矩形拉长

CREATE OR REPLACE FUNCTION "public"."mbk_st_iphone20"("geom" "public"."geometry")
  RETURNS "public"."geometry" AS $BODY$
DECLARE
    temp geometry;
		pCount int;
		startIndex int;
		latDiff float8;
		lonDiff float8;
		newPoints geometry[9];
		
    result geometry;
begin
    if $1 is not null
    then
				temp := $1;
				FOR i IN 1..40 LOOP
						pCount := ST_NPoints(temp);
						IF pCount <= 5 OR pCount > 50 THEN
								EXIT;
						END IF;
						temp := st_simplify(temp,0.0000025 * i);
				END LOOP;
				pCount := ST_NPoints(temp);
				if pCount = 5
				then
						BEGIN
								temp := ST_Boundary(temp);
								if st_length(st_makeline(ST_PointN(temp,1), ST_PointN(temp,2))) > st_length(st_makeline(ST_PointN(temp,2), ST_PointN(temp,3)))
								then startIndex := 2;
								else startIndex := 1;
								end if;
								latDiff := ((ST_Y(ST_PointN(temp,startIndex))-ST_Y(ST_PointN(temp,startIndex+3))) + (ST_Y(ST_PointN(temp,startIndex+1))-ST_Y(ST_PointN(temp,startIndex+2))))/2;
								lonDiff := ((ST_X(ST_PointN(temp,startIndex+3))-ST_X(ST_PointN(temp,startIndex))) + (ST_X(ST_PointN(temp,startIndex+2))-ST_X(ST_PointN(temp,startIndex+1))))/2;
			
								latDiff := latDiff * 50;
								lonDiff := lonDiff * 50;
								newPoints[0] := st_setsrid(ST_PointN(temp,startIndex),4326);
								newPoints[1] := st_setsrid(st_point(ST_X(ST_PointN(temp,startIndex)) - lonDiff, ST_Y(ST_PointN(temp,startIndex)) + latDiff),4326);
								newPoints[2] := st_setsrid(st_point(ST_X(ST_PointN(temp,startIndex+1)) - lonDiff, ST_Y(ST_PointN(temp,startIndex+1)) + latDiff),4326);
								newPoints[3] := st_setsrid(ST_PointN(temp,startIndex+1),4326);
								newPoints[4] := st_setsrid(ST_PointN(temp,startIndex+2),4326);
								newPoints[5] := st_setsrid(st_point(ST_X(ST_PointN(temp,startIndex+2)) + lonDiff, ST_Y(ST_PointN(temp,startIndex+2)) - latDiff),4326);
								newPoints[6] := st_setsrid(st_point(ST_X(ST_PointN(temp,startIndex+3)) + lonDiff, ST_Y(ST_PointN(temp,startIndex+3)) - latDiff),4326);
								newPoints[7] := st_setsrid(ST_PointN(temp,startIndex+3),4326);
								newPoints[8] := newPoints[0];
								
								result := st_setsrid(st_makepolygon(st_makeline(newPoints)),4326);
								if not ST_IsValid(result)
								then result := null;
								end IF;
						EXCEPTION
								WHEN others THEN
								raise notice '%', ST_PointN(temp,startIndex);
						END;
				end if;
    end if;
    return result;
end
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100