BlockEntityRenderer

A BlockEntityRenderer, often abbreviated as BER, is used to render blocks in a way that cannot be represented with a static baked model (JSON, OBJ, others). For example, this could be used to dynamically render container contents of a chest-like block. A block entity renderer requires the block to have a BlockEntity, even if the block does not store any data otherwise.

To create a BER, create a class that inherits from BlockEntityRenderer. It takes a generic argument specifying the block's BlockEntity class, which is used as a parameter type in the BER's render method.

// Assumes the existence of MyBlockEntity as a subclass of BlockEntity.
public class MyBlockEntityRenderer implements BlockEntityRenderer<MyBlockEntity> {
    // Add the constructor parameter for the lambda below. You may also use it to get some context
    // to be stored in local fields, such as the entity renderer dispatcher, if needed.
    public MyBlockEntityRenderer(BlockEntityRendererProvider.Context context) {
    }
    
    // This method is called every frame in order to render the block entity. Parameters are:
    // - blockEntity:   The block entity instance being rendered. Uses the generic type passed to the super interface.
    // - partialTick:   The amount of time, in fractions of a tick (0.0 to 1.0), that has passed since the last tick.
    // - poseStack:     The pose stack to render to.
    // - bufferSource:  The buffer source to get vertex buffers from.
    // - packedLight:   The light value of the block entity.
    // - packedOverlay: The current overlay value of the block entity, usually OverlayTexture.NO_OVERLAY.
    @Override
    public void render(MyBlockEntity blockEntity, float partialTick, PoseStack stack, MultiBufferSource bufferSource, int packedLight, int packedOverlay) {
        // Do the rendering here.
    }
}

Only one BER may exist for a given BlockEntityType<?>. Therefore, values that are specific to a single block entity instance should be stored in that block entity instance, rather than the BER itself.

When you have created your BER, you must also register it to EntityRenderersEvent.RegisterRenderers, an event fired on the mod event bus:

@SubscribeEvent
public static void registerEntityRenderers(EntityRenderersEvent.RegisterRenderers event) {
    event.registerBlockEntityRenderer(
            // The block entity type to register the renderer for.
            MyBlockEntities.MY_BLOCK_ENTITY.get(),
            // A function of BlockEntityRendererProvider.Context to BlockEntityRenderer.
            MyBlockEntityRenderer::new
    );
}

In the event that you do not need the BER provider context in your BER, you can also remove the constructor:

public class MyBlockEntityRenderer implements BlockEntityRenderer<MyBlockEntity> {
    @Override
    public void render( /* ... */ ) { /* ... */ }
}

// In your event handler class
@SubscribeEvent
public static void registerEntityRenderers(EntityRenderersEvent.RegisterRenderers event) {
    event.registerBlockEntityRenderer(MyBlockEntities.MY_BLOCK_ENTITY.get(),
            // Pass the context to an empty (default) constructor call
            context -> new MyBlockEntityRenderer()
    );
}

Item Block Rendering

As not all block entities with renderers can be rendered using static models, you can create a special renderer to customize the item rendering process. This is done using SpecialModelRenderers. In these cases, both a special model renderer must be created to render the item correctly, and a corresponding registered special block model renderer for scenarios when a block is being rendered as an item (e.g., enderman carrying a block).

Please refer to the client item documentation for more information.