o: [f64; 3],
 }
 impl AvatarBob {
-    /// `ClientAvatarState.tick` (at the start of `AbstractClientPlayer.tick`).
-    pub fn tick(&mut self) {
+    /// `ClientAvatarState.tick` (at the start of `AbstractClientPlayer.tick`)
+    /// with the player's position then: `moveCloak` eases the cloak a quarter
+    /// of the way there, or puts it there from 10 blocks away.
+    pub fn tick(&mut self, position: [f64; 3]) {
         self.walk_dist_o = self.walk_dist;
+        self.cloak_o = self.cloak;
+        for i in 0..3 {
+            let d = position[i] - self.cloak[i];
+            if d > 10.0 || d < -10.0 {
+                self.cloak[i] = position[i];
+                self.cloak_o[i] = position[i];
+            } else {
+                self.cloak[i] += d * 0.25;
+            }
+        }
+    }
+    /// `AvatarRenderer.extractCapeState`: the cape's `capeFlap`, `capeLean`
+    /// and `capeLean2` (degrees) for the player at `position` (interpolated)
+    /// with its body turned `body_yaw` and its `fallFlyingScale`.
+    pub fn cape(
+        &self,
+        partial: f32,
+        position: [f64; 3],
+        body_yaw: f32,
+        fall_flying_scale: f32,
+    ) -> [f32; 3] {
+        let d: [f64; 3] = std::array::from_fn(|i| {
+            lerp_d(f64::from(partial), self.cloak_o[i], self.cloak[i]) - position[i]
+        });
+        let rad = f64::from(body_yaw * DEG_TO_RAD);
+        let (sin, cos) = (f64::from(trig::sin(rad)), f64::from(-trig::cos(rad)));
+        let mut flap = (d[1] as f32 * 10.0).clamp(-6.0, 32.0);
+        let lean = ((d[0] * sin + d[2] * cos) as f32 * 100.0 * (1.0 - fall_flying_scale))
+            .clamp(0.0, 150.0);
+        let lean2 = ((d[0] * cos - d[2] * sin) as f32 * 100.0).clamp(-20.0, 20.0);
+        let bob = self.interpolated_bob(partial);
+        let walk = lerp(partial, self.walk_dist_o, self.walk_dist);
+        flap += trig::sin(f64::from(walk * 6.0)) * 32.0 * bob;
+        [flap, lean, lean2]
     }
     /// `LocalPlayer.move`: `addWalkedDistance(Mth.length(dx, dz) * 0.6F)`
     /// with the float horizontal displacement.
@@ -795,6 +834,23 @@ pub fn spinning_effect_matrix(intensity: f32, angle_degrees: f32) -> glam::Mat4
 
 #[cfg(test)]
 mod tests {
+    /// `moveCloak` trails a quarter of the way, jumps from 10 blocks away; the
+    /// cape leans back as the player walks forward (south, body yaw 0).
+    #[test]
+    fn the_cloak_trails_the_player() {
+        let mut a = super::AvatarBob::default();
+        a.tick([0.0, 64.0, 0.0]);
+        assert_eq!((a.cloak, a.cloak_o), ([0.0, 64.0, 0.0], [0.0, 64.0, 0.0]));
+        a.tick([0.0, 64.0, 1.0]);
+        assert_eq!(a.cloak, [0.0, 64.0, 0.25]);
+        let [flap, lean, lean2] = a.cape(1.0, [0.0, 64.0, 1.0], 0.0, 0.0);
+        assert_eq!((flap, lean, lean2), (0.0, 75.0, 0.0));
+        // Falling lifts the flap, at most 32 degrees.
+        assert_eq!(a.cape(1.0, [0.0, 60.0, 0.25], 0.0, 0.0)[0], 32.0);
+        // Gliding takes the lean away.
+        assert_eq!(a.cape(1.0, [0.0, 64.0, 1.0], 0.0, 1.0)[1], 0.0);
+    }
+
     #[test]
     fn depth_far_covers_the_cloud_range() {
         // renderDistance 2 with the default Cloud Distance (128 chunks).

crates/horizon-client-render/src/chunk/block_entity.rs

@@ -230,7 +230,7 @@ pub struct Info {
 /// `VibrationSelector`: the closest, then highest-frequency candidate of a tick.
 #[derive(Clone, Debug, Default, PartialEq)]
 pub struct Selector {
-    pub(crate) current: Option<(Info, i64)>,
+    pub current: Option<(Info, i64)>,
 }
 /// `VibrationSystem.Data`.
 #[derive(Clone, Debug, Default, PartialEq)]
@@ -278,7 +278,7 @@ pub struct SpawnData {
 /// Which `SpawnData` is next: one of the potentials (the same object in
 /// vanilla, so changing it changes the potential) or its own.
 #[derive(Clone, Debug, PartialEq)]
-pub(crate) enum Next {
+pub enum Next {
     Potential(usize),
     Own(SpawnData),
 }
@@ -288,7 +288,7 @@ pub struct Spawner {
     pub spawn_delay: i32,
     /// `SpawnPotentials`: data and weight.
     pub potentials: Vec<(SpawnData, i32)>,
-    pub(crate) next: Option<Next>,
+    pub next: Option<Next>,
     pub min_spawn_delay: i32,
     pub max_spawn_delay: i32,
     pub spawn_count: i32,
@@ -301,6 +301,24 @@ pub struct Spawner {
     pub spin: f64,
     pub o_spin: f64,
 }
+impl Default for Spawner {
+    fn default() -> Self {
+        Self {
+            spawn_delay: 20,
+            potentials: Vec::new(),
+            next: None,
+            min_spawn_delay: 200,
+            max_spawn_delay: 800,
+            spawn_count: 4,
+            max_nearby_entities: 6,
+            required_player_range: 16,
+            spawn_range: 4,
+            client_delay: 20,
+            spin: 0.0,
+            o_spin: 0.0,
+        }
+    }
+}
 /// `TrialSpawnerConfig`.
 #[derive(Clone, Debug, PartialEq)]
 pub struct TrialConfig {
@@ -314,6 +332,26 @@ pub struct TrialConfig {
     pub loot_tables_to_eject: Vec<(String, i32)>,
     pub items_to_drop_when_ominous: String,
 }
+impl Default for TrialConfig {
+    /// `TrialSpawnerConfig.Builder`'s defaults.
+    fn default() -> Self {
+        Self {
+            spawn_range: 4,
+            total_mobs: 6.0,
+            simultaneous_mobs: 2.0,
+            total_mobs_added_per_player: 2.0,
+            simultaneous_mobs_added_per_player: 1.0,
+            ticks_between_spawn: 40,
+            spawn_potentials: Vec::new(),
+            loot_tables_to_eject: vec![
+                ("minecraft:spawners/trial_chamber/consumables".into(), 1),
+                ("minecraft:spawners/trial_chamber/key".into(), 1),
+            ],
+            items_to_drop_when_ominous:
+                "minecraft:spawners/trial_chamber/items_to_drop_when_ominous".into(),
+        }
+    }
+}
 /// A `Holder<TrialSpawnerConfig>` as saved: a registry id
 /// (`minecraft:trial_chamber/breeze/normal`) or an inline config.
 #[derive(Clone, Debug, Default, PartialEq)]
@@ -347,6 +385,28 @@ pub struct TrialSpawner {
     /// and their weights (the rolled counts).
     pub dispensing: Option<Vec<ItemStack>>,
 }
+impl Default for TrialSpawner {
+    fn default() -> Self {
+        Self {
+            normal: ConfigSlot::default(),
+            ominous: ConfigSlot::default(),
+            target_cooldown_length: 36000,
+            required_player_range: 14,
+            detected_players: Vec::new(),
+            current_mobs: Vec::new(),
+            cooldown_ends_at: 0,
+            next_mob_spawns_at: 0,
+            total_mobs_spawned: 0,
+            next_spawn_data: None,
+            ejecting_loot_table: None,
+            is_ominous: false,
+            has_display: false,
+            spin: 0.0,
+            o_spin: 0.0,
+            dispensing: None,
+        }
+    }
+}
 /// `VaultConfig`.
 #[derive(Clone, Debug, PartialEq)]
 pub struct VaultConfig {

crates/horizon-client-render/src/containers.rs

@@ -42,6 +42,45 @@ pub fn recipe_used_key(id: &str) -> String {
 /// A hopper's slots: the only plain container with five.
 pub const HOPPER_SLOTS: usize = 5;
 
+/// `getDefaultName` of the `BaseContainerBlockEntity` that `block` holds: the
+/// translation key of its menu's title when it has no custom name. Copper
+/// chests hold a `ChestBlockEntity`, shulker boxes of every colour a
+/// `ShulkerBoxBlockEntity`.
+pub fn default_name_key(block: &str) -> Option<&'static str> {
+    Some(match block {
+        "minecraft:chest" | "minecraft:trapped_chest" => "container.chest",
+        n if n.ends_with("copper_chest") => "container.chest",
+        "minecraft:barrel" => "container.barrel",
+        n if n.ends_with("shulker_box") => "container.shulkerBox",
+        "minecraft:dispenser" => "container.dispenser",
+        "minecraft:dropper" => "container.dropper",
+        "minecraft:hopper" => "container.hopper",
+        "minecraft:furnace" => "container.furnace",
+        "minecraft:smoker" => "container.smoker",
+        "minecraft:blast_furnace" => "container.blast_furnace",
+        "minecraft:brewing_stand" => "container.brewing",
+        "minecraft:crafter" => "container.crafter",
+        _ => return None,
+    })
+}
+
+/// `BaseContainerBlockEntity.getDisplayName` (`getName`), the title of the
+/// `ClientboundOpenScreenPacket` that opens it: the block entity's custom
+/// name (`CustomName`, a literal), else its default name.
+pub fn display_name(custom: Option<&str>, default_key: &str) -> horizon_world::nbt::Tag {
+    match custom {
+        Some(name) => horizon_protocol::text::literal(name),
+        None => horizon_protocol::text::translatable(default_key, &[]),
+    }
+}
+
+/// `ChestBlock.MENU_PROVIDER_COMBINER`'s `getDisplayName` for a double chest:
+/// the first half's custom name (the right half, `DoubleBlockCombiner`'s
+/// `FIRST`), else the second's, else `container.chestDouble`.
+pub fn double_chest_name(first: Option<&str>, second: Option<&str>) -> horizon_world::nbt::Tag {
+    display_name(first.or(second), "container.chestDouble")
+}
+
 impl Campfire {
     /// `placeFood`'s slot: the first empty one, given the item's
     /// `campfire_cooking` time; it takes one item of `held`.
@@ -378,6 +417,58 @@ impl BlockEntity {
 }
 pub use crate::providers::Providers;
 
+/// A `ChestBlock`, which `ChestBlock.combine` can join into a double chest:
+/// chests, trapped chests and copper chests in every weathering state, waxed
+/// or not (`CopperChestBlock` extends `ChestBlock`). Ender chests are
+/// `EnderChestBlock`s and always single.
+pub fn is_chest_block(name: &str) -> bool {
+    matches!(name, "minecraft:chest" | "minecraft:trapped_chest") || name.ends_with("copper_chest")
+}
+
+/// A chest block's name with its `type` and `facing` properties.
+#[derive(Clone, Copy, Debug)]
+pub struct ChestHalf<'a> {
+    pub block: &'a str,
+    pub kind: &'a str,
+    pub facing: &'a str,
+}
+
+impl ChestHalf<'_> {
+    /// `ChestBlock.getConnectedDirection` as an (x, z) step to the other
+    /// half: clockwise from the facing for a left half, counter-clockwise for
+    /// a right one. None for a single chest.
+    pub fn connected_step(&self) -> Option<(i32, i32)> {
+        let step = |facing: &str| match facing {
+            "north" => Some((0, -1)),
+            "south" => Some((0, 1)),
+            "west" => Some((-1, 0)),
+            "east" => Some((1, 0)),
+            _ => None,
+        };
+        let (x, z) = step(self.facing)?;
+        // Turning clockwise seen from above takes (x, z) to (-z, x).
+        match self.kind {
+            "left" => Some((-z, x)),
+            "right" => Some((z, -x)),
+            _ => None,
+        }
+    }
+
+    /// `DoubleBlockCombiner.combineWithNeigbour` as `ChestBlock.combine` calls
+    /// it: `other`, the block in this half's connected direction, is its other
+    /// half when it is the same block, a half of the other side and faces the
+    /// same way. Copper chests in different weathering states never join
+    /// (`CopperChestBlock` keeps both halves in one state instead).
+    pub fn pairs_with(&self, other: &ChestHalf) -> bool {
+        is_chest_block(self.block)
+            && self.kind != "single"
+            && other.block == self.block
+            && other.kind != "single"
+            && other.kind != self.kind
+            && other.facing == self.facing
+    }
+}
+
 /// `AbstractFurnaceBlockEntity.createExperience`: `count * experience`, floored, and one
 /// more with the chance of what is left over (a level random draw only when there is some).
 pub fn create_experience(

crates/horizon-client-render/src/crash.rs

@@ -330,7 +330,7 @@ pub fn stack_lines(backtrace: &str, from_panic: bool) -> String {
     // separator the build machine used.
     let manifest = env!("CARGO_MANIFEST_DIR").replace('\\', "/");
     let root = manifest
-        .strip_suffix("crates/horizon-client")
+        .strip_suffix("crates/horizon-client-render")
         .unwrap_or(&manifest);
     let mut frames: Vec<(String, Option<String>)> = Vec::new();
     for line in backtrace.lines() {
@@ -605,7 +605,7 @@ mod tests {
         );
         assert_eq!(
             stack_lines(&bt, true),
-            "horizon_client::crash::debug_crash_tick (crates/horizon-client/src/crash.rs:359:9)\nwinit::dispatch (winit-0.30.13/src/event_loop.rs:642:56)\nmain\n"
+            "horizon_client::crash::debug_crash_tick (crates/horizon-client-render/src/crash.rs:359:9)\nwinit::dispatch (winit-0.30.13/src/event_loop.rs:642:56)\nmain\n"
         );
     }
 

crates/horizon-client-render/src/datapack.rs

@@ -2,7 +2,10 @@
 //! the parts of them commands use: `.mcfunction` functions (with macros and
 //! line continuation), function tags and predicates.
 use crate::zip::Zip;
-use horizon_world::nbt::Tag;
+use horizon_world::{
+    nbt::Tag,
+    worldgen::overrides::{self, PackFile, WorldgenOverrides},
+};
 use std::{
     collections::BTreeMap,
     path::{Path, PathBuf},
@@ -125,6 +128,114 @@ pub fn discover(world: &Path) -> Vec<DataPack> {
     packs
 }
 
