- Remove 'rotate_m2', unlike 'rotate_m4' it created a new matrix
duplicating 'angle_to_mat2' - now used instead.
(better avoid matching functions having different behavior).
- Add 'axis_angle_to_mat4_single',
convenience wrapper for 'axis_angle_to_mat3_single'.
- Replace 'unit_m4(), rotate_m4()' with a single call to 'axis_angle_to_mat4_single'.
mat3_polar_decompose gives the right polar decomposition of given matrix,
as a pair (U, P) of matrices.
interp_m3_m3m3 uses that polar decomposition to perform a correct matrix interpolation,
even with non-uniformly scaled ones (where blend_m3_m3m3 would fail).
interp_m4_m4m4 just adds translation interpolation to the _m3 variant.
`BLI_space_transform_from_matrices()` defines a 'global-invariant' transform
(same point in global space, two different coordinates in local and target spaces).
New `BLI_space_transform_global_from_matrices()` is kind of opposite, it defines
a 'local-invariant' transform (two different points in global space, same coordinates in local and target spaces).
Useful to 'match' meshes.
That's really annoying that multiplication order is flipped
comparing mat3 and mat4 cases, but for the purposes of not
breaking all the branches which might use this stuff we'd
better keep order consistent with old version for now.
Suggestion here would be to make order consistent but rename
this functions to mult_* to make compilation fail instead
of failing and using wrong order silently.
It still warns the user that there may be an error, but the baking goes
on. Also using the new is_uniform_scaled_m4() instead of float comparison.
Reported and fix suggested by Campbell Barton as a concern over 2bfc3deb
Issue was caused by inverting a degenerate matrix when
evaluating drivers.
Solved by using tweaked inverse code (same as used in Cycles).
Should have no affect on cases when matrix is not degenerate.
