PostGIS  2.5.0dev-r@@SVN_REVISION@@
LWGEOM* lwgeom_difference ( const LWGEOM geom1,
const LWGEOM geom2 
)

Definition at line 791 of file liblwgeom/lwgeom_geos.c.

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

Referenced by _lwt_AddLine(), and geos_difference().

792 {
793  GEOSGeometry *g1, *g2, *g3;
794  LWGEOM *result;
795  int is3d;
796  int srid;
797 
798  /* A.Difference(Empty) == A */
799  if ( lwgeom_is_empty(geom2) )
800  return lwgeom_clone_deep(geom1);
801 
802  /* Empty.Intersection(A) == Empty */
803  if ( lwgeom_is_empty(geom1) )
804  return lwgeom_clone_deep(geom1);
805 
806  /* ensure srids are identical */
807  srid = (int)(geom1->srid);
808  error_if_srid_mismatch(srid, (int)(geom2->srid));
809 
810  is3d = (FLAGS_GET_Z(geom1->flags) || FLAGS_GET_Z(geom2->flags)) ;
811 
812  initGEOS(lwnotice, lwgeom_geos_error);
813 
814  g1 = LWGEOM2GEOS(geom1, 0);
815  if ( 0 == g1 ) /* exception thrown at construction */
816  {
817  lwerror("First argument geometry could not be converted to GEOS: %s", lwgeom_geos_errmsg);
818  return NULL;
819  }
820 
821  g2 = LWGEOM2GEOS(geom2, 0);
822  if ( 0 == g2 ) /* exception thrown at construction */
823  {
824  GEOSGeom_destroy(g1);
825  lwerror("Second argument geometry could not be converted to GEOS: %s", lwgeom_geos_errmsg);
826  return NULL;
827  }
828 
829  g3 = GEOSDifference(g1,g2);
830 
831  if (g3 == NULL)
832  {
833  GEOSGeom_destroy(g1);
834  GEOSGeom_destroy(g2);
835  lwerror("GEOSDifference: %s", lwgeom_geos_errmsg);
836  return NULL ; /* never get here */
837  }
838 
839  LWDEBUGF(3, "result: %s", GEOSGeomToWKT(g3) ) ;
840 
841  GEOSSetSRID(g3, srid);
842 
843  result = GEOS2LWGEOM(g3, is3d);
844 
845  if (result == NULL)
846  {
847  GEOSGeom_destroy(g1);
848  GEOSGeom_destroy(g2);
849  GEOSGeom_destroy(g3);
850  lwerror("Error performing difference: GEOS2LWGEOM: %s",
852  return NULL; /* never get here */
853  }
854 
855  GEOSGeom_destroy(g1);
856  GEOSGeom_destroy(g2);
857  GEOSGeom_destroy(g3);
858 
859  /* compressType(result); */
860 
861  return result;
862 }
void lwnotice(const char *fmt,...)
Write a notice out to the notice handler.
Definition: lwutil.c:177
uint8_t flags
Definition: liblwgeom.h:396
char lwgeom_geos_errmsg[LWGEOM_GEOS_ERRMSG_MAXSIZE]
LWGEOM * lwgeom_clone_deep(const LWGEOM *lwgeom)
Deep clone an LWGEOM, everything is copied.
Definition: lwgeom.c:513
void error_if_srid_mismatch(int srid1, int srid2)
Definition: lwutil.c:338
int32_t srid
Definition: liblwgeom.h:398
void lwgeom_geos_error(const char *fmt,...)
#define FLAGS_GET_Z(flags)
Macros for manipulating the 'flags' byte.
Definition: liblwgeom.h:139
GEOSGeometry * LWGEOM2GEOS(const LWGEOM *lwgeom, int autofix)
LWGEOM * GEOS2LWGEOM(const GEOSGeometry *geom, char want3d)
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:1386
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:88
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:190

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