ST_FrechetDistance()

Datum ST_FrechetDistance

(

PG_FUNCTION_ARGS

)

Definition at line 273 of file postgis/lwgeom_geos.c.

{
#if POSTGIS_GEOS_VERSION < 37
 
        lwpgerror("The GEOS version this PostGIS binary "
                                        "was compiled against (%d) doesn't support "
                                        "'GEOSFechetDistance' function (3.7.0+ required)",
                                        POSTGIS_GEOS_VERSION);
        PG_RETURN_NULL();
 
#else /* POSTGIS_GEOS_VERSION >= 37 */
        GSERIALIZED *geom1;
        GSERIALIZED *geom2;
        GEOSGeometry *g1;
        GEOSGeometry *g2;
        double densifyFrac;
        double result;
        int retcode;
 
        geom1 = PG_GETARG_GSERIALIZED_P(0);
        geom2 = PG_GETARG_GSERIALIZED_P(1);
        densifyFrac = PG_GETARG_FLOAT8(2);
 
        if ( gserialized_is_empty(geom1) || gserialized_is_empty(geom2) )
                PG_RETURN_NULL();
 
        initGEOS(lwpgnotice, lwgeom_geos_error);
 
        g1 = POSTGIS2GEOS(geom1);
        if (!g1)
                HANDLE_GEOS_ERROR("First argument geometry could not be converted to GEOS");
 
        g2 = POSTGIS2GEOS(geom2);
        if (!g2)
        {
                GEOSGeom_destroy(g1);
                HANDLE_GEOS_ERROR("Second argument geometry could not be converted to GEOS");
        }
 
        if (densifyFrac <= 0.0)
        {
                retcode = GEOSFrechetDistance(g1, g2, &result);
        }
        else
        {
                retcode = GEOSFrechetDistanceDensify(g1, g2, densifyFrac, &result);
        }
 
        GEOSGeom_destroy(g1);
        GEOSGeom_destroy(g2);
 
        if (retcode == 0) HANDLE_GEOS_ERROR("GEOSFrechetDistance");
 
        PG_FREE_IF_COPY(geom1, 0);
        PG_FREE_IF_COPY(geom2, 1);
 
        PG_RETURN_FLOAT8(result);
 
#endif /* POSTGIS_GEOS_VERSION >= 37 */
}

References gserialized_is_empty(), HANDLE_GEOS_ERROR, lwgeom_geos_error(), POSTGIS2GEOS(), POSTGIS_GEOS_VERSION, and result.

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