Write a Scriptable Render Pass in Compatibility Mode in URP

Note: Unity no longer develops or improves the rendering path that doesn’t use the render graph API. Use the render graph API instead when developing new graphics features. To use the instructions on this page, enable Compatibility Mode (Render Graph Disabled) in URP graphics settings (Project Settings > Graphics).

To create a Scriptable Render Pass in the Universal Render PipelineA series of operations that take the contents of a Scene, and displays them on a screen. Unity lets you choose from pre-built render pipelines, or write your own. More info
See in Glossary (URP), follow these steps:

1. Create a C# script that inherits the ScriptableRenderPass class. For example:

   using UnityEngine.Rendering;
   using UnityEngine.Rendering.Universal;
   
   public class ExampleRenderPass : ScriptableRenderPass
   {
   }
   

2. In the class, add variables for the materials and textures you use in the render pass.

   For example, the following code sets up a handle to a texture, and a descriptor to configure the texture.

   private RTHandle textureHandle;
   private RenderTextureDescriptor textureDescriptor;
   

3. Override the Configure method to set up the render pass. Unity calls this method before executing the render pass.

   For example:

   public override void Configure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescriptor)
   {
       //Set the texture size to be the same as the camera target size.
       textureDescriptor.width = cameraTextureDescriptor.width;
       textureDescriptor.height = cameraTextureDescriptor.height;
   
       //Check if the descriptor has changed, and reallocate the texture handle if necessary.
       RenderingUtils.ReAllocateIfNeeded(ref textureHandle, textureDescriptor);
   }
   

4. Override the Execute method with your rendering commands. Unity calls this method every frame, once for each cameraA component which creates an image of a particular viewpoint in your scene. The output is either drawn to the screen or captured as a texture. More info
   See in Glossary.

   For example:

   public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
   {
       // Get a CommandBuffer from pool
       CommandBuffer cmd = CommandBufferPool.Get();
   
       // Add rendering commands to the CommandBuffer
       ...
   
       // Execute the command buffer and release it back to the pool
       context.ExecuteCommandBuffer(cmd);
       CommandBufferPool.Release(cmd);
   }
   

Inject a render pass into the render loop

To inject a render pass into the render loop in Compatibility Mode, refer to the following:

• Use the RenderPipelineManager API
• Use a Scriptable Renderer Feature

For a complete example, refer to Example of a Scriptable Renderer Feature in Compatibility mode.

Additional resources

• Custom render pass workflow
• Writing custom shaders in URP