Various tweaks

src/Dodge/Base/Zone.hs

@@ -148,6 +148,22 @@ wallsDoubleScreen w -- = IM.unions [f b $ f a $ _wallsZone w | (a,b) <- is]
     xs = [x - n .. x + n]
     ys = [y - n .. y + n]
 
+wallsOnScreen :: World -> IM.IntMap Wall
+wallsOnScreen w -- = wallsNearZones (zoneOfScreen w) w
+    = foldl' (flip $ IM.union . \i -> innerFold (f i (_wallsZone w))) IM.empty xs
+  where 
+    innerFold m = foldl' (flip $ IM.union . \ j -> f j m) IM.empty ys
+
+    f i m = case IM.lookup i m of 
+        Just val -> val
+        _        -> IM.empty
+    (x,y) = zoneOfPoint $ _cameraCenter w
+    n = ceiling (wh / (_cameraZoom w * zoneSize))
+    wh = max (getWindowX w) (getWindowY w)
+    xs = [x - n .. x + n]
+    ys = [y - n .. y + n]
+
+
 wallsNearZones :: [(Int,Int)] -> World -> IM.IntMap Wall
 wallsNearZones is w -- = IM.unions [f b $ f a $ _wallsZone w | (a,b) <- is]
     = foldl' (flip $ IM.union . \(a,b) -> f b (f a (_wallsZone w))) IM.empty is