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‫Hello and welcome back.

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‫Now we've created a tank that can move around and even rotate its turret.

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‫And we're ready now to create a tower class that can inherit some of the functionality that the tank

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‫inherited from the base pod class.

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‫Now, once we've created a tower class, we're going to override the tick function so that we can rotate

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‫its turret as well.

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‫So our goal here is to have the turrets rotate so that they're always looking at the tank.

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‫This way, when they start firing projectiles, they'll hit the tank sometimes as long as the tank isn't

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‫moving out of the way quickly.

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‫And we're also going to figure out how we can get a hold of the tank --.

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‫That way we can target the tank -- and rotate the towers turret toward the tank --.

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‫We're getting ready for some projectile combat.

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‫So I'm here in the editor and I'm going to go into our tune tanks folder where the base -- and the

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‫tank classes are.

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‫Now, I'd like to create a tower class based on the base -- class.

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‫Now, the way we did this with the tank class was we right.

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‫Clicked on base -- and selected create C++ class derived from based upon an alternative way is to

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‫go to tools and select new C++ class.

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‫And from here we can click the tab that says all classes and search for base --.

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‫And here we see our base -- class.

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‫If I select this and click next, now I'll be creating a new class based on base --.

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‫I'm going to leave it in the same path as all our other C++ classes and I'm going to call this tower.

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‫So let's click Create Class.

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‫So here's my new tower age and Tower Dot.

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‫CP Now the first thing we need is the tick function because the tower is going to want to rotate its

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‫turret to face the --.

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‫So we're going to override the tick function here.

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‫So I'm going to make a new public section and we're going to type virtual void tick, which takes a

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‫float called Delta Time, and this is an override.

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‫Now we'll get into more detail about virtual and override in future videos, but we're essentially taking

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‫the inherited tick function and creating a new implementation for it.

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‫So let's take the tick function and implement it here in Tower CP.

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‫Now we need to prefix the tick function name with a tower and the double colons.

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‫And as always, it's a good idea to call super tick and we need to pass in Delta time.

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‫Now what I'd like to do here is rotate the tank turret so that the tower is threatening the tank and

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‫ready to fire projectiles.

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‫But I'd like to do this only if the tank is in range.

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‫Now, in order to know whether or not the tank is in range, we need to know the distance from the turret

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‫to the tank.

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‫Now, here's a little gizmo that represents the origin of the world.

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‫In other words, the point in space where X, Y and Z are zero.

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‫Now, when we talk about an actor's location, we're talking about the vector from the origin to that

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‫location.

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‫And we can always get that location vector using get actor location so we can get the location of one

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‫of the towers and the location of the tank.

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‫And if we know those two locations, we can calculate the distance between them.

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‫Now, we could do this with vector mathematics, but the F vector class has a function called dist,

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‫and this function takes to location vectors and what it returns is the distance between them.

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‫So here in the tower CP file, in the tick function, I'm going to write a couple of notes just so we

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‫know what we're supposed to do.

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‫First, we need to find the distance to the tank after that check to see if the tank is in range and

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‫if in range rotate turret toward tank.

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‫So we have some to dos here.

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‫Now, in order to find the distance to the tank, we need to get a hold of the tank.

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‫Now, a good place to do that is in Begin Play.

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‫So in addition to the tick function, let's go ahead and override Begin Play.

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‫Now notice in Tank H, begin play is in a protected section.

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‫We're going to keep it protected in the tower as well.

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‫So we'll place the protected section just under the public one and will implement begin play just under

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‫tick.

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‫So let's go to Tower Dot, CP, implement, begin play fully qualify the function name and as you probably

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‫guessed, we're calling Super Begin Play.

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‫Now in order to get the tank and store it in a variable, we need a variable of type tank.

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‫So we're going to place that here in Towers H in a private section.

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‫Now this is going to be an A tank, it's a pointer and we can simply call this tank.

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‫And in order to avoid having to include Tank H here, we can forward declare we've seen how important

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‫that can be.

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‫So now we have this tank pointer and if we can figure out how to access the tank, we can store it in

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‫our tank pointer here and begin play.

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‫The first thing I'm going to do is include Tank H, so that way we can actually use the type.

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‫So how do we access the tank?

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‫Well, here's the unreal engine documentation for a handy function called get player pawn.

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‫It exists in a gameplay statics.

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‫So since I have this open, I'm going to go ahead and copy the include for gameplay statics and take

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‫a look at the syntax.

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‫It has two inputs a world context object.

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‫We already know how to handle that and a player index.

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‫And as we saw for single player games like ours, the player index will always be player zero and that

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‫will allow us to access the pawn corresponding to player zero.

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‫So let's call this function here in Tower Dot CP.

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‫I'm going to paste in the include for you gameplay statics and in begin play I'm going to set tank equal

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‫to you gameplay statics get player -- for the world context object.

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‫I can pass in this and for the player index we can pass in zero.

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‫Now check out the red squiggly.

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‫It says A value of type a pawn cannot be assigned to an entity of type A tank.

