Start making projectile update function rather than folded list

src/Dodge/Projectile/Update.hs

@@ -26,10 +26,10 @@ updateProjectile pj w = foldl' (flip $ upProjectile pj) w (_pjUpdates pj)
 
 upProjectile :: Projectile -> ProjectileUpdate -> World -> World
 upProjectile pj pu = case pu of
-    CollisionEffectPU mdetonatorid mscreenid ->
+    CollisionEffectPU ->
         shellCollisionCheck
-            mdetonatorid
-            mscreenid
+            (pj ^. pjDetonatorID)
+            (pj ^. pjScreenID)
             pj
     TimePU -> decTimMvVel pj
     ThrustPU st et
@@ -79,7 +79,7 @@ applyGravityPU pj w
         | otherwise = x * 0.9
     newz = pj ^. pjZ + pj ^. pjZVel
 
---shellCollisionCheck :: (Projectile -> World -> World) -> Projectile -> World -> World
+-- consider using thingHit, pushing any hit creature back
 shellCollisionCheck ::
     Maybe (NewInt ItmInt) ->
     Maybe (NewInt ItmInt) ->
@@ -174,12 +174,9 @@ decTimMvVel :: Projectile -> World -> World
 decTimMvVel pj =
     cWorld . lWorld . projectiles . ix (_pjID pj)
         %~ ( (pjTimer -~ 1)
-                . (pjPos %~ (+.+ vel))
-                . (pjDir +~ rot)
+                . (pjPos +~ _pjVel pj)
+                . (pjDir +~ _pjSpin pj)
            )
-  where
-    rot = _pjSpin pj
-    vel = _pjVel pj
 
 explodeShell ::
     Maybe (NewInt ItmInt) ->