Continue streaming refactor

src/Dodge/Base/Collide.hs

@@ -18,6 +18,7 @@ module Dodge.Base.Collide
     , wallsOnCirc
     , wallsOnCirc'
     , wallsOnLineHit
+    , collideCircWallsStream
     , collideCircWalls
     , collideCircWallsList
 --    , collideCircWalls'
@@ -320,6 +321,21 @@ overlapCircWalls p r = S.mapMaybe dointersect
     dointersect wl = f (_wlLine wl) <&> (,wl)
     f (a,b) = intersectSegSeg p (p -.- r *.* vNormal (normalizeV (a -.- b))) a b
 
+collideCircWallsStream :: Point2 -> Point2 -> Float -> Stream (Of Wall) Identity ()
+    -> (Point2, Maybe Wall)
+collideCircWallsStream sp ep rad = runIdentity
+    . S.fold_ findPoint (ep, Nothing) id
+  where
+    findPoint (p,mwl) wl = maybe (p,mwl) (,Just wl) . uncurry (intersectSegSeg sp p) 
+        . shiftbyrad
+        . _wlLine $ wl
+    shiftbyrad (a,b) = bimap f f
+        (a +.+ rad *.* normalizeV (a -.-b)
+        ,b +.+ rad *.* normalizeV (b -.-a)
+        )
+      where
+        f = ((rad *.* normalizeV (vNormal $ a -.- b)) +.+)
+
 overlapCircWallsClosest :: Point2 -> Float -> Stream (Of Wall) Identity () -> Maybe (Point2,Wall)
 overlapCircWallsClosest p r = runIdentity
     . L.purely S.fold_ (L.minimumBy (compare `on` (dist p . fst)))