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‫This is the same exact issue we ran into when we were attempting to call, get controller and store

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‫the result in an A player controller.

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‫A tank is a child of a pawn, so we can't store a parent type in a child pointer.

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‫We have to.

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‫You guessed it, we have to cast.

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‫So we're going to take the value return from this and put it inside of a cast function call.

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‫So we're going to say cast and we're casting to a tank.

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‫And what we're passing in to cast is going to be this call to get player pond.

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‫So let's put that right there in the parentheses.

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‫And after the cast we will have access to the tank.

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‫So now that we have access to the tank, we can find the distance to the tank and a distance is a float.

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‫So we can make a local float variable called distance.

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‫And what we're going to set it equal to is the result of calling the F vector static function dist.

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‫Now dist takes two input parameters of type F vector.

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‫Now we want the distance between two points in space.

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‫One is the tower location.

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‫We're in the tower class so we can call get actor location and that gives us the location of the tower.

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‫But what about the tank?

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‫Well, we can call tank, get actor location, and now we have the distance.

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‫Now the only issue is that we're using the tank pointer without first checking to make sure it isn't

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‫null.

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‫So we have to say if tank first and then we can take this function call and drag it right here inside

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‫the if statement.

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‫So if the tank is valid, then we can access its location with get actor location.

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‫Excellent.

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‫Since we're working in this if statement, I'm going to move these other comments here inside of it

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‫because we know we can't check to see if the tank is in range, if the tank isn't even valid.

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‫So I'd like to challenge you to rotate the turret towards the tank.

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‫Now, we only want to do this if the tank is in range, we have the distance.

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‫So now we need a fire range variable.

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‫So create a float called fire range in the tower class and expose this with you property.

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‫We'd like to be able to edit this from the editor.

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‫Now you're going to check to see if the tank is in range.

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‫If it is called rotate turret and rotate turret needs a look at target.

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‫You're going to pass in the tanks location.

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‫So pause the video and implement this behavior now.

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‫Okay.

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‫So we need a fire range variable.

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‫So here in Tower H, we have a private section.

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‫We're going to make a float.

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‫I'm going to call this fire range and I'm going to go ahead and initialize it to a value of, say,

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‫300 F.

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‫But we'll experiment with this because it's going to be a you property.

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‫So you property.

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‫And since I'd like all of the tanks to have the same fire range, I'm going to make this and it defaults

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‫only.

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‫So that way we can only edit it on the default blueprint.

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‫Now if you made yours edit anywhere or maybe edit instance only, that's totally fine.

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‫It's really a matter of preference and we can change it later.

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‫I'm going to give it a category as well and I'm going to call this category combat.

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‫Let's go into Tower CP and we have this next point here.

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‫Check to see if the tank is in range, which means we need to check to see if distance is less than

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‫or equal to fire range.

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‫We have less than or equal to and not just equal to, because from frame to frame, the distance may

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‫actually be greater than fire range, one frame and less than fire range the next frame completely passing

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‫fire range.

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‫So it may actually never become exactly equal to fire range.

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‫In fact, with floating point values, two floats being exactly equal is quite rare.

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‫So we have this if check and if we get to the inside of it, that means distance is less than or equal

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‫to fire range.

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‫The tank is now in range, which means this comment can be moved right there.

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‫Now, if in range, rotate the turret toward the tank, that means we're going to call the rotate turret

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‫function.

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‫That's our protected function that we put in base pod.

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‫Now rotate turret takes a look at target and we need the location of the tank.

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‫So that's going to be tank get actor location.

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‫And with that we are now calling rotate turret only if the tank is in range.

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

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‫So we're back here in the editor and what we need to do is go into blueprints, pawns and find a BP

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‫pawn turret and open full blueprint editor.

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‫Now up at the top right, we see parent class base pawn, but we want our parent class to be the tower

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‫so we can go to class settings, parent class and search for tower and select it.

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‫Now our pawn turret is based on the tower class.

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‫Now let's see what happens when we hit play.

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‫Okay, so I'm moving the tank around.

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‫We're not in range, so we don't see any movement from the towers.

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‫But if I get in range, look at that.

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‫Now they're following me around and it looks quite threatening.

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‫Now 300 units is not that far away.

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‫So what I'd like to do is edit that distance.

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‫So from here in BP Pawn Turret, I'm going to select BP Pond Turret self.

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‫And here's the combat section.

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‫I'm going to go ahead and set this to about 700.

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‫Now, if I hit play, I'll see that they won't be rotating while I'm moving back here.

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‫But as soon as I get in range, now they're looking at me.

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‫Perfect.

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‫So in summary, we have created the tower class.

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‫We now have an enemy for the tank.

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‫We also rotated the tower's turret toward the tank in the tick function and we're only doing so if the

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‫tank is in fire range.

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‫We also exposed the fire range variable so that it can be adjusted in the blueprint.

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‫We're almost ready for combat.

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‫We'll start setting that up in the videos to come.

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‫I'll see you soon.