Enabling physics on a skeletal mesh with per poly collision enabled crashes engine


I encounter this bug for years now and wonder why this never got fixed. I want to use per poly collision on my character, but also want to set some parts of the mesh to simulate physics. I have set up a physics asset to do so. As soon as I try to apply physical animation or set bodies to simulate physics my game crashes:

This is really annoying and I found no ‘good’ way to fix this. The only workaround I found so far is adding another SkeletalMesh component for simulating phyiscs and use the CopyPose Node on the anim graph.

I can use functions like “GetClosestPointOnPhysicsAsset” without any problem and it even returns the bone name as it should. So I guess that the physics asset is working in game and can be queried …

UE Version: Every version… currently I am testing on 4.26

Can confirm this is happening on my end too.

I wasn’t sure if this was a bug, or if simulating physics was incompatible with per poly collision on a skeletal mesh.

I don’t actually need physics collision on the mesh, I’m only using it for line traces, and using the physics asset’s simple colliders for collision.

It looks like the SkeletalMeshComponent->Bodies array is emptied when Per Poly Collision is enabled. Perhaps the engine assumes that you are going to use the polygons rather than the bodies, so empties it

Install debug symbols so your error message can be traced back.