[1.21.1] Add event for registering atlases for use with Material

patches/net/minecraft/client/resources/model/ModelManager.java.patch

@@ -1,6 +1,6 @@
 --- a/net/minecraft/client/resources/model/ModelManager.java
 +++ b/net/minecraft/client/resources/model/ModelManager.java
-@@ -63,13 +_,14 @@
+@@ -63,18 +_,20 @@
          TextureAtlas.LOCATION_BLOCKS,
          ResourceLocation.withDefaultNamespace("blocks")
      );
@@ -16,6 +16,12 @@
 
      public ModelManager(TextureManager p_119406_, BlockColors p_119407_, int p_119408_) {
          this.blockColors = p_119407_;
+         this.maxMipmapLevels = p_119408_;
+         this.blockModelShaper = new BlockModelShaper(this);
++        Map<ResourceLocation, ResourceLocation> VANILLA_ATLASES = net.neoforged.neoforge.client.ClientHooks.gatherMaterialAtlases(ModelManager.VANILLA_ATLASES);
+         this.atlases = new AtlasSet(VANILLA_ATLASES, p_119406_);
+     }
+
 @@ -100,6 +_,7 @@
          Executor p_249221_
      ) {

src/main/java/net/neoforged/neoforge/client/ClientHooks.java

@@ -158,6 +158,7 @@
 import net.neoforged.neoforge.client.event.RegisterClientReloadListenersEvent;
 import net.neoforged.neoforge.client.event.RegisterColorHandlersEvent;
 import net.neoforged.neoforge.client.event.RegisterKeyMappingsEvent;
+import net.neoforged.neoforge.client.event.RegisterMaterialAtlasesEvent;
 import net.neoforged.neoforge.client.event.RegisterParticleProvidersEvent;
 import net.neoforged.neoforge.client.event.RegisterShadersEvent;
 import net.neoforged.neoforge.client.event.RegisterSpriteSourceTypesEvent;
@@ -1120,4 +1121,10 @@ public static RecipeBookType[] getFilteredRecipeBookTypeValues() {
         }
         return RECIPE_BOOK_TYPES;
     }
+
+    public static Map<ResourceLocation, ResourceLocation> gatherMaterialAtlases(Map<ResourceLocation, ResourceLocation> vanillaAtlases) {
+        vanillaAtlases = new HashMap<>(vanillaAtlases);
+        ModLoader.postEvent(new RegisterMaterialAtlasesEvent(vanillaAtlases));
+        return Map.copyOf(vanillaAtlases);
+    }
 }

src/main/java/net/neoforged/neoforge/client/event/RegisterMaterialAtlasesEvent.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) NeoForged and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.neoforged.neoforge.client.event;
+
+import java.util.Map;
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.renderer.texture.TextureAtlas;
+import net.minecraft.client.resources.TextureAtlasHolder;
+import net.minecraft.client.resources.model.Material;
+import net.minecraft.client.resources.model.ModelManager;
+import net.minecraft.resources.ResourceLocation;
+import net.neoforged.bus.api.Event;
+import net.neoforged.bus.api.ICancellableEvent;
+import net.neoforged.fml.LogicalSide;
+import net.neoforged.fml.event.IModBusEvent;
+import org.jetbrains.annotations.ApiStatus;
+
+/**
+ * Fired for registering {@linkplain TextureAtlas texture atlases} that will be used with {@link Material} or
+ * other systems which retrieve the atlas via {@link Minecraft#getTextureAtlas(ResourceLocation)} or
+ * {@link ModelManager#getAtlas(ResourceLocation)}.
+ * <p>
+ * If an atlas is registered via this event, then it must <b>NOT</b> be used through a {@link TextureAtlasHolder}.
+ * <p>
+ * This event fires during startup when the {@link ModelManager} is constructed.
+ * <p>
+ * This event is not {@linkplain ICancellableEvent cancellable}.
+ * <p>
+ * This event is fired on the mod-specific event bus, only on the {@linkplain LogicalSide#CLIENT logical client}.
+ */
+public class RegisterMaterialAtlasesEvent extends Event implements IModBusEvent {
+    private final Map<ResourceLocation, ResourceLocation> atlases;
+
+    @ApiStatus.Internal
+    public RegisterMaterialAtlasesEvent(Map<ResourceLocation, ResourceLocation> atlases) {
+        this.atlases = atlases;
+    }
+
+    /**
+     * Register a texture atlas with the given name and info location
+     * 
+     * @param atlasLocation     The name of the texture atlas
+     * @param atlasInfoLocation The location of the atlas info JSON relative to the {@code atlases} directory
+     */
+    public void register(ResourceLocation atlasLocation, ResourceLocation atlasInfoLocation) {
+        ResourceLocation oldAtlasInfoLoc = this.atlases.put(atlasLocation, atlasInfoLocation);
+        if (oldAtlasInfoLoc != null) {
+            throw new IllegalStateException(String.format(
+                    "Duplicate registration of atlas: %s (old info: %s, new info: %s)",
+                    atlasLocation,
+                    oldAtlasInfoLoc,
+                    atlasInfoLocation));
+        }
+    }
+}

