WEBVTT 00:06.900 --> 00:08.130 Welcome back. 00:08.400 --> 00:11.550 Now we have our gameplay ability firebolt. 00:11.640 --> 00:14.940 And so far it's pretty simple. 00:15.030 --> 00:23.010 If we're hovering over an enemy and we left click, we spawn a Firebolt, which is great, but obviously 00:23.010 --> 00:25.140 we have some things that we need to do. 00:25.440 --> 00:32.040 Now in this section we're concerned with talking about ability, tasks and ability. 00:32.040 --> 00:41.640 Tasks are sort of like the workers that a gameplay ability employs to do tasks and things that can be 00:41.640 --> 00:47.280 done either instantaneously or they may span across some period of time. 00:47.280 --> 00:52.860 And there are a number of tasks that already exist in the gameplay ability system. 00:52.860 --> 00:56.010 And of course we have the ability to create our own. 00:56.040 --> 01:01.730 Now the easiest way to learn how tasks work is to just use one of the pre-made tasks. 01:01.740 --> 01:05.580 So if we right click, let's type play montage. 01:05.760 --> 01:15.850 Now if we select play montage under animation montage, this is what we refer to as a latent node. 01:15.880 --> 01:21.970 Latent means a synchronous or a node that will be executed. 01:22.060 --> 01:30.340 And then depending on what happens later, we have a number of output execution pins that can be executed. 01:30.370 --> 01:37.690 Notice that it has an input execution pin and it also has a regular output execution pin. 01:37.930 --> 01:45.820 The regular output execution pin at the very top right is executed immediately after we reach the node. 01:45.910 --> 01:52.960 But then that allows us to continue calling other functions and things right after we've reached the 01:52.960 --> 01:53.680 node. 01:53.710 --> 02:01.450 But then we have a number of circumstances that can trigger these other output execution wires to flow 02:01.450 --> 02:03.190 such as completed. 02:03.190 --> 02:07.630 That's when the montage has finished playing on blend out. 02:07.630 --> 02:15.100 This is executed when the montage begins, blending out and is not interrupted and depending on blend 02:15.130 --> 02:22.720 settings, this might be earlier than completed and usually is on interrupted is self-explanatory. 02:22.750 --> 02:24.640 On notify Begin. 02:24.670 --> 02:33.550 This is executed when using a play montage, notify or a play montage notify window in the montage as 02:33.550 --> 02:40.420 we can put notifies in the montage and then of course notify end is for when a montage notify window 02:40.420 --> 02:41.440 has ended. 02:41.440 --> 02:48.550 As you can see, there are a number of things that can cause any of these situations to trigger. 02:48.550 --> 02:55.200 Now this is just a blueprint latent node, also known as an async task. 02:55.210 --> 03:02.830 Now gas has more specialized forms of these latent nodes and these are more ingrained in the ability 03:02.830 --> 03:04.030 system itself. 03:04.210 --> 03:13.590 For example, if we type play montage, notice that there's another blueprint function under ability 03:13.620 --> 03:14.370 tasks. 03:14.370 --> 03:19.980 This is an ability task and if we click on this one, it looks a lot like the other one. 03:19.980 --> 03:22.290 It just has more options, right? 03:22.290 --> 03:28.500 And if you had browsed through the gameplay ability header file, you may have noticed that there were 03:28.500 --> 03:31.650 some things in there related to montages. 03:31.680 --> 03:35.970 A given ability knows which montage is currently playing. 03:35.970 --> 03:44.130 If we're using the gameplay ability system version of play montage and wait now play montage in wait 03:44.160 --> 03:45.990 is going to do what it says. 03:45.990 --> 03:52.890 It's going to play a montage and then it's going to wait for one of these things to happen for the montage 03:52.890 --> 03:57.090 to complete or blend out or be interrupted or cancelled. 03:57.120 --> 04:03.180 And then of course, we have the topmost execution pin that we can execute things immediately after 04:03.180 --> 04:05.070 reaching the node with. 04:05.100 --> 04:06.930 Now let's see how this works. 04:06.930 --> 04:14.650 I'm going to delete that play montage latent node and leave my play montage in wait ability task node. 04:14.650 --> 04:17.800 And what this can do is it can play a montage. 04:17.800 --> 04:23.670 We can hardcode one in by selecting one here, but that means we need a montage to play, don't we? 04:23.680 --> 04:26.410 So why don't we create a montage real quick? 