PostGIS  2.2.7dev-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 2387 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().

2388 {
2389  int i;
2390  int in_hole_count = 0;
2391  POINT3D p;
2392  GEOGRAPHIC_POINT gpt_to_test;
2393  POINT2D pt_outside;
2394  GBOX gbox;
2395  gbox.flags = 0;
2396 
2397  /* Nulls and empties don't contain anything! */
2398  if ( ! poly || lwgeom_is_empty((LWGEOM*)poly) )
2399  {
2400  LWDEBUG(4,"returning false, geometry is empty or null");
2401  return LW_FALSE;
2402  }
2403 
2404  /* Make sure we have boxes */
2405  if ( poly->bbox )
2406  gbox = *(poly->bbox);
2407  else
2408  lwgeom_calculate_gbox_geodetic((LWGEOM*)poly, &gbox);
2409 
2410  /* Point not in box? Done! */
2411  geographic_point_init(pt_to_test->x, pt_to_test->y, &gpt_to_test);
2412  geog2cart(&gpt_to_test, &p);
2413  if ( ! gbox_contains_point3d(&gbox, &p) )
2414  {
2415  LWDEBUG(4, "the point is not in the box!");
2416  return LW_FALSE;
2417  }
2418 
2419  /* Calculate our outside point from the gbox */
2420  gbox_pt_outside(&gbox, &pt_outside);
2421 
2422  LWDEBUGF(4, "pt_outside POINT(%.18g %.18g)", pt_outside.x, pt_outside.y);
2423  LWDEBUGF(4, "pt_to_test POINT(%.18g %.18g)", pt_to_test->x, pt_to_test->y);
2424  LWDEBUGF(4, "polygon %s", lwgeom_to_ewkt((LWGEOM*)poly));
2425  LWDEBUGF(4, "gbox %s", gbox_to_string(&gbox));
2426 
2427  /* Not in outer ring? We're done! */
2428  if ( ! ptarray_contains_point_sphere(poly->rings[0], &pt_outside, pt_to_test) )
2429  {
2430  LWDEBUG(4,"returning false, point is outside ring");
2431  return LW_FALSE;
2432  }
2433 
2434  LWDEBUGF(4, "testing %d rings", poly->nrings);
2435 
2436  /* But maybe point is in a hole... */
2437  for ( i = 1; i < poly->nrings; i++ )
2438  {
2439  LWDEBUGF(4, "ring test loop %d", i);
2440  /* Count up hole containment. Odd => outside boundary. */
2441  if ( ptarray_contains_point_sphere(poly->rings[i], &pt_outside, pt_to_test) )
2442  in_hole_count++;
2443  }
2444 
2445  LWDEBUGF(4, "in_hole_count == %d", in_hole_count);
2446 
2447  if ( in_hole_count % 2 )
2448  {
2449  LWDEBUG(4,"returning false, inner ring containment count is odd");
2450  return LW_FALSE;
2451  }
2452 
2453  LWDEBUG(4,"returning true, inner ring containment count is even");
2454  return LW_TRUE;
2455 }
char * gbox_to_string(const GBOX *gbox)
Allocate a string representation of the GBOX, based on dimensionality of flags.
Definition: g_box.c:369
char * lwgeom_to_ewkt(const LWGEOM *lwgeom)
Return an alloced string.
Definition: lwgeom.c:469
int gbox_contains_point3d(const GBOX *gbox, const POINT3D *pt)
Return true if the point is inside the gbox.
Definition: g_box.c:224
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:50
GBOX * bbox
Definition: liblwgeom.h:437
Point in spherical coordinates on the world.
Definition: lwgeodetic.h:32
double x
Definition: liblwgeom.h:312
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:3204
#define LW_FALSE
Definition: liblwgeom.h:62
#define LW_TRUE
Return types for functions with status returns.
Definition: liblwgeom.h:61
int lwgeom_calculate_gbox_geodetic(const LWGEOM *geom, GBOX *gbox)
Calculate the geodetic bounding box for an LWGEOM.
Definition: lwgeodetic.c:2615
POINTARRAY ** rings
Definition: liblwgeom.h:441
int nrings
Definition: liblwgeom.h:439
double y
Definition: liblwgeom.h:312
uint8_t flags
Definition: liblwgeom.h:275
void geog2cart(const GEOGRAPHIC_POINT *g, POINT3D *p)
Convert spherical coordinates to cartesion coordinates on unit sphere.
Definition: lwgeodetic.c:354
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:1444
void geographic_point_init(double lon, double lat, GEOGRAPHIC_POINT *g)
Initialize a geographic point.
Definition: lwgeodetic.c:156
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:1297
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:55

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