WEBVTT 00:06.830 --> 00:07.880 Welcome back. 00:07.910 --> 00:10.790 Now here's my gameplay effect G damage. 00:10.820 --> 00:13.940 It's set to modify incoming damage. 00:13.940 --> 00:15.470 That's our meta attribute. 00:15.500 --> 00:20.270 We're adding to it and the magnitude calculation type is set by caller. 00:20.270 --> 00:27.470 So we've seen that we can set a set by caller magnitude from game logic either in C plus plus or it 00:27.470 --> 00:32.330 can be done in blueprint and that's the magnitude calculation type. 00:32.510 --> 00:37.340 But we can also set this to a custom calculation class if we like. 00:37.340 --> 00:44.030 And execution calculations are another choice for our custom calculation class. 00:44.030 --> 00:50.900 In addition to MKs, we're going to make one for damage because our damage calculation is going to be 00:50.900 --> 00:55.670 quite a bit more complex than simply setting a value directly. 00:55.670 --> 00:57.560 So let's make that class. 00:57.560 --> 01:03.770 We're going to go into C plus plus classes, Aura, public ability system. 01:03.860 --> 01:10.440 And here's a mod mag calc folder where we could have called this custom calculations and just keep all 01:10.440 --> 01:16.470 our custom calcs in there, but we're going to make a new C plus plus class in a new folder. 01:16.590 --> 01:23.340 So for this it's going to be a gameplay effect execution calculation. 01:23.730 --> 01:30.240 So we'll choose that type and we'll place it in ability system slash exec calc. 01:30.270 --> 01:36.270 So that's a shorthand way of referring to an execution calculation. 01:36.270 --> 01:38.280 We often call them exec Calcs. 01:38.550 --> 01:45.810 Now I'm going to prefix this with exec calc underscore, and I'm going to call this damage. 01:45.810 --> 01:48.480 So we'll have a exec calc damage. 01:48.480 --> 01:50.490 Let's go ahead and create the class. 01:50.490 --> 01:52.800 And I'm going to close the editor down. 01:52.800 --> 02:00.030 And this should show up right in my ability system and exec calc folder so I can go ahead and close 02:00.030 --> 02:05.460 all the tabs and open the exec calc and CPP files. 02:05.550 --> 02:13.410 So here's our custom calculation class based on you gameplay effect execution calculation. 02:13.410 --> 02:15.840 It's called you exec calc damage. 02:15.840 --> 02:20.760 And we've seen in the last slide just what this type of class is capable of. 02:20.790 --> 02:23.850 We just don't know yet how to implement that. 02:23.850 --> 02:27.300 So here are the things we have to do just by default. 02:27.300 --> 02:34.320 The first things to do are, first, we need a constructor, so we're going to add a public section. 02:35.910 --> 02:41.010 And we'll add a constructor and we'll define the constructor. 02:41.100 --> 02:42.510 So that's step one. 02:42.510 --> 02:51.120 And then we need to decide what happens when this custom calculation class is executed, what type of 02:51.120 --> 02:57.030 calculations are going to occur, And for that we override a virtual function. 02:57.030 --> 03:03.420 It's a virtual void function and it's called execute underscore implementation. 03:03.780 --> 03:11.400 Now, if I let writer complete this, for me it's a function with a couple of input parameters. 03:11.400 --> 03:20.100 First is an input called execution params, it's an gameplay effect custom execution parameters. 03:20.250 --> 03:24.140 So it's a little struct that contains some information. 03:24.150 --> 03:28.890 We also have an gameplay effect custom execution output. 03:28.890 --> 03:36.690 It's called out execution output and that's not const, that's just by reference indicating that perhaps 03:36.690 --> 03:44.850 we can change this struct in some way and it will be used somewhere later after this function has been 03:44.850 --> 03:45.690 executed. 03:45.690 --> 03:50.100 So we have this function, we can generate a definition for it. 03:51.040 --> 03:52.390 So here we have it. 03:52.390 --> 03:53.950 And we don't have to call super. 03:53.950 --> 03:57.920 We can just decide exactly what happens here. 03:57.940 --> 04:06.340 And what we're deciding is how this execution calculation is going to affect any other attributes by 04:06.340 --> 04:07.790 setting their values. 04:07.810 --> 04:11.050 So remember, this belongs in a gameplay effect. 04:11.050 --> 04:18.040 So if we add a modifier to the gameplay effect, then by setting a custom calculation class, it's really 04:18.040 --> 04:25.120 this custom calculation class that determines what's going to happen when we apply that gameplay effect. 