AI refactor

src/Geometry/Vector.hs

@@ -87,10 +87,18 @@ Always positive.
  -}
 angleVV :: Point2 -> Point2 -> Float
 {-# INLINE angleVV #-}
-angleVV a b = let ma = magV a
-                  mb = magV b
-                  d  = a `dotV` b
-              in  acos $ d / (ma * mb)
+angleVV a b = 
+    let ma = magV a
+        mb = magV b
+        d  = a `dotV` b
+    in  acos $ d / (ma * mb)
+
+{- | Safe version of 'angleVV' that returns 0 if either vector is null. -}
+safeAngleVV :: Point2 -> Point2 -> Float
+{-# INLINE safeAngleVV #-}
+safeAngleVV a b
+    | a == (0,0) || b == (0,0) = 0
+    | otherwise                = angleVV a b
 
 {- | Dot product.
  -}