WEBVTT 00:06.910 --> 00:08.170 Welcome back. 00:08.410 --> 00:11.110 Now let's take a look at one of our gameplay effects. 00:11.110 --> 00:15.760 I have Crystal Manor open here and I'm going to scroll down. 00:15.760 --> 00:22.990 And because this gameplay effect has duration, we have the ability to configure its stacking options. 00:23.080 --> 00:31.420 Notice we have a stacking section and we have a stacking type and stacking type can be set to none or 00:31.420 --> 00:35.260 aggregate by source or aggregate by target. 00:35.290 --> 00:37.210 Now it's set to none. 00:37.210 --> 00:43.220 And I want to see what happens when we pick up two of these or maybe 3 or 4. 00:43.240 --> 00:51.850 So I'm going to take this man a crystal and duplicate it a few times and I'll have these sort of all 00:51.850 --> 00:55.420 next to each other so we can pick them all up very rapidly. 00:55.570 --> 00:59.620 And let's see what happens with none as the stacking type. 00:59.620 --> 01:02.320 I'm going to pick all three up and look at that. 01:02.320 --> 01:08.680 Our mana goes up and in fact, let's look at the numerical value using show debug. 01:08.690 --> 01:14.120 Our mana is set to ten and if I pick up all three of them, look at that. 01:14.120 --> 01:16.450 It's going up really rapidly. 01:16.460 --> 01:19.310 Now that seems like stacking, doesn't it? 01:19.310 --> 01:23.030 But that's not what stacking really is. 01:23.060 --> 01:27.590 Without any stacking, we just apply the effect three times. 01:27.590 --> 01:34.700 Each one has its own duration and they're all sort of being applied at the same time and we end up getting 01:34.700 --> 01:40.670 three times as much mana as if we were to pick up just a single crystal, right. 01:40.850 --> 01:43.820 So that's the behavior without stacking. 01:44.000 --> 01:47.270 So what behavior do we get with stacking? 01:47.270 --> 01:53.720 Well, if we do have stacking and we choose one of these options, we can choose exactly what type of 01:53.720 --> 01:55.190 behavior we see. 01:55.220 --> 02:01.930 For example, let's say we wanted to pick up one crystal and that crystal has a duration of two seconds. 02:01.940 --> 02:05.960 Well, what if during that two seconds we pick up another crystal? 02:05.990 --> 02:08.160 What behavior would we want to see? 02:08.180 --> 02:11.900 We don't want our mana increasing twice as fast. 02:11.930 --> 02:18.430 Maybe we want to still just increase mana at the same rate, but we want to refresh that duration. 02:18.440 --> 02:24.200 So say we pick up the first crystal and one second in, we pick up the second crystal. 02:24.230 --> 02:30.710 Maybe we just want the duration refreshed so we get our mana increased for another two seconds. 02:30.740 --> 02:37.160 It's things like that that are stacking parameters allow us to configure. 02:37.250 --> 02:44.510 So the first two things we should talk about are these options for the stacking type aggregate by source 02:44.510 --> 02:46.340 and aggregate by target. 02:46.430 --> 02:48.050 How do these work? 02:48.540 --> 02:54.060 So the first stacking type option, aside from none is aggregate by source. 02:54.240 --> 02:55.950 Let's see how this works. 02:55.980 --> 02:59.970 Let's say we set our stack limit count to two. 03:00.300 --> 03:08.370 Well, aggregate by source means that that stack limit count is enforced per source. 03:08.670 --> 03:16.980 So if we have one source and it applies a gameplay effect to the target, we count that as one stack 03:17.010 --> 03:21.990 of the gameplay effect and it's aggregated on the source. 03:21.990 --> 03:28.380 So the source now has one stack count for this gameplay effect applied to the target. 03:28.500 --> 03:33.450 Now the same source applies that same gameplay effect again, right? 03:33.450 --> 03:39.240 And we count this as the second stack and that's aggregated by the source. 03:39.450 --> 03:45.240 Now at this point we have two stacks of the gameplay effect and that's the limit. 