Add custom TextureAtlasSprite loaders (#7822)

Adds a system for mods to specify custom texture loaders which can be requested by the resource pack through a metadata section in the .mcmeta file. Due to technical reasons, png file is still required for MC to identify a texture as existing, even if the loader doesn't use it.

src/main/java/net/minecraftforge/client/ForgeHooksClient.java

@@ -61,6 +61,8 @@ import net.minecraft.fluid.FluidState;
 import net.minecraft.inventory.EquipmentSlotType;
 import net.minecraft.item.ItemStack;
 import net.minecraft.item.crafting.RecipeManager;
+import net.minecraft.resources.IResource;
+import net.minecraft.resources.IResourceManager;
 import net.minecraft.util.Direction;
 import net.minecraft.util.Hand;
 import net.minecraft.util.MovementInput;
@@ -84,6 +86,7 @@ import net.minecraftforge.client.event.*;
 import net.minecraftforge.client.event.sound.PlaySoundEvent;
 import net.minecraftforge.client.model.ModelLoader;
 import net.minecraftforge.client.model.animation.Animation;
+import net.minecraftforge.client.textures.ForgeTextureMetadata;
 import net.minecraftforge.common.ForgeMod;
 import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.common.model.TransformationHelper;
@@ -822,4 +825,18 @@ public class ForgeHooksClient
     {
         return Optional.of(ForgeWorldTypeScreens.getDefaultGenerator());
     }
+
+    @Nullable
+    public static TextureAtlasSprite loadTextureAtlasSprite(
+            AtlasTexture atlasTexture,
+            IResourceManager resourceManager, TextureAtlasSprite.Info textureInfo,
+            IResource resource,
+            int atlasWidth, int atlasHeight,
+            int spriteX, int spriteY, int mipmapLevel,
+            NativeImage image
+    )
+    {
+        ForgeTextureMetadata metadata = ForgeTextureMetadata.forResource(resource);
+        return metadata.getLoader() == null ? null : metadata.getLoader().load(atlasTexture, resourceManager, textureInfo, resource, atlasWidth, atlasHeight, spriteX, spriteY, mipmapLevel, image);
+    }
 }

src/main/java/net/minecraftforge/client/MinecraftForgeClient.java

@@ -23,7 +23,9 @@ import java.io.IOException;
 import java.util.BitSet;
 import java.util.HashMap;
 import java.util.Locale;
+import java.util.Map;
 import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Supplier;
 
@@ -45,6 +47,7 @@ import net.minecraft.resources.IResourceManager;
 import net.minecraft.util.ResourceLocation;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.World;
+import net.minecraftforge.client.textures.ITextureAtlasSpriteLoader;
 
 public class MinecraftForgeClient
 {
@@ -156,4 +159,21 @@ public class MinecraftForgeClient
         IResource iresource1 = resourceManager.getResource(resourceLocation);
         return NativeImage.read(iresource1.getInputStream());
     }
+
+    private static final Map<ResourceLocation, ITextureAtlasSpriteLoader> textureAtlasSpriteLoaders = new ConcurrentHashMap<>();
+
+    /**
+     * Register a custom ITextureAtlasSprite loader. Call this method during {@link net.minecraftforge.fml.event.lifecycle.FMLClientSetupEvent}.
+     */
+    public static void registerTextureAtlasSpriteLoader(ResourceLocation name, ITextureAtlasSpriteLoader loader)
+    {
+        textureAtlasSpriteLoaders.put(name, loader);
+    }
+
+    @Nullable
+    public static ITextureAtlasSpriteLoader getTextureAtlasSpriteLoader(ResourceLocation name)
+    {
+        return textureAtlasSpriteLoaders.get(name);
+    }
+
 }

src/main/java/net/minecraftforge/client/extensions/IForgeTextureAtlasSprite.java

@@ -30,34 +30,26 @@ import net.minecraft.util.ResourceLocation;
 
 public interface IForgeTextureAtlasSprite
 {
+
     /**
-     * The result of this function determines is the below 'load' function is called, and the
-     * default vanilla loading code is bypassed completely.
-     * @param manager Main resource manager
-     * @param location File resource location
-     * @return True to use your own custom load code and bypass vanilla loading.
+     * @deprecated See {@link net.minecraftforge.client.textures.ITextureAtlasSpriteLoader}
      */
+    @Deprecated
     default boolean hasCustomLoader(IResourceManager manager, ResourceLocation location)
     {
         return false;
     }
 
