Render 2D texture in GUI for Geo Items (Fabric Only)

Thanks to MrSterner for this tip

This guide will cover rendering an item with a 2d in the GUI and creating a custom renderer.

Override renderInGui in Your Item Renderer

You need to override the renderInGui method for your item renderer and leave it empty. This method will be used in your GeoItem#createRenderer method.

@Override
protected void renderInGui(ModelTransformationMode transformType, MatrixStack matrixStack, VertexConsumerProvider bufferSource, int packedLight, int packedOverlay) {
    // No custom rendering code here
}

Create a Custom Renderer

Create a class that implements BuiltinItemRendererRegistry.DynamicItemRenderer and IdentifiableResourceReloadListener. This class will handle the rendering of your item in the GUI.

public class TwoDItemRenderer implements BuiltinItemRendererRegistry.DynamicItemRenderer, IdentifiableResourceReloadListener {
    private final Identifier id;
    private final Identifier itemId;
    private ItemRenderer itemRenderer;
    private BakedModel inventoryModel;

    public TwoDItemRenderer(Identifier itemId) {
        this.id = new Identifier(itemId.getNamespace(), itemId.getPath() + "_renderer");
        this.itemId = itemId;
    }

    @Override
    public CompletableFuture<Void> reload(Synchronizer synchronizer, ResourceManager manager, Profiler prepareProfiler, Profiler applyProfiler, Executor prepareExecutor, Executor applyExecutor) {
        return synchronizer.whenPrepared(Unit.INSTANCE).thenRunAsync(() -> {
            applyProfiler.startTick();
            applyProfiler.push("listener");
            final MinecraftClient client = MinecraftClient.getInstance();
            this.itemRenderer = client.getItemRenderer();
            this.inventoryModel = client.getBakedModelManager().getModel(new ModelIdentifier(itemId.withPath(itemId.getPath() + "_gui"), "inventory"));
            applyProfiler.pop();
            applyProfiler.endTick();
        }, applyExecutor);
    }

    @Override
    public void render(ItemStack stack, ModelTransformationMode mode, MatrixStack matrices, VertexConsumerProvider vertexConsumers, int light, int overlay) {
        matrices.pop();
        matrices.push();
        if (mode != ModelTransformationMode.FIRST_PERSON_LEFT_HAND && mode != ModelTransformationMode.FIRST_PERSON_RIGHT_HAND && mode != ModelTransformationMode.THIRD_PERSON_LEFT_HAND && mode != ModelTransformationMode.THIRD_PERSON_RIGHT_HAND) {
            if (this.itemRenderer == null) {
                this.itemRenderer = MinecraftClient.getInstance().getItemRenderer();
            }
            if (this.inventoryModel == null) {
                this.inventoryModel = MinecraftClient.getInstance().getBakedModelManager().getModel(new ModelIdentifier(itemId.withPath(itemId.getPath() + "_gui"), "inventory"));
            }
            DiffuseLighting.enableGuiDepthLighting();
            renderItem(itemRenderer, stack, mode, false, matrices, vertexConsumers, CAVUtils.MAX_LIGHT, overlay, this.inventoryModel);
            DiffuseLighting.disableGuiDepthLighting();
        }
    }

    public void renderItem(ItemRenderer itemRenderer, ItemStack stack, ModelTransformationMode renderMode, boolean leftHanded, MatrixStack matrices, VertexConsumerProvider vertexConsumers, int light, int overlay, BakedModel model) {
        if (!stack.isEmpty()) {
            matrices.push();

            model.getTransformation().getTransformation(renderMode).apply(leftHanded, matrices);
            matrices.translate(-0.5F, -0.5F, -0.5F);
            if (!model.isBuiltin()) {
                RenderLayer renderLayer = RenderLayers.getItemLayer(stack, true);
                VertexConsumer vertexConsumer = ItemRenderer.getDirectItemGlintConsumer(vertexConsumers, renderLayer, true, stack.hasGlint());

                itemRenderer.renderBakedItemModel(model, stack, light, overlay, matrices, vertexConsumer);
            }

            matrices.pop();
        }
    }

    @Override
    public Identifier getFabricId() {
        return id;
    }
}

Register the Renderer

Register your custom renderer and model reloading on the client side.

static void registerRenderer(Item item) {
    Identifier itemId = Registries.ITEM.getId(item);
    var renderer = new TwoDItemRenderer(itemId);
    ResourceManagerHelper.get(ResourceType.CLIENT_RESOURCES).registerReloadListener((IdentifiableResourceReloadListener) renderer);
    BuiltinItemRendererRegistry.INSTANCE.register(item, (BuiltinItemRendererRegistry.DynamicItemRenderer) renderer);
    ModelLoadingRegistry.INSTANCE.registerModelProvider((manager, out) -> {
        out.accept(new ModelIdentifier(itemId.withPath(itemId.getPath() + "_handheld"), "inventory"));
        out.accept(new ModelIdentifier(itemId.withPath(itemId.getPath() + "_gui"), "inventory"));
    });
}

Mixin to ItemRenderer

Use a mixin to override the getModel method in the ItemRenderer class to use your custom model.

@Mixin(ItemRenderer.class)
public class ItemRendererMixin {
    @Shadow
    @Final
    private ItemModels models;

    @Inject(method = "getModel", at = @At("HEAD"), cancellable = true)
    private void cav$getHeldItemModel(ItemStack stack, World world, LivingEntity entity, int seed, CallbackInfoReturnable<BakedModel> cir) {
        if (stack.getItem() instanceof YourCoolGeoDualModelItem) {
            Identifier itemId = Registries.ITEM.getId(stack.getItem());
            var m = new ModelIdentifier(itemId.withPath(itemId.getPath() + "_handheld"), "inventory");
            BakedModel bakedModel = models.getModelManager().getModel(m);
            ClientWorld clientWorld = world instanceof ClientWorld ? (ClientWorld) world : null;
            BakedModel bakedModel2 = bakedModel.getOverrides().apply(bakedModel, stack, clientWorld, entity, seed);
            cir.setReturnValue(bakedModel2 == null ? this.models.getModelManager().getMissingModel() : bakedModel2);
        }
    }
}

Creating Model JSON Files

Create the necessary model files for your item.

models/item/blunderbuss_gui.json

{
  "parent": "item/generated",
  "textures": {
    "layer0": "modid:item/blunderbuss_item"
  }
}

models/item/blunderbuss_handheld.json

{
  "parent": "builtin/entity",
  "texture_size": [
    ...
  ],
  "display": {
    ...
  }
}

Note: Replace "modid:item/blunderbuss_item" and other placeholder values with actual values relevant to your mod.