+// ---- Create World ------------------------------------------------------------
+
+/// Create World's Data Packs screen (`PackSelectionScreen` on vanilla's
+/// `mcworld-` folder): the folder's packs (`PackSource.WORLD`) and the
+/// built-in one (`resources` holds its `pack.png`), which can be unselected
+/// and stays at the bottom. Horizon has no experiments, so their feature
+/// packs are not offered.
+pub fn screen_packs(dir: &Path, resources: &Path) -> Vec<crate::pack_screen::PackInfo> {
+    use crate::{
+        pack_screen::{Compat, PackInfo, Source, load_icon},
+        packs::Position,
+        text::{Style, Text},
+    };
+    let format = horizon_core::version::DATA_PACK_FORMAT;
+    let mut infos: Vec<PackInfo> = crate::packs::folder(dir, format)
+        .into_iter()
+        .map(|p| PackInfo {
+            icon: p.icon_png().as_deref().and_then(load_icon),
+            id: p.id,
+            title: p.title,
+            description: p.raw_description,
+            description_style: p.description_style,
+            source: Source::World,
+            compat: p.compatibility,
+            required: false,
+            position: Position::Top,
+            fixed: false,
+        })
+        .collect();
+    infos.push(PackInfo {
+        id: "vanilla".into(),
+        title: Text::translate("dataPack.vanilla.name", &[]),
+        description: Text::translate("dataPack.vanilla.description", &[]),
+        description_style: Style::default(),
+        source: Source::BuiltIn,
+        compat: Compat::Compatible,
+        icon: std::fs::read(resources.join("pack.png"))
+            .ok()
+            .as_deref()
+            .and_then(load_icon),
+        required: false,
+        position: Position::Bottom,
+        fixed: false,
+    });
+    infos
+}
+/// A new empty folder for Create World's packs
+/// (`Files.createTempDirectory("mcworld-")`).
+pub fn temp_folder() -> std::io::Result<PathBuf> {
+    let nanos = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_nanos();
+    let dir = std::env::temp_dir().join(format!("mcworld-{}-{nanos}", std::process::id()));
+    std::fs::create_dir_all(&dir)?;
+    Ok(dir)
+}
+/// What's in a folder of packs, to notice packs added or removed while the
+/// screen shows it (`PackSelectionScreen.Watcher`).
+pub fn folder_stamp(dir: &Path) -> Vec<(String, Option<std::time::SystemTime>)> {
+    let mut stamp: Vec<_> = std::fs::read_dir(dir)
+        .into_iter()
+        .flatten()
+        .flatten()
+        .map(|e| {
+            let modified = e.metadata().and_then(|m| m.modified()).ok();
+            (e.file_name().to_string_lossy().into_owned(), modified)
+        })
+        .collect();
+    stamp.sort();
+    stamp
+}
+/// Create World's packs into the new world before it opens
+/// (`copyTempDataPackDirToNewWorld`): every pack of `dir` goes to
+/// `<world>/datapacks`, and `datapacks.json` enables those `selected`
+/// (lowest priority first) and disables the rest.
+pub fn install(dir: &Path, world: &Path, selected: &[String]) -> Result<(), String> {
+    let err = |p: &Path, e: std::io::Error| format!("{}: {e}", p.display());
+    let target = world.join("datapacks");
+    std::fs::create_dir_all(&target).map_err(|e| err(&target, e))?;
+    let mut disabled = Vec::new();
+    for pack in crate::packs::folder(dir, horizon_core::version::DATA_PACK_FORMAT) {
+        let (crate::packs::Source::Dir(from) | crate::packs::Source::Zip(from)) = &pack.source;
+        copy(from, &target.join(pack.id.trim_start_matches("file/")))?;
+        if !selected.contains(&pack.id) {
+            disabled.push(pack.id);
+        }
+    }
+    if !selected.iter().any(|id| id == "vanilla") {
+        disabled.push("vanilla".into());
+    }
+    let json = serde_json::json!({ "enabled": selected, "disabled": disabled });
+    let file = world.join("datapacks.json");
+    std::fs::write(&file, json.to_string()).map_err(|e| err(&file, e))
+}
+/// A file, or a folder and everything in it.
+fn copy(from: &Path, to: &Path) -> Result<(), String> {
+    let err = |e: std::io::Error| format!("{} -> {}: {e}", from.display(), to.display());
+    if !from.is_dir() {
+        return std::fs::copy(from, to).map(drop).map_err(err);
+    }
+    std::fs::create_dir_all(to).map_err(err)?;
+    for e in std::fs::read_dir(from).map_err(err)?.flatten() {
+        copy(&e.path(), &to.join(e.file_name()))?;
+    }
+    Ok(())
+}
+
 // ---- functions ---------------------------------------------------------------
 
 /// A `.mcfunction`: plain command lines and macro lines.
@@ -421,9 +532,138 @@ fn hash_normalize(s: &str) -> String {
     }
 }
 
+/// The ids of `packs` (a world's, from `discover`) that are enabled, lowest
+/// priority first: those `<world>/datapacks.json` lists as enabled, in its
+/// order, then every pack it lists neither way, in name order.
+pub fn enabled_ids(world: &Path, packs: &[DataPack]) -> Vec<String> {
+    let saved: Option<serde_json::Value> = std::fs::read(world.join("datapacks.json"))
+        .ok()
+        .and_then(|b| serde_json::from_slice(&b).ok());
+    let list = |key: &str| -> Vec<String> {
+        saved
+            .as_ref()
+            .and_then(|v| v[key].as_array())
+            .map(|a| {
+                a.iter()
+                    .filter_map(|s| s.as_str().map(str::to_owned))
+                    .collect()
+            })
+            .unwrap_or_default()
+    };
+    let disabled = list("disabled");
+    let mut enabled: Vec<String> = list("enabled")
+        .into_iter()
+        .filter(|id| packs.iter().any(|p| &p.id == id))
+        .collect();
+    for p in packs {
+        if !enabled.contains(&p.id) && !disabled.contains(&p.id) {
+            enabled.push(p.id.clone());
+        }
+    }
+    enabled
+}
+
+// ---- worldgen ----------------------------------------------------------------
+
+/// The worldgen entries of `packs` (lowest priority first, the built-in pack
+/// left out: the prepared bundles are it) for the chunk generator, and what
+/// it leaves out, for the log. `biomes` says which biomes the game has: a
+/// pack's new biome is left out (the game has no colours, sounds or id for it).
+pub fn worldgen_overrides(
+    packs: &[&DataPack],
+    biomes: impl Fn(&str) -> bool,
+) -> (WorldgenOverrides, Vec<String>) {
+    let mut out = WorldgenOverrides::default();
+    let mut not_read: BTreeMap<String, usize> = BTreeMap::new();
+    let mut warnings = Vec::new();
+    for pack in packs {
+        for file in pack.list_kinds(&overrides::PACK_KINDS) {
+            let read = || String::from_utf8(pack.read(&file)?).ok();
+            match out.add_file(&pack.id, &file, read) {
+                PackFile::Read | PackFile::Other => {}
+                PackFile::DimensionType { id, min_y, height } => warnings.push(format!(
+                    "{}: dimension type {id} (min_y {min_y}, height {height}) is not used: \
+                     the dimension keeps its vanilla build height",
+                    pack.id
+                )),
+                PackFile::NotRead(kind) => {
+                    *not_read.entry(format!("{}: {kind}", pack.id)).or_default() += 1
+                }
+                PackFile::Unreadable => warnings.push(format!("{}: {file}: unreadable", pack.id)),
+            }
+        }
+    }
+    warnings.extend(out.finish(biomes));
+    for (kind, files) in not_read {
+        warnings.push(format!("{kind}: {files} files the generator does not read"));
+    }
+    (out, warnings)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
+
+    #[test]
+    fn enabled_packs_override_worldgen_in_order() {
+        let dir = std::env::temp_dir().join(format!("hz-datapack-worldgen-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&dir);
+        let write = |pack: &str, p: &str, t: &str| {
+            let path = dir.join("datapacks").join(pack).join(p);
+            std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+            std::fs::write(path, t).unwrap();
+        };
+        for pack in ["a", "b", "off"] {
+            write(pack, "pack.mcmeta", "{}");
+            write(pack, "data/minecraft/worldgen/noise/cave.json", pack);
+            write(
+                pack,
+                "data/minecraft/tags/worldgen/biome/is_hill.json",
+                "{\"values\":[]}",
+            );
+        }
+        write("a", "data/minecraft/worldgen/biome/new_peaks.json", "{}");
+        write("a", "data/minecraft/worldgen/biome/plains.json", "{}");
+        write(
+            "a",
+            "data/minecraft/worldgen/world_preset/normal.json",
+            "{}",
+        );
+        write(
+            "b",
+            "data/minecraft/dimension_type/overworld.json",
+            "{\"min_y\":-64,\"height\":2096}",
+        );
+        // `b` is enabled first, so `a` (enabled after it) wins.
+        std::fs::write(
+            dir.join("datapacks.json"),
+            "{\"enabled\":[\"file/b\",\"file/a\"],\"disabled\":[\"file/off\"]}",
+        )
+        .unwrap();
+        let packs = discover(&dir);
+        let enabled = enabled_ids(&dir, &packs);
+        assert_eq!(enabled, ["file/b", "file/a"]);
+        let enabled: Vec<&DataPack> = enabled
+            .iter()
+            .map(|id| packs.iter().find(|p| &p.id == id).unwrap())
+            .collect();
+        let (o, warnings) = worldgen_overrides(&enabled, |b| b == "minecraft:plains");
+        assert_eq!(
+            o.entries("noises").collect::<Vec<_>>(),
+            [("minecraft:cave", "a")]
+        );
+        assert_eq!(
+            o.entries("biomes").collect::<Vec<_>>(),
+            [("minecraft:plains", "{}")]
+        );
+        let tag_packs: Vec<&str> = o.tags("biome_tags").map(|(_, p, _)| p).collect();
+        assert_eq!(tag_packs, ["file/b", "file/a"]);
+        assert_eq!(warnings.len(), 3, "{warnings:?}");
+        assert!(warnings[0].contains("height 2096"));
+        assert!(warnings[1].contains("minecraft:new_peaks"));
+        assert!(warnings[2].contains("worldgen/world_preset"));
+        let _ = std::fs::remove_dir_all(&dir);
+    }
     use horizon_world::nbt::parse_snbt;
 
     #[test]
@@ -566,4 +806,51 @@ mod tests {
         assert_eq!(p.list_kinds(&kinds), wanted);
         let _ = std::fs::remove_dir_all(&dir);
     }
+
+    #[test]
+    fn create_world_installs_its_packs() {
+        let root = std::env::temp_dir().join(format!("hz-datapack-install-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&root);
+        let (dir, world) = (root.join("mcworld"), root.join("world"));
+        let write = |pack: &str, p: &str, t: &str| {
+            let path = dir.join(pack).join(p);
+            std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+            std::fs::write(path, t).unwrap();
+        };
+        write("fns", "pack.mcmeta", r#"{"pack":{"pack_format":121}}"#);
+        write("fns", "data/x/function/f.mcfunction", "say hi");
+        write("off", "pack.mcmeta", r#"{"pack":{"pack_format":121}}"#);
+        std::fs::create_dir_all(&dir).unwrap();
+        let mut zip = zip::ZipWriter::new(std::fs::File::create(dir.join("old.zip")).unwrap());
+        zip.start_file("pack.mcmeta", zip::write::SimpleFileOptions::default())
+            .unwrap();
+        std::io::Write::write_all(&mut zip, br#"{"pack":{"pack_format":48}}"#).unwrap();
+        zip.finish().unwrap();
+        let infos = screen_packs(&dir, &root);
+        let ids: Vec<&str> = infos.iter().map(|p| p.id.as_str()).collect();
+        assert_eq!(ids, ["file/fns", "file/off", "file/old.zip", "vanilla"]);
+        let compat: Vec<_> = infos.iter().map(|p| p.compat).collect();
+        use crate::pack_screen::Compat;
+        assert_eq!(
+            compat,
+            [
+                Compat::Compatible,
+                Compat::Compatible,
+                Compat::TooOld,
+                Compat::Compatible
+            ]
+        );
+        let selected = ["vanilla", "file/old.zip", "file/fns"].map(String::from);
+        install(&dir, &world, &selected).unwrap();
+        let packs = discover(&world);
+        let ids: Vec<&str> = packs.iter().map(|p| p.id.as_str()).collect();
+        assert_eq!(ids, ["file/fns", "file/off", "file/old.zip"]);
+        let saved: serde_json::Value =
+            serde_json::from_slice(&std::fs::read(world.join("datapacks.json")).unwrap()).unwrap();
+        assert_eq!(
+            saved,
+            serde_json::json!({"enabled": selected, "disabled": ["file/off"]})
+        );
+        let _ = std::fs::remove_dir_all(&root);
+    }
 }

crates/horizon-client-render/src/entity.wgsl

@@ -22,6 +22,7 @@ struct Globals {
     outline_params: vec4<f32>,
     // Horizon Extras' dynamic lights: camera-relative position and level (dynamic_light.rs).
     dynamic_lights: array<vec4<f32>, 16>,
+    sunrise_fan: array<vec4<f32>, 32>,
 }
 @group(0) @binding(0) var<uniform> globals: Globals;
 @group(0) @binding(1) var atlas: texture_2d<f32>;

crates/horizon-client-render/src/fog.rs

@@ -203,6 +203,13 @@ pub struct FogInputs<'a> {
     /// `BossHealthOverlay.shouldCreateWorldFog`: a boss bar with
     /// `createWorldFog` is shown (the Ender Dragon's).
     pub boss_world_fog: bool,
+    /// The camera entity is a spectator (`LavaFogEnvironment`).
+    pub spectator: bool,
+    /// The camera entity has Fire Resistance (`LavaFogEnvironment`).
+    pub fire_resistance: bool,
+    /// `GameRenderer.nightVisionScale` while Night Vision is on without
+    /// Darkness, else 0 (`FogRenderer.computeFogColor`'s brightenFactor).
+    pub night_vision: f32,
 }
 
