WEBVTT 00:06.900 --> 00:07.980 Welcome back. 00:08.010 --> 00:12.990 Our widget controller is now capable of broadcasting initial values. 00:13.080 --> 00:20.100 We know that we can cast our attribute set to an aura, attribute set and access those attribute values 00:20.100 --> 00:22.080 with those attribute accessors. 00:22.080 --> 00:29.400 That's great, but we're going to want to be able to respond to when those attributes change and the 00:29.400 --> 00:34.230 ability system component has a function for doing just that. 00:34.290 --> 00:35.580 It looks like this. 00:35.730 --> 00:44.070 We take the ability system component pointer and we call get gameplay attribute value change delegate. 00:44.070 --> 00:48.660 This function needs to know what attribute we're talking about. 00:48.690 --> 00:52.230 Well, we could always get that from aura attribute set. 00:52.230 --> 00:58.770 If we're talking about the health attribute, we'd take aura, attribute set and call get health attribute 00:58.770 --> 01:01.740 that returns an if gameplay attribute. 01:01.740 --> 01:03.990 That's what this function requires. 01:03.990 --> 01:09.760 So this returns the delegate and if we want we can bind to that delegate. 01:09.760 --> 01:18.910 It returns an on gameplay attribute value change delegate and to bind to it we use the dot operator 01:18.910 --> 01:22.960 and we use the function add you object. 01:22.990 --> 01:30.640 Now, if this were a dynamic multicast delegate, we could use add dynamic, but gameplay attribute 01:30.640 --> 01:39.040 value change if we right click and go to declaration or usages and then right click on this gameplay 01:39.040 --> 01:44.380 attribute value change and go to its declaration or usages. 01:44.380 --> 01:50.140 We see that it's a multicast delegate, it's not a dynamic multicast, so we can't use Add dynamic. 01:50.140 --> 01:57.460 We have to use Add you object and to bind a callback to it, we pass in this followed by the callback 01:57.460 --> 02:05.620 function and the callback function has to have a specific signature to be able to be bound to this delegate. 02:05.620 --> 02:09.220 So we really need to create a function to bind to it. 02:09.220 --> 02:12.970 And so that's one of the next things that we need to do. 02:13.150 --> 02:21.520 But really before we do that, binding callbacks to the dependencies of this widget controller is something 02:21.520 --> 02:23.770 that all widget controllers need to do. 02:23.980 --> 02:29.560 So we're going to make a function that we can use to bind our callbacks to all those dependencies. 02:29.740 --> 02:33.370 Let's add that to our Aura widget controller. 02:33.400 --> 02:38.950 That's the parent class, and that way all widget controllers can implement that function. 02:38.950 --> 02:45.580 So I'm going to make it a virtual void function and I'm going to call it bind callbacks to dependencies. 02:47.500 --> 02:51.670 So this will be a very important step that our widget controllers have to go through. 02:51.850 --> 02:57.190 I'm going to generate the definition, but leave it blank because I want my overlay widget controller 02:57.190 --> 02:58.750 to override it. 02:58.780 --> 03:03.340 So here an overlay widget controller just under broadcast initial values. 03:03.340 --> 03:11.140 I'm going to override virtualvoid, bind callbacks to dependencies and go ahead and generate the definition 03:11.140 --> 03:11.830 here. 03:11.830 --> 03:15.790 And I don't care about calling super in this case. 03:15.790 --> 03:22.660 I'm just going to bind callbacks here and we need a callback that we can bind to that delegate that's 03:22.660 --> 03:27.640 broadcast whenever our attributes change, such as health and max health. 03:27.640 --> 03:31.630 So I'd like a callback function for each of these. 03:31.630 --> 03:36.820 So let's go to our H file and I'm going to make these protected. 03:37.660 --> 03:39.820 They're going to be void functions. 03:39.820 --> 03:42.850 And for health, I'm just going to call it health changed. 03:43.390 --> 03:49.760 Now here's the signature that it has to have to bind to those delegates on the ability system component. 03:49.790 --> 03:56.870 It has to be a const reference to F on attribute change data. 03:56.990 --> 03:59.900 So we have a const reference, we're going to call it data. 03:59.990 --> 04:04.070 So I'll have one for health changed and I'll have one for max health change. 