[FabricMC] Custom model overrides for Items depending on their ModelTransformationMode

README.md

This gist represents a skeleton structure for overriding Items depending on their ModelTransformationMode. All code is free to use, with no attribution needed.

NOTE: This code will NOT work for >= 1.20.4

1.21.* includes functionality similar to this natively

BooleanModelOverride.java

// Not required, but is very helpful.
@Environment(EnvType.CLIENT)
public class BooleanModelOverride implements ClampedModelPredicateProvider {
    public static ModelTransformationMode currentModelTransform = ModelTransformationMode.NONE;
    public static int offset = 1;
    int thisOffset = 0;
    public BooleanModelOverride(Function4<ItemStack, ClientWorld, LivingEntity, Integer, Boolean> p) {
        this.predicate = p;
        this.thisOffset = offset++;
    }
    public float execute(ItemStack s, ClientWorld w, LivingEntity e, int seed) {
        if (predicate == null) {return 0;}
        return predicate.apply(s, w, e, seed) ? 0.07991f * thisOffset : 0f;
    }

    public static boolean isRenderingInGUI(ItemStack stack) {
        return currentModelTransform == ModelTransformationMode.GUI && !isRenderingInHandAny(stack);
    }
    public static boolean isRenderingInHandFirst(ItemStack stack) {
        return currentModelTransform.isFirstPerson();
    }
    public static boolean isRenderingInHandThird(ItemStack stack) {
        return currentModelTransform == ModelTransformationMode.THIRD_PERSON_LEFT_HAND || currentModelTransform == ModelTransformationMode.THIRD_PERSON_RIGHT_HAND;
    }
    public static boolean isRenderingInHandAny(ItemStack stack) {
        return isRenderingInHandFirst(stack) || isRenderingInHandThird(stack);
    }
    public static boolean isRenderingInFixedPos(ItemStack stack) {
        return currentModelTransform == ModelTransformationMode.FIXED;
    }
    public static boolean isRenderingAsDropped(ItemStack stack) {
        return currentModelTransform == ModelTransformationMode.GROUND;
    }
    public final Function4<ItemStack, ClientWorld, LivingEntity, Integer, Boolean> predicate;

    @Override
    public float unclampedCall(ItemStack stack, @Nullable ClientWorld world, @Nullable LivingEntity entity, int seed) {
        return execute(stack, world, entity, seed);
    }
}

mixins_ItemRendererMixin.java

@Mixin(ItemRenderer.class)
public abstract class ItemRendererMixin {
    @ModifyArg(method="renderItem(Lnet/minecraft/item/ItemStack;Lnet/minecraft/client/render/model/json/ModelTransformationMode;ZLnet/minecraft/client/util/math/MatrixStack;Lnet/minecraft/client/render/VertexConsumerProvider;IILnet/minecraft/client/render/model/BakedModel;)V",
    at=@At(value="INVOKE", target = "Lnet/minecraft/client/render/item/ItemRenderer;renderBakedItemModel(Lnet/minecraft/client/render/model/BakedModel;Lnet/minecraft/item/ItemStack;IILnet/minecraft/client/util/math/MatrixStack;Lnet/minecraft/client/render/VertexConsumer;)V"))
    private BakedModel injectedModel(BakedModel model, @Local ItemStack stack, @Local MatrixStack matrixStack, @Local ModelTransformationMode mode, @Local VertexConsumerProvider consumerProvider) {
        var m =  model.getOverrides().apply(model,stack,MinecraftClient.getInstance().world, null,42);
        return m;
    }
    @Inject(at=@At("HEAD"), method= "renderItem(Lnet/minecraft/item/ItemStack;Lnet/minecraft/client/render/model/json/ModelTransformationMode;ZLnet/minecraft/client/util/math/MatrixStack;Lnet/minecraft/client/render/VertexConsumerProvider;IILnet/minecraft/client/render/model/BakedModel;)V")
    public void renderItem(ItemStack stack, ModelTransformationMode renderMode, boolean leftHanded, MatrixStack matrices, VertexConsumerProvider vertexConsumers, int light, int overlay, BakedModel model, CallbackInfo ci, @Share("model") LocalRef<BakedModel> modelRef) {
        BooleanModelOverride.currentModelTransform = renderMode;
    }
}

mixins_ModelOverrideDeserialzierMixin.java

@Environment(EnvType.CLIENT)
@Mixin(targets = "net.minecraft.client.render.model.json.ModelOverride$Deserializer")
public class ModelOverrideDeserializerMixin {


