1 00:00:04,500 --> 00:00:05,580 ‫Hello and welcome. 2 00:00:05,580 --> 00:00:12,360 ‫In this lecture, we're going to be adding variables to our moving platform actor so that we can see 3 00:00:12,360 --> 00:00:16,560 ‫them in the editor and we're going to be doing this entirely in C++. 4 00:00:16,560 --> 00:00:17,790 ‫Let's dive in. 5 00:00:18,360 --> 00:00:23,640 ‫So the first concept that we're going to be learning in C++ is how to create variables. 6 00:00:23,640 --> 00:00:25,890 ‫We've seen them before in Blueprint. 7 00:00:25,890 --> 00:00:30,090 ‫We know that they're like boxes that we can put values into and that they have types. 8 00:00:30,240 --> 00:00:34,890 ‫Well, all of that still applies over in C++, except how we create them. 9 00:00:34,890 --> 00:00:39,810 ‫So previously, when we did this in Blueprint, if I go and open up a level blueprint just to show you 10 00:00:39,810 --> 00:00:45,150 ‫and refresh your memory, then we had this, my blueprint pane, and that was where we added things 11 00:00:45,150 --> 00:00:48,300 ‫like functions and variables and so on. 12 00:00:48,300 --> 00:00:51,510 ‫And then we had the event graph where we actually program stuff in. 13 00:00:51,510 --> 00:00:53,970 ‫Now C++ is very similar. 14 00:00:53,970 --> 00:01:00,270 ‫We have two different locations for doing the configuration of our variables and functions and then 15 00:01:00,270 --> 00:01:02,190 ‫when we actually do the implementation. 16 00:01:02,190 --> 00:01:07,500 ‫So let's go over to Visual Studio code and open up the Visual Studio Code Project and have a look. 17 00:01:07,500 --> 00:01:10,650 ‫In the left hand bar there is an Explorer tab. 18 00:01:10,650 --> 00:01:16,710 ‫Go and open that up and you can see basically a hierarchical map of your files. 19 00:01:16,710 --> 00:01:22,800 ‫So we've got at the top level five and Obstacle Assault or our own project here, you can open that 20 00:01:22,800 --> 00:01:24,300 ‫up and you can see some of the folders here. 21 00:01:24,300 --> 00:01:28,410 ‫The one we're interested in is the source folder, which is where we can find all of our C++. 22 00:01:28,410 --> 00:01:34,800 ‫Then in there there is the obstacle assault folder and then there's two files with the name of moving 23 00:01:34,800 --> 00:01:35,340 ‫platform. 24 00:01:35,340 --> 00:01:44,250 ‫One is a dot file and one is at DOT CP, the DOT stands for Header and CP it stands for C++. 25 00:01:44,250 --> 00:01:52,170 ‫So this is essentially a bit like having a my blueprints where you can add in the functions and variables 26 00:01:52,170 --> 00:01:58,710 ‫and stuff that is resides in the header file, the FF file, and then we have the dot CP where we can 27 00:01:58,710 --> 00:02:03,060 ‫actually essentially like the event graph, we can actually do the coding itself. 28 00:02:03,330 --> 00:02:06,600 ‫So we're going to open up the moving platform. 29 00:02:06,840 --> 00:02:12,180 ‫H Because we want to add in a new variable and you'll notice that there's a whole bunch of stuff in 30 00:02:12,180 --> 00:02:12,300 ‫here. 31 00:02:12,300 --> 00:02:18,180 ‫We're not going to go into the details of this, but what is most interesting is that it is defining 32 00:02:18,180 --> 00:02:20,910 ‫what it means to be a moving platform class. 33 00:02:20,910 --> 00:02:23,370 ‫You can see a couple of keywords here that are interesting. 34 00:02:23,370 --> 00:02:25,290 ‫There's a class keyword on line ten. 35 00:02:25,290 --> 00:02:32,160 ‫There is the moving platforms which is prefixed with an A, meaning that it's an actor, and then there 36 00:02:32,160 --> 00:02:36,270 ‫are some curly braces on line 11 and 26. 37 00:02:36,270 --> 00:02:42,540 ‫And between these matched curly braces, you can see there is the declaration of a few things. 