Custom SRP 7.3 Raster Shadow Passes
Catlike Coding Unity details a Custom SRP 7.3 update that shifts shadow rendering toward Unity’s raster render passes in 6000.5.8f1. The key change is architectural: directional shadow drawing is separated from resource setup and global GPU state, then the work is split into two passes so the draw pass can use raster rendering while the data pass still relies on unsafe buffer writes.
That split matters because Unity still lacks RasterCommandBuffer.SetBufferData, so the tutorial keeps a temporary unsafe path for uploading cascade and matrix data. Once that API lands in a supported Unity version, the extra unsafe pass can be removed and the whole shadow pipeline can be cleaner and more graph-friendly.
The implementation also updates how the atlas is handled. Instead of treating the shadow atlas like a generic texture use, the raster pass declares it as a render attachment depth target, marks it for clearing through TextureDesc.clearBuffer, and uses AccessFlags.Write so Unity can take the efficient clear path before rendering.
For engine programmers, the practical takeaway is that modern render graph attachment management can simplify shadow passes, but only if you respect the current API gaps. The tutorial also shows a useful pattern for incremental migration: isolate data setup, keep rendering logic narrow, and swap in raster passes where the backend already supports them.
“There is currently no RasterCommandBuffer.SetBufferData method.”
- what
- Custom SRP 7.3 moves shadow drawing to raster render passes and splits data upload into a separate unsafe pass.
- who
- Catlike Coding Unity, working with Unity 6000.5.8f1 and the Custom SRP tutorial series.
- when
- Published as part of the Custom SRP 7.3 tutorial update, following Custom SRP 7.2.
- impact
- Engine developers can adopt render-graph raster attachments for shadows while waiting for RasterCommandBuffer.SetBufferData.
Cleaner pipeline, but blocked by missing API support
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