1 00:00:04,340 --> 00:00:05,390 ‫Hello and welcome. 2 00:00:05,390 --> 00:00:09,320 ‫In this lecture, we're going to be dealing damage to this actor here. 3 00:00:09,320 --> 00:00:13,610 ‫We're going to do that by overriding a virtual method called take damage on the actor. 4 00:00:13,610 --> 00:00:18,380 ‫And you can see in the log here, we've got the health decreasing as I shoot this character all the 5 00:00:18,380 --> 00:00:21,860 ‫way down to zero and then it stops at zero, not going into negative numbers. 6 00:00:21,860 --> 00:00:23,780 ‫So let's dive in and see how that's done. 7 00:00:26,450 --> 00:00:33,050 ‫So while we are currently being able to do damage to the actors that we hit here, such as this guy, 8 00:00:33,380 --> 00:00:36,590 ‫we are not actually receiving that damage. 9 00:00:36,590 --> 00:00:43,190 ‫So this is where virtual methods of last lecture come in because just like begin, play or tic, we 10 00:00:43,190 --> 00:00:46,080 ‫want to be able to receive damage on an actor. 11 00:00:46,100 --> 00:00:50,690 ‫Now, fortunately, if you go to the actor H and have a little look in here, you can see that there 12 00:00:50,690 --> 00:00:53,160 ‫is this take damage virtual method. 13 00:00:53,180 --> 00:01:00,410 ‫Now this can be done also with events and you will possibly have seen it done that way before where 14 00:01:00,410 --> 00:01:01,470 ‫you register for events. 15 00:01:01,490 --> 00:01:06,980 ‫Now what I'm going to do is just a different way of doing damage, where we actually have damage stored 16 00:01:06,980 --> 00:01:09,680 ‫against the actor rather than in a component. 17 00:01:10,160 --> 00:01:15,950 ‫And one easy way of receiving that damage is through a virtual method here. 18 00:01:15,950 --> 00:01:18,620 ‫And this is the virtual method that we're going to override. 19 00:01:18,620 --> 00:01:25,210 ‫So I'm going to go ahead and copy this and go over to our particular actor, which is the shooter character 20 00:01:25,250 --> 00:01:31,340 ‫is going to be quicker to go and search for the shooter character dot H And the one thing that I wanted 21 00:01:31,340 --> 00:01:35,480 ‫to check is where this comes in, the actor dot H. 22 00:01:35,720 --> 00:01:41,660 ‫So if we scroll up, we should be able to see which section we are in here. 23 00:01:42,080 --> 00:01:50,090 ‫So I'm just going to scroll right up until I find that what whether we're in public or what they go, 24 00:01:50,090 --> 00:01:51,200 ‫we're in the public section. 25 00:01:51,200 --> 00:01:54,530 ‫So this ought to be in the public section here as well. 26 00:01:54,530 --> 00:02:00,200 ‫So I'm just going to stick it underneath our tick and set up player input component over in the shooter 27 00:02:00,440 --> 00:02:09,650 ‫H and we just paste it in and as I said in the last lecture, you can use override to make sure that 28 00:02:09,650 --> 00:02:14,690 ‫you're indeed overriding a virtual method from the parent and it's not necessary to have virtual in 29 00:02:14,690 --> 00:02:17,180 ‫front here, but we'll keep it anyway. 30 00:02:17,180 --> 00:02:21,560 ‫And here you can see all of the data that's coming in to take damage. 31 00:02:21,560 --> 00:02:29,690 ‫We have got a damage amount, the damage event and the controller that is causing the damage, the instigator 32 00:02:29,690 --> 00:02:30,530 ‫and the damage cause. 33 00:02:30,530 --> 00:02:34,250 ‫All that stuff that we'd passed in from the gun is cropping up here as well. 34 00:02:34,250 --> 00:02:35,150 ‫So that's great. 35 00:02:35,150 --> 00:02:41,300 ‫Now if we go ahead and do a control shift P create implementation or copy and paste, then we can go 36 00:02:41,300 --> 00:02:43,820 ‫and make the implementation for take damage. 37 00:02:43,820 --> 00:02:49,250 ‫But the first thing to be wary of is that whenever we're overriding something, we want to think about 38 00:02:49,250 --> 00:02:56,660 ‫calling the the parent class version of take damage because there may be some implementation in there 39 00:02:56,660 --> 00:02:58,580 ‫that needs to run. 40 00:02:58,940 --> 00:03:00,140 ‫So that's what we're going to do. 41 00:03:00,170 --> 00:03:01,070 ‫We do this always. 