[GRASS-dev] [GRASS GIS] #2734: v.distance: 3d point inside area is classified as outside

[GRASS GIS]

#2734: v.distance: 3d point inside area is classified as outside
-----------------------------+-------------------------
 Reporter:  annakrat         |      Owner:  grass-dev@…
     Type:  defect           |     Status:  new
 Priority:  normal           |  Milestone:  7.0.2
Component:  Vector           |    Version:  svn-trunk
 Keywords:  v.distance, box  |        CPU:  All
 Platform:  All              |
-----------------------------+-------------------------
 When a point is 3D and has different z coordinate than 0 and this point is
 inside 2D area, v.distance reports that this point is outside the area.
 The problem is in
 [https://trac.osgeo.org/grass/browser/grass/trunk/vector/v.distance/distance.c#L293
 distance.c], which calls
 [https://trac.osgeo.org/grass/browser/grass/trunk/lib/vector/Vlib/box.c#L31
 Vect_point_in_box] - the top and bottom of the  area's box are 0, the z
 coordinate (of the 3D point) is not.

 One solution is to do something like this:
 {{{
 Index: distance.c
 ===================================================================
 --- distance.c  (revision 66134)
 +++ distance.c  (working copy)
 @@ -291,7 +291,7 @@

      for (i = 0; i < Points->n_points; i++) {
         if (Vect_point_in_box(Points->x[i], Points->y[i],
 -                             Points->z[i], abox)) {
 +                             with_z ? Points->z[i] : 0, abox)) {

             int poly;
 }}}
 but then the comparison of doubles (0 == 0) in Vect_point_in_box might not
 always work.

 Or we could introduce a 2D version of the Vect_point_in_box function which
 checks x and y only.

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/2734>
GRASS GIS <https://grass.osgeo.org>