WEBVTT 00:06.860 --> 00:07.870 Welcome back. 00:07.880 --> 00:15.170 In this video, we're going to take a closer look at clamping and get a bit of a deeper understanding 00:15.170 --> 00:17.210 about how it works in gas. 00:17.240 --> 00:22.790 Now, we've clamped the changes to our health and our mana. 00:22.790 --> 00:32.090 And if we go back to our attributes set to our pre attribute change function, we see that we're getting 00:32.090 --> 00:35.660 the new value and we're clamping the new value. 00:35.660 --> 00:38.530 So where does this new value come from? 00:38.540 --> 00:47.810 Well, it comes from the calculation performed by our modifier in a gameplay effect when a given attribute 00:47.810 --> 00:48.380 changes. 00:48.380 --> 00:55.520 Now, of course, this function is called even when attributes are set directly, but if this is from 00:55.520 --> 01:02.390 a gameplay effect, that modifier returns the result of a calculation and this is receiving that. 01:02.390 --> 01:08.160 And of course we're checking its value, we're clamping it and making sure it doesn't go below zero 01:08.160 --> 01:09.750 or above the max value. 01:09.750 --> 01:10.320 Right? 01:10.860 --> 01:14.220 But let's see how this works with a little bit of testing. 01:14.220 --> 01:20.940 And you may have discovered this problem that we're about to see by Playtesting on your own. 01:22.130 --> 01:23.450 So I'm going to show debug. 01:23.450 --> 01:23.660 Right. 01:23.660 --> 01:27.230 And we have 50 health and our max health is 100. 01:27.290 --> 01:33.650 Now if we step into the fire, we've now made our fire tag five every second. 01:33.680 --> 01:34.190 Okay. 01:34.190 --> 01:35.280 So far so good. 01:35.300 --> 01:38.450 But what if we go and. 01:39.190 --> 01:40.900 Increase our health here. 01:40.900 --> 01:42.640 We'll pick up a health crystal. 01:42.640 --> 01:44.500 It's going up to 61. 01:44.500 --> 01:46.780 And let's pick up another one. 01:46.780 --> 01:47.140 Okay. 01:47.140 --> 01:51.850 It's going up to its 100 and let's pick up another one. 01:51.850 --> 01:58.210 And even though we are clamping our health, we see that our health is not higher than 100. 01:58.420 --> 02:03.340 But I'm going to step into the fire and our health isn't changing. 02:03.340 --> 02:04.720 So what's going on here? 02:04.720 --> 02:06.520 Why is our health not changing? 02:07.330 --> 02:15.490 Well, I'm going to close the editor and come back here and take a look at post gameplay effect execute. 02:15.490 --> 02:23.230 And I'm going to check to see if the attribute that's being changed is our health attribute. 02:23.260 --> 02:29.380 We can check that by saying if and we can take data dot evaluated data. 02:29.380 --> 02:38.770 So we're getting it from our data here dot attribute that gives us a gameplay attribute and we can compare 02:38.770 --> 02:41.920 that with get health attribute. 02:42.430 --> 02:50.350 So if we make it into this if statement, we know that the attribute changed is the health attribute. 02:50.350 --> 02:58.270 So what I'd like to do here is I'd like to see what that value is here in post gameplay effect execute. 02:58.270 --> 03:03.160 So let's go ahead and just print it to the screen. 03:03.160 --> 03:11.270 We're going to say, Gee, engine add on screen debug message and we'll just give it the key of one 03:11.270 --> 03:21.860 time to display three point f seconds f color red and f string print f and we'll format a string that 03:21.860 --> 03:30.230 says health percent f followed by get health. 03:31.580 --> 03:37.400 Okay, so we're going to print a string that says health and the value of our health. 03:37.400 --> 03:39.140 Let's run this in debug mode. 03:39.140 --> 03:45.110 Debug mode is always more useful because we can place breakpoints and check the values of things. 03:45.110 --> 03:48.410 So we're going to run in debug and let's see what happens here. 03:49.410 --> 03:49.800 Okay. 03:49.800 --> 03:56.640 So I'm going to show debug ability system and now I'm noticing that there's red text up here and we 03:56.640 --> 04:00.510 chose red for our color for the debug message. 04:00.510 --> 04:06.060 So we're going to have to try to strain our eyes a little bit to see what it says. 04:06.060 --> 04:13.860 But we see health is 45 and right here health, same value basically is what the bottom line is. 04:13.890 --> 04:16.380 We're getting consistency, right? 04:16.380 --> 04:20.700 But let's see what happens when we do what we did before. 04:20.700 --> 04:28.280 Now, how did we discover that bug where we stopped taking damage from that fire area? 04:28.290 --> 04:30.030 How do we repro that issue? 04:30.030 --> 04:33.060 Well, remember, I picked up a couple health crystals. 04:33.060 --> 04:39.060 I let my health go all the way up to 100, and then I picked up more health crystals. 04:39.060 --> 04:39.660 Okay. 04:39.660 --> 04:42.090 And then I stepped in the fire. 04:43.350 --> 04:43.860 Okay. 04:43.860 --> 04:53.520 So we see in our message and on show debug, we're getting 100 and we're not going down. 04:53.520 --> 05:03.210 So it's the same value here both in post gameplay effect, execute and here in pre attribute change. 