Build a Simple SNAKE Game with Python! [PyGame Tutorial 2022]

what's going on you guys welcome back to the channel in today's video i'm gonna show you how to make the classic game snake in python using pygame [Music] all right i'm super excited to bring you guys this classic game tutorial snake is one of the first games it's super fun it's super addictive basically as you eat more food your body gets longer and it's a really great coding exercise and introduce introduction to a lot of python and object oriented concepts so if you do want the code and you don't want to follow along line for line there is a github repository the link is in the description of the video if you do grab the code and you're just here to peace out then be sure to leave a like on the video subscribe to the channel it helps me out a ton and i happy to bring all this content to you constantly all right so super excited to bring you this classic game tutorial i'm gonna do it all inside of python using pygame so if you've done any projects with pygame you know you need to start by importing pygame if you haven't installed it already you may need to run pip to install it and then two other modules we're going to use in this are the system module so import sys and then also the random module so import random and then whenever you are doing a pi game game it's a good idea after you import pygame to just do pygame dot in it right at the beginning to initialize it and uh i think let's just take a look at how we want to set up this overall game logic so there's really only two things going on in snake there's the snake's body moving throughout the grid and then there's the food that you're trying to track down so i think what we should do is we should just make two object classes one will be the snake itself your your character and then let's go ahead and just come down here and let's make the second one for food and you'll see why i'm doing it this way i think once we get into filling these out but basically initially i'm just gonna put pass in both of these and before we run anything we're going to come back but i want you to think of all the objects that need to go into the game right off the bat so basically we're going to have the snake we're going to have the food we're going to need a space to actually draw the grid so we'll call that define draw grid just like that and then beyond that so i'll do another pass right here beyond that we really just need a spot to store game variables so i'll call that a game variables library and this is where we'll put things like the screen width and the screen height so for this game because it's just a nice little game um it fits nicely in a 480 by 480 square but we'll put all of our game variables here as we define them and then really the last thing we have to do is just define our main game loop so this main game loop is something that i spend a lot of time setting up in in kind of every game and we'll try to go quickly now because we do it every single uh game so hopefully you've seen a few other tutorials but i'll try to explain as we go through it so you want to create a clock because that's going to control the speed at which your game runs so you just do pygame.time.clock and then you also want to define a screen by doing pygame dot display dot set mode and then you give it a few arguments so you give it as a tuple you your screen width and height um and then zero three two there we go and you define your screen and then if you're going to have a game where you want the potential for like a menu a few levels anything like that it's not bad idea to also define a surface and this is something that if you've made some simple games before you maybe have skipped this step and just drawn everything onto the screen but technically this is the best way to set your game up to have multiple screens throughout it multiple surfaces that you can draw things onto so to create one like we want for snake which is just going to take up the entire size of the screen that we just defined just use pygame dot surface with a capital s and then screen dot get size and then below that just add this surface equals and then surface dot convert okay and now let's move on so below that we're going to want to call the draw grid function all inside the main loop here so to do that you just call the uh you just call the function that you made for that uh sorry it's a little late in the evening over here and then since we're going to draw the grid onto the surface and not the screen i'm going to pass surface in here and then up in our draw grid function you're going to want to tell it right away that it's receiving a surface to be drawn onto so we'll we'll fill in the draw grid surface we'll fill in the draw grid function next but let's just finish defining the basics of our game loop here so we'll draw the surface and then the next thing we want to do is create an instance of both of our classes so we're going to have the snake and we're going to have food and i you can tell the instance of the class separate from the class itself by upper and lower case so the classes defined with a first letter caps is kind of the standard pythonic way of writing it and then your instance with lowercase is how you would tell that that's a specific instance okay so we define those and then we'll just say the score is equal to zero when the game boots up and now we put this while true and this is now the while loop that we're setting up where as long as the game has not been exited then we can keep playing and we can put all of our things that need to happen every loop of the game underneath this layer so we'll say clock.tick and here's where if you have like an action game like a platformer you might put an fps here like 60 for your frame rate but since this game is snake i'm actually going to use this clock to control how fast the snake moves throughout it so we're going to do clock.tick at 10. and then in here we'll be putting a lot of snake and food sub functions so like dot draw dot update receive player input so we'll put those things like here once we've fleshed them out