23 lines
754 B
Haskell
23 lines
754 B
Haskell
import Data.List (genericLength)
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shades = ".:!*oe%#&@"
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n = genericLength shades
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dot a b = sum $ zipWith (*) a b
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normalize x = (/ sqrt (x `dot` x)) <$> x
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deathStar r k amb = unlines $
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[ [ if x*x + y*y <= r*r
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then let vec = normalize $ normal x y
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b = (light `dot` vec) ** k + amb
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intensity = (1 - b)*(n - 1)
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in shades !! round ((0 `max` intensity) `min` n)
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else ' '
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| y <- map (/2.12) [- 2*r - 0.5 .. 2*r + 0.5] ]
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| x <- [ - r - 0.5 .. r + 0.5] ]
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where
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light = normalize [-30,-30,-50]
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normal x y
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| (x+r)**2 + (y+r)**2 <= r**2 = [x+r, y+r, sph2 x y]
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| otherwise = [x, y, sph1 x y]
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sph1 x y = sqrt (r*r - x*x - y*y)
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sph2 x y = r - sqrt (r*r - (x+r)**2 - (y+r)**2)
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