Why does my URP Full Screen Pass produce nothing?

Source must be Active Color (not Camera Color directly), Pass Material must be assigned, and Render Pass Event = After Rendering Post Processing. Mismatched Source returns blank.

Difference from Render Objects?

Full Screen Pass operates on entire scene color buffer; Render Objects re-renders specific layers. Use Full Screen for screen-space effects (vignette, distortion).

Pass material constraints?

Use Shader Graph with target Universal Full Screen Pass. Built-in shaders won't have the right vertex output.

Fix: URP Full Screen Pass Feature No Output

Quick answer: Source = Active Color. Pass Material assigned (Shader Graph with Full Screen Pass target). Event = After Rendering Post Processing.

Vignette material via Full Screen Pass renderer feature. Frame Debugger shows the pass but output is blank.

The Fix

URP Renderer → + Full Screen Pass:
  Pass Material:        M_Vignette
  Source:               Active Color
  Set Inverted Depth:   false
  Render Pass Event:    After Rendering Post Processing

Shader Graph (Full Screen target):
  Vertex output via SCREEN_POSITION
  Fragment samples _BlitTexture for input

Active Color binds the current camera color render target. Custom shader reads via _BlitTexture and outputs modified color.

Verifying

Vignette darkens edges. Frame Debugger shows the pass with non-zero output. Without Source set: blank or noise.

“Active Color. Right shader target. Effect lands.”

Related Issues

For Render Objects mask, see Render Objects. For RenderGraph custom pass, see RenderGraph.

Active Color. Material. Event right.