PostGIS  2.5.0dev-r@@SVN_REVISION@@

◆ lwmpoly_to_points()

LWMPOINT* lwmpoly_to_points ( const LWMPOLY lwmpoly,
uint32_t  npoints 
)

Definition at line 1748 of file liblwgeom/lwgeom_geos.c.

References area(), 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().

1749 {
1750  const LWGEOM* lwgeom = (LWGEOM*)lwmpoly;
1751  double area;
1752  uint32_t i;
1753  LWMPOINT* mpt = NULL;
1754 
1755  if (lwgeom_get_type(lwgeom) != MULTIPOLYGONTYPE)
1756  {
1757  lwerror("%s: only multipolygons supported", __func__);
1758  return NULL;
1759  }
1760  if (npoints == 0 || lwgeom_is_empty(lwgeom)) return NULL;
1761 
1762  area = lwgeom_area(lwgeom);
1763 
1764  for (i = 0; i < lwmpoly->ngeoms; i++)
1765  {
1766  double sub_area = lwpoly_area(lwmpoly->geoms[i]);
1767  int sub_npoints = lround(npoints * sub_area / area);
1768  if (sub_npoints > 0)
1769  {
1770  LWMPOINT* sub_mpt = lwpoly_to_points(lwmpoly->geoms[i], sub_npoints);
1771  if (!mpt)
1772  mpt = sub_mpt;
1773  else
1774  {
1775  uint32_t j;
1776  for (j = 0; j < sub_mpt->ngeoms; j++)
1777  mpt = lwmpoint_add_lwpoint(mpt, sub_mpt->geoms[j]);
1778  /* Just free the shell, leave the underlying lwpoints alone, as they are now owned by
1779  * the returning multipoint */
1780  lwfree(sub_mpt->geoms);
1781  lwgeom_release((LWGEOM*)sub_mpt);
1782  }
1783  }
1784  }
1785  return mpt;
1786 }
uint32_t ngeoms
Definition: liblwgeom.h:467
void lwfree(void *mem)
Definition: lwutil.c:244
uint32_t lwgeom_get_type(const LWGEOM *geom)
Return LWTYPE number.
Definition: lwgeom.c:922
uint32_t ngeoms
Definition: liblwgeom.h:493
Datum area(PG_FUNCTION_ARGS)
unsigned int uint32_t
Definition: uthash.h:78
LWMPOINT * lwpoly_to_points(const LWPOLY *lwpoly, uint32_t npoints)
LWPOLY ** geoms
Definition: liblwgeom.h:495
LWPOINT ** geoms
Definition: liblwgeom.h:469
double lwpoly_area(const LWPOLY *poly)
Find the area of the outer ring - sum (area of inner rings).
Definition: lwpoly.c:441
#define MULTIPOLYGONTYPE
Definition: liblwgeom.h:89
double lwgeom_area(const LWGEOM *geom)
Definition: lwgeom.c:1856
LWMPOINT * lwmpoint_add_lwpoint(LWMPOINT *mobj, const LWPOINT *obj)
Definition: lwmpoint.c:45
void lwgeom_release(LWGEOM *lwgeom)
Free the containing LWGEOM and the associated BOX.
Definition: lwgeom.c:458
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:1392
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:190
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