PostGIS  2.2.8dev-r@@SVN_REVISION@@

◆ lwgeom_snap()

LWGEOM* lwgeom_snap ( const LWGEOM geom1,
const LWGEOM geom2,
double  tolerance 
)

Snap vertices and segments of a geometry to another using a given tolerance.

Parameters
geom1the geometry to snap
geom2the geometry to snap to
tolerancethe distance under which vertices and segments are snapped

Requires GEOS-3.3.0+

Definition at line 1420 of file liblwgeom/lwgeom_geos.c.

References error_if_srid_mismatch(), LWGEOM::flags, FLAGS_GET_Z, GEOS2LWGEOM(), lwerror(), LWGEOM2GEOS(), lwgeom_geos_errmsg, lwgeom_geos_error(), lwnotice(), POSTGIS_GEOS_VERSION, and LWGEOM::srid.

Referenced by _lwt_toposnap(), and ST_Snap().

1421 {
1422 #if POSTGIS_GEOS_VERSION < 33
1423  lwerror("The GEOS version this lwgeom library "
1424  "was compiled against (%d) doesn't support "
1425  "'Snap' function (3.3.0+ required)",
1427  return NULL;
1428 #else /* POSTGIS_GEOS_VERSION >= 33 */
1429 
1430  int srid, is3d;
1431  GEOSGeometry *g1, *g2, *g3;
1432  LWGEOM* out;
1433 
1434  srid = geom1->srid;
1435  error_if_srid_mismatch(srid, (int)(geom2->srid));
1436 
1437  is3d = (FLAGS_GET_Z(geom1->flags) || FLAGS_GET_Z(geom2->flags)) ;
1438 
1439  initGEOS(lwnotice, lwgeom_geos_error);
1440 
1441  g1 = (GEOSGeometry *)LWGEOM2GEOS(geom1, 0);
1442  if ( 0 == g1 ) /* exception thrown at construction */
1443  {
1444  lwerror("First argument geometry could not be converted to GEOS: %s", lwgeom_geos_errmsg);
1445  return NULL;
1446  }
1447 
1448  g2 = (GEOSGeometry *)LWGEOM2GEOS(geom2, 0);
1449  if ( 0 == g2 ) /* exception thrown at construction */
1450  {
1451  lwerror("Second argument geometry could not be converted to GEOS: %s", lwgeom_geos_errmsg);
1452  GEOSGeom_destroy(g1);
1453  return NULL;
1454  }
1455 
1456  g3 = GEOSSnap(g1, g2, tolerance);
1457  if (g3 == NULL)
1458  {
1459  GEOSGeom_destroy(g1);
1460  GEOSGeom_destroy(g2);
1461  lwerror("GEOSSnap: %s", lwgeom_geos_errmsg);
1462  return NULL;
1463  }
1464 
1465  GEOSGeom_destroy(g1);
1466  GEOSGeom_destroy(g2);
1467 
1468  GEOSSetSRID(g3, srid);
1469  out = GEOS2LWGEOM(g3, is3d);
1470  if (out == NULL)
1471  {
1472  GEOSGeom_destroy(g3);
1473  lwerror("GEOSSnap() threw an error (result LWGEOM geometry formation)!");
1474  return NULL;
1475  }
1476  GEOSGeom_destroy(g3);
1477 
1478  return out;
1479 
1480 #endif /* POSTGIS_GEOS_VERSION >= 33 */
1481 }
#define POSTGIS_GEOS_VERSION
Definition: sqldefines.h:10
void lwnotice(const char *fmt,...)
Write a notice out to the notice handler.
Definition: lwutil.c:61
uint8_t flags
Definition: liblwgeom.h:381
char lwgeom_geos_errmsg[LWGEOM_GEOS_ERRMSG_MAXSIZE]
void error_if_srid_mismatch(int srid1, int srid2)
Definition: lwutil.c:341
int32_t srid
Definition: liblwgeom.h:383
void lwgeom_geos_error(const char *fmt,...)
#define FLAGS_GET_Z(flags)
Macros for manipulating the &#39;flags&#39; byte.
Definition: liblwgeom.h:124
GEOSGeometry * LWGEOM2GEOS(const LWGEOM *lwgeom, int autofix)
LWGEOM * GEOS2LWGEOM(const GEOSGeometry *geom, char want3d)
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:74
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