WIP: Automatically generate fake item asset entries for skyblock items

src/main/kotlin/events/CustomItemModelEvent.kt

@@ -18,6 +18,6 @@ data class CustomItemModelEvent(
 	}
 
 	fun overrideIfExists(overrideModel: Identifier) {
-		TODO()
+		this.overrideModel = overrideModel
 	}
 }

src/texturePacks/README.md

@@ -0,0 +1,13 @@
+<!--
+SPDX-FileCopyrightText: 2023 Linnea Gräf <nea@nea.moe>
+
+SPDX-License-Identifier: CC0-1.0
+-->
+
+# Technical Notes for the texture pack implementation
+
+Relevant classes:
+
+`ItemModelManager` can be used to select an `ItemModel`. This is done from the `ITEM_MODEL` component which is defaulted by the `Item` class.
+
+The list of available `ItemModel`s (as in `Identifier` -> `ItemModel` maps) is loaded by `BakedModelManager`. To this end, item models in particular are loaded from `ItemAssetsLoader#load`. Those `ItemAssets` are found in `assets/<ns>/items/` directly (not in the model folder) and can be used to select other models, similar to how predicates used to work

src/texturePacks/java/moe/nea/firmament/features/texturepack/CustomGlobalArmorOverrides.kt

@@ -107,7 +107,7 @@ object CustomGlobalArmorOverrides {
 			return model
 		} else if (layers != null) {
 			val idNumber = sentinelFirmRunning.incrementAndGet()
-			val identifier = Identifier.of("firmament:sentinel/$idNumber")
+			val identifier = Identifier.of("firmament:sentinel/armor/$idNumber")
 			val equipmentLayers = layers.map {
 				EquipmentModel.Layer(
 					it.identifier, if (it.tint) {

src/texturePacks/java/moe/nea/firmament/mixins/custommodels/ReplaceItemModelPatch.java

@@ -5,20 +5,46 @@ import com.llamalad7.mixinextras.injector.wrapoperation.Operation;
 import com.llamalad7.mixinextras.injector.wrapoperation.WrapOperation;
 import moe.nea.firmament.events.CustomItemModelEvent;
 import net.minecraft.client.item.ItemModelManager;
+import net.minecraft.client.render.item.model.ItemModel;
+import net.minecraft.client.render.item.model.MissingItemModel;
+import net.minecraft.client.render.model.BakedModelManager;
 import net.minecraft.component.ComponentType;
 import net.minecraft.item.ItemStack;
+import net.minecraft.util.Identifier;
+import org.spongepowered.asm.mixin.Final;
 import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.Unique;
 import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import java.util.function.Function;
 
 @Mixin(ItemModelManager.class)
 public class ReplaceItemModelPatch {
+	@Shadow
+	@Final
+	private Function<Identifier, ItemModel> modelGetter;
+
+	@Inject(method = "<init>", at = @At("TAIL"))
+	private void saveMissingModel(BakedModelManager bakedModelManager, CallbackInfo ci) {
+	}
+
+	@Unique
+	// TODO: Fix scissors
+	private boolean hasModel(Identifier identifier) {
+		return !(modelGetter.apply(identifier) instanceof MissingItemModel);
+	}
+
 	@WrapOperation(
 		method = "update(Lnet/minecraft/client/render/item/ItemRenderState;Lnet/minecraft/item/ItemStack;Lnet/minecraft/item/ModelTransformationMode;Lnet/minecraft/world/World;Lnet/minecraft/entity/LivingEntity;I)V",
 		at = @At(value = "INVOKE", target = "Lnet/minecraft/item/ItemStack;get(Lnet/minecraft/component/ComponentType;)Ljava/lang/Object;"))
 	private Object replaceItemModelByIdentifier(ItemStack instance, ComponentType componentType, Operation<Object> original) {
 		var override = CustomItemModelEvent.getModelIdentifier(instance);
-		if (override != null)
+		if (override != null && hasModel(override)) {
 			return override;
+		}
 		return original.call(instance, componentType);
 	}
 }

src/texturePacks/java/moe/nea/firmament/mixins/custommodels/SupplyFakeModelPatch.java

@@ -0,0 +1,79 @@
+package moe.nea.firmament.mixins.custommodels;
+
+import com.llamalad7.mixinextras.injector.ModifyReturnValue;
+import com.llamalad7.mixinextras.sugar.Local;
+import net.minecraft.client.item.ItemAsset;
+import net.minecraft.client.item.ItemAssetsLoader;
+import net.minecraft.client.render.item.model.BasicItemModel;
+import net.minecraft.resource.Resource;
+import net.minecraft.resource.ResourceManager;
+import net.minecraft.resource.ResourcePack;
+import net.minecraft.util.Identifier;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.Executor;
+import java.util.stream.Collector;
+import java.util.stream.Collectors;
+
+@Mixin(ItemAssetsLoader.class)
+public class SupplyFakeModelPatch {
+
+	@ModifyReturnValue(
+		method = "load",
+		at = @At("RETURN")
+	)
+	private static CompletableFuture<ItemAssetsLoader.Result> injectFakeGeneratedModels(
+		CompletableFuture<ItemAssetsLoader.Result> original,
+		@Local(argsOnly = true) ResourceManager resourceManager,
+		@Local(argsOnly = true) Executor executor
+	) {
+		return original.thenCompose(oldModels -> CompletableFuture.supplyAsync(() -> supplyExtraModels(resourceManager, oldModels), executor));
+	}
+
+	private static ItemAssetsLoader.Result supplyExtraModels(ResourceManager resourceManager, ItemAssetsLoader.Result oldModels) {
+		Map<Identifier, ItemAsset> newModels = new HashMap<>(oldModels.contents());
+		var resources = resourceManager.findResources(
+			"models/item",
+			id -> id.getNamespace().equals("firmskyblock")
+				      && id.getPath().endsWith(".json")
+				      && !id.getPath().substring("models/item/".length()).contains("/"));
+		for (Map.Entry<Identifier, Resource> model : resources.entrySet()) {
+			var resource = model.getValue();
+			var itemModelId = model.getKey().withPath(it -> it.substring("models/item/".length(), it.length() - ".json".length()));
+			// TODO: parse json file here and make use of it in order to generate predicate files.
+			var genericModelId = itemModelId.withPrefixedPath("item/");
+			if (resourceManager.getResource(itemModelId)
+			                   .map(Resource::getPack)
+			                   .map(it -> isResourcePackNewer(resourceManager, it, resource.getPack()))
+			                   .orElse(true)) {
+				newModels.put(itemModelId, new ItemAsset(
+					new BasicItemModel.Unbaked(genericModelId, List.of()),
+					new ItemAsset.Properties(true)
+				));
+			}
+		}
+		return new ItemAssetsLoader.Result(newModels);
+	}
+
+	private static boolean isResourcePackNewer(
+		ResourceManager manager,
+		ResourcePack null_, ResourcePack proposal) {
+		var pack = manager.streamResourcePacks()
+		                  .filter(it -> it == null_ || it == proposal)
+		                  .collect(findLast());
+		return pack.orElse(null) == proposal;
+	}
+
+	private static <T> Collector<T, ?, Optional<T>> findLast() {
+		return Collectors.reducing(Optional.empty(), Optional::of,
+		                           (left, right) -> right.isPresent() ? right : left);
+
+	}
+
+}