Provide replacement for ModelAppender that allows loading non-blockstate paths (#1178)

* Extend ModelAppender to allow loading non-blockstate paths

* Use a new interface instead of adding to the old one

* Rename new interface

(cherry picked from commit 6bec8f284f)

fabric-models-v0/src/main/java/net/fabricmc/fabric/api/client/model/ExtraModelProvider.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.api.client.model;
+
+import java.util.function.Consumer;
+
+import net.minecraft.client.util.ModelIdentifier;
+import net.minecraft.resource.ResourceManager;
+import net.minecraft.util.Identifier;
+
+@FunctionalInterface
+public interface ExtraModelProvider {
+	/**
+	 * Provides an opportunity inform the game that you would like it to load and bake a model,
+	 * even if that model is not used by any blocks or items.
+	 * @param out Accepts paths to be loaded. Arguments that are {@link ModelIdentifier} will be
+	 *            loaded through the blockstate JSON system or, if the variant is {@code inventory}, the item model folder.
+	 *            Otherwise, the argument is directly loaded as a JSON.
+	 *            For example, <pre>new Identifier("mymod", "foo/bar")</pre> will request loading of the file
+	 *            <pre>/assets/mymod/models/foo/bar.json</pre>
+	 */
+	void provideExtraModels(ResourceManager manager, Consumer<Identifier> out);
+}

fabric-models-v0/src/main/java/net/fabricmc/fabric/api/client/model/ModelAppender.java

@@ -20,8 +20,14 @@ import java.util.function.Consumer;
 
 import net.minecraft.client.util.ModelIdentifier;
 import net.minecraft.resource.ResourceManager;
+import net.minecraft.util.Identifier;
 
+/**
+ * @deprecated use {@link ExtraModelProvider}, which supports loading of plain {@link Identifier}s
+ */
+@Deprecated
 @FunctionalInterface
 public interface ModelAppender {
+	@Deprecated
 	void appendAll(ResourceManager manager, Consumer<ModelIdentifier> out);
 }

fabric-models-v0/src/main/java/net/fabricmc/fabric/api/client/model/ModelLoadingRegistry.java

@@ -19,6 +19,7 @@ package net.fabricmc.fabric.api.client.model;
 import java.util.function.Function;
 
 import net.minecraft.resource.ResourceManager;
+import net.minecraft.util.Identifier;
 
 import net.fabricmc.fabric.impl.client.model.ModelLoadingRegistryImpl;
 
@@ -26,10 +27,16 @@ public interface ModelLoadingRegistry {
 	ModelLoadingRegistry INSTANCE = ModelLoadingRegistryImpl.INSTANCE;
 
 	/**
-	 * Register a model appender, which can request loading additional models.
-	 *
-	 * @param appender
+	 * Register a model provider, which can request loading additional models.
+	 * @see ExtraModelProvider
 	 */
+	void registerModelProvider(ExtraModelProvider appender);
+
+	/**
+	 * Register a model appender, which can request loading additional models.
+	 * @deprecated Use {@link #registerModelProvider(ExtraModelProvider)} instead, which supports loading of plain {@link Identifier}s
+	 */
+	@Deprecated
 	void registerAppender(ModelAppender appender);
 
 	/**

fabric-models-v0/src/main/java/net/fabricmc/fabric/impl/client/model/ModelLoaderHooks.java

@@ -17,11 +17,10 @@
 package net.fabricmc.fabric.impl.client.model;
 
 import net.minecraft.client.render.model.UnbakedModel;
-import net.minecraft.client.util.ModelIdentifier;
 import net.minecraft.util.Identifier;
 
 public interface ModelLoaderHooks {
-	void fabric_addModel(ModelIdentifier id);
+	void fabric_addModel(Identifier id);
 
 	UnbakedModel fabric_loadModel(Identifier id);
 }

fabric-models-v0/src/main/java/net/fabricmc/fabric/impl/client/model/ModelLoadingRegistryImpl.java

@@ -35,6 +35,7 @@ import net.minecraft.client.util.ModelIdentifier;
 import net.minecraft.resource.ResourceManager;
 import net.minecraft.util.Identifier;
 