underneath the class and then we'll again draw the grid on the surface and it's important actually to put these in both places because the first place that we did that we did this exact line of code is just doing it initially before the game boots up there we go so if you didn't have it here every time you boot up the game until uh kind of one or two seconds in one or two frames you might not even be able to detect it but technically the game would start up without a grid until it got to this point doing it here in the beginning is a really good way to make sure your screen loads in right away okay so then let's just go ahead and handle what we need to do um uh like update the screen and then close it so the last thing that you need to do is just pygame dot display dot update and then down here obviously you need to actually call that main so the main function that we made for the game you need to call it and let's go ahead now and actually fill in the drawing the grid function so go up to draw grid and uh we're going to use this a few for loops to make it procedurally generated it is going to be so much faster than if you were going to try to go in and draw every rectangle where it needed to be so what we'll do is we'll say for i in range zero and then what i think we should do is we should make some new functions that are going to tell us how large we want the grid to be not functions variables because we want this to be from zero to however many grid um grid rows there are and then for the x we want to be for from zero to however main grid columns there are so we need a few new variables here and to do that we're going to need what i will call grid size since we're going to make it a rectangle let's say that it's going to be a 20 by 20 grid and then we'll do grid width and grid height and i intentionally picked some sizes that are going to divide evenly here so grid width is going to be width divided by grid size and then height obviously is going to be height also divided by grid size and there are ways you could change this up so you could have like grid rows and grid columns if you didn't want to be a square but for our purposes square is going to be fine for everything so we'll say now draw the grid for y in range 0 up to and then make sure it's an integer just on the off chance because when you do division even if it's a whole number into a whole number python defaults by turning that value into a float so you did math and now instead of it just being 480 divided by 20 which is like 24 it's going to be 24.0 and we want it to be an integer so that we can iterate through the loop so that's why use the int in that place and then do integer of grid height and then underneath that do for x in range and then that'll be from 0 to in this time an integer of grid width okay and then a couple parentheses close it out and then what we want to do is actually make it a checkerboard pattern so you don't have to do this step you could just draw every rectangle the same color but checkerboard is going to look a lot better as you'll see once we get this drawn so what we'll say is if x plus y and now i'm going to use uh something you maybe don't see all the time if you're not super familiar with python and object-oriented programming this per it looks like the percentage sign it's actually the modulo operator i think is what it's called but it's basically division checking for remainder so what we're saying is if x plus y divided by 2 is an even division division so there's only two things that could be here right it could be an even or it could be an odd so it could be 0 2 4 6 8 or it could be 1 3 5 and 7. and the evens are when this remainder is going to be equal to 0 and we'll draw our rectangle which we'll call rect we're we're gonna draw that to be a slightly different color when it's when it's an even number than when it's an odd number and that's how we'll get our grid okay so uh we're gonna define the rectangle and uh i'm gonna do this again procedurally generated so that it works for every rectangle in the grid not really procedurally generated but generically enough that it'll work for every rectangle in the grid so we'll take our x and y integer which again are telling us what position in the grid they are and now we're defining an x and y start coordinate as well as a width and a height so we've got we want the x and y start coordinate and the way pi game draws objects is 0 0 would be at the top left corner and as you go to the right and down the screen you go farther out so 480 480 is the bottom right 0 0 is the top left so we'll do x times grid size and then y times grid size and that'll mean that however whatever integer you are in your rows and columns that's where your top left corner is going to be and then we need to give it a width and a height and what's easy about that is they are both the same since we made everything square it's just going to be grid size by grid size um and then so there's two steps to getting a rectangle actually on the screen there's defining the rectangle but then there's also pygame.drawrect and this is where this is where you could technically combine steps you could do pygame.draw.rect and then you could also define the rectangle in there but it's it's a little bit messier than just doing it this way and so we need to give it a color and i'm going to do colors in the same way that i do the rest of these game variables where rather than typing in rgb values for everything i'm going to define a color down here so if i want to modify colors later in the game i can just come right to one spot and i think that's going to be way easier so for grays if you're not sure and to do our checkerboard we'll do two shades of gray um for grays if you just basically make your r g and b values all the same you're going to get various shades of gray so that's what we'll do here and then we're going to take almost that exact same code that we used to draw that one and we will say else we don't even have to check math here and then we'll say rect is the same thing so it's the same rectangle but this time we're gonna make it rect two okay so