Add more wall reflection/randomisation

src/Geometry.hs

@@ -139,6 +139,20 @@ difference x y
 reflectIn :: Point2 -> Point2 -> Point2
 reflectIn line vec = rotateV (2 * angleBetween line vec) vec
 
+-- takes an angle of entry (measured from x axis) and two wall points and gives a
+-- reflected angle (from x axis)
+reflectAngle :: Float -> Point2 -> Point2 -> Float
+reflectAngle a x y = 2 * argV (x - y) - a
+
+{- | Find the representation (by applying +-pi) of an angle 
+ - that is nearest to another given angle -}
+nearestAngleRep :: Float -> Float -> Float
+nearestAngleRep a b
+    | b >= a && b - a <= pi = b
+    | b >= a = nearestAngleRep a (b - 2*pi)
+    | a - b <= pi = b
+    | otherwise = nearestAngleRep a (b + 2*pi)
+
 {- | Find angle between two points.
  Not normalised, ranges from -2*pi to 2*pi.
 -}