Added Transformable class to simplify collision calculation

src/Transformable.hs

@@ -0,0 +1,37 @@
+{-# LANGUAGE TypeOperators, TypeSynonymInstances #-}
+
+module Transformable ( Coord
+                     , Vector3
+                     , Transform
+                     , Transformable(..)
+                     , translate
+                     , rotate
+                     , scale
+                     ) where
+
+import Data.LinearMap
+
+type Coord = Double
+
+type Vector3 = (Coord, Coord, Coord)
+type Transform = Vector3 :-* Vector3
+
+class Transformable a where
+  (><) :: Transform -> a -> a
+
+instance Transformable Transform where
+  t1 >< t2 = t1 *.* t2
+
+instance Transformable Vector3 where
+  t >< v = t `lapply` v
+
+translate :: Coord -> Coord -> Transform
+translate dx dy = linear $ \(x, y, w) -> (x + w*dx, y + w*dy, w)
+
+rotate :: Coord -> Transform
+rotate a = linear $ \(x, y, w) -> (c*x - s*y, s*x + c*y, w) where
+  c = cos a
+  s = sin a
+
+scale :: Coord -> Transform
+scale s = linear $ \(x, y, w) -> (s*y, s*y, w)