PostGIS  2.3.7dev-r@@SVN_REVISION@@
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 747 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().

748 {
749  POINT3DZ c;
750  double r;
751  /*if start==end, then use pt distance */
752  if ( ( A->x == B->x) && (A->y == B->y) && (A->z == B->z) )
753  {
754  return lw_dist3d_pt_pt(p,A,dl);
755  }
756 
757 
758  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) );
759 
760  /*This is for finding the 3Dmaxdistance.
761  the maxdistance have to be between two vertexes,
762  compared to mindistance which can be between
763  tvo vertexes vertex.*/
764  if (dl->mode == DIST_MAX)
765  {
766  if (r>=0.5)
767  {
768  return lw_dist3d_pt_pt(p,A,dl);
769  }
770  if (r<0.5)
771  {
772  return lw_dist3d_pt_pt(p,B,dl);
773  }
774  }
775 
776  if (r<0) /*If the first vertex A is closest to the point p*/
777  {
778  return lw_dist3d_pt_pt(p,A,dl);
779  }
780  if (r>1) /*If the second vertex B is closest to the point p*/
781  {
782  return lw_dist3d_pt_pt(p,B,dl);
783  }
784 
785  /*else if the point p is closer to some point between a and b
786  then we find that point and send it to lw_dist3d_pt_pt*/
787  c.x=A->x + r * (B->x-A->x);
788  c.y=A->y + r * (B->y-A->y);
789  c.z=A->z + r * (B->z-A->z);
790 
791  return lw_dist3d_pt_pt(p,&c,dl);
792 }
double z
Definition: liblwgeom.h:333
double y
Definition: liblwgeom.h:333
double x
Definition: liblwgeom.h:333
char * r
Definition: cu_in_wkt.c:24
int lw_dist3d_pt_pt(POINT3DZ *thep1, POINT3DZ *thep2, DISTPTS3D *dl)
Compares incomming points and stores the points closest to each other or most far away from each othe...
Definition: measures3d.c:812
int mode
Definition: measures3d.h:44
#define DIST_MAX
Definition: measures.h:40

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