add angle_to_mat2 utility function.

3 files changed, 18 insertions, 10 deletions

diff --git a/source/blender/blenlib/BLI_math_rotation.h b/source/blender/blenlib/BLI_math_rotation.h
index 87c065f3016..42161279bfd 100644
--- a/source/blender/blenlib/BLI_math_rotation.h
+++ b/source/blender/blenlib/BLI_math_rotation.h
@@ -104,7 +104,8 @@ void quat_to_axis_angle(float axis[3], float *angle, const float q[4]);
 void mat3_to_axis_angle(float axis[3], float *angle, float M[3][3]);
 void mat4_to_axis_angle(float axis[3], float *angle, float M[4][4]);
 
-void single_axis_angle_to_mat3(float R[3][3], const char axis, const float angle);
+void axis_angle_to_mat3_single(float R[3][3], const char axis, const float angle);
+void      angle_to_mat2(float R[2][2], const float angle);
 
 /******************************** XYZ Eulers *********************************/
 
diff --git a/source/blender/blenlib/intern/math_rotation.c b/source/blender/blenlib/intern/math_rotation.c
index c9919e7be37..6bac102e1b1 100644
--- a/source/blender/blenlib/intern/math_rotation.c
+++ b/source/blender/blenlib/intern/math_rotation.c
@@ -817,7 +817,8 @@ void mat4_to_axis_angle(float axis[3], float *angle, float mat[4][4])
 	quat_to_axis_angle(axis, angle, q);
 }
 
-void single_axis_angle_to_mat3(float mat[3][3], const char axis, const float angle)
+/* rotation matrix from a single axis */
+void axis_angle_to_mat3_single(float mat[3][3], const char axis, const float angle)
 {
 	const float angle_cos = cosf(angle);
 	const float angle_sin = sinf(angle);
@@ -862,6 +863,18 @@ void single_axis_angle_to_mat3(float mat[3][3], const char axis, const float ang
 	}
 }
 
+void angle_to_mat2(float mat[2][2], const float angle)
+{
+	const float angle_cos = cosf(angle);
+	const float angle_sin = sinf(angle);
+
+	/* 2D rotation matrix */
+	mat[0][0] =  angle_cos;
+	mat[0][1] =  angle_sin;
+	mat[1][0] = -angle_sin;
+	mat[1][1] =  angle_cos;
+}
+
 /******************************** XYZ Eulers *********************************/
 
 /* XYZ order */
diff --git a/source/blender/python/mathutils/mathutils_Matrix.c b/source/blender/python/mathutils/mathutils_Matrix.c
index d471cd05a2b..3e5dcc28903 100644
--- a/source/blender/python/mathutils/mathutils_Matrix.c
+++ b/source/blender/python/mathutils/mathutils_Matrix.c
@@ -522,18 +522,12 @@ static PyObject *C_Matrix_Rotation(PyObject *cls, PyObject *args)
 		axis_angle_to_mat3((float (*)[3])mat, tvec, angle);
 	}
 	else if (matSize == 2) {
-		const float angle_cos = cosf(angle);
-		const float angle_sin = sinf(angle);
+		angle_to_mat2((float (*)[2])mat, angle);
 
-		/* 2D rotation matrix */
-		mat[0] =  angle_cos;
-		mat[1] =  angle_sin;
-		mat[2] = -angle_sin;
-		mat[3] =  angle_cos;
 	}
 	else {
 		/* valid axis checked above */
-		single_axis_angle_to_mat3((float (*)[3])mat, axis[0], angle);
+		axis_angle_to_mat3_single((float (*)[3])mat, axis[0], angle);
 	}
 
 	if (matSize == 4) {