Math Lib: add isect_line_line_epsilon_v3

2 files changed, 21 insertions, 5 deletions

diff --git a/source/blender/blenlib/BLI_math_geom.h b/source/blender/blenlib/BLI_math_geom.h
index d3158ef7926..81ca2908619 100644
--- a/source/blender/blenlib/BLI_math_geom.h
+++ b/source/blender/blenlib/BLI_math_geom.h
@@ -130,9 +130,14 @@ int isect_line_sphere_v2(const float l1[2], const float l2[2], const float sp[2]
 int isect_seg_seg_v2_point(const float v1[2], const float v2[2], const float v3[2], const float v4[2], float vi[2]);
 bool isect_seg_seg_v2(const float v1[2], const float v2[2], const float v3[2], const float v4[2]);
 
-int isect_line_line_v3(const float v1[3], const float v2[3],
-                       const float v3[3], const float v4[3],
-                       float i1[3], float i2[3]);
+int isect_line_line_epsilon_v3(
+        const float v1[3], const float v2[3],
+        const float v3[3], const float v4[3], float i1[3], float i2[3],
+        const float epsilon);
+int isect_line_line_v3(
+        const float v1[3], const float v2[3],
+        const float v3[3], const float v4[3],
+        float i1[3], float i2[3]);
 bool isect_line_line_strict_v3(const float v1[3], const float v2[3],
                                const float v3[3], const float v4[3],
                                float vi[3], float *r_lambda);
diff --git a/source/blender/blenlib/intern/math_geom.c b/source/blender/blenlib/intern/math_geom.c
index 6ca98e52909..96a531bc4ea 100644
--- a/source/blender/blenlib/intern/math_geom.c
+++ b/source/blender/blenlib/intern/math_geom.c
@@ -1562,7 +1562,10 @@ bool isect_axial_line_tri_v3(const int axis, const float p1[3], const float p2[3
  * 1 - lines are coplanar, i1 is set to intersection
  * 2 - i1 and i2 are the nearest points on line 1 (v1, v2) and line 2 (v3, v4) respectively
  */
-int isect_line_line_v3(const float v1[3], const float v2[3], const float v3[3], const float v4[3], float i1[3], float i2[3])
+int isect_line_line_epsilon_v3(
+        const float v1[3], const float v2[3],
+        const float v3[3], const float v4[3], float i1[3], float i2[3],
+        const float epsilon)
 {
 	float a[3], b[3], c[3], ab[3], cb[3], dir1[3], dir2[3];
 	float d, div;
@@ -1588,7 +1591,7 @@ int isect_line_line_v3(const float v1[3], const float v2[3], const float v3[3],
 		return 0;
 	}
 	/* test if the two lines are coplanar */
-	else if (d > -0.000001f && d < 0.000001f) {
+	else if (UNLIKELY(fabsf(d) <= epsilon)) {
 		cross_v3_v3v3(cb, c, b);
 
 		mul_v3_fl(a, dot_v3v3(cb, ab) / div);
@@ -1628,6 +1631,14 @@ int isect_line_line_v3(const float v1[3], const float v2[3], const float v3[3],
 	}
 }
 
+int isect_line_line_v3(
+        const float v1[3], const float v2[3],
+        const float v3[3], const float v4[3], float i1[3], float i2[3])
+{
+	const float epsilon = 0.000001f;
+	return isect_line_line_epsilon_v3(v1, v2, v3, v4, i1, i2, epsilon);
+}
+
 /** Intersection point strictly between the two lines
  * \return false when no intersection is found
  */