Rust Programming Language Game Development, 13 May 2017

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From YouTube: Lisa Passing - Making a game in Rust

Description

When you’re trying to learn a new programming language it makes sense to start with a small project. A lot of developers would write an API server or a Twitter bot. When I try to learn a new language I start by writing a game. Let me show you how I wrote my first game in Rust with Piston.

Lisa Passing
https://lislis.de/
https://github.com/lislis
https://users.rust-lang.org/users/lislis/activity

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Work: okay, yes, microphone checks, welcome everyone, I hope lunch was great. My lunch was great, even though sitting at the vegetarian table was a bit awkward.

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Nonetheless, we're going to talk about making a game and rust I don't have a lot of time and so I'm going to make everything like quite short and but try not to race through it. So I'm, this or Lisa or Liz's and I think I'm. The only speaker whose handle is on the schedule and not like real name, but it's fine, I work, a travesty I and we do continuous integration. I dropped, a bunch of stickers and I.

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Think there's still some left yeah, but my day job mostly consists of front-end work, so javascript in the browser and pushing pixels I actually like CSS. Believe me: I do nonetheless I have a different hobby, and that is everything about video games playing and for this talk, more importantly, making video games. So you might wonder why I'm making video games like the programming is awesome like do this as a hobby. Well, there's a couple of reasons.

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One of them is like making games can be seen as like and like art of like artistic expression, like some people make song some like as a hobby or they paint, and you can also make like weird little video games without experiences or like feelings and there's this whole niche on the Internet, where people do these kinds of things and also I, think there that games are programmatically quite challenging because they're so different from web programming.

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So there's like a couple things that you need to consider that, just like don't appear in my day, job which is I find like this is something that's really interesting and also on the challenging part of size. This, like it's not just like the logic of the game, that you need to take care of their selves like graphics and they might be sound and hopefully their sound and like interaction, but that just like interaction player with like your game software, but this could also mean interaction with hardware.

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Do you use a keyboard or I have made a game that uses an immediate eboard so like an actual like piano like keyboard as an input device and like all these kinds of things that you can like be creative about and can like toy around with. So everything is basically about fun in learning stuff. So now you know why we should make a game. Why would you want to use rust for it?

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So generally, it's like people won't say to me like Oh, like I'm gonna, make games like what language should that should I write them in I, usually say like for the scope of like an indie game, any language we do ethnic games in Lua and Ruby and JavaScript in closure, and it's all fine like because until like speed and like all these things actually matter like you, don't have the time to the game. That is that complex that you actually care about these things.

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That being said, like the big titles that you play on PlayStation or on your xbox or pc, or whatever they usually code it in C and C++, where the engineers try to like get every computation out of every clock cycle and it's like very, very low level and like hard on the on the actual hardware of the system and well all the rest of the system of the language I was like. Oh, we could actually like think about making big titles in rust.

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Also Brussels, new and shiny and I always try to like learn things, and this was like the perfect opportunity to like get interested like okay. I can make a game in it. um Here's a brief intermission because, like I started researching like how to make games like a few years ago, and every book I ever read on it at code, examples in C++ and while it was fine like reading the book and I'm like reading the narrative to like the cows like yeah I can sort of follow it. I was like I cannot.

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I cannot code this on my own, so I, like years ago, I tried learning C++ like the hard way and there's a series about it, but it was actually hard- and this was mostly because, like every time, I was stuck and I didn't understand something. I asked like programmers that I know from like various communities like Isis problem in C++. You studied computer science, like you sure, know how to solve this and like don't you want to like try. Ruby, maybe like I, can explain your Ruby I.

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Think no, but like I need help in c, plus plus something ya know so I stopped and never learned C++. So this sad story, the positive story expect to the wire you thrust. People are excited about it and then, if it tells people, oh like I'm, trying to make a game and rust they're like awesome, tell me all about it.

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It's like I, actually, don't know what I'm doing, but I can tell you about it and, as part of like the welcoming community that you are and we've like heard it a couple of times during the day. This is not like a given for other communities and I think it's really exciting. This is like probably what will make me stick around in the rest community.

