Thanks for Sergey for finding the bug & patching, This fix works a bit differently.
Theres no need to allocate the customdata in the first place - since its written into. So add a flag for vert/edge/face/loop creation functions so they can skip customdata creation.
add type checking for element buffers, there was nothing stopping python from passing any element type into an argument when in some cases only verts/edges/faces were expected.
now operator args define which types they support.
- update face normals when triangulating.
- avoid divide by zero when interpolating customdata on a zero length edge.
- replace zero float comparisons with fabsf() < FLT_EPSILON to avoid numeric error.
also renamed BLI_heap_empty() --> BLI_heap_is_empty() so its obviously readonly function.
- building without python works again
- rename maxi/mini to i_max/i_min (so thay are available for function names)
- some minor edits to IK stretch setting (no functional changes).
- use angle_normalized_v3v3() where both vectors are known to be normalized.
- remove needless radian to degrees conversions.
- move checks for customdata layers outside the inner loop (for bevel and crease).
On a user level, edge rotate now works better with multiple edges selected, it wont make zero area faces or rotate edges into existing ones.
With a single edge selected - rotate is less strict and will allow ugly resulting faces but still checks on duplicate edges.
API:
* BM_edge_rotate now takes a flag, to optionally...
** check for existing edge
** splice edge (rotate and merge)
** check for degenerate resulting faces (overlapping geometry, zero area)
** beauty - only rotate to a better fit.
... this allows it to still be used as a low level API function since all checks can be skipped.
* BM_edge_rotate() now works a bit different, it find the new edge rotation before joining the faces - exposed by BM_edge_rotate_calc().
* Added api call bmesh_radial_faceloop_find_vert() - Radial Find a Vertex Loop in Face
* improve check to see if edge rotate can be done,
was checking if both edges verts have an edge count of 2, which is really a meaningless test since the verts can have stray edges connected and the result wont work right.
instead check if the next verts in both faces share a vertex.
* add utility function BM_face_other_vert_loop() which gets the next loop in a face.
* add convenience function BM_edge_face_pair() which returns 2 faces for edges that have exactly 2 face users. (saves ugly e->l->radial_next ... in code) and is more readable.
