Math Lib: ray_point_factor_v3 functions

Gives a bit better precision than creating a line in some cases,
use for ED_view3d_win_to_3d.

3 files changed, 40 insertions, 13 deletions

diff --git a/source/blender/blenlib/BLI_math_geom.h b/source/blender/blenlib/BLI_math_geom.h
index 7836f12a03e..45edaca544d 100644
--- a/source/blender/blenlib/BLI_math_geom.h
+++ b/source/blender/blenlib/BLI_math_geom.h
@@ -127,6 +127,12 @@ void closest_to_plane3_v3(float r_close[3], const float plane[3], const float pt
 /* Set 'r' to the point in triangle (t1, t2, t3) closest to point 'p' */
 void closest_on_tri_to_point_v3(float r[3], const float p[3], const float t1[3], const float t2[3], const float t3[3]);
 
+float ray_point_factor_v3_ex(
+        const float p[3], const float ray_origin[3], const float ray_direction[3],
+        const float epsilon, const float fallback);
+float ray_point_factor_v3(
+        const float p[3], const float ray_origin[3], const float ray_direction[3]);
+
 float line_point_factor_v3_ex(
         const float p[3], const float l1[3], const float l2[3],
         const float epsilon, const float fallback);
diff --git a/source/blender/blenlib/intern/math_geom.c b/source/blender/blenlib/intern/math_geom.c
index 482709e572f..49b52690a5b 100644
--- a/source/blender/blenlib/intern/math_geom.c
+++ b/source/blender/blenlib/intern/math_geom.c
@@ -2506,6 +2506,22 @@ float closest_to_line_v2(float r_close[2], const float p[2], const float l1[2],
 	return lambda;
 }
 
+float ray_point_factor_v3_ex(
+        const float p[3], const float ray_origin[3], const float ray_direction[3],
+        const float epsilon, const float fallback)
+{
+	float p_relative[3];
+	sub_v3_v3v3(p_relative, p, ray_origin);
+	const float dot = dot_v3v3(ray_direction, ray_direction);
+	return (fabsf(dot) > epsilon) ? (dot_v3v3(ray_direction, p_relative) / dot) : fallback;
+}
+
+float ray_point_factor_v3(
+        const float p[3], const float ray_origin[3], const float ray_direction[3])
+{
+	return ray_point_factor_v3_ex(p, ray_origin, ray_direction, 0.0f, 0.0f);
+}
+
 /**
  * A simplified version of #closest_to_line_v3
  * we only need to return the ``lambda``
diff --git a/source/blender/editors/space_view3d/view3d_project.c b/source/blender/editors/space_view3d/view3d_project.c
index c364148c9f1..cbabc8e56de 100644
--- a/source/blender/editors/space_view3d/view3d_project.c
+++ b/source/blender/editors/space_view3d/view3d_project.c
@@ -481,19 +481,22 @@ void ED_view3d_win_to_3d(const ARegion *ar, const float depth_pt[3], const float
 {
 	RegionView3D *rv3d = ar->regiondata;
 
-	float line_sta[3];
-	float line_end[3];
+	float ray_origin[3];
+	float ray_direction[3];
+	float lambda;
 
 	if (rv3d->is_persp) {
-		float mousevec[3], lambda;
-		copy_v3_v3(line_sta, rv3d->viewinv[3]);
-		ED_view3d_win_to_vector(ar, mval, mousevec);
-		add_v3_v3v3(line_end, line_sta, mousevec);
+		float plane[4];
+
+		copy_v3_v3(ray_origin, rv3d->viewinv[3]);
+		ED_view3d_win_to_vector(ar, mval, ray_direction);
 
 		/* note, we could use isect_line_plane_v3() however we want the intersection to be infront of the
 		 * view no matter what, so apply the unsigned factor instead */
-		lambda = line_plane_factor_v3(depth_pt, rv3d->viewinv[2], line_sta, line_end);
-		interp_v3_v3v3(out, line_sta, line_end, fabsf(lambda));
+		plane_from_point_normal_v3(plane, depth_pt, rv3d->viewinv[2]);
+
+		isect_ray_plane_v3(ray_origin, ray_direction, plane, &lambda, false);
+		lambda = fabsf(lambda);
 	}
 	else {
 		float dx = (2.0f * mval[0] / (float)ar->winx) - 1.0f;
@@ -504,13 +507,15 @@ void ED_view3d_win_to_3d(const ARegion *ar, const float depth_pt[3], const float
 			dx += rv3d->camdx * zoomfac;
 			dy += rv3d->camdy * zoomfac;
 		}
-		line_sta[0] = (rv3d->persinv[0][0] * dx) + (rv3d->persinv[1][0] * dy) + rv3d->viewinv[3][0];
-		line_sta[1] = (rv3d->persinv[0][1] * dx) + (rv3d->persinv[1][1] * dy) + rv3d->viewinv[3][1];
-		line_sta[2] = (rv3d->persinv[0][2] * dx) + (rv3d->persinv[1][2] * dy) + rv3d->viewinv[3][2];
+		ray_origin[0] = (rv3d->persinv[0][0] * dx) + (rv3d->persinv[1][0] * dy) + rv3d->viewinv[3][0];
+		ray_origin[1] = (rv3d->persinv[0][1] * dx) + (rv3d->persinv[1][1] * dy) + rv3d->viewinv[3][1];
+		ray_origin[2] = (rv3d->persinv[0][2] * dx) + (rv3d->persinv[1][2] * dy) + rv3d->viewinv[3][2];
 
-		add_v3_v3v3(line_end, line_sta, rv3d->viewinv[2]);
-		closest_to_line_v3(out, depth_pt, line_sta, line_end);
+		copy_v3_v3(ray_direction, rv3d->viewinv[2]);
+		lambda = ray_point_factor_v3(depth_pt, ray_origin, ray_direction);
 	}
+
+	madd_v3_v3v3fl(out, ray_origin, ray_direction, lambda);
 }
 
 void ED_view3d_win_to_3d_int(const ARegion *ar, const float depth_pt[3], const int mval[2], float out[3])