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‫Welcome back.

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‫Now we have a game mode and we'd like to use the game mode to determine when we can start the game.

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‫Now, some games have a delay or a countdown timer that starts when the game starts.

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‫And after a set amount of time, then the player is allowed to move the character or in our case, the

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‫tank around in the world.

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‫So we're going to implement that in this video.

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‫This is going to involve first disabling the input so we can't move around when the game first starts

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‫and then we're going to set a timer and after a set amount of time, then we can enable input.

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‫So let's go back to tune tanks game mode and add a couple of things here.

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‫First, I'd like to add a float for the amount of time that should pass when the game starts before

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‫we can start moving.

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‫So this float is going to be called start delay and I'm going to initialize this to three point F so

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‫that we have to wait 3 seconds before we can start the game.

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‫Now, as soon as the game starts, I'd like to start this timer, which means I'd like a function that

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‫will start this timer, and I'm going to make this a private function as well.

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‫I'm going to make this a void function called handle game start.

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‫Now I can implement handle game start in tune tanks game mode.

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‫Step down here under begin play.

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‫Now I won't forget to add the tune tanks game mode class name here and now I have a handle game start

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‫function.

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‫Now the place to call this would be Begin Play.

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‫Since Begin Play is called at the start of the game.

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‫So I'm going to call handle game, start here and begin play.

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‫And since we're doing a couple of things here at the beginning of the game where setting the tank and

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‫the tune tanks, player, controller variables, I'd like to move these into handle game start.

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‫So I'm going to move those right down into handle game start and that way tank and tune tanks player

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‫controller will be set since we're calling handle game start here and begin play.

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‫So here is where I would like to start a countdown timer after which we can enable user input.

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‫Now before we start the timer, I'm going to disable input so we can't move the tank just yet.

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‫And that's going to require our function.

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‫We placed here in tune tanks, player controller called set player enabled state.

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‫And that means I'm going to use tune tanks, player controller.

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‫And if I'm going to use tune tank's player controller, it's a good idea to make sure it's valid.

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‫So I'm going to say if tune tanks, player, controller and if we reach the inside of this if statement,

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‫then I can take tune tanks, player controller and call set player enabled state and pass in false.

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‫And that way our tank will not be able to move.

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‫And I see the red squiggles and that's because I said tank tanks, player controller rather than tune

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‫tanks.

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‫So spelling it correctly now I get no errors there.

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‫So next we need to start a timer.

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‫Now we know that timers involve using an F timer handle and we can actually create an F timer handle

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‫rather than having a member variable that belongs to the class.

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‫So I'm going to go ahead and do that and I'm going to call this player enable timer handle.

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‫And next, we need to set a timer now for the callback function for our timer, I'd like to use set

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‫player enabled state, but set player enabled state is a function that requires an input of type boolean.

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‫Now we haven't seen how to set a timer using a callback that requires input parameters.

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‫This is going to involve a new concept called a timer delegate.

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‫So let's take a look at Unreal Engine's timer system.

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‫Again, we know that there's a world timer manager which manages our timers and it has a set timer function.

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‫Now there are multiple overloads of the set timer function.

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‫We've seen one of them already.

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‫Now I'm going to talk about another version of this function.

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‫And this version requires a timer handle, a timer rate or a delay time during which we must wait before

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‫our callback function gets called.

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‫And instead of taking the address of a callback function directly, it can take something called a timer

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‫delegate.

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‫This is a struct of type F timer delegate, which allows us to create an object that can bind a function

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‫directly to it.

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‫And timer delegates can bind functions that require input parameters.

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‫Now we can create an EF timer delegate variable and initialize it using the create you object function

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‫from f timer delegate.

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‫This will create a new timer delegate and initialize it based on what we pass into the parentheses.

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‫This will take a user object which is of.

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‫Of course, the class that our callback function exists on.

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‫And next it takes the address of the callback function itself, followed by any input values that we

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‫would like passed into our callback once it gets called.

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‫From there we can call set timer from the world timer manager and use the overload that takes a timer

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‫delegate.

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‫This overload requires the timer handle itself, the timer delegate, the play rate or a float that

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‫determines the delay before which our callback will be called, and then a boolean to determine whether

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‫or not our timer should loop so we know how to create an F timer delegate.

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‫So I'd like you to create one in the handle game start function inside of our new if statement.

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‫So create a local f timer delegate and use f timer delegate.

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‫Create you object.

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‫Now we're going to need to pass in a user object and usually we've been using this as the user object,

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‫but the function we'd like called exists on the player controller.

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‫So pass in are variable tune tanks player controller as the first input that's going to be the user

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‫object and the callback function is going to be set player enabled state that function we added to our

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‫custom player controller.

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‫Don't forget the address of operator and as the third input we're going to pass in the value.

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‫True, this is what will be passed into set player enabled state when our callback gets called at the

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‫end of the timer.

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‫So pause the video and give this a try now.

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‫So just under our timer handle, I'm going to create a local F timer delegate and I'm going to call

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‫this player enable timer delegate.

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‫That's okay.

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‫If you named it something else.

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‫Now I'm going to initialize this using f timer, delegate, create you object.

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‫And this will first take a user object and that's going to be our tune tanks player controller.

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‫So I'm going to say tune tanks player controller as the first input.

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‫And for the second we need our callback function and that's going to be a tune tanks player, controller

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‫set player enabled state.

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‫And I can't forget, I need the address of operator for this function address and the value that I'd

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‫like passed into this callback function is going to be true that way.

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‫At the end of the delay time, when this callback gets called true will be the value passed in to the

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‫callback function.

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‫Now I'm ready to call set timer, which means I need to call get world timer manager.

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‫And then from there I can call set timer.

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‫And the function overload we're using first takes a timer handle and that's going to be player enable

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‫timer handle.

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‫The next input I'm going to pass in will be the delegate.

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‫So that's going to be player enable, timer delegate.

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‫Next.

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‫We need our delay time and that's going to be start delay, which is the float we just created.

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‫So next I'm passing in start delay.

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‫And finally, I don't want this timer to loop, so I'm going to pass in false so that we don't get looping

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‫behavior.

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‫Now I'm going to go ahead and indent these inputs so it looks pretty.

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‫And now we're calling set timer using our new timer delegate.

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‫And at the end of this delay time we should get our callback function set player enabled state called

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‫with the value true passed in now since start delay is 3 seconds and we're calling set player enabled

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‫state passing in false before we set our timer.

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‫When we press play, we shouldn't be able to move until this three second delay is up.

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‫So let's compile this and see how it works.

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‫So I'm going to go ahead and hit play and I'm trying to move around and I can't.

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‫And after 3 seconds I can suddenly move.

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‫And also check this out.

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‫Notice that my cursor is the crosshairs.

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‫It may be hard to see on the screen, but you should be able to see it on your screen just fine.

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‫And this makes it a lot easier for me to aim and control my tanks.

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‫Turret rotation.

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‫Perfect.

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‫So in summary, we created a handle game start function for the game mode and we're calling this and

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‫begin play.

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‫And we also set a timer using a timer delegate onto which we bound our set player enabled state function

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‫on the player controller.

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‫This allowed us to have a function callback for our timer that takes input parameters and we use this

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‫to enable user input after a three second delay when the game starts.

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‫Now, this could be frustrating for a player if they didn't have some sort of visual cue, sort of letting

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‫them know that input is not enabled.

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‫Something like a countdown on the screen.

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‫So we'll take care of that in future videos.

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‫But for now, congratulations.

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‫You now know how to bind a function that takes input parameters to a timer delegate.

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‫I'll see you in the next video.