41 lines
1.2 KiB
Haskell
41 lines
1.2 KiB
Haskell
import System.Random (StdGen, mkStdGen, randomR)
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type Point = (Float, Float)
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transformation1 :: Point -> Point
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transformation1 (_, y) = (0, 0.16 * y)
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transformation2 :: Point -> Point
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transformation2 (x, y) = (0.85 * x + 0.04 * y, -0.04 * x + 0.85 * y + 1.6)
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transformation3 :: Point -> Point
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transformation3 (x, y) = (0.2 * x - 0.26 * y, 0.23 * x + 0.22 * y + 1.6)
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transformation4 :: Point -> Point
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transformation4 (x, y) = (-0.15 * x + 0.28 * y, 0.26 * x + 0.24 * y + 0.44)
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applyTransformation :: Point -> Float -> Point
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applyTransformation point random
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| random < 0.01 = transformation1 point
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| random < 0.86 = transformation2 point
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| random < 0.93 = transformation3 point
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| otherwise = transformation4 point
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genNextPoint :: StdGen -> Point -> (Point, StdGen)
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genNextPoint gen point =
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let (random, newGen) = randomR (0.0, 1.0 :: Float) gen
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in (applyTransformation point random, newGen)
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barnsleyFern :: StdGen -> Point -> Int -> [Point]
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barnsleyFern _ _ 0 = []
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barnsleyFern gen startPoint n =
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let (nextPoint, newGen) = genNextPoint gen startPoint
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in startPoint : barnsleyFern newGen nextPoint (n - 1)
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n = 1000
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randomSeed = 17
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main :: IO ()
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main = print $ barnsleyFern (mkStdGen randomSeed) (0, 0) n
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