WEBVTT 00:06.830 --> 00:07.910 Welcome back. 00:08.030 --> 00:10.610 Now things are coming along pretty nicely. 00:10.610 --> 00:11.990 We have a nice HUD. 00:12.020 --> 00:14.330 We're showing the abilities that we have. 00:14.330 --> 00:20.480 And now that we have the capability to visualize certain things, it's time to get a little bit deeper 00:20.480 --> 00:26.000 with a couple of important aspects of gameplay abilities, cost and cooldown. 00:26.030 --> 00:33.830 Now, when we launch a fireball, our fireball doesn't actually have a gameplay ability cost. 00:33.830 --> 00:39.980 In other words, in most games you would expect your mana to go down as you spend mana as a resource 00:39.980 --> 00:48.350 to cast a spell so we can implement a cost and a cooldown is also something we're not implementing. 00:48.350 --> 00:55.340 Sure, we can't spam it, but that's only because we're putting a delay in place for our gameplay ability. 00:55.370 --> 01:00.710 Firebolt At the very end, before we end the ability we delay by half a second. 01:00.710 --> 01:02.690 So this is basically a hack. 01:02.690 --> 01:07.080 Without the delay, we could spam this ability as quickly as we want it. 01:07.080 --> 01:10.650 In fact, we could spam it so fast that we could. 01:14.870 --> 01:16.080 Well, do that. 01:16.100 --> 01:21.590 So cooldowns are important and a delay is not a cooldown. 01:21.590 --> 01:26.810 So we're going to implement those in these next couple of videos and we're going to start with a cost. 01:26.810 --> 01:30.770 As a cost is important and we have a mana resource. 01:30.770 --> 01:39.800 So it only makes sense that we spend mana to cast spells so our mana can be affected by a cost and we 01:39.800 --> 01:42.830 implement cost in the gameplay ability itself. 01:42.830 --> 01:49.370 If we click on class defaults and scroll all the way down to the bottom, we have a costs section and 01:49.370 --> 01:53.780 a cooldowns section and notice that both of these have gameplay effects. 01:53.780 --> 01:56.480 That's how cost and Cooldowns are implemented. 01:56.510 --> 01:58.910 They're implemented with gameplay effects. 01:59.090 --> 02:05.990 A cost gameplay effect can be created and assigned right here, and it'll automatically work in a way 02:05.990 --> 02:09.560 that you would expect a gameplay cost to work. 02:09.560 --> 02:13.250 So how do we implement a gameplay cost effect? 02:13.280 --> 02:19.890 Well, we first create the effect and I'm going to create one for our firebolt ability right here in 02:19.890 --> 02:21.660 the Firebolt folder. 02:21.660 --> 02:27.900 I'm going to right click, create a new Blueprint class, search for gameplay effect and choose the 02:27.900 --> 02:35.130 gameplay effect class and call this g underscore cost underscore firebolt. 02:36.290 --> 02:45.380 So we can open the firebolt gameplay effect and all we need to do is leave its duration policy at instant 02:45.380 --> 02:53.180 and add a modifier so we can click plus for the modifiers array, expand it and for the attribute we 02:53.180 --> 03:00.080 choose which attribute is the resource that should be spent to cast this ability. 03:00.170 --> 03:02.980 So in our case we're going to choose Mana. 03:02.990 --> 03:06.770 So we need to find Aura attribute Setmana. 03:06.770 --> 03:14.570 We choose that and we leave the modifier OP at Add and choose a modifier magnitude. 03:14.750 --> 03:21.680 Now we could hardcode a value in here and if we're spending the resource, it has to be negative. 03:21.680 --> 03:25.430 So we're going to put, say, -20 mana. 03:25.790 --> 03:32.210 Now of course you could use a curve table for this and scale it based on the gameplay effects level 03:32.210 --> 03:32.810 as well. 03:32.840 --> 03:40.740 But I'm just going to Hardcode 20 and, and in order to implement this as a cost gameplay effect, all 03:40.740 --> 03:47.130 we do is go over to the Firebolt gameplay ability and set the cost gameplay effect class. 03:47.130 --> 03:51.150 Here we're going to choose GE cost Firebolt. 03:51.240 --> 03:54.360 Now we've assigned a cost gameplay effect. 03:54.510 --> 03:57.930 Now how does this actually get enforced? 03:57.960 --> 04:04.680 Well, there's a function on our gameplay ability that we have to call in order to commit that cost 04:04.680 --> 04:12.260 and we can call that function immediately after activating the ability and it's called commit ability. 04:12.270 --> 04:19.080 Now notice there are several versions we have commit ability, we have commit ability cooldown and commit 04:19.110 --> 04:24.120 ability, cost commit ability will commit both the cooldown and the cost. 04:24.120 --> 04:29.370 And what that means is it will attempt to spend the resources. 04:29.400 --> 04:35.910 In other words, this can fail if we call commit ability and we don't have the proper resources, we 04:35.910 --> 04:39.330 will be prevented from activating the ability. 04:39.330 --> 04:41.670 And this does return a boolean. 04:41.670 --> 04:46.230 And what we can do with this boolean is just print a message. 04:46.260 --> 04:53.490 We're going to print a string and pass that boolean in and see what that boolean value is after calling 04:53.490 --> 04:54.600 commit ability. 04:54.600 --> 04:58.290 So I'm going to compile press play and cast the spell. 04:58.290 --> 04:59.940 Now take a look at our mana. 04:59.940 --> 05:05.790 It has gone down and the server has printed the message true to the screen. 05:05.790 --> 05:06.360 Look at that. 05:06.360 --> 05:06.980 True. 05:06.990 --> 05:15.360 That means that our gay firebolt has reached this commit ability and it has succeeded because there's 05:15.360 --> 05:17.850 enough resources to pay for the spell. 05:17.850 --> 05:19.080 Now we're getting low. 05:19.080 --> 05:21.240 Soon we won't be able to cast it. 05:21.240 --> 05:23.160 It looks like right about here. 05:23.160 --> 05:26.400 Where out of mana or just about out of mana. 05:26.400 --> 05:29.250 It doesn't look like we have enough to pay for the ability. 05:29.250 --> 05:34.290 I'm going to attempt to cast the ability and nothing happens. 05:34.650 --> 05:36.060 Interesting, right? 05:36.060 --> 05:38.820 We don't even get that string printed. 05:38.820 --> 05:43.920 So the return value returns true if the commit ability succeeds. 05:43.920 --> 05:49.350 But if the commit ability does not succeed, it doesn't even reach any farther. 05:49.350 --> 05:51.450 We don't even hit that print string. 05:51.450 --> 05:57.900 Now we can add a print string at the beginning and say ability activated. 05:59.120 --> 06:02.840 And let's see what happens if we spend up all of our mana. 06:03.690 --> 06:06.110 All the way to that last bit of mana. 06:06.120 --> 06:09.270 And now if we attempt to cast. 06:09.300 --> 06:11.850 Look at this, it doesn't even cast. 06:11.850 --> 06:18.780 So even though it's kind of paradoxical, but even though we reach the commit ability, otherwise we 06:18.780 --> 06:23.860 wouldn't be able to check to see if we have any mana if commit ability fails. 06:23.880 --> 06:25.950 This act is undone. 06:25.950 --> 06:30.000 It's as if we never even activated the ability at all. 06:30.330 --> 06:32.690 Kind of crazy right now. 06:32.700 --> 06:36.780 Commit ability, as I said, commits both the cost and the cooldown. 06:36.780 --> 06:43.350 So if we're interested in committing the cost at one point in the ability and the cooldown later on, 06:43.350 --> 06:48.780 we could do that because we have commit ability, cost and commit ability cooldown as well. 06:48.780 --> 06:53.850 But commit ability will do both in one fell swoop if that's what you want. 06:54.710 --> 06:57.020 So I'm going to get rid of those print strings. 06:57.020 --> 06:59.720 And now we're committing an ability cost. 06:59.720 --> 07:03.170 And if we wanted to, we could have that ability. 07:03.170 --> 07:07.340 Cost depend on the level of our ability. 07:07.370 --> 07:13.460 Now game play abilities themselves have a level, and if we use a scalable float, they'll use their 07:13.460 --> 07:14.110 level. 07:14.120 --> 07:20.660 So the question is, is the cost gameplay effect applied at the level of our ability? 07:20.690 --> 07:21.020 Right. 07:21.020 --> 07:26.750 Because we're not applying this gameplay effect, the ability does it automatically with commit ability 07:26.750 --> 07:27.360 cost. 07:27.380 --> 07:35.960 So to answer that question, I'd like to dive into C plus plus and take a look at commit ability cost. 07:35.990 --> 07:44.150 Now here we see it in gameplay ability and I've opened the CPP file and let's see what it does. 07:44.180 --> 07:48.560 It first checks if it should ignore costs which should ignore costs. 07:48.560 --> 07:51.800 And if it does then well, we just succeed. 07:51.800 --> 07:53.600 We don't check the cost. 07:53.630 --> 07:57.630 But then it calls check cost and apply cost. 07:57.660 --> 08:01.320 Now check Cost has a comment that says Last chance to fail. 08:01.350 --> 08:08.190 Maybe we no longer have resources to commit since after we started this ability activation and then 08:08.190 --> 08:09.330 we have apply cost. 08:09.360 --> 08:12.210 Now I'd like to take a look at apply cost. 08:12.570 --> 08:19.800 Here we see apply gameplay effect to owner and here's where we can see what level we're passing in for 08:19.800 --> 08:20.760 the gameplay effect. 