geography_distance()

Datum geography_distance

(

PG_FUNCTION_ARGS

)

Definition at line 205 of file geography_measurement.c.

References SPHEROID::a, SPHEROID::b, distance(), error_if_srid_mismatch(), geography_distance_cache(), geography_dwithin(), gserialized_get_srid(), gserialized_is_empty(), INVMINDIST, LW_FAILURE, lwgeom_distance_spheroid(), lwgeom_free(), lwgeom_from_gserialized(), PG_FUNCTION_INFO_V1(), SPHEROID::radius, and s.

Referenced by geography_distance_uncached().

{
        GSERIALIZED* g1 = NULL;
        GSERIALIZED* g2 = NULL;
        double distance;
        double tolerance = 0.0;
        bool use_spheroid = true;
        SPHEROID s;

        /* Get our geometry objects loaded into memory. */
        g1 = PG_GETARG_GSERIALIZED_P(0);
        g2 = PG_GETARG_GSERIALIZED_P(1);

        /* Read our tolerance value. */
        if ( PG_NARGS() > 2 && ! PG_ARGISNULL(2) )
                tolerance = PG_GETARG_FLOAT8(2);

        /* Read our calculation type. */
        if ( PG_NARGS() > 3 && ! PG_ARGISNULL(3) )
                use_spheroid = PG_GETARG_BOOL(3);

        error_if_srid_mismatch(gserialized_get_srid(g1), gserialized_get_srid(g2));

        /* Initialize spheroid */
        spheroid_init_from_srid(fcinfo, gserialized_get_srid(g1), &s);

        /* Set to sphere if requested */
        if ( ! use_spheroid )
                s.a = s.b = s.radius;

        /* Return NULL on empty arguments. */
        if ( gserialized_is_empty(g1) || gserialized_is_empty(g2) )
        {
                PG_FREE_IF_COPY(g1, 0);
                PG_FREE_IF_COPY(g2, 1);
                PG_RETURN_NULL();
        }

        /* Do the brute force calculation if the cached calculation doesn't tick over */
        if ( LW_FAILURE == geography_distance_cache(fcinfo, g1, g2, &s, &distance) )
        {
                LWGEOM* lwgeom1 = lwgeom_from_gserialized(g1);
                LWGEOM* lwgeom2 = lwgeom_from_gserialized(g2);
                distance = lwgeom_distance_spheroid(lwgeom1, lwgeom2, &s, tolerance);
                lwgeom_free(lwgeom1);
                lwgeom_free(lwgeom2);
        }

        /* Clean up */
        PG_FREE_IF_COPY(g1, 0);
        PG_FREE_IF_COPY(g2, 1);

        /* Knock off any funny business at the nanometer level, ticket #2168 */
        distance = round(distance * INVMINDIST) / INVMINDIST;

        /* Something went wrong, negative return... should already be eloged, return NULL */
        if ( distance < 0.0 )
        {
                elog(ERROR, "distance returned negative!");
                PG_RETURN_NULL();
        }

        PG_RETURN_FLOAT8(distance);
}

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