WEBVTT 00:06.810 --> 00:07.960 Welcome back. 00:07.980 --> 00:15.270 In this section, we're concerned with implementing the cornerstone of all RPGs experience and leveling 00:15.270 --> 00:15.740 up. 00:15.750 --> 00:22.170 Now, if you're creating an RPG, then you've likely played many of them and you're well aware of how 00:22.170 --> 00:24.540 experience and leveling up works. 00:24.540 --> 00:28.110 But let's just make sure we're on the same page about all this. 00:28.260 --> 00:32.940 In RPG games that have experience, the player has a level. 00:32.970 --> 00:39.930 Usually you begin at level one, but not always, and you start off with an amount of experience also 00:39.930 --> 00:41.370 referred to as XP. 00:42.090 --> 00:49.710 Usually your XP begins empty and you can typically see it on the screen in the HUD in the form of an 00:49.740 --> 00:50.820 XP bar. 00:50.820 --> 00:55.380 Now when you do things in the game that are significant, you're awarded XP. 00:55.410 --> 01:02.460 So you start to see your XP bar steadily increasing until it gets almost filled up, at which point 01:02.460 --> 01:09.400 the next time you gain XP is going to push your bar up to full and perhaps beyond. 01:09.400 --> 01:12.070 At this point it's said that you level up. 01:12.130 --> 01:20.350 This is associated with an award, usually in the form of your level going up and your XP bar draining 01:20.350 --> 01:26.350 back down to empty, at which point you're going to repeat the process, continue doing significant 01:26.350 --> 01:33.430 things in the game, Gaining XP and leveling up yet again in each level up is generally associated with 01:33.430 --> 01:41.650 an increase in power capability and in general the player's capacity to affect the game world in more 01:41.650 --> 01:42.970 dramatic ways. 01:43.030 --> 01:48.520 This is essential to the RPG game loop and keeping players engaged. 01:48.550 --> 01:52.600 Now let's talk about how a system like this works mathematically. 01:52.630 --> 01:59.980 Let's say that we're starting off at level one, which means that we have an XP bar and our experience 01:59.980 --> 02:02.470 points begin empty with zero. 02:02.470 --> 02:10.030 And let's just say that in order to level up to level two, we have to reach 300 experience points. 02:10.030 --> 02:14.800 Now we'll call this the level up requirement at level one. 02:14.800 --> 02:20.650 If you're level one, you have to reach 300 in order to level up to level two. 02:20.680 --> 02:28.450 Now, let's just say at level two, you must reach 900 experience before you can level up to level three. 02:28.570 --> 02:34.930 And let's just use the convention that we'll say the level up requirement at level two is 900. 02:34.960 --> 02:35.650 Be careful. 02:35.650 --> 02:39.970 This is where a lot of people start to get confused with the mathematics here. 02:39.970 --> 02:43.900 I'm saying the level up requirement at level two is 900. 02:44.020 --> 02:47.440 That's the total XP gained so far in the game. 02:47.440 --> 02:56.050 In other words, you had to gain 600 more XP after that initial 300 that you used to get to level two. 02:56.080 --> 03:04.390 Now let's say that the next level up requirement in order to get from level three to level four is 2700. 03:04.420 --> 03:07.630 Now again, that's only 1300 more. 03:07.660 --> 03:15.880 You reached level three, you had 900 total and then you got 1800 more, bringing that total up to 2700. 03:15.910 --> 03:20.890 So we're treating XP here as a cumulative total throughout the game. 03:20.890 --> 03:28.180 Now, if you wanted to, you could say that your level two requirement is 600 and your level three requirement 03:28.180 --> 03:29.590 is 1800. 03:29.590 --> 03:35.380 But the reason I like to do it the other way, keeping a cumulative total is because this allows us 03:35.380 --> 03:38.530 to handle situations when leveling up. 03:38.530 --> 03:43.240 That would be difficult to calculate and we'll talk about those in just a moment. 03:43.270 --> 03:49.980 Now, if you're a very mathematically inclined person, you're probably noticing a pattern here 300, 03:49.990 --> 03:52.090 900, 2700. 