WEBVTT 00:06.860 --> 00:07.890 Welcome back. 00:07.910 --> 00:14.150 In this video, we're going to take a look at the effect context and make sure that we understand completely 00:14.150 --> 00:17.480 what's going on with the gameplay effect context. 00:17.510 --> 00:23.600 Now, the effect context is something that lives with a gameplay effect and seems to carry along some 00:23.600 --> 00:30.200 information, but thus far it isn't really all that clear to us exactly what information is being carried 00:30.200 --> 00:30.840 along. 00:30.860 --> 00:36.350 So we're going to take a deeper dive into the effect context in this video and see what it can do for 00:36.350 --> 00:43.190 us and find its limitations and start brainstorming about how we can get around those limitations. 00:43.220 --> 00:49.790 Now I'm here in the aura attribute set, set effect properties function, and we know that we have the 00:49.790 --> 00:52.370 effect context handle here. 00:52.370 --> 00:58.930 In this function, we're setting it on our props parameter, an input of type F effect properties. 00:58.940 --> 01:04.670 So here in set effect properties, we're setting that props dot effect context handle. 01:04.700 --> 01:11.340 By getting it from the effect spec which we have in our gameplay effect mod callback data so we can 01:11.340 --> 01:15.450 always get that effect context handle using get context. 01:15.600 --> 01:20.520 Now we know that the effect context handle has the effect context inside of it. 01:20.520 --> 01:25.080 So what I'd like to do is sort of pause execution right here. 01:25.110 --> 01:32.880 We can pause execution right here as soon as this property is being set and see exactly what that effect 01:32.880 --> 01:34.200 context has. 01:34.230 --> 01:37.740 By the time we've made it this far into the attribute set. 01:37.770 --> 01:38.850 So I'd like to do that. 01:38.850 --> 01:46.380 I'm going to click the debug button and what I think I'll do is launch a fireball as our fireball is 01:46.380 --> 01:47.760 applying a gameplay effect. 01:47.760 --> 01:49.950 It's our G damage effect. 01:49.950 --> 01:57.540 So I'd like to see basically what the context handle is carrying along by the time we apply that gameplay 01:57.540 --> 01:58.200 effect. 01:58.200 --> 02:04.110 So I'm going to press play and I'm going to come back into the editor and place a breakpoint here. 02:04.140 --> 02:11.400 I press play and then placed the breakpoint here just because I don't want to have to hit resume for 02:11.400 --> 02:12.990 the first time it gets called. 02:12.990 --> 02:16.740 So now that we have the game running, we have our breakpoint here. 02:16.830 --> 02:19.320 I'm going to launch a fireball at one of the enemies. 02:19.440 --> 02:26.010 And as soon as we apply that gameplay effect, we have our breakpoint reached and we have our effect 02:26.010 --> 02:27.810 context handle set. 02:27.840 --> 02:36.540 Now this has some data so we can take a look at it either by hovering over or taking a look down here 02:36.540 --> 02:38.160 at the bottom right. 02:38.400 --> 02:39.780 And we know that effect. 02:39.780 --> 02:47.610 Context handles have a data property and that data is the gameplay effect context itself. 02:47.610 --> 02:51.810 It's a shared pointer, but we can see all that the data has. 02:51.840 --> 02:58.110 And we're going to notice if we take a look at data and look at all the fields, we'll see that some 02:58.110 --> 03:01.740 of them are set and some of them are not set. 03:01.770 --> 03:06.870 A lot of these are empty or null pointer So what exactly is set? 03:06.870 --> 03:09.300 That's the first question we'd like to answer. 03:09.300 --> 03:11.180 And the second question is why? 03:11.190 --> 03:15.540 Why are those properties set and how come the others are not? 03:15.540 --> 03:18.630 So we're going to answer both of those questions in this video. 03:18.990 --> 03:23.580 So looking at these fields under data, we see that there's an instigator. 03:23.580 --> 03:27.630 And if we expand that, we can see what the instigator is. 03:27.660 --> 03:30.540 The instigator is an actor itself. 03:30.630 --> 03:38.010 We can see that it has a player state, an ability system component and an attribute set. 03:38.010 --> 03:39.600 And these seem to be set. 03:39.600 --> 03:42.930 So we have the BP or a player state here. 03:43.110 --> 03:47.190 We have the ability system component and attribute set. 03:47.710 --> 03:50.890 And we seem to see that there is a level set to one. 03:51.590 --> 03:58.130 We also see that there is an effect causer and the effect causer seems to be set to BP or a character. 03:58.130 --> 04:05.330 So something is setting our instigator to or a player state and the effect causer to or a character 04:05.330 --> 04:06.620 for some reason. 04:06.800 --> 04:14.000 And after these two instigator and effect causer, we have a bunch of other things that seem to be not 04:14.000 --> 04:15.080 set to anything. 04:15.080 --> 04:18.530 We have ability S.d.o set to null pointer. 04:18.560 --> 04:25.580 We have ability instance not replicated set to null pointer ability level seems to be set to one, but 04:25.580 --> 04:27.680 that must be some kind of default. 04:27.710 --> 04:31.250 We also have the source object and now we've seen source object before. 04:31.250 --> 04:35.630 We've set this before on our effect context for some of our effects. 04:35.660 --> 04:41.930 Now the effect that we're applying here that we currently have, we can tell what that effect is by 04:41.930 --> 04:43.610 hovering over effect spec. 04:43.610 --> 04:44.420 And here it is. 04:44.420 --> 04:46.580 It's GE damage, right? 04:46.580 --> 04:53.550 So we're applying GE damage and we know that we're creating the effect context in our projectile spell 04:53.550 --> 04:54.420 ability. 04:54.510 --> 05:03.090 So back to data here we see that source object is null instigator ability system component looks like 05:03.090 --> 05:04.260 that's being set. 05:04.260 --> 05:12.270 So that's one of the ones that is set actors looks like a t array of t weak object pointers. 05:12.300 --> 05:14.460 This array appears to be empty. 05:14.490 --> 05:17.100 We also have a hit result set to null. 05:17.100 --> 05:20.190 It's a pointer t shared pointer to a hit result. 05:20.220 --> 05:28.560 We have a world origin all zeroed out and for booleans has world origin replicate source object, replicate 05:28.560 --> 05:31.560 instigator and replicate effect causer. 05:31.560 --> 05:37.500 And we're going to see exactly why these have the values that they have here as well. 05:37.590 --> 05:42.720 So the first question is what's setting these properties that are set? 05:42.750 --> 05:46.250 We know that source object won't be set unless we set it ourselves. 05:46.260 --> 05:47.520 We've done that before. 05:47.520 --> 05:54.210 But instigator effect, causer and instigator ability system component seem to be getting set somehow. 05:54.210 --> 05:56.520 So it's time to investigate. 05:56.520 --> 05:59.640 So I'm going to hit stop and we're going to answer these questions. 05:59.640 --> 06:04.800 Now, the first thing we should look at is where we're creating the effect context that we just looked 06:04.800 --> 06:05.400 at. 06:05.460 --> 06:11.430 We can go to private ability system abilities and open aura projectile spell. 06:11.460 --> 06:15.690 I'm going to go ahead and close all tabs and open aura projectile spell. 06:15.690 --> 06:22.950 And here we can see where we're making the effect context for our G damage effect we're applying here. 06:22.980 --> 06:27.690 We see that we're calling make outgoing spec, which requires the effect context. 06:27.690 --> 06:33.840 And for that context we're passing in whatever we get returned from make effect context. 06:33.840 --> 06:39.330 So whatever make effect context is doing for us, whatever it's setting by default, that's what we're 06:39.330 --> 06:41.760 getting and we've seen what it's doing for us. 06:41.760 --> 06:48.600 We've seen that it's set the effect causer and instigator as well as instigator ability system component 06:48.600 --> 06:53.970 so we can investigate what this function is doing exactly by peeking that definition. 06:53.970 --> 06:56.250 I'm going to go to the definition for it. 06:56.430 --> 06:57.660 Here it is. 06:57.660 --> 07:05.310 And we see that it's making a context handle using the gameplay effect context, handle constructor 07:05.310 --> 07:09.390 and passing in whatever is returned from this function. 07:09.390 --> 07:14.460 U ability system globals Alec Gameplay effect Context. 07:14.490 --> 07:15.990 Now this is pretty simple. 07:15.990 --> 07:20.160 If we go to this declaration, we see that it's just calling new here. 07:20.160 --> 07:21.630 That's all that it's doing. 07:21.990 --> 07:26.730 Really nice function ability system globals, lots of hard work you're doing for us. 07:26.730 --> 07:33.090 So that's what it's doing and it's passing that into the constructor, creating a new context. 07:33.090 --> 07:37.710 It's taking the ability actor info, which is a member variable of this class. 07:37.710 --> 07:38.870 What class are we in? 07:38.880 --> 07:40.740 We're in the ability system component. 07:40.760 --> 07:43.440 That's where make effect context is. 07:43.440 --> 07:48.900 So we're checking that this ability system components, ability actor info is valid here. 07:48.900 --> 07:53.340 So in other words, we can't make an effect context if we don't have valid info. 07:53.340 --> 07:57.210 And then we're taking that context and calling add instigator. 07:57.210 --> 08:05.190 So the gameplay effect context handle class has this add instigator and it looks like it takes two inputs 08:05.220 --> 08:08.400 in instigator and in effect causer. 08:08.610 --> 08:15.690 And for the instigator input parameter, we're getting our ability actor info and getting the owner 08:15.690 --> 08:20.370 actor from it for the effect causer to this function. 08:20.370 --> 08:24.960 The second input we're passing in ability actor info Avatar actor. 08:24.960 --> 08:30.270 So this is why those properties are set because we're calling add instigator and then this function 08:30.270 --> 08:32.310 simply returns the context. 08:32.310 --> 08:34.920 So let's see what Add instigator is doing for us. 08:34.920 --> 08:42.180 I'm going to go to that definition, and this is a function on the effect context handle, right? 