‫Welcome back.
‫In this video we will have a look at is trigger.
‫And you have seen physical bodies already.
‫You have seen colliders, all those kind of things.
‫Now let's add a new component, which is a trigger and it's actually not even a new component.
‫And that's the beauty, because it is simply the collider itself.
‫So you can make a collider is trigger.
‫For example, our player could be a trigger or a new object.
‫So let's create a new object into our game, a 3D object.
‫Let's go with a cube.
‫And what I will do with the cube, I will change the position to reset.
‫So I'm going to reset it and I'm going to drag it a little bit up and to the side.
‫Now let's change the scale of Y to, let's say five and the scale of X two.
‫Let's go with three.
‫So now we will have a wall here and maybe it's better if I move the wall to the side and change the
‫X to one and to Z two.
‫Let's go with four.
‫So now I have this huge ball here and what I want to happen is if I walk through or if the ball passes
‫into this cube, I want something to be triggered.
‫So I want something to happen.
‫For example, I want the whole thing to disappear.
‫So let's say I want the wall to disappear, which is this cube.
‫So let's give it a is trigger.
‫The cube itself gets an is trigger.
‫Let's have a look.
‫What that does is it deactivates its collider in terms of it's not a wall anymore so it's not a wall
‫that we cannot pass through anymore.
‫So now as you can see, our ball simply ignores it.
‫It just walks through.
‫So if we want this wall to do anything, whenever something passes it or hits it, then we need to create
‫a new script.
‫So I'm just going to call the script trigger script.
‫So let's go ahead and create a new script, right click create and then see sharp script and call it
‫trigger script.
‫Now I'm going to assign that trigger script to my cube.
‫So let's go ahead and add the component scripts and trigger script.
‫And now let's open trigger script up.
‫And there is only one thing that I need in here, so I won't need to start an update method.
‫And again, it's not that important that you understand the code in itself, but it's more important
‫that you understand the principles.
‫So whenever something needs to happen, when our object is hit by another object, we need to use the
‫on trigger enter method.
‫There's a method called on trigger.
‫Enter is called when the collider other enters the trigger and other could be our player for example.
‫So let's do that.
‫I just pressed enter.
‫I chose the on trigger entry method and now it's created for me automatically here.
‫So what I can enter here is, for example, print triggered.
‫So I'm just gonna print something onto the console and you will see what that does in a second.
‫So let's do that.
‫So now our cube, it's really important that our cube has this trigger script.
‫Now we run the code.
‫And let's pass through our trigger.
‫And as you can see on the console here, it says Trigger.
‫So now let's trigger once again.
‫Let's try to get the ball back.
‫There we are and let's hit it again.
‫You can see it's called three.
‫It was called three times already, and that's because we passed through it three times.
‫What you could use that for is, for example, to get rid of this whole game object.
‫So let's do that.
‫Let's go back into the code and we call Trigger now and we also call the destroy method.
‫And I'm just going to give game object.
‫So what that will do and I'm just going to use game object as the parameter, what the parameter is,
‫what the destroy method is.
‫If you don't know those things yet, we will get into that later.
‫So the destroy method, what it will do, it will simply destroy the game object that contains this
‫trigger script.
‫So that's what this line here says.
‫So let's have a look how this looks in game.
‫So I'm going to simply trigger this event.
‫And you see, our wall has disappeared.
‫So if we set up our game slightly differently, so I'm just going to go ahead and position my ball at
‫the bottom straight away and move it to the left.
‫And now I'm going to move my cube a little bit and I'm going to duplicate that cube multiple times,
‫and now I move the cubes one after the other.
‫So let's just move them.
‫And this one as well.
‫And the last one as well.
‫So now if I start it off, what will happen is that one after the other will disappear that we are.
‫I simply duplicated them with using control dx or command d based on which system you are using.
‫So right click duplicate is another option.
‫So if you duplicate it this way, then the object will be duplicated at the same position.
‫So that's why you cannot see that there are two objects.
‫So you need to move one in order to see that there are two objects, in fact.
‫So let's go ahead and do that again.
‫And now, as you can see, the destroy method is called.
‫Now, what we could do is deactivate.
‫That is trigger onto any of our objects or all of them are objects, at least of our cube objects.
‫So let's do that real quick, except for the last two.
‫And now what I want to add as well is a rigid body to all of them, or except while the first ones at
‫least.
‫So let's add a physics rigid body to cube cube.
‫One, two, three.
‫And that's it.
‫So physics.
‫Granted, Buddy, and add physics.
‫It's important that you use physics and not physics to DX because otherwise it won't work.
‫Now let's run it again.
‫And now let's try to hit it with our ball.
‫And as you can see, the first one still had a trigger.
‫Now, boom, boom.
‫And those two, they just fall off.
‫So the ones that had a trigger, they disappeared and the ones that didn't have a trigger.
‫So for five.
‫And I think that's it.
‫They had a trigger still, so they disappeared.
‫But the other ones didn't disappear.
‫Because they didn't have the trigger method activated and that's why they weren't destroyed.
‫So now let's get rid of the trigger method from each of them.
‫And what that will allow us to do is to have a little domino game.
‫So let's go ahead and hit them off.
‫Maybe we should make our player a bit bigger.
‫I'm going to pause the game again.
‫Go ahead and change the radius.
‫Or actually the scale of our player to, let's say three times three times three.
‫And let's drag it up a little bit.
‫And now what we could do is.
‫Go to here, you can use global or local.
‫So now we are global and now I can move your camera towards the front and move it up a little bit.
‫So now you have a better angle at things.
‫So let's start it again.
‫And now let's move it.
‫And as you can see, not all of them are moving.
‫Why is that one not moving?
‫Maybe you can figure it out.
‫As you can see now, I can move it just at the edge of it.
‫Maybe you know why it's not moving.
‫I hope you know it.
‫It is because it doesn't have a rigid body.
‫So Q.
‫Q one, two and three have a rigid body, but they are not here in the order of their naming, so.
‫Q One is the first one.
‫The cube is the right one.
‫Two is this one and three is that one.
‫So the fourth is the one to the right and the fifth is this one.
‫And those two, they don't have a physics body.
‫That's why they cannot be influenced by physics.
‫So let's change that.
‫Let's give them a physics body as well.
‫Physics and rigid body.
‫Now, let's go ahead and play that again.
‫Or maybe let's even get rid of this central one.
‫So let's delete this that cube here, delete and let's run it again.
‫And now let's hit it.
‫And as you can see, we have this little domino game here.
‫And let's try to get on top of it.
‫Yeah.
‫Perfect.
‫Our ball can with its force, it can move on top of it.
‫It can move around those objects.
‫And now you could go ahead and play, create your own little game, a little domino game or a little
‫collection game where you can collect game objects and make them disappear with the destroy method.
‫All right.
‫So that's it for now.
‫Regarding Collider's rigid body and its trigger.
‫We will use those extensively in our games.
‫So no worries if you don't really get a grasp of it completely yet.
‫But we will get there and you will see it within real games.
‫So see you in the next video.