 /// `FogRenderer.setupFog` + `computeFogColor`.
@@ -272,7 +279,11 @@ pub fn setup_fog(tables: &FogTables, state: &FogState, input: &FogInputs) -> Fog
         color[1] += (color[1] * 0.6 - color[1]) * t;
         color[2] += (color[2] * 0.6 - color[2]) * t;
     }
-    let brighten = if eye_in_water { water_vision } else { 0.0 };
+    let brighten = if eye_in_water {
+        water_vision
+    } else {
+        input.night_vision
+    };
     if color.iter().all(|&c| c != 0.0) {
         let scale = 1.0 / color[0].max(color[1]).max(color[2]);
         color = color.map(|c| c + (c * scale - c) * brighten);
@@ -288,10 +299,16 @@ pub fn setup_fog(tables: &FogTables, state: &FogState, input: &FogInputs) -> Fog
     };
     match input.fog_type {
         FogType::Lava => {
-            fog.environmental_start = 0.25;
-            fog.environmental_end = 1.0;
-            fog.sky_end = 1.0;
-            fog.cloud_end = 1.0;
+            // LavaFogEnvironment.setupFog.
+            (fog.environmental_start, fog.environmental_end) = if input.spectator {
+                (-8.0, rd * 0.5)
+            } else if input.fire_resistance {
+                (0.0, 5.0)
+            } else {
+                (0.25, 1.0)
+            };
+            fog.sky_end = fog.environmental_end;
+            fog.cloud_end = fog.environmental_end;
         }
         FogType::PowderSnow => {
             fog.environmental_start = 0.0;
@@ -362,6 +379,22 @@ pub fn setup_fog(tables: &FogTables, state: &FogState, input: &FogInputs) -> Fog
     }
     fog
 }
+/// Horizon's Fog option turned off (`horizon-graphics.txt` `fog:false`):
+/// no distance fog, in any dimension: the dimension's and biome's own fog
+/// (`visual/fog_start_distance`, `fog_end_distance`: the Nether's ends at 96
+/// blocks) and the render-distance fog. The fog of the fluid or powder snow
+/// the camera is in, blindness, darkness and a boss's world fog keep their
+/// limits. Vanilla has no such option.
+pub fn clear_distance_fog(fog: &mut FogData, input: &FogInputs) {
+    if input.fog_type == FogType::Atmospheric
+        && input.darkness.is_none()
+        && !input.boss_world_fog
+        && input.blindness.is_none()
+    {
+        (fog.render_distance_start, fog.render_distance_end) = (1e9, 2e9);
+        (fog.environmental_start, fog.environmental_end) = (1e9, 2e9);
+    }
+}
 /// `AtmosphericFogEnvironment.updateRainFogState`.
 pub fn update_rain_fog(
     state: &mut FogState,
@@ -405,6 +438,9 @@ mod tests {
             darkness: None,
             darken_world: 0.0,
             boss_world_fog: false,
+            spectator: false,
+            fire_resistance: false,
+            night_vision: 0.0,
         }
     }
     #[test]
@@ -432,6 +468,56 @@ mod tests {
         assert_eq!(water.environmental_start, -8.0);
     }
     #[test]
+    fn fog_off_clears_the_nether_fog_too() {
+        // The Nether's visual/fog_start_distance and fog_end_distance (10, 96)
+        // end before the render distance; the Fog option still clears them.
+        let nether = Sky {
+            fog_start: 10.0,
+            fog_end: 96.0,
+            ..Sky::default()
+        };
+        let tables = FogTables {
+            water_fog_end: vec![1.0],
+        };
+        let mut input = inputs(&nether);
+        input.skybox = false;
+        let mut fog = setup_fog(&tables, &FogState::default(), &input);
+        assert_eq!(fog.environmental_end, 96.0);
+        clear_distance_fog(&mut fog, &input);
+        assert!(fog.environmental_start >= 1e9 && fog.render_distance_start >= 1e9);
+    }
+    #[test]
+    fn fog_off_keeps_fluid_and_effect_fog() {
+        let sky = Sky {
+            fog_start: 10.0,
+            fog_end: 96.0,
+            ..Sky::default()
+        };
+        let tables = FogTables {
+            water_fog_end: vec![1.0],
+        };
+        let kept = |input: &FogInputs| {
+            let mut fog = setup_fog(&tables, &FogState::default(), input);
+            let before = fog;
+            clear_distance_fog(&mut fog, input);
+            fog == before
+        };
+        for fog_type in [FogType::Lava, FogType::PowderSnow, FogType::Water] {
+            let mut input = inputs(&sky);
+            input.fog_type = fog_type;
+            assert!(kept(&input), "{fog_type:?}");
+        }
+        let mut input = inputs(&sky);
+        input.blindness = Some((100, false));
+        assert!(kept(&input));
+        let mut input = inputs(&sky);
+        input.darkness = Some(0.5);
+        assert!(kept(&input));
+        let mut input = inputs(&sky);
+        input.boss_world_fog = true;
+        assert!(kept(&input));
+    }
+    #[test]
     fn boss_darkening_dims_fog_color() {
         // FogRenderer.computeFogColor: lerp toward 70/60/60% of each channel.
         let sky = Sky {

crates/horizon-client-render/src/font.rs

@@ -8,7 +8,7 @@
 //! offsets), styled drawing and StringSplitter-style line wrapping.
 use crate::{
     hud::Rect,
-    text::{Style, Text},
+    text::{Span, Style, Text, legacy_format},
     zip::Zip,
 };
 use ab_glyph::{Font as _, ScaleFont as _};
@@ -966,6 +966,83 @@ impl Font {
         }
         out
     }
+    /// `Font.split`: `StringSplitter.splitLines(text, width, Style.EMPTY)` over
+    /// the text's parts with their `§` codes in. A code styles what follows
+    /// (`§r` back to no style while measuring), and the part a line breaks in
+    /// goes on in the style at the break. Lines keep their codes for drawing.
+    pub fn split_formatted(&self, t: &Text, max_width: f32) -> Vec<Text> {
+        let max_width = max_width.max(1.0);
+        let mut parts: Vec<(Vec<char>, Style)> = t
+            .spans
+            .iter()
+            .filter(|s| !s.text.is_empty())
+            .map(|s| (s.text.chars().collect(), s.style.clone()))
+            .collect();
+        let mut flat: Vec<char> = parts.iter().flat_map(|p| p.0.iter().copied()).collect();
+        let mut out = Vec::new();
+        let mut force_new_line = false;
+        // One LineBreakFinder per line, over the parts left.
+        while let Some((at, split_style)) = self.line_break(&parts, max_width) {
+            let tail = flat[at];
+            let new_line = tail == '\n';
+            let skip = usize::from(new_line || tail == ' ');
+            force_new_line = new_line;
+            out.push(split_at(&mut parts, at, skip, &split_style));
+            flat.drain(..at + skip);
+        }
+        if !parts.is_empty() {
+            let mut rest = Text::default();
+            rest.spans = parts
+                .into_iter()
+                .map(|(text, style)| Span {
+                    text: text.into_iter().collect(),
+                    style,
+                })
+                .collect();
+            out.push(rest);
+        } else if force_new_line {
+            out.push(Text::empty());
+        }
+        out
+    }
+    /// `StringSplitter.LineBreakFinder` fed by `StringDecomposer.iterateFormatted`:
+    /// where the parts break (a character index) and the style there.
+    fn line_break(&self, parts: &[(Vec<char>, Style)], max_width: f32) -> Option<(usize, Style)> {
+        let (mut width, mut had_visible, mut last_space) = (0.0f32, false, None);
+        let mut offset = 0;
+        for (contents, part_style) in parts {
+            let mut style = part_style.clone();
+            let mut i = 0;
+            while i < contents.len() {
+                let c = contents[i];
+                if c == '§' {
+                    // A `§` that ends its part ends only that part.
+                    let Some(&code) = contents.get(i + 1) else {
+                        break;
+                    };
+                    style = legacy_format(&style, code, &Style::default());
+                    i += 2;
+                    continue;
+                }
+                let at = offset + i;
+                if c == '\n' {
+                    return Some((at, style));
+                }
+                if c == ' ' {
+                    last_space = Some((at, style.clone()));
+                }
+                let advance = self.advance(c, &style);
+                width += advance;
+                if had_visible && width > max_width {
+                    return Some(last_space.unwrap_or((at, style)));
+                }
+                had_visible |= advance != 0.0;
+                i += 1;
+            }
+            offset += contents.len();
+        }
+        None
+    }
     /// `ComponentRenderUtils.wrapComponents`: the split lines, wrapped ones
     /// indented by an unstyled space; one empty line for empty text.
     pub fn wrap_components(&self, t: &Text, max_width: i32) -> Vec<Text> {
@@ -1059,6 +1136,47 @@ impl Font {
     }
 }
 
+/// `StringSplitter.FlatComponents.splitAt`: the parts before `at` as a line,
+/// `skip` characters dropped, and the part it ends in restyled as `style`.
+fn split_at(parts: &mut Vec<(Vec<char>, Style)>, at: usize, skip: usize, style: &Style) -> Text {
+    let mut line = Text::default();
+    let mut push = |text: &[char], style: &Style| {
+        line.spans.push(Span {
+            text: text.iter().collect(),
+            style: style.clone(),
+        })
+    };
+    // Each part done is removed, so the one at hand is always the first.
+    let (mut position, mut in_skip) = (at, false);
+    while let Some((text, part_style)) = parts.first() {
+        let size = text.len();
+        if !in_skip {
+            if position > size {
+                push(text, part_style);
+                parts.remove(0);
+                position -= size;
+                continue;
+            }
+            if position > 0 {
+                push(&text[..position], part_style);
+            }
+            position += skip;
+            in_skip = true;
+        }
+        if position <= size {
+            if position == size {
+                parts.remove(0);
+            } else {
+                parts[0] = (text[position..].to_vec(), style.clone());
+            }
+            break;
+        }
+        parts.remove(0);
+        position -= size;
+    }
+    line
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -1221,6 +1339,37 @@ mod tests {
         assert!(!font.take_patches().is_empty());
     }
 
+    /// StringDecomposer.iterateFormatted: a `§` that ends a part stops that
+    /// part only; the next part is still measured and can break.
+    #[test]
+    fn a_section_sign_ending_a_part_still_breaks_the_next() {
+        let sheet = png(16, 8, |x, _| x < 2);
+        let default = br#"{"providers":[{"type":"space","advances":{" ":4}},{"type":"bitmap","file":"minecraft:font/a.png","ascent":7,"chars":["ab"]}]}"#;
+        let root = root(
+            "section-sign",
+            &[
+                ("assets/minecraft/font/default.json", default),
+                ("assets/minecraft/textures/font/a.png", &sheet),
+            ],
+        );
+        let font = load(&root);
+        let _ = std::fs::remove_dir_all(&root);
+        let mut text = Text::default();
+        text.spans = ["a§", "a a"]
+            .map(|part| Span {
+                text: part.into(),
+                style: Style::default(),
+            })
+            .into();
+        // 3 + 3 + 4 + 3 is past 12: the line breaks at the space.
+        let lines: Vec<String> = font
+            .split_formatted(&text, 12.0)
+            .iter()
+            .map(Text::plain)
+            .collect();
+        assert_eq!(lines, ["a§a", "a"]);
+    }
+
     /// A renderer rebuilt over the same font (the loading screen's handoff)
     /// makes its atlas texture from the textures alone, so the glyphs it had
     /// rasterized into the previous texture must be placed into the new one.

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

@@ -39,8 +39,9 @@ mod entity_outline;
 mod weather;
 use entity_batch::EntityBatch;
 pub use entity_batch::{
-    ENERGY_SWIRL_OVERLAY, SHADOW_OVERLAY, TRANSLUCENT_GLINT_ITEM_OVERLAY, TRANSLUCENT_ITEM_OVERLAY,
-    TRANSLUCENT_PARTICLE_OVERLAY, WATER_MASK_OVERLAY,
+    ENERGY_SWIRL_OVERLAY, SHADOW_OVERLAY, TEXT_POLYGON_OFFSET_OVERLAY,
+    TRANSLUCENT_GLINT_ITEM_OVERLAY, TRANSLUCENT_ITEM_OVERLAY, TRANSLUCENT_PARTICLE_OVERLAY,
+    WATER_MASK_OVERLAY,
 };
 
