WEBVTT 00:06.850 --> 00:08.050 Welcome back. 00:08.080 --> 00:12.760 Now, we've seen that we can use a number of built in behavior tree tasks. 00:12.760 --> 00:13.990 And these are really handy. 00:13.990 --> 00:21.730 We have common ones ones to make the AI character wait make them move to a specific location, or really 00:21.730 --> 00:28.210 any blackboard key that has a location in space, whether that's an actor, a character, or what have 00:28.210 --> 00:28.570 you. 00:28.570 --> 00:35.260 Now, these built in tasks are nice, but we don't really have any built in tasks for exactly the things 00:35.260 --> 00:35.680 we need. 00:35.680 --> 00:41.920 In every case, I don't have a built in behavior tree task called attack, for example. 00:41.920 --> 00:44.230 Now for combat we need to attack. 00:44.230 --> 00:48.730 So we're going to need our own behavior tree task and we can create our own. 00:48.730 --> 00:51.070 Hey there Steven from the future here. 00:51.070 --> 00:58.090 And I'm just coming back to let you know that in the original version of the course, we created a behavior 00:58.090 --> 01:04.180 tree task in C plus plus based on Behavior Tree task blueprint base. 01:04.180 --> 01:10.930 Basically doing the same wrong thing as when I created the behavior tree service. 01:10.930 --> 01:17.290 So the GitHub commit for this lecture has a C plus plus class that you can ignore. 01:17.290 --> 01:21.280 We're just going to create the blueprint for the behavior tree task. 01:21.280 --> 01:26.530 In this video you can safely ignore the GitHub commit with the C plus plus class. 01:26.530 --> 01:32.950 We're going to do things the right way in this updated version with the blueprint, I'm going to open 01:32.950 --> 01:34.390 up my behavior tree. 01:34.390 --> 01:41.380 And we know that we're reserving this branch for ranged attackers and this branch for melee attackers. 01:41.380 --> 01:43.870 And our behavior tree knows which one is which. 01:43.870 --> 01:52.330 It knows which one it's controlled pawn is because it has a ranged attacker boolean blackboard key. 01:52.330 --> 01:58.450 And we're setting that from the enemy as soon as it's or I controller variable is set and that's an 01:58.450 --> 01:59.290 on possess. 01:59.290 --> 02:03.670 So quite early on it knows whether it's a ranged attack or not. 02:03.670 --> 02:06.880 We're going to handle the melee attacker situation first. 02:06.880 --> 02:11.080 And we're going to want to create a blueprint based on our behavior tree task. 02:11.080 --> 02:21.640 So we're going to right click create a new blueprint class, search for BT task and get BT Task Blueprint 02:21.640 --> 02:22.420 Base. 02:22.420 --> 02:26.680 We'll select that and we're going to call this BT. 02:28.400 --> 02:33.050 Attack and we have our blueprint, task, attack. 02:33.050 --> 02:39.860 And of course we can override functions such as receive, execute I so we can receive that. 02:39.860 --> 02:46.520 And the most important thing that we have to be concerned with here is that we finish execute so that 02:46.520 --> 02:50.480 our behavior tree doesn't get hung up on this task. 02:50.480 --> 02:53.240 The task has to return success or failure. 02:53.240 --> 02:58.730 And before we return that success or failure, we'll be stuck inside this task. 02:58.730 --> 03:02.360 So the way to return that is to use finish, execute. 03:02.570 --> 03:05.000 And this returns success or failure. 03:05.000 --> 03:06.110 I'm going to check that. 03:06.110 --> 03:08.690 So it returns success by default. 03:08.690 --> 03:12.950 And we're going to go ahead and just drag in the execution pin here. 03:13.070 --> 03:15.560 So our task does nothing. 03:15.560 --> 03:18.140 But we're going to do things with it definitely. 03:18.140 --> 03:25.610 For now though, let's go back to our behavior tree and drag off of our sequence and expand tasks. 03:25.610 --> 03:27.740 And there's our BT attack. 03:27.740 --> 03:31.400 So let's use our blueprint BT attack. 03:31.400 --> 03:32.360 And there it is. 03:32.390 --> 03:36.050 And if we click on it we see that it has a details panel. 