38 00:02:42,540 --> 00:02:46,200 ‫There are functions in here and this is where we can also put our variables. 39 00:02:46,440 --> 00:02:49,680 ‫So we're going to add our variables to the end of this declaration. 40 00:02:49,680 --> 00:02:57,030 ‫So just before we close that curly brace, we can add some new lines and start writing our new variables 41 00:02:57,030 --> 00:02:57,810 ‫in here. 42 00:02:58,140 --> 00:03:02,970 ‫And just like in a variable in blueprint, we have a type and we have a variable name and we can also 43 00:03:02,970 --> 00:03:04,440 ‫give it a default value. 44 00:03:04,620 --> 00:03:13,530 ‫So the first thing is we want to maybe create an integer and in C++, in Unreal C++, an integer is 45 00:03:13,530 --> 00:03:20,550 ‫denoted with the keyword INT 32 basically telling us how big a value we can store in here. 46 00:03:20,550 --> 00:03:22,500 ‫And no, it's not 32. 47 00:03:22,530 --> 00:03:23,820 ‫It's much, much larger than that. 48 00:03:23,820 --> 00:03:28,620 ‫32 is the number of bits allocated to the integer. 49 00:03:28,650 --> 00:03:33,750 ‫Now we've got to go for a variable name and just like the classes, we cannot have spaces in our variable 50 00:03:33,750 --> 00:03:34,200 ‫names. 51 00:03:34,200 --> 00:03:38,670 ‫So instead we use capital letters to denote our words. 52 00:03:38,670 --> 00:03:41,520 ‫So I'm going to call it my int notice. 53 00:03:41,520 --> 00:03:44,520 ‫I'm capitalizing both of the beginnings of those words. 54 00:03:44,520 --> 00:03:50,730 ‫Then I can give it a default value and we do this with an equal sign so we have equals, and then we 55 00:03:50,730 --> 00:03:53,970 ‫can give it a value such as 99, for example. 56 00:03:54,150 --> 00:03:59,880 ‫Now notice that I'm putting spaces after my and before my equals sign. 57 00:03:59,880 --> 00:04:04,140 ‫That's not actually strictly necessary, but it does make it easier and nicer to read. 58 00:04:04,140 --> 00:04:05,760 ‫So I include that. 59 00:04:05,760 --> 00:04:11,070 ‫Now you do obviously need a space between the 32 and the actual name of the integer. 60 00:04:11,070 --> 00:04:12,690 ‫Without that, things don't work. 61 00:04:12,960 --> 00:04:18,210 ‫And then to finish off this declaration, you need to put a semicolon on the end of the line to tell 62 00:04:18,240 --> 00:04:20,520 ‫C++ that you are done. 63 00:04:20,520 --> 00:04:26,010 ‫The fact that there is new lines and that there are spaces and tabs, all of this doesn't actually matter 64 00:04:26,010 --> 00:04:26,790 ‫to C++. 65 00:04:26,790 --> 00:04:30,360 ‫You could run all of this stuff together and this would still be the same. 66 00:04:30,360 --> 00:04:34,230 ‫I could take out the spaces here that would still work just fine. 67 00:04:34,230 --> 00:04:38,040 ‫As far as C++ is concerned, this is all perfectly valid C++. 68 00:04:38,040 --> 00:04:40,590 ‫It's just really awful, awful to read. 69 00:04:40,800 --> 00:04:46,350 ‫So what we do is we keep this level of indentation with a tab and we keep this level of spacing as well 70 00:04:46,350 --> 00:04:48,000 ‫just for our sanity. 71 00:04:48,450 --> 00:04:52,380 ‫Now this isn't currently visible over in the Blueprint Editor. 72 00:04:52,380 --> 00:04:57,540 ‫To make it visible, we need to give a little bit of a heads up to Unreal that there is a variable it 73 00:04:57,540 --> 00:04:58,410 ‫should display. 74 00:04:58,410 --> 00:05:03,770 ‫The way we do this is on the preceding line we type you property all caps. 75 00:05:04,330 --> 00:05:11,170 ‫Then open parentheses and then using our what's called camel case, basically where we capitalize the 76 00:05:11,170 --> 00:05:17,460 ‫first letter of each word we type edit anywhere like so, and then we close the parentheses. 