Clarity on Custom Collision Meshes. Potential UE5 Editor Bug.

I am trying to add custom collisions to a suitcase.

I want to use as the custom collision model a static mesh model I created in the UE5 Modelling tool.

I have created the static mesh in the modelling mode and assigned it to use complex collisions as simple because this is super low poly so even the complex collisions are only a few polygons.

Next in my suitcase mesh I have set it to use ‘Customised Collision’ and then set the ‘Complex Collision Mesh’ as the custom static mesh asset I made above. However, this still uses the suitcase mesh to create the complex collision mesh from rather than the custom mesh I assigned in ‘Complex Collision Mesh’.

I’m not sure what I’m doing wrong I have tried every variation of use simple as complex and complex as simple on both the custom mesh and the suitcase mesh. I just want to use the custom mesh I created as the collision mesh in my suitcase mesh.

This is behaving as intended. Collision geometry needs to be convex - your suitcase custom collision mesh has a large concave section in the middle.

You could add 5 (4 sides / one bottom piece) box collision meshes in the static mesh editor - or in your DCC.

Some useful info can be found in the collision section of this doc.

Also, don’t go wild adding collision shapes for tiny bolts / switches etc - these all have a cost ultimately, and will not affect physics interactions to a noticeable degree.

For the sake of performance, probably best not to get into the habit of using complex collision as simple - however, if this is a portfolio piece and you’re not worried about perf you’ll be fine.

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Thanks. I will use that instead. But is there a way to use the collisions of another static mesh? They show up in the static mesh editor they just don’t seem to be usable.