Injection points
URP contains multiple injection points that let you inject render passes into the frame rendering loop and execute them upon different events.
Injection points give a custom render pass access to URP buffers. A render pass has read and write access to all buffers at each injection point.
Unity provides the following events in the rendering loop. You can use these events to inject your custom passes.
| Injection point | Description |
|---|---|
| BeforeRendering | Executes a ScriptableRenderPass instance before rendering any other passes in the pipeline for the current Camera. Camera matrices and stereo rendering are not setup at this point. You can use this injection point to draw to custom input textures used later in the pipeline, for example, LUT textures. |
| BeforeRenderingShadows | Executes a ScriptableRenderPass instance before rendering shadow maps (MainLightShadow, AdditionalLightsShadow passes).Camera matrices and stereo rendering are not set up at this point. |
| AfterRenderingShadows | Executes a ScriptableRenderPass instance after rendering shadow maps (MainLightShadow, AdditionalLightsShadow passes).Camera matrices and stereo rendering are not set up this point. |
| BeforeRenderingPrePasses | Executes a ScriptableRenderPass instance before rendering prepasses (DepthPrepass, DepthNormalPrepass passes).Camera matrices and stereo rendering are already set up at this point. |
| AfterRenderingPrePasses | Executes a ScriptableRenderPass instance after rendering prepasses (DepthPrepass, DepthNormalPrepass passes).Camera matrices and stereo rendering are set up at this point. |
| BeforeRenderingGbuffer | Executes a ScriptableRenderPass instance before rendering the GBuffer pass. |
| AfterRenderingGbuffer | Executes a ScriptableRenderPass instance after rendering the GBuffer pass. |
| BeforeRenderingDeferredLights | Executes a ScriptableRenderPass instance before rendering the Deferred pass. |
| AfterRenderingDeferredLights | Executes a ScriptableRenderPass instance after rendering the Deferred pass. |
| BeforeRenderingOpaques | Executes a ScriptableRenderPass instance before rendering opaque objects (DrawOpaqueObjects pass). |
| AfterRenderingOpaques | Executes a ScriptableRenderPass instance after rendering opaque objects (DrawOpaqueObjects pass). |
| BeforeRenderingSkybox | Executes a ScriptableRenderPass instance before rendering the skybox (Camera.RenderSkybox pass). |
| AfterRenderingSkybox | Executes a ScriptableRenderPass instance after rendering the skybox (Camera.RenderSkybox pass). |
| BeforeRenderingTransparents | Executes a ScriptableRenderPass instance before rendering transparent objects (DrawTransparentObjects pass). |
| AfterRenderingTransparents | Executes a ScriptableRenderPass instance after rendering transparent objects (DrawTransparentObjects pass). |
| BeforeRenderingPostProcessing | Executes a ScriptableRenderPass instance before rendering post-processing effects (Render PostProcessing Effects pass). |
| AfterRenderingPostProcessing | Executes a ScriptableRenderPass instance after rendering post-processing effects but before the final blit, post-processing anti-aliasing effects, and color grading. |
| AfterRendering | Executes ScriptableRenderPass instance after rendering all other passes. |
The following diagram shows the passes and the flow of frame resources in a URP frame:
