Pong in Python! Part 3 - Collision Detection, Game Over and Restarting

what's going on you guys welcome back to the channel and today we've got kind of a fun one for you we're going to learn to build the classic game pong the game that pretty much started modern video games we're going to learn to recreate that in python using pygame i haven't put in the code yet to handle like bouncing off of the paddle and bouncing off of your paddle but you can tell like your computerized opponent is going to be tracking it pretty good so let's actually do that next that's going to be um kind of the bulk of how pong is played right it's actually the ball bounces off the paddles and um look when they made uh pong back in the day they didn't have anything pre-built pie game kind of has the benefit of um having a module to delet detect collision between different objects um so what we're gonna do is in the event handler uh next kind of in that same area we're going to check for collision so let's get into that and let's go ahead and create another you could probably use this update ball um function to do the same thing but that function has already got a lot going on so i think it would be wise to uh i think it'd be wise to do a check collision um separate and we'll we'll make two check collision player and we'll do check collision ai and these are going to look pretty similar but for the sake of not having to pass in like 10 000 parameters per um not having to pass in 10 000 parameters per uh function i think separating mount makes more sense so we will do this we will say player i think we can just do player and we might be able to just do ball and then we will need ball x direction and i think all we want if there is collision is we want to flip the ball x direction so we can just call x direction so i think we can do it this way where we pass in the ball we pass in the computer here and then we pass in the ball x direction but let's go ahead and write the function and i'm sure while we're writing the function that will probably uh direction right in the function that'll tell us if we missed something it always does okay and we called this check collision with player just check collision player okay and the order of the variables let's go ahead and just steal these to be accurate and we are returning ball x direction so what i'm going to do is if and then this is a built in pie game function it is if ball dot collide and then with player okay and then all i'm gonna do is say ball x direction and then times negative one uh i think that that is all we have to do to handle bouncing off the paddle because this collide rect is checking um is checking the rectangle of the object that you called and then it's also checking the rectangle of the object that you put inside of the parentheses so really if it hits the player or it hits the computer we just want it to go the opposite direction so that might do it i called it check collision ai yeah that's hardcore i haven't changed this name yet okay so let's go ahead and run this see if it bounces off the paddles okay so we do return ball x direction but it hits the right paddle and it just keeps bouncing into it let's see i don't know if this will fix it or not but let's try combining these let's say check collisions ball player ai uh computer stupid and let's go ahead and tweak our function to be check collisions pretty sure this isn't going to be it but gotta troubleshoot okay so let's just say if it collides with the player that we want the direction to be equal to one and then l if the ball collides with the computer then we want the x direction to be equal to negative one bounce back to the left and that will do it all right not super confident that that's going to fix it and apparently it did wow all right so um look we made it guys you can you can bounce off of the paddles you can um you can play against the computer like i said you could set up the exact same controls for s and w uh for like up and down arrow and then they could control the right guy if you want to but right now this is the basics of pong working and now i'm just going to kind of add a few more things that i think make the game a little bit more fun but right here you just created you know the essence of pong so what i want to do next before patting myself on the back too much i want to get rid of the fact that it can just bounce off the left and right walls i want to make that game over so i'm going to start that process by creating a variable that i will call game over and it's going to be equal to false right when the game starts and we're going to create a new function that will call once per game loop and i'm going to call it check game over okay and we're going to get the game over variable back from there so game over is going to be equal to check game over and what we're going to do is all we're going to pass in is ball x we don't need anything else because all we're going to do is check if the game has gotten all the way to the left or not and then let's go to where the ball updates right um what do that is update ball this function and we'll say if game over is false or if not game over okay so um that should make sense um now we're saying the ball is only going to update if game over is not true and let's go ahead and take care of the code that's actually going to enter a game over scenario so we called that function check game over and we're passing in ball x and i think we need to pass in game over as well actually because the current status of that is going to make a big difference all right and what we will say is if ball x is equal to zero which is when it hits the left wall or and actually let's say less than or equal to because if it's jumping around by multiple pixels uh it's just better to catch it this way so if it's less than or equal to 0 or ball x is greater than or equal to 290 because it's 10 pixels wide so that's when it hits the right wall we will say game over is equal to true and let's go ahead and add another condition here and say and game over is equal to false there's no reason to run this code if uh game over is true so then we will return game over and i think that will handle that so let's go ahead and see i'm gonna let it hit the left wall here real quick and you can see the ball stops moving let's go ahead and add it to the ai too because the computer gets a little confused um so let's move this guy back in there and i'm okay with being able to move the player while game's over it's not going to get you any bonus points it's not going to do anything for you um but the yeah so there we go the computer should stop moving the ball should stop moving nothing should happen so that's good let's go ahead and put in some restart logic because obviously this hopefully is a game that you enjoy playing you're not going to play just once so uh let's handle that and let's make a uh let's make another if statement and say what we want to do if game over is true and we're going to create some text now that i will say is game over text and actually something that we didn't do at the beginning of this game that i try to do at the beginning of every game is i just try to define a font um because any text that you want to draw onto the screen in the game you have to use pygame's very specific method of putting text on the screen so that starts by defining a variable i call font or off net apparently because i can't type fortunately typing is not a requirement for coding okay so font equals pie game dot font dot font and then uh you can use any font you want a lot of times using a fun font can really change like the theme of your game i am using a free one that comes built in with python okay and then font size is the second uh is the second variable i'll just say 20. that's kind of normal game font but you can play around as much as you want but okay so we defined font as a variable and now in our game over text we're gonna you have to do it in two steps you have to render it and then you have to draw it onto the screen with the blip function so game over text is going to be equal to font dot render and then game over so we're telling them they lost and second variable true we're gonna make it white on a black background okay and uh let's see the second piece that i was talking about is screen dot blit you have to draw the text onto the screen so what are we drawing game over text and then you give it coordinates for where to draw it onto so i'm going to do 8130 that's kind of high in the middle of the screen and again that's just something you can play around with but let's see how that looks game over okay you