7223a0348f
The problem was an optimization I put in to triangulate quads. It was wrong if the quad, after projecting onto a 2d plane, was not convex. Handling quads the same as other faces fixes the bug. Unfortunately, this will slow down Exact Boolean when the input has many quads (the usual case, of course). Will attempt to fix that with a later change, but for now, this at least restores correctness.