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So all this aside, it's actually make a game um to make a game. You usually need three things. um You want to use an engine because if you don't use an engine and you start making a grain game from scratch, you will end up making a game engine um people are laughing is like I was like yeah, and so, if you want to make a game, you pick an engine probably- and you might wanna have an idea.

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What the game is about could be anything and then you need time to make it because making games is quite the time consumer and I like to do games at game jam. So it's just like focused like one or two days and then I've done never touch it again, but you learn a lot still.

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Okay, picking on engines- and this is very cool site that I found, which is called. Are we game yet calm, which lists yet game related resources in the rust ecosystem? So crate said you might want to use this of games that are already out. There was like perfect. This is just what I need so I went to the list of game engines and I picked the first one piston which like for some reasons it seemed kind of cool. It's for the short lifetime of rust itself.

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Piston has been around for quite a long time and it's still very actively like maintained and developed, and just like now. This is a good indicator. I like like the modularity approach that says that we have a couple of like small focus, crates that you can use in like pluck your engine together. So there's like modules that you can use for 3d stuff, but I will focus on the two details like other. This is cool, so in case I end up learning, 3d modeling at some point, I could still use the same engine.

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um There's already like a few games listed on the on the wiki that use piston. Most of them are snake or Tetris, but that's those are still valid games and there's a couple of like new one.

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So there's like some called some code in the wild that I could take a look at and the documentation could be better they're sort of like generator talks, but as a beginner I was like I, don't really like the list of traits that this thing implements doesn't really tell me anything because I was too lazy to read to the point in the book where it's about traits, so I don't know, but that's okay, because I could form them away through it with the example games and saying like oh so, how do they use it?

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All this way, so you'll be fine. um Honorable mention for an engine called GG, easy good games, easy I think is what it stands for and because they describe like their their mission or their design. Inspiration was love 2d, which is a very popular 2d game engine in Lua, so every game engine that tries to be like love, 2d, is probably on a very good way and I would probably try it next for the next game. Okay, we have our engine.

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Now we need to get an idea and just like, as I already said, it could be about anything. You want an experience. Just make games about a joke that I heard and like it could be anything so. The game that I made for this talk is called Montana attack. Montana is Spanish for Apple and it's based on a true story which I'm going to tell you.

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Otherwise, you won't really get the game and I was in Spain a few months ago with my partner and we're visiting like a colleague of mine, who's based in in Madrid in Spain, and we were out like having a beer sitting outside a bar and just like chatting when all of a sudden and an apple came falling down and crashed into my co-workers backpack and make this like sound and like pieces of Apple like flying everywhere and we're like well what is happening and was like one Apple and then it was silent and were like.

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Where did that come from looking up no tree likes like the next tree, was like ten meters away and was an olive tree. What and we like looked up at the buildings like someone just threw an apple out of the window with like not caring at all. For, like what happens, it was like it wasn't. Just like you know, a piece of Annapolis like an entire Apple. We like looked at the scraps, açaí quiet and it was very surreal and the next day is like.

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Oh I should probably make a game out of this because it was so weird, so I went back to the house or the bar where this happened and took a picture which is like in the game which I'm going to demo right now, which hopefully works so I'm gone, no I'm. Probably me too.

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And you can see this, oh, this is actually huge in this resolution and okay. So, despite the fact that the the contrast isn't very good, so the sesemann sound and take it's like a little window, 500 by 700 pixels, it says WASD to move and M to throw em for Manzana, obviously and also M to start.

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So what you see is the house wares actually happened, and it happens that the windows of the house make this nice three by four grid, in which me the player represented by the black square, is moving around and you see down at the floor. There's red rectangles, walking from right to left left to right at various speeds, so I can move around and when I press, M, F or an apple, damn it so like. Here. Your game is to like time these and like actually hit the people.

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You see at the top that you have a meter of ten apples and if you throw an apple like those decreases, and then you get a score or if you actually hit right now, you always get 20 points which is very random, because I couldn't decide on like a proper logic for scoring so I'm going to play this real, quick and just like hope that I get a lot of.

