WEBVTT 00:06.960 --> 00:08.100 Welcome back. 00:08.130 --> 00:10.410 So now we have our enemies. 00:10.440 --> 00:15.570 They're doing something, but we definitely want them to do more, Right? 00:15.570 --> 00:22.660 So we're going to continue and I'm going to start by opening up my behavior tree. 00:22.680 --> 00:28.380 So I'm going to go to blueprints I and open my enemy behavior tree here. 00:28.590 --> 00:36.510 Now we have a service find nearest player and it's setting the values of a couple of our blackboard 00:36.510 --> 00:38.760 keys every half second or so. 00:39.090 --> 00:45.150 And we can use those blackboard key values to determine what we should do next. 00:45.360 --> 00:49.540 Now, what I'd like to do is start using some decorators. 00:49.560 --> 00:57.120 Decorators can also be attached to nodes and they can provide us with conditions. 00:57.120 --> 01:05.370 Kind of like if statements that can allow us to execute a given branch or prevent the execution of a 01:05.370 --> 01:08.290 given branch, depending on those conditions. 01:08.560 --> 01:14.920 So I'm going to get rid of this move to Node, just highlight it and delete it and I'd like another 01:14.920 --> 01:15.580 selector. 01:15.580 --> 01:24.490 So I'm going to drag off, search for selector and add one and I can add a decorator to this selector 01:24.490 --> 01:29.620 by right clicking add decorator and choosing blackboard. 01:30.120 --> 01:36.810 Now I have this blue thing connected to my selector that says blackboard based condition, and we can 01:36.810 --> 01:41.190 prevent going into this selector based on a condition. 01:41.220 --> 01:43.740 The condition is based on a blackboard key. 01:43.740 --> 01:48.390 And if we choose that key under blackboard key, we can set it to something. 01:48.630 --> 01:51.480 I'd like to set it to target to follow. 01:51.660 --> 01:56.040 And key query can be is set or is not set. 01:56.070 --> 02:03.120 If it's set to is set, then target to follow must be set in order for us to execute this selector. 02:03.120 --> 02:10.590 So if I have children hooked up to the selector, then they will only be executed if target to follow 02:10.590 --> 02:11.430 is set. 02:11.460 --> 02:19.980 Now notify Observer says that when the result of this evaluation checking target to follow, if that 02:19.980 --> 02:26.430 is changed when we're evaluating it, then we will not enter this selector. 02:26.460 --> 02:31.000 We will fail and return failure back up to the parent. 02:31.470 --> 02:35.220 Now we could change notify observer to on value change. 02:35.220 --> 02:41.700 And that means if we've already made it past this decorator at some point, if target to follow becomes 02:41.700 --> 02:45.810 unset, then this node could abort itself. 02:45.810 --> 02:53.370 Depending on the observer aborts selection, it could abort the self, it could abort only lower priority 02:53.400 --> 02:55.770 nodes and nodes have priority. 02:55.770 --> 03:02.850 We can see them with these little numbers connected to each node and it can abort both, but we're going 03:02.850 --> 03:08.580 to set it to none and leave this on set to on result change for notify observer. 03:08.580 --> 03:17.070 All I care about is preventing the execution of the selector if target to follow is not set and if we 03:17.070 --> 03:20.220 make it past this first selector, it should be set. 03:20.250 --> 03:23.550 That's why I'm checking it after this selector. 03:23.550 --> 03:30.330 If I attach this decorator to this selector up here, then we would never get to set it because it would 03:30.330 --> 03:37.210 never be set in the first place and the decorator would prevent this service from being run. 03:37.240 --> 03:45.400 So we have a decorator that checks to make sure we have a target to follow, and then it can execute 03:45.400 --> 03:47.410 its children left to right. 03:47.560 --> 03:51.160 Now, I'd like to also check another condition. 03:51.160 --> 03:54.130 I'd like to see if our enemy is hit reacting. 