03:45.270 --> 03:48.430 We set our stack limit count for this effect to two. 03:48.460 --> 03:56.050 So if the same source applies the same effect, again this would be the third stack, but that exceeds 03:56.050 --> 03:56.740 the limit. 03:56.740 --> 03:59.560 So this effect can't be applied. 03:59.650 --> 04:07.630 Now we're aggregating by source, which means each source keeps a count of the stacks of this particular 04:07.630 --> 04:09.870 effect caused by the source. 04:09.880 --> 04:15.730 So say we get another source in the game that applies this same gameplay effect. 04:15.760 --> 04:18.910 Well, we're aggregating our stacks by source. 04:18.910 --> 04:22.630 So for this source, this is only the first stack. 04:22.630 --> 04:27.370 And so we aggregate that stack by that specific source. 04:27.370 --> 04:34.900 So now the target has two stacks of this effect applied from the first source and one stack applied 04:34.900 --> 04:36.010 from the third. 04:36.580 --> 04:43.780 Now that may seem to exceed the stack limit count, but we're aggregating by source so we can have a 04:43.780 --> 04:48.070 maximum of two stacks per source applied to the target. 04:48.430 --> 04:56.860 Now let's compare this to the other option aggregate by target before we were aggregating by source. 04:56.890 --> 04:59.200 Now we're aggregating by Target. 04:59.200 --> 05:00.640 So say we have a source. 05:00.640 --> 05:02.470 It applies the gameplay effect. 05:02.500 --> 05:10.240 This counts as a single stack and this stack is aggregated by the target this time instead of the source. 05:10.480 --> 05:13.150 Now that same source applies the effect. 05:13.150 --> 05:19.750 Again, this counts as the second stack, and that's added to the stack count which is aggregated by 05:19.750 --> 05:20.740 the target. 05:20.770 --> 05:25.240 Now the same source can attempt to apply another stack. 05:25.270 --> 05:30.460 That would be the third one, but of course that exceeds the stack limit count, right? 05:30.460 --> 05:34.330 So as we'd expect, that stack cannot be applied. 05:34.330 --> 05:40.090 But along comes another source attempting to apply this effect. 05:40.090 --> 05:46.690 And if we were aggregating by source, this source hasn't applied any stacks yet, but we're aggregating 05:46.690 --> 05:50.350 by Target and the target already has two stacks applied. 05:50.350 --> 05:57.250 So for this new source attempting to apply this effect, this would be the third stack on the target 05:57.250 --> 05:59.650 and the stack limit count is two. 05:59.650 --> 06:00.850 This would exceed that. 06:00.850 --> 06:04.180 So this effect cannot be applied. 06:04.540 --> 06:09.400 So that's the difference between aggregating by source and by target. 06:09.400 --> 06:16.690 By source means there's a limit per source, but by target means there's a limit per target. 06:17.050 --> 06:23.470 So in our case, let's say we choose aggregate by source and we set a stack limit count of two. 06:23.980 --> 06:30.310 Now the duration I'd like to set to one second to make our math simple here. 06:30.310 --> 06:38.370 And the period is going to be 0.1 and I'm going to uncheck execute periodic effect on application. 06:38.380 --> 06:45.640 Now, this means that for one second we'll execute our modifiers ten times, and because we're adding 06:45.640 --> 06:53.230 one to our mana, we should see a total of ten added to our mana over the space of a second per mana 06:53.230 --> 06:53.800 crystal. 06:53.830 --> 06:54.550 Right. 06:54.580 --> 06:55.810 That makes sense. 06:55.810 --> 06:59.530 So let's duplicate one of the crystals and move it over here. 06:59.530 --> 07:07.510 Press play show debug ability system and we see that our mana is ten and if I pick up a single health 07:07.510 --> 07:12.040 crystal I should see it go up to 20 within the space of a second. 07:12.070 --> 07:13.240 Makes sense. 07:13.870 --> 07:22.060 Okay, now we set our stacking type to aggregate by source with a stack limit count of two. 07:22.090 --> 07:23.860 Well, what do we mean by source? 07:23.860 --> 07:29.440 Source is referring to actually an ability system component that's causing this. 07:29.440 --> 07:33.400 So we're causing this effect by actors. 07:33.670 --> 07:39.250 So in our case, it doesn't matter if we choose source or target, we're going to get a stack limit 07:39.280 --> 07:40.750 of two and forced. 07:40.750 --> 07:46.570 So we should only see our mana go up by 20 total. 07:46.570 --> 07:47.800 So we have ten. 07:47.980 --> 07:53.320 If we pick up all three, we go up to 30, which is 20 more than we had before. 07:53.530 --> 08:00.280 So once we start having ability system components as the source, we should start being able to test 08:00.280 --> 08:01.330 that out. 08:01.360 --> 08:07.990 Now we have a stack duration refresh policy and it says policy for how the effect duration should be 08:07.990 --> 08:13.540 refreshed while stacking and it's set to refresh on successful application. 08:13.540 --> 08:21.580 If we choose never refresh, then even though we're adding stacks, that duration of one second is what 08:21.580 --> 08:22.240 prevails. 08:22.240 --> 08:30.580 So if we set this to never refresh and we go on to pick up some mana crystals, I'm going to show debug. 08:30.580 --> 08:35.920 We have a mana of ten, I'm going to pick one up and then pick up another notice. 08:35.920 --> 08:43.630 We didn't get all the way up to 30 because that full second had elapsed before we reached 30. 08:43.930 --> 08:48.060 So it doesn't matter how many stacks we have. 08:48.060 --> 08:52.470 This effect will expire at the end of a second, no matter what. 08:53.130 --> 09:01.320 But with refresh on successful application, each time we stack another one on it resets the duration 09:01.320 --> 09:03.270 and you get an additional second. 09:03.450 --> 09:10.560 Now we have a stack period reset policy and this is similar to the duration refresh policy only. 09:10.560 --> 09:13.200 It's for the period itself. 09:13.200 --> 09:21.870 So if you're waiting for the next periodic change to an attribute, when we stack a new stack of this 09:21.870 --> 09:29.790 effect, reset on successful application means reset that period and start waiting for another full 09:29.790 --> 09:30.690 period. 09:30.870 --> 09:38.300 Otherwise, never reset means well, we won't reset that period and expiration policy is set to clear 09:38.310 --> 09:45.690 entire stack, which means as soon as this effect expires, all of the stacks are cleared. 09:45.690 --> 09:53.380 But you can choose to set this to remove single stack and refresh duration, which means that as the 09:53.380 --> 10:00.130 duration finishes, we remove a single stack and then the duration starts over again. 10:00.370 --> 10:06.760 So you can have two of these effects stacked on and when the duration expires, the stack count goes 10:06.760 --> 10:11.680 down to one and then the duration count starts over again. 10:11.830 --> 10:16.510 So as you can see, we have a lot of options when it comes to stacking. 10:16.510 --> 10:20.890 And it really just depends on how you want these things to stack in your game. 10:20.890 --> 10:26.590 And throughout the project, we'll be creating lots of effects and choosing how they can stack. 10:26.710 --> 10:33.310 For now, for the Manna Crystal, I'd like to leave it at aggregate by Target with a stack limit count 10:33.310 --> 10:34.460 of two. 10:34.480 --> 10:39.220 I'd like to refresh the duration on successful application. 10:39.250 --> 10:46.120 I'd like to reset the period on successful application and as soon as a stack expires, I'd like to 10:46.120 --> 10:51.130 clear the whole stack and the duration can be left at one. 10:51.130 --> 10:53.170 And the stack expiration policy. 10:53.170 --> 10:57.130 I'm going to set to remove single stack and refresh duration. 