This week we are going to learn to use Pygame, a collection of fun, powerful Python modules that manage graphics, animation, and even sound, making it easier for you to build sophis- ticated games. With Pygame handling tasks like drawing images to the screen, you can skip much of the tedious, difficult coding and focus on the higher-level logic of game dynamics.
Making games is an ideal way to have fun while learning a language. It’s deeply satisfying to watch others play a game you wrote, and writing a simple game will help you understand how professional games are written.
To learn about the pygame library we will be making an Alien invasion game on python somewhat like asteroids. Note the game will span a number of different files, so make a new folder called alien_invasion. Be sure to save all files for the game to this folder so import statements will work correctly.
Before we begin coding, we must install Pygame. Here’s how to do so on Linux, MacOS X, and Microsoft Windows:
To install on Windows you can go through this link.
To install on Mac you can go through this link.
To install Pygame using the package manager. Open a terminal window and run the following command, which will download and install Pygame onto your system:
sudo apt-get install python-pygame
If you are using pyhton 3 just replace python-pygame with python3-pygame.
To make sure its been installed correctly open the python interpreter by runnning python or python3 on the terminal depending on your version of python.
Then try running import pygame. If it runs without any error then pygame is successfully installed.
Now to begin building our game we will first make the pygame window where we will add the various elements of the game like ship and aliens, setup the background etc. You will learn how to create surfaces with pygame which refer to a part of the screen where you display a game element. Each element in the game is a surface. You will also learn about events which is an action that the user performs while playing the game, such as pressing a key or moving the mouse.
You can go through this notebook to learn about these things.
You can go through this video if you want to learn more about making surfaces in Pygame.
After building the basic setup, the next setup is to make the ship respond to user's inputs. In this section we will work on making the ship move according to input from the keyboard. Through this you will learn more about events. Another concept you will be introduced to is refactoring. Refactoring restructures the code so as to make it easier for you as well as other people to understand it as welss as develop it further. You can go through this notebook to learn about refactoring and piloting the ship.
To learn more about events in Pygame you can go through this and this video.
Next thing to do would be to give the ship the ability to shoot bullets. To do this you will learn about the concept of sprites. A sprite is a two dimensional image that is part of the larger graphical scene. Typically a sprite will be some kind of object in the scene that will be interacted with. You can learn about that in [this notebook].
Creating aliens is going to be quite similar to creating the ship. However, the difference is that while there was only a single ship, but there is a fleet of aliens. So we will be creating rows of aliens that will move sideways as well as downward. You can learn about this in [this notebook].
We have created the fleet of aliens. Now we will program those aliens to move in a specific pattern while heading down (just to make it a bit more interesting). We will also code the bullets to shoot down the aliens. In doing so you will learn about collisions. To detect collisions we just have to check whether 2 objects(sprites, rects...) overlap. Pygame makes this pretty easy to check. With this we will also code for ending our game. The game ends if any of the aliens hit the ship or reach the bottom. We will again use collision detetction for this. You can go through [this notebook] to see how we do all this.
To learn more about collisions you can go through this video.