03:54.130 --> 03:57.640 Now, that's not a blackboard key, but we can easily add one. 03:57.640 --> 04:05.080 Let's go to our blackboard and add a new key of type bool and this one can be hit reacting. 04:05.350 --> 04:08.140 So we have this blackboard key hit reacting. 04:08.140 --> 04:11.410 Now this should be false by default. 04:11.440 --> 04:15.930 We want to set it to true when hit reacting and false when we're not. 04:15.940 --> 04:17.890 So how can we do that? 04:18.070 --> 04:25.330 Well, we can do this from C plus plus if we can get a hold of the aura AI controller which has access 04:25.330 --> 04:30.610 to the blackboard component blackboard components can set their blackboard values. 04:31.050 --> 04:39.060 So I'm going to close the editor and save and I'm going to open up my character folder and open Aura 04:39.060 --> 04:42.480 Enemy, and I'll get that header file open as well. 04:42.510 --> 04:45.540 Now we have our Aura AI controller here. 04:45.630 --> 04:50.160 As soon as we have this set, I'd like to set the blackboard value of that hit. 04:50.160 --> 04:55.830 Reacting key to false just so we make sure that it's set explicitly. 04:56.130 --> 05:00.240 So I'm going to search in the CPP file for aura AI controller. 05:00.240 --> 05:05.730 We're setting it here in possessed by and after we run the behavior tree, we can get our blackboard 05:05.730 --> 05:06.720 component from it. 05:06.750 --> 05:12.930 We're going to say Aura AI controller, get blackboard component and from the blackboard component we 05:12.930 --> 05:20.340 can set a value as boolean by calling the function set value as bool. 05:20.550 --> 05:23.610 It takes a name and it's called key name. 05:23.640 --> 05:27.780 We're going to pass in the name of hit reacting. 05:28.830 --> 05:31.050 And we're going to set this to false. 05:31.470 --> 05:35.220 And we also want to set this if we're hit, reacting. 05:35.220 --> 05:39.350 So we have a couple of callback functions for when we're hit reacting. 05:39.360 --> 05:41.490 If we scroll down, we'll see. 05:41.490 --> 05:43.710 We have hit react tag changed. 05:43.710 --> 05:51.300 So it's actually one callback and we're setting max walk speed based on be hit reacting we can also 05:51.300 --> 05:58.650 set that key so I'm going to control V and paste this line where we're setting value as bool and we're 05:58.650 --> 06:03.720 going to set hit, reacting equal to the value of be hit reacting. 06:03.720 --> 06:10.830 So every time we're hit, reacting or no longer hit reacting, we should be setting the blackboard key 06:10.860 --> 06:14.460 hit reacting so I can go ahead and hit the debug button. 06:15.670 --> 06:18.190 And we can get that blackboard back open. 06:18.190 --> 06:23.200 We can go into the behavior tree and we can check that hit Reacting Boolean. 06:23.290 --> 06:25.990 I'd like to add another decorator. 06:25.990 --> 06:30.160 So I'm going to right click add decorator, select Blackboard. 06:30.160 --> 06:35.590 And this second one is going to be checking our hit Reacting key. 06:35.590 --> 06:38.890 But this time key query should be is not set. 06:38.890 --> 06:43.930 I want to enter this branch if hit, reacting is not set. 06:43.930 --> 06:45.490 In other words, false. 06:45.540 --> 06:52.840 We're going to set that blackboard key to hit reacting Now I would like to abort the self if hit reacting 06:52.840 --> 06:54.010 becomes true. 06:54.010 --> 07:00.820 So for observer aborts, I'm going to set this to self and change notify observer to on value change. 07:00.820 --> 07:07.330 So any nodes that we have going on down here will stop if hit reacting becomes true. 07:07.360 --> 07:14.710 So now that we have a couple of decorators, we can start thinking about how we're going to make our 07:14.710 --> 07:23.720 enemy move toward the character and also attack the character, I'd like to have several different cases. 07:23.720 --> 07:26.900 I'd like to have a case for our ranged attackers. 07:26.900 --> 07:32.660 I'd like them to stop just short a little distance away before they start attacking. 