42 00:03:01,070 --> 00:03:02,210 ‫We've done it with tech. 43 00:03:02,210 --> 00:03:03,710 ‫We've done it with Begin Play. 44 00:03:03,710 --> 00:03:07,580 ‫You can see we've always got this super cool at the beginning, and that's because when we override 45 00:03:07,580 --> 00:03:09,200 ‫a method, we override it completely. 46 00:03:09,200 --> 00:03:11,120 ‫We completely remove that behavior. 47 00:03:11,120 --> 00:03:17,000 ‫So if we do want that behavior, which we typically do, then we should always start with a cool to 48 00:03:17,000 --> 00:03:17,630 ‫super. 49 00:03:17,630 --> 00:03:20,000 ‫So we're going to do a cool take damage. 50 00:03:21,450 --> 00:03:23,580 ‫That's going to take the damage amount. 51 00:03:23,580 --> 00:03:25,760 ‫So this is where it gets a little bit tedious, sadly. 52 00:03:25,800 --> 00:03:27,870 ‫My autocomplete tool doesn't do this for us. 53 00:03:27,870 --> 00:03:29,250 ‫Damage event. 54 00:03:30,560 --> 00:03:32,660 ‫Then what was the next one? 55 00:03:32,660 --> 00:03:34,970 ‫We had the control. 56 00:03:35,180 --> 00:03:37,550 ‫So the event instigator, let's just copy. 57 00:03:37,820 --> 00:03:42,380 ‫And then we've got the damage causer, which is the actor. 58 00:03:43,160 --> 00:03:48,320 ‫So all of that gets called up to the parent implementation of take damage. 59 00:03:48,560 --> 00:03:52,220 ‫And the one other thing is that this has a return type. 60 00:03:52,220 --> 00:03:55,880 ‫So the actual damage applied so we're going to do float. 61 00:03:56,750 --> 00:04:01,460 ‫Damage applied is the return value from take damage. 62 00:04:01,460 --> 00:04:05,000 ‫So we're just going to keep hold of that damage applied there. 63 00:04:05,270 --> 00:04:11,450 ‫And realistically, that's going to be the same as the damage amount in our particular use case, but 64 00:04:11,450 --> 00:04:14,690 ‫not necessarily so we're going to use the damage applied. 65 00:04:14,720 --> 00:04:21,000 ‫The next thing we want to do is keep hold of the information about how much health we've actually got. 66 00:04:21,020 --> 00:04:24,980 ‫Now the way I'm going to do this is with two variables here. 67 00:04:25,010 --> 00:04:30,260 ‫The first one is I'm going to make both of them new properties because I want to make the health visible 68 00:04:30,260 --> 00:04:32,090 ‫in the inspector, at least for now. 69 00:04:32,420 --> 00:04:37,220 ‫And we're going to have the first property be the max health. 70 00:04:37,220 --> 00:04:39,620 ‫That's what we initialize the health to initially. 71 00:04:39,620 --> 00:04:48,170 ‫So you property, it's going to be an edit default only because it's going to be used in begin play. 72 00:04:48,170 --> 00:04:53,120 ‫And so changing that value of max health after the effect, it's not going to have any impact. 73 00:04:53,120 --> 00:05:01,340 ‫So Max health, I'm going to set the max health to 100 here and then we're going to have one other property 74 00:05:01,340 --> 00:05:06,230 ‫here, which, as I've said, is going to be a new property just for us to be able to inspect it. 75 00:05:06,230 --> 00:05:09,770 ‫And I'm going to have that as visible anywhere. 76 00:05:10,690 --> 00:05:15,310 ‫But not editable because we don't want to be able to change that health, at least not at the moment. 77 00:05:15,520 --> 00:05:18,950 ‫You might want that for debugging purposes, but I don't. 78 00:05:18,970 --> 00:05:23,080 ‫So we're going to have health here and in play. 79 00:05:23,260 --> 00:05:27,250 ‫We're going to set it up so that that health. 80 00:05:28,080 --> 00:05:31,060 ‫Is equal to the max health. 81 00:05:31,080 --> 00:05:32,460 ‫So we start off with spawn. 82 00:05:32,460 --> 00:05:36,150 ‫We have our maximum health and then we can start decreasing it. 83 00:05:36,780 --> 00:05:41,760 ‫So it's time for a challenge for you to decrease the health of the character. 84 00:05:41,760 --> 00:05:48,480 ‫So you're going to use the damage applied here rather than the other option here. 85 00:05:48,480 --> 00:05:52,710 ‫So we've got our shooter character, CP take damage. 86 00:05:52,710 --> 00:05:57,450 ‫We've got a damage amount, but we actually want the damage applied that comes back from take damage 87 00:05:57,450 --> 00:06:02,100 ‫because that could have been reduced by some process in the parent. 88 00:06:02,550 --> 00:06:03,420 ‫So we do that. 89 00:06:03,420 --> 00:06:10,410 ‫Then we reduce the value of health and log the results just for simplicity's sake so that you can check 90 00:06:10,410 --> 00:06:16,050 ‫that when you're shooting at that eye that his health is going down and then test it out. 91 00:06:16,050 --> 00:06:17,820 ‫So pause the video and have a go. 92 00:06:18,060 --> 00:06:19,200 ‫Okay, welcome back. 93 00:06:19,200 --> 00:06:20,550 ‫So let's give it a shot. 94 00:06:20,550 --> 00:06:27,930 ‫So health, we basically want to decrease that by the damage applied. 95 00:06:29,260 --> 00:06:30,820 ‫But is that enough? 96 00:06:30,850 --> 00:06:37,150 ‫Well, what if our damage applied is greater than the amount of health we have got left? 97 00:06:37,330 --> 00:06:43,830 ‫Well, in that case, we probably want the damage applied to be that amount of health. 98 00:06:43,840 --> 00:06:47,860 ‫So the way we can do this is we can say that the damage applied. 99 00:06:48,770 --> 00:06:54,620 ‫Should be equal to the f math dot min of the health. 100 00:06:55,610 --> 00:06:57,870 ‫And the damage applied. 101 00:06:57,890 --> 00:07:01,010 ‫So this is the damage that we basically want to apply. 102 00:07:01,130 --> 00:07:06,260 ‫So we're going to I'm actually going to go ahead and rename that instead of calling it damage applied. 103 00:07:06,380 --> 00:07:10,040 ‫I'm going to call it the damage to apply. 104 00:07:10,780 --> 00:07:13,480 ‫Damage to apply. 105 00:07:13,900 --> 00:07:18,490 ‫So go rename that throughout here and then the damage to apply. 106 00:07:18,520 --> 00:07:21,450 ‫We're going to health minus the damage to apply. 107 00:07:21,460 --> 00:07:22,180 ‫That makes sense. 108 00:07:22,180 --> 00:07:25,270 ‫And the basically at worst that's going to be the health. 109 00:07:25,270 --> 00:07:28,270 ‫So that's going to set our health down to zero. 110 00:07:28,840 --> 00:07:33,070 ‫And remember, we're supposed to return the damage that we actually applied. 111 00:07:33,070 --> 00:07:41,530 ‫So we'll do a return damage to apply, which has now been applied and we finally want a UII log at the 112 00:07:41,530 --> 00:07:45,430 ‫end here, which is just going to be a warning so we can see it. 113 00:07:46,150 --> 00:07:54,310 ‫And I want this to be the health left here and it's going to be a percent F to or percent lowercase 114 00:07:54,310 --> 00:07:56,020 ‫F to show a float. 115 00:07:56,230 --> 00:08:03,070 ‫And then we can pop in the health right there and go ahead and hit build. 116 00:08:04,890 --> 00:08:05,220 ‫Now. 117 00:08:05,250 --> 00:08:08,460 ‫Mine's compiled after fixing a missing semicolon. 118 00:08:08,460 --> 00:08:15,840 ‫Here, let's go and make sure that we have a window developer tools and we want the output log here 119 00:08:15,840 --> 00:08:18,060 ‫so that we can see that log message. 120 00:08:18,060 --> 00:08:25,710 ‫And I'm going to go ahead and hit play and go and try and shoot at this character if I shoot him. 121 00:08:25,710 --> 00:08:26,170 ‫There you go. 122 00:08:26,190 --> 00:08:30,210 ‫Health left 1976, blah, blah, blah, all the way down to zero. 123 00:08:30,210 --> 00:08:35,490 ‫And if I keep shooting, we don't go below zero because of that eff math dot min. 124 00:08:35,490 --> 00:08:38,370 ‫So that tells me that we've got our health set up correctly. 125 00:08:38,370 --> 00:08:42,180 ‫Just another way of doing it as opposed to doing it within a component. 126 00:08:42,180 --> 00:08:46,680 ‫You can do it within the actor as well as some pros and cons of that approach. 127 00:08:46,710 --> 00:08:51,780 ‫Eventually, you may want to strip this out into a separate component so that you can reuse it on different 128 00:08:51,780 --> 00:08:52,410 ‫elements. 129 00:08:52,410 --> 00:08:57,990 ‫But this is just another way, as I say now, because this character isn't looking particularly dead 130 00:08:57,990 --> 00:09:00,120 ‫after we've shot him down to zero health. 131 00:09:00,120 --> 00:09:02,910 ‫We need to fix up the animations to support that. 132 00:09:02,910 --> 00:09:06,180 ‫So we'll see that in the next lecture and I'll see you there.