we have our grid drawn we have the overall like boxes that the snake and the food are going to move around inside of so let's start actually defining the snake and the food but to start let's think about the snake and let's think about all the different things that the snake is able to do so with basically every class uh any class of any kind of complic like complicated functionality you're gonna want this def init um function and then you're gonna put a few things inside of this so you'll start uh you'll put like how long the snake is and then since snake the body gets longer as you eat more food you're going to want a list of all the positions that the snake occupies so you use this self.positions equals and then make a list and then initially so what we're doing right here is we're initializing the class so initially we're also going to put its position just starting in the middle of the screen um and then obviously as you move through the game and you eat more food that changes and updates but we're going to handle that in other functions and then the self.direction is going to be either up down left or right and so we will go ahead and make the handling for how you actually make all those movements in a second but to start let's say when the game boots up you're going to move in one direction let's just use the random module that we imported in the beginning to choose which one you want to do and we haven't defined these yet so let's go ahead and let's go down into our game variables and actually define what up down left and right are going to mean in the context of this game so i'm going to go ahead and make a variable for all four of these and it's kind of neat if you think about if you think about a grid and what we just talked about with how pi game draws objects onto the grid up down left and right can each be expressed in terms of a tuple or a set of two coordinates so for up your x isn't changing and your y is going up on the screen which is actually negative because 0 0 is at the very top 480 is at the very bottom so if you're going up you have zero negative one if you're going down you have zero positive one if you're going left then you have a change in the x direction but not in the y direction so minus one comma zero and then if you're going right it's the opposite you're going one and then no change in the y and the reason we're doing it this way is we're thinking about the map as a grid system and so this is telling how our coordinates on the grid need to change based on what direction we're going so this is a really cool intuitive way of setting up the movement and that's why when the the snake boots up right in the beginning we'll have it randomly go in one direction or another it won't really matter because you can't collide with one instance so you're not going to be at risk of hitting yourself right when the game starts okay and then let's go ahead and um use self.color so later in the in the um class definition when we draw the the snake onto the screen we'll have already given it a color let's come down into our library by the other colors and let's give it a nice green that's not like um too complicated let's just do r g b let's just do all the way green that's a little vibrant you may want to change this up pick your own colors that's totally up to you i just like green it's very typical so then let's use a little function to get the head position get head positions because we're going to need to check where the head is to be able to check oops i always type self in twice you're going to need to check where the head is to check if the head is colliding with the food um so this way all we'll do is we'll check where on the grid the head is and then we'll check the position of the food and if those two are the same then we'll know that it's time to grow the body of the snake by one regenerate a new piece of food and give you plus one for your score so we're going to need this function but all we need to do is return where in that positions list the first item is so self.positions zero okay now let's talk about um how to actually take a turn so to do this we'll define turn and we'll say self and then we're going to need to pass in another variable which we'll call point okay and so what we want to check is if self.length is greater than one so this is going to be as soon as you've eaten at least one point of food and then we'll check if the first coordinate of point because you got to think self um we're checking our x and y coordinate to be able to turn so we're checking it against a point which is going to also be an x and y coordinates so what we'll do is we'll check point at 0 times negative 1 which means that you're turning right because if you're going left then what you're doing is you're moving in the x direction and you're not moving in the y direction and if you want to turn to the right then you're flipping that you're going uh to multiply both the negative one and the zero by negative one um if you think back to how we define let me say that another way if you think back to how we define the four turns anytime a turn is taken you're able to multiply both of these by negative one because if you're up going down and you multiply zero by negative one then it's not going to change and then you multiply negative one by negative 1 and it will change so it's going to be this and then comma and then hopefully you see where it's going point 1 will be times negative 1. and what we do is we check to see if that is equal to self.direction and if it is then we can just return because we don't have to do anything we're already we're already going in that direction but else we'll set self.direction equal to the point that we passed in so that's how we'll check for turning and some of this stuff that i'm going through is going to make a lot more sense once we actually boot up the game and you can see it in action so for now just bear with me if you have any questions that aren't answered as we go through the tutorial feel free to ask them in the comments below and i will get back to you as soon as i can okay so next let's actually