Alpha bug on Principaled BSDF with GPU #100291

Open
opened 2022-08-08 23:27:08 +02:00 by Mason · 7 comments

System Information
Operating system: Windows-10-10.0.19043-SP0 64 Bits
Graphics card: NVIDIA RTX A2000 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 512.92

Blender Version
Broken: version: 3.2.1, branch: master, commit date: 2022-07-05 15:44, hash: a2d59b2dac
Worked: (newest version of Blender that worked as expected)

Short description of error
Decreasing alpha makes material black in the Principaled BSDF shader when using GPU compared to CPU

Exact steps for others to reproduce the error

  • Decrease "Alpha" on the Principaled BSDF shader
  • Change to device to either "GPU Compute" or "CPU"
  • Adjust alpha value to discern difference if not apparent when switching Device property

Notes
CPU appears to work correctly with this value, it's only on GPU on my machine that causes alpha to make the material black. Bug appears in rendered images too and not just viewport, and is present in both CUDA and Optix.

Make my alpha 0% if duplicate.

Blender GPU Alpha Bug.blend

**System Information** Operating system: Windows-10-10.0.19043-SP0 64 Bits Graphics card: NVIDIA RTX A2000 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 512.92 **Blender Version** Broken: version: 3.2.1, branch: master, commit date: 2022-07-05 15:44, hash: `a2d59b2dac` Worked: (newest version of Blender that worked as expected) **Short description of error** Decreasing alpha makes material black in the Principaled BSDF shader when using GPU compared to CPU **Exact steps for others to reproduce the error** - Decrease "Alpha" on the Principaled BSDF shader - Change to device to either "GPU Compute" or "CPU" - Adjust alpha value to discern difference if not apparent when switching Device property **Notes** CPU appears to work correctly with this value, it's only on GPU on my machine that causes alpha to make the material black. Bug appears in rendered images too and not just viewport, and is present in both CUDA and Optix. Make my alpha 0% if duplicate. [Blender GPU Alpha Bug.blend](https://archive.blender.org/developer/F13346928/Blender_GPU_Alpha_Bug.blend)
Author

Added subscriber: @mrm-1

Added subscriber: @mrm-1

Added subscriber: @ThomasDinges

Added subscriber: @ThomasDinges

Cannot confirm the issue with AMD HIP rendering, decreasing the alpha works properly with both CPU and GPU. Tested with Blender 3.2.2 and 3.3 Beta.

Cannot confirm the issue with AMD HIP rendering, decreasing the alpha works properly with both CPU and GPU. Tested with Blender 3.2.2 and 3.3 Beta.
Member

Added subscriber: @PratikPB2123

Added subscriber: @PratikPB2123
Member

I think I'm able to replicate this when alpha value for glass material is close to 0
There might be a open report already since issue is replicable in 2.93 also (Or this maybe started to happen in newer driver versions?)
Simple .blend:
#100291.blend

GPU (optix) CPU
image.png image.png

Blender version: 3.4, 2.93
Operating system: Windows-10-10.0.22000-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3050 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 512.78``` 
I think I'm able to replicate this when alpha value for glass material is close to 0 There might be a open report already since issue is replicable in 2.93 also (Or this maybe started to happen in newer driver versions?) Simple .blend: [#100291.blend](https://archive.blender.org/developer/F13349573/T100291.blend) | GPU (optix) | CPU | | -- | -- | | ![image.png](https://archive.blender.org/developer/F13349579/image.png) | ![image.png](https://archive.blender.org/developer/F13349585/image.png) | - - - ```**System Information** Blender version: 3.4, 2.93 Operating system: Windows-10-10.0.22000-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3050 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 512.78```

Changed status from 'Needs Triage' to: 'Confirmed'

Changed status from 'Needs Triage' to: 'Confirmed'

Thanks for testing, marking as confirmed then.

Thanks for testing, marking as confirmed then.
Philipp Oeser removed the
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Reference: blender/blender#100291
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