Towards a better Selector

• When we left our game last time, we had a BP_DestSwitch that required us to step on it
  • I found it sort of annoying to have to go back and forth to be able to change multiple times.
  • There has to be a better way.
• A look at events
  • Events are things that happen.
    • We have seen overlap begin, and by extension end
    • We have seen hit.
    • In fact, there are the basic ones listed here
    • They provide some information on exactly what causes the event
    • And what receives the event.
  • When a given event "happen", the corresponding blueprint in the event graph is executed.
    • These items are sometimes called callbacks in other environments.
    • They are also called event handlers
  • They say that an event can only be listed once in each object's event graph.
    • This makes sense, as you can only do one thing when an event happens.
  • Most events are straight forward
    • With a collision you are given a pointer to the other actor
  • But some are much more complex
    • A hit event has 8 or more inputs.
    Apparently the main loop of the game is called a frame
  • And the Event Tick event occurs every iteration.
  • Looking about there appears to be a set of keyboard events.
• That gives me an idea. Let's build a class that responds to keypresses
  • Just a collision box and a cube to show where it is.
  • It needs a local variable active
    • This will be true, when the player is "in" the box.
    • Initialize it to be false.
    • When the player has an overlap, set it to be true
    • When the player is not longer overlapping set it to be false.
  • Add a Event Keyboard, let's just pick B
  • 
  • But when I run it, it doesn't Fire.
  • It turns out, they have turned off input.
  • But we can turn it on.
    • There is an enable input node
    • It takes a player controller.
    • If we were in a multiplayer game, we would need to worry about this, but for now how about
    • 
  • Probably should turn it off when we are not using it.
    • You can do this with a Disable Input
    • This eliminates the need for a "active" variable.
  • Just for fun, I added a right mouse click as well.
  • 
  • One last piece. Let's tie this to a transporter.
    • Build a new variable of type BP_Transporter
    • Expose this to the outside world.
  • Now I want to be a bit careful.
    • I don't want to call a function if this is not hooked to a transporter
      • This would be a configuration problem.
      • But just be careful.
    • So I am going to check to make sure that it is not null
    • In BP, this is the default value
    • 
  • I am happy.
• Quick Aside, What buttons are used?
  • We can't tell what buttons are used in other blueprints.
  • But we can see what is mapped in the player controller.
  • Edit Project settings.
  • Select Input under Engine
  • Explore the bindings.
  • Create a new binding
  • 
  • Access it in the first person character.
  • 
• Be careful with the event Any Key
• This takes keys away from the controller.
  • 
• On last note on events
  • you can build custom events.
  • There appears to be little difference between these and functions.