PostGIS  3.4.0dev-r@@SVN_REVISION@@

◆ lw_dist2d_point_poly()

int lw_dist2d_point_poly ( LWPOINT point,
LWPOLY poly,
DISTPTS dl 
)
  1. see if pt in outer boundary. if no, then treat the outer ring like a line
  2. if in the boundary, test to see if its in a hole. if so, then return dist to hole, else return 0 (point in polygon)

Definition at line 642 of file measures.c.

643 {
644  const POINT2D *p = getPoint2d_cp(point->point, 0);
645 
646  /* Max distance? Check only outer ring.*/
647  if (dl->mode == DIST_MAX)
648  return lw_dist2d_pt_ptarray(p, poly->rings[0], dl);
649 
650  /* Return distance to outer ring if not inside it */
651  if (ptarray_contains_point(poly->rings[0], p) == LW_OUTSIDE)
652  return lw_dist2d_pt_ptarray(p, poly->rings[0], dl);
653 
654  /*
655  * Inside the outer ring.
656  * Scan though each of the inner rings looking to
657  * see if its inside. If not, distance==0.
658  * Otherwise, distance = pt to ring distance
659  */
660  for (uint32_t i = 1; i < poly->nrings; i++)
661  if (ptarray_contains_point(poly->rings[i], p) != LW_OUTSIDE)
662  return lw_dist2d_pt_ptarray(p, poly->rings[i], dl);
663 
664  /* Is inside the polygon */
665  dl->distance = 0.0;
666  dl->p1.x = dl->p2.x = p->x;
667  dl->p1.y = dl->p2.y = p->y;
668  return LW_TRUE;
669 }
#define LW_TRUE
Return types for functions with status returns.
Definition: liblwgeom.h:93
int ptarray_contains_point(const POINTARRAY *pa, const POINT2D *pt)
Return 1 if the point is inside the POINTARRAY, -1 if it is outside, and 0 if it is on the boundary.
Definition: ptarray.c:753
#define LW_OUTSIDE
static const POINT2D * getPoint2d_cp(const POINTARRAY *pa, uint32_t n)
Returns a POINT2D pointer into the POINTARRAY serialized_ptlist, suitable for reading from.
Definition: lwinline.h:101
int lw_dist2d_pt_ptarray(const POINT2D *p, POINTARRAY *pa, DISTPTS *dl)
search all the segments of pointarray to see which one is closest to p1 Returns minimum distance betw...
Definition: measures.c:1130
#define DIST_MAX
Definition: measures.h:43
POINT2D p1
Definition: measures.h:52
POINT2D p2
Definition: measures.h:53
int mode
Definition: measures.h:54
double distance
Definition: measures.h:51
POINTARRAY * point
Definition: liblwgeom.h:471
POINTARRAY ** rings
Definition: liblwgeom.h:519
uint32_t nrings
Definition: liblwgeom.h:524
double y
Definition: liblwgeom.h:390
double x
Definition: liblwgeom.h:390

References DIST_MAX, DISTPTS::distance, getPoint2d_cp(), lw_dist2d_pt_ptarray(), LW_OUTSIDE, LW_TRUE, DISTPTS::mode, LWPOLY::nrings, DISTPTS::p1, DISTPTS::p2, LWPOINT::point, ptarray_contains_point(), LWPOLY::rings, POINT2D::x, and POINT2D::y.

Referenced by lw_dist2d_distribute_bruteforce().

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