05:03.210 --> 05:06.510 So how come we stopped getting damage? 05:06.780 --> 05:12.180 Well, what I'd like to take a look at is the value here of new value before we clamp it. 05:12.360 --> 05:20.190 So I'm going to repro the bug by going and picking up a couple health crystals and then going way up 05:20.190 --> 05:25.080 past 100 or at least trying to and then going and stepping in the fire. 05:25.080 --> 05:30.720 And then I'm going to stick a breakpoint right here and we're going to hit that breakpoint because we're 05:30.720 --> 05:31.650 in the fire. 05:31.890 --> 05:33.900 Now let's hover over new value. 05:33.930 --> 05:40.320 We see that it's 160 and that is not what we expected, right? 05:40.320 --> 05:42.940 Because we should be clamping every time. 05:42.940 --> 05:44.650 So why is it 160? 05:45.140 --> 05:52.520 Well pre attribute change is getting new value from our modifier on the gameplay effect that's being 05:52.520 --> 05:53.360 applied. 05:53.480 --> 05:57.740 And then we're clamping it before the attribute changes. 05:58.280 --> 06:00.340 So that's great. 06:00.350 --> 06:05.770 But this clamp here is not going to permanently change that modifier. 06:05.780 --> 06:12.200 It just changes the value that is being returned from querying that modifier. 06:12.290 --> 06:17.870 And if we have some other gameplay effect that's going to have its own modifier queried, it's going 06:17.870 --> 06:20.720 to recalculate the value from current value. 06:20.720 --> 06:24.170 So it's kind of like the value was never actually clamped. 06:24.200 --> 06:29.600 We clamped it before the attribute changed, but that modifier recalculates. 06:29.600 --> 06:35.480 So if we continue this and then we hit our next breakpoint, we see that it's 155. 06:35.480 --> 06:39.140 So we are going down thanks to that fire area. 06:39.780 --> 06:42.930 But it shouldn't be 155 in the first place, should it? 06:43.140 --> 06:52.020 Now we can properly clamp this by clamping again over here and post game play effect execute because 06:52.020 --> 06:58.230 this happens after the gameplay effect has already been applied, we can clamp that value again and 06:58.230 --> 07:04.470 we don't have to worry that since we're changing it again, maybe it's going to replicate again down 07:04.470 --> 07:05.490 to clients. 07:05.580 --> 07:11.820 No, we can change it here and there will only be a single replication resulting from changing the attributes 07:11.850 --> 07:12.570 value. 07:12.930 --> 07:16.710 So I'm going to remove that breakpoint and continue. 07:17.960 --> 07:23.840 And we'll close out of the editor and here in post gameplay effect execute. 07:23.840 --> 07:36.170 If health is the value being changed, then we're going to say set health equal to F math clamp, get 07:36.200 --> 07:41.930 health, we're going to clamp between zero and get max health. 07:43.670 --> 07:47.930 So let's run and debug mode and see what happens now. 07:48.600 --> 07:54.780 So let's press play and we'll pick up a couple health crystals, go up to 100 health. 07:54.810 --> 07:58.890 We'll pick up another health crystal and go way beyond that. 07:58.890 --> 08:02.340 And we'll go step in the fire and look at that. 08:02.370 --> 08:06.810 We see that our health is going down to the correct values. 08:06.810 --> 08:07.080 Why? 08:07.110 --> 08:13.400 Because we're clamping in post gameplay effect execute and we're actually setting our health. 08:13.410 --> 08:19.110 We're not just changing new value, which is what we were doing up here in pre attribute change. 08:19.110 --> 08:23.370 This just changes the value returned from querying the modifier. 08:23.370 --> 08:28.140 But here in post gameplay effect execute we're actually setting the health. 08:28.140 --> 08:33.120 So this is a legit set of the health attribute. 08:33.330 --> 08:37.110 So yes, we can clamp here in pre attribute change. 08:37.320 --> 08:40.020 That's basically all that this function is good for. 08:40.020 --> 08:47.430 But remember that all this does is clamp what's returned from querying the modifier. 08:47.430 --> 08:54.340 Anything else that queries the modifier again is going to recalculate what's returned from the modifier 08:54.340 --> 08:55.450 of any given effect. 08:55.480 --> 09:03.220 We are going to actually set the value to a clamped value here in post gameplay effect execute. 09:03.220 --> 09:08.440 And when all is said and done, the actual value will be set here. 09:08.560 --> 09:12.370 Okay, so I can go ahead and remove this onscreen debug message. 09:12.370 --> 09:19.210 And now that we understand clamping a little better, let's go ahead and clamp our mana here as well. 09:19.210 --> 09:28.030 So if the attribute is get mana attribute, then we're going to go ahead and clamp it between the value 09:28.030 --> 09:30.880 of get mana and get max Mana. 09:31.810 --> 09:38.650 And of course we're not calling set health, we're calling set mana and now we're clamping mana as well. 09:38.650 --> 09:39.730 So great job. 09:39.730 --> 09:41.380 I'll see you in the next video.