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‫Hello and welcome.

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‫In this lecture, we are going to be setting a blackboard key from our C++ so that we can set the player's

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‫location at Begin Play.

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‫Let's dive in and see how that works.

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‫Okay.

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‫So as I said in the last lecture, we want to be able to set some state from our gameplay in the blackboard

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‫for the AI to act upon.

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‫So the blackboard looks like this and it currently has this self active key, but it doesn't have any

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‫other keys here.

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‫We can add keys like clicking on this new key button.

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‫You can change the type.

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‫There isn't actually a type for actors or anything like that that just goes under the nebulous type

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‫of object for everything else.

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‫There's balls, classes, enemies, etc. but you can choose what kind of type that you want that object

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‫to be by going to your blackboard details, dropping down and choosing what base class you'd like.

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‫So for example, it's saying here that the self actor is of actor type.

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‫This has just been put in here by default.

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‫But what we want to do here is set a new key.

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‫And to do that, we need to do find out how we can gain access to this in the C++.

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‫So we already have an easy function that allows us to get hold of the blackboard by doing a get blackboard

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‫component on the AI controller.

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‫So simple as we can just do get blackboard component and let's have a look at that blackboard components

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‫dot h and have a look what is available in here.

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‫We want to be doing something like set key or set blackboard or in fact, it's as simple as just set

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‫value.

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‫So here you've got a bunch of different functions on that blackboard component that allow you to set

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‫these different values so you can do it by a key name, which is an F name here.

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‫Then you can set the value as an object, or you can set the class all of the different types that are

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‫available here.

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‫So let's give that a go.

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‫I'm going to go over to the C++ and try and set our player pawns location as one of the variables.

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‫So we're going to do first of all, we need to get hold of the blackboard component.

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‫So let's give that a shot, get blackboard components.

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‫Then we need to have the right includes.

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‫So if I hover over the blackboard component on H, you can see that we need to be including behavior

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‫tree forward slash blackboard component.

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‫So let's do that hash include then it's going to be the behavior tree forward slash blackboard component

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‫H.

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‫Now we can use the arrow operator on that type and we should be running.

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‫We want to, in this case be setting a vector.

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‫We want to set the location.

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‫So we're setting a vector and not copy the whole line, but just set the vector and then we want to

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‫what's the first parameter is the name that we're trying to set so we can use our text macro for that.

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‫And I'm going to call it the player location that's going to give us the location at the start because

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‫we're calling it in Begin Play and then we need to actually set the location so we can get that from

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‫the line of code, getting our player -- first and foremost.

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‫So uncomment that and then we want to do the player pawn arrow and get actor location like so and finish

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‫off the line with the semicolon.

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‫And it's as simple as that to go ahead and set a blackboard value.

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‫So your challenge is going to be to do the other half of this, which is to create a key in the blackboard.

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‫So add the key to the blackboard, make sure it's of the right type, the right name, and then if everything

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‫worked correctly, you should be able to check that value at runtime.

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‫Remember last lecture?

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‫We saw how we can see the behavior tree.

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‫You can do the same thing.

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‫You can inspect the blackboard at runtime when you're playing and you should be able to see what value

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‫was set by the C++ code.

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‫Pause the video and have a go.

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‫Okay.

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‫Welcome back.

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‫So I'm going to go over in to the editor hit compile because I haven't done that already.

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‫And we're going to add a new blackboard key.

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‫And in this case, we have to get the names right and the types right, otherwise things will go wrong.

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‫So we've got a vector key which we're going to be calling our player location, and I'm going to copy

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‫that to make sure that we have got the right spelling here.

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‫Yes, we have cool beans.

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‫And then what we're going to do is we're going to head over and just check that the blackboard details

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‫are okay.

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‫So yeah, there's a name you could add a description if you wanted.

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‫The type is a vector.

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‫That's cool.

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‫For instance, select.

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‫This is a variable that we're not particularly interested in at the moment.

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‫Cool.

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‫We've got our code has compiled, so let's go and hit play and see whether we can inspect that blackboard

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‫value.

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‫Go over to the blackboard and you can see we can still have that dropdown of choosing which I, we want

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‫this to relate to.

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‫We've only got one in our world, but you can see that self actor hasn't been set, but the player's

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‫location has indeed been set.

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‫Let's check if that is roughly correct.

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‫If I f h d possess, have a look at my player and have a look at the player's location.

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‫You can see that.

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‫Yes, it's pretty much correct.

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‫2000 -5100.

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‫2000 -5100.

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‫So that's setting the value through from C++.

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‫Simple as that.

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‫We can start to see how we can interface with our behavior trees.

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‫In the next lecture, we're going to look at the actual structure of behavior trees and making them

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‫do something.

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‫The exciting part.

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‫See you there.