03:36.050 --> 03:38.060 We can rename the node here. 03:38.060 --> 03:43.940 And of course we have nothing really else unless we go in here and add things. 03:43.940 --> 03:45.830 Now we have the owner controller. 03:45.830 --> 03:48.080 We also have controlled pawn. 03:48.080 --> 03:53.630 Now I'm going to drag off of the controlled pawn and use get object name. 03:56.860 --> 03:59.950 And we're going to print the name of this controlled pawn. 03:59.950 --> 04:01.330 So print string. 04:01.840 --> 04:04.750 We're going to run that in and finish execute. 04:04.750 --> 04:08.620 Let's just see what that controlled pawn is. 04:09.930 --> 04:15.750 So if we're close enough to attack, we should see that BT task attack. 04:15.750 --> 04:17.310 Let's go ahead and press play. 04:17.310 --> 04:18.930 Here come our enemies. 04:18.930 --> 04:21.720 Let's see if we get anything printed to the screen. 04:21.720 --> 04:29.280 And here we see BP Goblin spear were basically spamming the window with those messages. 04:29.610 --> 04:36.180 So as long as the enemy is close enough to attack and it's a melee attacker, we're getting some messages 04:36.180 --> 04:40.320 and we know that the controlled pawn is set to that actual pawn. 04:40.320 --> 04:43.140 Let's change this to owner controller. 04:45.080 --> 04:48.170 And just see what we get printed to the screen in this case. 04:49.980 --> 04:54.270 And as soon as they're close, we see our AI controller. 04:54.270 --> 05:00.630 So we know that in Bot Attack, we have access to the pawn and the controller here in event receive 05:00.630 --> 05:01.680 execute AI. 05:01.680 --> 05:02.820 And that's looking good. 05:02.820 --> 05:09.750 So now that we have a behavior tree task for attacking, let's show something visual here in the world. 05:09.750 --> 05:13.590 Say we'll draw a debug sphere in the place of the enemy. 05:13.590 --> 05:15.720 So in the place of our controlled pawn. 05:15.840 --> 05:20.550 So I'm going to delete those nodes and do a draw debug sphere. 05:23.170 --> 05:26.050 The center will be at our controlled pawns location. 05:26.050 --> 05:28.240 So I'm going to use get actor location. 05:29.580 --> 05:33.990 Drag that in for the center and we'll make the line color red. 05:35.370 --> 05:38.670 Will make the duration three seconds. 05:38.700 --> 05:41.490 The radius can be 40. 05:42.030 --> 05:44.250 And we'll go ahead and hook this up to finish. 05:44.250 --> 05:45.360 Execute. 05:45.360 --> 05:48.480 And let's get those debug spheres. 05:49.080 --> 05:50.130 There they are. 05:56.100 --> 06:00.300 So now we have some visual feedback that will tell us when we're attacking. 06:00.860 --> 06:08.000 Now if we're close enough to attack, which is a distance of less than 500, I'm going to want a little 06:08.000 --> 06:13.400 bit more sophisticated AI behavior than just execute this attack. 06:13.400 --> 06:19.040 So far, attack does nothing but draw a debug sphere, but we're going to make a gameplay ability to 06:19.040 --> 06:20.300 execute for that. 06:20.300 --> 06:26.780 But until then, I'd like our enemy to get close enough to quote and unquote attack. 06:26.780 --> 06:33.920 And what that means is I'd like our enemy to move in closer, because 500 is not that far, really. 06:33.920 --> 06:40.040 These enemies are coming in close because we're not aborting this other move to target here. 06:40.040 --> 06:46.070 You see, if I'm far enough to approach, we're seeing if the distance is greater than or equal to 500. 06:46.190 --> 06:53.690 If we were to abort this branch, as soon as this is no longer the case, then we should not reach closer 06:53.690 --> 06:54.650 than 500. 06:54.650 --> 06:55.670 So we can take this. 06:55.670 --> 06:59.780 Am I far enough to approach and set this to abort? 06:59.780 --> 07:08.330 Self, for example, and notice that this entire thing, this entire branch has green and it says nodes 07:08.330 --> 07:10.190 aborted by mode itself. 