PostGIS  2.3.7dev-r@@SVN_REVISION@@
int lwpoly_covers_point2d ( const LWPOLY poly,
const POINT2D pt_to_test 
)

Given a polygon (lon/lat decimal degrees) and point (lon/lat decimal degrees) and a guaranteed outside point (lon/lat decimal degrees) (calculate with gbox_pt_outside()) return LW_TRUE if point is inside or on edge of polygon.

Definition at line 2398 of file lwgeodetic.c.

References LWPOLY::bbox, GBOX::flags, gbox_contains_point3d(), gbox_pt_outside(), gbox_to_string(), geog2cart(), geographic_point_init(), LW_FALSE, LW_TRUE, LWDEBUG, LWDEBUGF, lwgeom_calculate_gbox_geodetic(), lwgeom_is_empty(), lwgeom_to_ewkt(), LWPOLY::nrings, ptarray_contains_point_sphere(), LWPOLY::rings, POINT2D::x, and POINT2D::y.

Referenced by lwgeom_covers_lwgeom_sphere(), lwgeom_distance_spheroid(), test_lwpoly_covers_point2d(), and test_tree_circ_pip2().

2399 {
2400  int i;
2401  int in_hole_count = 0;
2402  POINT3D p;
2403  GEOGRAPHIC_POINT gpt_to_test;
2404  POINT2D pt_outside;
2405  GBOX gbox;
2406  gbox.flags = 0;
2407 
2408  /* Nulls and empties don't contain anything! */
2409  if ( ! poly || lwgeom_is_empty((LWGEOM*)poly) )
2410  {
2411  LWDEBUG(4,"returning false, geometry is empty or null");
2412  return LW_FALSE;
2413  }
2414 
2415  /* Make sure we have boxes */
2416  if ( poly->bbox )
2417  gbox = *(poly->bbox);
2418  else
2419  lwgeom_calculate_gbox_geodetic((LWGEOM*)poly, &gbox);
2420 
2421  /* Point not in box? Done! */
2422  geographic_point_init(pt_to_test->x, pt_to_test->y, &gpt_to_test);
2423  geog2cart(&gpt_to_test, &p);
2424  if ( ! gbox_contains_point3d(&gbox, &p) )
2425  {
2426  LWDEBUG(4, "the point is not in the box!");
2427  return LW_FALSE;
2428  }
2429 
2430  /* Calculate our outside point from the gbox */
2431  gbox_pt_outside(&gbox, &pt_outside);
2432 
2433  LWDEBUGF(4, "pt_outside POINT(%.18g %.18g)", pt_outside.x, pt_outside.y);
2434  LWDEBUGF(4, "pt_to_test POINT(%.18g %.18g)", pt_to_test->x, pt_to_test->y);
2435  LWDEBUGF(4, "polygon %s", lwgeom_to_ewkt((LWGEOM*)poly));
2436  LWDEBUGF(4, "gbox %s", gbox_to_string(&gbox));
2437 
2438  /* Not in outer ring? We're done! */
2439  if ( ! ptarray_contains_point_sphere(poly->rings[0], &pt_outside, pt_to_test) )
2440  {
2441  LWDEBUG(4,"returning false, point is outside ring");
2442  return LW_FALSE;
2443  }
2444 
2445  LWDEBUGF(4, "testing %d rings", poly->nrings);
2446 
2447  /* But maybe point is in a hole... */
2448  for ( i = 1; i < poly->nrings; i++ )
2449  {
2450  LWDEBUGF(4, "ring test loop %d", i);
2451  /* Count up hole containment. Odd => outside boundary. */
2452  if ( ptarray_contains_point_sphere(poly->rings[i], &pt_outside, pt_to_test) )
2453  in_hole_count++;
2454  }
2455 
2456  LWDEBUGF(4, "in_hole_count == %d", in_hole_count);
2457 
2458  if ( in_hole_count % 2 )
2459  {
2460  LWDEBUG(4,"returning false, inner ring containment count is odd");
2461  return LW_FALSE;
2462  }
2463 
2464  LWDEBUG(4,"returning true, inner ring containment count is even");
2465  return LW_TRUE;
2466 }
char * gbox_to_string(const GBOX *gbox)
Allocate a string representation of the GBOX, based on dimensionality of flags.
Definition: g_box.c:404
char * lwgeom_to_ewkt(const LWGEOM *lwgeom)
Return an alloced string.
Definition: lwgeom.c:482
int gbox_contains_point3d(const GBOX *gbox, const POINT3D *pt)
Return true if the point is inside the gbox.
Definition: g_box.c:259
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:83
GBOX * bbox
Definition: liblwgeom.h:452
Point in spherical coordinates on the world.
Definition: lwgeodetic.h:47
double x
Definition: liblwgeom.h:327
int ptarray_contains_point_sphere(const POINTARRAY *pa, const POINT2D *pt_outside, const POINT2D *pt_to_test)
This routine returns LW_TRUE if the stabline joining the pt_outside and pt_to_test crosses the ring a...
Definition: lwgeodetic.c:3215
#define LW_FALSE
Definition: liblwgeom.h:76
#define LW_TRUE
Return types for functions with status returns.
Definition: liblwgeom.h:75
int lwgeom_calculate_gbox_geodetic(const LWGEOM *geom, GBOX *gbox)
Calculate the geodetic bounding box for an LWGEOM.
Definition: lwgeodetic.c:2626
POINTARRAY ** rings
Definition: liblwgeom.h:456
int nrings
Definition: liblwgeom.h:454
double y
Definition: liblwgeom.h:327
uint8_t flags
Definition: liblwgeom.h:290
void geog2cart(const GEOGRAPHIC_POINT *g, POINT3D *p)
Convert spherical coordinates to cartesion coordinates on unit sphere.
Definition: lwgeodetic.c:369
void gbox_pt_outside(const GBOX *gbox, POINT2D *pt_outside)
Given a unit geocentric gbox, return a lon/lat (degrees) coordinate point point that is guaranteed to...
Definition: lwgeodetic.c:1461
void geographic_point_init(double lon, double lat, GEOGRAPHIC_POINT *g)
Initialize a geographic point.
Definition: lwgeodetic.c:171
int lwgeom_is_empty(const LWGEOM *geom)
Return true or false depending on whether a geometry is an "empty" geometry (no vertices members) ...
Definition: lwgeom.c:1310
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:88

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