I think you might be misunderstanding the meaning of ‘convex’. A convex mesh is one where
From a dictionary definition,
- (of a polygon) having only interior angles measuring less than 180°.
Basically, for a 3D mesh, there must be no two points on your mesh where you can draw a line between those points and the line leave the interior of your mesh. So even if the mesh is manifold and without holes, if there are dips or valleys in the surface then it’s not convex (a requirement of UCX_ collision)
It works in the editor when you check the box to use Complex Collision because then it will use every single mesh face as a collider. That’s why it’s both very accurate, and expensive. For your island, it would mean it’s calculating the collision based on 16k faces.
You have a couple of options that are more optimized than just clicking the box.
One, make a convex hull that can be your UCX_ mesh. This isn’t going to give you what you want, because it will remove all the valleys on the island, and be inaccurate.
Another option that would be more optimized than checking the ‘Use complex as simple’ box, would be to cut out only the faces that you will let the player walk on, and export that seperately, place it where your island is, and check ‘Use complex’ on that mesh. So you’re only calculating collision on faces that you actually need to.
Like this:
