[postgis-users] Create LINESTRING with a LOOP

[paallen at attglobal.net]

Hi all,

I am writing a function that returns a linestring
(4D).  I am creating this linestring within a
loop.  But it doesn't work because the first two
times through the linestring is null or empty.

What is the most efficent way to create a
linestring within a LOOP?

Below is a simplified example of what I am trying
to do.

thanks,

Phillip Allen

CREATE OR REPLACE FUNCTION mc_test2( )
	RETURNS geometry AS
$BODY$
	DECLARE
		gline geometry;
		gpt geometry;
		x integer;
		str text;
	BEGIN
	x := 1;
	gline := LINESTRING(EMPTY);
		WHILE (x <= 5) LOOP
			str := $$SRID=32717;POINT($$ || 400000 + x ||
$$ $$ || 900000 + x || $$ $$ || 3500 + x || $$ $$
|| x || $$)$$;
			gline := AddPoint(gline, GeomFromEWKT(str));
			x := x+1;

		END LOOP;
		RETURN gline;
	END;
$BODY$
  LANGUAGE 'plpgsql' VOLATILE;