07:32.780 --> 07:38.060 I'd like to have a separate case for non ranged attackers that want to get close. 07:38.090 --> 07:45.620 And in order to know that I need a blackboard key that can tell me if I have arranged attacker or not. 07:45.620 --> 07:54.440 So we're going to add one last blackboard key of type bool and this is going to be ranged attacker. 07:54.740 --> 08:02.480 And this we can also set from within C plus plus and we can check whether or not we have a ranged attacker 08:02.480 --> 08:03.890 from our selector. 08:03.890 --> 08:07.610 We can drag off and add more nodes. 08:07.610 --> 08:13.880 Now we have selectors up here, but we also have the option to make a sequence node, which is just 08:13.880 --> 08:17.090 like a selector only it has one key difference. 08:17.120 --> 08:22.100 A selector executes children from left to right until one of them succeeds. 08:22.130 --> 08:26.570 A sequence executes children from left to right until one of them fails. 08:26.570 --> 08:32.060 So I'm going to have a sequence here and I'm going to put a little comment here and say, for ranged 08:32.060 --> 08:34.430 attackers or just ranged attacker. 08:34.550 --> 08:38.120 So we'll have some nodes and some logic here. 08:38.120 --> 08:41.030 I'm going to have another sequence here. 08:41.030 --> 08:43.490 And this is going to be for melee attackers. 08:43.490 --> 08:51.200 So I'm going to comment this and say melee attacker, and we'll check first if we're arranged attacker. 08:51.230 --> 08:53.990 If not, we'll continue, Right. 08:53.990 --> 09:00.440 If this fails, we have a selector up here which will go from left to right until one of its children 09:00.440 --> 09:01.520 succeeds. 09:01.520 --> 09:02.840 So this will fail. 09:02.840 --> 09:09.500 So it will continue if this fails based on whatever decorators we put here, Perhaps the enemy isn't 09:09.500 --> 09:11.090 close enough to attack yet. 09:11.120 --> 09:14.330 Then we can have one last sequence over here. 09:14.720 --> 09:18.770 And this one is going to be for moving to the target. 09:18.770 --> 09:23.690 So this one, I'm going to have a comment that says Move to Target. 09:23.690 --> 09:27.980 And each of these will be able to fail based on whatever conditions we set. 09:28.310 --> 09:30.860 So we're going to flesh this out more. 09:30.860 --> 09:35.000 But first, I'd like my ranged attacker key to be set. 09:35.000 --> 09:37.130 So I'm going to set that from C plus plus. 09:37.130 --> 09:43.130 I'm going to go ahead and save the project and we'll go ahead and check our class to see if we're a 09:43.130 --> 09:45.110 ranged attacker or not. 09:45.110 --> 09:49.130 And we'll do that as soon as our AI controller is set. 09:49.430 --> 09:51.710 That's going to be here and possessed by. 09:52.160 --> 09:59.150 So I'm going to say if and we're going to check the character class, we're going to see if it's equal 09:59.150 --> 10:05.240 to a character class and our ranger is going to be a ranged attacker. 10:05.240 --> 10:12.650 But also our elementalist is going to have ranged attacks as well, think fireballs and things like 10:12.650 --> 10:13.310 that. 10:13.310 --> 10:16.850 So I'm going to consider both of these to be ranged attackers. 10:16.850 --> 10:19.640 So we'll really say, is it a warrior? 10:19.640 --> 10:21.590 In fact, we'll say is it not a warrior? 10:21.590 --> 10:24.980 Is character class not equal to warrior? 10:24.980 --> 10:27.350 If so, it's a ranged attacker. 10:27.500 --> 10:32.060 And we can call this line here set value as bool. 10:32.060 --> 10:34.190 In fact, we could just call it here. 10:34.220 --> 10:35.900 No need for an if statement. 10:35.930 --> 10:46.640 This right here character is not warrior is sufficient and the key is going to be ranged attacker. 10:48.800 --> 10:51.820 So we'll set ranged attacker equal to this value. 10:51.830 --> 10:56.870 If it's a warrior, ranged attacker will be false, otherwise it will be true. 10:56.990 --> 10:59.240 So we can go ahead and compile that. 11:01.020 --> 11:04.370 So these are very general blackboard keys. 11:04.380 --> 11:08.220 They're not specific to any one class. 