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118 lines
3.9 KiB
118 lines
3.9 KiB
module Main where
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import Control.Monad (mapM)
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import Control.Monad.Random
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import Data.Ix
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import Data.Maybe
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import Hittable
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import IOUtils
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import Linear.V2
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import Linear.V3
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import Linear.Vector
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import Material
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import Maths
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import Ray
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type Coord = (Int, Int)
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type ImageDimensions = (Int, Int)
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type ViewPortDimensions = (Double, Double)
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-- TODO
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-- antialiasing
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-- scatter rays based on the material of the object that was hit
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scatter :: (RandomGen g) => Ray -> Hit -> Rand g (Ray)
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scatter (Ray o d) (Hit t p n (Lambertian c)) = do
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r <- randV3
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let target = p ^+^ colorWithNormal (unitVector n) ^+^ r
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return $ Ray p (target ^-^ p)
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scatter (Ray o d) (Hit t p n (Metal c)) = do
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let reflected = reflect (unitVector d) n
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return $ Ray p reflected
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scatter (Ray o d) (Hit t p n (Glass c)) = do
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let refraction_ratio = if isFrontFace (Ray o d) n then 1.0 / 1.5 else 1.0
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let ud = unitVector d
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let ct = min (ud `dotP` (unitVector n)) 1.0
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let st = sqrt (1.0 - ct * ct)
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rVal <- rand
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if refraction_ratio * st > 1.0 || reflectance ct refraction_ratio < rVal
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then do
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let reflected = reflect ud n
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return $ Ray p reflected
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else do
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let refracted = refract ud n refraction_ratio
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return $ Ray p refracted
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getRayColor :: (Shape s, RandomGen g) => [s] -> Int -> Ray -> Rand g (V3 Double)
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getRayColor ws d r = do
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let h = getBestHit (mapMaybe (testHit r) ws)
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v <- getRayColor' r h ws d
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return v
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-- get color of pixel according to the closest hit found
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getRayColor' :: (Shape s, RandomGen g) => Ray -> Maybe Hit -> [s] -> Int -> Rand g (V3 Double)
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getRayColor' (Ray o d) Nothing _ _ = do return $ colorGradient (unitVector d)
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getRayColor' (Ray o d) _ _ 0 = do return $ colorGradient (unitVector d)
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getRayColor' (Ray o d) (Just (Hit t p n m)) ws depth = do
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let a = attenuation m
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ray <- scatter (Ray o d) (Hit t p n m)
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nextVal <- getRayColor ws (depth - 1) ray
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return (a * nextVal)
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-- used for coloring the background, color based on direction vector
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colorGradient :: V3 Double -> V3 Double
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colorGradient (V3 x y z) = do
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let t = 0.5 * (y + 1.0)
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(1.0 - t) *^ V3 1.0 1.0 1.0 + t *^ V3 0.5 0.7 1.0
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-- from a list of possible hits, get the closest possible hit found
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getBestHit :: [Hit] -> Maybe Hit
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getBestHit [] = Nothing
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getBestHit (h : hs) = Just (getBestHit' hs h)
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getBestHit' :: [Hit] -> Hit -> Hit
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getBestHit' (h : hs) bestHit =
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if root h < root bestHit
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then getBestHit' hs h
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else getBestHit' hs bestHit
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getBestHit' [] hit = hit
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colorWithNormal :: V3 Double -> V3 Double
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colorWithNormal v = 0.5 *^ (v ^+^ V3 1.0 1.0 1.0)
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-- heart of loop, for each x y coordinate pixel, convert it into world space and then run the ray tracing algorithm
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-- run [samples] times in order to increase fidelity
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rayTrace :: (Shape s) => (Int, Int) -> ImageDimensions -> ViewPortDimensions -> [s] -> Int -> IO (V3 Double)
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rayTrace (x, y) (w, h) (vw, vh) world samples = do
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let maxDepth = 50
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l <- replicateM samples (evalRandIO (getRayColor world maxDepth $ buildRay (xf * (vw / wf)) (yf * (vh / hf))))
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return $ foldl (^+^) (V3 0.0 0.0 0.0) l
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where
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xf = fromIntegral x
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yf = fromIntegral y
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wf = fromIntegral (w - 1)
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hf = fromIntegral (h - 1)
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main :: IO ()
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main = do
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let w = 400
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let h = 400
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let samples = 25
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let world =
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[ Circle (V3 (0.0) 0.0 (-1.0)) 0.25 (Glass (V3 1.0 1.0 1.0)),
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Circle (V3 (-0.5) 0.0 (-1.0)) 0.25 (Lambertian (V3 0.7 0.1 0.1)),
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Circle (V3 0.0 (-10.25) (-1.0)) 10 (Lambertian (V3 0.7 0.6 0.5))
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]
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let coords = reverse $ range ((-1 * (w `div` 2), -1 * (h `div` 2)), ((w `div` 2) - 1, (h `div` 2) - 1)) -- "canvas"
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colors <- mapM (\x -> rayTrace x (w, h) (1.0, 1.0) world samples) coords
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let convertedColors = map v3ToColor colors
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-- print ppm header
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putStrLn "P3"
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putStrLn (show w ++ " " ++ show h)
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putStrLn "255"
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-- print each color converted to ppm format string
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mapM_ (colorToString samples) convertedColors
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mapM_ print convertedColors
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