08:42.180 --> 08:49.740 So it makes sense that the effect context handle is going to reach into its own data property and simply 08:49.770 --> 08:51.060 set something on that. 08:51.060 --> 08:51.180 So. 08:51.260 --> 08:57.370 Was just calling an instigator, passing in those inputs that we passed in to add instigator. 08:57.370 --> 09:03.190 So what does the effect context class itself do when calling add instigator? 09:03.190 --> 09:07.990 Let's go one level deeper and here we can see that it's doing a few things. 09:08.080 --> 09:14.980 For one, the gameplay effect context is setting a member variable instigator to the instigator passed 09:14.980 --> 09:15.130 in. 09:15.130 --> 09:17.230 Remember what was passed into this? 09:17.230 --> 09:17.770 Right? 09:17.770 --> 09:22.360 We can see by going to the ability system component make effect context, we can see that we're passing 09:22.360 --> 09:24.250 in the owner actor. 09:24.250 --> 09:30.370 So if this were, say, Aura's ability system component, this would be the player state. 09:30.370 --> 09:37.060 And of course for the second input parameter, that Avatar actor is the aura character itself, right? 09:37.210 --> 09:43.420 So we can see here that we're setting the instigator on the effect context to this in instigator, which 09:43.450 --> 09:45.850 for Aura's case is going to be the player state. 09:46.000 --> 09:53.230 Now it's also calling can actor reference be replicated passing that instigator in and if we scroll 09:53.230 --> 09:58.900 up just a little bit we can see that function and how it's determining the result of this. 09:58.900 --> 10:05.200 It's taking the actor making sure it isn't null it's calling is full name stable for networking which 10:05.200 --> 10:07.570 dig deeper if you want to see what that does. 10:07.570 --> 10:10.840 And then it's seeing if the actor is supported for networking. 10:10.840 --> 10:16.510 Again, dig deeper if you want to see what that does, and it also checks to see if the actor is replicated. 10:16.510 --> 10:22.390 So it's doing a few things and after it calls that function, it sets a boolean on the effect context 10:22.390 --> 10:24.160 called replicate instigator. 10:24.160 --> 10:29.920 So this is how it determines that that instigator is a replicated variable. 10:29.920 --> 10:33.280 Now that is why we saw that particular boolean. 10:33.280 --> 10:38.890 I don't know if you looked at those values, but this particular boolean is definitely set, right? 10:38.890 --> 10:45.310 So those two properties on the effect context are already set just from us making one. 10:45.310 --> 10:47.920 Now it also has set effect causer. 10:47.920 --> 10:55.340 If we peek the definition of this, we can see that set effect causer is setting the effect causer variable. 10:55.340 --> 11:02.000 So apparently the gameplay effect context has an effect causer and then it's setting this be replicate 11:02.000 --> 11:07.970 effect causer and it's calling that same function that determines whether or not that actor is a replicated 11:07.970 --> 11:08.330 actor. 11:08.330 --> 11:13.730 So we have that also set for us that explains why that property is set. 11:13.730 --> 11:20.330 So the instigator in effect causer, those are set by default for us just by making an effect. 11:20.330 --> 11:21.380 Context. 11:21.470 --> 11:26.660 Now the gameplay effect context has an instigator ability system component pointer. 11:26.660 --> 11:28.820 It's a weak object pointer. 11:28.820 --> 11:32.030 These are all weak object pointers and we'll see why in a second. 11:32.060 --> 11:39.590 And what it does is it first nulls it out before using ability system globals and calling get ability 11:39.590 --> 11:45.740 system component from actor a ability system globals function and then it sets that instigator ability 11:45.740 --> 11:47.180 system component to that. 11:47.180 --> 11:51.290 So that's another property that was already set for us. 11:51.290 --> 11:58.400 So this add instigator function sets those properties for us and that's why in aura projectile spell, 11:58.400 --> 12:03.650 just calling make effect context results in those properties being set. 12:03.650 --> 12:10.070 And that's why we saw those when we placed a breakpoint and paused execution right there in our attribute 12:10.070 --> 12:10.610 set. 12:10.880 --> 12:15.290 Okay, so we've seen why those properties that were set are set. 12:15.290 --> 12:18.860 That's because make effect context sets those for us. 12:18.860 --> 12:22.070 So the question is, what about all those other properties? 12:22.070 --> 12:26.900 How come make effect context doesn't just fill in the whole effect context? 12:26.930 --> 12:31.580 Well, the effect context doesn't necessarily need to be fully filled out. 12:31.580 --> 12:33.950 It doesn't need all of its properties filled out. 12:33.950 --> 12:41.630 But there are other variables in the effect context struct that we could set if we wanted to notice 12:41.630 --> 12:46.760 that the effect context constructor sets the ability level to a default value of one. 12:46.760 --> 12:52.460 That's why we saw that one when we were checking out that effect context. 12:52.490 --> 12:59.660 We see that world origin is forced to zero force in it to zero and we have booleans that are set to 12:59.660 --> 13:00.620 false here. 13:01.130 --> 13:07.700 Now the effect context also has a constructor that can take in an instigator and effect causer. 