Fix T60935: More numerically stable distance to ray computation

The old function was numerically very unstable for 2 reasons:
computing the square and then subtracting the results.

In the example in T60935 all precision was lost and it returned the distance 0
for all points.

I also removed the `depth` parameter since it wasn't used and computing
it would have made the code more complicated.

Reviewers: brecht, campbellbarton

Differential Revision: https://developer.blender.org/D4308

1 files changed, 2 insertions, 2 deletions

diff --git a/source/blender/blenlib/BLI_math_geom.h b/source/blender/blenlib/BLI_math_geom.h
index a564e5481b9..54a4a38b15e 100644
--- a/source/blender/blenlib/BLI_math_geom.h
+++ b/source/blender/blenlib/BLI_math_geom.h
@@ -109,9 +109,9 @@ float dist_signed_squared_to_corner_v3v3v3(
         const float p[3],
         const float v1[3], const float v2[3], const float v3[3],
         const float axis_ref[3]);
-float dist_squared_to_ray_v3(
+float dist_squared_to_ray_v3_normalized(
         const float ray_origin[3], const float ray_direction[3],
-        const float co[3], float *r_depth);
+        const float co[3]);
 float dist_squared_ray_to_seg_v3(
         const float ray_origin[3], const float ray_direction[3],
         const float v0[3], const float v1[3],