WEBVTT 00:06.850 --> 00:07.900 Welcome back. 00:07.990 --> 00:11.610 So one of our next steps is to create an AI controller. 00:11.620 --> 00:20.500 And if we go into our character folder and open up enemy base, we can search for AI controller as the 00:20.500 --> 00:24.190 character class has an AI controller class. 00:24.190 --> 00:32.140 So if it has an AI controller set for its AI controller class, then it's going to use that for AI. 00:32.170 --> 00:39.430 But we're going to want our own custom AI controller class so we can add behavior tree and blackboard 00:39.430 --> 00:40.750 components to it. 00:41.360 --> 00:48.560 So for this reason, we're going to go into C plus plus classes or public, and I'd like a new folder 00:48.560 --> 00:51.620 specifically for AI related classes. 00:51.620 --> 00:57.140 So I'm going to make a new class here, choose all classes and search for AI controller. 00:57.140 --> 00:59.210 So we have the AI controller class. 00:59.210 --> 01:08.420 We're going to choose that and put this in a new folder called AI, and this is going to be Ora AI controller. 01:08.450 --> 01:13.580 Let's create the class I'm going to click on No and close the editor. 01:13.970 --> 01:19.910 I'm going to go ahead and close all tabs here and go into my new AI folder. 01:20.610 --> 01:22.090 And there it is. 01:22.110 --> 01:27.630 Here's my aura controller and I can open the CPP file as well. 01:27.840 --> 01:31.890 Now, aura controller is going to be relatively simple. 01:31.890 --> 01:33.990 It just needs a couple of components. 01:34.020 --> 01:37.520 A blackboard component and a behavior tree component. 01:37.530 --> 01:40.290 And we'll learn what these things are and how they work. 01:40.290 --> 01:43.500 But first we're going to add these to our controller. 01:43.500 --> 01:51.000 And before we do, we're about to use some classes that exist in an AI module in Unreal Engine. 01:51.000 --> 01:57.960 So we have to go to Aura Build X and we need to add something to our dependencies here. 01:57.960 --> 02:01.740 So I'm going to add two private dependency module names. 02:04.600 --> 02:07.720 I module, that's what it's called. 02:07.720 --> 02:09.160 It needs to go into quotes. 02:09.160 --> 02:16.780 So I module is going to contain those I related classes that we're going to want to use. 02:16.930 --> 02:23.950 Now that I have that, I'm going to go ahead and close out of the build file and we're going to add 02:23.950 --> 02:25.320 these components here. 02:25.330 --> 02:33.880 So I need a public section and I'm going to construct these components in the I controllers constructor. 02:33.880 --> 02:40.690 So we're going to have a constructor here and the blackboard and behavior tree components can be protected. 02:42.090 --> 02:44.650 So we'll have a couple of T object pointers. 02:44.670 --> 02:50.160 Now, the types for these two components I'm going to forward declare up at the top. 02:50.340 --> 02:58.140 So the first one is going to be you blackboard component and the next one will be you behavior tree 02:58.170 --> 02:59.130 component. 02:59.400 --> 03:01.770 These are the types of components we need. 03:01.860 --> 03:06.960 So first we'll make a T object pointer of type u blackboard component. 03:06.990 --> 03:09.900 This will be called blackboard component. 03:11.250 --> 03:13.050 We'll give this a property. 03:14.410 --> 03:20.770 And we can add a t object pointer of type you behavior tree component. 03:20.770 --> 03:24.100 And this will be behavior tree. 03:24.930 --> 03:28.950 Component and this also gets a new property. 03:30.040 --> 03:35.500 So now that we have these, we just need to construct them in the constructor, which means we should 03:35.500 --> 03:37.450 generate a definition for it. 03:37.570 --> 03:39.350 The constructor, that is. 03:39.370 --> 03:42.740 So we need to construct these components. 03:42.760 --> 03:46.930 We need to construct blackboard component and behavior tree component. 03:46.960 --> 03:49.330 So we'll start with Blackboard component. 03:49.360 --> 03:55.900 We're going to use Create Default Subobject with you Blackboard component. 03:56.800 --> 04:03.700 Thanks to writer for including my header file and we'll call this blackboard component. 04:05.310 --> 04:08.250 Next we can create the behavior tree component. 04:10.110 --> 04:18.030 So we'll use create default subobject with you behavior tree components and we'll call this behavior 04:18.030 --> 04:20.060 tree component. 