13:07.700 --> 13:14.990 And all that really does is zeros out and falses out some of these properties and then calls add instigator. 13:14.990 --> 13:17.840 So we've seen what Add instigator does for us. 13:17.840 --> 13:21.140 So nothing really too spectacular there. 13:21.320 --> 13:24.350 So let's take a look at what else the effect context has. 13:24.350 --> 13:31.490 It has a virtual void Get owned gameplay tags which says returns a list of gameplay tags applicable 13:31.490 --> 13:37.160 to this object, defaults to the owner's tabs and we can always take a look at this. 13:37.160 --> 13:44.930 Get owned gameplay tags function if we want and we can see that it casts the instigator to an AI gameplay 13:44.930 --> 13:51.190 tag asset interface, which does have a couple of functions for getting owned gameplay tags in fact. 13:51.350 --> 13:53.570 It has jet owned gameplay tags. 13:53.570 --> 14:00.710 So what this function does is it sees if the instigator implements the gameplay tag asset interface 14:00.710 --> 14:03.080 and calls, get own gameplay tags on it. 14:03.110 --> 14:08.570 Otherwise, if it doesn't implement that interface, we just get the instigator ability system component 14:08.570 --> 14:11.030 and then get own gameplay tags from that. 14:11.030 --> 14:14.060 So that's all that get own gameplay tags does for us. 14:14.090 --> 14:15.200 Add instigator. 14:15.200 --> 14:16.780 We've seen what that does. 14:16.790 --> 14:18.280 What about set ability? 14:18.290 --> 14:20.150 Let's take a look at set ability. 14:20.920 --> 14:21.850 So here we go. 14:21.850 --> 14:29.530 It's checking the ability that we pass in so it takes one in by a const pointer and then it sets three 14:29.530 --> 14:31.570 variables on the effect context. 14:31.570 --> 14:35.170 So set ability sets, ability instance not replicated. 14:35.170 --> 14:37.240 And what is it setting it with? 14:37.240 --> 14:41.830 Well, it's taking the ability passed in and it's performing a const cast. 14:41.860 --> 14:45.880 We've seen what const casts do in previous sections. 14:45.880 --> 14:50.170 The const cast casts away the const ness. 14:50.200 --> 14:56.950 That's kind of a tongue twister, but we're passing in a const pointer, const, cast, un const. 14:56.980 --> 14:57.370 It. 14:57.370 --> 15:03.370 It casts away the constness and then the function makes a weak object pointer and then sets ability 15:03.370 --> 15:06.100 instance not replicated to that. 15:06.100 --> 15:09.550 So basically this is just a setter for this variable. 15:09.550 --> 15:11.510 It also sets the ability cd0. 15:11.680 --> 15:18.220 So it's taking this game play ability, calling Getclass on it and calling get default object on it. 15:18.220 --> 15:22.510 And this is going to return the class default object for that CDO. 15:22.520 --> 15:26.270 And then we're calling it ability level and setting ability level. 15:26.270 --> 15:29.840 So that sets that property on the effect context. 15:29.840 --> 15:33.320 So set ability sets these three properties for us. 15:33.560 --> 15:36.320 Moving on, we have a getter for the instigator. 15:36.380 --> 15:39.830 It just calls get on the instigator and returns it. 15:39.860 --> 15:47.330 We have a get ability function and if we go to this definition, we see that it does basically the same 15:47.330 --> 15:47.540 thing. 15:47.540 --> 15:50.990 It gets the ability CDO calls get on it. 15:50.990 --> 15:57.110 So why get instigator is defined here but get ability is defined in the CPP file. 15:57.290 --> 15:58.430 Who knows? 15:58.430 --> 16:04.940 I can only imagine it's because this has been worked on by multiple people and some people have different 16:04.940 --> 16:05.870 styles. 16:05.870 --> 16:07.760 So we've seen what get ability does. 16:07.760 --> 16:13.070 We have get ability instance not replicated, which as you can imagine going to the definition, we 16:13.070 --> 16:16.280 can see that it just calls get on that variable. 16:16.280 --> 16:19.730 We also have ability level just returns the ability level. 16:19.730 --> 16:25.760 We also have a getter for the ability system component of the instigator, also for the effect causer. 16:25.760 --> 16:28.070 And then we have a setter for the effect causer. 16:28.070 --> 16:33.770 And by setting the effect causer, we see that we're setting be replicate effect causer so we don't 16:33.770 --> 16:35.660 have to set that manually. 16:35.690 --> 16:38.420 This setter is going to take care of that for us. 16:38.450 --> 16:42.050 Get original instigator is just going to return the instigator. 16:42.050 --> 16:43.250 That's all it does. 16:43.280 --> 16:44.390 This is virtual. 16:44.390 --> 16:50.030 So keep in mind that the virtual versions of these can be overridden if we subclass this. 16:50.180 --> 16:56.390 So again, some more getters we've seen what Add source object does and there's a getter for that. 16:56.420 --> 17:03.410 Now add actors is interesting because it takes in a array of weak object pointers to actors and there's 17:03.410 --> 17:07.250 a B reset that has the default value of false. 