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In this lecture, we're implementing our game sessions so that we can keep track of how many lives the

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player has.

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But and when we drop into some spikes, drops down to one.

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If we go all the way down to zero lives, then it will reset us back to the very first level.

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Let's look at what we're trying to achieve here with our goal.

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I want to have the player have a certain number of lives, probably three for me.

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I want to have the scene restart when the player dies so that you go back to the start of the scene

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or start the level and try to do it all over again.

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And when all the players lives are lost, I want the game to be over and reset all the way back to the

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first screen, or if we've got a main menu or the very first in our build index, most likely.

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So that's our goal.

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There's a problem.

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However, after death, reloading the scene re instantiating the player and all other objects.

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So it loads everything again.

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And any progress we have with our player or our scene is going to be lost.

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So we don't want to have that if the player has a certain score, if we've picked up a certain number

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of coins, if the player has a certain number of lives, then we want to retain that.

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We don't want to have all that loss when we restart the scene.

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So what I'm going to create is a game session object which will be responsible for all these things.

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It'll be game session.

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CSS is our script and it will be responsible for our lives and our dying, for our score, for level

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progress.

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So what level we're on, as well as restarting the game when we have run out of lives and anything else

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that we want to persist throughout our game session.

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So let's scootch back over into Unity.

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I'm going to create myself a new game object.

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I'll do this within level one and then prefab it and pop it into the other levels as we go.

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So right click Create Empty.

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I will call this game session, game session and I'll reset that back to the zeros.

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Now in my scripts folder, I'm going to right click create a C sharp script.

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I will call also game session and clicking on game session.

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I will drag game session onto game session.

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How many times can we say game session and what we're here for?

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A bit of fun.

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I'm going to click on my Prefabs folder and drag the game session down into the Prefabs folder.

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So we've started that particular process or double click on our game session script.

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Open that up.

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I'm going to get rid of the bits and pieces.

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We don't need a bit of tidy up here.

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Now the first I'm going to do, instead of using Start, I'm going to use a wake.

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So if you remember our unity order of execution, awake is the very first thing that is going to happen

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when we push, play, push our play button.

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So within a week, what I want to do is find out how many of the game sessions we currently have.

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What I'm doing here, a little bit of a spoiler.

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I'm going to implement a singleton pattern.

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And the singleton pattern is a way for us to say we only want to have one particular thing in a single

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a single thing.

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And when we click on play, we'll have this one game session object.

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We only want to have one because if we then reset the level or restart the level, we don't want to

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have a new one appear.

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We only want to have one of these.

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So right at the very start, we're going to find out how many game sessions we have.

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I'll store this in an integer, which I'll call NUM as a number of game sessions, right equals.

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And this will be find objects of type with an s.

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I sometimes get this messed up, so I'm going to make a really big deal out of the SFU so you don't

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mess up as well.

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Objects of type.

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This is going to create an array because there's many things.

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There's possibly more than one thing find objective type finds the first thing, but objects of type

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finds all the things I'm going to be looking for game session and that goes in our angle brackets and

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then parentheses.

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Dot we want to know how many game sessions we have because this is an array.

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Can you have a think of how we would go about finding how many items are in the array?

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We use length that will tell us how many things are in the array.

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Now we need a little if statement in here if our number of game sessions is greater than one, so we've

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got more than one.

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What do we want to do?

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Well, we destroy whatever appears.

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We destroy the game, object, semicolon.

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And so a wake is going to be called whenever this class wakes up or comes alive or is brought to life.

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The first time that happens is when we push the play button.

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This game session with its script on it will blink, come to life.

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It also happens when we die and we restart this scene so that we freshly go back to the start of it.

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When we start that, it's also going to awaken a new script.

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So at that stage or a new class at that stage, if something already exists, if there's already one

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in there, so this new one makes the second one, then we destroy this new one.

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However otherwise or else is how we write otherwise.

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Then don't destroy on load.

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And once again it's the game object.

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So that's our way of saying each time you load a scene, don't destroy it, have it, stick around,

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have it stay there.

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There's another couple of things I'm going to do in here.

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I'm going to remove update.

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I don't think we're going to need that next stop.

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I'm going to create a public method that I can call from somewhere else.

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Call from the player script, I think is where we'll call it.

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So public void process, player death is what I'll call this death.

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And within here I'm going to add two methods, one of which I'll do with you now, and the other I'll

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set as a challenge for you.

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Start by adding an if statement, if the player lives and we need to create a variable for this.

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So if player lives is greater than one.

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So in other words, you still have enough to keep going.

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Let's jump up and create this now.

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So I will create a serialized field.

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It will be of type int.

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We don't want to have a fraction of a life.

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We'll call this player lives.

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Player lives.

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It looks like the player leaves now its player lives will initialize that at three, give the player

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three lives.

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So back down into here.

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If player lives, what have I done wrong?

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Play lives.

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Play lives.

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Well, I've had an extra se down there.

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I'm in the habit of the find objects of type.

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I'm find everything's of type players of lives.

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So okay, just player lives greater than one as per the variable we've just made.

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Then we want to do something.

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Well, we'll call this for now.

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Take life.

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So take a life of the player.

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It's a method.

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We'll create that in a moment, else or otherwise.

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We want to do what?

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Well, I'll make this as a method as well.

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There's only a couple of lines, but it's nice.

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It reads more nicely.

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If we've got separate methods for these, we'll call this reset game session.

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So basically, if you're at the point where you've lost all your lives, we want to reset that.

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So I want to say the single turn, just reset, start a new session.

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So let's create reset game session together.

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Then I'll get you to do take life as a challenge so I can click on game session control period or control

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full stop.

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Generate this method that'll generate down below.

