Add UnbakedModelDeserializer (#4321)

* Add UnbakedModelDeserializer

* Document UnbakedModelDeserializer

* Allow custom model types to be optional

* Update javadoc as per suggestion

Co-authored-by: Juuz <6596629+Juuxel@users.noreply.github.com>

---------

Co-authored-by: Juuz <6596629+Juuxel@users.noreply.github.com>

fabric-model-loading-api-v1/src/client/java/net/fabricmc/fabric/api/client/model/loading/v1/UnbakedModelDeserializer.java

@@ -0,0 +1,105 @@
+/*
+ * 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.loading.v1;
+
+import java.io.Reader;
+
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParseException;
+import org.jetbrains.annotations.Nullable;
+
+import net.minecraft.client.render.model.UnbakedModel;
+import net.minecraft.client.render.model.json.JsonUnbakedModel;
+import net.minecraft.client.render.model.json.ModelElement;
+import net.minecraft.client.render.model.json.ModelElementFace;
+import net.minecraft.client.render.model.json.ModelElementTexture;
+import net.minecraft.client.render.model.json.ModelTransformation;
+import net.minecraft.client.render.model.json.Transformation;
+import net.minecraft.util.Identifier;
+
+import net.fabricmc.fabric.impl.client.model.loading.UnbakedModelDeserializerRegistry;
+
+/**
+ * Allows creating custom unbaked models by overriding the parsing of JSON model files.
+ *
+ * <p>The format for custom unbaked models is as follows:
+ * <pre>{@code
+ * {
+ *     "fabric:type": "<identifier of the deserializer>",
+ *     // extra model data, dependent on the deserializer
+ * }
+ * }</pre>
+ *
+ * <p>Alternatively, {@code "fabric:type"} may be an object with the required string field {@code "id"}, specifying the
+ * identifier of the deserializer, and the optional boolean field {@code "optional"} with default {@code false},
+ * specifying whether the model should fail loading ({@code false}) or continue loading as a vanilla model
+ * ({@code true}) when the specified deserializer has not been registered.
+ *
+ * <p>All instances must be registered using {@link #register} for deserialization to work.
+ */
+public interface UnbakedModelDeserializer {
+	/**
+	 * Registers a custom model deserializer.
+	 *
+	 * @throws IllegalArgumentException if the deserializer is already registered
+	 */
+	static void register(Identifier id, UnbakedModelDeserializer deserializer) {
+		UnbakedModelDeserializerRegistry.register(id, deserializer);
+	}
+
+	/**
+	 * {@return the custom model deserializer registered with the given identifier, or {@code null} if there is no such
+	 * deserializer}
+	 */
+	@Nullable
+	static UnbakedModelDeserializer get(Identifier id) {
+		return UnbakedModelDeserializerRegistry.get(id);
+	}
+
+	/**
+	 * Deserializes an {@link UnbakedModel} from a {@link Reader}, respecting custom deserializers. Prefer using this
+	 * method to {@link JsonUnbakedModel#deserialize(Reader)}.
+	 */
+	static UnbakedModel deserialize(Reader reader) throws JsonParseException {
+		return UnbakedModelDeserializerRegistry.deserialize(reader);
+	}
+
+	/**
+	 * Deserialize an {@link UnbakedModel} given a {@link JsonObject} representing the entire model file.
+	 *
+	 * <p>The provided deserialization context is able to deserialize objects of the following types:
+	 * <ul>
+	 *     <li>{@link UnbakedModel}</li>
+	 *     <li>{@link ModelElement}</li>
+	 *     <li>{@link ModelElementFace}</li>
+	 *     <li>{@link ModelElementTexture}</li>
+	 *     <li>{@link Transformation}</li>
+	 *     <li>{@link ModelTransformation}</li>
+	 * </ul>
+	 *
+	 * <p>For example, to deserialize a nested {@link UnbakedModel}, use
+	 * {@code context.deserialize(nestedModelJson, UnbakedModel.class)}.
+	 *
+	 * <p>This method is allowed and encouraged to throw exceptions, as they will be caught and logged by the caller.
+	 *
+	 * @param jsonObject the JSON object representing the entire model file
+	 * @param context the deserialization context
+	 * @return the unbaked model
+	 */
+	UnbakedModel deserialize(JsonObject jsonObject, JsonDeserializationContext context);
+}

fabric-model-loading-api-v1/src/client/java/net/fabricmc/fabric/impl/client/model/loading/UnbakedModelDeserializerRegistry.java

