PostGIS  3.1.6dev-r@@SVN_REVISION@@

◆ lwmpoly_to_points()

LWMPOINT* lwmpoly_to_points ( const LWMPOLY lwmpoly,
uint32_t  npoints,
int32_t  seed 
)

Definition at line 1809 of file liblwgeom/lwgeom_geos.c.

1810 {
1811  const LWGEOM* lwgeom = (LWGEOM*)lwmpoly;
1812  double area;
1813  uint32_t i;
1814  LWMPOINT* mpt = NULL;
1815 
1816  if (lwgeom_get_type(lwgeom) != MULTIPOLYGONTYPE)
1817  {
1818  lwerror("%s: only multipolygons supported", __func__);
1819  return NULL;
1820  }
1821  if (npoints == 0 || lwgeom_is_empty(lwgeom)) return NULL;
1822 
1823  area = lwgeom_area(lwgeom);
1824 
1825  for (i = 0; i < lwmpoly->ngeoms; i++)
1826  {
1827  double sub_area = lwpoly_area(lwmpoly->geoms[i]);
1828  int sub_npoints = lround(npoints * sub_area / area);
1829  if (sub_npoints > 0)
1830  {
1831  LWMPOINT* sub_mpt = lwpoly_to_points(lwmpoly->geoms[i], sub_npoints, seed);
1832  if (!mpt)
1833  mpt = sub_mpt;
1834  else
1835  {
1836  uint32_t j;
1837  for (j = 0; j < sub_mpt->ngeoms; j++)
1838  mpt = lwmpoint_add_lwpoint(mpt, sub_mpt->geoms[j]);
1839  /* Just free the shell, leave the underlying lwpoints alone, as they are now owned by
1840  * the returning multipoint */
1841  lwfree(sub_mpt->geoms);
1842  lwgeom_release((LWGEOM*)sub_mpt);
1843  }
1844  }
1845  }
1846  return mpt;
1847 }
LWMPOINT * lwpoly_to_points(const LWPOLY *lwpoly, uint32_t npoints, int32_t seed)
LWMPOINT * lwmpoint_add_lwpoint(LWMPOINT *mobj, const LWPOINT *obj)
Definition: lwmpoint.c:45
double lwgeom_area(const LWGEOM *geom)
Definition: lwgeom.c:1862
#define MULTIPOLYGONTYPE
Definition: liblwgeom.h:121
void lwfree(void *mem)
Definition: lwutil.c:242
void lwgeom_release(LWGEOM *lwgeom)
Free the containing LWGEOM and the associated BOX.
Definition: lwgeom.c:451
double lwpoly_area(const LWPOLY *poly)
Find the area of the outer ring - sum (area of inner rings).
Definition: lwpoly.c:434
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:190
static uint32_t lwgeom_get_type(const LWGEOM *geom)
Return LWTYPE number.
Definition: lwinline.h:145
static int lwgeom_is_empty(const LWGEOM *geom)
Return true or false depending on whether a geometry is an "empty" geometry (no vertices members)
Definition: lwinline.h:203
uint32_t ngeoms
Definition: liblwgeom.h:552
LWPOINT ** geoms
Definition: liblwgeom.h:547
uint32_t ngeoms
Definition: liblwgeom.h:580
LWPOLY ** geoms
Definition: liblwgeom.h:575

References LWMPOINT::geoms, LWMPOLY::geoms, lwerror(), lwfree(), lwgeom_area(), lwgeom_get_type(), lwgeom_is_empty(), lwgeom_release(), lwmpoint_add_lwpoint(), lwpoly_area(), lwpoly_to_points(), MULTIPOLYGONTYPE, LWMPOINT::ngeoms, and LWMPOLY::ngeoms.

Referenced by lwgeom_to_points().

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