From 40860a46fa0a22cc376b015e36744c8573f92654 Mon Sep 17 00:00:00 2001
From: "Matthias P. Braendli" <matthias.braendli@mpb.li>
Date: Mon, 2 Dec 2013 22:51:42 +0100
Subject: sphere intersection recursion

---
 raytracer.hs | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/raytracer.hs b/raytracer.hs
index 40ff6aa..a49e5cd 100644
--- a/raytracer.hs
+++ b/raytracer.hs
@@ -38,7 +38,7 @@ spheres num = [ trace ("Sphere at " ++
                     show (round (80 * sin(num * degrees))) ++ "," ++
                     show (round (80 * cos(num * degrees))) ++ ",5" )
             Sphere (80 * sin(num * degrees), 80 * cos(num * degrees), 5) 10 (255,60,0),
-            sphere1, sphere2]
+            sphere1]
 
 writenum :: Double -> IO ()
 writenum num = trace ("Rendering " ++ show (filename $ round num))
@@ -55,10 +55,10 @@ beta2 = 120 * degrees
 
 floorscale = 4
 
-w = 400
-h = 220
+w = 600 * 2
+h = 330 * 2
 
-oversampling = 1 -- each pixel is oversampling^2 rays
+oversampling = 2 -- each pixel is oversampling^2 rays
 
 black :: Color
 black = (0,0,0)
@@ -74,6 +74,10 @@ imgheader = "P3 " ++ (show $ round w) ++ " " ++ (show $ round h) ++ " 255\n"
 alphas = take (round w) [alpha1,(alpha1 + ((alpha2 - alpha1) / (w-1)))..]
 betas  = take (round h) [beta1,(beta1 + ((beta2 - beta1) / (h-1)))..]
 
+attenuate_color :: Double -> Color -> Color
+attenuate_color factor (r,g,b)  = ( round $ fromIntegral r * factor,
+                                    round $ fromIntegral g * factor,
+                                    round $ fromIntegral b * factor)
 
 -- spherical projection,
 -- return coordinates from a given coordinate, extended by given
@@ -99,9 +103,12 @@ discr source (alpha, beta) (Sphere centre radius _) = 4*(( aa * u + bb * v + cc
 
 -- the intersect functions return (Coord, Distance, Color)
 -- distance = 0 means no intersection
-intersect_sphere :: Coord -> ScreenCoord -> Sphere -> (Coord, Double, Color)
-intersect_sphere source (alpha, beta) (Sphere centre radius color)
-        | delta > 0 = (spherical_proj source alpha beta t, t, color)
+intersect_sphere :: Coord -> [Sphere] -> ScreenCoord -> Sphere -> (Coord, Double, Color)
+intersect_sphere source spheres (alpha, beta) (Sphere centre radius color)
+        | delta > 0 =   (spherical_proj source alpha beta t, t,
+                         attenuate_color 0.5 $
+                         pixel_color (spherical_proj source alpha beta t) spheres reflection_angle
+                        )
         | otherwise = ((0,0,0), 0, black)
             where   t = min ((-b - sqrt(delta)) / (2*a)) ((-b + sqrt(delta)) / (2*a))
                     delta = discr source (alpha, beta) (Sphere centre radius color)
@@ -113,6 +120,7 @@ intersect_sphere source (alpha, beta) (Sphere centre radius color)
                     aa = sin beta * cos alpha
                     bb = sin beta * sin alpha
                     cc = cos beta
+                    reflection_angle = (0, -beta)
 
 
 intersect_point_floor :: Coord -> ScreenCoord -> (Coord, Double)
@@ -159,7 +167,7 @@ instance Ord SphereIntersect where
 nearest_sphere :: Coord -> ScreenCoord -> [Sphere] -> SphereIntersect
 nearest_sphere source scoord spheres =
                         minimum [(SphereIntersect distance color) | (_, distance, color) <- intersections]
-                        where intersections = map (intersect_sphere source scoord) spheres
+                        where intersections = map (intersect_sphere source spheres scoord) spheres
 
 -- also include floor in objects
 nearest_obj :: Coord -> ScreenCoord -> [Sphere] -> (Double, Color)
-- 
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