Extending the Built-in Render Pipeline with Command Buffers

A Command Buffer holds a list of rendering commands. You can instruct Unity to schedule and execute those commands.

This page contains information on using Command Buffers in the Built-in Render Pipeline. For information on using Command Buffers in the Scriptable Rendering Pipeline, see Scheduling and executing rendering commands in the Scriptable Rendering Pipeline.

For a full list of the commands that you can execute using Command Buffers, see the CommandBuffer API documentation. Note that some commands are supported only on certain hardware; for example, the commands relating to ray tracing are supported only in DX12.

Executing Command Buffers immediately

You can execute Command Buffers immediately using the Graphics.ExecuteCommandBuffer API.

Scheduling Command Buffers

In the Built-in Render Pipeline, you can execute Command Buffers at specific times in the render loop; to do this, use the Camera.AddCommandBuffer API with the CameraEvent enum, and the Light.AddCommandBuffer API with the LightEvent enum.

For example, you can use a Command Buffer with the AfterGBuffer CameraEvent to render additional GameObjects into the Deferred pipeline, after the pipeline processes all opaque GameObjects.

CameraEvent order of execution

The order of execution depends on the rendering path that your Project uses.

LightEvent order of execution

During the “render shadows” stage above, for each shadow-casting Light, Unity performs these steps:

Additional resources

• The Unity blog post Extending Unity 5 rendering pipeline: Command Buffers introduces Command Buffers in the Built-in Render Pipeline, and contains a sample project and example code. It relates to an older version of Unity, but the principles are the same.