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Just clean it up a little bit void.

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And then we don't want to throw an exception.

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We want to put some content in here.

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So when we reset the game session, we want to first of all, access scene manager and because it's

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not showing up, it means we haven't used that.

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Once again, I can hit control period and then add the using unity scene management that will plop that

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up at the top.

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Yes.

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Thank you.

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Scene management.

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Good.

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Now we should know scene manager something we want to do.

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What?

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We want to load the very first scene.

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So I'm going to hard code this in load scene zero assuming that the very first thing we come across

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is going to be the main menu or the first level for now, it's just the first level.

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Later on, we might need to come back and change this, but I think this is okay for the moment.

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Just saying go back to the first level or first scene we have in our entire build at this point in time.

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And then when we do that, it's really, really important that we destroy this thing, destroy this

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game object.

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So we're destroying this instance of the game session so that if someone's playing this and they push

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play again, we don't have all this stuff hanging around.

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We get a totally fresh new instance of the game session.

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That can be the first one that when other ones come along and says, Oh, there's already one here,

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but at some point we need to reset it back to having none of them.

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That's what we're doing here.

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When we destroy the game object, that's most of what we need in here.

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The last thing I'm going to give to you is a challenge.

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Take life, so finish processing the player.

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Death reduced the number of lives when the player has some sort of death incident.

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And then to load our current scene that we're currently on when that happens, we've done this a couple

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of times in this section, so there's some code you might want to go look at and grab, but there's

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your challenge, plus video.

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See you back in when you're done.

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So take life.

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I'm going to control period to generate that as a method, clean it up a little bit, get rid of our

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exception.

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First thing I want to do in here is player lives.

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Now I'll write it the long way then the short way equals player lives minus one.

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Now the quicker way we can write this, it's exact same thing is to say player lives minus minus.

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That will decrease whatever the current value is by one.

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Now we need to load where we currently are and we've done this before.

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I'm going to use it because our build index is an integer.

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Current scene index equals scene manager dot get active scene.

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What's the active scene we're looking for?

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Well, we need to know from the build index what its number is and then we're going to load that.

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So scene manager, dot load scene and we're loading the current scene index semicolon.

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Now the last step we need to do because we created a public method process player death that goes through

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all of this kind of stuff on the game session.

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We need to find a place to call that, so I need to open up my player movement script.

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It's a little bit more than player movement, but I'm okay.

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We could rename it to player, we could break it out into a number of different scripts.

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But I'm okay for now because there's no confusion.

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There really is only one thing in here when we move in a way that causes us to die.

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Well, we want to be reloading certain things.

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Let's have a look at where we've got die in here.

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This is a big class now, isn't it?

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Die if this happens.

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Bump, bump, bump down at the very bottom.

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We're going to look for our game session.

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So find object of type.

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Object of type.

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In this instance, we want to find the one that exists for an object of type.

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We're looking for game session parentheses, full stop.

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And we're going to call which method?

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Hopefully the one we just created.

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Process player, death, parentheses, semicolon and we'll say we'll see how this works.

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Probably need to first of all, go and throw this into all of our other levels.

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So I'll just do that quickly.

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Jump into levels.

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Level two, save level one.

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Yes, level two.

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We need to grab our prefabs and put in game session into the level.

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Save that up over to our levels.

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Fine level three prefabs game session save.

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So I'm going to go back to level one just because it's nice and simple and we can go through this process

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quite quickly.

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If you click on play, you'll see it don't destroy on load.

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If we expand the don't destroy on load, you can see the game session in here.

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Player lives run, run, run, drop.

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It's down to two, down to one, down to zero.

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And then it should reset.

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Once again, we get a new game session and it's back up to three.

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I just noticed one bug that I just found just now.

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I click on play if I shoot bump.

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It takes us to the next scene.

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Okay, let's fix that bug really quickly now.

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I don't want to take up too much time in this particular lecture.

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If we click on the play off, just going to tag the player as player and then jump over into one of

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my scripts.

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Which one?

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This is going to be the level exit.

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Open that up.

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What do we need to do in here?

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Little micro challenge for you.

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Pause the video and see if you can have it.

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So only the player starts the code routine.

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Well, it should be reasonably straightforward if other tag equals equals parentheses player, make

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sure we spell it exactly right.

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Wrap our curly braces around the stock code routine.

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Pop that in there.

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Get our formatting figured out.

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We'll save that.

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Hopefully, that's going to work.

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Just do a little bit of a test on this.

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I totally didn't realize we had that bug until I saw it accidentally just now.

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I was trying to click on one thing and I shot Let's see if I shoot now at the level exit editor I'm

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shooting.

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Nothing's happening.

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If I run down and run through it, I'm the player.

236
00:12:06,190 --> 00:12:06,670
Yes.

237
00:12:06,670 --> 00:12:11,510
And the player is recognize game session is still telling us we've got three player lives.

238
00:12:11,530 --> 00:12:14,830
Let me just run into the spikes to make sure I haven't broken anything with that.

239
00:12:14,830 --> 00:12:15,630
And that's all working.

240
00:12:15,640 --> 00:12:15,850
Cool.

241
00:12:15,850 --> 00:12:16,420
There we go.

242
00:12:16,450 --> 00:12:18,220
We fixed the bug as a bit of a bonus.

243
00:12:18,220 --> 00:12:19,240
That's very exciting.

244
00:12:19,240 --> 00:12:21,010
That's what game development is all about.

245
00:12:21,010 --> 00:12:22,330
Making bugs and fixing bugs.

246
00:12:22,330 --> 00:12:23,200
So great stuff.

247
00:12:23,200 --> 00:12:24,430
I'll see you in the next lecture.