04:25.240 --> 04:33.460 So here we can decide how to change various attributes and we can capture attributes and we can also 04:33.460 --> 04:39.880 get information about the gameplay effect concerning who caused the effect and who the effect is targeting 04:39.880 --> 04:41.930 at the time of application. 04:41.950 --> 04:49.600 So we're just going to start off by retrieving some data that's available to us thanks to these input 04:49.600 --> 04:51.980 parameters that we have at our disposal. 04:52.100 --> 04:57.680 We're going to take a look at the execution params, so let's type execution params. 04:59.100 --> 05:01.020 And have a dot here. 05:01.020 --> 05:06.420 And notice that as soon as we hit dot, we have lots and lots of cool functions. 05:06.540 --> 05:12.810 Some of the most notable are look at this git owning spec, the gameplay effect spec that owns this 05:12.810 --> 05:13.860 calculation. 05:14.070 --> 05:16.170 There's the prediction key. 05:17.160 --> 05:22.950 We have some functions that sound like they're related to capturing attributes and their magnitudes. 05:23.190 --> 05:27.300 And we also have things like get source ability system component. 05:29.250 --> 05:31.680 And get target ability system component. 05:31.680 --> 05:35.280 These are really nice and convenient functions for us. 05:35.280 --> 05:38.180 Let's say we'd like the source ability system component. 05:38.190 --> 05:39.210 Well here it is. 05:39.210 --> 05:46.860 We can call that function and we can even store it in a const you ability system component pointer called 05:46.860 --> 05:49.830 source ASC for example. 05:50.190 --> 05:52.440 We can also do that with the target. 05:52.440 --> 06:02.130 So we can say const you ability system component target ASC equals execution params dot get target ability 06:02.130 --> 06:03.360 system component. 06:03.360 --> 06:08.400 So right there we've already got the ability system components of the source and the target. 06:08.610 --> 06:13.140 Now because we have these, we can also get the Avatar actors. 06:13.140 --> 06:21.900 If we need those, for example, we can make an A actor pointer called Source Avatar for example, and 06:21.900 --> 06:24.570 we can get that from the source ability system component. 06:24.600 --> 06:30.610 Now in the case that the source ability system component is null, then we'll just set this source actor 06:30.610 --> 06:31.120 to null. 06:31.150 --> 06:32.020 How about that? 06:32.020 --> 06:37.660 So we can use the ternary operator and say source ASC question mark. 06:37.660 --> 06:45.670 And if that is not null, then we'll take source ASC and call get Avatar actor and if it is null, we'll 06:45.670 --> 06:52.810 set this source avatar to a null pointer and we can do that for the source and the target for now we 06:52.810 --> 06:54.130 can make them const. 06:54.750 --> 06:56.760 So const a actor. 06:58.600 --> 07:05.530 And we'll make a target avatar and we'll check Target ask question mark. 07:06.400 --> 07:08.770 If it's valid, we'll take target. 07:08.800 --> 07:12.190 Ask and call get Avatar actor. 07:12.220 --> 07:14.770 Otherwise we'll set it to null pointer. 07:15.640 --> 07:22.030 So right there we have the ability system components and the avatar actors for the source and the target 07:22.060 --> 07:25.450 of the gameplay effect using this custom calculation. 07:25.570 --> 07:32.350 We can also get the effect spec as we've seen, so we can make a const gameplay effect spec. 07:32.470 --> 07:39.250 I'm going to make it a const reference called spec and we can get that from the execution params with 07:39.250 --> 07:40.690 get owning spec. 07:40.780 --> 07:44.710 So that right there has tons of information inside of it. 07:44.920 --> 07:45.700 All right. 07:45.700 --> 07:52.960 So now that we know that we can access source and target ability system component and avatar actors 07:52.960 --> 07:58.540 as well as lots of other information in the effects spec, we need to know how we can capture attributes 07:58.690 --> 08:04.890 and use them and set them and really make this execution calculation do its thing. 08:04.900 --> 08:09.220 Now, at some point it looks like writer Auto included something up there that's not used for me. 08:09.220 --> 08:10.780 I'm going to go ahead and remove it. 08:10.990 --> 08:12.070 There we go. 08:12.460 --> 08:20.320 So next, we need to actually capture some attributes and then decide how we're going to use those to 08:20.320 --> 08:22.180 change other attributes. 08:22.180 --> 08:28.870 Ultimately, this damage exec calc is going to want to set the damage meta attribute on the target. 08:28.870 --> 08:31.270 So that's one of the next things we need to do. 08:31.270 --> 08:37.780 So in the next video, we're going to learn how we can start capturing attributes in our execution calculation. 08:38.200 --> 08:39.340 I'll see you soon.