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‫Hello and welcome.

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‫In this lecture, we're going to be introducing this piece of code here, the RT actor range, and see

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‫how it allows us to iterate over all of the actors in a given level.

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‫Let's dive in and see how it works.

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‫So at the moment in the pawn killed of our kill all game mode we are calling game has ended on the player

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‫controller but in actual fact game has ended is a function on all controllers where there A.I or player

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‫controllers and we should probably be notifying the AI controllers as well that the game has ended and

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‫that's certainly going to be the case or it's going to make it easier to do a win condition as well

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‫because we won't necessarily have the player pawn coming in here.

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‫So how do we go ahead and do this?

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‫Well, I'm going to create a new function in the KML game mode, a private one called End Game, which

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‫is going to be responsible for this act.

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‫So End Game and it's going to need some information.

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‫It's going to need to know who has won.

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‫Has it been the player or has it been the A.I.?

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‫So I'm going to create a bool here called B is player winner.

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‫And that is going to be what tells us whether or not we should be telling the AI that it's won or telling

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‫the player that it's won.

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‫Because remember in here our game has ended.

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‫Takes a boolean telling the controller whether or not it is one of the winners.

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‫So what we're going to have to do is figure out, first of all, let's go ahead and create the implementation.

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‫So I'm going to do my control shift P and then create implementation.

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‫And then we're going to have to figure out how we can find all of the controllers in our scene so that

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‫we can call game has ended on those controllers.

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‫Now the way we're going to do this is using a an engine helper call.

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‫So if we go to hash include, we're going to use engine utils, first of all.

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‫And that's going to bring into scope the helper that I want and the helper is called T Actor Range and

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‫T actor range is a template thing.

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‫So we can do the angle brackets here.

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‫We can then put a controller and then the parentheses and get world.

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‫Now what's this going to do?

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‫It's going to return us a range object, which is basically sort of like a list that goes over all of

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‫the controllers.

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‫That's why we've got that controller parameter in there in the world a.k.a the level, and we can use

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‫this in a for loop.

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‫So let me start wrapping this in a for loop.

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‫So we're going to do a for over the A controller.

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‫So the thing that is the variable that we're going to be ranging over is going to be an A controller

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‫pointer, which I'm going to call controller.

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‫And then we use the colon for what we're going to range over.

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‫It's going to be this T active range.

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‫And then we can put our closing parentheses and our curly brackets.

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‫So what's this saying?

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‫It's saying that we're going to do a four loop over every controller in the world and it's going to

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‫be in this variable called controller.

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‫And now there's a couple of things that you might need to know.

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‫So one thing is that we can query a controller for whether or not it's a player control without having

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‫to cast.

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‫We can actually just do controller arrow and then I think I'm going to actually need to include my controller

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‫here.

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‫So hash include at the top, we're going to do a game framework forward slash controller H and now Autocomplete

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‫will probably work.

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‫Yes, it has.

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‫So what we can do is obviously we can call game has ended.

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‫That's what my first autocomplete here but also we can say is player controller.

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‫Basically it's going to say is this thing in the world of player controller and that will allow us to

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‫decide whether or not we should be passing in true or false to game has ended.

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‫So my challenge to you is to fill out this for loop by calling game has ended with the correct boolean

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‫parameter.

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‫So we're going to do this so that basically it should be true if the if the controller that we're talking

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‫to the controller currently in the for loop is a player controller and the boolean that we had passed

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‫in says that the player controller is the winner should also be true.

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‫If it is not a player controller and not the player, the player is the winner basically saying if this

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‫is an ally and the I is the winner false if the player controller but the player isn't the winner and

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‫false if not the player controller, but the player is the winner.

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‫You kind of see where this is going, hopefully.

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‫So pause the video and have a go at implementing it like this.

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‫You might use if statements.

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‫You might use some other logic to allow you to calculate this boolean pause video and have a go.

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‫Okay.

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‫Welcome back.

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‫So you could do this a number of ways.

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‫One way might be to say if the bee is player, control a winner and then we're going to put something

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‫in this if statement we might do a bool up here to decide that basically B is player controller.

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‫Which we're going to save from the fact that we do a controller.

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‫Arrow the is player controller like so.

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‫And then we might say, okay, well we want to call controller.

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‫Arrow game has ended.

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‫We're going to pass in the null pointer for now.

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‫And then we're going to say, well, if it is a player that is the winner and we are a player controller,

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‫then yes, basically go with that value.

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‫So play a controller.

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‫Otherwise, if it's not the player controller, it's going to have lost.

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‫And we can just negate this so we can say else there we're going to do call the controller game has

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‫ended with not is player controller basically because we're saying the player is not the winner, the

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‫eye is the winner in this statement.

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‫And so what we want to do is say that the depends on whether basically the opposite of whether the player

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‫has won, which is to say that the eye has won.

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‫So that's one way of doing it for sure.

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‫But there is another and simpler way, which is simply to say, are we the winner?

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‫So be is winner.

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‫And this can simply be to say that whether you are the player controller is equal to be is player winner.

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‫Now let's think about this a little bit more and I'll just complete this fully and then we'll talk about

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‫it.

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‫So we're going to say controller game has ended is going to be the null pointer with the be is winner

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‫passed in here.

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‫Now, why does this statement work?

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‫Well, let's think about the cases, right?

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‫So we have a player controller in here and the player is the winner, then?

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‫Yes, we are the winner and they are equal.

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‫True and true.

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‫How about if this is not the player controller and the player is not the winner?

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‫Well, then this is false.

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‫And this over here is also false so that the two of them are equal and the result is a winner.

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‫Is that true?

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‫Yes, because if we are the AI and the AI is the winner, then we should be the winner.

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‫Otherwise, if these two are not equal, i.e. that we've got an AI controller, but the player is the

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‫winner, or we've got the player controller and the AI is the winner, then we're going to have a true

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‫and false or a false and true.

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‫These two aren't going to be equal and the boolean is going to evaluate to false.

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‫So you can see that in each of the cases and I've gone through all of the cases there, this ends up

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‫with the right answer.

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‫So we know that this is the right answer.

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‫This is the great thing about Booleans is that usually you can evaluate all of the cases because you

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‫can say, okay, well, what are the cases?

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‫It's going to be true and true.

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‫It's going to be true and false.

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‫It's going to be false and true.

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‫It's going to be false and false.

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‫You can evaluate all those cases.

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‫If all of those cases are correct, then you know you've got a correct Boolean statement.

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‫Cool.

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‫So that's how we're going to calculate the B is winner.

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‫Finally, we just need to call our end game mode.

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‫At the moment we're doing a direct call to the play controller game has ended and what I actually want

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‫to do here is go ahead and call end game and we want to pass in false because this is a situation where

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‫the player has actually lost and that's basically what we want to achieve.

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‫Now, one more thing to note here is that this null pointer we've been passing in is going to lead us

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‫to problems down the road, because if the player has actually won, it's going to try and take away

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‫the focus from our player pawn.

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‫So what we want to pass in here is simply that the focus should be on the controller, dot get pawn.

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‫And that's basically saying that you should put the focus of your own player controller, be it basically

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‫where should your camera be pointing?

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‫It should still be pointing on your pawn.

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‫Why is it important that we do this and why is there this option here in the first place?

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‫Well, in a lot of games, you often or a lot of match style games, you might have that if the game

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‫has ended, you want to go and follow the pawn.

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‫That was the winner.

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‫So imagine like a Fortnite scenario, you often go and follow the person who killed you.

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‫This is the mechanism for doing this.

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‫You basically pass in the pawn of the person who did the killing.

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‫That's not what we're doing in our game.

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‫We're going to carry on looking at Apple and whether we'd win or we die.

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‫So that's pretty much it for the lecture.

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‫Let's just compile and see whether it's working.

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‫Let's dive on over into Unreal and hit play.

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‫Let's go and get ourselves killed.

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‫There you go.

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‫Everything's working as before.

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‫We're still getting that call to the player controller and then we restart.

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‫Great stuff.

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‫So in this lecture, just to recap, what have we seen?

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‫Well, we've seen how we can iterate over actors in the level in order to do something like calling

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‫a function on each of those actors.

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‫Next lecture we will be using the T actor range again, this time to calculate whether the player has

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‫won.

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‫See you there.