11:08.250 --> 11:11.490 They're general across the board for the whole game. 11:11.490 --> 11:15.360 So I think it's okay to call them out directly in code like that. 11:15.450 --> 11:20.880 So we have our ranged attacker and I want to check that here for this one. 11:20.940 --> 11:29.790 I want to place a decorator here choosing Blackboard and selecting that The key query will be is set, 11:29.820 --> 11:35.520 the blackboard key will be is ranged attacker or just ranged attacker and we'll leave the rest at their 11:35.520 --> 11:36.300 defaults. 11:36.300 --> 11:41.550 So we'll only enter this sequence if we're arranged attacker. 11:42.240 --> 11:48.360 Now, if this branch fails, then this selector will just not execute it and it'll try the next one. 11:48.390 --> 11:53.580 The next one is going to check to see if we're within attack range. 11:53.670 --> 11:55.950 So let's add a decorator here. 11:55.950 --> 12:00.880 We'll choose Blackboard and this one will check our distance to Target. 12:00.960 --> 12:04.020 Now if we choose a float blackboard key. 12:04.050 --> 12:12.420 Now our key query is is equal to and a whole bunch of other options we're going to choose is less than. 12:13.160 --> 12:18.920 And we can have some kind of threshold, some close proximity value. 12:18.950 --> 12:20.930 We'll just use 500 for now. 12:20.930 --> 12:28.820 So if distance to target is less than 500, then we can get inside of this branch and then we can do 12:28.820 --> 12:30.140 our melee attack. 12:31.040 --> 12:32.840 So what if we fail that one? 12:32.840 --> 12:38.210 Well, if we're not arranged attacker and then we check and we're not within attack range. 12:38.210 --> 12:41.150 Well, that must mean we should be moving to the target. 12:41.150 --> 12:48.110 So in that case, we're going to move to the target so we can do a move to here. 12:48.110 --> 12:54.710 We can get the tasks and get moved to and move to our target to follow. 12:54.710 --> 13:00.740 So the blackboard key will be target to follow for this and we can give it a acceptance radius. 13:00.740 --> 13:02.450 I'll give it 50. 13:02.480 --> 13:03.980 So that's what we'll do. 13:03.980 --> 13:11.690 Now I'd like to have a little bit of a delay, not much, but a little bit of a hesitation before moving 13:11.720 --> 13:17.450 to the target so we can take our tasks and get a wait and select that and the wait time. 13:17.450 --> 13:21.440 I'd like to be zero plus or -0.5 seconds. 13:21.440 --> 13:27.680 So a random deviation of plus or -0.5 seconds before moving to the target. 13:27.710 --> 13:33.240 Now I only want to move to the target if we're close enough to approach. 13:33.240 --> 13:36.780 In other words, we're not super, super far away. 13:36.780 --> 13:38.940 So I'm going to add a decorator here. 13:39.120 --> 13:41.790 Decorator Blackboard. 13:41.790 --> 13:45.180 And for this I'm going to check my distance to Target. 13:45.180 --> 13:52.770 So Blackboard Key is distance to Target, and I'm going to check if it's less than or equal to some 13:52.770 --> 13:55.050 pretty big value, like 4000. 13:55.470 --> 14:00.330 So if we're far enough away to approach, we'll approach. 14:00.330 --> 14:07.110 But if we're too close, I want to fail out of this so we can try one of the others and try to attack 14:07.140 --> 14:07.740 again. 14:07.740 --> 14:16.170 In other words, I want to abort if the distance is too close, so I'm going to add another decorator. 14:17.490 --> 14:18.540 Blackboard. 14:18.540 --> 14:21.960 And for this I'm going to check the distance to target again. 14:21.960 --> 14:24.960 But this one will be is greater than or equal to. 14:24.960 --> 14:29.240 And this will be basically our sort of attack distance. 14:29.250 --> 14:35.250 It'll be about, let's say, 500 and we'll abort unless we're greater than or equal to. 14:35.280 --> 14:42.090 So we can actually change the node names on these to make it a little bit easier to understand. 14:42.360 --> 14:47.880 For this distance to target is greater than or equal to 500. 