1 files changed, 29 insertions, 1 deletions
diff --git a/source/blender/blenlib/intern/math_geom.c b/source/blender/blenlib/intern/math_geom.c
index 4af56c66dde..afce5a602ed 100644
--- a/source/blender/blenlib/intern/math_geom.c
+++ b/source/blender/blenlib/intern/math_geom.c
@@ -486,7 +486,6 @@ int isect_line_tri_v3(const float p1[3], const float p2[3], const float v0[3], c
 	
 	return 1;
 }
-
 /* moved from effect.c
    test if the ray starting at p1 going in d direction intersects the triangle v0..v2
    return non zero if it does 
@@ -527,6 +526,35 @@ int isect_ray_tri_v3(const float p1[3], const float d[3], const float v0[3], con
 	return 1;
 }
 
+int isect_ray_plane_v3(float p1[3], float d[3], float v0[3], float v1[3], float v2[3], float *lambda, int clip)
+{
+	float p[3], s[3], e1[3], e2[3], q[3];
+	float a, f, u, v;
+	
+	sub_v3_v3v3(e1, v1, v0);
+	sub_v3_v3v3(e2, v2, v0);
+	
+	cross_v3_v3v3(p, d, e2);
+	a = dot_v3v3(e1, p);
+	/* note: these values were 0.000001 in 2.4x but for projection snapping on
+	 * a human head (1BU==1m), subsurf level 2, this gave many errors - campbell */
+	if ((a > -0.00000001f) && (a < 0.00000001f)) return 0;
+	f = 1.0f/a;
+	
+	sub_v3_v3v3(s, p1, v0);
+	
+	u = f * dot_v3v3(s, p);
+
+	cross_v3_v3v3(q, s, e1);
+	
+	v = f * dot_v3v3(d, q);
+
+	*lambda = f * dot_v3v3(e2, q);
+	if (clip && (*lambda < 0.0f)) return 0;
+
+	return 1;
+}
+
 int isect_ray_tri_epsilon_v3(const float p1[3], const float d[3], const float v0[3], const float v1[3], const float v2[3], float *lambda, float uv[2], const float epsilon)
 {
 	float p[3], s[3], e1[3], e2[3], q[3];