I'm trying to convert a model to a lower-poly version to use as a collision mesh. What's the best way to go about this? I've tried deleting edges, but this seems to only work when the adjoining triangles can combine to form a triangle, not a quad. Otherwise I just get a single triangle and a triangle-shaped gap. Is there a way to combine coplanar tris back into quads or n-gons? Google has been utterly useless so far.