WEBVTT 00:06.840 --> 00:08.220 Welcome back. 00:08.550 --> 00:14.460 So we know that we're applying a gameplay effect whenever we launch a fireball and that gameplay effect 00:14.460 --> 00:19.170 is going to result in subtracting from the health of the enemy. 00:19.500 --> 00:26.220 Now that we know about damage meta attributes, we're going to use a meta attribute for damage rather 00:26.220 --> 00:31.050 than having our gameplay effect reach in and change the health directly. 00:31.290 --> 00:39.810 So if I go to blueprints ability system gameplay effects and go to my G damage and scroll down, we'll 00:39.810 --> 00:44.610 see that this is an instant gameplay effect set to subtract ten from the health. 00:44.760 --> 00:48.440 So this is very much a placeholder gameplay effect, right? 00:48.450 --> 00:51.020 It's hard coding negative ten. 00:51.030 --> 00:56.940 We're not even using a curve table or anything like that and we're setting the health, but we'd like 00:56.940 --> 01:04.860 to modify the meta attribute and then allow the attribute set to go through any processing of that data 01:04.860 --> 01:06.210 that we'd like it to do. 01:06.210 --> 01:12.670 And we'd also like to use that damage meta attribute in any of our custom calculations as well. 01:12.670 --> 01:19.780 We can change this to a custom calculation class, for example, as damage is going to be one of the 01:19.780 --> 01:22.960 more complicated types of modifiers. 01:23.080 --> 01:28.720 So anyway, we'd like a damage meta attribute and for that we're going to close the editor and head 01:28.720 --> 01:31.090 back over to our attributes set. 01:31.210 --> 01:33.640 So I'm going to open my attribute set. 01:33.640 --> 01:42.190 I'm also going to close other tabs and get my header and CPP files open here and here in my Aura attribute 01:42.190 --> 01:49.570 set, we're going to create a new attribute and this one will be our first meta attribute. 01:49.570 --> 01:56.920 So just below vital attributes, I'm going to make a multi-line comment that says meta attributes. 01:58.190 --> 02:00.080 And we'll have our first one. 02:00.080 --> 02:07.520 So we'll have a gameplay attribute data called Incoming Damage. 02:07.760 --> 02:15.890 And incoming damage is going to get a new property, but it's not going to get replicated. 02:15.890 --> 02:20.720 It will not get a rep notify as meta attributes are not replicated. 02:20.720 --> 02:27.710 We set them on the server and then on the server we process the data and then change any replicated 02:27.710 --> 02:28.340 attributes. 02:28.340 --> 02:35.360 Based on those calculations, we can make it blueprint read only though and we'll give it a category. 02:35.360 --> 02:43.910 But the category is going to be meta attributes and we can make attribute accessors. 02:43.910 --> 02:52.820 So let's go ahead and use our attribute accessors macro passing in you ora attribute set and incoming 02:52.820 --> 02:53.630 damage. 02:54.180 --> 02:57.710 So that takes care of making the meta attribute. 02:57.720 --> 03:00.720 So how do we actually use the meta attribute? 03:00.750 --> 03:03.000 That's the next thing we'd like to handle. 03:03.000 --> 03:13.050 So let's go into our CPP file and we'll go to post gameplay effect, execute right here and here we 03:13.050 --> 03:21.420 can actually check to see if the evaluated data has the attribute incoming damage and then we can respond 03:21.420 --> 03:22.350 accordingly. 03:22.590 --> 03:31.200 So down here at the bottom we'll just place an If check and say if data dot evaluated data dot attribute 03:32.070 --> 03:37.260 equals and we'll use get incoming damage attribute. 03:38.010 --> 03:42.600 So here we know that we're actually getting a change to incoming damage. 03:42.630 --> 03:51.270 Now incoming damage being a meta attribute should be used for its value and then reset or zeroed out. 03:51.270 --> 03:53.980 In other words, we're going to consume that data. 03:53.980 --> 04:01.360 So to do that, we usually make a local float variable that has the value of incoming damage. 04:01.360 --> 04:12.040 So we could make a const float called local incoming damage and set it equal to the result of get incoming 04:12.040 --> 04:12.880 damage. 04:13.060 --> 04:15.460 So we're getting its float value. 04:15.490 --> 04:22.900 So we're caching that value locally and then we can set that meta attribute to zero so we can say set 04:22.900 --> 04:25.750 incoming damage and we can pass in zero. 04:25.750 --> 04:32.080 So now that we have local incoming damage, we can decide what to do with it and we should only really 04:32.080 --> 04:35.230 do anything if its value isn't zero. 04:35.230 --> 04:40.960 So we're going to check if local incoming damage is greater than zero. 04:42.070 --> 04:44.230 And in that case, we can do something. 