Description

There are two UDNs related to this issue.  It makes the Path Tracer unusable with MGPU, with atmosphere enabled.

I already have a one-line fix implemented and tested.  The atmosphere scan line artifacts are caused by the atmosphere lookup texture not being generated on all GPUs, so it just needs an RDG_GPU_MASK_SCOPE where that happens.

Steps to Reproduce

Steps reported on UDN:

  1. Make sure SLI is enabled in NVIDIA Control Panel
  2. Launch the project with -MaxGPUCount=2 as launch parameter
  3. Create a map with PathTracingEnableReferenceAtmosphere enabled somewhere in the post process settings.
  4. Switch to Path Tracing
  5. Set CVAR r.PathTracing.MultiGPU 1{}

Observe scan line artifacts across the entire frame (helps to take a screenshot and zoom in).

Have Comments or More Details?

There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-176829 in the post.

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Fixed
ComponentUE - Graphics Features - Path Tracer
Affects Versions5.15.2
Target Fix5.2
Fix Commit24357439
Main Commit24357635
Release Commit24357439
CreatedFeb 10, 2023
ResolvedFeb 23, 2023
UpdatedApr 29, 2023
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