handle moving the snake so we'll say define move i always type self in twice when i'm doing tutorials and we'll say current is going to be equal to self.gethead position so that's going to tell us where the head is and then we'll create a variable uh x and y just coordinates and we'll set equal to self.direction so that's what's going to be up down left or right depending on the player's interaction with the arrow keys and so x and y will become variables that we can use in place of the 0 1 negative 1 of our movement directions and now what we'll say is our new location is going to be equal to and we're going to need a few sets of parentheses um and so the new location is going to be equal to the first character of current plus and then this is going to be equal to x times the grid size and then we're going to use again um so close that off close that off and then we're going to use again the remainder function the modulo divided by the overall width of the game and then that's going to be the first coordinate and then the second coordinate open new parentheses is going to be equal to current at the 1. so this is the second item inside of the coordinates and then it's going to be equal to that plus and then open the parentheses y times the grid size and then again we're gonna use the remainder operator okay and uh this hopefully now that it's typed out you can stand back and look at what each piece of this is actually doing but what it's basically saying is is okay whatever direction you're going it's either moving one square up one square down which is why we can use these direction coordinates the x and the y because if it's positive then what this is doing is adding one square to the right one square to the to the down direction if it's negative it's going to add one square to the left or one squared to the up and due to the four directions it'll never be doing both right one x or y is always going to be equal to zero and the other one is going to always be equal to either one or negative one so the only four things you can do in snake is move one square to the right one square to the left one square up and one square down and then all we have to do is move the rest of the body into the next spot that the piece in front of it took so that's what we'll do next i just hope that explanation was semi-clear i know it's coding is always a little bit easier to write than it is to explain i find but okay so what we'll do next is we'll check if the length of the positions um table of the list is greater than two and our new position is already in the self.positions library after the second place so this is checking from the second body part in the positions library all the way through to the end and if our new position is already in there then we're going to need to reset so we'll make an another function for that next but basically that means that we've just collided wherever we just commanded our body to go it hit a piece that already existed so that means we need to reset and that we basically lost the game or our snake body has to reset but we'll say else self oops self dot positions dot insert and then in place 0 we'll put the new coordinates and then if the length again of self.positions is greater than self dot length then what we're going to do is oh i put one two main parenthesis in there then what we'll do is we'll pop the last position off so self.positions and pop is just a list function that that always removes the last function from it and the reason we're doing it this way is because when we do hit ourselves and we reset we're gonna reset our length back to one and this will just allow us to remove all the positions that are on the body too long now um back so we get just the head so uh that'll probably make a little more sense now that we do this next one we'll just define the reset function um and we're going to so this is anytime the snake hits itself which resets the game we're gonna set the length back equal to one and now i'm going to grab the self. positions and self.direction that we put up here and just copy it down because this is what we're doing we're reinitializing the game so that you're back to a length of one your head is back to one technically you could reset the score to zero here again if you wanted i think it's okay if the score is just rolling and goes up up up until you have completed the game um until you're done playing so technically you get a high score just as long as you want to grind but your snake body will limit but you could totally put score in this reset as well okay but now let's go on to a really important one which is going to be drawing and for this one we're also going to want to pass in what surface we're drawing the snake onto and what we'll do is we'll say for pause which i'm going to just use as an abbreviation for positions and we'll say for pause in self dot positions we'll say that this time kind of like before when we drew the grid rect equals pie game dot capital r rect and make sure you get the cases right on these because pygame has some built-in stuff where you actually have to use case sensitive capital r's uh so we're defining a rectangle now which is going to say where um and what size we want the uh the snake body segments to look like and so we're doing this for every position in the positions table and we're going to say the x coordinate and the y coordinate are where we want it to draw on which is why we defined the grid in that way and then the size again we already have a variable for the x and the y coordinate of the sorry not the x y coordinate the length and the width for the snake's body and so then what we'll do is we'll say pygame.draw.rect and we'll put it on the surface and you could totally just do green right here but we actually um did something i think is a little bit better and we defined self.color a little earlier on and now we can just do rect and i think what you'll see you don't need this step if you don't want to but i'm going to draw the exact same rectangle on the screen except this time we're going to make it an outline so we'll make it black which will i don't think