geography_project()

Datum geography_project

(

PG_FUNCTION_ARGS

)

Definition at line 979 of file geography_measurement.c.

{
        LWGEOM *lwgeom = NULL;
        LWPOINT *lwp_projected;
        GSERIALIZED *g = NULL;
        GSERIALIZED *g_out = NULL;
        double azimuth = 0.0;
        double distance;
        SPHEROID s;
        uint32_t type;
 
        /* Return NULL on NULL distance or geography */
        if ( PG_NARGS() < 2 || PG_ARGISNULL(0) || PG_ARGISNULL(1) )
                PG_RETURN_NULL();
 
        /* Get our geometry object loaded into memory. */
        g = PG_GETARG_GSERIALIZED_P(0);
 
        /* Only return for points. */
        type = gserialized_get_type(g);
        if ( type != POINTTYPE )
        {
                elog(ERROR, "ST_Project(geography) is only valid for point inputs");
                PG_RETURN_NULL();
        }
 
        distance = PG_GETARG_FLOAT8(1); /* Distance in Meters */
        lwgeom = lwgeom_from_gserialized(g);
 
        /* EMPTY things cannot be projected from */
        if ( lwgeom_is_empty(lwgeom) )
        {
                lwgeom_free(lwgeom);
                elog(ERROR, "ST_Project(geography) cannot project from an empty start point");
                PG_RETURN_NULL();
        }
 
        if ( PG_NARGS() > 2 && ! PG_ARGISNULL(2) )
                azimuth = PG_GETARG_FLOAT8(2); /* Azimuth in Radians */
 
        /* Initialize spheroid */
        spheroid_init_from_srid(fcinfo, gserialized_get_srid(g), &s);
 
        /* Handle the zero distance case */
        if( FP_EQUALS(distance, 0.0) )
        {
                PG_RETURN_POINTER(g);
        }
 
        /* Calculate the length */
        lwp_projected = lwgeom_project_spheroid(lwgeom_as_lwpoint(lwgeom), &s, distance, azimuth);
 
        /* Something went wrong... */
        if ( lwp_projected == NULL )
        {
                elog(ERROR, "lwgeom_project_spheroid returned null");
                PG_RETURN_NULL();
        }
 
        /* Clean up, but not all the way to the point arrays */
        lwgeom_free(lwgeom);
        g_out = geography_serialize(lwpoint_as_lwgeom(lwp_projected));
        lwpoint_free(lwp_projected);
 
        PG_FREE_IF_COPY(g, 0);
        PG_RETURN_POINTER(g_out);
}

References distance(), FP_EQUALS, gserialized_get_srid(), gserialized_get_type(), lwgeom_as_lwpoint(), lwgeom_free(), lwgeom_from_gserialized(), lwgeom_is_empty(), lwgeom_project_spheroid(), lwpoint_as_lwgeom(), lwpoint_free(), POINTTYPE, and s.

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