 /// Window.getAppropriateLineWidth, in framebuffer pixels.
@@ -93,6 +94,7 @@ mod page_runs;
 pub mod panorama;
 mod resident;
 mod stars;
+mod sunrise_fan;
 mod timing;
 pub mod translucency;
 pub(crate) mod upload;
@@ -188,6 +190,8 @@ struct Globals {
     outline_params: [f32; 4],
     /// Horizon Extras' dynamic lights: camera-relative position and level (`dynamic_light`).
     dynamic_lights: [[f32; 4]; crate::dynamic_light::MAX],
+    /// The sunrise fan's triangles as the sky shader tests them (`sunrise_fan::normals`).
+    sunrise_fan: [[f32; 4]; 2 * sunrise_fan::TRIANGLES],
 }
 pub type SectionKey = (i32, i32, i32);
 struct SectionGpu {
@@ -425,6 +429,7 @@ pub struct Renderer {
     lightning_pipeline: wgpu::RenderPipeline,
     lightning: lightning::Renderer,
     see_through_pipeline: wgpu::RenderPipeline,
+    text_polygon_offset_pipeline: wgpu::RenderPipeline,
     celestial_pipeline: wgpu::RenderPipeline,
     celestial_buffer: wgpu::Buffer,
     end_sky: end_sky::EndSky,
@@ -533,7 +538,7 @@ pub struct Renderer {
     block_entity_revision: u64,
     /// VisGraph face connectivity per meshed section (cave culling).
     occlusion: occlusion::Occlusion,
-    /// Resolution scale and FXAA (Horizon settings).
+    /// Resolution scale, FXAA and TAA (Horizon settings).
     world_post: world_post::Post,
     /// HDR output (Horizon setting): `Some` while the swapchain is HDR.
     hdr: Option<hdr::Hdr>,
@@ -765,8 +770,14 @@ fn mip_chain(
 /// pass is also what passes each draw's first instance to shaders reading
 /// `instance_index`, and DirectX 12 is the fallback, where working matters
 /// more than CPU time.
-fn instance_descriptor(backends: wgpu::Backends) -> wgpu::InstanceDescriptor {
+fn instance_descriptor(
+    backends: wgpu::Backends,
+    window: Option<&Arc<Window>>,
+) -> wgpu::InstanceDescriptor {
     let mut descriptor = wgpu::InstanceDescriptor::new_without_display_handle();
+    if let Some(window) = window {
+        descriptor = descriptor.with_display_handle(Box::new(WindowDisplay(window.clone())));
+    }
     descriptor.backends = backends.with_env();
     let dx12 = cfg!(windows) && descriptor.backends.contains(wgpu::Backends::DX12);
     if !cfg!(debug_assertions) && !dx12 {
@@ -776,6 +787,21 @@ fn instance_descriptor(backends: wgpu::Backends) -> wgpu::InstanceDescriptor {
     }
     descriptor.with_env()
 }
+/// The window's display connection, so the OpenGL backend creates its EGL
+/// display from the X11 or Wayland connection the window lives on. Without
+/// one, wgpu-hal falls back to `EGL_MESA_platform_surfaceless`, whose configs
+/// cannot present to a window; the backend then reports the surface as
+/// incompatible and the game has no OpenGL to fall back to (`gl not
+/// compatible with provided surface`).
+#[derive(Debug, Clone)]
+struct WindowDisplay(Arc<Window>);
+impl wgpu::rwh::HasDisplayHandle for WindowDisplay {
+    fn display_handle(
+        &self,
+    ) -> std::result::Result<wgpu::rwh::DisplayHandle<'_>, wgpu::rwh::HandleError> {
+        wgpu::rwh::HasDisplayHandle::display_handle(&*self.0)
+    }
+}
 /// The backends to open a device on, each tried in turn until one gives a
 /// device. `api` is the player's choice (`GraphicsApi::with_env` applied);
 /// `os` is `std::env::consts::OS`; `wgpu_backend`: whether `WGPU_BACKEND` is set,
@@ -853,6 +879,14 @@ fn check_layers(limits: &wgpu::Limits, layers: u32) -> Result<()> {
     }
     Ok(())
 }
+/// Whether the swapchain can take a window of `width` x `height`: each side from 1 to the
+/// device's `max_texture_dimension_2d` (`max`), else `Surface::configure` panics. 0 is a
+/// minimized window. Past `max`: Windows lets a program size a window up to 65535 pixels
+/// (`SetWindowPos`), a 984x65496 client area, when an RTX 5080 takes 32768. Vanilla's
+/// `Window.onFramebufferResize` likewise keeps the last size for one that is not positive.
+fn drawable_size(width: u32, height: u32, max: u32) -> bool {
+    (1..=max).contains(&width) && (1..=max).contains(&height)
+}
 /// The swapchain format: a non-sRGB target, because vanilla blends and tints in gamma
 /// space, and 8-bit, because wgpu gives `Rgba16Float` the linear `ExtendedSrgb` color
 /// space: the compositor would read these gamma-encoded values as linear light and wash
@@ -890,7 +924,7 @@ async fn open_device(
         if attempt > 0 {
             log::warn!("Horizon renderer: trying {name} ({})", failures.join("; "));
         }
-        let instance = wgpu::Instance::new(instance_descriptor(backends));
+        let instance = wgpu::Instance::new(instance_descriptor(backends, Some(window)));
         let surface = if offscreen {
             None
         } else {
@@ -1100,9 +1134,14 @@ impl Renderer {
         let info = adapter.get_info();
         crate::graphics::suggest_reduced_far_detail(crate::graphics::lod_capped(&info));
         let size = window.inner_size();
+        let max_side = device.limits().max_texture_dimension_2d;
         let (config, present_modes, hdr_output) = if let Some(surface) = &surface {
             let mut config = surface
-                .get_default_config(&adapter, size.width.max(1), size.height.max(1))
+                .get_default_config(
+                    &adapter,
+                    size.width.clamp(1, max_side),
+                    size.height.clamp(1, max_side),
+                )
                 .ok_or("surface has no supported configuration")?;
             let caps = surface.get_capabilities(&adapter);
             config.format = surface_format(&caps.formats, config.format);
@@ -1128,14 +1167,21 @@ impl Renderer {
                 ));
             }
             surface.configure(&device, &config);
-            (config, caps.present_modes.clone(), hdr::output(&caps))
+            let hdr_output = hdr::output(&caps);
+            if previous.is_none() {
+                log::info!(
+                    "Horizon renderer: HDR output {}",
+                    hdr_output.map_or("not offered by this display", hdr::Output::name)
+                );
+            }
+            (config, caps.present_modes.clone(), hdr_output)
         } else {
             let format = wgpu::TextureFormat::Bgra8Unorm;
             let config = wgpu::SurfaceConfiguration {
                 usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_SRC,
                 format,
-                width: size.width.max(1),
-                height: size.height.max(1),
+                width: size.width.clamp(1, max_side),
+                height: size.height.clamp(1, max_side),
                 present_mode: wgpu::PresentMode::Immediate,
                 desired_maximum_frame_latency: 2,
                 alpha_mode: wgpu::CompositeAlphaMode::Opaque,
@@ -2016,6 +2062,21 @@ impl Renderer {
             alpha_blend,
             false,
         );
+        // RenderPipelines.TEXT_POLYGON_OFFSET: a text display's text and
+        // background win against the surface they lie on (bias 1, 10).
+        let text_polygon_offset_pipeline = entity_pipeline(
+            "Polygon offset text",
+            None,
+            true,
+            wgpu::CompareFunction::GreaterEqual,
+            wgpu::DepthBiasState {
+                constant: 10,
+                slope_scale: 1.0,
+                clamp: 0.0,
+            },
+            alpha_blend,
+            false,
+        );
         let entity_pipeline = entity_pipeline(
             "Entities",
             None,
@@ -2573,6 +2634,7 @@ impl Renderer {
             lightning_pipeline,
             lightning: lightning::Renderer::new(),
             see_through_pipeline,
+            text_polygon_offset_pipeline,
             celestial_pipeline,
             celestial_buffer,
             end_sky: end_sky::EndSky::default(),
@@ -2661,7 +2723,7 @@ impl Renderer {
             hud,
             menu_blur: None,
             info,
-            suspended: size.width == 0 || size.height == 0,
+            suspended: !drawable_size(size.width, size.height, max_side),
             drawn_sections: 0,
             section_draws: 0,
             section_draw_calls: 0,
@@ -2821,8 +2883,11 @@ impl Renderer {
             );
         }
     }
+    /// Follows the window to `width` x `height`. A size the swapchain can't take
+    /// ([`drawable_size`]) keeps the last one and draws nothing until the next.
     pub fn resize(&mut self, width: u32, height: u32) {
-        self.suspended = width == 0 || height == 0;
+        let max = self.device.limits().max_texture_dimension_2d;
+        self.suspended = !drawable_size(width, height, max);
         if self.suspended {
             return;
         }
@@ -3206,6 +3271,19 @@ impl Renderer {
         }
         config
     }
+    /// The F3 screen's HDR line while the setting is on: the swapchain HDR presents to with
+    /// its paper white and peak, or that the surface offers none.
+    pub fn hdr_line(&self) -> String {
+        match &self.hdr {
+            Some(hdr) => format!(
+                "HDR: {}, {}/{} nits",
+                hdr.output.name(),
+                hdr.paper_white.round(),
+                hdr.peak.round()
+            ),
+            None => "HDR: not offered by this display".into(),
+        }
+    }
     /// HDR output (Horizon setting): HDR10 or scRGB at `paper_white` nits, the world's
     /// highlights expanded up to `peak` nits. Off where the surface can't present it.
     pub fn set_hdr(&mut self, on: bool, paper_white: f32, peak: f32, marker: &std::path::Path) {
@@ -3222,6 +3300,14 @@ impl Renderer {
             let format = self.config.format.remove_srgb_suffix();
             self.hdr = output.map(|output| hdr::Hdr::new(&self.device, format, output));
             self.configure_surface();
+            match output {
+                Some(output) => log::info!(
+                    "Horizon renderer: HDR on: {} ({:?}), {paper_white}/{peak} nits",
+                    output.name(),
+                    output.format()
+                ),
+                None => log::info!("Horizon renderer: HDR off"),
+            }
         }
         if let Some(hdr) = &mut self.hdr
             && (hdr.paper_white, hdr.peak) != (paper_white, peak)
@@ -3231,9 +3317,12 @@ impl Renderer {
             self.send_hdr_metadata();
         }
     }
-    pub fn set_world_post(&mut self, scale: f32, antialias: bool) {
+    /// `upscale`: output pixels per rendered pixel, for TAA to rebuild (1: native).
+    pub fn set_world_post(&mut self, scale: f32, antialias: bool, taa: bool, upscale: f32) {
         self.world_post.scale = scale.clamp(0.25, 2.0);
-        self.world_post.antialias = antialias;
+        self.world_post.antialias = antialias && !taa;
+        self.world_post.taa = taa;
+        self.world_post.upscale = if taa { upscale.clamp(1.0, 4.0) } else { 1.0 };
     }
     /// Runs `post` over the world from now on (`None`: no pack), for the dimension `dimension`;
     /// `block_ids` gives each block sprite layer's `mc_Entity` (id, fluid) pair.
@@ -3615,6 +3704,16 @@ impl Renderer {
             frame.boss_darken,
         );
         let view_proj = self.view_projection(frame);
+        // TAA runs where the world post pass does, not under a shader pack's own.
+        let taa = !frame.title
+            && self.pack_post.as_ref().is_none_or(|p| p.1.is_none())
+            && self.native.as_ref().is_none_or(|n| n.post.is_none());
+        let jittered = self.world_post.jitter(
+            [self.config.width, self.config.height],
+            taa,
+            view_proj,
+            frame.camera,
+        ) * view_proj;
         if frame.title {
             self.panorama.prepare(
                 &self.queue,
@@ -3666,7 +3765,7 @@ impl Renderer {
             )
         };
         let globals = Globals {
-            view_proj: view_proj.to_cols_array_2d(),
+            view_proj: jittered.to_cols_array_2d(),
             fog_color,
             fog,
             sky_color: [
@@ -3706,6 +3805,7 @@ impl Renderer {
                 }
                 lights
             },
+            sunrise_fan: sunrise_fan::normals(frame.sky.sunrise_color[3], sun),
         };
         self.uploads
             .buffer(&mut encoder, &self.globals, 0, bytemuck::bytes_of(&globals));
@@ -4208,6 +4308,7 @@ impl Renderer {
         }
         let [
             entity_quads,
+            text_quads,
             crumbling_quads,
             translucent_crumbling_quads,
             water_mask_quads,
@@ -4220,6 +4321,7 @@ impl Renderer {
             .update(entities, frame.additive, frame.hand, frame.see_through);
         let weather_quads = frame.weather.len() as u32 / 4;
         let world_quads = entity_quads
+            + text_quads
             + crumbling_quads
             + translucent_crumbling_quads
             + water_mask_quads
@@ -4298,7 +4400,7 @@ impl Renderer {
             self.stars.prepare(
                 &mut self.uploads,
                 &mut encoder,
-                view_proj * rotation,
+                jittered * rotation,
                 brightness,
             );
         }
@@ -4471,6 +4573,8 @@ impl Renderer {
                 .flatten();
         }
         let pack_reads_world = pack_post || native_post;
+        // Phase 2 of occlusion culling draws over the depth, and a shader pack or TAA reads it.
+        let keep_depth = pack_reads_world || (taa && self.world_post.taa);
         // The pack's program reads the vertices this frame's draws bind.
         let pack_draws_terrain = pack_terrain && flat_frame == self.pack_terrain_flat;
         // The shadow camera's lists, drawn by the pack's shadow programs.
@@ -4622,8 +4726,7 @@ impl Renderer {
                     view: world_depth,
                     depth_ops: Some(wgpu::Operations {
                         load: wgpu::LoadOp::Clear(0.0),
-                        // Phase 2 of occlusion culling draws over it; a shader pack reads it.
-                        store: if cull.is_some() || pack_reads_world {
+                        store: if cull.is_some() || keep_depth {
                             wgpu::StoreOp::Store
                         } else {
                             wgpu::StoreOp::Discard
@@ -4698,7 +4801,7 @@ impl Renderer {
                                 &mut encoder,
                                 world_view,
                                 world_depth,
-                                pack_reads_world,
+                                keep_depth,
                             );
                             pass.set_bind_group(0, &self.group, &[]);
                             pack_frame(&mut pass);
@@ -4728,7 +4831,7 @@ impl Renderer {
                                 &mut encoder,
                                 world_view,
                                 world_depth,
-                                pack_reads_world,
+                                keep_depth,
                             );
                             pass.set_bind_group(0, &self.group, &[]);
                             pack_frame(&mut pass);
@@ -4757,6 +4860,13 @@ impl Renderer {
                 pass.draw_indexed(0..entity_quads * 6, 0, 0..1);
                 pass.set_bind_group(0, &self.group, &[]);
             }
+            if text_quads > 0 {
+                pass.set_pipeline(&self.text_polygon_offset_pipeline);
+                pass.set_bind_group(0, &self.entity_group, &[]);
+                pass.set_vertex_buffer(0, self.entity_buffer.slice(..));
+                pass.draw_indexed(0..text_quads * 6, (entity_quads * 4) as i32, 0..1);
+                pass.set_bind_group(0, &self.group, &[]);
+            }
             if translucent_item_quads > 0 {
                 pass.set_pipeline(&self.translucent_item_pipeline);
                 pass.set_bind_group(0, &self.entity_group, &[]);
@@ -4776,7 +4886,11 @@ impl Renderer {
                 pass.set_pipeline(&self.crumbling_pipeline);
                 pass.set_bind_group(0, &self.entity_group, &[]);
                 pass.set_vertex_buffer(0, self.entity_buffer.slice(..));
-                pass.draw_indexed(0..crumbling_quads * 6, (entity_quads * 4) as i32, 0..1);
+                pass.draw_indexed(
+                    0..crumbling_quads * 6,
+                    ((entity_quads + text_quads) * 4) as i32,
+                    0..1,
+                );
                 pass.set_bind_group(0, &self.group, &[]);
             }
             if shadow_quads > 0 {
@@ -4802,7 +4916,8 @@ impl Renderer {
                 pass.set_vertex_buffer(0, self.entity_buffer.slice(..));
                 pass.draw_indexed(
                     0..water_mask_quads * 6,
-                    ((entity_quads + crumbling_quads + translucent_crumbling_quads) * 4) as i32,
+                    ((entity_quads + text_quads + crumbling_quads + translucent_crumbling_quads)
+                        * 4) as i32,
                     0..1,
                 );
                 pass.set_bind_group(0, &self.group, &[]);
@@ -4820,6 +4935,7 @@ impl Renderer {
                 pass.draw_indexed(
                     0..swirl_quads * 6,
                     ((entity_quads
+                        + text_quads
                         + crumbling_quads
                         + translucent_crumbling_quads
                         + water_mask_quads)
@@ -4913,7 +5029,7 @@ impl Renderer {
                 pass.set_vertex_buffer(0, self.entity_buffer.slice(..));
                 pass.draw_indexed(
                     0..translucent_crumbling_quads * 6,
-                    ((entity_quads + crumbling_quads) * 4) as i32,
+                    ((entity_quads + text_quads + crumbling_quads) * 4) as i32,
                     0..1,
                 );
             }
@@ -5041,7 +5157,8 @@ impl Renderer {
                 native.timing.as_mut(),
             );
         } else if scaled.is_some() {
-            self.world_post.finish(&mut encoder, &view_target);
+            self.world_post
+                .finish(&self.queue, &mut encoder, &view_target);
         }
         if let Some(hdr) = &self.hdr {
             hdr.keep_world(&mut encoder);
@@ -5452,6 +5569,23 @@ fn frustum(m: Mat4) -> [Vec4; 6] {
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    fn drawable_size_skips_minimized_and_oversized_windows() {
+        use super::drawable_size;
+        assert!(drawable_size(1280, 720, 8192));
+        assert!(drawable_size(1, 1, 8192));
+        assert!(drawable_size(8192, 8192, 8192));
+        // Minimized.
+        assert!(!drawable_size(0, 720, 8192));
+        assert!(!drawable_size(1280, 0, 8192));
+        assert!(!drawable_size(0, 0, 8192));
+        // One past the device's largest texture.
+        assert!(!drawable_size(8193, 720, 8192));
+        assert!(!drawable_size(1280, 8193, 8192));
+        // The crash: a window `SetWindowPos` made 65535 pixels tall, on an RTX 5080 (32768).
+        assert!(!drawable_size(984, 65496, 32768));
+        assert!(!drawable_size(984, u32::MAX, 32768));
+    }
     #[test]
     fn surface_is_8_bit_and_not_srgb() {
         use super::surface_format;
@@ -5516,6 +5650,7 @@ mod tests {
             (11, 2),
             (15, 10),
             (7, 3),
+            (35, 11),
             (4, 4),
             (12, 7),
         ]
@@ -5525,7 +5660,7 @@ mod tests {
         let mut batch = super::EntityBatch::default();
         let counts = batch.update(&entities, &quad(3, 5), &quad(0, 6), &quad(0, 8));
         let vertices = &batch.combined;
-        assert_eq!(counts, [4, 1, 1, 0, 0, 1, 1, 0]);
+        assert_eq!(counts, [4, 1, 1, 1, 0, 0, 1, 1, 0]);
         assert_eq!(
             vertices
                 .as_chunks::<4>()
@@ -5533,7 +5668,7 @@ mod tests {
                 .iter()
                 .map(|q| q[0].light)
                 .collect::<Vec<_>>(),
-            [0, 1, 3, 4, 2, 7, 9, 10, 5, 6, 8]
+            [0, 1, 3, 4, 11, 2, 7, 9, 10, 5, 6, 8]
         );
     }
     #[test]
@@ -5704,7 +5839,7 @@ mod tests {
     #[test]
     fn indirect_draws_are_validated_only_in_debug_builds_and_on_directx_12() {
         let validated = |backends| {
-            super::instance_descriptor(backends)
+            super::instance_descriptor(backends, None)
                 .flags
                 .contains(wgpu::InstanceFlags::VALIDATION_INDIRECT_CALL)
         };