10:57.280 --> 11:04.570 That way, as we pick up more and more crystals, then we extend the duration and we can potentially 11:04.570 --> 11:05.670 gain more mana. 11:05.680 --> 11:12.010 So if I spread these out, we can kind of see the result of this combination of parameters. 11:12.010 --> 11:13.600 So I'm going to press play. 11:14.650 --> 11:17.430 I'm going to show debug and I have ten mana. 11:17.440 --> 11:20.860 If I pick up one, I just get ten more mana. 11:20.860 --> 11:24.340 If I pick up another one and then another one. 11:25.280 --> 11:32.660 I got 20 more, and that's because I refreshed that duration when I got a new stack. 11:32.660 --> 11:37.280 But if I start off with ten and I pick up all four of these. 11:39.840 --> 11:46.230 Notice that I only go up to 56 and that's because I'm picking them up one after the other and each time 11:46.230 --> 11:49.170 I pick it up, I reset that duration. 11:49.350 --> 11:57.330 And notice that no matter how many stacks I have, I'm always just gaining one mana every 10th of a 11:57.330 --> 11:58.230 second. 11:58.260 --> 12:04.680 Whereas if we didn't stack at all, if I set this back to none, then picking up a whole bunch of these 12:04.680 --> 12:13.350 results in a very fast increase in mana and setting it back to say, aggregate by target with a stack 12:13.350 --> 12:21.510 limit count of one, for example, then we can continue prolonging the stack duration but always get 12:21.510 --> 12:24.210 the same rate of increase of mana. 12:24.210 --> 12:30.960 So let's pick up all of these and we'll see that we increase that duration, but we're only ever getting 12:30.960 --> 12:32.010 one mana. 12:33.080 --> 12:37.160 Ten times a second because we're limiting to one stack. 12:37.550 --> 12:44.390 So picking up a crystal before the previous stack expired simply resets the duration. 12:46.910 --> 12:53.690 So I know it's kind of a lot to take in, but we have a lot of options here and we'll see how they can 12:53.690 --> 12:56.990 be combined and set up throughout the course. 12:57.320 --> 13:04.460 Now, the last of the stack expiration policy is refreshed duration, which means that when this stack 13:04.460 --> 13:10.160 expires, refresh the duration, even if it's the one and only stack. 13:10.190 --> 13:15.820 This essentially makes the effect infinite in duration because it keeps refreshing. 13:15.860 --> 13:23.270 So the comment says this can be used to manually handle stack decrements via on stack count change callback. 13:23.860 --> 13:28.030 So there's ways to respond to when the stack count changes and we'll get to that. 13:28.030 --> 13:34.030 But if I set this to refresh duration, watch what happens if I pick up just a single crystal. 13:34.660 --> 13:41.860 We see that it keeps going and it never stops because each time the stack expires, we refresh the duration. 13:41.860 --> 13:46.930 So that's a way to get a sort of infinite duration, periodic effect. 13:47.290 --> 13:51.700 I'm going to go ahead and leave this at clear entire stack. 13:51.880 --> 14:00.220 That way as we can pick up multiple ones, we'll clear the stack completely as soon as that duration 14:00.220 --> 14:01.210 runs out. 14:01.390 --> 14:07.750 And before we wrap up, why don't we just go to the Crystal Heal gameplay effect and set its stacking 14:07.780 --> 14:08.290 type? 14:08.290 --> 14:14.410 I'm going to set it to aggregate by target, set a stack limit count of one and just like Crystal Manna, 14:14.410 --> 14:20.650 we'll leave it at refresh on successful application and reset on successful application. 14:20.650 --> 14:26.360 And just like Crystal Manna, we'll leave it at clear entire stack as well. 14:26.510 --> 14:31.670 And that way we've got a little bit of throttling if we pick up too many at the same time. 14:31.670 --> 14:36.740 So great job we now know about stacking and I'll see you in the next video.