Description

Dynamic instancing is likely causing an issue where meshes that need shadows are getting combined with meshes that do not need shadows causing missing shadows. Tests were done with CSMs.

Reproduction rate is not consistent. So far it can be as high as 100% on some machines versus no reproduction on others.

Also tested in //UE5/Release-5.5 CL: 37835253 and on //UE5/Main, CL: 37850162

Steps to Reproduce

This bug is dependent on viewport size, camera position, engine version and CLs. Reproduction steps will list CLs tested along with their associated locations:

1. Download the Licensee's test project from the UDN ticket and open. Use one of the following versions and CLs:
//UE5/Release-5.4, CL: 35906825
//UE5/Release-5.5, CL: 37835253
//UE5/Main, CL: 37850162
2. Enable Preview Platform PC D3D Mobile
3. Confirm that "r.Mobile.Shadow.CSMShaderCullingMethod" is 1 (value from the constructor)
4. Set the viewport size to 1512x1074, and the screen percentage to 100 (using the Editor GUI).
5. Execute the console command, determined by which Engine version you are using:
5.4: BugItGo -2901.071491 -1960.447899 8976.824399 -37.442048 382.035553 0.000000
5.5: BugItGo -3030.579757 -1934.513820 8976.824219 -44.042047 380.235553 0.000000
Main: BugItGo -2896.475872 -1979.455793 8847.211840 -49.442047 383.035540 -0.000002
6. If there are no shadows on either set of boxes, skip to step 8.
7. If there are shadows on the near set of boxes, adjust the following until the shadows suddenly disappear from the near set of cubes.

  • Viewport size / aspect ratio
  • Camera rotation and location

8. To confirm the bug, toggle the visibility on "NewFolder2" in the outliner. If the shadows on the near cubes appear, when "NewFolder2" is invisible, and disappear when "NewFolder2" is visible, you have the bug. Otherwise, return to step 7.

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Unresolved
ComponentUE - Platform - Mobile
Affects Versions5.55.4.4
CreatedNov 11, 2024
UpdatedNov 13, 2024
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