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

geom1	the geometry to snap
geom2	the geometry to snap to
tolerance	the distance under which vertices and segments are snapped

Requires GEOS-3.3.0+

Definition at line 1529 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(), and LWGEOM::srid.

Referenced by _lwt_toposnap(), and ST_Snap().

{
        int srid, is3d;
        GEOSGeometry *g1, *g2, *g3;
        LWGEOM* out;

        srid = 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 = (GEOSGeometry *)LWGEOM2GEOS(geom1, 0);
        if ( 0 == g1 )   /* exception thrown at construction */
        {
                lwerror("First argument geometry could not be converted to GEOS: %s", lwgeom_geos_errmsg);
                return NULL;
        }

        g2 = (GEOSGeometry *)LWGEOM2GEOS(geom2, 0);
        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 = GEOSSnap(g1, g2, tolerance);
        if (g3 == NULL)
        {
                GEOSGeom_destroy(g1);
                GEOSGeom_destroy(g2);
                lwerror("GEOSSnap: %s", lwgeom_geos_errmsg);
                return NULL;
        }

        GEOSGeom_destroy(g1);
        GEOSGeom_destroy(g2);

        GEOSSetSRID(g3, srid);
        out = GEOS2LWGEOM(g3, is3d);
        if (out == NULL)
        {
                GEOSGeom_destroy(g3);
                lwerror("GEOSSnap() threw an error (result LWGEOM geometry formation)!");
                return NULL;
        }
        GEOSGeom_destroy(g3);

        return out;
}

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