[Bf-blender-cvs] [becc85c] master: Math Lib: 2d ray-segment intersection function

[Campbell Barton]

Commit: becc85c5d487b0df834bbeb6b21f3f122bdedd10
Author: Campbell Barton
Date:   Fri Dec 11 11:25:24 2015 +1100
Branches: master
https://developer.blender.org/rBbecc85c5d487b0df834bbeb6b21f3f122bdedd10

Math Lib: 2d ray-segment intersection function

===================================================================

M	source/blender/blenlib/BLI_math_geom.h
M	source/blender/blenlib/intern/math_geom.c

===================================================================

diff --git a/source/blender/blenlib/BLI_math_geom.h b/source/blender/blenlib/BLI_math_geom.h
index bf48338..b0421c3 100644
--- a/source/blender/blenlib/BLI_math_geom.h
+++ b/source/blender/blenlib/BLI_math_geom.h
@@ -244,6 +244,11 @@ bool isect_ray_tri_watertight_v3_simple(
         const float v0[3], const float v1[3], const float v2[3],
         float *r_lambda, float r_uv[2]);
 
+bool isect_ray_seg_v2(
+        const float p1[3], const float d[3],
+        const float v0[3], const float v1[3],
+        float *r_lambda, float *r_u);
+
 /* point in polygon */
 bool isect_point_poly_v2(const float pt[2], const float verts[][2], const unsigned int nr, const bool use_holes);
 bool isect_point_poly_v2_int(const int pt[2], const int verts[][2], const unsigned int nr, const bool use_holes);
diff --git a/source/blender/blenlib/intern/math_geom.c b/source/blender/blenlib/intern/math_geom.c
index 0ff12eb..5b809ab 100644
--- a/source/blender/blenlib/intern/math_geom.c
+++ b/source/blender/blenlib/intern/math_geom.c
@@ -1495,6 +1495,51 @@ bool isect_ray_tri_threshold_v3(
 }
 #endif
 
+
+bool isect_ray_seg_v2(
+        const float p1[3], const float d[3],
+        const float v0[3], const float v1[3],
+        float *r_lambda, float *r_u)
+{
+	float v0_local[2], v1_local[2];
+	sub_v2_v2v2(v0_local, v0, p1);
+	sub_v2_v2v2(v1_local, v1, p1);
+
+	float s10[2];
+	float det;
+
+	sub_v2_v2v2(s10, v1_local, v0_local);
+
+	det = cross_v2v2(d, s10);
+	if (det != 0.0f) {
+		const float v = cross_v2v2(v0_local, v1_local);
+		float p[2] = {(d[0] * v) / det, (d[1] * v) / det};
+
+		const float t = (dot_v2v2(p, d) / dot_v2v2(d, d));
+		if ((t >= 0.0f) == 0) {
+			return false;
+		}
+
+		float h[2];
+		sub_v2_v2v2(h, v1_local, p);
+		const float u = (dot_v2v2(s10, h) / dot_v2v2(s10, s10));
+		if ((u >= 0.0f && u <= 1.0f) == 0) {
+			return false;
+		}
+
+		if (r_lambda) {
+			*r_lambda = t;
+		}
+		if (r_u) {
+			*r_u = u;
+		}
+
+		return true;
+	}
+
+	return false;
+}
+
 /**
  * Check if a point is behind all planes.
  */