Copy Rotation: implement new mixing modes that actually work.

Upon close inspection, the way the Offset mode works in the
Copy Rotation constraint makes no sense, and in fact, destroys
the rotation of its owner unless either it's single axis, or
the order is set specifically to `ZYX Euler`.

Since it can't simply be changed because of backward compatibility
concerns, replace the checkbox with a dropdown that provides a set
of new modes that actually make sense.

Specifically, add a mode that simply adds Euler components together,
and two options that use matrix multiplication in different order.

The Python use_offset property is replaced with compatibility stubs.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D5640

1 files changed, 15 insertions, 1 deletions

diff --git a/source/blender/blenlib/intern/math_matrix.c b/source/blender/blenlib/intern/math_matrix.c
index 7c1b44978e2..e9d196ccdbb 100644
--- a/source/blender/blenlib/intern/math_matrix.c
+++ b/source/blender/blenlib/intern/math_matrix.c
@@ -2164,7 +2164,7 @@ void rotate_m4(float mat[4][4], const char axis, const float angle)
 }
 
 /** Scale a matrix in-place. */
-void rescale_m4(float mat[4][4], float scale[3])
+void rescale_m4(float mat[4][4], const float scale[3])
 {
   mul_v3_fl(mat[0], scale[0]);
   mul_v3_fl(mat[1], scale[1]);
@@ -2359,6 +2359,20 @@ bool equals_m4m4(const float mat1[4][4], const float mat2[4][4])
 /**
  * Make a 4x4 matrix out of 3 transform components.
  * Matrices are made in the order: `scale * rot * loc`
+ */
+void loc_rot_size_to_mat4(float mat[4][4],
+                          const float loc[3],
+                          const float rot[3][3],
+                          const float size[3])
+{
+  copy_m4_m3(mat, rot);
+  rescale_m4(mat, size);
+  copy_v3_v3(mat[3], loc);
+}
+
+/**
+ * Make a 4x4 matrix out of 3 transform components.
+ * Matrices are made in the order: `scale * rot * loc`
  *
  * TODO: need to have a version that allows for rotation order...
  */