tests/src/main/java/net/neoforged/neoforge/debug/client/TextureAtlasTests.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) NeoForged and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.neoforged.neoforge.debug.client;
+
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.renderer.texture.MissingTextureAtlasSprite;
+import net.minecraft.client.renderer.texture.TextureAtlasSprite;
+import net.minecraft.client.resources.model.Material;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.packs.resources.ResourceManagerReloadListener;
+import net.neoforged.api.distmarker.Dist;
+import net.neoforged.neoforge.client.event.RegisterClientReloadListenersEvent;
+import net.neoforged.neoforge.client.event.RegisterMaterialAtlasesEvent;
+import net.neoforged.testframework.DynamicTest;
+import net.neoforged.testframework.annotation.ForEachTest;
+import net.neoforged.testframework.annotation.TestHolder;
+
+@ForEachTest(side = Dist.CLIENT, groups = { "client.texture_atlas", "texture_atlas" })
+public class TextureAtlasTests {
+    @TestHolder(description = { "Tests that texture atlases intended for use with Material are correctly registered and loaded" }, enabledByDefault = true)
+    static void testMaterialAtlas(final DynamicTest test) {
+        String modId = test.createModId();
+        ResourceLocation atlasLoc = ResourceLocation.fromNamespaceAndPath(modId, "textures/atlas/material_test.png");
+
+        test.framework().modEventBus().addListener(RegisterMaterialAtlasesEvent.class, event -> {
+            ResourceLocation infoLoc = ResourceLocation.fromNamespaceAndPath(modId, "material_test");
+            event.register(atlasLoc, infoLoc);
+        });
+
+        test.framework().modEventBus().addListener(RegisterClientReloadListenersEvent.class, event -> {
+            event.registerReloadListener((ResourceManagerReloadListener) manager -> {
+                try {
+                    Minecraft.getInstance().getModelManager().getAtlas(atlasLoc);
+                } catch (NullPointerException npe) {
+                    test.fail("Atlas was not registered");
+                    return;
+                } catch (Throwable t) {
+                    test.fail("Atlas lookup failed: " + t.getMessage());
+                    return;
+                }
+
+                try {
+                    Material material = new Material(atlasLoc, ResourceLocation.withDefaultNamespace("block/stone"));
+                    TextureAtlasSprite sprite = material.sprite();
+                    if (sprite.contents().name().equals(MissingTextureAtlasSprite.getLocation())) {
+                        test.fail("Expected sprite was not stitched");
+                        return;
+                    }
+                } catch (Throwable t) {
+                    test.fail("Sprite lookup via material failed: " + t.getMessage());
+                }
+
+                test.pass();
+            });
+        });
+    }
+}

tests/src/main/resources/assets/neotests_test_material_atlas/atlases/material_test.json

@@ -0,0 +1,8 @@
+{
+    "sources": [
+        {
+            "type": "minecraft:single",
+            "resource": "minecraft:block/stone"
+        }
+    ]
+}