@@ -0,0 +1,54 @@
+/*
+ * 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.impl.client.model.loading;
+
+import java.io.Reader;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+
+import com.google.gson.JsonParseException;
+
+import net.minecraft.client.render.model.UnbakedModel;
+import net.minecraft.util.Identifier;
+import net.minecraft.util.JsonHelper;
+
+import net.fabricmc.fabric.api.client.model.loading.v1.UnbakedModelDeserializer;
+import net.fabricmc.fabric.mixin.client.model.loading.JsonUnbakedModelAccessor;
+
+public class UnbakedModelDeserializerRegistry {
+	private static final Map<Identifier, UnbakedModelDeserializer> DESERIALIZERS = new HashMap<>();
+
+	public static void register(Identifier id, UnbakedModelDeserializer deserializer) {
+		Objects.requireNonNull(id, "id cannot be null");
+		Objects.requireNonNull(id, "deserializer cannot be null");
+
+		if (DESERIALIZERS.putIfAbsent(id, deserializer) != null) {
+			throw new IllegalArgumentException("UnbakedModelDeserializer with identifier '" + id + "' already registered");
+		}
+	}
+
+	public static UnbakedModelDeserializer get(Identifier id) {
+		Objects.requireNonNull(id, "id cannot be null");
+
+		return DESERIALIZERS.get(id);
+	}
+
+	public static UnbakedModel deserialize(Reader reader) throws JsonParseException {
+		return JsonHelper.deserialize(JsonUnbakedModelAccessor.fabric_getGson(), reader, UnbakedModel.class);
+	}
+}

fabric-model-loading-api-v1/src/client/java/net/fabricmc/fabric/impl/client/model/loading/UnbakedModelJsonDeserializer.java

@@ -0,0 +1,72 @@
+/*
+ * 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.impl.client.model.loading;
+
+import java.lang.reflect.Type;
+
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonDeserializer;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParseException;
+import com.google.gson.JsonSyntaxException;
+
+import net.minecraft.client.render.model.UnbakedModel;
+import net.minecraft.client.render.model.json.JsonUnbakedModel;
+import net.minecraft.util.Identifier;
+import net.minecraft.util.JsonHelper;
+
+import net.fabricmc.fabric.api.client.model.loading.v1.UnbakedModelDeserializer;
+
+public class UnbakedModelJsonDeserializer implements JsonDeserializer<UnbakedModel> {
+	private static final String TYPE_KEY = "fabric:type";
+	private static final String TYPE_ID_KEY = "id";
+	private static final String TYPE_OPTIONAL_KEY = "optional";
+
+	@Override
+	public UnbakedModel deserialize(JsonElement jsonElement, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+		JsonObject jsonObject = jsonElement.getAsJsonObject();
+
+		if (jsonObject.has(TYPE_KEY)) {
+			JsonElement typeElement = jsonObject.get(TYPE_KEY);
+			String idStr;
+			boolean optional;
+
+			if (typeElement.isJsonPrimitive()) {
+				idStr = typeElement.getAsString();
+				optional = false;
+			} else if (typeElement.isJsonObject()) {
+				JsonObject typeObject = typeElement.getAsJsonObject();
+				idStr = JsonHelper.getString(typeObject, TYPE_ID_KEY);
+				optional = JsonHelper.getBoolean(typeObject, TYPE_OPTIONAL_KEY, false);
+			} else {
+				throw new JsonSyntaxException("Expected " + TYPE_KEY + " to be a string or object, was " + JsonHelper.getType(typeElement));
+			}
+
+			Identifier id = Identifier.of(idStr);
+			UnbakedModelDeserializer deserializer = UnbakedModelDeserializer.get(id);
+
+			if (deserializer != null) {
+				return deserializer.deserialize(jsonObject, context);
+			} else if (!optional) {
+				throw new JsonParseException("Cannot deserialize custom unbaked model of unknown type '" + id + "'");
+			}
+		}
+
+		return context.deserialize(jsonElement, JsonUnbakedModel.class);
+	}
+}

fabric-model-loading-api-v1/src/client/java/net/fabricmc/fabric/mixin/client/model/loading/BakedModelManagerMixin.java

@@ -16,6 +16,7 @@
 
 package net.fabricmc.fabric.mixin.client.model.loading;
 
+import java.io.Reader;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executor;
@@ -32,6 +33,7 @@
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.ModifyArg;
+import org.spongepowered.asm.mixin.injection.Redirect;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 
@@ -40,11 +42,13 @@
 import net.minecraft.client.render.model.BlockStatesLoader;
 import net.minecraft.client.render.model.ModelBaker;
 import net.minecraft.client.render.model.ReferencedModelsCollector;
+import net.minecraft.client.render.model.json.JsonUnbakedModel;
 import net.minecraft.resource.ResourceManager;
 import net.minecraft.resource.ResourceReloader;
 import net.minecraft.util.Identifier;
 
 import net.fabricmc.fabric.api.client.model.loading.v1.FabricBakedModelManager;
+import net.fabricmc.fabric.api.client.model.loading.v1.UnbakedModelDeserializer;
 import net.fabricmc.fabric.impl.client.model.loading.BakedModelsHooks;
 import net.fabricmc.fabric.impl.client.model.loading.ModelLoadingEventDispatcher;
 import net.fabricmc.fabric.impl.client.model.loading.ModelLoadingPluginManager;
@@ -122,6 +126,23 @@ private Function<Void, Object> hookModelBaking(Function<Void, Object> function)
 		};
 	}
 
