Prevent auto-simplification of UCX collision

I am trying to make custom UCX collision for a mesh that is going to be used as a splinemesh. The collision mesh I am importing is subdivided to correctly to match the visual mesh, but when I import it it removes subdividing edges on a plane. This wouldn’t be a problem if this were purely a static mesh, but it prevents it from properly warping along a spline.


In engine collision:


In use:

In use collision:

Hello Ethan,

It looks like the collision mesh being generated is only set to generate one plane in between each point on the spline. I would recommend either subdividing the spline with more points, or setting the collision generation to generate more planes in between each point on the spline.

How can I set the collision generation to generate more planes between each point?

If you’re stretching the original collision mesh using the spline, the original collision mesh needs to have more subdivisions along the length. You’ll need to make that mesh in your modeling software. In the modeling hierarchy, you’ll need to name the collision mesh with the prefix “UCX_[UnrealAssetName]”. Reimport the purple grid mesh, and Make sure to deselect “Auto Generate Collision” when you do.

For a detailed tutorial, I’d rtecommend this clip: UE4 - Tutorial - Custom Collisions! (Request!) - YouTube

I’m actually doing that already! The first image is my UCX collision mesh in Maya

My problem is that the subdivisions in the UCX are being lost when importing from fbx

In the static mesh, is the Collision toolbar button set to “Complex Collision”?

It is not.

I am also having the EXACT same problem. I made the UCX meshes for my spline mesh to have the same subdivisions so I can have smooth collision along my spline mesh…but on import the collision meshes are reduced heavily

Have you found a solution for this? Having the same issue.

I’m not sure, but it looks like when importing complex UCX-meshes, the engine simplifies them by removing some vertexes. I think there is some limitation on the complexity of UCX-meshes, because they are, in fact, converted into elements of the Convex collision. Therefore, as a variant of one of the solutions, I recommend splitting UCX meshes into simpler primitives that have a maximum of 8 vertices (cubes, parallelepipeds, prisms or cylinders or cones). As a result, you should get sets of UCX-meshes like this: UCX_MainMeshName_00, UCX_MainMeshName_01, UCX_MainMeshName_02, etc.

Can’t edit my previous post:
I recommend splitting UCX meshes into simpler primitives (cubes, parallelepipeds, prisms or cylinders, or cones)