WEBVTT 00:06.810 --> 00:07.870 Welcome back. 00:07.890 --> 00:13.380 Now, congratulations on that last lecture because we've now done something a little bit more advanced, 00:13.380 --> 00:14.610 and that's pretty cool. 00:14.640 --> 00:19.450 We now have a way for our new custom context to be serialized. 00:19.470 --> 00:23.520 Our custom effect context has its own net serialize. 00:23.880 --> 00:26.820 Now, that's not the only thing that an effect. 00:26.820 --> 00:30.150 Context needs to be serializable. 00:30.180 --> 00:37.530 There's another important step, and we can see that if we go to gameplay effect types and scroll down 00:37.530 --> 00:40.590 to the bottom of our effect context class. 00:40.590 --> 00:47.910 In fact, just past the bottom of it, we'll see this struct here, which is a template defined. 00:48.180 --> 00:56.440 Now this struct is called t struct ops type traits, but it's not just any struct ops type traits. 00:56.460 --> 01:00.780 It's specified with gameplay effect context. 01:00.780 --> 01:08.640 So this is defining a struct called struct ops type traits for this particular template parameter. 01:08.670 --> 01:12.300 Now this is derived from t struct ops type traits. 01:12.300 --> 01:19.800 Base two and notice we have enum here and each enumerator is set to a true or false value. 01:19.830 --> 01:26.430 That may seem a little bit strange if you've never seen that before, but enums are integers and true 01:26.430 --> 01:30.060 and false can be treated like zeros and ones. 01:30.090 --> 01:30.810 Right? 01:31.020 --> 01:34.890 Now what do these mean and why do we have this here? 01:34.920 --> 01:43.980 Well, these t struct ops type traits defines what can be done with this particular struct f gameplay 01:43.980 --> 01:45.420 effect context. 01:45.420 --> 01:53.340 And these qualities here that are set to true are important for things like serialization and for the 01:53.340 --> 01:54.540 reflection system. 01:54.550 --> 02:01.260 If I right click on t struct ops type traits base two and I go to the declaration or usages, it's going 02:01.260 --> 02:08.860 to take me to class dot h and the comment says type traits to cover the custom aspects of a script struct. 02:08.860 --> 02:13.690 So this has to do with the script struct which is used by the reflection system. 02:13.690 --> 02:21.820 It's also used for other important things like serialization and the struct ops type traits just defines 02:21.820 --> 02:24.550 what that script struct is capable of doing. 02:24.670 --> 02:29.890 And there are quite a few options here and to define what can be done with that script. 02:29.890 --> 02:37.510 Struct you set one of these enum constants to true in order for that script struct to have that capability. 02:37.720 --> 02:44.110 Now you can go through these and read them all if you like, but really we just care about two of them. 02:44.110 --> 02:51.250 The two that are set here in gameplay effect types with net serializer and with copy. 02:51.900 --> 02:58.950 So let's take a look at the comments in class for those two we have with net serializer. 02:59.220 --> 03:07.380 And the comment says struct has a net serialize function for serializing its state to an archive used 03:07.380 --> 03:08.820 for network replication. 03:08.820 --> 03:16.320 So because we wish to do this, we need to set this to true with our struct ops type traits for our 03:16.320 --> 03:17.430 custom struct. 03:17.460 --> 03:24.810 Now we also have the width copy set to true and it says struct can be copied via its copy assignment. 03:24.810 --> 03:25.820 Operator. 03:25.830 --> 03:28.440 So there's that if we'd like that. 03:28.440 --> 03:36.150 And by the way we saw that in game play effect types, there was this nice copy function, it was a 03:36.150 --> 03:40.080 duplicate handling, creating a copy of this context. 03:40.080 --> 03:46.170 If we want this, we could just simply copy, for lack of a better word, and we can paste this into 03:46.170 --> 03:50.400 the public section in our struct so we can put that. 03:50.400 --> 03:53.560 I'm going to put it right above net serialize there. 03:53.560 --> 03:58.180 But what we really need though is our struct ops type traits. 03:58.480 --> 04:02.890 So we declare that down here just below the class, it's a template. 04:02.890 --> 04:13.810 So we're going to say template and we create a new struct called t struct ops type traits and specify 04:13.810 --> 04:16.990 our custom gameplay effect context. 04:17.020 --> 04:24.430 That's for a gameplay effect context we're going to derive from t struct. 04:25.590 --> 04:27.240 Ops type traits. 04:27.240 --> 04:33.210 Base two and we're going to specify for a gameplay effect context. 04:33.210 --> 04:35.640 And if you want, you could place the public here. 04:35.640 --> 04:40.810 But it is redundant as writer will gray it out there. 04:40.830 --> 04:50.100 Now we define enum here and we need to set the enumerators with net serializer. 04:52.280 --> 04:58.130 Equal to true comma and with copy equal to true. 04:58.990 --> 05:06.570 And with that we have our struct ops type traits defined for our custom gameplay effect context. 05:06.580 --> 05:13.630 And that is a subtle yet very important detail that we need if we're going to have our own custom gameplay 05:13.630 --> 05:14.920 effect context. 05:14.920 --> 05:21.520 And with that, our gameplay effect context so far is looking complete. 05:22.490 --> 05:26.660 Now, I've already mentioned in a previous video that we can't just use this. 05:26.690 --> 05:33.450 We can't just expect that our project knows we want to use this class as our gameplay effect context. 05:33.470 --> 05:42.470 So what we'll learn how to do next is to designate the gameplay effect context struct project wide to 05:42.470 --> 05:46.700 be this one that gets used and then we'll learn how to utilize it. 05:47.030 --> 05:49.790 So excellent job and I'll see you soon. 05:50.780 --> 05:51.410 Hey there. 05:51.410 --> 05:52.910 It's Steven from the Future. 05:52.910 --> 05:58.010 And I'm back with just a slight update in Unreal Engine 5.3. 05:58.040 --> 06:05.320 We will actually get an error related to serializing our custom effect context. 06:05.330 --> 06:07.520 Now, the solution is quite simple. 06:07.550 --> 06:15.710 All we really need to do is make sure that our duplicate function here is set to return our custom type. 06:15.710 --> 06:22.880 That is our aura gameplay effect, context or whatever it is that you named. 06:22.880 --> 06:30.830 This particular struct mine is called aura gameplay effect context and the duplicate function should 06:30.830 --> 06:33.680 return a pointer to this type. 06:33.680 --> 06:37.910 So it should have f aura gameplay effect context in it. 06:37.910 --> 06:43.790 Now that also means that our new context local variable must be of this type. 06:43.790 --> 06:49.250 So when we use the new keyword we should use F aura gameplay effect context. 06:49.250 --> 06:57.540 And with this fix now we shouldn't get any problems serializing our custom gameplay effect context if 06:57.540 --> 06:59.520 we duplicate it with this function. 06:59.520 --> 07:08.910 Now, one other minor change is also that we need to return our static struct without fully qualifying 07:08.910 --> 07:10.920 the gameplay effect context. 07:10.950 --> 07:12.000 We don't need to do that. 07:12.000 --> 07:18.900 We can simply return static struct without fully qualifying the name there. 07:19.110 --> 07:25.950 This will not give us any errors when attempting to serialize this particular type. 07:25.950 --> 07:32.730 So just a couple of minor changes that we need in 5.3 and most likely beyond. 07:32.730 --> 07:34.620 So something to keep in mind. 07:34.620 --> 07:40.770 And if you check the repo for this lecture, you will see it still as the old way. 07:40.770 --> 07:45.330 But make sure you do it this new way so that you don't get any errors.