Fix wall zoning bug

src/Geometry/Zone.hs

@@ -9,15 +9,15 @@ import Data.Foldable
 import qualified Data.IntMap.Strict as IM
 import qualified Data.IntSet as IS
 
-foldl2'
-    :: (b -> a -> a -> b) 
-    -> b 
-    -> [a]
-    -> b
-foldl2' f s (t:ts) = fst $ foldl' g (s, t) ts
-  where
-    g (r,x) y = (f r x y,y)
-foldl2' _ s _ = s
+--foldl2'
+--    :: (b -> a -> a -> b) 
+--    -> b 
+--    -> [a]
+--    -> b
+--foldl2' f s (t:ts) = fst $ foldl' g (s, t) ts
+--  where
+--    g (r,x) y = (f r x y,y)
+--foldl2' _ s _ = s
 
 sortArguments 
     :: Ord a 
@@ -82,6 +82,35 @@ increasingInterval x y
 -- point.
 ddaExt :: Float -> V2 Float -> V2 Float -> IM.IntMap IS.IntSet
 ddaExt s sp@(V2 sx sy) ep@(V2 ex ey) 
+    | x1 <= x2 = addsp . addys . IM.fromDistinctAscList $ zip [x1 .. x2] 
+                    $ map (IS.singleton . divTo s) [x1y,x1y+ydx..]
+    | otherwise = addsp . addys . IM.fromDistinctAscList $ zip [x2-1 .. x1-1]
+                    $ map (IS.singleton . divTo s) [x2y,x2y+ydx..]
+  where
+    addsp im = let V2 x y = sizeZoneOfPoint' s sp
+            in insertXY im (x,y)
+    x1 = divTo s sx
+    x2 = divTo s ex
+    x1y = fx' sp ep $ s * (fromIntegral x1)
+    x2y = fx' sp ep $ s * (fromIntegral x2)
+    ydx = s * ydx' sp ep
+    addys m = add2s m ypairs 
+    y1 = divTo s sy
+    y2 = divTo s ey
+    y1x = fy' sp ep $ s * (fromIntegral y1)
+    y2x = fy' sp ep $ s * (fromIntegral y2)
+    xdy = s * xdy' sp ep
+    ypairs 
+        | y1 <= y2  = zip (map (divTo s) [y1x,y1x+xdy..])
+                         [y1 .. y2] 
+        | otherwise = zip (map (divTo s) [y2x,y2x+xdy..])
+                         [y2-1 .. y1-1] 
+-- | Determines which horizontal and vertical lines on a grid are crossed by a
+-- line. For each adds the x-y index of the square to the right or above the
+-- crossed grid line. Also adds the index of the square containing the start
+-- point.
+ddaExtExt :: Float -> V2 Float -> V2 Float -> IM.IntMap IS.IntSet
+ddaExtExt s sp@(V2 sx sy) ep@(V2 ex ey) 
     | x1 <= x2 = addys . IM.fromDistinctAscList $ zip [x1 .. x2] 
                     $ map (IS.singleton . divTo s) [x1y,x1y+ydx..]
     | otherwise = addys . IM.fromDistinctAscList $ zip [x2-1 .. x1-1]
@@ -137,6 +166,9 @@ add2s imis = foldl'
     (\m (k,x) -> IM.insertWith (\_ old -> IS.insert x old) k (IS.singleton x) m)
     imis
 
+insertXY :: IM.IntMap IS.IntSet -> (Int,Int) -> IM.IntMap IS.IntSet
+insertXY m (k,x) = IM.insertWith (\_ old -> IS.insert x old) k (IS.singleton x) m
+
 addV2s :: IM.IntMap IS.IntSet -> [V2 Int] -> IM.IntMap IS.IntSet
 {-# INLINE addV2s #-}
 addV2s imis = foldl'