New implementation for twist brushes.

It has much better rotation and avoids the compression effect that old
twist brushes have. Also twisting is now non periodic, meaning you can
twist beyond 180 degrees. The amount of twist is also calculated
relative to the angle formed after first translating the mouse away from
the brush center.

1 files changed, 27 insertions, 4 deletions

diff --git a/source/blender/blenlib/intern/math_rotation.c b/source/blender/blenlib/intern/math_rotation.c
index cf9280d418f..2d044a13841 100644
--- a/source/blender/blenlib/intern/math_rotation.c
+++ b/source/blender/blenlib/intern/math_rotation.c
@@ -749,10 +749,33 @@ void eulO_to_axis_angle(float axis[3], float *angle, const float eul[3], const s
 	quat_to_axis_angle(axis, angle, q);
 }
 
-/* axis angle to 3x3 matrix - safer version (normalization of axis performed)
- *
- * note: we may want a normalized and non normalized version of this function.
- */
+/* axis angle to 3x3 matrix - note: requires that axis is normalized */
+void axis_angle_to_mat3_no_norm(float mat[3][3], const float nor[3], const float angle)
+{
+	float nsi[3], co, si, ico;
+
+	/* now convert this to a 3x3 matrix */
+	co = cosf(angle);
+	si = sinf(angle);
+
+	ico = (1.0f - co);
+	nsi[0] = nor[0] * si;
+	nsi[1] = nor[1] * si;
+	nsi[2] = nor[2] * si;
+
+	mat[0][0] = ((nor[0] * nor[0]) * ico) + co;
+	mat[0][1] = ((nor[0] * nor[1]) * ico) + nsi[2];
+	mat[0][2] = ((nor[0] * nor[2]) * ico) - nsi[1];
+	mat[1][0] = ((nor[0] * nor[1]) * ico) - nsi[2];
+	mat[1][1] = ((nor[1] * nor[1]) * ico) + co;
+	mat[1][2] = ((nor[1] * nor[2]) * ico) + nsi[0];
+	mat[2][0] = ((nor[0] * nor[2]) * ico) + nsi[1];
+	mat[2][1] = ((nor[1] * nor[2]) * ico) - nsi[0];
+	mat[2][2] = ((nor[2] * nor[2]) * ico) + co;
+}
+
+
+/* axis angle to 3x3 matrix - safer version (normalization of axis performed) */
 void axis_angle_to_mat3(float mat[3][3], const float axis[3], const float angle)
 {
 	float nor[3], nsi[3], co, si, ico;