1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
|
import System.IO
import Data.Char
-- ppm image file
-- P3 width height maxcolorval r g b r g b r g b ...
-- max line length: 70
degrees = pi / 180
eye = [0, 0, 2]
alpha1 = 80 * degrees
alpha2 = -40 * degrees
beta1 = 15 * degrees
beta2 = -30 * degrees
w = 1000
h = 500
oversampling = 2 -- each pixel is 2x2 rays
ov_alphaoffset = ((alpha2 - alpha1) / (w-1)) / oversampling
ov_betaoffset = ((beta2 - beta1) / (h-1)) / oversampling
ov_alphaoffsets = take oversampling [0,ov_alphaoffset..]
ov_betaoffsets = take oversampling [0,ov_betaoffset..]
imgheader = "P3 " ++ (show w) ++ " " ++ (show h) ++ " 255\n"
alphas = take (round w) [alpha1,(alpha1 + ((alpha2 - alpha1) / (w-1)))..]
betas = take (round h) [beta1,(beta1 + ((beta2 - beta1) / (h-1)))..]
-- intersect at (x , y , depth )
intersect_floor :: Double -> Double -> (Double, Double, Double)
intersect_floor alpha beta
| beta < 0 = (-2 * (cos alpha) / (sin beta) - 2 * (cos beta) / (sin beta),
-2 * (sin alpha) / (sin beta),
-2 / (sin beta) )
| otherwise = (0, 0, 0)
floorcolor :: Double -> Double -> (Int, Int, Int)
floorcolor alpha beta
| (round (x/8) `mod` 2) == (round (y/8) `mod` 2) = (attn, 0, 0)
| otherwise = (attn, attn, attn)
where attn = max 0 (round (255 - 8*(sqrt t)))
(x, y, t) = intersect_floor alpha beta
-- blue is beautiful
skycolor :: Double -> Double -> (Int, Int, Int)
skycolor alpha beta = (60,
round ((sqrt (alpha/6)) / (sqrt (90 * degrees)) * 128),
round ((sqrt beta) / (sqrt (90 * degrees)) * 255) )
pixel_color :: Double -> Double -> (Int, Int, Int)
pixel_color alpha beta
| beta > 0 = skycolor alpha beta
| beta == 0 = (0, 255, 0)
| otherwise = floorcolor alpha beta
cartProdTranspose xs ys = [(y,x) | x <- xs, y <- ys]
cartProd xs ys = [(x,y) | x <- xs, y <- ys]
pixel_to_ppm (r,g,b) = show r ++ " " ++ show g ++ " " ++ show b ++ "\n"
--tuplesum x y = (a1 + a2, b1 + b2)
-- where (a1, a2) = x
-- (b1, b2) = y
-- from one pixel alpha beta, get a list of oversampled pixels
--oversample (a,b) = (cartProd ov_alphaoffsets ov_betaoffsets)
-- allpixels = map (uncurry pixel_color) (cartProdTranspose betas alphas)
--image = imgheader ++ (foldr (++) "" (map pixel_to_ppm allpixels))
--main = writeFile "foo.ppm" image
|
