A Spawner

• Based on the previous work, I decided to build a spawner.
  • This is responsible for "spawning" new objects.
  • It will only spawn one thing at a time.
  • When that thing "dies" it will wait and spawn something else.
• To start off, I build a collision box with lights in the four corners
  • The collision box will provide bounds in which items will be spawned.
  • The lights are just to show the corners.
• I built a function SpawnNewItem

  • BP_Spawner
       Actor[] ClassToSpawn{BP_Pickup_Child_Damage, BP_Pickup_Child_Health, BP_Pickup_Child_Ammo};
       New Event: ChildDiedEvent (an event dispatcher)
    
    
       BeginPlay()
           BindEventTo(ChildDiedEvent, ChildDiedEvent_Event);
           SpawnNewItem();
    
       ChildDiedEvent( )
           Set A Timer to Call SpawnNewItem(rand(1...5));
       

  • Timers are something that exist in operating systems.
    • A simple tutorial
    • Think of them like an alarm clock.
    • The will, some time in the future, call a function.
    • They take
      • a callback (a function to call when the timer expires)
      • A time to delay (float in seconds)
      • A bool that indicates if the timer should recur or not.
    • When the time has passed, they function will be called.
    • This is probably more efficient than the delay node.
    • This is probably what the delay is based upon.
    • You can clear timers if you wish.

• BP_Spawner (continued)
  
  SpawnNewItem()
  
      bounds = Box.GetComponentBounds();
      newLoc = RandomPointinBoundingBox(bounds)
  
  
      class = ClassToSpawn[rand(0..ClassToSpawn.Size()-1)]
  
      newItem = SpawnActor(class,newLoc)
      newItem.MySpawner = this;
       

• I modified the BP_Pickup_Parent
  • I added a MySpawner variable of type BP_Spawner
  • I added a function

    • 
      Event FinalDestruction
          DestroyActor()
          mySpawner.CallChildDiedEvent() 

  • I modified all of the derived pickup classes

    • 
      PickupGrabbed
          // local code for action
          ...
          // this is a call to the event created above.
          invoke FinalDestruction()