04:26.410 --> 04:34.540 We can go to content assets, characters, aura animations, abilities and we have this cast Firebolt 04:34.540 --> 04:35.620 animation. 04:35.800 --> 04:37.000 I'd like to use this. 04:37.000 --> 04:44.320 I'm going to right click on it, go to create and create anim montage and I'm going to call this a m 04:44.320 --> 04:48.580 underscore cast underscore Firebolt. 04:48.790 --> 04:50.410 I'm going to double click on it. 04:50.410 --> 04:52.360 And now I have a montage. 04:53.760 --> 04:56.790 Now it's set to the default slot. 04:56.820 --> 05:02.040 All montages are set to use the default slot by default. 05:02.050 --> 05:02.580 Right. 05:02.640 --> 05:09.780 But we do need to be using that default slot and it's a good idea to just double check in our animation 05:09.780 --> 05:10.290 blueprint. 05:10.290 --> 05:16.560 So in Blueprints Character Aura, here's our animation blueprint app Aura. 05:16.740 --> 05:22.440 And yes, we created the default slot node here and we're running our pose through it. 05:22.440 --> 05:27.480 So if we play this montage, we'll actually successfully see it played. 05:27.630 --> 05:31.770 So we have a montage called Arm Cast Firebolt. 05:31.770 --> 05:38.460 So if we go back to our gameplay ability and open our dropdown, we now see the montage, we can select 05:38.460 --> 05:45.660 that and play montage and weight is going to play the montage and we can just see that this topmost 05:45.660 --> 05:54.510 execution wire is executed right away by printing a string that says Casting Firebolt. 05:54.510 --> 06:03.000 And if we compile and press play and click on an enemy, we see that we're playing that montage and 06:03.030 --> 06:08.640 of course we're spawning the projectile immediately, which doesn't look right, but we're playing the 06:08.640 --> 06:09.300 montage. 06:09.330 --> 06:15.180 Now let's open that montage back up and make sure that we're okay with our blend options. 06:15.210 --> 06:20.220 Our blend in under blend option is set to 0.25. 06:20.220 --> 06:26.520 I'd like this to be zero so we have no blending and for blend out, I'm okay with a little blending, 06:26.520 --> 06:27.840 but less than that. 06:27.840 --> 06:31.530 I want 0.1 and then we can test this out. 06:32.460 --> 06:33.300 That looks better. 06:33.300 --> 06:40.740 I want to just start playing the montage with no blending at all so it's a lot faster, more responsive. 06:40.770 --> 06:43.230 You can have some blending here if you want. 06:43.440 --> 06:48.860 If you prefer to have it less snappy, you can have a blend in time. 06:48.870 --> 06:53.160 I like them very low, so like 0.05 is a good blend time. 06:53.160 --> 07:00.360 So as we can see, we play the montage and immediately we get that print string node because that print 07:00.360 --> 07:06.060 string node is reached immediately after play montage and wait. 07:06.240 --> 07:08.790 However we can do things later. 07:08.790 --> 07:11.670 That's what async tasks are good for. 07:11.670 --> 07:19.560 We can do something when Oncompleted is executed so we can just drag off of this, use a print string 07:19.560 --> 07:22.200 and say Oncompleted. 07:22.800 --> 07:25.650 We can also do something on blend out. 07:25.650 --> 07:30.570 So we'll do a print string in this case that says on Blend out 07:33.300 --> 07:40.560 and then we'll do a print string for the other two here we're going to say on Interrupted. 07:42.360 --> 07:44.280 And then on cancelled. 07:46.300 --> 07:48.010 We'll say on Canceled. 07:49.790 --> 07:52.490 So that way we can see which of these gets called. 07:52.580 --> 07:55.310 So we'll go ahead and activate our ability. 07:56.090 --> 08:01.730 And then we see that on blend out and on completed happened, right? 08:01.760 --> 08:03.230 They get executed. 08:03.350 --> 08:03.980 Why? 08:04.010 --> 08:13.100 Because we start blending out first and that's why we get that message first and then on completed happens 08:13.100 --> 08:21.290 because shortly after we began blending out, the montage completes and we're not interrupting or canceling 08:21.290 --> 08:21.920 the montage. 08:21.920 --> 08:24.500 So those print strings don't get called. 08:24.500 --> 08:31.250 But we saw that a short period of time elapsed before on Blend out and on completed were executed. 08:31.400 --> 08:39.110 This allows us to do things later in time without needing to go through the trouble of using timers 08:39.110 --> 08:40.070 and things like that. 08:40.070 --> 08:44.510 We can base things on the length of a montage, so this is great. 