module Main where

import IO
import Monad
import Random
import Pancito

data Block = Outside | Distance Double

frac :: Double -> Double
frac z = abs (z - (fromIntegral (round z)))

testBlock :: Point -> Block
testBlock (x, y) =
    if mx > d then Outside else Distance (1 - mx / d)
  where
    d = 0.45
    x' = frac x
    y' = frac y
    mx = max x' y'

shadeBlock :: Double -> Block -> Colour
shadeBlock t Outside      = interp t grey yellow
shadeBlock t (Distance d) = interp (t * d) black red

middleness :: Point -> Double
middleness p = 0.05 * sin (20 * t) + 1 - min 1 (d / 10.0)
  where 
    (d, t) = toPolar p

temperature :: Point -> Double
temperature p = middleness p

blocks :: Image
blocks p =
    shadeBlock t (testBlock p)
  where
    t = temperature p

clip :: Window -> Filter
clip w im p = if contains w p then im p else transparent

sag :: Transform
sag (x, y) = (x * fx, y + dy)
  where
    m = middleness (x, y)
    dy = 2 * m
    fx = 1 - sin ((pi / 2) * (m / 7))

frame :: Window
frame = ((-10.5,-7),(10.5,1))

clipFrame :: Window
clipFrame = ((-9.55,-6.55),(9.55,4.55))

main = writePpmAlias 3 "blocks.ppm" 8 white (300, 120) ((-10.5,-7.5),(10.5,5)) (clip clipFrame blocks . sag)