Improve dual lasers

src/Dodge/Update.hs

@@ -23,6 +23,7 @@ import Data.Maybe
 --import Data.Function
 import qualified Data.IntMap.Strict as IM
 import qualified Data.Map.Strict as M
+import Control.Applicative
 --import qualified Data.Set as S
 --import Data.Monoid
 --import System.Random
@@ -170,15 +171,16 @@ intersectBeamBeams :: Beam -> [Beam]
 intersectBeamBeams bm bms = f [] $ _bmPoints bm
   where
     f ps (x:y:ys) = case intersectSegBeams x y bms of
-        Just (z,a) -> ((z:x:ps), Just (z,(x,y,bm),a))
+        Just (z,a) -> (z:x:ps, Just (z,(x,y,bm),a))
         Nothing -> f (x:ps) (y:ys)
-    f ps (x:[]) = (x:ps, Nothing)
+    f ps [x] = (x:ps, Nothing)
     f _ _ = error "made an empty beam"
 
 intersectSegBeams :: Point2 -> Point2 -> [Beam] -> Maybe (Point2,(Point2,Point2,Beam))
 intersectSegBeams sp ep (bm:bms) = case intersectSegBeam sp ep bm of
     Nothing -> intersectSegBeams sp ep bms
-    Just a@(z,_) -> maybe (Just a) Just $ intersectSegBeams sp z bms
+    --Just a@(z,_) -> maybe (Just a) Just $ intersectSegBeams sp z bms
+    Just a@(z,_) -> intersectSegBeams sp z bms <|> Just a
 intersectSegBeams _ _ _ = Nothing
 
 intersectSegBeam :: Point2 -> Point2 -> Beam -> Maybe (Point2,(Point2,Point2,Beam))
@@ -188,7 +190,8 @@ intersectSegBeam sp ep bm = case intersectSegSegs' sp ep (_bmPoints bm) of
 
 intersectSegSegs' :: Point2 -> Point2 -> [Point2] -> Maybe (Point2,Point2,Point2)
 intersectSegSegs' sp ep (x:y:ys) = case intersectSegSeg sp ep x y of
-    Just z  -> maybe (Just (z,x,y)) Just $ intersectSegSegs' sp z (y:ys)
+    --Just z  -> maybe (Just (z,x,y)) Just $ intersectSegSegs' sp z (y:ys)
+    Just z  -> intersectSegSegs' sp z (y:ys) <|> Just (z,x,y)
     Nothing -> intersectSegSegs' sp ep (y:ys)
 intersectSegSegs' _ _ _ = Nothing