+import net.fabricmc.fabric.api.client.model.ExtraModelProvider;
 import net.fabricmc.fabric.api.client.model.ModelAppender;
 import net.fabricmc.fabric.api.client.model.ModelLoadingRegistry;
 import net.fabricmc.fabric.api.client.model.ModelProviderContext;
@@ -57,7 +58,7 @@ public class ModelLoadingRegistryImpl implements ModelLoadingRegistry {
 		private final ResourceManager manager;
 		private final List<ModelVariantProvider> modelVariantProviders;
 		private final List<ModelResourceProvider> modelResourceProviders;
-		private final List<ModelAppender> modelAppenders;
+		private final List<ExtraModelProvider> modelAppenders;
 		private ModelLoader loader;
 
 		private LoaderInstance(ModelLoadingRegistryImpl i, ModelLoader loader, ResourceManager manager) {
@@ -78,9 +79,9 @@ public class ModelLoadingRegistryImpl implements ModelLoadingRegistry {
 			return ((ModelLoaderHooks) loader).fabric_loadModel(id);
 		}
 
-		public void onModelPopulation(Consumer<ModelIdentifier> addModel) {
-			for (ModelAppender appender : modelAppenders) {
-				appender.appendAll(manager, addModel);
+		public void onModelPopulation(Consumer<Identifier> addModel) {
+			for (ExtraModelProvider appender : modelAppenders) {
+				appender.provideExtraModels(manager, addModel);
 			}
 		}
 
@@ -181,11 +182,16 @@ public class ModelLoadingRegistryImpl implements ModelLoadingRegistry {
 
 	private final List<Function<ResourceManager, ModelVariantProvider>> variantProviderSuppliers = new ArrayList<>();
 	private final List<Function<ResourceManager, ModelResourceProvider>> resourceProviderSuppliers = new ArrayList<>();
-	private final List<ModelAppender> appenders = new ArrayList<>();
+	private final List<ExtraModelProvider> appenders = new ArrayList<>();
+
+	@Override
+	public void registerModelProvider(ExtraModelProvider appender) {
+		appenders.add(appender);
+	}
 
 	@Override
 	public void registerAppender(ModelAppender appender) {
-		appenders.add(appender);
+		registerModelProvider((manager, consumer) -> appender.appendAll(manager, consumer::accept));
 	}
 
 	@Override

fabric-models-v0/src/main/java/net/fabricmc/fabric/mixin/client/model/MixinModelLoader.java

@@ -19,6 +19,7 @@ package net.fabricmc.fabric.mixin.client.model;
 import java.util.Map;
 import java.util.Set;
 
+import org.spongepowered.asm.mixin.Final;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.injection.At;
@@ -35,7 +36,7 @@ import net.fabricmc.fabric.impl.client.model.ModelLoaderHooks;
 import net.fabricmc.fabric.impl.client.model.ModelLoadingRegistryImpl;
 
 @Mixin(ModelLoader.class)
-public class MixinModelLoader implements ModelLoaderHooks {
+public abstract class MixinModelLoader implements ModelLoaderHooks {
 	// this is the first one
 	@Shadow
 	public static ModelIdentifier MISSING;
@@ -45,6 +46,9 @@ public class MixinModelLoader implements ModelLoaderHooks {
 	private Set<Identifier> modelsToLoad;
 	@Shadow
 	private Map<Identifier, UnbakedModel> unbakedModels;
+	@Shadow
+	@Final
+	private Map<Identifier, UnbakedModel> modelsToBake;
 
 	private ModelLoadingRegistryImpl.LoaderInstance fabric_mlrLoaderInstance;
 
@@ -57,6 +61,8 @@ public class MixinModelLoader implements ModelLoaderHooks {
 	@Shadow
 	private void loadModel(Identifier id) { }
 
+	@Shadow public abstract UnbakedModel getOrLoadModel(Identifier id);
+
 	@Inject(at = @At("HEAD"), method = "loadModel", cancellable = true)
 	private void loadModelHook(Identifier id, CallbackInfo ci) {
 		UnbakedModel customModel = fabric_mlrLoaderInstance.loadModelFromVariant(id);
@@ -85,8 +91,17 @@ public class MixinModelLoader implements ModelLoaderHooks {
 	}
 
 	@Override
-	public void fabric_addModel(ModelIdentifier id) {
-		addModel(id);
+	public void fabric_addModel(Identifier id) {
+		if (id instanceof ModelIdentifier) {
+			addModel((ModelIdentifier) id);
+		} else {
+			// The vanilla addModel method is arbitrarily limited to ModelIdentifiers,
+			// but it's useful to tell the game to just load and bake a direct model path as well.
+			// Replicate the vanilla logic of addModel here.
+			UnbakedModel unbakedModel = getOrLoadModel(id);
+			this.unbakedModels.put(id, unbakedModel);
+			this.modelsToBake.put(id, unbakedModel);
+		}
 	}
 
 	@Override