+	// We want to redirect the JsonUnbakedModel.deserialize call, but its return type is JsonUnbakedModel, so we can't
+	// do that directly.
+	// Instead, cancel the original call and then modify the null value when it's being used to construct the Pair.
+	@Redirect(method = "method_65750(Ljava/util/Map$Entry;)Lcom/mojang/datafixers/util/Pair;", at = @At(value = "INVOKE", target = "net/minecraft/client/render/model/json/JsonUnbakedModel.deserialize(Ljava/io/Reader;)Lnet/minecraft/client/render/model/json/JsonUnbakedModel;"))
+	private static JsonUnbakedModel cancelVanillaDeserialize(Reader reader) {
+		return null;
+	}
+
+	// Here we replace the null model with one produced by our own deserializer.
+	// The Pair's type is actually Pair<Identifier, JsonUnbakedModel>, but since generics don't really exist, vanilla
+	// code doesn't explicitly cast the model to JsonUnbakedModel, and the enclosing method returns UnbakedModels per
+	// its return type, it's safe to return an UnbakedModel here.
+	@ModifyArg(method = "method_65750(Ljava/util/Map$Entry;)Lcom/mojang/datafixers/util/Pair;", at = @At(value = "INVOKE", target = "com/mojang/datafixers/util/Pair.of(Ljava/lang/Object;Ljava/lang/Object;)Lcom/mojang/datafixers/util/Pair;", remap = false), index = 1)
+	private static Object actuallyDeserializeModel(Object originalModel, @Local Reader reader) {
+		return UnbakedModelDeserializer.deserialize(reader);
+	}
+
 	@Inject(method = "upload", at = @At(value = "INVOKE_STRING", target = "net/minecraft/util/profiler/Profiler.swap(Ljava/lang/String;)V", args = "ldc=cache"))
 	private void onUpload(CallbackInfo ci, @Local ModelBaker.BakedModels bakedModels) {
 		extraModels = ((BakedModelsHooks) (Object) bakedModels).fabric_getExtraModels();

fabric-model-loading-api-v1/src/client/java/net/fabricmc/fabric/mixin/client/model/loading/JsonUnbakedModelAccessor.java

@@ -0,0 +1,31 @@
+/*
+ * 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.mixin.client.model.loading;
+
+import com.google.gson.Gson;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Accessor;
+
+import net.minecraft.client.render.model.json.JsonUnbakedModel;
+
+@Mixin(JsonUnbakedModel.class)
+public interface JsonUnbakedModelAccessor {
+	@Accessor("GSON")
+	static Gson fabric_getGson() {
+		throw new AssertionError();
+	}
+}

fabric-model-loading-api-v1/src/client/java/net/fabricmc/fabric/mixin/client/model/loading/JsonUnbakedModelMixin.java

@@ -0,0 +1,35 @@
+/*
+ * 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.mixin.client.model.loading;
+
+import com.google.gson.GsonBuilder;
+import com.llamalad7.mixinextras.injector.ModifyExpressionValue;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+
+import net.minecraft.client.render.model.UnbakedModel;
+import net.minecraft.client.render.model.json.JsonUnbakedModel;
+
+import net.fabricmc.fabric.impl.client.model.loading.UnbakedModelJsonDeserializer;
+
+@Mixin(JsonUnbakedModel.class)
+abstract class JsonUnbakedModelMixin {
+	@ModifyExpressionValue(method = "<clinit>()V", at = @At(value = "NEW", target = "com/google/gson/GsonBuilder", remap = false))
+	private static GsonBuilder addUnbakedModelAdapter(GsonBuilder builder) {
+		return builder.registerTypeHierarchyAdapter(UnbakedModel.class, new UnbakedModelJsonDeserializer());
+	}
+}

fabric-model-loading-api-v1/src/client/resources/fabric-model-loading-api-v1.mixins.json

@@ -4,6 +4,8 @@
   "compatibilityLevel": "JAVA_21",
   "client": [
     "BakedModelManagerMixin",
+    "JsonUnbakedModelAccessor",
+    "JsonUnbakedModelMixin",
     "ModelBakerBakedModelsMixin",
     "ModelBakerBakerImplMixin",
     "ModelBakerMixin",