ShmupWorld: pad screen bounds for reaping objects

Shared/ShmupWorld.cs

@@ -89,15 +89,19 @@ namespace SemiColinGames {
     }
 
     public void Update(float modelTime, History<Input> input) {
+      // Update player & shots.
       ProfilingList<Shot> newPlayerShots = Player.Update(modelTime, input, Bounds);
-
       foreach (Shot shot in Shots) {
         shot.Update(modelTime);
       }
 
+      // Add new shots.
       Shots.AddRange(newPlayerShots);
-      // TODO: inflate bounds rectangle
-      Shots.RemoveAll(shot => !Bounds.Intersects(shot.Bounds));
+
+      // Reap off-screen objects.
+      Rectangle paddedBounds = Bounds;
+      paddedBounds.Inflate(16, 16);
+      Shots.RemoveAll(shot => !paddedBounds.Intersects(shot.Bounds));
 
       Debug.AddToast("shots: " + Shots.Count);
     }