I am experimenting with a relatively large static cube mesh, with no collision mesh and collision complexity set to “Use Complex Collision As Simple”. Two smaller spherical meshes, with spherical collision meshes configured, simulate physics on, gravity on, movable set, are initially located just above the cube mesh. It looks like this in the editor:
When I press “play” on the level, the results are inconsistent.
The smaller sphere falls entirely through, while the larger one disappears inside the cube:
Or both spheres disappear inside the cube:
Or the larger sphere falls through and the small one disappears:
If I scale up the spheres, the problem seems to resolve. If I use a box collision mesh with the sphere, the problem disappears.
This example is a simple presentation of what I think is happening on the level I am currently prototyping: a planet-scale spherical mesh with a spacecraft that can land on its surface. The complex collision as simple option on the spherical planet mesh appears to have this issue: the spacecraft will not collide with the mesh surface. I can use a spherical mesh, of course, but that generally results in collisions that are above or below the surface of the planet. I have tried many things at this point. Nanite on and off. Setting customized collision with the original mesh as the complex collision mesh. Nothing seems to work.
I confess I have only been working with UE 5.3 for a week or so, and am still figuring things out, but this one has me stumped…