Static mesh doesn't have complex collision, no matter what I do. WTF?

I’m doing a line trace with bTraceComplex=true (it’s for a bullet) so I want to hit complex collision, i.e. the visual mesh. I’ve got a static mesh with collision set to BlockAll and the trace channel I’m using is also set to Block in that collision profile. The trace goes right through the mesh with no collision result. When I turn on the complex collision display in the static mesh editor, nothing is shown. I don’t see any option to generate complex collision; only options for generating simple collision, which I do not want. The Collision Complexity setting in the static mesh editor is Project Default, but it doesn’t matter what I set it to; nothing works.

The only way I can get a collision on this mesh is to generate simple collision then set Collision Complexity to Use Simple As Complex. This gets a collision result but it looks wrong because… it’s simple collision.

I need to collide against the visual mesh, not some simple collision hull. For other meshes, this works just fine and doesn’t require any special setting. I don’t understand what the deal is here…? Why would a particular mesh just not have complex collision, at all? What gives?

Turns out there’s an Enable Collision checkbox up in the LOD sections, per-material, which was disabled on this asset because… reasons. Checking the box makes complex collision be A Thing again.


Hi, greetings from 2022, your forum post really helped me out. Thanks for posting your solution! You’re the real MVP.

for me the solution was to change the ‘complex collision mesh’ to the same static mesh

Please could you explain more clear, I am having the same issue with many blueprint in the scene but I don’t find what you mentioned ?

Looks like it’s here, under Details > LOD 0 > Sections. Each material has an Enable Collision checkbox which I also just found was unticked on a bunch of assets. Enabling this allowed dragging objects from Place Actors to snap to geometry again, which had not been working for some objects.

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