That would work great, except ellipsoids are ALWAYS used for entity vs. world interactions. The POLYGON flag only affects entity vs. entity interactions.
Yeah, I've already tried this (my actual model is just a cube, since it's an FPS), but all entity vs. level collisions are ellipsoid based. I don't think there's a way to get around that, so I need to find a way to prevent the playing getting stuck, or simply fix the problem quickly whenever it happens.