08:20.760 --> 08:21.720 And take a look. 08:21.750 --> 08:28.290 We're passing in get ability level, so sure enough that gameplay effect will be applied at the level 08:28.290 --> 08:30.050 of our current ability. 08:30.060 --> 08:39.030 So if we want to, we can have a scalable float, we can have a curve table that will scale our cost 08:39.030 --> 08:41.280 depending on the ability level. 08:41.760 --> 08:42.870 Kind of cool. 08:43.110 --> 08:45.570 And that's going to be your quest. 08:45.600 --> 08:52.050 I'd like you to create a curve table for gameplay ability costs so you can create this curve table. 08:52.050 --> 08:58.530 You can call it cost curve table if you like, and add a cost curve for the firebolt ability and make 08:58.530 --> 09:04.170 sure you scale that manacost based on the level as you see fit. 09:04.200 --> 09:07.680 Pause the video and make this curve table now. 09:10.670 --> 09:18.470 Okay, so I'm going to make a curved table and I'm going to stick it in ability system data. 09:18.590 --> 09:28.460 And this means I need to go to miscellaneous Choose Curve table and this can be a constant curve table. 09:28.670 --> 09:32.930 I'm going to call this city underscore cost. 09:32.960 --> 09:34.390 We could call it ability cost. 09:34.400 --> 09:36.560 I'm just going to call it cost. 09:37.100 --> 09:38.350 Open that up. 09:38.360 --> 09:39.530 We have a curve. 09:39.530 --> 09:44.300 I'm going to rename it to Fire Dot Fire Bolt. 09:44.930 --> 09:55.520 And selecting it, I can click to add my level one value and I'm going to use positive numbers here. 09:55.880 --> 09:58.970 My first manacost will be 20. 09:59.000 --> 10:01.760 I'm going to keep it at 20. 10:01.790 --> 10:05.510 Actually, we'll go up to 25 at level two. 10:05.810 --> 10:09.140 35 at level three. 10:10.170 --> 10:19.440 Let's do 50 at level four, 91, 2150. 10:19.890 --> 10:21.300 We'll do two more. 10:22.100 --> 10:24.980 180 and 200. 10:26.550 --> 10:28.800 And we can take a look at the curve. 10:28.830 --> 10:32.190 And here's what it looks like, a nice step curve. 10:32.520 --> 10:39.810 So now that we have that, we can go back to cost firebolt and for the scalable float, we can use the 10:39.810 --> 10:48.300 curve table CT cost and instead of -20, we are going to use the scale value of negative one as our 10:48.330 --> 10:51.090 CT cost values are all positive, right? 10:51.090 --> 10:59.040 And for the curve, we're going to choose fire firebolt and we can see what that cost is at the levels 10:59.040 --> 11:00.660 zero through ten. 11:02.520 --> 11:03.300 Okay. 11:03.330 --> 11:07.920 Now our ability is given at level one, isn't it? 11:07.950 --> 11:14.040 So really, if we want that ability given at a higher level, let's go and look at where we're giving 11:14.040 --> 11:15.090 that ability. 11:15.180 --> 11:21.090 Here in the ability system component, when we create the ability spec, we're creating it at level 11:21.090 --> 11:21.900 one. 11:21.900 --> 11:28.800 So if we change this to two now, we can take a look at how that affects our cost. 11:28.830 --> 11:31.770 It should go from 20 to 25. 11:33.600 --> 11:35.250 So I'm going to close the editor. 11:36.290 --> 11:37.250 And you know what? 11:37.250 --> 11:40.760 Just to see a more dramatic change, let's put it at a higher level. 11:40.760 --> 11:45.500 Let's do five and we'll go ahead and compile and launch. 11:46.250 --> 11:51.410 And hopefully I have enough mana to pay for this cost at level five. 11:51.440 --> 11:53.240 That's going to be 70 mana. 11:53.270 --> 11:55.910 Let's see if it goes down more. 11:56.390 --> 11:59.070 Sure enough, it goes down a lot more. 11:59.090 --> 12:06.890 So our cost is scaled by the level according to our firebolt step curve. 12:06.980 --> 12:08.990 So that's looking great. 12:08.990 --> 12:12.200 I'm going to go ahead and close out of these. 12:13.090 --> 12:16.270 Tabs will open things again if we need to. 12:16.270 --> 12:18.130 And we have a cost. 12:18.160 --> 12:18.820 Excellent. 12:18.820 --> 12:19.570 Excellent job. 12:19.570 --> 12:24.430 I'm going to change this back so that we're applying the ability spec at level one. 12:24.670 --> 12:29.290 Go ahead and compile that great job and I'll see you in the next video.