shapeObj *msGEOSSymDifference(shapeObj *shape1, shapeObj *shape2)
{
#ifdef USE_GEOS
GEOSGeom g1, g2, g3;
if(!shape1 || !shape2)
return NULL;
if(!shape1->geometry) /* if no geometry for the shape then build one */
shape1->geometry = (GEOSGeom) msGEOSShape2Geometry(shape1);
g1 = (GEOSGeom) shape1->geometry;
if(!g1) return NULL;
if(!shape2->geometry) /* if no geometry for the shape then build one */
shape2->geometry = (GEOSGeom) msGEOSShape2Geometry(shape2);
g2 = (GEOSGeom) shape2->geometry;
if(!g2) return NULL;
g3 = GEOSSymDifference(g1, g2);
return msGEOSGeometry2Shape(g3);
#else
msSetError(MS_GEOSERR, "GEOS support is not available.", "msGEOSSymDifference()");
return NULL;
#endif
}
char *msudf_symDifference(UDF_INIT *initid,UDF_ARGS *args, char *buf,
unsigned long *length, char *is_null, char *error)
{
char *result;
GEOSGeom geomFirst,geomSecond,geomResult;
DEBUG("msudf_symDifference");
geomFirst = msudf_getGeometry((unsigned char *)args->args[0],args->lengths[0]);
if (geomFirst == NULL) {
strcpy(error,"Invalid geometry.");
*is_null = 1;
return 0;
}
geomSecond = msudf_getGeometry((unsigned char *)args->args[1],args->lengths[1]);
if (geomSecond == NULL) {
GEOSGeom_destroy(geomFirst);
strcpy(error,"Invalid geometry.");
*is_null = 1;
return 0;
}
geomResult = GEOSSymDifference(geomFirst,geomSecond);
if (geomResult!= NULL) {
GEOSSetSRID(geomResult,GEOSGetSRID(geomFirst));
result = msudf_returnGeometry(initid,length,geomResult);
GEOSGeom_destroy(geomFirst);
GEOSGeom_destroy(geomSecond);
GEOSGeom_destroy(geomResult);
return result;
} else {
GEOSGeom_destroy(geomFirst);
GEOSGeom_destroy(geomSecond);
*is_null = 1;
return NULL;
}
}
GEOSGeometry*
LWGEOM_GEOS_buildArea(const GEOSGeometry* geom_in)
{
GEOSGeometry *tmp;
GEOSGeometry *geos_result, *shp;
GEOSGeometry const *vgeoms[1];
uint32_t i, ngeoms;
int srid = GEOSGetSRID(geom_in);
vgeoms[0] = geom_in;
geos_result = GEOSPolygonize(vgeoms, 1);
LWDEBUGF(3, "GEOSpolygonize returned @ %p", geos_result);
/* Null return from GEOSpolygonize (an exception) */
if ( ! geos_result ) return 0;
/*
* We should now have a collection
*/
#if PARANOIA_LEVEL > 0
if ( GEOSGeometryTypeId(geos_result) != COLLECTIONTYPE )
{
GEOSGeom_destroy(geos_result);
lwerror("Unexpected return from GEOSpolygonize");
return 0;
}
#endif
ngeoms = GEOSGetNumGeometries(geos_result);
LWDEBUGF(3, "GEOSpolygonize: ngeoms in polygonize output: %d", ngeoms);
LWDEBUGF(3, "GEOSpolygonize: polygonized:%s",
lwgeom_to_ewkt(GEOS2LWGEOM(geos_result, 0)));
/*
* No geometries in collection, early out
*/
if ( ngeoms == 0 )
{
GEOSSetSRID(geos_result, srid);
return geos_result;
}
/*
* Return first geometry if we only have one in collection,
* to avoid the unnecessary Geometry clone below.