04:04.070 --> 04:11.420 So I'll go ahead copy and paste that and change it to max health changed and we can create definitions 04:11.420 --> 04:12.800 for these. 04:16.560 --> 04:25.320 Now these functions have a signature that qualifies them to bind to the delegate that is broadcast when 04:25.320 --> 04:26.790 an attribute changes. 04:26.820 --> 04:29.960 And so we'll do that here in bind callbacks to dependencies. 04:29.970 --> 04:36.540 So I'm going to take my line here where we're getting our attribute set and casting to our attribute 04:36.540 --> 04:38.280 set as I need that. 04:38.280 --> 04:45.960 And after that I'm going to take the ability system component and call get gameplay attribute value 04:45.960 --> 04:51.330 change delegate passing in the attribute that I want to bind a callback for. 04:51.360 --> 04:53.190 So first I'll do it for health. 04:53.190 --> 04:58.290 So I'll get aura attribute set and call get health attribute. 04:58.590 --> 05:02.130 So this whole expression here returns that delegate. 05:02.130 --> 05:10.080 So I'm going to use the dot operator here and call add you object passing in this for the user object 05:10.080 --> 05:18.550 and the address of my health changed function callback fully qualified with the class name here like 05:18.550 --> 05:19.270 so. 05:19.270 --> 05:24.900 And now whenever the health changes, this function callback will be called. 05:24.910 --> 05:25.900 Now that's a lot. 05:25.930 --> 05:27.250 All on one line. 05:27.250 --> 05:29.050 If you want, you can break it up. 05:29.080 --> 05:33.850 You can say put an enter there and there. 05:33.850 --> 05:35.830 If you want to do that, you can put it. 05:35.830 --> 05:37.690 Enter there and there. 05:37.690 --> 05:38.650 Put a new line. 05:38.650 --> 05:39.790 It's up to you. 05:39.790 --> 05:45.790 I'm going to go ahead and organize it like this on two lines. 05:45.790 --> 05:48.050 I think that's enough for me. 05:48.070 --> 05:50.320 And there we have it. 05:50.320 --> 05:56.680 So I've bound health changed to this delegate for when our health attribute changes. 05:56.680 --> 06:04.420 So really it's this part here the input for get gameplay attribute value change delegate. 06:04.450 --> 06:11.890 This is the attribute we specify and then this is the callback that we specify specifically. 06:11.890 --> 06:17.560 So if I want to do this for max health change, I can copy these lines, paste them here and instead 06:17.560 --> 06:24.460 of get health attribute, I can call get max health attribute and instead of health change I can use 06:24.460 --> 06:27.160 my callback that I called max health changed. 06:27.940 --> 06:31.920 So now these functions will be called when the attributes change. 06:31.930 --> 06:34.690 So what do we want to do when the health changes? 06:34.720 --> 06:40.930 Well, I just want to broadcast my on health change delegate so my widgets can respond to it. 06:40.930 --> 06:43.000 So I'm going to broadcast it there. 06:43.030 --> 06:47.590 Now, I don't need to access it from aura attribute set. 06:47.620 --> 06:50.700 I actually have that information here in data. 06:50.710 --> 06:59.980 So in order to get the new value from data, I can take this broadcast call and pass in data dot new 06:59.980 --> 07:00.700 value. 07:01.000 --> 07:05.740 And that's how we get that new value that has just changed for the attribute. 07:05.770 --> 07:08.530 Now writer says this can be made const. 07:08.530 --> 07:11.980 So let's listen to writer and why not? 07:12.010 --> 07:13.960 We'll make these functions const. 07:15.630 --> 07:19.170 That means we need to put const here on the definitions as well. 07:20.820 --> 07:23.220 Now for Maxhealth change, we'll do the same thing. 07:23.220 --> 07:24.390 We'll take this line. 07:25.040 --> 07:28.280 Paste it here, except instead of on health changed. 07:28.310 --> 07:34.280 We're going to broadcast the on max health changed broadcasting data new value. 07:34.310 --> 07:40.760 So now whenever health and max health attributes change, these delegates will be broadcast and our 07:40.760 --> 07:45.770 widgets are already bound to on health changed and on max health changed. 07:45.920 --> 07:51.290 At least our health globe widget is bound to these so we can test this out. 07:51.320 --> 07:57.380 We know that our health potion adds to our health and if we go to our attributes set and instead of 07:57.420 --> 08:03.860 emitting our health to 100, we can emit our health to 50, for example, and leave our max health at 08:03.860 --> 08:04.490 100. 