geography_azimuth()

Datum geography_azimuth

(

PG_FUNCTION_ARGS

)

Definition at line 1010 of file geography_measurement.c.

References geography_segmentize(), gserialized_get_srid(), gserialized_get_type(), lwgeom_as_lwpoint(), lwgeom_azumith_spheroid(), lwgeom_free(), lwgeom_from_gserialized(), lwgeom_is_empty(), PG_FUNCTION_INFO_V1(), POINTTYPE, and s.

Referenced by geography_project().

{
        LWGEOM *lwgeom1 = NULL;
        LWGEOM *lwgeom2 = NULL;
        GSERIALIZED *g1 = NULL;
        GSERIALIZED *g2 = NULL;
        double azimuth;
        SPHEROID s;
        uint32_t type1, type2;

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

        /* Only return for points. */
        type1 = gserialized_get_type(g1);
        type2 = gserialized_get_type(g2);
        if ( type1 != POINTTYPE || type2 != POINTTYPE )
        {
                elog(ERROR, "ST_Azimuth(geography, geography) is only valid for point inputs");
                PG_RETURN_NULL();
        }

        lwgeom1 = lwgeom_from_gserialized(g1);
        lwgeom2 = lwgeom_from_gserialized(g2);

        /* EMPTY things cannot be used */
        if ( lwgeom_is_empty(lwgeom1) || lwgeom_is_empty(lwgeom2) )
        {
                lwgeom_free(lwgeom1);
                lwgeom_free(lwgeom2);
                elog(ERROR, "ST_Azimuth(geography, geography) cannot work with empty points");
                PG_RETURN_NULL();
        }

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

        /* Calculate the direction */
        azimuth = lwgeom_azumith_spheroid(lwgeom_as_lwpoint(lwgeom1), lwgeom_as_lwpoint(lwgeom2), &s);

        /* Clean up */
        lwgeom_free(lwgeom1);
        lwgeom_free(lwgeom2);

        PG_FREE_IF_COPY(g1, 0);
        PG_FREE_IF_COPY(g2, 1);

        /* Return NULL for unknown (same point) azimuth */
        if( isnan(azimuth) )
        {
                PG_RETURN_NULL();
        }

        PG_RETURN_FLOAT8(azimuth);
}

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