08:44.540 --> 08:50.160 Now we know how to use the blueprint node, but how does this work under the hood? 08:50.160 --> 08:58.440 How does a blueprint node become async and how does it wait until something happens and then execute 08:58.440 --> 09:02.190 these wires conditionally based on what's going on in the game? 09:02.310 --> 09:08.910 Well, I'm going to close and save all and I'm going to hit double shift so I can search my solution 09:08.910 --> 09:11.940 and I'm going to search for play montage and wait. 09:12.420 --> 09:19.320 And we see this U ability task play montage and wait and it's in the header file with that name. 09:19.320 --> 09:25.320 I'm going to click on that and we see that this is a class based on U ability task. 09:25.680 --> 09:29.430 The comment says ability task to simply play a montage. 09:29.460 --> 09:35.190 Many games will want to make a modified version of this task that looks for game specific events. 09:35.220 --> 09:37.350 Now let's take a look at this class. 09:37.350 --> 09:40.920 Here in the class, we have a number of delegates. 09:41.280 --> 09:49.080 We have an F montage weight, simple delegate, and there are four of them on completed on blend out 09:49.110 --> 09:51.660 on interrupted and on canceled. 09:51.690 --> 09:55.590 Those were the names of those output execution pins. 09:55.590 --> 10:03.150 So when you create an ability task and you add some blueprint assignable delegates to it, then those 10:03.150 --> 10:07.650 become output execution pins for the ability task node. 10:08.040 --> 10:10.770 So we have some comment here. 10:10.770 --> 10:15.720 And this big comment is right above this right here. 10:15.840 --> 10:25.830 And what we have is a static function called create play montage and wait proxy that returns a pointer 10:25.830 --> 10:29.730 of type U ability task play montage and wait. 10:29.760 --> 10:36.780 Now this is a blueprint callable, it has a category, it has a meta with display name, play, montage 10:36.780 --> 10:42.870 and wait, which means that the blueprint node for this function is going to say play montage and wait. 10:42.870 --> 10:46.650 It doesn't have the u ability task in front of it. 10:46.680 --> 10:54.900 It also has hide pin owning ability so this means that the blueprint node is not going to show this 10:54.930 --> 10:58.380 input parameter for this function called owning ability. 10:58.590 --> 11:06.240 It also has default to self owning ability, which means that not only are we hiding this input parameter 11:06.240 --> 11:13.830 as a pin from the blueprint node, we're saying to default this owning ability to self in C plus plus 11:13.830 --> 11:15.030 that would be this. 11:15.030 --> 11:21.570 And we see blueprint internal use only set to true, which if we hover over it says this function is 11:21.570 --> 11:27.030 an internal implementation detail used to implement another function or node. 11:27.030 --> 11:30.150 It is never directly exposed in a graph. 11:30.390 --> 11:38.010 When we create this static function that returns the type of the class that we're in like this with 11:38.010 --> 11:45.990 these specific U function specifiers, this creates our latent node that we saw in Blueprint. 11:46.020 --> 11:53.850 Now, if we go to the CPP file and take a look at the definition of that static function, we can scroll 11:53.850 --> 11:54.780 down and find it. 11:54.780 --> 11:55.680 Here it is. 11:55.680 --> 11:57.420 We can see what it's doing. 11:57.420 --> 12:04.920 Ultimately, it's creating a new ability task with this function, new ability, task, specifying this 12:04.920 --> 12:11.550 particular task, and then it's setting a number of parameters on that new task and returning it. 12:11.550 --> 12:18.330 So these ability tasks have this static function that creates an instance of themselves and returns 12:18.330 --> 12:25.440 it after setting a number of input parameters that can be exposed to the blueprint. 12:25.440 --> 12:32.340 So this is made to be created in blueprint, although the function itself could be called in C plus 12:32.340 --> 12:33.390 plus of course. 12:33.390 --> 12:39.150 And then we know that this particular class has a number of delegates right now. 12:39.150 --> 12:46.080 As soon as we've created this ability, task ability tasks have an activate function and when they're 12:46.080 --> 12:48.480 activated, whatever we have in this activate. 12:48.510 --> 12:51.340 Function is what happens now. 12:51.360 --> 12:56.620 Play montage and wait, as we would probably imagine, is going to play a montage. 12:56.640 --> 12:58.550 We can see that right here. 12:58.560 --> 13:03.480 It's calling play montage on guess what an ability system component. 