open Graphics;;
open Printf;;
open Unix;;

open_graph " 640x480";;



let colorR = function
  0 -> yellow
  | 1 -> red
  | 2 -> green
  | 3 -> blue
  | x -> black;;

while true do
  for j = 255 downto 1 do
    for i = 12 downto 1 do

    let radius = i * 20 in
    eprintf "radius is %d\n" radius;

    (* set_color (rgb j (((j + 255/3) mod 255)) (((j + 255*2/3) mod 255)) ); *)
    set_color (rgb ( j/i mod 255) (255 mod j/i) (j/i));
    fill_circle 320 240 radius

    done;
    Unix.sleepf 0.4
  done

done;

read_line ();;