Added glass material

app/Main.hs

@@ -35,6 +35,20 @@ scatter (Ray o d) (Hit t p n (Lambertian c)) = do
 scatter (Ray o d) (Hit t p n (Metal c)) = do
   let reflected = reflect (unitVector d) n
   return $ Ray p reflected
+scatter (Ray o d) (Hit t p n (Glass c)) = do
+  let refraction_ratio = if isFrontFace (Ray o d) n then 1.0 / 1.5 else 1.0
+  let ud = unitVector d
+  let ct = min (ud `dotP` (unitVector n)) 1.0
+  let st = sqrt (1.0 - ct * ct)
+  rVal <- rand
+
+  if refraction_ratio * st > 1.0 || reflectance ct refraction_ratio < rVal
+    then do
+      let reflected = reflect ud n
+      return $ Ray p reflected
+    else do
+      let refracted = refract ud n refraction_ratio
+      return $ Ray p refracted
 
 getRayColor :: (Shape s, RandomGen g) => [s] -> Int -> Ray Double -> Rand g (V3 Double)
 getRayColor ws d r = do
@@ -105,8 +119,9 @@ main = do
   let w = 400
   let h = 400
   let world =
-        [ Circle (V3 0.0 0.0 (-1.0)) 0.25 (Metal (V3 0.8 0.8 0.8)),
-          Circle (V3 0.0 (-10.25) (-1.0)) 10 (Lambertian (V3 0.7 0.3 0.3))
+        [ Circle (V3 (0.0) 0.0 (-1.0)) 0.25 (Glass (V3 1.0 1.0 1.0)),
+          Circle (V3 (-0.5) 0.0 (-1.0)) 0.25 (Lambertian (V3 0.7 0.1 0.1)),
+          Circle (V3 0.0 (-10.25) (-1.0)) 10 (Lambertian (V3 0.7 0.6 0.5))
         ]
   let coords = reverse $ range ((-1 * (w `div` 2), -1 * (h `div` 2)), ((w `div` 2) - 1, (h `div` 2) - 1)) -- "canvas"
   colors <- mapM (\x -> rayTrace x (w, h) (1.0, 1.0) world) coords