Description

The cause of the crash is out-of-range access to the array.
ExcludeDecals eliminates the mesh instance to which the decal material is assigned, but it seems that the MeshCommand has been registered.

The relevant part is in the GatherRayTracingWorldInstances function of DeferredShadingRenderer.cpp.
There is a part of this function that checks the ExcludeDecals flag, but I have confirmed that the crash can be avoided by moving this branch instruction before the previous command addition process.

.\Engine\Source\Runtime\Renderer\Private\DeferredShadingRenderer.cpp
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Steps to Reproduce
  1. Launch the editor with Enable Raytracing
  2. Place the cube on the level and assign the decal material
  3. Enter r.RayTracing.ExcludeDecals 1 to console command
  4. Crash when moving cube
    [Image Removed]

I have attached this settings project.
Setting r.RayTracing.ExcludeDecals 1 in this project will reproduce the crash.
Empty425.zip[Image Removed]

 
 

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Fixed
ComponentRendering - Ray Tracing
Affects Versions4.25
Target Fix4.26
Fix Commit14328853
Release Commit14328853
CreatedSep 16, 2020
ResolvedSep 16, 2020
UpdatedSep 17, 2020