[Bf-blender-cvs] [50f9681] master: Docs: comment on line-sphere intersection

[Campbell Barton]

Commit: 50f9681e151361fe6685582cb887818fa2092131
Author: Campbell Barton
Date:   Sun Apr 10 22:18:05 2016 +1000
Branches: master
https://developer.blender.org/rB50f9681e151361fe6685582cb887818fa2092131

Docs: comment on line-sphere intersection

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

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

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

diff --git a/source/blender/blenlib/intern/math_geom.c b/source/blender/blenlib/intern/math_geom.c
index e1de461..482709e 100644
--- a/source/blender/blenlib/intern/math_geom.c
+++ b/source/blender/blenlib/intern/math_geom.c
@@ -839,6 +839,14 @@ bool isect_seg_seg_v2_simple(const float v1[2], const float v2[2], const float v
  * \param l1, l2: Coordinates (point of line).
  * \param sp, r:  Coordinate and radius (sphere).
  * \return r_p1, r_p2: Intersection coordinates.
+ *
+ * \note The order of assignment for intersection points (\a r_p1, \a r_p2) is predictable,
+ * based on the direction defined by ``l2 - l1``,
+ * this direction compared with the normal of each point on the sphere:
+ * \a r_p1 always has a >= 0.0 dot product.
+ * \a r_p2 always has a <= 0.0 dot product.
+ * For example, when \a l1 is inside the sphere and \a l2 is outside,
+ * \a r_p1 will always be between \a l1 and \a l2.
  */
 int isect_line_sphere_v3(const float l1[3], const float l2[3],
                          const float sp[3], const float r,