77 00:05:17,470 --> 00:05:19,420 ‫No need for a semicolon at the end of this line. 78 00:05:19,420 --> 00:05:26,050 ‫That's not correct, because it's actually part of the same declaration as the integer down on the line 79 00:05:26,050 --> 00:05:26,770 ‫below it. 80 00:05:27,160 --> 00:05:32,470 ‫But we put them on separate lines just to make our life easier for reading this. 81 00:05:32,470 --> 00:05:39,100 ‫So we've got you property edit anywhere in 30 to my int and then equals sign and then 99. 82 00:05:39,100 --> 00:05:42,790 ‫And it's important that you save your files here by default. 83 00:05:42,790 --> 00:05:44,980 ‫You need to hit control as to do this. 84 00:05:45,100 --> 00:05:51,160 ‫If you go to the file menu, you can hit autosave here as an option so that you don't have to hit save 85 00:05:51,160 --> 00:05:52,660 ‫every time you change things. 86 00:05:52,750 --> 00:05:53,890 ‫Now that's what I do. 87 00:05:53,890 --> 00:06:00,190 ‫So with that done, we could go ahead and close the editor, recompile and re-open it and we would have 88 00:06:00,190 --> 00:06:03,100 ‫a new variable on our moving platform. 89 00:06:03,100 --> 00:06:08,560 ‫Actor But that's a bit of a pain if we had to close the editor every time we made a code change. 90 00:06:08,560 --> 00:06:12,160 ‫So there is a feature in Unreal called Live Coding. 91 00:06:12,160 --> 00:06:18,130 ‫I'm just going to go and close down the level blueprint and show you that there is a button down in 92 00:06:18,130 --> 00:06:21,970 ‫the bottom right which looks like a set of cubes dissolving off into the distance. 93 00:06:21,970 --> 00:06:27,790 ‫If you hover over it, it says recompile and reload C++ code for games on the fly, click that button 94 00:06:27,790 --> 00:06:36,340 ‫and a terminal will show up with a log of messages that are the results of compiling your code. 95 00:06:36,730 --> 00:06:41,380 ‫Now, this will run a lot faster than it previously did because it's not the first time it's running, 96 00:06:41,470 --> 00:06:46,210 ‫and when it's complete, it's going to give you a notification saying that live coding succeeded. 97 00:06:46,450 --> 00:06:53,650 ‫Now it's important that if live coding didn't succeed, that you copy the results of the log that come 98 00:06:53,650 --> 00:06:59,530 ‫before the error and post those in the Q&A if you need to ask for help, but also just double check 99 00:06:59,530 --> 00:07:03,340 ‫and make sure that your syntax matches what I've typed on screen. 100 00:07:03,520 --> 00:07:09,910 ‫Oftentimes we will find that it's simply a typo that people have made and it doesn't compile because 101 00:07:09,910 --> 00:07:10,630 ‫of that. 102 00:07:10,630 --> 00:07:18,550 ‫Pay close attention to your capitalization as capitalization is often very important and also your semicolons. 103 00:07:18,550 --> 00:07:20,950 ‫People often forget to include those. 104 00:07:21,100 --> 00:07:26,200 ‫So now I'd like to challenge you to add your own variable on a new line in that header file. 105 00:07:26,200 --> 00:07:30,190 ‫So make it a float or bull type and give it a different name. 106 00:07:30,190 --> 00:07:32,020 ‫Variables cannot share the same name. 107 00:07:32,020 --> 00:07:33,100 ‫They have to be different. 108 00:07:33,340 --> 00:07:34,990 ‫Give it a default value. 109 00:07:34,990 --> 00:07:38,050 ‫So if it's a float, the default value needs to be of the format. 110 00:07:38,050 --> 00:07:39,970 ‫Something point, something, something. 111 00:07:39,970 --> 00:07:47,560 ‫If it's a boolean, it needs to be either true or false all lowercase recompile using live coding and 112 00:07:47,560 --> 00:07:53,860 ‫then see if you get any errors and if you do come back and see how I do it to double check that you've 113 00:07:53,860 --> 00:07:55,210 ‫written it the right way. 114 00:07:55,300 --> 00:07:57,250 ‫Pause video and have a go. 115 00:08:00,500 --> 00:08:00,890 ‫Okay. 116 00:08:00,890 --> 00:08:01,790 ‫Welcome back. 117 00:08:02,060 --> 00:08:06,440 ‫So let's go back into Visual Studio code and we're going to add a variable. 