PostGIS  2.5.2dev-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 767 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().

768 {
769  POINT3DZ c;
770  double r;
771  /*if start==end, then use pt distance */
772  if ( ( A->x == B->x) && (A->y == B->y) && (A->z == B->z) )
773  {
774  return lw_dist3d_pt_pt(p,A,dl);
775  }
776 
777 
778  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) );
779 
780  /*This is for finding the 3Dmaxdistance.
781  the maxdistance have to be between two vertexes,
782  compared to mindistance which can be between
783  two vertexes vertex.*/
784  if (dl->mode == DIST_MAX)
785  {
786  if (r>=0.5)
787  {
788  return lw_dist3d_pt_pt(p,A,dl);
789  }
790  if (r<0.5)
791  {
792  return lw_dist3d_pt_pt(p,B,dl);
793  }
794  }
795 
796  if (r<0) /*If the first vertex A is closest to the point p*/
797  {
798  return lw_dist3d_pt_pt(p,A,dl);
799  }
800  if (r>1) /*If the second vertex B is closest to the point p*/
801  {
802  return lw_dist3d_pt_pt(p,B,dl);
803  }
804 
805  /*else if the point p is closer to some point between a and b
806  then we find that point and send it to lw_dist3d_pt_pt*/
807  c.x=A->x + r * (B->x-A->x);
808  c.y=A->y + r * (B->y-A->y);
809  c.z=A->z + r * (B->z-A->z);
810 
811  return lw_dist3d_pt_pt(p,&c,dl);
812 }
double z
Definition: liblwgeom.h:337
double y
Definition: liblwgeom.h:337
double x
Definition: liblwgeom.h:337
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:832
int mode
Definition: measures3d.h:44
#define DIST_MAX
Definition: measures.h:43
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