The item_stack helper draws nothing for an empty stack

GuiGraphicsExtractor.item and itemDecorations skip an empty stack (air,
or a count of 0), so native_item_stack now returns false for one instead
of drawing a ghost icon. Regenerating the mod API also refreshes the
native_projectile_impact doc that main had left stale.

Fixes #6968.

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

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

@@ -6932,7 +6932,9 @@ impl Game<'_> {
         true
     }
     /// Draw a stack and its slot decorations, except the count, at `at`,
-    /// `size` GUI pixels square. False for an unknown item. API @API:item_stack@.
+    /// `size` GUI pixels square. False when nothing was drawn: an unknown item
+    /// or an empty stack (air, or a count of 0, as `ItemStack.isEmpty`).
+    /// API @API:item_stack@.
     pub(super) fn native_item_stack(
         &self,
         batch: &mut HudBatch,
@@ -6940,6 +6942,11 @@ impl Game<'_> {
         at: [f32; 2],
         size: f32,
     ) -> bool {
+        // GuiGraphicsExtractor.item and itemDecorations draw nothing for an
+        // empty stack.
+        if &*stack.item == "minecraft:air" || stack.count == 0 {
+            return false;
+        }
         if self.res.items().get(&stack.item).is_none() {
             return false;
         }

crates/horizon-client/src/mod_api/generated.rs

@@ -2013,10 +2013,9 @@ pub trait Hooks: Send + Sync {
     /// does not happen: no damage, no knockback, no sound, no block reaction, the
     /// arrow does not stick, a pearl does not teleport, a potion or a fireball
     /// does not burst. The projectile flies on and is not discarded, so a mod
-    /// that cancels also decides what becomes of it: it hits again the next tick
-    /// unless the mod moves, turns or removes it. An arrow stays where it would
-    /// have hit, and the other projectiles go on through the whole of their
-    /// motion. Covers what `tick_projectiles` flies: arrows, tridents, snowballs,
+    /// that cancels also decides what becomes of it. It continues through its
+    /// whole motion and may hit something on a later tick. Covers what
+    /// `tick_projectiles` flies: arrows, tridents, snowballs,
     /// eggs, pearls, potions, fireballs, wither skulls, wind charges, llama spit and
     /// shulker bullets, from players, mobs and dispensers. It does not fire for
     /// a breeze's deflection, for a hit on a wind charge, for fireworks or for

crates/horizon-client/src/mod_api/generated_host.rs

@@ -665,6 +665,8 @@ pub trait Host {
         max: u32,
     ) -> u32;
     /// Draw a stack and its slot decorations, except the count, at `at`,
-    /// `size` GUI pixels square. False for an unknown item. API @API:item_stack@.
+    /// `size` GUI pixels square. False when nothing was drawn: an unknown item
+    /// or an empty stack (air, or a count of 0, as `ItemStack.isEmpty`).
+    /// API @API:item_stack@.
     fn item_stack(&self, batch: &mut HudBatch, stack: &ItemStack, at: [f32; 2], size: f32) -> bool;
 }

tools/native-hook-fragments/item_stack.json

@@ -4,5 +4,5 @@
     {"name": "item_stack", "target": "horizon_client::game::native_hooks::Game<'_>::native_item_stack"}
   ],
   "rust_summary": "drawing a component-bearing item stack and its decorations on a screen (`native_item_stack`).",
-  "doc_summary": "drawing an item stack on a screen: `native_item_stack(batch, stack, at, size)` draws its model, glint, damage bar, cooldown and mod decorations, but not its count. It returns false for an unknown item. Bundles need \"hooks\": @API:item_stack@."
+  "doc_summary": "drawing an item stack on a screen: `native_item_stack(batch, stack, at, size)` draws its model, glint, damage bar, cooldown and mod decorations, but not its count. It draws nothing and returns false for an unknown item or an empty stack (air, or a count of 0). Bundles need \"hooks\": @API:item_stack@."
 }