    /**
     * Calculate a 64 bits hash by combining CRC32 with Adler32.
     *
     * @param bytes a byte array
     * @return a hash number
     */
    public static long getHash64(byte[] bytes) {

        CRC32 crc32 = new CRC32();
        Adler32 adl32 = new Adler32();

        crc32.update(bytes);
        adl32.update(bytes);

        long crc = crc32.getValue();
        long adl = adl32.getValue();
        return ((crc << 32) | adl) + (crc << 8);
    }
    public static long getHash64(String s) {
        return getHash64(s.getBytes(StandardCharsets.UTF_8));
    }

    // Unfortunately, I need to do this to allow different types. Sorry!
    @Inject(method="deserializeMinPropertyValues", at=@At("HEAD"), cancellable = true)
    private void onDeserializeMinPropertyValues(JsonObject object, CallbackInfoReturnable<List<ModelOverride.Condition>> cir) {        List<ModelOverride.Condition> conds = new ArrayList<>();

        JsonObject jsonObject = JsonHelper.getObject(object, "predicate");
        for (Map.Entry<String, JsonElement> stringJsonElementEntry : jsonObject.entrySet()) {
            if (JsonHelper.isBoolean(stringJsonElementEntry.getValue())) {
                boolean s = JsonHelper.asBoolean(stringJsonElementEntry.getValue(), stringJsonElementEntry.getKey());
                float v = s ? 0.07991f : 0;
                conds.add(new ModelOverride.Condition(new Identifier(stringJsonElementEntry.getKey()), v));
                continue;
            } else if (JsonHelper.isString(stringJsonElementEntry.getValue())) {
                float v = getHash64(JsonHelper.asString(stringJsonElementEntry.getValue(), stringJsonElementEntry.getKey()));
                conds.add(new ModelOverride.Condition(new Identifier(stringJsonElementEntry.getKey()), v));
                continue;
            }
            conds.add(new ModelOverride.Condition(new Identifier(stringJsonElementEntry.getKey()), JsonHelper.asFloat(stringJsonElementEntry.getValue(), stringJsonElementEntry.getKey())));
            i++;
        }
        cir.setReturnValue (conds);
    }
}

ModInitializer.java

public void onInitializeClient() {
    ...
    ModelPredicateProviderRegistry.register(new Identifier("is_hand_first"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInHandFirst(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_hand_third"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInHandThird(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_hand_any"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInHandAny(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_in_hand_first"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInHandFirst(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_in_hand_third"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInHandThird(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_in_hand_any"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInHandAny(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_gui"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInGUI(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_inventory"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInGUI(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_fixed"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInFixedPos(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_in_gui"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInGUI(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_in_inventory"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInGUI(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_in_fixed"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInFixedPos(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_in_item_frame"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingInFixedPos(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_dropped"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingAsDropped(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_ground"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingAsDropped(itemStack)));
    ModelPredicateProviderRegistry.register(new Identifier("is_on_ground"), new BooleanModelOverride((itemStack, clientWorld, livingEntity, integer) -> BooleanModelOverride.isRenderingAsDropped(itemStack)));
}

my_custom_item.json

{
	"credit": "Made with Blockbench",
	"parent": "namespace:item/my_item",
	"gui_light": "front",
	"overrides": [
		{"predicate": {"is_gui": false, "is_hand_any": true, "swing_time": 0, "use_time": 0}, "model": "namespace:item/in_hand"},
		{"predicate": {"is_gui": false, "is_hand_any": true, "use_time": 0.001}, "model": "namespace:item/in_hand_using"},
		{"predicate": {"is_gui": false, "is_hand_any": true, "swing_time": 0.001, "use_time": 0}, "model": "namespace:item/in_hand_swinging"}
	]
}