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

@@ -103,10 +103,11 @@ impl SpriteAnimator {
         let mut counts: Vec<usize> = Vec::new();
         let mut sprites = Vec::with_capacity(animations.len());
         for animation in animations {
-            let chains: Vec<_> = (0..animation.frame_count())
-                .map(|frame| source_chain(animation.pixels(frame), size, settings, animation.layer))
+            let pixels: Vec<_> = (0..animation.frame_count())
+                .map(|frame| animation.pixels(frame))
                 .collect();
-            let bytes: u64 = chains.iter().map(|(chain, _)| chain.len() as u64).sum();
+            let (chains, edge) = source_chains(&pixels, size, settings, animation.layer);
+            let bytes: u64 = chains.iter().map(|chain| chain.len() as u64).sum();
             if bytes > limit {
                 log::warn!(
                     "Horizon: layer {}'s animation ({bytes} bytes) does not fit in a storage buffer; it stays still",
@@ -124,7 +125,7 @@ impl SpriteAnimator {
             let data = &mut frames[buffer];
             let offsets = chains
                 .iter()
-                .map(|(chain, _)| {
+                .map(|chain| {
                     let offset = (data.len() / 4) as u32;
                     data.extend_from_slice(chain);
                     offset
@@ -142,7 +143,7 @@ impl SpriteAnimator {
                 shown: None,
                 layer: animation.layer % split,
                 frames: offsets,
-                edge: chains[0].1,
+                edge,
                 group,
             });
         }
@@ -424,15 +425,63 @@ fn mix_level(frames: &[u8], [_, current, next, millis, edge]: [u32; 5], width: u
 /// array's size from its own size's chain, its first level repeated into the
 /// larger levels: that chain, which the shader repeats. Any other sprite: its
 /// chain at the array's size.
+#[cfg(test)]
 fn source_chain(pixels: &[u8], size: u32, settings: &[Settings], layer: u32) -> (Vec<u8>, u32) {
-    let native = settings.get(layer as usize).map_or(0, |s| s.native_size);
-    let edge = if native.is_power_of_two() && native < size {
-        native
+    let (mut chains, edge) = source_chains(&[pixels], size, settings, layer);
+    (chains.swap_remove(0), edge)
+}
+
+/// Every frame's chain, laid out as one frame's `source_chain`, but mipmapped as
+/// vanilla's `SpriteContents.increaseMipLevel` does: over the whole animation
+/// sheet (the frames stacked), so `solidify` and the alpha-to-coverage scale
+/// of each level are the sheet's, not each frame's. A frame alone has a
+/// single texel square at its 2x2 level, and its coverage scale could round
+/// a whole far frame transparent (kelp blinking out at distance).
+fn source_chains(
+    frames: &[&[u8]],
+    size: u32,
+    settings: &[Settings],
+    layer: u32,
+) -> (Vec<Vec<u8>>, u32) {
+    let s = settings.get(layer as usize).copied().unwrap_or_default();
+    let edge = if s.native_size.is_power_of_two() && s.native_size < size {
+        s.native_size
     } else {
         size
     };
-    let frame = crate::sprites::resample(pixels, size, edge);
-    (super::mip_chain(&frame, edge, settings, layer, 1).0, edge)
+    let mut sheet = crate::mipmap::Image {
+        width: edge,
+        height: edge * frames.len() as u32,
+        pixels: Vec::with_capacity((edge * edge) as usize * frames.len()),
+    };
+    for frame in frames {
+        let frame = crate::sprites::resample(frame, size, edge);
+        sheet.pixels.extend_from_slice(frame.as_chunks::<4>().0);
+    }
+    let has_transparent = s.has_transparent || sheet.pixels.iter().any(|p| p[3] == 0);
+    let levels = crate::mipmap::generate(
+        sheet,
+        edge.trailing_zeros(),
+        Settings {
+            has_transparent,
+            ..s
+        },
+    );
+    let chains = (0..frames.len())
+        .map(|frame| {
+            let mut chain = Vec::new();
+            for level in &levels {
+                let texels = (level.width * level.width) as usize;
+                chain.extend(
+                    level.pixels[frame * texels..(frame + 1) * texels]
+                        .iter()
+                        .flatten(),
+                );
+            }
+            chain
+        })
+        .collect();
+    (chains, edge)
 }
 
 #[cfg(test)]
@@ -572,6 +621,63 @@ mod tests {
         }
     }
 
+    #[test]
+    fn kelp_frames_share_the_sheet_mips() {
+        let root = std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
+            .join("../../.local/horizon-client")
+            .join(horizon_core::VANILLA_VERSION);
+        if !root
+            .join("assets/minecraft/textures/block/kelp.png")
+            .exists()
+        {
+            return;
+        }
+        let mut sprites = crate::sprites::Sprites::default();
+        for name in ["kelp", "kelp_plant", "seagrass", "tall_seagrass_top"] {
+            sprites
+                .insert(&root, &format!("minecraft:block/{name}"))
+                .unwrap();
+        }
+        sprites.finish();
+        // A level drawn nowhere: no texel passes the cutout's alpha test.
+        let blank = |chain: &[u8], edge: u32| {
+            let mut start = 0;
+            let mut level = edge;
+            let mut blank = Vec::new();
+            while level > 0 {
+                let bytes = (level * level * 4) as usize;
+                let texels = &chain[start..start + bytes];
+                blank.push(texels.as_chunks::<4>().0.iter().all(|p| p[3] < 128));
+                start += bytes;
+                level >>= 1;
+            }
+            blank
+        };
+        let mut blinked = 0;
+        for animation in &sprites.animations {
+            let size = sprites.size;
+            let pixels: Vec<_> = (0..animation.frame_count())
+                .map(|f| animation.pixels(f))
+                .collect();
+            let (chains, edge) = source_chains(&pixels, size, &sprites.mips, animation.layer);
+            for (frame, chain) in chains.iter().enumerate() {
+                // The 1x1 level has no texel square to measure coverage on
+                // (vanilla leaves it unscaled); every larger level shows.
+                let levels = blank(chain, edge);
+                assert!(
+                    !levels[..levels.len() - 1].contains(&true),
+                    "layer {} frame {frame}: {levels:?}",
+                    animation.layer
+                );
+                let (alone, _) = source_chain(pixels[frame], size, &sprites.mips, animation.layer);
+                let alone = blank(&alone, edge);
+                blinked += usize::from(alone[..alone.len() - 1].contains(&true));
+            }
+        }
+        // Mipmapped frame by frame, some kelp frames vanished at the 2x2 level.
+        assert!(blinked > 0);
+    }
+
     #[test]
     fn rounding_matches_f32_mix_but_for_exact_halves() {
         // The CPU blend this replaced: f32 mix, then rounded. They differ
@@ -730,8 +836,11 @@ mod tests {
             queue.submit([encoder.finish()]);
             for animation in &animations {
                 let blend = animation.blend(tick);
-                let chain = |f| source_chain(animation.pixels(f), size, &mips, animation.layer);
-                let ((current, edge), (next, _)) = (chain(blend.frame), chain(blend.next));
+                let pixels: Vec<_> = (0..animation.frame_count())
+                    .map(|f| animation.pixels(f))
+                    .collect();
+                let (chains, edge) = source_chains(&pixels, size, &mips, animation.layer);
+                let (current, next) = (&chains[blend.frame], &chains[blend.next]);
                 let layers = read_back(
                     &device,
                     &queue,
@@ -739,7 +848,7 @@ mod tests {
                 );
                 assert_eq!(
                     layers[(animation.layer % split) as usize],
-                    reference(&current, &next, blend.millis, edge, size),
+                    reference(current, next, blend.millis, edge, size),
                     "layer {} at tick {tick}",
                     animation.layer
                 );

crates/horizon-client-render/src/gfx/entity_batch.rs

@@ -2,13 +2,14 @@
 use super::Vertex;
 
 /// Entity materials by a quad's overlay (`Vertex::layer`), in draw order:
-/// ordinary entities, breaking cracks (11), translucent breaking cracks (12),
-/// the boat water mask (13, `RenderPipelines.WATER_MASK`), energy swirls
-/// (34, `RenderPipelines.ENERGY_SWIRL`), entity shadows (14,
+/// ordinary entities, world text drawn with a depth bias (35,
+/// `RenderPipelines.TEXT_POLYGON_OFFSET`), breaking cracks (11), translucent
+/// breaking cracks (12), the boat water mask (13, `RenderPipelines.WATER_MASK`),
+/// energy swirls (34, `RenderPipelines.ENERGY_SWIRL`), entity shadows (14,
 /// `RenderPipelines.ENTITY_SHADOW`), translucent-layer particles (15, drawn
 /// after translucent terrain: `SubmitNodeCollection.submitQuadParticleGroup`)
 /// and translucent item quads (32, drawn without depth writes).
-const MATERIALS: usize = 8;
+const MATERIALS: usize = 9;
 /// The overlay of depth-only quads that hide water (`RenderTypes.waterMask`).
 pub const WATER_MASK_OVERLAY: u32 = 13;
 /// The overlay of energy swirl quads (`RenderTypes.energySwirl`: the charged creeper's and the
@@ -24,17 +25,21 @@ pub const TRANSLUCENT_PARTICLE_OVERLAY: u32 = 15;
 pub const TRANSLUCENT_ITEM_OVERLAY: u32 = 32;
 /// A translucent item with an enchantment glint.
 pub const TRANSLUCENT_GLINT_ITEM_OVERLAY: u32 = 33;
+/// The overlay of text in `Font.DisplayMode.POLYGON_OFFSET` (text displays):
+/// drawn like an ordinary entity, pulled toward the camera.
+pub const TEXT_POLYGON_OFFSET_OVERLAY: u32 = 35;
 
 /// The material of a quad by its overlay (`MATERIALS` order).
 fn material(layer: u32) -> usize {
     match layer {
-        11 => 1,
-        12 => 2,
-        WATER_MASK_OVERLAY => 3,
-        ENERGY_SWIRL_OVERLAY => 4,
-        SHADOW_OVERLAY => 5,
-        TRANSLUCENT_PARTICLE_OVERLAY => 6,
-        TRANSLUCENT_ITEM_OVERLAY | TRANSLUCENT_GLINT_ITEM_OVERLAY => 7,
+        TEXT_POLYGON_OFFSET_OVERLAY => 1,
+        11 => 2,
+        12 => 3,
+        WATER_MASK_OVERLAY => 4,
+        ENERGY_SWIRL_OVERLAY => 5,
+        SHADOW_OVERLAY => 6,
+        TRANSLUCENT_PARTICLE_OVERLAY => 7,
+        TRANSLUCENT_ITEM_OVERLAY | TRANSLUCENT_GLINT_ITEM_OVERLAY => 8,
         _ => 0,
     }
 }
@@ -102,9 +107,10 @@ mod tests {
     ) -> (Vec<Vertex>, [u32; MATERIALS]) {
         let mut combined = Vec::with_capacity(entities.len() + additive.len() + hand.len());
         let mut counts = [0; MATERIALS];
-        for (i, layer) in [0, 11, 12, 13, 34, 14, 15].into_iter().enumerate() {
+        for (i, layer) in [0, 35, 11, 12, 13, 34, 14, 15].into_iter().enumerate() {
             for quad in entities.as_chunks::<4>().0 {
                 let material = match quad[0].layer {
+                    35 => 35,
                     11 => 11,
                     12 => 12,
                     13 => 13,
@@ -130,7 +136,7 @@ mod tests {
                 pos: [index as f32, 2.0, 3.0],
                 uv: [index as f32, 5.0],
                 layer: if mixed {
-                    [7, 11, 14, 12, 4, 13, 15, 0][index / 4 % 8]
+                    [7, 11, 14, 35, 12, 4, 13, 15, 0][index / 4 % 9]
                 } else {
                     0
                 },

crates/horizon-client-render/src/gfx/hdr.rs

@@ -14,6 +14,12 @@ pub enum Output {
 }
 
 impl Output {
+    pub fn name(self) -> &'static str {
+        match self {
+            Self::Pq => "HDR10 (PQ)",
+            Self::ScRgb => "scRGB",
+        }
+    }
     pub fn format(self) -> wgpu::TextureFormat {
         match self {
             Self::Pq => wgpu::TextureFormat::Rgb10a2Unorm,