17:07.250 --> 17:15.500 So basically add actors is going to check be reset and make sure that the actors array passed in isn't 17:15.500 --> 17:22.160 empty and it's going to reset the array so it'll be emptied out and then actors will have this array 17:22.160 --> 17:23.090 tacked on to it. 17:23.090 --> 17:28.460 So in effect, context has an array of actors that can be set for any reason. 17:28.460 --> 17:35.060 So if you have an effect and you want to stick an array of actors into it, you can stick that in the 17:35.060 --> 17:36.380 gameplay effect context. 17:36.380 --> 17:39.500 And then later on down the pipeline you can access it. 17:39.500 --> 17:45.920 Same thing with the hit result and there's an add hit result that allows you to reset the hit result 17:45.920 --> 17:47.420 with an optional boolean. 17:47.420 --> 17:54.680 And if you do pass in true for that it'll reset the hit result and also set has world origin to false 17:54.680 --> 18:00.110 and then it takes that hit result and sets the hit result variable to that. 18:00.110 --> 18:02.870 And this is creating a shared pointer. 18:02.870 --> 18:08.210 So the effect context stores the hit result as a pointer and we'll see why very shortly. 18:08.210 --> 18:16.340 But if we've reset that hit result, then it's going to add the world origin and add origin. 18:16.340 --> 18:21.560 It's just going to set this world origin vector equal to that hit result trace start. 18:21.710 --> 18:27.530 And then we have net serialize and we're going to talk more about net serialize in a future video when 18:27.530 --> 18:31.070 we have to create some of this stuff on our own. 18:31.070 --> 18:40.130 But this just specifies how this gameplay effect context struct will be serialized when it has to be 18:40.130 --> 18:41.690 sent across the network. 18:41.690 --> 18:49.760 And lastly, we have a to string which really just gets the instigator and returns its name if it's 18:49.760 --> 18:51.980 not null, otherwise it returns none. 18:51.980 --> 18:59.450 And we have a is locally controlled effect context which checks the instigator casts it to a pawn and 18:59.450 --> 19:06.650 if the pawn cast fails, it then tries to cast the effect causer to a pawn and sets that to this local 19:06.650 --> 19:07.670 pawn variable. 19:07.670 --> 19:12.410 And if that's valid, then it calls is locally controlled on that pawn. 19:12.410 --> 19:14.210 So it first tries the instigator. 19:14.210 --> 19:16.880 If that fails, then it tries the effect causer. 19:16.910 --> 19:20.450 If that fails, this function returns false. 19:20.790 --> 19:27.180 And if it doesn't fail, we return is locally controlled on the Pon is locally controlled player does 19:27.180 --> 19:33.090 the same thing, except it then takes the pawn and gets its controller and then calls is local player 19:33.090 --> 19:34.080 controller. 19:34.080 --> 19:41.190 Here's the Add origin which just sets this world origin variable, which happens to be an f vector equal 19:41.190 --> 19:43.260 to whatever we pass in here and then it sets. 19:43.260 --> 19:46.470 This B has world origin boolean to true. 19:46.830 --> 19:50.010 Now we've seen get owned gameplay tags, we know what that does. 19:50.040 --> 19:54.630 And after that, in this file we see net serialized for the context handle. 19:54.630 --> 19:57.360 So we're starting to see things for the context handle. 19:57.360 --> 20:04.140 So at this point we've seen all of the gameplay effect, context, struct and now we know the types 20:04.140 --> 20:09.360 of information that can be stored on it if we want to pass that information along. 20:09.360 --> 20:11.550 So that's pretty cool. 20:11.550 --> 20:17.760 We can create one of these in or a projectile spell and fill it in with more data if we'd like, and 20:17.760 --> 20:23.980 then test this system out, see what those values are equal to in our attribute set. 20:24.010 --> 20:25.480 If we like to do that. 20:25.480 --> 20:32.500 And then we'll go ahead and wrap this video up and discuss possible ways to make our effect context 20:32.500 --> 20:34.030 even more useful. 20:34.030 --> 20:38.560 If we'd like to pass along more interesting data that doesn't exist in it yet. 20:38.560 --> 20:44.890 So rather than calling make effect context right here and make outgoing spec directly, I'd like to 20:44.890 --> 20:46.990 make an effect context right here. 20:47.260 --> 20:55.120 So this will be an F gameplay effect context and actually this is a context handle that we need to make. 20:55.120 --> 21:02.920 So we're going to make effect, context, handle and set it equal to the result of source ask, make 21:02.950 --> 21:04.300 effect context. 21:04.930 --> 21:11.830 And now we have an effect context handle that we can pass in right here into the function make outgoing 21:11.860 --> 21:18.070 spec and now that we have an effect context handle, let's think about the different properties on here 21:18.070 --> 21:19.510 that we can pass along. 21:19.510 --> 21:26.470 So back to gameplay effect types, let's scroll down a little bit to the variables that exist in this 21:26.470 --> 21:27.040 class. 21:27.040 --> 21:28.450 They're all protected. 