From 85a6ddf10914c5798db5044b604aae31551fe780 Mon Sep 17 00:00:00 2001
From: Yann Herklotz <ymherklotz@gmail.com>
Date: Wed, 30 Jan 2019 22:27:59 +0000
Subject: Added reflections

---
 src/Main.hs |  3 +++
 src/Vec.hs  | 11 ++++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/Main.hs b/src/Main.hs
index b92807c..b674eb6 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -52,3 +52,6 @@ main = do
   let i = circleImage (normalise 511) 511
   BL.writeFile "normal.ppm" . encodePPM . clampImage $ i
   BL.writeFile "normal.pfm" . encode . revColour $ i
+  let r = circleImage (reflect 511 (Vec (0, 0, 1))) 511
+  BL.writeFile "reflect.ppm" . encodePPM . clampImage $ r
+  BL.writeFile "reflect.pfm" . encode . revColour $ r
diff --git a/src/Vec.hs b/src/Vec.hs
index 19a8485..9e4fdbd 100644
--- a/src/Vec.hs
+++ b/src/Vec.hs
@@ -18,6 +18,14 @@ newtype Vec a = Vec { unVec :: (a, a, a) }
 instance Functor Vec where
   fmap f (Vec (a, b, c)) = Vec (f a, f b, f c)
 
+instance (Num a) => Num (Vec a) where
+  (Vec (x1, y1, z1)) + (Vec (x2, y2, z2)) = Vec (x1 + x2, y1 + y2, z1 + z2)
+  (Vec (x1, y1, z1)) - (Vec (x2, y2, z2)) = Vec (x1 - x2, y1 - y2, z1 - z2)
+  (Vec (x1, y1, z1)) * (Vec (x2, y2, z2)) = Vec (x1 * x2, y1 * y2, z1 * z2)
+  abs = fmap abs
+  signum = fmap signum
+  fromInteger i = Vec (fromInteger i, 0, 0)
+
 findZ :: (Floating a) => a -> a -> Vec a
 findZ x y =
   Vec (x, y, sqrt (1 - x^^2 - y^^2))
@@ -34,6 +42,7 @@ normalise size (y, x) =
 
 reflect :: (Floating a) => Int -> Vec a -> (Int, Int) -> Vec a
 reflect size v (y, x) =
-  n
+  l - v
   where
     n = normalise size (y, x)
+    l = ((2 * dot n v)*) <$> n
-- 
cgit