Blender Git Loki

specialize mat4 multiply routines

mul_m4_m4m4(R, A, B) gives us R = AB in general. Existing code assumed the worst, that A and B both alias the output R. For safety it makes internal copies of A and B before calculating & writing R.

This is the least common case. Usually all 3 matrices differ. Often we see M = AM or M = MB, but never M = MM.

With this revision mul_m4_m4m4 is called in exactly the same way but copies inputs only when needed. If you know the inputs are independent of the output use the "uniq" variant to skip the saftety checks.