knife sort_by_frac_along was re-calculating the reference factor for every test, change to only calculate once and use line_point_factor_v3().

also add zero division check for line_point_factor_v3() since the 2d version already checked for this.

1 files changed, 7 insertions, 0 deletions

diff --git a/source/blender/blenlib/intern/math_geom.c b/source/blender/blenlib/intern/math_geom.c
index 56921797659..c8de9108fc3 100644
--- a/source/blender/blenlib/intern/math_geom.c
+++ b/source/blender/blenlib/intern/math_geom.c
@@ -1654,9 +1654,16 @@ float closest_to_line_v2(float cp[2], const float p[2], const float l1[2], const
 float line_point_factor_v3(const float p[3], const float l1[3], const float l2[3])
 {
 	float h[3], u[3];
+	float dot;
 	sub_v3_v3v3(u, l2, l1);
 	sub_v3_v3v3(h, p, l1);
+#if 0
 	return (dot_v3v3(u, h) / dot_v3v3(u, u));
+#else
+	/* better check for zero */
+	dot = dot_v3v3(u, u);
+	return (dot != 0.0f) ? (dot_v3v3(u, h) / dot) : 0.0f;
+#endif
 }
 
 float line_point_factor_v2(const float p[2], const float l1[2], const float l2[2])