04:20.070 --> 04:24.120 And again, thanks to writer I have my includes. 04:24.480 --> 04:25.710 Now we can check these. 04:25.710 --> 04:28.250 These should definitely be valid by this point. 04:28.260 --> 04:30.300 So we're going to make sure of that. 04:30.450 --> 04:36.660 We'll check Blackboard component and we'll check behavior tree component. 04:36.900 --> 04:38.040 And there we go. 04:38.220 --> 04:46.200 So now that we have our components on the AI controller class, our enemy needs to have a behavior tree 04:46.230 --> 04:49.920 that it can use by our behavior tree component. 04:49.950 --> 04:56.190 So we're going to go to Ora Enemy, and here in the protected section, we're going to add a behavior 04:56.190 --> 04:56.550 tree. 04:56.550 --> 04:59.190 But I'd like to forward declare this type. 04:59.850 --> 05:03.000 So I'm going to forward declare you behavior tree. 05:05.110 --> 05:10.230 I'd also like a pointer to our AI controller, which I'm also going to forward declare. 05:10.240 --> 05:13.370 So I'm going to forward declare ora AI controller. 05:13.390 --> 05:14.110 Be careful. 05:14.110 --> 05:15.640 There's an A at the beginning. 05:15.640 --> 05:17.200 It's an actor after all. 05:17.200 --> 05:19.720 So we have a ora AI controller. 05:19.750 --> 05:25.120 We're going to add a couple of pointers, one for the behavior tree and one for the AI controller. 05:25.240 --> 05:26.920 So first, the behavior tree. 05:26.920 --> 05:33.880 We're going to have a T object pointer of type U behavior tree and we'll call this behavior tree. 05:34.090 --> 05:38.200 And this gets a U property and we're going to be setting this from the blueprint. 05:38.200 --> 05:44.350 So it's going to be edit anywhere or edit defaults only and we'll give it a category of AI. 05:46.510 --> 05:50.200 Now we'll also have a pointer to our AI controller. 05:51.230 --> 05:55.100 And this will be of type A ora i controller. 05:56.410 --> 05:59.290 And we'll call this aura AI controller. 06:01.450 --> 06:03.280 And this simply gets a new property. 06:03.280 --> 06:05.200 We're not going to expose it to blueprint. 06:06.550 --> 06:08.110 At least for the time being. 06:08.140 --> 06:08.530 Okay. 06:08.530 --> 06:16.630 So we can set that from our blueprint or AI controller, however, needs to be set at some point and 06:16.630 --> 06:23.440 the soonest we know we have a valid controller that we can cast to this and set this pointer is in possessed 06:23.440 --> 06:26.500 by so we can override possessed by. 06:26.500 --> 06:28.270 We've seen this function before. 06:28.420 --> 06:32.860 We're going to have a virtual void possessed by that's an override. 06:32.860 --> 06:35.740 We're going to go ahead and generate a definition for this. 06:35.740 --> 06:45.520 We'll let this call super, but then we're going to set our AI controller equal to a cast to or AI controller 06:45.550 --> 06:48.130 A or AI controller to be exact. 06:48.130 --> 06:53.710 And we're going to cast the new controller that we have access to here in possessed by. 06:53.860 --> 06:56.920 So at this point we'll have our AI controller. 06:56.950 --> 07:03.600 Now notice at the top we now have or AI controller here, so that is included. 07:03.610 --> 07:08.060 So now that we have some variables, it's time to go back into blueprint. 07:08.090 --> 07:14.720 We need to make sure our enemy is using our custom AI controller as well as the behavior tree that we 07:14.720 --> 07:16.160 are going to create. 07:16.190 --> 07:19.820 So let's go ahead and compile and launch the editor. 07:21.310 --> 07:26.110 So with the editor open, we know that we have a new AI controller class. 07:26.200 --> 07:33.280 I'd like to go to Blueprints and make a new folder here for all AI related blueprints. 07:33.490 --> 07:38.590 And here in AI, I'm going to make my new AI controller blueprint. 07:38.620 --> 07:45.190 I'm going to create a new Blueprint class and search for Aura AI and get my aura AI controller select 07:45.190 --> 07:49.570 that and make a BP aura AI controller. 07:49.660 --> 07:52.000 So at least we have a blueprint here. 07:52.090 --> 07:53.830 Here's what it looks like. 07:53.860 --> 08:00.070 Nothing really that we need to set on it, but we know that it's an AI controller and this is our AI 08:00.100 --> 08:04.030 controller class that we want to use on our enemies. 08:04.030 --> 08:09.790 So we're going to go to blueprints and character and here's BP enemy base. 08:09.820 --> 08:17.110 We need to search for AI controller class and this is not our aura AI controller. 