Refactor wall points from lists to pairs

src/Dodge/WorldEvent/Flash.hs

@@ -71,7 +71,7 @@ lowLightPic len wdth col (a,b) w = case thingsHit a b w of
         ((p, E3x2 wall):_) 
             -> setCol . lineOfThickness wdth $ [alongSegBy len p wa, alongSegBy len p wb]
                 where x = len *.* normalizeV (wa -.- wb)
-                      (wa:wb:_) = _wlLine wall
+                      (wa,wb) = _wlLine wall
         ((p, E3x1 cr):_) 
             -> setCol . uncurry translate cp . rotate (-0.25 * pi + argV (p -.- cp))
                     $ thickArc 0 (pi/2) (_crRad cr) wdth

src/Dodge/WorldEvent/SpawnParticle.hs

@@ -126,8 +126,7 @@ moveFlame rotd w pt
         , _btVel' = reflV wl
         }
     pOut p = p +.+ safeNormalizeV (sp -.- p)
-    reflV wall = (0.3 *.* reflectIn (_wlLine wall !! 1 -.- _wlLine wall !! 0)
-                            vel )
+    reflV wall = (0.3 *.* reflectIn ((snd $ _wlLine wall) -.- (fst $ _wlLine wall)) vel )
                     +.+
                  (0.2 *.* vel)
     smokeGen = makeFlamerSmokeAt ep

src/Dodge/WorldEvent/ThingsHit.hs

@@ -35,7 +35,7 @@ thingsHit sp ep w
     f i m = case IM.lookup i m of Just val -> val
                                   _        -> IM.empty
     walls = zip (map (fromJust . hitPoint) hitWls) (map E3x2 hitWls)
-    hitPoint w = intersectSegSeg' sp ep (_wlLine w !! 0) (_wlLine w !! 1)
+    hitPoint w = intersectSegSeg' sp ep (fst $ _wlLine w) (snd $ _wlLine w)
     hitFFs   = mapMaybe (collidePointFF sp ep (_randGen w)) (IM.elems $ _forceFields w)
     ffs = map (\(p,(_,i)) -> (p, E3x3 $ _forceFields w IM.! i)) hitFFs
 
@@ -75,7 +75,7 @@ thingsHitLongLine sp ep w
 
     walls = zip (map (fromJust . hitPoint) hitWls) (map E3x2 hitWls)
     hitWls = wallsOnLine sp ep $ wallsAlongLine sp ep w
-    hitPoint wl = intersectSegSeg' sp ep (_wlLine wl !! 0) (_wlLine wl !! 1)
+    hitPoint wl = intersectSegSeg' sp ep (fst $ _wlLine wl) (snd $ _wlLine wl)
 
     hitFFs = mapMaybe (collidePointFF sp ep (_randGen w)) (IM.elems $ _forceFields w)
     ffs = map (\(p,(_,i)) -> (p, E3x3 $ _forceFields w IM.! i)) hitFFs