     /**
-     * Load the specified resource as this sprite's data.
-     * Returning false from this function will prevent this icon from being stitched onto the master texture.
-     * @param manager Main resource manager
-     * @param location File resource location
-     * @param textureGetter accessor for dependencies. All of them will be loaded before this one
-     * @return False to prevent this Icon from being stitched
+     * @deprecated See {@link net.minecraftforge.client.textures.ITextureAtlasSpriteLoader}
      */
+    @Deprecated
     default boolean load(IResourceManager manager, ResourceLocation location, Function<ResourceLocation, TextureAtlasSprite> textureGetter)
     {
         return true;
     }
 
-    /**
-     * @return all textures that should be loaded before this texture.
-     */
+    @Deprecated
     default Collection<ResourceLocation> getDependencies() 
     {
         return ImmutableList.of();

src/main/java/net/minecraftforge/client/textures/ForgeTextureMetadata.java

@@ -0,0 +1,98 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2021.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.client.textures;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+import net.minecraft.resources.IResource;
+import net.minecraft.resources.data.IMetadataSectionSerializer;
+import net.minecraft.util.JSONUtils;
+import net.minecraft.util.ResourceLocation;
+import net.minecraftforge.client.MinecraftForgeClient;
+
+import com.google.gson.JsonObject;
+import com.google.gson.JsonSyntaxException;
+
+/**
+ * The "forge" section of texture metadata files (.mcmeta). Currently used only to specify custom
+ * TextureAtlasSprite loaders.
+ * @see ITextureAtlasSpriteLoader
+ */
+public final class ForgeTextureMetadata
+{
+
+    public static final ForgeTextureMetadata EMPTY = new ForgeTextureMetadata(null);
+    public static final IMetadataSectionSerializer<ForgeTextureMetadata> SERIALIZER = new Serializer();
+
+    public static ForgeTextureMetadata forResource(IResource resource)
+    {
+        ForgeTextureMetadata metadata = resource.getMetadata(SERIALIZER);
+        return metadata == null ? EMPTY : metadata;
+    }
+
+    @Nullable
+    private final ITextureAtlasSpriteLoader loader;
+
+    public ForgeTextureMetadata(@Nullable ITextureAtlasSpriteLoader loader)
+    {
+        this.loader = loader;
+    }
+
+    @Nullable
+    public ITextureAtlasSpriteLoader getLoader()
+    {
+        return loader;
+    }
+
+    private static final class Serializer implements IMetadataSectionSerializer<ForgeTextureMetadata>
+    {
+
+        @Override
+        @Nonnull
+        public String getMetadataSectionName()
+        {
+            return "forge";
+        }
+
+        @Override
+        @Nonnull
+        public ForgeTextureMetadata fromJson(JsonObject json)
+        {
+            @Nullable
+            ITextureAtlasSpriteLoader loader;
+            if (json.has("loader"))
+            {
+                ResourceLocation loaderName = new ResourceLocation(JSONUtils.getAsString(json, "loader"));
+                loader = MinecraftForgeClient.getTextureAtlasSpriteLoader(loaderName);
+                if (loader == null)
+                {
+                    throw new JsonSyntaxException("Unknown TextureAtlasSpriteLoader " + loaderName);
+                }
+            }
+            else
+            {
+                loader = null;
+            }
+            return new ForgeTextureMetadata(loader);
+        }
+    }
+
+}

src/main/java/net/minecraftforge/client/textures/ITextureAtlasSpriteLoader.java

@@ -0,0 +1,59 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2021.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.client.textures;
+
+import javax.annotation.Nonnull;
+
+import net.minecraft.client.renderer.texture.AtlasTexture;
+import net.minecraft.client.renderer.texture.NativeImage;
+import net.minecraft.client.renderer.texture.TextureAtlasSprite;
+import net.minecraft.resources.IResource;
+import net.minecraft.resources.IResourceManager;
+import net.minecraft.util.ResourceLocation;
+
+/**
+ * A loader for custom TextureAtlasSprite implementations.<br>
+ * The loader can be specified in the corresponding .mcmeta file for a texture as follows:
+ * <pre>
+ * {
+ *   "forge": {
+ *     "loader": "examplemod:example_tas_loader"
+ *   }
+ * }
+ * </pre>
+ * @see net.minecraftforge.client.MinecraftForgeClient#registerTextureAtlasSpriteLoader(ResourceLocation, ITextureAtlasSpriteLoader)
+ */
+public interface ITextureAtlasSpriteLoader
+{
+
+    /**
+     * Load a TextureAtlasSprite for the given resource.
+     */
+    @Nonnull
+    TextureAtlasSprite load(
+            AtlasTexture atlas,
+            IResourceManager resourceManager, TextureAtlasSprite.Info textureInfo,
+            IResource resource,
+            int atlasWidth, int atlasHeight,
+            int spriteX, int spriteY, int mipmapLevel,
+            NativeImage image
+    );
+
+}