lwgeom_buildarea()

LWGEOM* lwgeom_buildarea

(

const LWGEOM *

geom

)

Take a geometry and return an areal geometry (Polygon or MultiPolygon).

Actually a wrapper around GEOSpolygonize, transforming the resulting collection into a valid polygon Geometry.

Definition at line 1421 of file liblwgeom/lwgeom_geos.c.

{
        LWGEOM* result;
        int32_t srid = RESULT_SRID(geom);
        uint8_t is3d = FLAGS_GET_Z(geom->flags);
        GEOSGeometry *g1, *g3;
 
        if (srid == SRID_INVALID) return NULL;
 
        /* Can't build an area from an empty! */
        if (lwgeom_is_empty(geom)) return (LWGEOM*)lwpoly_construct_empty(srid, is3d, 0);
 
        initGEOS(lwnotice, lwgeom_geos_error);
 
        if (!(g1 = LWGEOM2GEOS(geom, AUTOFIX))) GEOS_FAIL();
 
#if POSTGIS_GEOS_VERSION < 30800
        g3 = LWGEOM_GEOS_buildArea(g1);
#else
        g3 = GEOSBuildArea(g1);
#endif
 
        if (!g3) GEOS_FREE_AND_FAIL(g1);
        GEOSSetSRID(g3, srid);
 
        /* If no geometries are in result collection, return NULL */
        if (GEOSGetNumGeometries(g3) == 0)
        {
                GEOS_FREE(g1);
                return NULL;
        }
 
        if (!(result = GEOS2LWGEOM(g3, is3d)))
                GEOS_FREE_AND_FAIL(g1, g3);
 
        GEOS_FREE(g1, g3);
 
        return result;
}

References AUTOFIX, LWGEOM::flags, FLAGS_GET_Z, GEOS2LWGEOM(), GEOS_FAIL, GEOS_FREE, GEOS_FREE_AND_FAIL, LWGEOM2GEOS(), lwgeom_geos_error(), lwgeom_is_empty(), lwnotice(), lwpoly_construct_empty(), result, RESULT_SRID, and SRID_INVALID.

Referenced by _lwt_FaceByEdges(), buildarea1(), buildarea2(), buildarea3(), buildarea4(), buildarea4b(), buildarea5(), buildarea6(), buildarea7(), and ST_BuildArea().

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