module Bouncy where

import GraphicsUtils 

data Ball = Ball { p :: Point,
                   v :: Point }  

drawBall :: Ball-> Graphic
drawBall (Ball {p= (x, y)}) =
  withColor Red (ellipse (x- 10, y-10) (x+10, y+10))

move :: Ball-> Ball 
move (Ball {p= (px, py), v= (vx, vy)})=   
  Ball {p= (px', py'), v= (vx, vy')} where
    px' = (px+ vx) `mod` 500
    py0 = py+ vy
    py' = if py0> 500 then 500-(py0-500) else py0 
    vy' = (if py0> 500 then -vy else vy)+ 1

main :: IO ()
main = runGraphics $
  do w<- openWindowEx "Bounce!" Nothing (500, 500) 
                       DoubleBuffered (Just 30)
     loop w (Ball{p=(0, 10), v= (5, 0)}) where 
       loop :: Window-> Ball-> IO ()
       loop w b = 
         do setGraphic w (drawBall b)
            getWindowTick w          
            loop w (move b)