Blender Git Loki

Fix T89330 Exact Boolean fails on a simple model.

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.