we've defined that yet so we'll have to make another one but what i'm going to do is i'm going to add this other condition which is a width so this is how you make a hollow rectangle you define a width for it and so we're just gonna make it width of one which will make it a real skinny line you could do width of two or three you can play along around with that one if you want but we'll say black is equal to zero zero zero so that we can continue using colors instead of directly defining the rgb variable values okay so surface black rectangle and that is everything we need for drawing all right and now i really did save the most important two functions for the end of this class here but the next one is handling keys so this is basically our event handling and what we're going to do is for event in pygame.event.get and this is uh pygame's built-in handler for tracking everything the player does every keystroke every movement of the mouse everything the system is doing is in pygame.event.get okay and so the first thing we need to do is what do we do if you want to quit the game so if the event.type equals pi game dot and then all caps quit uh and then all you have to do underneath that is pie game dot and then this time not caps quit with parentheses and then use that sys.exit as well to actually close the program okay and then that's the boring one that you have to put in every game because when you boot up by uh python if you don't put that in um the little red x in the corner isn't gonna do anything and you'll have an infinite while loop that never ends and then your game will crash immediately so the more exciting code for this game is if event dot type is equal to and then you want to check for this game everything we're doing is with pygame dot key down but there's also key up mouse button down mouse scroll wheel things like that so just keep that in mind but all we have to do here is check if the event dot key is equal to and we'll start with up so k underscore up and then if that's it then we'll take a turn where we go up okay so the nice thing is the way we defined the class is we don't have to do any complicated code in this event handling we can just call the correct sub function with the correct point all right so then we'll say else if it is down then we will take a turn down and you don't have to make these lifts technically if they were just ifs it would work but that that can get weird if you press multiple keys uh the nice thing about elifs is if you're pressing multiple keys it'll just look at whichever one completes the the if statement first and you don't have like overlapping code but really it's it's a cleaner more efficient way to write the code because never in snake are you able to turn two directions at once you have to do them as separate keystrokes no matter how close in time they are okay so that's really the entire event handling for the snake and we'll see where we call all of these sub functions down below once we define the food class and fortunately the real meat of this project was in the snake class the food class is a lot like what we just did but way simpler so just like before because it is a class you want this in itself right at the top and then for self dot position let's just put the first one at 0 0 and then self dot color we'll set this equal to red food uh red is kind of classic for um credits uh red is kind of a classic python uh snake color um i almost said python because that's what we're doing so we'll say r of two five five and then g and b of zero feel free to play around with the colors uh you don't have to follow this and actually right in the beginning when this thing's initialized we'll want to randomize the position so that position zero zero we obviously don't want that to be the actual starting position but we need to initialize the variable self.position which is why we did it there so first things first let's make a function called randomize position and what we'll do is we'll set self.position equal to and we're going to use the random module we imported random and we'll do that random integer and we'll have it go anywhere from zero which is all the way at the left of the screen through to grid width minus one because we don't want to be off the screen um and then we'll multiply it times grid size so that will make it uh actually its x starting coordinate and then we're going to do the exact same thing so i'm just going to copy it random.rand technically you don't even have to change it to grid height because it's a square but it's proper especially if you're going to play around the sizing later make this grid height minus one and then right at the beginning when you call self dot color and self.position also just call this function once so that it runs right in the beginning and places the first piece of food somewhere random okay so then uh let's create the draw and this is going to be a lot like the player draw because it's um or the snake draw because it is also just going to be a rectangle but this time we only have to draw one because the food is ever only occupying one grid location um so i'm just going to copy those three lines from the the snake draw function but we're going to modify it to be accurate for the snake or the food so what we want is self dot position at 0 and self.position at one rather than that intermediate pause variable the index or variable and then we still want to be grid size and grid size and we'll still use self.color and we'll still use an outline so you can see right away how the way we set up the class for the snake works really well for the class for the food okay so this is actually everything we have to do to define both classes now let's just go down in the main loop and make sure that we call the correct things inside of the main game okay so we already have the clock ticking let's go ahead and drop pygame dot in it in this loop actually you could put it right up here at the top that's totally fine um but let's put it inside of our main loop so that once it's called we initialize everything and let's see once we run it if that throws any flags i like