PostGIS  2.3.8dev-r@@SVN_REVISION@@

◆ ptarray_contains_point_partial()

int ptarray_contains_point_partial ( const POINTARRAY pa,
const POINT2D pt,
int  check_closed,
int *  winding_number 
)

Definition at line 746 of file ptarray.c.

References FP_MAX, FP_MIN, getPoint2d_cp(), LW_BOUNDARY, LW_INSIDE, LW_OUTSIDE, lw_pt_in_seg(), lw_segment_side(), lwerror(), POINTARRAY::npoints, p2d_same(), POINT2D::x, and POINT2D::y.

Referenced by lwcompound_contains_point(), and ptarray_contains_point().

747 {
748  int wn = 0;
749  int i;
750  double side;
751  const POINT2D *seg1;
752  const POINT2D *seg2;
753  double ymin, ymax;
754 
755  seg1 = getPoint2d_cp(pa, 0);
756  seg2 = getPoint2d_cp(pa, pa->npoints-1);
757  if ( check_closed && ! p2d_same(seg1, seg2) )
758  lwerror("ptarray_contains_point called on unclosed ring");
759 
760  for ( i=1; i < pa->npoints; i++ )
761  {
762  seg2 = getPoint2d_cp(pa, i);
763 
764  /* Zero length segments are ignored. */
765  if ( seg1->x == seg2->x && seg1->y == seg2->y )
766  {
767  seg1 = seg2;
768  continue;
769  }
770 
771  ymin = FP_MIN(seg1->y, seg2->y);
772  ymax = FP_MAX(seg1->y, seg2->y);
773 
774  /* Only test segments in our vertical range */
775  if ( pt->y > ymax || pt->y < ymin )
776  {
777  seg1 = seg2;
778  continue;
779  }
780 
781  side = lw_segment_side(seg1, seg2, pt);
782 
783  /*
784  * A point on the boundary of a ring is not contained.
785  * WAS: if (fabs(side) < 1e-12), see #852
786  */
787  if ( (side == 0) && lw_pt_in_seg(pt, seg1, seg2) )
788  {
789  return LW_BOUNDARY;
790  }
791 
792  /*
793  * If the point is to the left of the line, and it's rising,
794  * then the line is to the right of the point and
795  * circling counter-clockwise, so incremement.
796  */
797  if ( (side < 0) && (seg1->y <= pt->y) && (pt->y < seg2->y) )
798  {
799  wn++;
800  }
801 
802  /*
803  * If the point is to the right of the line, and it's falling,
804  * then the line is to the right of the point and circling
805  * clockwise, so decrement.
806  */
807  else if ( (side > 0) && (seg2->y <= pt->y) && (pt->y < seg1->y) )
808  {
809  wn--;
810  }
811 
812  seg1 = seg2;
813  }
814 
815  /* Sent out the winding number for calls that are building on this as a primitive */
816  if ( winding_number )
817  *winding_number = wn;
818 
819  /* Outside */
820  if (wn == 0)
821  {
822  return LW_OUTSIDE;
823  }
824 
825  /* Inside */
826  return LW_INSIDE;
827 }
int npoints
Definition: liblwgeom.h:370
#define FP_MIN(A, B)
double x
Definition: liblwgeom.h:327
int p2d_same(const POINT2D *p1, const POINT2D *p2)
Definition: lwalgorithm.c:49
const POINT2D * getPoint2d_cp(const POINTARRAY *pa, int n)
Returns a POINT2D pointer into the POINTARRAY serialized_ptlist, suitable for reading from...
Definition: lwgeom_api.c:485
#define LW_INSIDE
Constants for point-in-polygon return values.
double y
Definition: liblwgeom.h:327
#define LW_BOUNDARY
int lw_pt_in_seg(const POINT2D *P, const POINT2D *A1, const POINT2D *A2)
Returns true if P is between A1/A2.
Definition: lwalgorithm.c:95
#define LW_OUTSIDE
int lw_segment_side(const POINT2D *p1, const POINT2D *p2, const POINT2D *q)
lw_segment_side()
Definition: lwalgorithm.c:64
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:102
#define FP_MAX(A, B)
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