21:28.600 --> 21:31.600 And let's take a look at this comment right here. 21:31.600 --> 21:34.930 It says, The object pointers here have to be weak. 21:34.930 --> 21:42.220 So weak object pointers because contexts aren't necessarily tracked by garbage collection in all cases. 21:42.280 --> 21:46.120 Now, it would help if you understood what a weak object pointer does. 21:46.600 --> 21:48.880 Weak object pointers are smart pointers. 21:48.880 --> 21:57.190 They're wrappers that can store pointers and a weak object pointer has the property of not taking ownership 21:57.190 --> 22:00.070 of the pointer that it stores. 22:00.070 --> 22:04.150 In other words, it does not participate in reference counting. 22:04.150 --> 22:13.000 You see, smart pointers are reference counted as soon as an object no longer has any references to 22:13.000 --> 22:17.350 it, any pointers that point to it, it's automatically deleted. 22:17.350 --> 22:20.230 That's why smart pointers are useful now. 22:20.260 --> 22:27.160 Weak object pointers have the property of not being reference counted, so reference counting to delete 22:27.160 --> 22:33.850 an object or extend its lifetime for that matter is not affected by a weak object pointer. 22:34.030 --> 22:40.630 And the reason these are weak pointers is because well, it says right here not all effect contexts 22:40.630 --> 22:43.390 are necessarily tracked by garbage collection. 22:43.960 --> 22:47.290 In fact, ours is not here in or a projectile spell. 22:47.290 --> 22:48.880 This is a local variable. 22:48.880 --> 22:51.610 It's not tracked by garbage collection. 22:51.760 --> 22:57.070 And here we can see our different properties and we already know about these. 22:57.070 --> 23:01.090 But here are some useful comments that give us more information. 23:01.090 --> 23:02.080 Here's the instigator. 23:02.080 --> 23:06.910 It says instigator actor, the actor that owns the ability system component. 23:07.090 --> 23:10.540 And we've seen that this gets set for us automatically. 23:10.540 --> 23:16.750 And in the case of Aura, we saw that it was set to the player state which owns our aura ability system 23:16.750 --> 23:17.260 component. 23:17.260 --> 23:18.340 So that's correct. 23:18.370 --> 23:24.610 The effect causer is the physical actor that actually did the damage can be a weapon or a projectile. 23:24.610 --> 23:30.010 In our case it was aura because that was set to the avatar actor. 23:30.280 --> 23:36.610 We have the ability CDO that says the CDO that is responsible for this effect context in parentheses 23:36.610 --> 23:37.690 replicated. 23:37.870 --> 23:41.860 So we've seen that there are different instancing policies for gameplay abilities. 23:41.860 --> 23:44.120 Some are instanced, some are not. 23:44.120 --> 23:52.190 And the class default object is we've seen the result of that get default object function call. 23:52.430 --> 23:56.780 The ability instance not replicated is a pointer to a gameplay ability. 23:56.960 --> 24:03.140 It specifically has the not replicated value property and it says the ability instance that is responsible 24:03.140 --> 24:05.360 for this effect context not replicated. 24:05.360 --> 24:08.390 So we have replicated and not replicated. 24:08.390 --> 24:12.530 We've seen that the ability level is just set to one by default. 24:12.560 --> 24:19.730 We've seen the source object and we can set that, although now we know that if we set this equal to, 24:19.760 --> 24:24.920 say, the Avatar actor, well, we already know that the effect causer is set to that. 24:24.920 --> 24:27.320 So that would be redundant, wouldn't it? 24:27.350 --> 24:33.050 The ability system component that's bound to the instigator is the instigator ability system component. 24:33.050 --> 24:34.970 We've seen that that is set for us. 24:34.970 --> 24:37.040 It's not replicated as well. 24:37.310 --> 24:42.920 We have a array of weak object pointers to actors, which is empty. 24:42.920 --> 24:45.020 We've seen that nothing happens to this array. 24:45.020 --> 24:48.680 It's not set, but it says actors referenced by this context. 24:48.680 --> 24:50.840 So that's for whatever reason we want. 24:50.870 --> 24:52.040 Same for this hit result. 24:52.040 --> 24:54.920 It just has a hit result right there for us. 24:54.950 --> 24:59.390 It says trace information may be null pointer In many cases, yes. 24:59.390 --> 25:04.760 In all cases unless we set it same with the world origin if we set the hit result. 25:04.760 --> 25:09.560 Interestingly the world origin will be set to the trace start of that hit result. 25:09.560 --> 25:14.750 And then we have these Uint eight which are treated like booleans. 25:14.750 --> 25:16.160 We call this a bit field. 25:16.160 --> 25:26.210 Essentially this guarantees that a bit array of contiguous bits will be populated by these variables 25:26.210 --> 25:32.090 which can be checked as if they're booleans, they can be treated like booleans, but they just take 25:32.090 --> 25:34.220 up a single bit altogether. 25:34.220 --> 25:38.690 They all take up at least a minimum of eight bits in a row. 25:38.690 --> 25:45.620 So just because there's four of them here doesn't mean that it only takes up four bits at least one 25:45.650 --> 25:53.480 uint, eight worth of memory is taken, but this allows us to not have one, two, three, four booleans, 25:53.480 --> 25:55.670 each of which would be one byte. 25:55.700 --> 25:57.110 A byte is eight bits. 25:57.110 --> 26:01.790 So as you can see, this is a good deal smaller than using booleans. 