Skeletal mesh with per polygon collision only collides against section zero

While trying to enable per-polygon collisions for hitscan (LineTraceMultiByChannel in C++) of projectiles we hit what appears to be a bug. I’m able to get per-polygon collisions working with our characters. However, our characters use separate materials for their heads and some other body parts.

The collisions only work against the mesh section rendering with material slot 0. The other parts of the mesh are ignored by the collision check. I was able to reproduce this with other meshes with 4.18.2.

I’ve enabled bTraceComplex on the FCollisionQueryParams and have enabled the per-polygon options on the components in the editor. I’ve verified the settings are correct post spawn in the editor.

I cannot find any per-section settings in the mesh related to per-polygon collisions, so I will assume this is a bug.


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