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Okay, when I'm out of apples or like the last apple hits the bottom or a person at the bottom, I get the ending screen so I'm out of apples, a head score of congregated, ad I, think and then press escape to leave, which I'm going to do- and this is the game.

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Thank you, let's quickly run through. How would you build such a thing? So here's an ingredients list also known as cargo tunnel and I have only three dependencies which are piston window, fine folder for like finding efforts and random for all things, randomness, and you might wonder why it's only piston window. Didn't you talk about like modularity in crates and stuff piston window. Is a convenience wrapper that like when you're starting you don't have no choice like what crate or like what back-end for Windows?

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Do you want to use like I, don't know so piston windows there to like gives you like a nice choice of things that you probably want to use which I use. This is like nice. It's nice try to flight okay. They made some choices for me because, as a complete, beginner, I, don't know so in later games, you can like start using the goop core, piston engine and then put stuff together as you go.

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Okay, let's quickly talk about some other game fundamentals and a game usually consists of like four four main parts and that you need to consider. One of them is load which is like initializing, your window, loading all the assets and all that stuff, and then you have update and render, which are most engines they're like callbacks or events that happen 60 times a second. So in render you just like draw stuff and because it happened so fast that are the human eye cannot see that you like redrawing this very fast.

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You see this movement because, like value slowly, change and the change of values is usually computed in the update cycle, which also happens 60 times per second. Hopefully, what makes this thing interesting? So all of this would make super awesome, generative, art and the things that makes it a game is like events or inputs where we interact with the game. So I am in my game, like I, move around the player and press em to throw up the Apple.

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So let's look at some code- and this is a boiled down version of my a Maine RS. We just say like extinct, right, piston and use system window everything there's like in the code on github. You can see that there's also like the random crate and then find folder, but this doesn't matter right now and in the main function.

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What we need to do is specify a version of OpenGL then create a piston like a window with shaft, which is of type piston window and I. Given some settings like the title of the window, the width and height that we want, it would give the version of OpenGL.

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You say if you want to exit on escape, it can say true, which is what I used and then built and then unwrap, and then you have like our piston window for the game and the actual nice thing happens next, which is a while loop and that iterates over all the events that the window for was at us. So the piston window would give us all the events that happen, and then we have like a match statement where we like sort these events. Okay, is this an update event then do this or like?

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Is it a render event or is it an release event and in my game, I only use release events because that's worked for me, but you can also use I, keep press events or mouse button, click, events or scrolling or just mouse movement and other things are supported, but I just need these and the rest of them like happens. Basically inside of these event, hooks I would call them, maybe so far so good. Let's take it look at the structure.

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I made a couple of structs. Most of them are just there to keep track of the positioning within the game, so just like absolute pixel values, so I have the main game struct, but I should probably say that folk or the folks in the game are the red squares or the people that walk around the street. So the game main games track keeps track of or like contains the vector of folks or a folks vector of folk of type folk and and the player and the player then has shops and apples shots.

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Earth was the indicator that was at the top.

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That tells you, oh yes, like 10 apples, and if you saw an apple, you have nine left, and then you have eight left and keeps track of this and like Apple structs are just like the literal apples that fall down the house and then maybe hit people yes, sort of, like the respected pet destructor I created, there's a quick walk through because something already like hard on the time limit and ever said in the loading we like initialize, the video initialize, the window, the game and load all the assets assets quickly, like all the image files, the fonts and all that kind of stuff render is just literally iterate over every vector and like draw all the information that we have in form of either images or like squares or like points in the score where we type text and eventual kind of interesting, like I use relief.

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And so we check, if, like we, get Pistons received like events for every button that is pressed and I just like match it. To say if this is actually cam.

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The key M like then only then call the throw and on the player struct I have a throw method that there's some code that calculates the new position of the Apple that is going to be thrown, and then we call just like self shop start fire which is like on the shop struct or like in the shops. Thing decreases. The counter and in the echo vector, are just like push a new Apple that will then be updated by the update loop, but to go to that and one in a second.