118 00:08:06,440 --> 00:08:09,470 ‫So first of all, we're going to be making it a new property. 119 00:08:09,470 --> 00:08:13,400 ‫It's open parentheses and edit anywhere and close parentheses. 120 00:08:13,400 --> 00:08:19,670 ‫Then on a new line, I'm going to make it a float type and we're going to call it my float just to keep 121 00:08:19,670 --> 00:08:21,530 ‫up the tradition here. 122 00:08:21,620 --> 00:08:27,320 ‫And we're going to give it a default value of 5.99 and then put a semicolon at the end of the line, 123 00:08:27,320 --> 00:08:31,420 ‫make sure that you have all of the components of what I've just typed in here. 124 00:08:32,060 --> 00:08:34,130 ‫Then I'm going to add some more spaces. 125 00:08:34,130 --> 00:08:36,980 ‫Notice that I'm adding multiple new lines. 126 00:08:36,980 --> 00:08:39,110 ‫It doesn't really matter how many new lines you have. 127 00:08:39,110 --> 00:08:40,670 ‫Whitespace doesn't matter. 128 00:08:40,670 --> 00:08:44,750 ‫As I've said, then we're going to have a new property again. 129 00:08:44,930 --> 00:08:51,920 ‫Edit Anywhere that's going to be of type bool and I'll call that my bool and I'm going to give it the 130 00:08:51,920 --> 00:08:55,760 ‫default value of true and put a semicolon on the end there. 131 00:08:55,760 --> 00:08:58,340 ‫Now you don't have to save if you've got autosave, but you do. 132 00:08:58,340 --> 00:09:01,220 ‫If you don't, then we go back into the editor. 133 00:09:01,220 --> 00:09:09,080 ‫We hit the live coding button in the bottom right and the log will come up and hopefully we'll succeed, 134 00:09:09,200 --> 00:09:10,700 ‫which it has done for me. 135 00:09:10,700 --> 00:09:16,490 ‫But I just want to show you what would happen if I'd made a mistake, such as leaving out the semicolon 136 00:09:16,490 --> 00:09:20,300 ‫and the end of this line instead of a nice, reassuring green. 137 00:09:20,300 --> 00:09:25,550 ‫At the end of the log you will have a red build failed showing up instead. 138 00:09:25,550 --> 00:09:31,520 ‫So this is important that if you get a build, fail, first things first, go and check your code, 139 00:09:31,520 --> 00:09:38,030 ‫make sure it matches mine, because as I've said, it's often just a typo and if not, then copy this 140 00:09:38,030 --> 00:09:42,290 ‫and put it in the Q&A and ask for some help. 141 00:09:42,350 --> 00:09:49,220 ‫That said, I'm going to correct my code now and recompile it, and when that has succeeded, I can 142 00:09:49,220 --> 00:09:56,180 ‫close down the log and I can look in the outline for the moving platform, and I can select the moving 143 00:09:56,180 --> 00:10:00,590 ‫platform to look in the details pane and see all of the variables that I've created. 144 00:10:00,590 --> 00:10:07,040 ‫They my int the my float and the my bool and the default values that we have given them there. 145 00:10:07,040 --> 00:10:10,040 ‫Now, it's worth noting that these are indeed just defaults. 146 00:10:10,040 --> 00:10:16,730 ‫So if you were to override those values in the editor, in Blueprint or in the level, and then you 147 00:10:16,730 --> 00:10:21,110 ‫go and change them in C++, the changes in C++ will no longer have an effect. 148 00:10:21,110 --> 00:10:22,580 ‫They were only default values. 149 00:10:22,580 --> 00:10:28,580 ‫So if you've made changes in Blueprint, that takes precedence and overrides anything you did in C++. 150 00:10:28,610 --> 00:10:29,360 ‫Fantastic stuff. 151 00:10:29,360 --> 00:10:35,420 ‫We've created our first variables, our first code in C++ and brought it in using live coding. 152 00:10:35,420 --> 00:10:37,250 ‫I will see you in the next lecture.