Complex collision mesh

i have a problem and a question
what does complex collision mesh in the collision properties do ??
i have a problem with using a mesh as another’s complex collision it’s a stair asset i have exported from megascans using auto convex wasn’t so well and the complex collision has way too any verts so i decided importing the mesh into blender and making a simpler mesh to be used as the collision i have tried creating a completely new mesh with collision setup as UCX_ but once imported it simplifies it i’m not even sure if it’s the right way but i don’t no of any others please help

here’s a video of my problem : complex collision mesh - YouTube

  1. Complex collision, when set, will calculate collision per vertex. It uses the same mesh model.

  2. Importing UCX colliders will simplify if unreal detects concave angles ( or convex, whichever is the one where it bends in ) like the shape of the stairs. It may sound a little odd but you can make multiple box primitives in your 3d software (or unreal) and export out all of them and it won’t simplify them. Essentially a box per step.

Check out the collision section of their docs:

Scroll down to the collision section and look at the green and red example for UCX collision. Also note the lollipop example where they use multiple collider meshes. If they tried a single mesh, the engine would simplify it to resemble a collider in the shape of a kite sort of. There is also a note about leaving a gap between colliders instead of having them overlap but I’ve seen overlap in other collision examples by epic.