PostGIS  2.5.1dev-r@@SVN_REVISION@@

## ◆ lw_dist3d_pt_seg()

 int lw_dist3d_pt_seg ( POINT3DZ * p, POINT3DZ * A, POINT3DZ * B, DISTPTS3D * dl )

If searching for min distance, this one finds the closest point on segment A-B from p.

if searching for max distance it just sends p-A and p-B to pt-pt calculation

Definition at line 744 of file measures3d.c.

References DIST_MAX, lw_dist3d_pt_pt(), DISTPTS3D::mode, r, POINT3DZ::x, POINT3DZ::y, and POINT3DZ::z.

Referenced by lw_dist3d_pt_ptarray(), and lw_dist3d_seg_seg().

745 {
746  POINT3DZ c;
747  double r;
748  /*if start==end, then use pt distance */
749  if ( ( A->x == B->x) && (A->y == B->y) && (A->z == B->z) )
750  {
751  return lw_dist3d_pt_pt(p,A,dl);
752  }
753
754
755  r = ( (p->x-A->x) * (B->x-A->x) + (p->y-A->y) * (B->y-A->y) + ( p->z-A->z) * (B->z-A->z) )/( (B->x-A->x)*(B->x-A->x) +(B->y-A->y)*(B->y-A->y)+(B->z-A->z)*(B->z-A->z) );
756
757  /*This is for finding the 3Dmaxdistance.
758  the maxdistance have to be between two vertexes,
759  compared to mindistance which can be between
760  two vertexes vertex.*/
761  if (dl->mode == DIST_MAX)
762  {
763  if (r>=0.5)
764  {
765  return lw_dist3d_pt_pt(p,A,dl);
766  }
767  if (r<0.5)
768  {
769  return lw_dist3d_pt_pt(p,B,dl);
770  }
771  }
772
773  if (r<0) /*If the first vertex A is closest to the point p*/
774  {
775  return lw_dist3d_pt_pt(p,A,dl);
776  }
777  if (r>1) /*If the second vertex B is closest to the point p*/
778  {
779  return lw_dist3d_pt_pt(p,B,dl);
780  }
781
782  /*else if the point p is closer to some point between a and b
783  then we find that point and send it to lw_dist3d_pt_pt*/
784  c.x=A->x + r * (B->x-A->x);
785  c.y=A->y + r * (B->y-A->y);
786  c.z=A->z + r * (B->z-A->z);
787
788  return lw_dist3d_pt_pt(p,&c,dl);
789 }
double z
Definition: liblwgeom.h:336
double y
Definition: liblwgeom.h:336
double x
Definition: liblwgeom.h:336
char * r
Definition: cu_in_wkt.c:24
int lw_dist3d_pt_pt(POINT3DZ *thep1, POINT3DZ *thep2, DISTPTS3D *dl)
Compares incoming points and stores the points closest to each other or most far away from each other...
Definition: measures3d.c:809
int mode
Definition: measures3d.h:44
#define DIST_MAX
Definition: measures.h:40
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