BLI_math_rotation: properly name the quaternion power function.

"angular mult factor" is a completely unintelligible description
for a function that raises a unit quaternion to the scalar power.

2 files changed, 5 insertions, 3 deletions

diff --git a/source/blender/blenlib/BLI_math_rotation.h b/source/blender/blenlib/BLI_math_rotation.h
index 5b1568ab902..2bc82bac8d8 100644
--- a/source/blender/blenlib/BLI_math_rotation.h
+++ b/source/blender/blenlib/BLI_math_rotation.h
@@ -53,7 +53,8 @@ void copy_qt_qt(float q[4], const float a[4]);
 void mul_qt_qtqt(float q[4], const float a[4], const float b[4]);
 void mul_qt_v3(const float q[4], float r[3]);
 void mul_qt_fl(float q[4], const float f);
-void mul_fac_qt_fl(float q[4], const float f);
+
+void pow_qt_fl_normalized(float q[4], const float f);
 
 void sub_qt_qtqt(float q[4], const float a[4], const float b[4]);
 
diff --git a/source/blender/blenlib/intern/math_rotation.c b/source/blender/blenlib/intern/math_rotation.c
index 3e74173ef78..8e5b3f0000e 100644
--- a/source/blender/blenlib/intern/math_rotation.c
+++ b/source/blender/blenlib/intern/math_rotation.c
@@ -193,9 +193,10 @@ void sub_qt_qtqt(float q[4], const float q1[4], const float q2[4])
 	mul_qt_qtqt(q, q1, nq2);
 }
 
-/* angular mult factor */
-void mul_fac_qt_fl(float q[4], const float fac)
+/* raise a unit quaternion to the specified power */
+void pow_qt_fl_normalized(float q[4], const float fac)
 {
+	BLI_ASSERT_UNIT_QUAT(q);
 	const float angle = fac * saacos(q[0]); /* quat[0] = cos(0.5 * angle), but now the 0.5 and 2.0 rule out */
 	const float co = cosf(angle);
 	const float si = sinf(angle);