Fix T89291: Objects with rotation deltas don't rotate in correct axes

Quaternion correction was not implemented and Euler values were being
incorrectly combined.

2 files changed, 28 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_math_rotation.h b/source/blender/blenlib/BLI_math_rotation.h
index fe995b2e46e..ef10d02f10f 100644
--- a/source/blender/blenlib/BLI_math_rotation.h
+++ b/source/blender/blenlib/BLI_math_rotation.h
@@ -164,6 +164,9 @@ void compatible_eul(float eul[3], const float old[3]);
 
 void rotate_eul(float eul[3], const char axis, const float angle);
 
+void add_eul_euleul(float r_eul[3], float a[3], float b[3], const short order);
+void sub_eul_euleul(float r_eul[3], float a[3], float b[3], const short order);
+
 /************************** Arbitrary Order Eulers ***************************/
 
 /* warning: must match the eRotationModes in DNA_action_types.h
diff --git a/source/blender/blenlib/intern/math_rotation.c b/source/blender/blenlib/intern/math_rotation.c
index 57fe99ce019..469cd573372 100644
--- a/source/blender/blenlib/intern/math_rotation.c
+++ b/source/blender/blenlib/intern/math_rotation.c
@@ -1924,6 +1924,31 @@ void eulO_to_gimbal_axis(float gmat[3][3], const float eul[3], const short order
   gmat[R->axis[2]][R->axis[2]] = 1;
 }
 
+void add_eul_euleul(float r_eul[3], float a[3], float b[3], const short order)
+{
+  float quat[4], quat_b[4];
+
+  eulO_to_quat(quat, a, order);
+  eulO_to_quat(quat_b, b, order);
+
+  mul_qt_qtqt(quat, quat_b, quat);
+
+  quat_to_eulO(r_eul, order, quat);
+}
+
+void sub_eul_euleul(float r_eul[3], float a[3], float b[3], const short order)
+{
+  float quat[4], quat_b[4];
+
+  eulO_to_quat(quat, a, order);
+  eulO_to_quat(quat_b, b, order);
+
+  invert_qt_normalized(quat_b);
+  mul_qt_qtqt(quat, quat_b, quat);
+
+  quat_to_eulO(r_eul, order, quat);
+}
+
 /******************************* Dual Quaternions ****************************/
 
 /**