26:01.790 --> 26:03.320 It's just an optimization. 26:03.320 --> 26:08.570 Sometimes you'll see it in the engine, sometimes you may even use it yourself and that's it. 26:08.570 --> 26:10.400 That's all of these properties. 26:10.400 --> 26:15.770 And just for fun, let's set some of these, at least the ones we know that aren't already set. 26:15.800 --> 26:22.700 We know instigator and effect causer are already set, and if we want to jog our memories, we can go 26:22.700 --> 26:30.950 back into the attribute set and we can run in debug mode and pause execution right here and see exactly 26:30.950 --> 26:33.950 which properties are not already set for us. 26:36.760 --> 26:37.030 Okay. 26:37.030 --> 26:38.260 I'm going to press play. 26:38.870 --> 26:44.240 Before I launch a fireball, I'm going to place that breakpoint and then launch the fireball. 26:46.260 --> 26:50.190 And let's take a look at our effect context in the handle. 26:50.220 --> 26:55.830 Here's data We know that instigator is set effect causer is set ability. 26:55.860 --> 27:03.480 CTO is not set, but we saw that this could be set automatically if we go into gameplay effect types 27:03.480 --> 27:09.240 and scroll up a bit, we can see that set ability will set ability for us. 27:09.240 --> 27:14.400 So all we need to do is pass in a new gameplay ability into set ability. 27:14.760 --> 27:23.640 So right here in aura projectile spell, we can take our effect context handle and call set ability 27:23.640 --> 27:28.830 and we can pass in the ability well we're inside of our ability or a projectile spell. 27:28.830 --> 27:35.760 So if we pass in this then set ability will take that pointer and what's it going to do with it. 27:35.760 --> 27:40.200 It's going to set ability instance, not replicated ability. 27:40.590 --> 27:43.200 Oh, and even ability level. 27:43.200 --> 27:46.780 So just calling that takes care of three of those. 27:46.960 --> 27:47.350 Okay. 27:47.350 --> 27:52.600 So back to aura attribute set, let's go back to looking at the data here. 27:52.600 --> 27:55.810 We know that ability will be set for us. 27:55.840 --> 27:59.860 So will ability instance not replicated and ability level. 27:59.860 --> 28:01.420 What about source object? 28:01.420 --> 28:03.370 Well, we've seen that before. 28:03.370 --> 28:08.770 We were setting this to the avatar, but that's actually what effect Causer is set to, isn't it? 28:08.770 --> 28:14.110 So if we wanted to, we can set the source object to the avatar. 28:14.110 --> 28:18.550 We could also set it to anything that we'd like to call the source object. 28:18.550 --> 28:26.200 If we go back to Aura projectile spell, we could even set the source object to the projectile itself 28:26.200 --> 28:28.840 so we could take effect. 28:28.840 --> 28:35.200 Context handle call add source object and pass in projectile. 28:36.300 --> 28:39.450 Let's go back and look at our data here. 28:40.430 --> 28:43.460 So we see that we're now going to be setting the source object. 28:43.490 --> 28:47.750 We know that instigator ability system component is set. 28:47.780 --> 28:49.350 What about the actor's array? 28:49.370 --> 28:55.460 Well, at this point, we're just kind of filling things in because we can I don't know if Aura Projectile 28:55.460 --> 29:03.350 spell really has really enough actors to add to the array, but if we like, we could we could take 29:03.350 --> 29:10.610 effect context, handle dot add actors and we could pass in a T array. 29:10.640 --> 29:12.860 We could make a T array. 29:13.520 --> 29:16.340 And we know this is t week object pointers. 29:17.930 --> 29:21.530 And the type is a actor. 29:23.350 --> 29:25.480 We can make this actors here. 29:27.490 --> 29:29.680 And we could add something to the actors. 29:29.680 --> 29:30.900 What are we going to add? 29:30.910 --> 29:32.380 Anything we want. 29:33.610 --> 29:38.290 I'll just pass in projectile just because I can and pass actors in. 29:40.400 --> 29:40.760 Okay. 29:40.760 --> 29:41.630 What else can we set? 29:41.660 --> 29:44.480 We're running out of things here, but let's just see. 29:44.480 --> 29:46.640 We have a hit result right now. 29:46.640 --> 29:47.600 A hit result. 29:47.630 --> 29:50.660 This is a shared pointer to a hit result. 29:50.660 --> 29:52.670 So how are we going to set that? 29:52.670 --> 29:56.860 Well, we've seen how it was done in gameplay effect types. 29:56.870 --> 30:01.820 We can see that it's making a shared pointer here and storing that in hit result. 30:01.820 --> 30:06.260 But add hit result just takes in a hit result and an optional boolean. 30:06.260 --> 30:16.010 So we could just pass one in f hit result hit result and take the effect context handle dot add hit 30:16.010 --> 30:16.760 result. 30:18.300 --> 30:23.580 And pass in hit results, which we know is empty anyway. 30:24.060 --> 30:24.500 Okay. 30:24.510 --> 30:30.360 Looking at data, world origin will be set because we're adding a hit result and then the rest of these 30:30.360 --> 30:33.360 will be set as a result of setting the others. 