diff options
Diffstat (limited to 'source/blender/blenlib/intern/math_matrix.c')
| -rw-r--r-- | source/blender/blenlib/intern/math_matrix.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/source/blender/blenlib/intern/math_matrix.c b/source/blender/blenlib/intern/math_matrix.c index 9e398239bc7..92cfd09f191 100644 --- a/source/blender/blenlib/intern/math_matrix.c +++ b/source/blender/blenlib/intern/math_matrix.c @@ -2388,6 +2388,22 @@ void interp_m3_m3m3(float R[3][3], const float A[3][3], const float B[3][3], con mat3_polar_decompose(A, U_A, P_A); mat3_polar_decompose(B, U_B, P_B); + /* Quaternions cannot represent an axis flip. If such a singularity is detected, choose a + * different decomposition of the matrix that still satisfies A = U_A * P_A but which has a + * positive determinant and thus no axis flips. This resolves T77154. + * + * Note that a flip of two axes is just a rotation of 180 degrees around the third axis, and + * three flipped axes are just an 180 degree rotation + a single axis flip. It is thus sufficient + * to solve this problem for single axis flips. */ + if (determinant_m3_array(U_A) < 0) { + mul_m3_fl(U_A, -1.0f); + mul_m3_fl(P_A, -1.0f); + } + if (determinant_m3_array(U_B) < 0) { + mul_m3_fl(U_B, -1.0f); + mul_m3_fl(P_B, -1.0f); + } + mat3_to_quat(quat_A, U_A); mat3_to_quat(quat_B, U_B); interp_qt_qtqt(quat, quat_A, quat_B, t); |