fix [#32646] Duplifaces can have wrong orientation with ngons

concave ngons could flip the dupliface, now use the faces normal when calculating the dupli-face.

1 files changed, 16 insertions, 1 deletions

diff --git a/source/blender/blenlib/intern/math_rotation.c b/source/blender/blenlib/intern/math_rotation.c
index e10b0b3298c..1392e88c168 100644
--- a/source/blender/blenlib/intern/math_rotation.c
+++ b/source/blender/blenlib/intern/math_rotation.c
@@ -613,13 +613,21 @@ void add_qt_qtqt(float result[4], const float quat1[4], const float quat2[4], co
 	result[3] = quat1[3] + t * quat2[3];
 }
 
-void tri_to_quat(float quat[4], const float v1[3], const float v2[3], const float v3[3])
+/* same as tri_to_quat() but takes pre-computed normal from the triangle
+ * used for ngons when we know their normal */
+void tri_to_quat_ex(float quat[4], const float v1[3], const float v2[3], const float v3[3],
+                    const float no_orig[3])
 {
 	/* imaginary x-axis, y-axis triangle is being rotated */
 	float vec[3], q1[4], q2[4], n[3], si, co, angle, mat[3][3], imat[3][3];
 
 	/* move z-axis to face-normal */
+#if 0
 	normal_tri_v3(vec, v1, v2, v3);
+#else
+	copy_v3_v3(vec, no_orig);
+	(void)v3;
+#endif
 
 	n[0] =  vec[1];
 	n[1] = -vec[0];
@@ -659,6 +667,13 @@ void tri_to_quat(float quat[4], const float v1[3], const float v2[3], const floa
 	mul_qt_qtqt(quat, q1, q2);
 }
 
+void tri_to_quat(float quat[4], const float v1[3], const float v2[3], const float v3[3])
+{
+	float vec[3];
+	normal_tri_v3(vec, v1, v2, v3);
+	tri_to_quat_ex(quat, v1, v2, v3, vec);
+}
+
 void print_qt(const char *str, const float q[4])
 {
 	printf("%s: %.3f %.3f %.3f %.3f\n", str, q[0], q[1], q[2], q[3]);