03:52.180 --> 03:54.130 That's a mathematical formula. 03:54.130 --> 03:57.250 And if you're sharp, you probably have figured it out. 03:57.250 --> 03:58.720 It's this formula. 03:58.840 --> 04:04.570 The requirement for any given level is 100 times three raised to the power of the level. 04:04.570 --> 04:11.020 At level one, your level up requirement is 100 times three raised to the first power or just 100 times 04:11.020 --> 04:11.730 three. 04:11.740 --> 04:15.970 At level two, your level up requirement is 100 times three squared. 04:16.000 --> 04:17.260 Three squared is nine. 04:17.260 --> 04:25.360 Nine times 100 is 900 at level three, 100 times three raised to the third, power gives 2700 and so 04:25.360 --> 04:25.860 on. 04:25.870 --> 04:32.260 So you may be tempted to say, well, we could just use a mathematical formula to dictate how much XP 04:32.290 --> 04:37.240 is required at any given level, and there's nothing wrong with doing it that way. 04:37.240 --> 04:42.730 That is actually a valid way in some games do use mathematical formulas. 04:42.760 --> 04:49.900 The problem with a mathematical formula is you're forced to stick to that formula unless perhaps you 04:49.900 --> 04:51.400 have multiple formulas. 04:51.400 --> 04:57.250 You could use this formula up to level three and then a different formula from level four on and so 04:57.250 --> 04:57.640 on. 04:57.640 --> 05:00.070 But that makes things a bit more complicated. 05:00.070 --> 05:05.740 And some games just choose these values by hand without a mathematical. 05:05.770 --> 05:06.400 Formula. 05:06.580 --> 05:11.110 Let's say that your level four requirement is 6500. 05:11.140 --> 05:18.220 In other words, you'd have to gain a total of 3800 more from your 2700 in order to get from level four 05:18.220 --> 05:19.420 to level five. 05:19.450 --> 05:22.660 Now, this doesn't adhere to this mathematical formula. 05:22.690 --> 05:28.150 If we stuck to the formula, it would be 100 times three raised to the fourth power. 05:28.540 --> 05:33.520 That would be a level requirement of 8100, not 6500. 05:33.550 --> 05:37.270 So I'm just pointing out that there are a couple ways to do this. 05:37.300 --> 05:43.690 You can use a mathematical formula and make your life easier, or you can do things in a different way 05:43.690 --> 05:46.180 that gives you more fine tuned control. 05:46.240 --> 05:50.110 And that's totally going to depend on the needs of your game. 05:50.910 --> 05:52.530 Now for this game project. 05:52.530 --> 05:56.580 I'm not going to use a mathematical formula for level up requirements. 05:56.610 --> 05:57.030 Why? 05:57.060 --> 05:59.940 Because I'd like them to be set by hand. 05:59.940 --> 06:07.200 And in addition to that, I'd like other values associated with our level up information, not just 06:07.200 --> 06:12.270 the XP requirement, but things like rewards for leveling up. 06:12.570 --> 06:19.980 For that reason, I like to use a data asset to keep this data driven and we can make one called level 06:19.980 --> 06:20.910 up info. 06:21.180 --> 06:29.370 Now this data asset is going to contain information for each level, and the most obvious piece of information 06:29.400 --> 06:34.380 per level is going to be that level up requirement and this could simply be an integer. 06:34.560 --> 06:42.000 So we can have perhaps an array of some kind of data structure that contains a level up requirement 06:42.000 --> 06:46.920 and we can have any other additional information in there, such as an attribute point reward. 06:46.920 --> 06:49.090 This could also be an INT 32. 06:49.110 --> 06:55.390 So each time we level up, we can look at the attribute point reward for that level and see how many 06:55.390 --> 07:01.140 attribute points we get rewarded and then we can spend those on our attributes to buff them up. 07:01.150 --> 07:07.210 Now I'd also like other types of rewards, such as a spell point reward so we could have a spell point 07:07.210 --> 07:07.900 count. 