it there a little bit more okay so after the surface we draw the grid and then let's go ahead and create our classes just like before score equals zero wall true clock equals tick all right and so the first thing we want to do is snake dot handle keys so every time through this we want to check if the players interacted with the game and do that first then we'll draw and then we'll actually move the snake's body based on whatever current direction it's going and here's where we should check if it has eaten the food so that's if snake dot get head position is equal to food position and if that's true then we want the snake dot length to be one longer than it just was we want our score to be one greater than it just was and we want to run the randomized position function for our food again so it's going to give us a new randomly located food position and then we want to draw the snake again because now it could be longer if it actually ate the food and then we want to draw the food again wherever it got located to and then uh let's see we want to screen dot blit so if you're going to do what i talked about right at the beginning and you're going to create a surface separate from the screen you need to make sure that you actually draw your surface onto the screen otherwise this game is never going to get displayed anywhere so to do that you do screen dot blit and then what you want to blit or block transfer you're just saying what data you want to push onto the screen and in this case we want to be everything that's on our surface and the coordinate we want to be on is zero zero the only reason you would not put it at zero zero is if this was like a pop-up or a partial screen or a sub screen inside a larger screen so we'll put it zero zero and then let's put text on the screen that's going to tell us what the current score is so to do that we'll do text equals font dot render and then we're gonna do it this way we'll say score of and we'll say just zero initially but by putting it in that curly brackets we can come here afterwards and do dot format and then tell it what variable to put in that formatted curly brackets and we'll say score true and then black and then what we have to do you see we're getting the red underline in um under font is we actually have to come up and define a font so underneath our up down left right let's say font equals pie game dot font with a lower case and then font with the caps and we'll say so i like to use free sans bold in my games just because it's built in to any computer running windows and make it a size 30 so that's just a good font size you can make it smaller if you find that's kind of disruptive to the game and actually since we're doing that outside of the game loop we are going to want to put pygame dot in it here as well because uh if you try to run it you called a font here you need to have initialized pi game by then so now you can see we're not getting the red underline anymore which is good and then just like we did with the surface we also have to blit the text onto the screen and i'll just put it 510 so it's a little bit to the right and a little bit down and this should be everything we have to do as you can see like there's really not that much to put in the main game loop if you set up your classes so that they take care of most of the complicated functionality and if you go back through this so we'll run it in just a second but if you go back through this and you look at each subsection of code you'll see at no point is there a really complicated operation it's a lot of really simple operations that when combined give you cool functionality that is the essence that is the benefit and the bread and butter of object oriented programming so knock on wood let's see how close we got and what kind of troubleshooting we have to do okay so right away it moved to the left without me pressing anything and if you boot this up a few times you should see it going in different directions to start i hit the food my body grows by one the score gets bigger i can move in all four directions if you find it's too slow or too fast for your liking try changing the speed at which that pie game dot time ticks at so for example if you were to go from 10 up to 20 you would find the game extremely difficult it would move so fast but like 12 and 15 are just uh slightly more challenging because what that clock dot tick is doing is saying the number of times to run through the loop per second so basically 10 is saying it'll only move 10 squares per second if you bring that up to 20 it'll move 20 squares per second and since our grid is 24 by 24 you that's going to be clear across the entire board okay and so here you can see it's really cool it can move off the screen to one side uh and i hit myself there because i got longer than the board we kept this score going so that was one thing i talked about different games of snake are kind of they operate in different ways some of them reset the score every time you die some of them it's just as long as you want to play in one sitting that's your score but your snake body resets every time and honestly no one's competitively playing snake they're playing for fun so make it your own this is really a great exercise to learn the basics of python and pygame i think it's a really great beginner tutorial if you did find this enjoyable be sure to check out the channel we have a ton of game tutorials ranging from other basic ones like pong all the way up to pretty complicated ones like entire apps like idle clicker apps we did a space invaders tutorial and a lot of other things that range from super basic to intermediate don't really do too many advanced things because the advanced people typically know what they're doing but i hope you enjoyed this video if you do have any questions or ideas for what you'd like to see in the future be sure to let me know about in the comments below as always i really appreciate the support and if you'd be willing to leave a like on the video subscribe to the channel it helps me out a ton and as always good luck with your code and thanks for watching thanks bye