PostGIS  2.5.7dev-r@@SVN_REVISION@@

◆ lwpoly_covers_point2d()

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 2518 of file lwgeodetic.c.

2519 {
2520  uint32_t i;
2521  int in_hole_count = 0;
2522  POINT3D p;
2523  GEOGRAPHIC_POINT gpt_to_test;
2524  POINT2D pt_outside;
2525  GBOX gbox;
2526 #if POSTGIS_DEBUG_LEVEL >= 4
2527  char *geom_ewkt;
2528 #endif
2529  gbox.flags = 0;
2530 
2531  /* Nulls and empties don't contain anything! */
2532  if ( ! poly || lwgeom_is_empty((LWGEOM*)poly) )
2533  {
2534  LWDEBUG(4,"returning false, geometry is empty or null");
2535  return LW_FALSE;
2536  }
2537 
2538  /* Make sure we have boxes */
2539  if ( poly->bbox )
2540  gbox = *(poly->bbox);
2541  else
2542  lwgeom_calculate_gbox_geodetic((LWGEOM*)poly, &gbox);
2543 
2544  /* Point not in box? Done! */
2545  geographic_point_init(pt_to_test->x, pt_to_test->y, &gpt_to_test);
2546  geog2cart(&gpt_to_test, &p);
2547  if ( ! gbox_contains_point3d(&gbox, &p) )
2548  {
2549  LWDEBUG(4, "the point is not in the box!");
2550  return LW_FALSE;
2551  }
2552 
2553  /* Calculate our outside point from the gbox */
2554  lwpoly_pt_outside(poly, &pt_outside);
2555 
2556  LWDEBUGF(4, "pt_outside POINT(%.18g %.18g)", pt_outside.x, pt_outside.y);
2557  LWDEBUGF(4, "pt_to_test POINT(%.18g %.18g)", pt_to_test->x, pt_to_test->y);
2558 #if POSTGIS_DEBUG_LEVEL >= 4
2559  geom_ewkt = lwgeom_to_ewkt((LWGEOM*)poly);
2560  LWDEBUGF(4, "polygon %s", geom_ewkt);
2561  lwfree(geom_ewkt);
2562  geom_ewkt = gbox_to_string(&gbox);
2563  LWDEBUGF(4, "gbox %s", geom_ewkt);
2564  lwfree(geom_ewkt);
2565 #endif
2566 
2567  /* Not in outer ring? We're done! */
2568  if ( ! ptarray_contains_point_sphere(poly->rings[0], &pt_outside, pt_to_test) )
2569  {
2570  LWDEBUG(4,"returning false, point is outside ring");
2571  return LW_FALSE;
2572  }
2573 
2574  LWDEBUGF(4, "testing %d rings", poly->nrings);
2575 
2576  /* But maybe point is in a hole... */
2577  for ( i = 1; i < poly->nrings; i++ )
2578  {
2579  LWDEBUGF(4, "ring test loop %d", i);
2580  /* Count up hole containment. Odd => outside boundary. */
2581  if ( ptarray_contains_point_sphere(poly->rings[i], &pt_outside, pt_to_test) )
2582  in_hole_count++;
2583  }
2584 
2585  LWDEBUGF(4, "in_hole_count == %d", in_hole_count);
2586 
2587  if ( in_hole_count % 2 )
2588  {
2589  LWDEBUG(4,"returning false, inner ring containment count is odd");
2590  return LW_FALSE;
2591  }
2592 
2593  LWDEBUG(4,"returning true, inner ring containment count is even");
2594  return LW_TRUE;
2595 }
int gbox_contains_point3d(const GBOX *gbox, const POINT3D *pt)
Return true if the point is inside the gbox.
Definition: g_box.c:254
char * gbox_to_string(const GBOX *gbox)
Allocate a string representation of the GBOX, based on dimensionality of flags.
Definition: g_box.c:399
#define LW_FALSE
Definition: liblwgeom.h:77
char * lwgeom_to_ewkt(const LWGEOM *lwgeom)
Return an alloced string.
Definition: lwgeom.c:556
void lwfree(void *mem)
Definition: lwutil.c:244
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:1393
#define LW_TRUE
Return types for functions with status returns.
Definition: liblwgeom.h:76
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:3645
int lwgeom_calculate_gbox_geodetic(const LWGEOM *geom, GBOX *gbox)
Calculate the geodetic bounding box for an LWGEOM.
Definition: lwgeodetic.c:3028
int lwpoly_pt_outside(const LWPOLY *poly, POINT2D *pt_outside)
Definition: lwgeodetic.c:1527
void geographic_point_init(double lon, double lat, GEOGRAPHIC_POINT *g)
Initialize a geographic point.
Definition: lwgeodetic.c:180
void geog2cart(const GEOGRAPHIC_POINT *g, POINT3D *p)
Convert spherical coordinates to cartesian coordinates on unit sphere.
Definition: lwgeodetic.c:404
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:83
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:88
uint8_t flags
Definition: liblwgeom.h:294
Point in spherical coordinates on the world.
Definition: lwgeodetic.h:53
GBOX * bbox
Definition: liblwgeom.h:401
double y
Definition: liblwgeom.h:331
double x
Definition: liblwgeom.h:331
unsigned int uint32_t
Definition: uthash.h:78

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

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

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