crates/horizon-client-render/src/gfx/sunrise_fan.rs

@@ -0,0 +1,131 @@
+//! The sunrise/sunset fan (`SkyRenderer.renderSunriseAndSunset`) as the sky
+//! shader tests it. The fan's 16 triangles depend only on the sunrise alpha
+//! and the horizon the sun is on, so their vertices are built here once a
+//! frame instead of in every sky pixel (#3143: with the per-pixel build, four
+//! `sin`/`cos` per triangle, the sky pass took 10.2 ms at dawn at 1080p on an
+//! Intel UHD 730 against 0.6 ms by day; now 1.8 ms).
+//!
+//! Möller-Trumbore from the camera reduces to triple products: with apex A
+//! and rim vertices r0, r1, a ray d hits at barycentrics proportional to
+//! (`[d, r0, r1]`, `[A, d, r1]`, `[A, r0, d]`), each a dot of d with a
+//! constant normal, and their sum S is the negated determinant. A hit needs
+//! S on the side of `[A, r0, r1]`, so only the triangles whose rim normals'
+//! dots change sign there are tested in full.
+use glam::Vec3;
+
+pub const TRIANGLES: usize = 16;
+
+/// Per triangle: xyz `r0 × r1` (its dot with a ray is the apex's weight
+/// times S), w `[A, r0, r1]` (its sign is S's where the hit lies ahead).
+/// Then per rim vertex: xyz `r × A`.
+pub fn normals(alpha: f32, sun: Vec3) -> [[f32; 4]; 2 * TRIANGLES] {
+    let (apex, rim) = vertices(alpha, sun);
+    let mut out = [[0.0; 4]; 2 * TRIANGLES];
+    for i in 0..TRIANGLES {
+        let (r0, r1) = (rim[i], rim[(i + 1) % TRIANGLES]);
+        out[i] = r0.cross(r1).extend(apex.dot(r0.cross(r1))).to_array();
+        out[TRIANGLES + i] = r0.cross(apex).extend(0.0).to_array();
+    }
+    out
+}
+
+/// The fan's apex and rim in camera space, as vanilla builds them: the
+/// fan turned to the horizon the sun sets on (or rises from), its rim
+/// tilted by the alpha.
+fn vertices(alpha: f32, sun: Vec3) -> (Vec3, [Vec3; TRIANGLES]) {
+    // sin(sunAngle) < 0 flips the fan to the other horizon; sun.z = -sin(sunAngle).
+    let flip = if -sun.z < 0.0 { 180f32 } else { 0.0 };
+    let (s, c) = (flip + 90.0).to_radians().sin_cos();
+    let rotate_x90 = |v: Vec3| Vec3::new(v.x, -v.z, v.y);
+    let apex = rotate_x90(Vec3::new(-100.0 * s, 100.0 * c, 0.0));
+    let rim = std::array::from_fn(|i| {
+        let a = i as f32 * std::f32::consts::TAU / TRIANGLES as f32;
+        let l = Vec3::new(a.sin() * 120.0, a.cos() * 120.0, -a.cos() * 40.0 * alpha);
+        rotate_x90(Vec3::new(l.x * c - l.y * s, l.x * s + l.y * c, l.z))
+    });
+    (apex, rim)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// terrain.wgsl's `sunrise_weight` over the normals.
+    fn weight(normals: &[[f32; 4]; 2 * TRIANGLES], d: Vec3) -> f32 {
+        let n = |i: usize| Vec3::from_slice(&normals[i][..3]);
+        let mut best = 0.0f32;
+        let mut k0 = d.dot(n(TRIANGLES));
+        for i in 0..TRIANGLES {
+            let k1 = d.dot(n(TRIANGLES + (i + 1) % TRIANGLES));
+            let w = normals[i][3];
+            if k0 * w <= 0.0 && k1 * w >= 0.0 {
+                let apex = d.dot(n(i));
+                let s = apex + k1 - k0;
+                if s.abs() >= 1e-6
+                    && s * w > 0.0
+                    && apex * s >= 0.0
+                    && k1 * s >= 0.0
+                    && k0 * s <= 0.0
+                {
+                    best = best.max(apex / s);
+                }
+            }
+            k0 = k1;
+        }
+        best
+    }
+
+    /// The shader's former per-pixel Möller-Trumbore over the same vertices.
+    fn reference(alpha: f32, sun: Vec3, d: Vec3) -> f32 {
+        let (apex, rim) = vertices(alpha, sun);
+        let mut best = 0.0f32;
+        for i in 0..TRIANGLES {
+            let e1 = rim[i] - apex;
+            let e2 = rim[(i + 1) % TRIANGLES] - apex;
+            let pv = d.cross(e2);
+            let det = e1.dot(pv);
+            if det.abs() < 1e-6 {
+                continue;
+            }
+            let tv = -apex;
+            let u = tv.dot(pv) / det;
+            let qv = tv.cross(e1);
+            let v = d.dot(qv) / det;
+            let t = e2.dot(qv) / det;
+            if u >= 0.0 && v >= 0.0 && u + v <= 1.0 && t > 0.0 {
+                best = best.max(1.0 - u - v);
+            }
+        }
+        best
+    }
+
+    #[test]
+    fn normals_weigh_every_ray_as_the_per_pixel_fan_did() {
+        let mut hits = 0;
+        for (alpha, sun_z) in [(1.0f32, -0.2f32), (0.6, 0.3), (0.05, -0.9), (0.9, 0.05)] {
+            let sun = Vec3::new(0.0, (1.0 - sun_z * sun_z).sqrt(), sun_z);
+            let normals = normals(alpha, sun);
+            for yaw in 0..180 {
+                for pitch in -45..=45 {
+                    let (yaw, pitch) = (
+                        (yaw as f32 * 2.0).to_radians(),
+                        (pitch as f32 * 2.0).to_radians(),
+                    );
+                    let d = Vec3::new(
+                        yaw.cos() * pitch.cos(),
+                        pitch.sin(),
+                        yaw.sin() * pitch.cos(),
+                    );
+                    let (got, want) = (weight(&normals, d), reference(alpha, sun, d));
+                    assert!(
+                        (got - want).abs() < 1e-4,
+                        "{alpha} {sun_z} {d}: {got} vs {want}"
+                    );
+                    hits += usize::from(want > 0.0);
+                }
+            }
+        }
+        // The fan covers part of the sky, not none of it.
+        assert!(hits > 1000, "{hits}");
+    }
+}

crates/horizon-client-render/src/gfx/world_post.rs

@@ -0,0 +1,488 @@
+//! Resolution scale, FXAA and TAA (Horizon settings): the world renders into its
+//! own target at the scaled size, then one full-screen pass copies or
+//! anti-aliases it onto the screen, under the hand and HUD. With none on,
+//! the world renders straight to the screen.
+//!
+//! TAA jitters the world's projection by a sub-pixel offset each frame and blends
+//! the frame into a history reprojected through the depth buffer: its motion
+//! vectors are the camera's, so what moves on its own leans on the neighbourhood
+//! clamp alone.
+
+use glam::{DMat4, DVec3, Mat4, Vec2};
+
+/// The TAA history format: 8 bits would band as frames accumulate.
+const HISTORY_FORMAT: wgpu::TextureFormat = wgpu::TextureFormat::Rgba16Float;
+
+struct WorldTarget {
+    size: [u32; 2],
+    color: wgpu::TextureView,
+    depth: wgpu::TextureView,
+    group: wgpu::BindGroup,
+    taa: Option<History>,
+}
+
+/// TAA's two history textures at the output size (the world's, times the upscale), written
+/// in turn: `resolve[i]` writes `history[i]` from the world and `history[1 - i]`; `show[i]`
+/// copies `history[i]` to the screen.
+struct History {
+    size: [u32; 2],
+    history: [wgpu::TextureView; 2],
+    resolve: [wgpu::BindGroup; 2],
+    show: [wgpu::BindGroup; 2],
+}
+
+/// `world_post.wgsl`'s `Taa`.
+#[repr(C)]
+#[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
+struct TaaUniform {
+    /// This frame's unjittered clip space to the previous frame's.
+    reproject: [[f32; 4]; 4],
+    /// xy: this frame's jitter in clip space; z: 1 when the history is unusable.
+    jitter: [f32; 4],
+}
+
+pub struct Post {
+    layout: wgpu::BindGroupLayout,
+    sampler: wgpu::Sampler,
+    copy: wgpu::RenderPipeline,
+    fxaa: wgpu::RenderPipeline,
+    format: wgpu::TextureFormat,
+    /// World resolution relative to the window (0.5..=2.0).
+    pub scale: f32,
+    pub antialias: bool,
+    pub taa: bool,
+    /// Output pixels per rendered pixel while TAA is on (1: native): the world renders
+    /// this much smaller and TAA rebuilds it at the resolution scale's size.
+    pub upscale: f32,
+    /// TAA runs this frame (`jitter`): not on the title screen or under a shader pack.
+    taa_on: bool,
+    target: Option<WorldTarget>,
+    taa_layout: wgpu::BindGroupLayout,
+    taa_pipeline: wgpu::RenderPipeline,
+    taa_uniform: wgpu::Buffer,
+    /// Frames jittered so far (the Halton index), and which history the next resolve writes.
+    taa_frame: u32,
+    /// The last TAA frame's unjittered `view_proj` and camera, `None` once a frame ran without it.
+    taa_previous: Option<(DMat4, DVec3)>,
+    taa_this_frame: TaaUniform,
+}
+
+impl Post {
+    pub fn new(device: &wgpu::Device, format: wgpu::TextureFormat) -> Self {
+        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+            label: Some("Horizon post"),
+            source: wgpu::ShaderSource::Wgsl(include_str!("../world_post.wgsl").into()),
+        });
+        let layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+            label: Some("Horizon post bindings"),
+            entries: &[
+                wgpu::BindGroupLayoutEntry {
+                    binding: 0,
+                    visibility: wgpu::ShaderStages::FRAGMENT,
+                    ty: wgpu::BindingType::Texture {
+                        sample_type: wgpu::TextureSampleType::Float { filterable: true },
+                        view_dimension: wgpu::TextureViewDimension::D2,
+                        multisampled: false,
+                    },
+                    count: None,
+                },
+                wgpu::BindGroupLayoutEntry {
+                    binding: 1,
+                    visibility: wgpu::ShaderStages::FRAGMENT,
+                    ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
+                    count: None,
+                },
+            ],
+        });
+        let texture = |binding, sample_type| wgpu::BindGroupLayoutEntry {
+            binding,
+            visibility: wgpu::ShaderStages::FRAGMENT,
+            ty: wgpu::BindingType::Texture {
+                sample_type,
+                view_dimension: wgpu::TextureViewDimension::D2,
+                multisampled: false,
+            },
+            count: None,
+        };
+        let float = wgpu::TextureSampleType::Float { filterable: true };
+        let taa_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+            label: Some("Horizon TAA bindings"),
+            entries: &[
+                texture(0, float),
+                wgpu::BindGroupLayoutEntry {
+                    binding: 1,
+                    visibility: wgpu::ShaderStages::FRAGMENT,
+                    ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
+                    count: None,
+                },
+                texture(2, float),
+                texture(3, wgpu::TextureSampleType::Depth),
+                wgpu::BindGroupLayoutEntry {
+                    binding: 4,
+                    visibility: wgpu::ShaderStages::FRAGMENT,
+                    ty: wgpu::BindingType::Buffer {
+                        ty: wgpu::BufferBindingType::Uniform,
+                        has_dynamic_offset: false,
+                        min_binding_size: None,
+                    },
+                    count: None,
+                },
+            ],
+        });
+        let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+            label: Some("Horizon post"),
+            bind_group_layouts: &[Some(&layout)],
+            ..Default::default()
+        });
+        let taa_pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+            label: Some("Horizon TAA"),
+            bind_group_layouts: &[Some(&taa_layout)],
+            ..Default::default()
+        });
+        let pipeline = |entry: &str, layout: &wgpu::PipelineLayout, format| {
+            device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+                label: Some("Horizon post"),
+                layout: Some(layout),
+                vertex: wgpu::VertexState {
+                    module: &shader,
+                    entry_point: Some("vs_post"),
+                    compilation_options: Default::default(),
+                    buffers: &[],
+                },
+                primitive: Default::default(),
+                depth_stencil: None,
+                multisample: Default::default(),
+                fragment: Some(wgpu::FragmentState {
+                    module: &shader,
+                    entry_point: Some(entry),
+                    compilation_options: Default::default(),
+                    targets: &[Some(wgpu::ColorTargetState {
+                        format,
+                        blend: None,
+                        write_mask: wgpu::ColorWrites::ALL,
+                    })],
+                }),
+                multiview_mask: None,
+                cache: None,
+            })
+        };
+        let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
+            label: Some("Horizon post"),
+            mag_filter: wgpu::FilterMode::Linear,
+            min_filter: wgpu::FilterMode::Linear,
+            ..Default::default()
+        });
+        Self {
+            copy: pipeline("fs_copy", &pipeline_layout, format),
+            fxaa: pipeline("fs_fxaa", &pipeline_layout, format),
+            taa_pipeline: pipeline("fs_taa", &taa_pipeline_layout, HISTORY_FORMAT),
+            taa_uniform: device.create_buffer(&wgpu::BufferDescriptor {
+                label: Some("Horizon TAA"),
+                size: std::mem::size_of::<TaaUniform>() as u64,
+                usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
+                mapped_at_creation: false,
+            }),
+            layout,
+            taa_layout,
+            sampler,
+            format,
+            scale: 1.0,
+            antialias: false,
+            taa: false,
+            upscale: 1.0,
+            taa_on: false,
+            target: None,
+            taa_frame: 0,
+            taa_previous: None,
+            taa_this_frame: bytemuck::Zeroable::zeroed(),
+        }
+    }
+
+    /// The world's rendered size and the size it is shown at (TAA's history).
+    fn sizes(&self, window: [u32; 2]) -> ([u32; 2], [u32; 2]) {
+        let output = window.map(|v| ((v as f32 * self.scale).round() as u32).clamp(1, 8192));
+        let upscale = if self.taa_on { self.upscale } else { 1.0 };
+        (
+            output.map(|v| ((v as f32 / upscale).round() as u32).max(1)),
+            output,
+        )
+    }
+
+    /// TAA's sub-pixel jitter this frame, as a clip-space matrix to multiply into the
+    /// world's projection (identity while `on` is false); `view_proj` is the unjittered
+    /// projection, relative to `camera`. Call it before `prepare`, once per frame.
+    pub fn jitter(&mut self, window: [u32; 2], on: bool, view_proj: Mat4, camera: DVec3) -> Mat4 {
+        self.taa_on = on && self.taa;
+        if !self.taa_on {
+            self.taa_previous = None;
+            return Mat4::IDENTITY;
+        }
+        self.taa_frame = self.taa_frame.wrapping_add(1);
+        let (size, _) = self.sizes(window);
+        // Halton (2, 3) over 8 frames per output pixel (FSR's count), in rendered
+        // pixels around the centre.
+        let phases = (8.0 * self.upscale * self.upscale).ceil() as u32;
+        let i = self.taa_frame % phases + 1;
+        let offset = Vec2::new(halton(i, 2), halton(i, 3)) - 0.5;
+        let jitter = offset * 2.0 / Vec2::new(size[0] as f32, size[1] as f32);
+        let current = view_proj.as_dmat4();
+        let (reproject, reset) = match self.taa_previous {
+            Some((previous, previous_camera)) => (
+                reprojection(previous, previous_camera, current, camera),
+                0.0,
+            ),
+            None => (DMat4::IDENTITY, 1.0),
+        };
+        self.taa_previous = Some((current, camera));
+        self.taa_this_frame = TaaUniform {
+            reproject: reproject.as_mat4().to_cols_array_2d(),
+            jitter: [jitter.x, jitter.y, reset, 0.0],
+        };
+        Mat4::from_translation(jitter.extend(0.0))
+    }
+
+    /// The world's colour and depth targets this frame, or `None` to draw
+    /// it straight to the screen.
+    /// `always`: a target even at scale 1 without anti-aliasing (a shader pack reads it).
+    pub fn prepare(
+        &mut self,
+        device: &wgpu::Device,
+        window: [u32; 2],
+        always: bool,
+    ) -> Option<(wgpu::TextureView, wgpu::TextureView)> {
+        if self.scale == 1.0 && !self.antialias && !self.taa_on && !always {
+            self.target = None;
+            return None;
+        }
+        let (size, output) = self.sizes(window);
+        let history_size = self.taa_on.then_some(output);
+        if self
+            .target
+            .as_ref()
+            .is_none_or(|t| t.size != size || t.taa.as_ref().map(|h| h.size) != history_size)
+        {
+            let make_tex = |label, size: [u32; 2], format, usage| {
+                device.create_texture(&wgpu::TextureDescriptor {
+                    label: Some(label),
+                    size: wgpu::Extent3d {
+                        width: size[0],
+                        height: size[1],
+                        depth_or_array_layers: 1,
+                    },
+                    mip_level_count: 1,
+                    sample_count: 1,
+                    dimension: wgpu::TextureDimension::D2,
+                    format,
+                    usage,
+                    view_formats: &[],
+                })
+            };
+            let sampled =
+                wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::TEXTURE_BINDING;
+            let color = make_tex("Scaled world", size, self.format, sampled)
+                .create_view(&Default::default());
+            // TEXTURE_BINDING: occlusion culling and TAA read it.
+            let depth = make_tex(
+                "Scaled world depth",
+                size,
+                wgpu::TextureFormat::Depth32Float,
+                sampled,
+            )
+            .create_view(&Default::default());
+            let group = self.bind(device, &color);
+            let taa = history_size.map(|output| {
+                let history = [0, 1].map(|_| {
+                    make_tex("TAA history", output, HISTORY_FORMAT, sampled)
+                        .create_view(&Default::default())
+                });
+                let resolve = [0, 1].map(|i| {
+                    device.create_bind_group(&wgpu::BindGroupDescriptor {
+                        label: Some("Horizon TAA"),
+                        layout: &self.taa_layout,
+                        entries: &[
+                            wgpu::BindGroupEntry {
+                                binding: 0,
+                                resource: wgpu::BindingResource::TextureView(&color),
+                            },
+                            wgpu::BindGroupEntry {
+                                binding: 1,
+                                resource: wgpu::BindingResource::Sampler(&self.sampler),
+                            },
+                            wgpu::BindGroupEntry {
+                                binding: 2,
+                                resource: wgpu::BindingResource::TextureView(&history[1 - i]),
+                            },
+                            wgpu::BindGroupEntry {
+                                binding: 3,
+                                resource: wgpu::BindingResource::TextureView(&depth),
+                            },
+                            wgpu::BindGroupEntry {
+                                binding: 4,
+                                resource: self.taa_uniform.as_entire_binding(),
+                            },
+                        ],
+                    })
+                });
+                let show = [0, 1].map(|i| self.bind(device, &history[i]));
+                History {
+                    size: output,
+                    history,
+                    resolve,
+                    show,
+                }
+            });
+            // New textures: no history yet.
+            self.taa_this_frame.jitter[2] = 1.0;
+            self.target = Some(WorldTarget {
+                size,
+                color,
+                depth,
+                group,
+                taa,
+            });
+        }
+        self.target
+            .as_ref()
+            .map(|t| (t.color.clone(), t.depth.clone()))
+    }
+
+    /// The size of the world's own target, when it has one.
+    pub fn size(&self) -> Option<[u32; 2]> {
+        self.target.as_ref().map(|t| t.size)
+    }
+
+    /// Bindings that copy (or anti-alias) `view` onto the screen in `finish_with`.
+    pub fn bind(&self, device: &wgpu::Device, view: &wgpu::TextureView) -> wgpu::BindGroup {
+        device.create_bind_group(&wgpu::BindGroupDescriptor {
+            label: Some("Horizon post"),
+            layout: &self.layout,
+            entries: &[
+                wgpu::BindGroupEntry {
+                    binding: 0,
+                    resource: wgpu::BindingResource::TextureView(view),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 1,
+                    resource: wgpu::BindingResource::Sampler(&self.sampler),
+                },
+            ],
+        })
+    }
+
+    /// Draw the scaled world onto `screen`, through TAA when this frame's `jitter` had it on.
+    pub fn finish(
+        &self,
+        queue: &wgpu::Queue,
+        encoder: &mut wgpu::CommandEncoder,
+        screen: &wgpu::TextureView,
+    ) {
+        let Some(target) = &self.target else { return };
+        let Some(taa) = target.taa.as_ref().filter(|_| self.taa_previous.is_some()) else {
+            self.finish_with(encoder, screen, &target.group);
+            return;
+        };
+        let i = (self.taa_frame % 2) as usize;
+        queue.write_buffer(
+            &self.taa_uniform,
+            0,
+            bytemuck::bytes_of(&self.taa_this_frame),
+        );
+        let attachments = [Some(wgpu::RenderPassColorAttachment {
+            view: &taa.history[i],
+            resolve_target: None,
+            depth_slice: None,
+            ops: wgpu::Operations {
+                load: wgpu::LoadOp::Clear(wgpu::Color::BLACK),
+                store: wgpu::StoreOp::Store,
+            },
+        })];
+        let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: Some("Horizon TAA"),
+            color_attachments: &attachments,
+            ..Default::default()
+        });
+        pass.set_pipeline(&self.taa_pipeline);
+        pass.set_bind_group(0, &taa.resolve[i], &[]);
+        pass.draw(0..3, 0..1);
+        drop(pass);
+        self.finish_with(encoder, screen, &taa.show[i]);
+    }
+
+    /// Draw what `group` binds (`bind`) onto `screen`.
+    pub fn finish_with(
+        &self,
+        encoder: &mut wgpu::CommandEncoder,
+        screen: &wgpu::TextureView,
+        group: &wgpu::BindGroup,
+    ) {
+        let attachments = [Some(wgpu::RenderPassColorAttachment {
+            view: screen,
+            resolve_target: None,
+            depth_slice: None,
+            ops: wgpu::Operations {
+                load: wgpu::LoadOp::Clear(wgpu::Color::BLACK),
+                store: wgpu::StoreOp::Store,
+            },
+        })];
+        let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+            label: Some("Horizon post"),
+            color_attachments: &attachments,
+            ..Default::default()
+        });
+        pass.set_pipeline(if self.antialias {
+            &self.fxaa
+        } else {
+            &self.copy
+        });
+        pass.set_bind_group(0, group, &[]);
+        pass.draw(0..3, 0..1);
+    }
+}
+
+/// This frame's clip space to the previous frame's, for camera-relative projections:
+/// a point `camera - previous_camera` further from the previous camera than from this one.
+fn reprojection(previous: DMat4, previous_camera: DVec3, current: DMat4, camera: DVec3) -> DMat4 {
+    previous * DMat4::from_translation(camera - previous_camera) * current.inverse()
+}
+
+/// The radical inverse of `i` in `base`: a low-discrepancy sequence in 0..1.
+fn halton(mut i: u32, base: u32) -> f32 {
+    let (mut f, mut r) = (1.0, 0.0);
+    while i > 0 {
+        f /= base as f32;
+        r += f * (i % base) as f32;
+        i /= base;
+    }
+    r
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn reprojection_finds_where_a_block_was_last_frame() {
+        let projection = DMat4::perspective_rh(1.2, 16.0 / 9.0, 1024.0, 0.05);
+        let previous = projection * DMat4::from_rotation_y(0.3);
+        let current = projection * DMat4::from_rotation_y(0.35);
+        let (previous_camera, camera) = (DVec3::new(10.0, 64.0, 5.0), DVec3::new(10.5, 64.2, 4.0));
+        let block = DVec3::new(14.0, 66.0, -8.0);
+        let clip = |m: DMat4, eye: DVec3| m * (block - eye).extend(1.0);
+        let now = clip(current, camera);
+        let then = reprojection(previous, previous_camera, current, camera) * (now / now.w);
+        let expected = clip(previous, previous_camera);
+        assert!((then.truncate() / then.w - expected.truncate() / expected.w).length() < 1e-9);
+    }
+
+    #[test]
+    fn jitter_stays_inside_the_pixel() {
+        for i in 1..=8 {
+            let (x, y) = (halton(i, 2), halton(i, 3));
+            assert!((0.0..1.0).contains(&x) && (0.0..1.0).contains(&y));
+        }
+        assert_eq!(
+            [halton(1, 2), halton(2, 2), halton(3, 2)],
+            [0.5, 0.25, 0.75]
+        );
+    }
+}

