gistfile1.hs

trun :: Double -> Double -> GLfloat
trun h i = realToFrac ((i-0.5) * h) :: GLfloat

drawVelocity :: (Grid,Grid) -> IO ()
drawVelocity (u,v) = do
  color3f (Color3 1 1 1)
  lineWidth $= 1.0
  let h = 1.0 / realToFrac n
  let f = trun h
  renderPrimitive Lines $ forM_ [(x,y) | x<-[1..n], y<-[1..n] ]
                     (\(i,j) ->
                          do
                            uV <- readVal u (i,j)
                            vV <- readVal v (i,j)
                            vertex2f (Vertex2 (f (realToFrac i)) (f (realToFrac j)))
                            vertex2f (Vertex2 (f ((realToFrac i) + uV)) (f ((realToFrac j) + vV))))