07:07.900 --> 07:15.100 And as we level up and get more spell points, we can spend those on either upgrading our spells or 07:15.100 --> 07:17.860 unlocking spells that we haven't yet acquired. 07:18.010 --> 07:25.090 This is a very common way to handle unlocking new content, so our level up info can also contain that 07:25.090 --> 07:26.620 spell point reward. 07:26.650 --> 07:31.080 So it's a data asset that's kind of simple, kind of basic. 07:31.090 --> 07:37.090 It's an array of structs that contain integers, but it's a nice way to sort things out and it also 07:37.090 --> 07:43.210 allows us to handle complications associated with the mathematical formula method. 07:43.420 --> 07:45.700 And we'll talk about that in a second. 07:45.730 --> 07:52.330 Now, the data asset should also have an easy to use function for looking up what level we should be 07:52.330 --> 07:55.240 at for any given XP amount. 07:55.270 --> 07:57.740 Now, how would a function like this work? 07:57.760 --> 07:59.440 Well, let's talk about that. 07:59.770 --> 08:04.140 Let's say that for each level we have level requirements. 08:04.150 --> 08:09.610 In other words, if we know how much XP we have, we know what level we should be. 08:09.640 --> 08:16.150 Now let's say that we're playing our game and we've reached an XP total of 180 so far, so we haven't 08:16.150 --> 08:16.960 leveled up yet. 08:16.990 --> 08:19.600 We're still level one right now. 08:19.600 --> 08:24.250 Let's say we just happened to defeat a higher level enemy. 08:24.280 --> 08:31.130 Perhaps we're just that good and that enemy gives us a lot of XP, say a thousand points. 08:31.150 --> 08:33.300 What happens in this case? 08:33.370 --> 08:41.560 Now we only needed 120 more XP points to level up to level two, but a thousand is far more than that. 08:41.590 --> 08:45.240 A thousand puts our total at 1180. 08:45.250 --> 08:47.430 That means we're right here. 08:47.440 --> 08:50.920 We have enough experience to be level three now. 08:50.920 --> 08:54.370 In other words, we've just achieved a double level up. 08:54.870 --> 08:57.640 Now, this is not as uncommon as you might think. 08:57.660 --> 09:05.070 This happens all the time in games, and that's the whole fun of RPGs is you start to get more powerful 09:05.070 --> 09:12.450 and more capable of defeating higher level foes that reward you with more experience points. 09:12.540 --> 09:18.810 So it would be a serious shortcoming if you did not account for this in your code. 09:18.840 --> 09:21.270 So we'll make sure that we account for it. 09:21.300 --> 09:27.360 Now, I mentioned complications with using mathematical formulas as opposed to data assets. 09:27.450 --> 09:35.130 A formula could be used to calculate Exp requirements, but this makes the mathematics a little bit 09:35.130 --> 09:41.410 cumbersome to handle things like double level ups or perhaps triple or quadruple level ups. 09:41.430 --> 09:44.610 You see, you'd have to jump through mathematical hoops. 09:44.640 --> 09:49.680 You'd have to take the player's current level, which would be one, and plug that into the formula 09:49.680 --> 09:54.210 to see how much more experience they need to level up to level two. 09:54.240 --> 09:59.890 Then you'd have to plug two into the formula to see how much would be required to level up to level 09:59.890 --> 10:07.330 three and check the current amount of experience being received and see if it's enough to do a double 10:07.330 --> 10:08.140 level up. 10:08.170 --> 10:13.180 You'd also have to check to see if this was a triple level up and so on and it gets a little bit out 10:13.180 --> 10:13.870 of hand. 10:13.900 --> 10:19.990 Whereas if we have a data asset, we can simply write a neat little algorithm that will check for double 10:19.990 --> 10:21.250 and triple level ups. 10:21.250 --> 10:24.430 So we'll be talking about ways to handle this situation. 10:24.430 --> 10:29.320 So we have a number of steps moving forward to implement Exp and leveling. 