crates/horizon-client-render/src/graphics.rs

@@ -96,9 +96,9 @@ impl PresentMode {
     }
 }
 
-/// The graphics API the renderer runs on. Only Windows has a choice: the
-/// other systems always use their one backend (Vulkan on Linux, Metal on
-/// macOS). Applies at the next start.
+/// The graphics API the renderer runs on. Windows picks Vulkan, DirectX 12 or
+/// OpenGL; Linux picks Vulkan or OpenGL; macOS always uses its one backend
+/// (Metal). Applies at the next start.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
 pub enum GraphicsApi {
     /// Vulkan, then DirectX 12 (Windows), then OpenGL when neither has a surface, adapter or device.
@@ -116,6 +116,26 @@ impl GraphicsApi {
         GraphicsApi::Dx12,
         GraphicsApi::OpenGl,
     ];
+    /// The APIs this system offers, in the order the setting cycles through
+    /// them: DirectX 12 is Windows' third backend, and macOS has no choice.
+    pub fn choices() -> &'static [GraphicsApi] {
+        const WINDOWS: [GraphicsApi; 4] = [
+            GraphicsApi::Auto,
+            GraphicsApi::Vulkan,
+            GraphicsApi::Dx12,
+            GraphicsApi::OpenGl,
+        ];
+        const LINUX: [GraphicsApi; 3] =
+            [GraphicsApi::Auto, GraphicsApi::Vulkan, GraphicsApi::OpenGl];
+        const MACOS: [GraphicsApi; 1] = [GraphicsApi::Auto];
+        if cfg!(windows) {
+            &WINDOWS
+        } else if cfg!(target_os = "macos") {
+            &MACOS
+        } else {
+            &LINUX
+        }
+    }
     pub fn name(self) -> &'static str {
         match self {
             GraphicsApi::Auto => "auto",
@@ -200,6 +220,61 @@ impl FarDetail {
     }
 }
 
+/// TAA upscaling: the world renders this much smaller than the resolution scale's size,
+/// and TAA builds the full-size picture from the jittered frames (FSR's and DLSS's ratios).
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
+pub enum Upscaling {
+    #[default]
+    Native,
+    Quality,
+    Balanced,
+    Performance,
+    UltraPerformance,
+}
+impl Upscaling {
+    pub const ALL: [Upscaling; 5] = [
+        Upscaling::Native,
+        Upscaling::Quality,
+        Upscaling::Balanced,
+        Upscaling::Performance,
+        Upscaling::UltraPerformance,
+    ];
+    pub fn name(self) -> &'static str {
+        match self {
+            Upscaling::Native => "native",
+            Upscaling::Quality => "quality",
+            Upscaling::Balanced => "balanced",
+            Upscaling::Performance => "performance",
+            Upscaling::UltraPerformance => "ultraPerformance",
+        }
+    }
+    pub fn label(self) -> &'static str {
+        match self {
+            Upscaling::Native => "Native",
+            Upscaling::Quality => "Quality",
+            Upscaling::Balanced => "Balanced",
+            Upscaling::Performance => "Performance",
+            Upscaling::UltraPerformance => "Ultra Performance",
+        }
+    }
+    /// Output pixels per rendered pixel, along each axis.
+    pub fn ratio(self) -> f32 {
+        match self {
+            Upscaling::Native => 1.0,
+            Upscaling::Quality => 1.5,
+            Upscaling::Balanced => 1.7,
+            Upscaling::Performance => 2.0,
+            Upscaling::UltraPerformance => 3.0,
+        }
+    }
+    fn parse(s: &str) -> Self {
+        Self::ALL
+            .into_iter()
+            .find(|u| u.name() == s)
+            .unwrap_or_default()
+    }
+}
+
 static REDUCED_SUGGESTED: std::sync::atomic::AtomicBool = std::sync::atomic::AtomicBool::new(false);
 /// Whether the settings suggest Reduced far detail: set when the renderer
 /// starts, on the GPUs `lod_capped` names (far terrain slows them most).
@@ -262,6 +337,10 @@ pub struct Graphics {
     pub resolution_scale: u32,
     /// FXAA over the world.
     pub fxaa: bool,
+    /// TAA over the world (FXAA is off while it is on).
+    pub taa: bool,
+    /// TAA upscaling; anything but `Native` comes with `taa` on.
+    pub upscaling: Upscaling,
     /// HDR output (HDR10, or scRGB), where the display path offers it.
     pub hdr: bool,
     /// HDR paper white (where SDR white sits), in nits.
@@ -299,6 +378,8 @@ impl Default for Graphics {
             overlay: Overlay::Off,
             resolution_scale: 100,
             fxaa: false,
+            taa: false,
+            upscaling: Upscaling::Native,
             hdr: false,
             hdr_paper_white: 200,
             hdr_peak: 1000,
@@ -361,6 +442,8 @@ impl Graphics {
                 "workers" => g.workers = number(g.workers).min(64),
                 "resolutionScale" => g.resolution_scale = number(g.resolution_scale).clamp(50, 200),
                 "fxaa" => g.fxaa = flag(g.fxaa),
+                "taa" => g.taa = flag(g.taa),
+                "upscaling" => g.upscaling = Upscaling::parse(value),
                 "hdr" => g.hdr = flag(g.hdr),
                 "hdrPaperWhite" => g.hdr_paper_white = number(g.hdr_paper_white).clamp(80, 480),
                 "hdrPeak" => g.hdr_peak = number(g.hdr_peak).clamp(200, 2000),
@@ -381,7 +464,7 @@ impl Graphics {
     }
     pub fn serialize(&self) -> String {
         format!(
-            "preset:{}\nlodDistance:{}\nfarDetail:{}\ncaveCulling:{}\nentityCulling:{}\nchunkUpdates:{}\nuploadBudgetKiB:{}\nsky:{}\nfog:{}\nweather:{}\nanimatedTextures:{}\npresentMode:{}\nframePacing:{}\nworkers:{}\noverlay:{}\nresolutionScale:{}\nfxaa:{}\nhdr:{}\nhdrPaperWhite:{}\nhdrPeak:{}\nbatteryMode:{}\ngraphicsApi:{}\npickedShaderPack:{}\n",
+            "preset:{}\nlodDistance:{}\nfarDetail:{}\ncaveCulling:{}\nentityCulling:{}\nchunkUpdates:{}\nuploadBudgetKiB:{}\nsky:{}\nfog:{}\nweather:{}\nanimatedTextures:{}\npresentMode:{}\nframePacing:{}\nworkers:{}\noverlay:{}\nresolutionScale:{}\nfxaa:{}\ntaa:{}\nupscaling:{}\nhdr:{}\nhdrPaperWhite:{}\nhdrPeak:{}\nbatteryMode:{}\ngraphicsApi:{}\npickedShaderPack:{}\n",
             self.preset.name(),
             self.lod_distance,
             self.far_detail.name(),
@@ -406,6 +489,8 @@ impl Graphics {
             },
             self.resolution_scale,
             bool_text(self.fxaa),
+            bool_text(self.taa),
+            self.upscaling.name(),
             bool_text(self.hdr),
             self.hdr_paper_white,
             self.hdr_peak,
@@ -486,6 +571,21 @@ pub fn apply_preset(preset: Preset, s: &mut crate::settings::Settings) {
 mod tests {
     use super::*;
 
+    #[test]
+    fn the_api_choice_matches_the_system() {
+        let choices = GraphicsApi::choices();
+        if cfg!(windows) {
+            assert_eq!(choices, GraphicsApi::ALL);
+        } else if cfg!(target_os = "macos") {
+            assert_eq!(choices, [GraphicsApi::Auto]);
+        } else {
+            assert_eq!(
+                choices,
+                [GraphicsApi::Auto, GraphicsApi::Vulkan, GraphicsApi::OpenGl]
+            );
+        }
+    }
+
     #[test]
     fn round_trips() {
         let g = Graphics {
@@ -506,6 +606,8 @@ mod tests {
             overlay: Overlay::Graph,
             resolution_scale: 75,
             fxaa: true,
+            taa: true,
+            upscaling: Upscaling::Balanced,
             hdr: true,
             hdr_paper_white: 240,
             hdr_peak: 1400,

crates/horizon-client-render/src/graphics_ui.rs

@@ -2,7 +2,7 @@
 //! they show, in what groups, with what description and cost, and their
 //! input. How they look comes from `graphics_style`.
 use crate::{
-    graphics::{FarDetail, GraphicsApi, Overlay, Pacing, PresentMode, Preset},
+    graphics::{FarDetail, GraphicsApi, Overlay, Pacing, PresentMode, Preset, Upscaling},
     graphics_style::{Cost, STYLE},
     hud::{HudAtlas, HudBatch},
     settings::{Opt, Settings},
@@ -36,6 +36,7 @@ pub enum H {
     Overlay,
     ResolutionScale,
     Antialiasing,
+    Upscaling,
     Hdr,
     HdrPaperWhite,
     HdrPeak,
@@ -221,7 +222,12 @@ pub fn rows(level: Level) -> Vec<Row> {
             h(
                 H::Antialiasing,
                 Medium,
-                "FXAA smooths jagged edges of the world; slightly softer image.",
+                "Smooths jagged edges. FXAA: softer. TAA: smoothest, moving things may trail.",
+            ),
+            h(
+                H::Upscaling,
+                High,
+                "Renders the world smaller and rebuilds it with TAA. Faster, softer.",
             ),
             h(
                 H::Hdr,
@@ -276,7 +282,7 @@ pub fn rows(level: Level) -> Vec<Row> {
             h(
                 H::GraphicsApi,
                 None,
-                "Vulkan, or DirectX 12 where Vulkan fails. Next start.",
+                "Vulkan, then DirectX 12 (Windows) or OpenGL (Linux) where it fails. Next start.",
             ),
             h(
                 H::UploadBudget,
@@ -291,8 +297,8 @@ pub fn rows(level: Level) -> Vec<Row> {
             ),
         ],
     };
-    // Only Windows has more than one graphics API.
-    if !cfg!(windows) {
+    // Only Windows and Linux have more than one graphics API.
+    if cfg!(target_os = "macos") {
         rows.retain(
             |row| !matches!(row, Row::Setting(s) if s.item == Item::Horizon(H::GraphicsApi)),
         );
@@ -303,9 +309,13 @@ pub fn rows(level: Level) -> Vec<Row> {
 const UPLOAD_STEPS: [u32; 8] = [0, 256, 512, 1024, 2048, 4096, 8192, 16384];
 