04:44.230 --> 04:51.700 Now, so far, we have really nothing to do with this meta attribute except to use it to set the health 04:51.700 --> 04:52.450 value. 04:52.480 --> 04:53.710 So we can do that. 04:53.710 --> 04:58.840 We can set the health value and we can even handle any additional clamping as well. 04:58.870 --> 05:07.210 We can make a const float called New Health and calculate what the health should be now and what that 05:07.210 --> 05:13.180 should be is the result of get health minus this local incoming damage. 05:14.450 --> 05:18.920 And we can make sure that that is not going to be a negative value. 05:18.950 --> 05:23.960 So when we call set health, we can call set health with an F math clamp. 05:24.950 --> 05:26.570 Clamping the value. 05:26.600 --> 05:29.210 New health between zero. 05:30.650 --> 05:33.590 And Maxhealth so we can call get Maxhealth. 05:35.090 --> 05:36.470 Now, here's the cool thing. 05:36.470 --> 05:40.620 At this point, we can tell certain things about the damage that has been done. 05:40.640 --> 05:47.660 For example, if new health is now zero, then we know that this damage caused was fatal. 05:47.780 --> 05:54.470 In other words, we could do something like const, bool, be fatal equals new health. 05:56.550 --> 05:58.530 Less than or equal to zero. 05:58.890 --> 06:01.890 Because if new health is less than or equal to zero. 06:01.920 --> 06:04.640 Well, we know that be fatal is going to be true. 06:04.650 --> 06:09.130 If enough damage was done to kill the owner of this attribute set. 06:09.150 --> 06:11.040 So that's kind of neat. 06:11.160 --> 06:16.410 Now we'll be doing more with our meta attribute, but this is the backbone. 06:16.410 --> 06:19.650 This is the basic framework of how it should work. 06:19.680 --> 06:27.060 We use the meta attribute instead of changing health and our gameplay effects that currently affect 06:27.060 --> 06:33.390 health are now going to be changed to affect the meta attribute on the target and they'll be adding 06:33.420 --> 06:33.780 to it. 06:33.780 --> 06:37.500 They won't be subtracting because we do the subtraction here. 06:37.530 --> 06:42.750 Our new health is our health value minus that local incoming damage. 06:42.780 --> 06:48.810 So why don't we change our damage gameplay effect so that it's now using our meta attribute? 06:48.840 --> 06:52.290 We can go ahead and compile and launch the editor. 06:54.460 --> 07:01.330 So back in the editor, we can open up g damage and we can scroll down to its modifier. 07:01.540 --> 07:07.330 And now instead of setting the health attribute, we're going to use incoming damage. 07:07.450 --> 07:12.520 And instead of a negative value, we need this to be a positive value. 07:12.670 --> 07:14.440 I'm going to make it a little larger. 07:14.440 --> 07:19.150 Let's make it 25 and compile and we can do some damage. 07:19.150 --> 07:21.460 I'm going to go ahead and launch a fireball. 07:22.370 --> 07:23.390 And there we go. 07:23.390 --> 07:25.250 We see that it's affecting the health. 07:25.280 --> 07:31.470 We're subtracting 25 from it all because we're adding to that damage meta attribute. 07:31.490 --> 07:39.110 So the damage meta attribute is essentially zeroed out, each frame consumed to be used in calculations 07:39.170 --> 07:41.060 regarding damage. 07:41.180 --> 07:47.790 Now, of course, we can get down to zero life and we haven't programmed anything for death. 07:47.810 --> 07:51.650 We haven't programmed any hit reaction, anything like that. 07:51.650 --> 07:53.380 Those are things that we'll get to. 07:53.390 --> 08:00.660 But now at least we're doing damage with a meta attribute, and that allows us to do lots of things. 08:00.680 --> 08:03.060 We can check the amount of damage done. 08:03.080 --> 08:06.750 We can also perform custom calculations with the damage. 08:06.770 --> 08:08.210 We have options. 08:08.270 --> 08:09.230 All right. 08:09.230 --> 08:11.650 So G damage is looking better. 08:11.660 --> 08:19.520 However, we're still hardcoding 25 for the damage and it would be nice if this damage were somehow 08:19.520 --> 08:22.200 linked to the gameplay ability. 08:22.200 --> 08:28.920 So if the gameplay ability has its own damage variable, how are we going to make sure that our gameplay 08:28.920 --> 08:32.520 effect is using the damage from the gameplay ability? 08:32.550 --> 08:39.390 Well, that's going to bring us to the fourth option for magnitude calculation type, which is set by 08:39.390 --> 08:40.020 caller. 08:40.020 --> 08:42.150 So we'll get into that next. 08:42.180 --> 08:43.290 I'll see you soon.