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This is like actually really simple code in the update.

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This is where most of the magic happens, because we update all the things on the Apple struct for every Apple runs its own update and I'm checking for if the Apple itself is active and then I'm going to just decrease the value of like the y-axis, which is the one that there is the vertical one and we start we're at the top and it froze when you go towards the bottom so like on every update I'm just going to like increases by one which is kind of random.

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But it works and then I'm going to check if the the value exceeds a certain amount which, aside towards the I'm gonna kind of deactivate the Apple instead of to false. And so then like the apples, inactive. So similar thing happens when I update the folks that run around the street also going to like check. If the fog is still active and then I have the property on them, which is called ltrs or left to right, which is either true or false.

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So and when they come from the right side or from the left side difference whether I need to increase or decrease the value on the x-axis and also depending on that, I have the condition for when to like the activate from like when they walk out of the the screen. Basically, yes, I also at the time like a time mechanic for spawning new folks, which is right now directly in the game, structs updates methods, which would probably go to like a folk controller, abstraction thing.

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But it was so small that I just put it in there, which is like just a counter that takes the Delta time and Delta. Time is the time between two coils of like the update function.

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So this is like somewhere in the milliseconds like sphere and just like call up all the milliseconds, and if the counter is like greater than some interval, that I chose, for example, I, think it's two seconds or in the game every two seconds a new person respond somewhere and like if we actually like, if the two seconds are exceeded, I'm going to reset the counter. So I can like start from zero and the next and the next round, but I'm also going to call self spawn folks.

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So like a new folk is pushed into the ends of the games. Folk vector and like the spawn method itself. Like just does all the random stuff like choose a random direction like either go from left to right and like what speed? You should walk it, because the speed is also varying a bit and what's also happening on. Every update loop is checking for collision, which is this very verbose.

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Code of two nested for-loops imma draining over all folks and check is like they're, still active and then I'm going to iterate over all the apples and check of the Apple estate active, still active, and then there's like a collision detection of like two rectangles, which is very nice. If you just use rectangles, because the geometry for overlapping rectangles, with where the XS are lined in the same way, is fairly trivial to just six like this, with like greater than the other widths.

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And then it's just like four lines in the fifth statement and and if those match, so if the rectangles actually overlap kind of deactivates, both the folk and the Apple, which is also like setting the active flag to false and then this is also where the scoring should happen. Ideally, but yes, scoring is a different thing.

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There's a couple of things that I do not like about this game. At the moment they were missing and had sound effects. I I already picked the sound effects there in the git repo, but I couldn't make the Krait ears to work for ears. Just the crate was like a little like load, some sound acid and then play it, but it didn't work. I'm, blaming I tried, install supercollider on my computer, which is like this gigantic music library, and it didn't work at all and I'm blaming this. For that.

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So not sure if this ever works, I really want is sophisticated, scoring logic based on the height of the upper and where you from where you drop it and the speed of the folk that she actually hit. So if you have a Apple that you throw from higher up the building and exponentially hit like a very fast-moving folk at the bottom, you should get more points of like encourage. Moving around a lot and I want some logic to prevent.

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Windows swatting I had some people play the game and they would just like sit in a window where that I felt comfortable like gauging the the falling of the Apple side. Okay, if I like now release the Apple, then it's like, probably they will I hit this person, but I don't want this. You should move around a lot, so I thought about maybe having something else like opening and closing windows, and you can only use the windows that are open at the current point in time and not when they're closed.

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But this is all future and that's how I made a game in rest. It was quite hard. I ran into all the things that, like beginners, probably run into us like it right over something while it's mutable for like I found it. Your mute strings like every like everywhere would have reduced strings in a different language. I used numbers instead here or like integers, because it's like ah so hard I can't I can't figure it out, but it worked in the end and I'm with all the talks that I've listened to today.

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I'm like I, should really like to learn about traits and stuff, because it seems like exactly the thing that I need, but yeah, it's been a lot of fun and I can encourage you to do this yeah. Thank you.