07:10.190 --> 07:15.980 And that's because if we abort this self branch, then whatever tasks are running here, those will 07:15.980 --> 07:19.730 be aborted and we'll return back up the tree. 07:19.730 --> 07:22.460 So if I go ahead and press play now. 07:24.080 --> 07:25.280 And let these guys run. 07:25.280 --> 07:28.550 You see that they stop 500 units away. 07:28.640 --> 07:30.980 So I think that's what I'd like. 07:30.980 --> 07:36.470 I'd like this to only handle running up to 500 units away. 07:36.470 --> 07:42.740 And once we're close enough to attack here, then I'd like our melee attackers to move in. 07:42.740 --> 07:44.750 We'll get to the ranged attackers later. 07:44.750 --> 07:49.610 They're going to hang back a little farther so they can launch their projectiles and such. 07:49.610 --> 07:52.790 But our melee attackers, they're going to move in close. 07:52.790 --> 07:56.180 So I'm going to drag out and use a move to task. 07:56.810 --> 07:58.100 Let's get our move two. 07:58.130 --> 08:00.590 We're going to move to our target to follow. 08:00.590 --> 08:03.830 So we're going to set the blackboard key here to target to follow. 08:04.130 --> 08:08.600 This is going to have an acceptance radius five is a little bit close. 08:08.600 --> 08:10.460 So I'm going to bring it up to about 20. 08:10.460 --> 08:14.330 And we can rename this node by changing the node name. 08:14.330 --> 08:16.220 We can call this get close. 08:16.220 --> 08:19.400 So this task gets us in a little closer. 08:19.400 --> 08:21.920 And then we'll execute it attack. 08:21.920 --> 08:27.140 And with BT attack selected I'm going to actually rename this node to just attack. 08:27.140 --> 08:34.340 So being able to rename the nodes like this can really make our behavior tree a lot more easy to read 08:34.340 --> 08:35.420 at first glance. 08:35.420 --> 08:38.120 So now our melee attackers are going to get closer. 08:38.120 --> 08:39.740 Let's see how this works. 08:40.600 --> 08:41.800 Here they come. 08:42.370 --> 08:43.330 And look at that. 08:43.330 --> 08:45.520 Our melee attackers are getting close. 08:46.870 --> 08:48.280 Those two back there. 08:48.310 --> 08:50.080 They are ranged attackers. 08:50.080 --> 08:53.020 So our melee attacker came in close. 08:53.020 --> 08:55.840 The ranged attackers stayed back a bit. 08:55.870 --> 09:00.130 Now if that distance gets farther than what was it, 4000? 09:00.130 --> 09:01.000 Something like that. 09:01.000 --> 09:03.670 Well then our ranged attackers stay in. 09:03.670 --> 09:04.960 The melee attacker comes. 09:04.960 --> 09:05.470 Now. 09:05.470 --> 09:12.820 If they get in each other's way, they don't create holes in the navmesh, so they're not going to create 09:12.820 --> 09:14.650 path points around each other. 09:14.650 --> 09:22.450 If I press P to show our nav mesh bounds volume, notice that these little guys are not making holes 09:22.450 --> 09:23.410 in the nav mesh. 09:23.410 --> 09:31.090 So if these two form a wall and this guy tries to move through it, it's not going to be smart enough 09:31.090 --> 09:32.530 to avoid them. 09:32.890 --> 09:39.760 There are ways to have them avoid each other, but by default the way it is now, they're not going 09:39.760 --> 09:40.720 to avoid each other. 09:40.720 --> 09:47.230 But for now, it's enough that our ranged attackers hang back and our melee attacker comes in, and 09:47.230 --> 09:51.010 when it gets close enough, it hits that acceptance radius. 09:51.010 --> 09:51.790 It attacks. 09:51.790 --> 09:55.000 And we know because we see that red sphere. 09:55.390 --> 09:58.330 So that is a good stopping point. 09:58.330 --> 10:04.210 I think we are one step closer to having our AI behave as they should. 10:04.210 --> 10:06.550 We're taking care of our ranged attackers. 10:06.550 --> 10:13.150 They just hang back and our melee attackers, they decide to get close and they attack. 10:13.600 --> 10:20.560 Now after our attack, we're going to want to decide what to do there and we'll handle that next. 10:20.560 --> 10:25.270 And of course, we're going to need to actually make these little guys attack. 10:25.270 --> 10:30.910 So we have a few steps left to go and we'll continue with this in the videos to come. 10:30.910 --> 10:33.340 So great job and I'll see you soon.