08:17.110 --> 08:19.120 We didn't expose that to blueprint. 08:19.150 --> 08:21.170 We're setting that in C plus plus. 08:21.170 --> 08:25.760 This is the character inherited AI controller class. 08:25.790 --> 08:28.370 It sets an AI controller by default. 08:28.400 --> 08:34.910 We'd like to use our BP aura AI controller, and that way it'll be controlled by that. 08:35.030 --> 08:42.560 Now at the same time, we also have under our category AI a behavior tree. 08:42.590 --> 08:44.810 Now there's nothing to set it to. 08:44.840 --> 08:48.380 We haven't created a behavior tree or a blackboard. 08:48.380 --> 08:54.020 And again, we'll get into exactly what these classes are and what they can do for us once it's time 08:54.020 --> 08:55.190 to get into that. 08:55.280 --> 09:00.950 But for now, we're just going to create these classes a behavior tree and a blackboard, and those 09:00.950 --> 09:02.300 can go in blueprints. 09:02.330 --> 09:11.120 AI So for a blackboard, we're going to right click go to Artificial Intelligence and select Blackboard. 09:11.120 --> 09:17.390 And this can be prefixed with B for Blackboard, and we're going to call this enemy Blackboard. 09:17.780 --> 09:20.660 We're also going to create an enemy behavior tree. 09:20.660 --> 09:24.560 So right click artificial intelligence and Behavior Tree. 09:24.560 --> 09:31.670 We're going to call this BT for Behavior tree and call it enemy behavior tree. 09:32.090 --> 09:34.370 Now we can double click these to open them up. 09:34.370 --> 09:35.990 Here's the behavior tree. 09:35.990 --> 09:37.550 It has a root node. 09:37.550 --> 09:43.460 We're going to learn about how to use this, but it also has a behavior tree and a blackboard tab. 09:43.460 --> 09:47.720 So here's the blackboard associated with this behavior tree. 09:47.810 --> 09:54.470 So now that we have a behavior tree asset called enemy Behavior tree, we can go back to enemy base. 09:54.470 --> 09:57.110 Here's our enemy behavior tree variable. 09:57.110 --> 10:01.040 We can now set it to BT Enemy behavior tree. 10:01.040 --> 10:04.460 And now that behavior tree variable has been set. 10:04.610 --> 10:11.630 So after doing all this, now that these classes actually exist, we have a behavior tree in a blackboard. 10:11.630 --> 10:13.760 We have to run the behavior tree. 10:13.760 --> 10:18.320 We have to set it in motion so that it's actively controlling our character. 10:18.320 --> 10:21.650 And to do that, we go back into C plus plus. 10:21.650 --> 10:25.280 So we're going to close and save everything that we've changed here. 10:25.520 --> 10:29.210 So here in C plus plus, we need to run the behavior tree. 10:29.240 --> 10:33.140 Now, a behavior tree is always associated with a given blackboard. 10:33.140 --> 10:37.670 As we saw, there was a blackboard tab in the behavior tree asset. 10:37.700 --> 10:40.130 We're going to make that association as well. 10:40.130 --> 10:45.350 We're going to do all this from the aura enemy here in possessed by because this is the perfect place 10:45.350 --> 10:45.920 to do it. 10:45.920 --> 10:48.620 Now we're going to check if we have authority. 10:48.620 --> 10:52.790 In fact, we're going to say if not has authority, we're going to return. 10:52.790 --> 10:53.270 Why? 10:53.300 --> 10:56.240 Because I only matters on the server. 10:56.480 --> 10:58.790 AI characters are controlled on the server. 10:58.790 --> 11:02.510 Anything that clients see is the result of replication. 11:02.510 --> 11:05.780 So we're only setting AI controller on the server. 11:05.780 --> 11:13.040 And if we check this pointer for validity and it's null, we know that we're not on the server and so 11:13.040 --> 11:13.510 on. 11:13.520 --> 11:16.070 Now we want to run the behavior tree. 11:16.070 --> 11:17.030 That's pretty easy. 11:17.030 --> 11:25.610 We take our aura AI controller and AI controllers and it would help if I spelled it without typos. 11:25.610 --> 11:26.390 There we go. 11:26.690 --> 11:33.320 And AI controllers have run behavior tree, which takes a pointer to a behavior tree. 11:33.470 --> 11:36.650 Now we have one, so we're going to pass that in. 11:37.370 --> 11:39.920 Now, that's not the only thing we should do. 11:39.950 --> 11:45.860 We should also initialize the blackboard on the blackboard component. 