root/branches/debug/extra/driving_distance/sql/routing_dd_wrappers.sql

--
-- Copyright (c) 2005 Sylvain Pasche,
--               2006-2007 Anton A. Patrushev, Orkney, Inc.
--
-- This program is free software; you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation; either version 2 of the License, or
-- (at your option) any later version.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with this program; if not, write to the Free Software
-- Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.


-- BEGIN;
----------------------------------------------------------
-- Draws an alpha shape around given set of points.
--
-- Last changes: 14.02.2008
----------------------------------------------------------
CREATE OR REPLACE FUNCTION points_as_polygon(query varchar)
       RETURNS SETOF GEOMS AS
$$
DECLARE
     r record;
     path_result record;                                             
     i int;                                                          
     q text;
     x float8[];
     y float8[];
     geom geoms;
     id integer;
BEGIN
        
     id :=0;
                                                                             
     i := 1;                                                                 
     q := 'select 1 as gid, GeometryFromText(''POLYGON((';
     
     FOR path_result IN EXECUTE 'select x, y from alphashape('''|| 
         query || ''')' LOOP
         x[i] = path_result.x;
         y[i] = path_result.y;
         i := i+1;
     END LOOP;

     q := q || x[1] || ' ' || y[1];
     i := 2;

     WHILE x[i] IS NOT NULL LOOP
         q := q || ', ' || x[i] || ' ' || y[i];
         i := i + 1;
     END LOOP;

    q := q || ', ' || x[1] || ' ' || y[1];
    q := q || '))'',-1) as the_geom';

    FOR r in EXECUTE q LOOP
         geom.gid=r.gid;
         geom.the_geom=r.the_geom;
         id := id+1;
         geom.id       := id;
         RETURN NEXT geom;
    END LOOP;

    RETURN;
END;
$$

LANGUAGE 'plpgsql' VOLATILE STRICT;

-- COMMIT;