08:04.520 --> 08:09.890 That way our health globe will start off half empty or half full, depending on whether you're an optimist 08:09.890 --> 08:10.910 or a pessimist. 08:10.910 --> 08:18.140 And then once we pick up the health potion, we should see that health globe go up to 75% because our 08:18.140 --> 08:21.170 health potion adds 25 to our health. 08:21.820 --> 08:25.780 So tying this all together is going to be your quest. 08:25.810 --> 08:32.950 We never actually called bind callbacks to dependencies, so you're going to need to call that function. 08:32.950 --> 08:36.190 So you need to think about where this should be called. 08:36.220 --> 08:38.980 When is it appropriate to call this function? 08:38.980 --> 08:44.860 Once you've called it, you can play test, go pick up a health potion and see if that health globe 08:44.860 --> 08:48.520 changes in response to the attribute change. 08:48.520 --> 08:52.120 So pause the video and conquer this quest now. 08:55.480 --> 09:01.600 Okay, so the question arises, where do we call bind callbacks to dependencies? 09:01.810 --> 09:07.120 Well, let's take a look at where we're calling broadcast initial values. 09:07.210 --> 09:10.000 That would be over here in the HUD. 09:10.030 --> 09:17.350 When we call init overlay, right, we're broadcasting initial values there, so you might have thought 09:17.350 --> 09:19.030 maybe I can call it there. 09:19.060 --> 09:25.480 Well, we also have get overlay widget controller, which is where that widget controller is constructed 09:25.480 --> 09:27.280 for the very first time. 09:27.310 --> 09:32.260 Now this will be called when we call get overlay widget controller. 09:32.260 --> 09:37.840 So if we place it in that function, those callbacks will be bound to the dependencies there. 09:38.140 --> 09:43.900 So I think that's a great place to put it and that's where I'm going to put that function call. 09:43.900 --> 09:51.280 So as soon as we set the widget controller params, we know that those key variables are set. 09:51.490 --> 09:54.820 As soon as those are set, I'm going to bind callbacks. 09:54.820 --> 10:03.590 So I'm going to take overlay widget controller and call bind callbacks to dependencies right here. 10:04.190 --> 10:06.980 Just before we return the widget controller. 10:07.310 --> 10:13.580 And then we know that the widget controller is callbacks will be bound so that when those attributes 10:13.580 --> 10:21.320 change or whatever other dependencies we bind callbacks to change, we'll get the change broadcast. 10:21.500 --> 10:23.810 So I'm going to run in debug mode. 10:24.590 --> 10:32.660 Let writer compile and we should see a half full health globe since we're now initializing health to 10:32.660 --> 10:35.300 50 and max health to 100. 10:35.330 --> 10:39.150 So I'm hoping to see a half full health globe here. 10:39.170 --> 10:40.160 I'm going to press play. 10:40.190 --> 10:40.810 There it is. 10:40.820 --> 10:42.400 It looks about half full. 10:42.410 --> 10:46.310 And if I pick up this health potion, it goes up. 10:46.310 --> 10:47.450 Look at that. 10:47.690 --> 10:48.770 Excellent. 10:48.770 --> 10:51.150 So that is looking great. 10:51.170 --> 10:56.330 We now have our health globe reacting to changes in our ability system. 10:56.330 --> 11:04.670 We can even double check by entering the console command show debug ability system and we can see that 11:04.670 --> 11:06.280 our health is now 75. 11:06.290 --> 11:15.190 It started at 50, but we picked up a health potion and now we have 75% as shown on the health globe. 11:15.200 --> 11:16.880 So this is looking great. 11:17.150 --> 11:26.220 Now, it seemed like a lot of work to set all this up, but now we have a class designed to handle controlling 11:26.220 --> 11:29.370 the widget data and retrieving it from the system. 11:29.550 --> 11:33.720 And the way we have it set up, our dependencies are all one way. 11:33.750 --> 11:39.840 Our ability system component knows nothing about the overlay widget controller. 11:40.020 --> 11:41.940 It's completely independent of it. 11:41.940 --> 11:47.160 An overlay widget controller knows nothing of the widgets that are bound to its delegates. 11:47.160 --> 11:49.170 They're completely independent of it. 11:49.290 --> 11:54.540 This is going to be a very powerful system as we'll see throughout this course. 11:54.540 --> 11:58.110 So excellent job and I'll see you in the next video.