Allow creatures to path around chasms

src/Dodge/Base/Collide.hs

@@ -37,6 +37,7 @@ module Dodge.Base.Collide (
     collide3,
 ) where
 
+import Data.Monoid
 import Control.Lens
 import Control.Monad
 import qualified Data.IntSet as IS
@@ -326,10 +327,13 @@ hasLOSIndirect p1 p2 =
 
 isWalkable :: Point2 -> Point2 -> World -> Bool
 {-# INLINE isWalkable #-}
-isWalkable p1 p2 =
-    not
+isWalkable p1 p2 w =
+    (not
         . collidePointTestFilter (not . (^?! wlPathable)) p1 p2
-        . wlsNearSeg p1 p2
+        . wlsNearSeg p1 p2 $ w)
+    && not (getAny $ foldMap f (w ^. cWorld . chasms))
+  where
+    f = foldMap (Any . isJust . uncurry (intersectSegSeg p1 p2)) . loopPairs
 
 canSee :: Int -> Int -> World -> Bool
 {-# INLINE canSee #-}