14:47.910 --> 14:52.200 This is are we far away enough to attack? 14:52.200 --> 14:56.040 Because if we're far enough away to attack, we should attack. 14:56.040 --> 15:03.330 So I'm going to rename this one to is far enough to attack. 15:03.600 --> 15:10.110 And this one is are we close enough to approach is the distance less than 4000? 15:10.110 --> 15:11.550 So this will say. 15:12.800 --> 15:15.860 Is close enough to approach. 15:16.220 --> 15:21.440 We can have question marks here as well, and we can even make it a little bit easier to understand. 15:21.440 --> 15:24.620 We can say, Am I close enough to approach? 15:24.620 --> 15:30.480 And here I can say, Am I far enough to attack? 15:30.500 --> 15:32.840 So we will move to the target. 15:32.840 --> 15:37.790 If we're closer than 4000 or equal, we will move to the target. 15:37.790 --> 15:42.590 If we're not too close, are we far away enough? 15:42.620 --> 15:47.920 It should actually say, am I close enough to attack or far enough to approach? 15:47.930 --> 15:55.340 Let's just say, am I far enough to approach trying not to make this too confusing With all the double 15:55.340 --> 15:57.070 negatives and the conditionals. 15:57.080 --> 16:03.640 If distance is greater than 500, we will approach, but otherwise we will not. 16:03.650 --> 16:06.740 If we're too far or too close, we will not approach. 16:06.860 --> 16:10.810 Instead, we'll evaluate one of these other conditions again. 16:10.820 --> 16:12.780 Now we can rename these as well. 16:12.780 --> 16:16.440 This one is checking if the distance is less than 500. 16:16.440 --> 16:17.940 So this one is checking. 16:17.940 --> 16:19.260 Are we close enough to attack? 16:19.260 --> 16:24.390 So we'll say, am I close enough to attack? 16:24.600 --> 16:28.020 And then this one we're checking am I arranged attacker? 16:28.020 --> 16:31.890 So we'll say, am I a ranged attacker? 16:32.580 --> 16:36.690 And arranged attacker should also check a distance as well. 16:36.720 --> 16:41.910 Arranged attacker should attack when it's a little bit farther away so we can have a distance check 16:41.910 --> 16:42.360 here. 16:42.360 --> 16:44.370 Let's add one more decorator. 16:44.370 --> 16:46.050 I'm going to call this one. 16:46.230 --> 16:51.570 Am I close enough to attack? 16:53.580 --> 16:56.760 And this one will also check distance to Target. 16:56.760 --> 17:01.800 But this one will be if we're less than so is less than. 17:01.800 --> 17:04.830 And we'll do a bigger value like 600. 17:05.100 --> 17:12.330 So if we're close enough by 600 units, then for a ranged attacker, we should start attacking with 17:12.330 --> 17:13.770 those ranged attacks. 17:13.770 --> 17:18.840 If we're not arranged attacker and we're not close enough to attack, we'll move on. 17:18.960 --> 17:22.320 But if we're close enough for the melee, we'll attack with melee. 17:22.350 --> 17:25.980 Otherwise we'll then see if we should approach and we'll approach. 17:25.980 --> 17:29.400 Okay, so we have a bit of a skeleton going. 17:29.400 --> 17:36.510 We do need to flesh out these other two cases and give our enemy the ability to attack. 17:36.510 --> 17:37.710 We'll get to that. 17:37.740 --> 17:40.770 I think this is a good stopping point. 17:40.770 --> 17:44.490 And in the videos to come, we'll flesh this out even more. 17:44.490 --> 17:52.050 Before we wrap up, I think we can go ahead and press play and we can see that these things are approaching. 17:58.910 --> 18:00.860 And they kind of just stand there. 18:00.860 --> 18:06.980 Once they've approached, we can see that we're basically in this move to Target. 18:07.700 --> 18:09.020 Part of our tree. 18:12.790 --> 18:15.480 We see that these nodes do nothing. 18:15.490 --> 18:19.420 So we'll get to our move to portion. 18:27.290 --> 18:30.550 And our very basic behavior is working. 18:30.560 --> 18:35.990 We just need to flesh out those other two branches there and we'll do those next. 18:36.080 --> 18:37.110 Great job. 18:37.130 --> 18:38.270 I'll see you soon.