*/
if ( ngeoms == 1 )
{
tmp = (GEOSGeometry *)GEOSGetGeometryN(geos_result, 0);
if ( ! tmp )
{
GEOSGeom_destroy(geos_result);
return 0; /* exception */
}
shp = GEOSGeom_clone(tmp);
GEOSGeom_destroy(geos_result); /* only safe after the clone above */
GEOSSetSRID(shp, srid);
return shp;
}
/*
* Iteratively invoke symdifference on outer rings
* as suggested by Carl Anderson:
* postgis-devel/2005-December/001805.html
*/
shp = NULL;
for (i=0; i<ngeoms; ++i)
{
GEOSGeom extring;
GEOSCoordSeq sq;
/*
* Construct a Polygon from geometry i exterior ring
* We don't use GEOSGeom_clone on the ExteriorRing
* due to a bug in CAPI contained in GEOS 2.2 branch
* failing to properly return a LinearRing from
* a LinearRing clone.
*/
sq=GEOSCoordSeq_clone(GEOSGeom_getCoordSeq(
GEOSGetExteriorRing(GEOSGetGeometryN( geos_result, i))
));
extring = GEOSGeom_createPolygon(
GEOSGeom_createLinearRing(sq),
NULL, 0
);
if ( extring == NULL ) /* exception */
{
lwerror("GEOSCreatePolygon threw an exception");
return 0;
}
if ( shp == NULL )
{
shp = extring;
LWDEBUGF(3, "GEOSpolygonize: shp:%s",
lwgeom_to_ewkt(GEOS2LWGEOM(shp, 0)));
}
else
{
tmp = GEOSSymDifference(shp, extring);
LWDEBUGF(3, "GEOSpolygonize: SymDifference(%s, %s):%s",
lwgeom_to_ewkt(GEOS2LWGEOM(shp, 0)),
lwgeom_to_ewkt(GEOS2LWGEOM(extring, 0)),
lwgeom_to_ewkt(GEOS2LWGEOM(tmp, 0))
);
GEOSGeom_destroy(shp);
GEOSGeom_destroy(extring);
shp = tmp;
}
}
GEOSGeom_destroy(geos_result);
GEOSSetSRID(shp, srid);
return shp;
}
LWGEOM *
lwgeom_symdifference(const LWGEOM* geom1, const LWGEOM* geom2)
{
GEOSGeometry *g1, *g2, *g3;
LWGEOM *result;
int is3d;
int srid;
/* A.SymDifference(Empty) == A */
if ( lwgeom_is_empty(geom2) )
return lwgeom_clone(geom1);
/* Empty.DymDifference(B) == Empty */
if ( lwgeom_is_empty(geom1) )
return lwgeom_clone(geom1);
/* ensure srids are identical */
srid = (int)(geom1->srid);
error_if_srid_mismatch(srid, (int)(geom2->srid));
is3d = (FLAGS_GET_Z(geom1->flags) || FLAGS_GET_Z(geom2->flags)) ;
initGEOS(lwnotice, lwgeom_geos_error);
g1 = LWGEOM2GEOS(geom1);
if ( 0 == g1 ) /* exception thrown at construction */
{
lwerror("First argument geometry could not be converted to GEOS: %s", lwgeom_geos_errmsg);
return NULL;
}
g2 = LWGEOM2GEOS(geom2);
if ( 0 == g2 ) /* exception thrown at construction */
{
lwerror("Second argument geometry could not be converted to GEOS: %s", lwgeom_geos_errmsg);
GEOSGeom_destroy(g1);
return NULL;
}
g3 = GEOSSymDifference(g1,g2);
if (g3 == NULL)
{
GEOSGeom_destroy(g1);
GEOSGeom_destroy(g2);
lwerror("GEOSSymDifference: %s", lwgeom_geos_errmsg);
return NULL; /*never get here */
}
LWDEBUGF(3, "result: %s", GEOSGeomToWKT(g3));
GEOSSetSRID(g3, srid);
result = GEOS2LWGEOM(g3, is3d);
if (result == NULL)
{
GEOSGeom_destroy(g1);
GEOSGeom_destroy(g2);
GEOSGeom_destroy(g3);
lwerror("GEOS symdifference() threw an error (result postgis geometry formation)!");
return NULL ; /*never get here */
}
GEOSGeom_destroy(g1);
GEOSGeom_destroy(g2);
GEOSGeom_destroy(g3);
return result;
}