30:33.360 --> 30:37.980 So we basically set all we can here on this effect context handle. 30:37.980 --> 30:41.100 And really a lot of these are just kind of silly. 30:41.100 --> 30:48.030 We're just adding them because we can, but this allows us to check to see if that information is being 30:48.030 --> 30:49.170 passed along. 30:49.500 --> 30:57.270 So just to prove that this hit result is working, we're going to take hit result dot location and set 30:57.270 --> 30:59.670 that because we do have that here. 30:59.670 --> 31:01.740 It's the projectile target location. 31:01.740 --> 31:04.320 We'll set that location here in the hit result. 31:04.350 --> 31:05.070 Why not? 31:05.700 --> 31:11.940 So now we can run in debug mode and just see how much of this data we can take a look at by placing 31:11.940 --> 31:12.690 a breakpoint. 31:14.670 --> 31:14.910 Okay. 31:14.910 --> 31:16.110 I'm going to press play. 31:17.710 --> 31:23.120 I'm going to stick a breakpoint in the attribute set after we get the effect context handle. 31:23.140 --> 31:24.760 I'm going to launch a fireball. 31:25.790 --> 31:28.520 And we're going to hover over context handle. 31:29.010 --> 31:31.230 And take a look at the data here. 31:31.380 --> 31:34.560 And we're going to see that we have a lot more information. 31:34.860 --> 31:41.790 First of all, the four booleans down here all have true or one set for their value. 31:41.790 --> 31:46.110 Here we see that the instigator is set to or a player state. 31:46.140 --> 31:52.350 The effect causer is set to or a character the ability CTO is set to default to firebolt. 31:52.380 --> 31:55.590 Now we have access to the class here. 31:55.590 --> 32:00.540 We've seen how much we can get information from the class default object. 32:00.540 --> 32:04.110 And because this is a firebolt, it has a projectile class. 32:04.110 --> 32:05.670 That's the firebolt there. 32:05.910 --> 32:08.460 We have the ability instance not replicated. 32:08.460 --> 32:10.650 There's that Firebolt ability instance. 32:10.650 --> 32:15.420 We have the ability level now set to the actual level of the ability. 32:15.420 --> 32:16.650 Here's the source object. 32:16.650 --> 32:22.590 We set that to the projectile itself and we can see that that's Bpy Firebolt cool. 32:22.590 --> 32:26.310 And there are lots of properties that we have access to there. 32:26.310 --> 32:31.390 Now here's the instigator ability system component that's set actors. 32:31.390 --> 32:38.260 We have an array and if we take a look the Firebolt itself, we added that projectile to that actor's 32:38.290 --> 32:39.800 array just because we could. 32:39.820 --> 32:40.990 Here's the hit result. 32:40.990 --> 32:43.090 And if we take a look at the location. 32:43.120 --> 32:48.400 Here's the location we passed through the location of the projectiles target. 32:48.400 --> 32:49.480 So that's there. 32:49.480 --> 32:52.960 And it looks like world origin was set to zero. 32:52.960 --> 32:55.420 That's because it was taken from that hit result. 32:55.420 --> 32:58.090 And that's not something that we set on the hit result. 32:58.090 --> 33:03.910 And then, of course, these four booleans, we've seen that setting these properties with the setters 33:03.940 --> 33:09.190 results in the effect context, setting these properties for us automatically. 33:09.370 --> 33:10.240 Okay, cool. 33:10.240 --> 33:18.550 So now we've seen basically the extent of the usefulness of the gameplay effect context struct, and 33:18.550 --> 33:21.550 it probably has more inside of it than you realized. 33:21.550 --> 33:22.240 Right? 33:22.270 --> 33:27.940 It's good to know about all these things because it's better to take advantage of what's already there 33:27.940 --> 33:35.020 rather than trying to add more code to do something that you want to do if you needed to do something 33:35.020 --> 33:35.980 in addition to this. 33:35.980 --> 33:38.710 But there are some limitations, right? 33:38.740 --> 33:42.880 What if we want to send across information that's not in here? 33:43.180 --> 33:50.800 For one, I'd like to know in my aura attribute set by the time we get to post gameplay effect, execute 33:50.830 --> 33:56.410 whether or not we got a critical hit, whether or not we got to block our gameplay effect. 33:56.410 --> 34:01.120 Context doesn't have a boolean here for whether it was a critical hit. 34:01.120 --> 34:04.840 It does not have a boolean for whether it was a block. 34:05.260 --> 34:08.680 So those are limitations of the effect context. 34:08.950 --> 34:12.490 It doesn't have custom things that we want inside of it. 34:12.520 --> 34:20.040 However, it has a lot of virtual functions which seems to indicate that we could subclass this struct 34:20.050 --> 34:28.300 and that is what I'd like to do in the videos to come so that we can have even more information set 34:28.300 --> 34:30.460 in our gameplay effect context. 34:30.460 --> 34:34.510 So that's what's on the menu and we'll get into that in the videos to come. 34:34.510 --> 34:42.790 So nice informative video, great job sticking through with all of our investigations and studying of 34:42.790 --> 34:45.190 how this class works and what it does. 34:45.220 --> 34:48.160 And I'll see you in the next video.