PostGIS  2.5.0beta1dev-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 733 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 _lwt_AddPoint(), _lwt_CheckEdgeCrossing(), lwcompound_contains_point(), lwt_ChangeEdgeGeom(), and ptarray_contains_point().

734 {
735  int wn = 0;
736  uint32_t i;
737  double side;
738  const POINT2D *seg1;
739  const POINT2D *seg2;
740  double ymin, ymax;
741 
742  seg1 = getPoint2d_cp(pa, 0);
743  seg2 = getPoint2d_cp(pa, pa->npoints-1);
744  if ( check_closed && ! p2d_same(seg1, seg2) )
745  lwerror("ptarray_contains_point called on unclosed ring");
746 
747  for ( i=1; i < pa->npoints; i++ )
748  {
749  seg2 = getPoint2d_cp(pa, i);
750 
751  /* Zero length segments are ignored. */
752  if ( seg1->x == seg2->x && seg1->y == seg2->y )
753  {
754  seg1 = seg2;
755  continue;
756  }
757 
758  ymin = FP_MIN(seg1->y, seg2->y);
759  ymax = FP_MAX(seg1->y, seg2->y);
760 
761  /* Only test segments in our vertical range */
762  if ( pt->y > ymax || pt->y < ymin )
763  {
764  seg1 = seg2;
765  continue;
766  }
767 
768  side = lw_segment_side(seg1, seg2, pt);
769 
770  /*
771  * A point on the boundary of a ring is not contained.
772  * WAS: if (fabs(side) < 1e-12), see #852
773  */
774  if ( (side == 0) && lw_pt_in_seg(pt, seg1, seg2) )
775  {
776  return LW_BOUNDARY;
777  }
778 
779  /*
780  * If the point is to the left of the line, and it's rising,
781  * then the line is to the right of the point and
782  * circling counter-clockwise, so increment.
783  */
784  if ( (side < 0) && (seg1->y <= pt->y) && (pt->y < seg2->y) )
785  {
786  wn++;
787  }
788 
789  /*
790  * If the point is to the right of the line, and it's falling,
791  * then the line is to the right of the point and circling
792  * clockwise, so decrement.
793  */
794  else if ( (side > 0) && (seg2->y <= pt->y) && (pt->y < seg1->y) )
795  {
796  wn--;
797  }
798 
799  seg1 = seg2;
800  }
801 
802  /* Sent out the winding number for calls that are building on this as a primitive */
803  if ( winding_number )
804  *winding_number = wn;
805 
806  /* Outside */
807  if (wn == 0)
808  {
809  return LW_OUTSIDE;
810  }
811 
812  /* Inside */
813  return LW_INSIDE;
814 }
#define FP_MIN(A, B)
unsigned int uint32_t
Definition: uthash.h:78
double x
Definition: liblwgeom.h:330
int p2d_same(const POINT2D *p1, const POINT2D *p2)
Definition: lwalgorithm.c:49
#define LW_INSIDE
Constants for point-in-polygon return values.
double y
Definition: liblwgeom.h:330
#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:190
#define FP_MAX(A, B)
const POINT2D * getPoint2d_cp(const POINTARRAY *pa, uint32_t n)
Returns a POINT2D pointer into the POINTARRAY serialized_ptlist, suitable for reading from...
Definition: lwgeom_api.c:364
uint32_t npoints
Definition: liblwgeom.h:373
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