 /// Horizon's graphics screens supplement the vanilla options on Video Settings.
-fn extra_rows(level: Level) -> Vec<Row> {
+/// Upscaling is only there while TAA is, which does it.
+fn extra_rows(level: Level, settings: &Settings) -> Vec<Row> {
     let mut rows = rows(level);
     rows.retain(|row| !matches!(row, Row::Setting(s) if matches!(s.item, Item::Vanilla(_))));
+    if !settings.horizon.taa {
+        rows.retain(|row| !matches!(row, Row::Setting(s) if s.item == Item::Horizon(H::Upscaling)));
+    }
     // Drop headings whose settings were all on the parent screens.
     let mut has_setting = false;
     rows.reverse();
@@ -383,7 +393,15 @@ impl H {
                 n => labelled("Worker Threads", n),
             },
             H::ResolutionScale => labelled("Resolution Scale", format!("{}%", g.resolution_scale)),
-            H::Antialiasing => labelled("Anti-aliasing", if g.fxaa { "FXAA" } else { "Off" }),
+            H::Antialiasing => labelled(
+                "Anti-aliasing",
+                match (g.fxaa, g.taa) {
+                    (_, true) => "TAA",
+                    (true, false) => "FXAA",
+                    (false, false) => "Off",
+                },
+            ),
+            H::Upscaling => labelled("Upscaling", g.upscaling.label()),
             H::Hdr => labelled("HDR", on_off(g.hdr)),
             H::HdrPaperWhite => labelled("Paper White", format!("{} nits", g.hdr_paper_white)),
             H::HdrPeak => labelled("Peak Brightness", format!("{} nits", g.hdr_peak)),
@@ -441,10 +459,25 @@ impl H {
             H::Weather => g.weather = !g.weather,
             H::AnimatedTextures => g.animated_textures = !g.animated_textures,
             H::PresentMode => g.present_mode = step(&PresentMode::ALL, g.present_mode, back),
-            H::Antialiasing => g.fxaa = !g.fxaa,
+            // Off, FXAA, TAA.
+            H::Antialiasing => {
+                let i = if g.taa { 2 } else { usize::from(g.fxaa) };
+                let i = (i + if back { 2 } else { 1 }) % 3;
+                (g.fxaa, g.taa) = (i == 1, i == 2);
+                if !g.taa {
+                    g.upscaling = Upscaling::Native;
+                }
+            }
+            // Upscaling is TAA's: picking a ratio turns it on.
+            H::Upscaling => {
+                g.upscaling = step(&Upscaling::ALL, g.upscaling, back);
+                if g.upscaling != Upscaling::Native {
+                    (g.fxaa, g.taa) = (false, true);
+                }
+            }
             H::Hdr => g.hdr = !g.hdr,
             H::BatteryMode => g.battery = !g.battery,
-            H::GraphicsApi => g.api = step(&GraphicsApi::ALL, g.api, back),
+            H::GraphicsApi => g.api = step(GraphicsApi::choices(), g.api, back),
             H::Pacing => {
                 g.pacing = match g.pacing {
                     Pacing::Efficient => Pacing::Precise,
@@ -481,7 +514,6 @@ impl Item {
             Item::Horizon(H::Fog) => g.fog,
             Item::Horizon(H::Weather) => g.weather,
             Item::Horizon(H::AnimatedTextures) => g.animated_textures,
-            Item::Horizon(H::Antialiasing) => g.fxaa,
             Item::Horizon(H::Hdr) => g.hdr,
             Item::Horizon(H::BatteryMode) => g.battery,
             Item::Vanilla(Opt::ViewBobbing) => s.view_bobbing,
@@ -570,6 +602,7 @@ impl Item {
 pub enum Action {
     ButtonClick,
     Changed,
+    SliderDrag,
     OpenAdvanced,
     OpenSimple,
     Done,
@@ -603,8 +636,8 @@ impl GraphicsUi {
     fn bounds(h: f32) -> (f32, f32) {
         (STYLE.band, h - STYLE.band)
     }
-    fn content_height(level: Level) -> f32 {
-        extra_rows(level).iter().fold(4.0, |height, row| {
+    fn content_height(level: Level, s: &Settings) -> f32 {
+        extra_rows(level, s).iter().fold(4.0, |height, row| {
             height
                 + match row {
                     Row::Header(_) => STYLE.header_height,
@@ -616,17 +649,18 @@ impl GraphicsUi {
     fn layout(
         &mut self,
         level: Level,
+        s: &Settings,
         w: f32,
         h: f32,
     ) -> (Vec<Widget>, Vec<(f32, &'static str)>, f32) {
-        let content = Self::content_height(level);
+        let content = Self::content_height(level, s);
         self.clamp_scroll(h, content);
         let (top, _) = Self::bounds(h);
         let x = STYLE.row_x(w);
         let mut y = top + 4.0 - self.scroll;
         let mut widgets = Vec::new();
         let mut headers = Vec::new();
-        for row in extra_rows(level) {
+        for row in extra_rows(level, s) {
             match row {
                 Row::Header(name) => {
                     headers.push((y, name));
@@ -680,7 +714,7 @@ impl GraphicsUi {
         in_world: bool,
     ) {
         let (w, h) = (batch.width, batch.height);
-        let (widgets, headers, content) = self.layout(level, w, h);
+        let (widgets, headers, content) = self.layout(level, s, w, h);
         let (top, bottom) = Self::bounds(h);
         STYLE.background(batch, atlas, top, bottom, in_world);
         let shown = |y: f32, height: f32| y >= top && y + height <= bottom;
@@ -690,7 +724,7 @@ impl GraphicsUi {
                 STYLE.header(batch, atlas, &Text::literal(name), x, y);
             }
         }
-        let descriptions: Vec<(Cost, &'static str)> = extra_rows(level)
+        let descriptions: Vec<(Cost, &'static str)> = extra_rows(level, s)
             .into_iter()
             .filter_map(|r| match r {
                 Row::Setting(s) => Some((s.cost, s.text)),
@@ -791,7 +825,7 @@ impl GraphicsUi {
         drag: bool,
         right: bool,
     ) -> Vec<Action> {
-        let (widgets, _, _) = self.layout(level, w, h);
+        let (widgets, _, _) = self.layout(level, s, w, h);
         let (top, bottom) = Self::bounds(h);
         if drag {
             if let Some(item) = self.dragging
@@ -800,7 +834,7 @@ impl GraphicsUi {
                     .find(|wd| matches!(wd.target, Target::Item(i) if i == item))
             {
                 item.set_slider(s, ui::slider_value(wd.x, wd.w, x));
-                return vec![Action::Changed];
+                return vec![Action::SliderDrag];
             }
             return Vec::new();
         }
@@ -822,11 +856,11 @@ impl GraphicsUi {
                     if item.slider(s).is_some() {
                         self.dragging = Some(item);
                         item.set_slider(s, ui::slider_value(wd.x, wd.w, x));
+                        vec![Action::SliderDrag]
                     } else {
                         item.cycle(s, right, framebuffer);
-                        return vec![Action::ButtonClick, Action::Changed];
+                        vec![Action::ButtonClick, Action::Changed]
                     }
-                    vec![Action::Changed]
                 }
             };
         }
@@ -835,8 +869,8 @@ impl GraphicsUi {
     pub fn release(&mut self) -> bool {
         self.dragging.take().is_some()
     }
-    pub fn scroll(&mut self, level: Level, h: f32, amount: f32) {
-        let content = Self::content_height(level);
+    pub fn scroll(&mut self, level: Level, s: &Settings, h: f32, amount: f32) {
+        let content = Self::content_height(level, s);
         self.clamp_scroll(h, content);
         self.scroll -= amount * 18.0;
         self.clamp_scroll(h, content);
@@ -852,7 +886,7 @@ mod tests {
         let mut s = Settings::default();
         let mut ui = GraphicsUi::default();
         let size = (480.0, 320.0);
-        let (widgets, _, _) = ui.layout(Level::Advanced, size.0, size.1);
+        let (widgets, _, _) = ui.layout(Level::Advanced, &s, size.0, size.1);
         let button = widgets
             .iter()
             .find(|w| matches!(w.target, Target::Button(_)))
@@ -897,7 +931,7 @@ mod tests {
                 false,
                 false
             ),
-            vec![Action::Changed]
+            vec![Action::SliderDrag]
         );
         assert_eq!(
             ui.click(
@@ -909,7 +943,7 @@ mod tests {
                 true,
                 false
             ),
-            vec![Action::Changed]
+            vec![Action::SliderDrag]
         );
         assert!(ui.release());
         assert!(!ui.release());
@@ -917,45 +951,47 @@ mod tests {
 
     #[test]
     fn scrolling_stops_at_both_limits_before_layout() {
+        let s = Settings::default();
         for level in [Level::Simple, Level::Advanced] {
             let mut ui = GraphicsUi::default();
             let h = 2.0 * STYLE.band + 10.0;
             let (top, bottom) = GraphicsUi::bounds(h);
-            let max = GraphicsUi::content_height(level) - (bottom - top);
+            let max = GraphicsUi::content_height(level, &s) - (bottom - top);
             assert!(max > 4.5);
             for _ in 0..3 {
-                ui.scroll(level, h, 1000.0);
+                ui.scroll(level, &s, h, 1000.0);
                 assert_eq!(ui.scroll, 0.0);
             }
             for _ in 0..3 {
-                ui.scroll(level, h, -1000.0);
+                ui.scroll(level, &s, h, -1000.0);
                 assert_eq!(ui.scroll, max);
             }
-            ui.scroll(level, h, 0.25);
+            ui.scroll(level, &s, h, 0.25);
             assert_eq!(ui.scroll, max - 4.5);
-            ui.scroll(level, h, 1000.0);
-            ui.scroll(level, h, -0.25);
+            ui.scroll(level, &s, h, 1000.0);
+            ui.scroll(level, &s, h, -0.25);
             assert_eq!(ui.scroll, 4.5);
         }
     }
 
     #[test]
     fn resizing_clamps_before_positioning_graphics_rows() {
+        let s = Settings::default();
         for level in [Level::Simple, Level::Advanced] {
             let mut ui = GraphicsUi::default();
-            ui.scroll(level, 2.0 * STYLE.band + 10.0, -1000.0);
+            ui.scroll(level, &s, 2.0 * STYLE.band + 10.0, -1000.0);
             assert!(ui.scroll > 0.0);
-            let (widgets, headers, _) = ui.layout(level, 480.0, 4000.0);
+            let (widgets, headers, _) = ui.layout(level, &s, 480.0, 4000.0);
             assert_eq!(ui.scroll, 0.0);
             if let Some((y, _)) = headers.first() {
                 assert_eq!(*y, STYLE.band + 4.0);
             }
-            let (expected, _, _) = GraphicsUi::default().layout(level, 480.0, 4000.0);
+            let (expected, _, _) = GraphicsUi::default().layout(level, &s, 480.0, 4000.0);
             assert_eq!(
                 widgets.iter().map(|w| w.y).collect::<Vec<_>>(),
                 expected.iter().map(|w| w.y).collect::<Vec<_>>()
             );
-            ui.scroll(level, 4000.0, -1000.0);
+            ui.scroll(level, &s, 4000.0, -1000.0);
             assert_eq!(ui.scroll, 0.0);
         }
     }
@@ -963,7 +999,7 @@ mod tests {
     #[test]
     fn classic_submenus_only_add_horizon_settings_without_empty_groups() {
         for level in [Level::Simple, Level::Advanced] {
-            let rows = extra_rows(level);
+            let rows = extra_rows(level, &Settings::default());
             assert!(rows.iter().any(|row| matches!(row, Row::Setting(_))));
             for (i, row) in rows.iter().enumerate() {
                 match row {
@@ -1051,6 +1087,37 @@ mod tests {
         assert_eq!(s.horizon.upload_budget_kib, 0);
     }
 
+    #[test]
+    fn antialiasing_cycles_off_fxaa_taa() {
+        let mut s = Settings::default();
+        let item = Item::Horizon(H::Antialiasing);
+        for label in ["FXAA", "TAA", "Off"] {
+            item.cycle(&mut s, false, [854, 480]);
+            assert_eq!(item.label(&s).plain(), format!("Anti-aliasing: {label}"));
+        }
+        item.cycle(&mut s, true, [854, 480]);
+        assert_eq!((s.horizon.fxaa, s.horizon.taa), (false, true));
+
+        // Upscaling needs TAA: a ratio turns it on, leaving TAA goes back to Native.
+        s.horizon.taa = false;
+        let upscaling = Item::Horizon(H::Upscaling);
+        upscaling.cycle(&mut s, false, [854, 480]);
+        assert_eq!(upscaling.label(&s).plain(), "Upscaling: Quality");
+        assert!(s.horizon.taa);
+        item.cycle(&mut s, false, [854, 480]);
+        assert_eq!(s.horizon.upscaling, Upscaling::Native);
+
+        // The Upscaling row is only on the screen while TAA is on.
+        let shown = |s: &Settings| {
+            extra_rows(Level::Advanced, s)
+                .iter()
+                .any(|row| matches!(row, Row::Setting(r) if r.item == upscaling))
+        };
+        assert!(!shown(&s));
+        s.horizon.taa = true;
+        assert!(shown(&s));
+    }
+
     #[test]
     fn entity_culling_is_opt_in_and_toggles_from_advanced_graphics() {
         let mut s = Settings::default();
@@ -1067,7 +1134,7 @@ mod tests {
 
         let mut ui = GraphicsUi::default();
         let size = (480.0, 4000.0);
-        let (widgets, _, _) = ui.layout(Level::Advanced, size.0, size.1);
+        let (widgets, _, _) = ui.layout(Level::Advanced, &s, size.0, size.1);
         let switch = widgets
             .iter()
             .find(|w| matches!(w.target, Target::Item(i) if i == item))