GPU/CPU difference when rendering with 1spp #50988
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Reference: blender/blender#50988
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System Information
win7-x64/gtx670
Blender Version
Broken: latest master ( tested with buildbot
9d873fc
) / 2.78 / 2.77 / 2.76Worked: 2.69
GPU render produces black dots on a very simple scene when rendered with 1 spp
iftest.blend
cpu seems fine here.
Asked on irc for a repro @bliblubli had dots on a cpu but not gpu, @nirved-1 had no issues what so ever...
[edit: oops wrong john]
Changed status to: 'Open'
Added subscribers: @nirved-1, @JohnRoper, @LazyDodo
Added subscribers: @Sergey, @LukasStockner
This is most likely a precision issue in the triangle intersection code.
I can reproduce some background pixels along the diagonal on the GPU (GTX 780), more of them on the CPU with AVX2 enabled, and no background pixels on the CPU without AVX2. That also explains why only some people can reproduce the issue.
If anybody else wants to test AVX2, just set the debug value to 256 (using the --debug-value argument or Ctrl+Alt+D), go to the debug panel in the render settings and disable AVX2.
CCing @Sergey since he fixed similar bugs in the past iirc.
Added subscriber: @bliblubli
Changed status from 'Open' to: 'Resolved'
no longer happens in master, i assume the landing of D1574 fixed it.