BLI_math: add mat3_polar_decompose, interp_m3_m3m3 and interp_m4_m4m4.

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.

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_math_matrix.h b/source/blender/blenlib/BLI_math_matrix.h
index d7a309e0835..80a399ac6d7 100644
--- a/source/blender/blenlib/BLI_math_matrix.h
+++ b/source/blender/blenlib/BLI_math_matrix.h
@@ -215,6 +215,8 @@ void mat4_to_loc_rot_size(float loc[3], float rot[3][3], float size[3], float wm
 void mat4_to_loc_quat(float loc[3], float quat[4], float wmat[4][4]);
 void mat4_decompose(float loc[3], float quat[4], float size[3], float wmat[4][4]);
 
+void mat3_polar_decompose(float mat3[3][3], float r_U[3][3], float r_P[3][3]);
+
 void loc_eul_size_to_mat4(float R[4][4],
                           const float loc[3], const float eul[3], const float size[3]);
 void loc_eulO_size_to_mat4(float R[4][4],
@@ -227,6 +229,9 @@ void loc_axisangle_size_to_mat4(float R[4][4],
 void blend_m3_m3m3(float R[3][3], float A[3][3], float B[3][3], const float t);
 void blend_m4_m4m4(float R[4][4], float A[4][4], float B[4][4], const float t);
 
+void interp_m3_m3m3(float R[3][3], float A[3][3], float B[3][3], const float t);
+void interp_m4_m4m4(float R[4][4], float A[4][4], float B[4][4], const float t);
+
 bool is_negative_m3(float mat[3][3]);
 bool is_negative_m4(float mat[4][4]);