11:45.890 --> 11:52.610 So whatever blackboard is associated with our behavior tree asset, our AI controller needs to take 11:52.610 --> 11:57.770 its blackboard component and initialize it with that blackboard asset. 11:58.520 --> 12:05.990 So the AI controller class has a getter for its blackboard component so we can take our aura AI controller 12:06.110 --> 12:09.650 and we can call get blackboard component. 12:09.650 --> 12:13.100 And on this we can call initialize. 12:14.110 --> 12:14.960 Blackboard. 12:14.980 --> 12:17.680 Now, this requires a new blackboard. 12:17.680 --> 12:18.520 Data. 12:18.550 --> 12:20.470 Our behavior tree has one of these. 12:20.470 --> 12:25.660 If we take our behavior tree, we can access the blackboard asset. 12:25.690 --> 12:28.210 Now, this is a new blackboard data. 12:28.210 --> 12:31.660 It's a T object pointer as we see. 12:31.660 --> 12:36.810 So we're going to have to dereference this pointer and pass it in as a non pointer. 12:36.820 --> 12:40.900 Now the AI controller class has this git blackboard component, right? 12:40.900 --> 12:47.260 And if we go to its definition, we see that it simply returns Blackboard. 12:47.290 --> 12:53.710 This is a U blackboard component pointer that exists on the AI controller. 12:54.380 --> 12:57.590 So really this means that we could just set this. 12:57.620 --> 12:58.670 It's protected. 12:58.700 --> 13:03.200 We don't really need to create a blackboard component variable. 13:03.200 --> 13:07.970 When we create our blackboard component, we can really just set blackboard, right? 13:07.970 --> 13:16.030 So we could just go back to our AI controller and remove blackboard component altogether and in or AI 13:16.070 --> 13:24.620 controller cpp, we could really just set the blackboard to the result of create default Subobject here 13:24.800 --> 13:26.830 and check blackboard. 13:26.840 --> 13:32.620 So really no need to create blackboard component if Blackboard is already a variable. 13:32.630 --> 13:38.360 Now in Ora Enemy, we know that we're accessing the blackboard component that we've created and we're 13:38.360 --> 13:39.710 initializing it. 13:40.310 --> 13:47.810 So now after all this, we know that we'll be running our behavior tree as long as our enemies have 13:47.810 --> 13:52.670 their behavior tree variable set and we set that on the base enemy class. 13:52.670 --> 13:56.970 So let's just go ahead and compile and launch the editor. 13:57.820 --> 14:00.690 And I'm going to go ahead and open up my behavior tree. 14:00.700 --> 14:07.150 And the last thing we can do is just make sure that our enemies have their behavior trees running. 14:07.180 --> 14:11.210 So we'll get into what the nodes in the behavior tree can do. 14:11.230 --> 14:16.990 But for now, we're just going to do a quick test to make sure it's working by dragging off of the root 14:16.990 --> 14:18.800 and adding a selector. 14:18.820 --> 14:26.920 And from the selector, we're going to drag off, expand tasks and we're going to choose a play animation 14:26.920 --> 14:27.820 task. 14:27.850 --> 14:32.600 Now, with the play animation task selected, here's animation to play. 14:32.620 --> 14:35.200 We're going to choose to play an animation. 14:35.800 --> 14:37.890 I'm going to choose Attack Spear. 14:37.900 --> 14:44.000 So this is just a quick test to see if our behavior tree is running on our enemies. 14:44.020 --> 14:45.400 We're going to press play. 14:46.170 --> 14:51.840 We're going to run up to our enemies and they're playing the attack spear animation. 14:51.840 --> 14:54.690 So that proves that our behavior tree is running. 14:54.690 --> 15:01.860 And if we undock it and take a look at those nodes in the tree and press play, we'll see that suddenly 15:01.860 --> 15:03.210 it looks a little bit different, right? 15:03.210 --> 15:05.220 We're seeing this flow here. 15:05.400 --> 15:10.200 We are able to see where in the tree we are. 15:11.290 --> 15:12.690 So that's pretty nice. 15:12.700 --> 15:16.780 So we know that the tree is working, Everything is tied together. 15:17.620 --> 15:19.060 This is a great start. 15:19.090 --> 15:21.520 We're ready to start fleshing out our tree. 15:21.550 --> 15:23.320 We can go ahead and remove those nodes. 15:23.320 --> 15:28.200 We'll get into the details of what to do in this tree soon enough. 15:28.210 --> 15:36.460 But now that everything is working, we're going to save all and we're ready to start giving our enemies 15:36.460 --> 15:38.260 some AI behavior. 15:38.470 --> 15:41.320 Great job and I'll see you in the next video.