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Won't Fix
Votes
0
Found in
6000.4.0a3
Issue ID
UUM-121911
Regression
No
[VFX] Gradient Mapped With GPU Expression
Steps to reproduce:
- Import attached VFX in a scene, either HDRP or URP project
- Observe console error
Actual results:
Compilation error
```Shader error in 'Hidden/VFX/Repro_Gradient/Simple Loop/Render Quad': undeclared identifier 'attributes' at /(2475) (on d3d11)```
Expected results:
No compilation error, there are some known limitation regarding slot being evaluated on CPU (like submesh mask) but this one is a GPU evaluation.
Reproducible with versions: 6000.4.0a3 (and other to define)
Not reproducible with versions: N/A
Can’t test with versions: N/A
Tested on (OS): Windows
Notes:
- See [https://discussions.unity.com/t/vfx-graph-bug-unity-6-3-output-particle-unlit-quad-undeclared-identifier-attributes/1689214]
- This following case compiles and should have the same constraint: !image-2025-10-10-15-35-48-125.png|width=387,height=181!
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Resolution Note:
Thank you for reporting this issue. After review, we’ve determined it cannot be addressed in the short term due to performance constraints.
Enabling gradient selection based on particleId would require adding an extra interpolator between the vertex and fragment stages. Profiling indicates this could lead to a noticeable GPU performance drop.
As an alternative, we are investigating dynamic interpolator packing, which could improve overall performance while still allowing certain inputs to depend on particleId without incurring the same penalty in most cases.