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.
The existing hash function didn't work well with Set's method of
masking to the lower bits, because many verts have zeros in the
lower bits.
Also, replaced VectorSet with Set for Vert deduping.
The code for determining coplanar clusters had a bug where it would
miss some triangles. The fix for now is to just put triangles in
the cluster if their bounding boxes overlap. This works but maybe
makes clusters bigger then they have to be. I'll follow this commit
with work on making the CDT routine faster when using exact arithmetic.
Also removed a lot of unused code, and added some new intersect
performance tests.
The code to detect non-trivial coplanar intersection sometimes
falsely said there wasn't one. This caused some coplanar intersections
to be missed. Also added a test for this case.
This is for design task T67744, Boolean Redesign.
It adds a choice of solver to the Boolean modifier and the
Intersect (Boolean) and Intersect (Knife) tools.
The 'Fast' choice is the current Bmesh boolean.
The new 'Exact' choice is a more advanced algorithm that supports
overlapping geometry and uses more robust calculations, but is
slower than the Fast choice.
The default with this commit is set to 'Exact'. We can decide before
the 2.91 release whether or not this is the right choice, but this
choice now will get us more testing and feedback on the new code.