13:03.510 --> 13:07.680 How does it know which ability system component to play the montage on? 13:07.830 --> 13:12.060 Well, ability tasks have an owning ability system component. 13:12.090 --> 13:15.450 They have a variable called ability system component. 13:15.450 --> 13:20.430 And this particular ability task is just calling play montage on it. 13:20.460 --> 13:25.080 Notice that it's also binding some function callbacks to some delegates. 13:25.200 --> 13:28.250 These are those delegates we looked at in the header file. 13:28.260 --> 13:32.610 It's binding its own on montage blending out function. 13:32.610 --> 13:35.880 And what does on montage blending out do? 13:35.910 --> 13:37.110 Well, here it is. 13:37.110 --> 13:38.610 We see what it's doing. 13:38.710 --> 13:43.200 It calls clear animating ability on the ability system component. 13:43.320 --> 13:44.850 It gets the character. 13:44.850 --> 13:45.750 How does it get it? 13:45.750 --> 13:47.880 It gets it from the avatar actor. 13:47.880 --> 13:49.770 So it has a function. 13:49.770 --> 13:51.260 Get Avatar actor. 13:51.270 --> 13:56.990 It's checking for authority and then calling set and root motion translation scale. 13:57.000 --> 14:00.030 We don't have to get too deep in what all these do. 14:00.060 --> 14:02.250 This function is self-explanatory. 14:02.250 --> 14:07.650 If you're using root motion, that root motion can be scaled for its translation. 14:08.070 --> 14:10.890 This function checks to see if it's being interrupted. 14:10.890 --> 14:13.490 If so, it broadcasts on interrupted. 14:13.500 --> 14:15.750 Same thing for on blend out. 14:15.990 --> 14:22.250 So as you can see, the class has a number of callbacks bound to the delegates that it has. 14:22.260 --> 14:30.360 So the takeaway here is that an ability task is basically this C plus plus class that has a static function, 14:30.390 --> 14:36.900 a sort of factory of sorts that constructs an instance of itself that's blueprint callable exposed to 14:36.900 --> 14:37.740 blueprint. 14:37.740 --> 14:44.490 And the class has a number of delegates that are broadcast based on things that are happening. 14:44.490 --> 14:52.500 And it has an activate function usually in which those delegates have some callbacks bound to them. 14:52.500 --> 14:58.470 And these delegates can be broadcast based on whatever logic we implement here. 14:58.500 --> 15:00.270 Play montage and wait. 15:00.270 --> 15:07.890 Just happens to play a montage and broadcast delegates when the montage is finished or in any number 15:07.890 --> 15:16.560 of related cases to that, you'll see that our ability task is getting the anim instance from the actor 15:16.560 --> 15:23.400 info associated with this ability tasks, ability and owning ability system component and getting a 15:23.400 --> 15:30.450 montage set blending out delegate and then that results in this delegate having its callback executed 15:30.450 --> 15:32.850 which is on montage blending out. 15:32.850 --> 15:37.980 So as you can see, there are lots of delegates and this will make a lot more sense when we create an 15:37.980 --> 15:39.840 ability task of our own. 15:40.050 --> 15:46.740 But this deep dive is just to show what's going on behind the scenes with this play montage and wait. 15:46.860 --> 15:53.040 So now that we've seen what play montage and wait is sort of doing behind the scenes, we can use play 15:53.040 --> 15:59.610 montage and wait in our gameplay ability and that's going to make things easier for us when we need 15:59.610 --> 16:04.110 to play a montage in a given gameplay ability and wait for something to happen. 16:04.230 --> 16:09.510 Now, what if we want to wait for something that's not one of these cases? 16:09.720 --> 16:16.710 What if we want to wait until a certain point in our montage before we do the next thing, such as spawn 16:16.710 --> 16:17.910 our projectile? 16:17.910 --> 16:22.890 For example, here in our montage, we don't want to spawn our projectile here. 16:22.890 --> 16:30.570 We want to wait until a certain point in the animation, maybe right here to spawn that projectile. 16:30.600 --> 16:33.870 In other words, we might want to create some kind of anim notify. 16:34.200 --> 16:40.770 So how do we know once we've reached a certain point inside of our anim montage so that we can do the 16:40.770 --> 16:45.630 next step in our gameplay ability, such as spawning the projectile? 16:45.720 --> 16:49.830 That's going to be the topic of our next discussion. 16:49.830 --> 16:51.900 So we'll take care of that next. 16:52.350 --> 16:53.180 Great job. 16:53.190 --> 16:54.240 I'll see you soon.