10:29.410 --> 10:36.970 First, we need to create a level up info data asset where we can specify level up requirements for 10:36.970 --> 10:43.900 each level as well as any rewards that can be gained as a result of leveling up, such as attribute 10:43.900 --> 10:45.370 points and spell points. 10:45.880 --> 10:47.680 Now we need XP. 10:47.950 --> 10:53.260 And while XP could be an attribute, that's one way to implement it. 10:53.290 --> 10:59.320 I personally think it makes more sense for this not to be an attribute, but rather a value on the player 10:59.320 --> 11:00.040 state. 11:00.160 --> 11:07.300 Attributes are values that affect the game in various ways, such as affecting combat, and they're 11:07.300 --> 11:13.100 great for when you need interoperability between various elements of gas. 11:13.120 --> 11:20.710 But in the case of XP, all it really is is a mark of progress and something we check to see whether 11:20.710 --> 11:22.720 or not it's time to level up. 11:22.750 --> 11:30.130 We don't really use XP in our combat calculations, for example, so I personally think it's better 11:30.130 --> 11:31.780 not being an attribute. 11:31.810 --> 11:36.910 However, you may disagree and feel like it should be an attribute and that's fine. 11:36.910 --> 11:41.020 And this course project though, we're going to put it on the player state. 11:41.050 --> 11:43.690 Now we're going to need it to have a rep notify. 11:43.720 --> 11:49.580 So that way as we set it on the server and it should only be set on the server, we can replicate it 11:49.580 --> 11:53.840 to clients and that way its changes can be reflected in the HUD. 11:55.080 --> 12:01.050 Now we're going to need a delegate to broadcast when the XP changes, and that way our widget controller 12:01.050 --> 12:07.740 can respond to that delegate broadcast and update any widgets such as our XP bar and the HUD. 12:08.760 --> 12:11.460 Now we also need an XRP reward. 12:11.490 --> 12:15.870 The amount of XRP gained each time we kill an enemy. 12:15.870 --> 12:20.880 And this can be based on the enemy's level and its class or anything else we want. 12:20.910 --> 12:25.410 But we need to know how much XRP any given enemy is going to give us. 12:26.220 --> 12:30.210 And then we actually need to award that XP when killing an enemy. 12:30.240 --> 12:38.670 Now, this is going to be closely related to our systems in gas as when things happen, such as applying 12:38.670 --> 12:41.360 gameplay effects and changing attributes like health. 12:41.370 --> 12:45.670 That's when we can determine whether or not damage was fatal. 12:45.690 --> 12:52.680 So even though XP is not going to be an attribute, that's not to say that we won't have some kind of 12:52.680 --> 12:59.280 attribute that we can update in order to make those XP calculations something like a meta attribute 12:59.280 --> 13:02.400 as that's what our incoming damage attribute is. 13:02.460 --> 13:04.120 So we'll get to that. 13:04.140 --> 13:09.930 And finally, we have to actually handle leveling up and potentially handle multiple level ups. 13:09.930 --> 13:17.370 As we mentioned before, we may defeat an enemy that gives us enough XP to double or even triple level 13:17.370 --> 13:17.730 up. 13:17.730 --> 13:20.460 We need to handle that potential situation. 13:20.460 --> 13:27.700 And along with leveling up, we need to reward our player with any rewards that we decide we should 13:27.700 --> 13:30.880 get, such as attribute points and spell points. 13:31.000 --> 13:33.670 So leveling up is quite a system. 13:33.670 --> 13:38.860 It's not terribly complex, but there are a lot of parts to it that we have to keep in mind. 13:38.950 --> 13:44.860 But once we get this system in place, it's going to really bring our game project to that next level 13:44.860 --> 13:52.780 as we have that sense of progression and as the player gains progress, they can then become more powerful 13:52.780 --> 13:55.630 and move on to higher level enemies. 13:55.630 --> 13:56.590 Dungeons. 13:56.590 --> 13:57.580 ET cetera. 13:58.300 --> 14:01.240 So we'll implement this system in the videos to come. 14:01.390 --> 14:02.620 I'll see you soon.