Cut more chaff

src/main/java/io/github/cottonmc/templates/TemplatesModelProvider.java

@@ -0,0 +1,74 @@
+package io.github.cottonmc.templates;
+
+import net.fabricmc.fabric.api.client.model.ModelProviderContext;
+import net.fabricmc.fabric.api.client.model.ModelProviderException;
+import net.fabricmc.fabric.api.client.model.ModelResourceProvider;
+import net.fabricmc.fabric.api.client.model.ModelVariantProvider;
+import net.minecraft.client.render.model.UnbakedModel;
+import net.minecraft.client.util.ModelIdentifier;
+import net.minecraft.item.ItemConvertible;
+import net.minecraft.registry.Registries;
+import net.minecraft.util.Identifier;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Supplier;
+
+public class TemplatesModelProvider implements ModelResourceProvider, ModelVariantProvider {
+	private final Map<Identifier, Supplier<UnbakedModel>> factories = new HashMap<>();
+	private final Map<ModelIdentifier, Identifier> itemAssignments = new HashMap<>();
+	
+	private final Map<Identifier, UnbakedModel> cache = new HashMap<>();
+	
+	@Override
+	public @Nullable UnbakedModel loadModelResource(Identifier resourceId, ModelProviderContext context) throws ModelProviderException {
+		UnbakedModel cacheResult = cache.get(resourceId);
+		if(cacheResult != null) return cacheResult;
+		
+		//Either we have a factory for this model (just haven't cached its output yet),
+		Supplier<UnbakedModel> factory = factories.get(resourceId);
+		if(factory != null) {
+			UnbakedModel freshModel = factory.get();
+			cache.put(resourceId, freshModel);
+			return freshModel;
+		}
+		
+		//or we don't cover this model at all.
+		return null;
+	}
+	
+	//For blocks, you can point the game directly at the custom model in the blockstate json file.
+	//Item models don't have that layer of indirection; it always wants to load the hardcoded "item:id#inventory" model.
+	//You *would* be able to create a model json for it and set the "parent" field to the custom model,
+	//but json models are never allowed to have non-json models as a parent, and template unbaked models are not json models. Ah well.
+	//So, instead, we use a ModelVariantProvider to clunkily redirect the item:id#inventory model to the blockmodel.
+	//Not my favorite solution (for one, it precludes setting custom rotations in the item model) but we'll live.
+	@Override
+	public @Nullable UnbakedModel loadModelVariant(ModelIdentifier modelId, ModelProviderContext context) throws ModelProviderException {
+		Identifier customModelId = itemAssignments.get(modelId);
+		return customModelId == null ? null : loadModelResource(customModelId, context);
+	}
+	
+	// "public api"
+	
+	public void addTemplateModel(Identifier id, Supplier<UnbakedModel> modelFactory) {
+		factories.put(id, modelFactory);
+	}
+	
+	public void assignItemModel(Identifier templateModelId, ModelIdentifier... modelIds) {
+		for(ModelIdentifier modelId : modelIds) itemAssignments.put(modelId, templateModelId);
+	}
+	
+	public void assignItemModel(Identifier templateModelId, Identifier... itemIds) {
+		for(Identifier itemId : itemIds) itemAssignments.put(new ModelIdentifier(itemId, "inventory"), templateModelId);
+	}
+	
+	public void assignItemModel(Identifier templateModelId, ItemConvertible... itemConvs) {
+		for(ItemConvertible itemConv : itemConvs) assignItemModel(templateModelId, Registries.ITEM.getId(itemConv.asItem()));
+	}
+	
+	public void dumpCache() {
+		cache.clear();
+	}
+}