import Ring 
import PointsForRendering
import StateUtil

import Graphics.Rendering.OpenGL
import Data.IORef
import Graphics.UI.GLUT  as GLUT

_STEP = 0.001

main = do
  (progName,_) <-  getArgsAndInitialize
  initialDisplayMode $= [DoubleBuffered]
  createWindow progName
  radius <- new 0.1
  step   <- new _STEP
  displayCallback $= display radius
  idleCallback $= Just (idle radius step)
  mainLoop

display radius = do
  clear [ColorBuffer]
  r <- get radius
  ring r (r+0.2)
  swapBuffers

idle radius step = do 
  r <- get radius
  s <- get step
  if r>=1 then step $= (-_STEP) 
          else if r<=0 then step $= _STEP
                       else return ()
  s <- get step
  radius $= r+s
  postRedisplay Nothing