This code snippet stores and updates a list of high scores for a video game:

Question

After creating a game, it would be nice to save our best scores. If we only save the score in memory it will be gone the next time we play. Instead, we can save the scores in the browser’s local storage.

This article steps through how to save high scores in local storage and then how to present them on the screen for the player. If you want to read about the games that inspired this article…

When I started learning computer programming late in the last millennium, it was driven by my desire to write computer games. I tried to figure out how to write games in every language and on every platform I learned, including Python. That’s how I discovered

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 and learned how to use it to write games and other graphical programs. At the time, I really wanted a primer on

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7.

By the end of this article, you’ll be able to:

Draw items on your screen
Play sound effects and music
Handle user input
Implement event loops
Describe how game programming differs from standard procedural Python programming

This primer assumes you have a basic understanding of writing Python programs, including user-defined functions, imports, loops, and conditionals. You should also be familiar with how to open files on your platform. A basic understanding of object-oriented Python is helpful as well.

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 works with most versions of Python, but Python 3.6 is recommended and used throughout this article.

You can get all of the code in this article to follow along:

Sample Code: Click here to download the source code for the PyGame sample project used in this tutorial.

Background and Setup

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 is a Python wrapper for the SDL library, which stands for Simple DirectMedia Layer. SDL provides cross-platform access to your system’s underlying multimedia hardware components, such as sound, video, mouse, keyboard, and joystick.

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 started life as a replacement for the stalled PySDL project. The cross-platform nature of both SDL and

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 means you can write games and rich multimedia Python programs for every platform that supports them!

To install

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 on your platform, use the appropriate

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()
18
19# Define constants for the screen width and height
20SCREEN_WIDTH = 800
21SCREEN_HEIGHT = 600
22
23# Create the screen object
24# The size is determined by the constant SCREEN_WIDTH and SCREEN_HEIGHT
25screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))

4 command:

$ pip install pygame

You can verify the install by loading one of the examples that comes with the library:

$ python3 -m pygame.examples.aliens

If a game window appears, then

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 is installed properly! If you run into problems, then the Getting Started guide outlines some known issues and caveats for all platforms.

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Basic PyGame Program

Before getting down to specifics, let’s take a look at a basic

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 program. This program creates a window, fills the background with white, and draws a blue circle in the middle of it:

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

When you run this program, you’ll see a window that looks like this:

Let’s break this code down, section by section:

Lines 4 and 5 import and initialize the

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 library. Without these lines, there is no

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7.

Line 8 sets up your program’s display window. You provide either a list or a tuple that specifies the width and height of the window to create. This program uses a list to create a square window with 500 pixels on each side.
Lines 11 and 12 set up a game loop to control when the program ends. You’ll cover game loops later on in this tutorial.

Lines 15 to 17 scan and handle events within the game loop. You’ll get to events a bit later as well. In this case, the only event handled is

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()
18
19# Define constants for the screen width and height
20SCREEN_WIDTH = 800
21SCREEN_HEIGHT = 600
22
23# Create the screen object
24# The size is determined by the constant SCREEN_WIDTH and SCREEN_HEIGHT
25screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))

9, which occurs when the user clicks the window close button.

Line 20 fills the window with a solid color.

27# Variable to keep the main loop running
28running = True
29
30# Main loop
31while running:
32    # Look at every event in the queue
33    for event in pygame.event.get():
34        # Did the user hit a key?
35        if event.type == KEYDOWN:
36            # Was it the Escape key? If so, stop the loop.
37            if event.key == K_ESCAPE:
38                running = False
39
40        # Did the user click the window close button? If so, stop the loop.
41        elif event.type == QUIT:
42            running = False

0 accepts either a list or tuple specifying the RGB values for the color. Since

27# Variable to keep the main loop running
28running = True
29
30# Main loop
31while running:
32    # Look at every event in the queue
33    for event in pygame.event.get():
34        # Did the user hit a key?
35        if event.type == KEYDOWN:
36            # Was it the Escape key? If so, stop the loop.
37            if event.key == K_ESCAPE:
38                running = False
39
40        # Did the user click the window close button? If so, stop the loop.
41        elif event.type == QUIT:
42            running = False

1 was provided, the window is filled with white.

Line 23 draws a circle in the window, using the following parameters:

27# Variable to keep the main loop running
28running = True
29
30# Main loop
31while running:
32    # Look at every event in the queue
33    for event in pygame.event.get():
34        # Did the user hit a key?
35        if event.type == KEYDOWN:
36            # Was it the Escape key? If so, stop the loop.
37            if event.key == K_ESCAPE:
38                running = False
39
40        # Did the user click the window close button? If so, stop the loop.
41        elif event.type == QUIT:
42            running = False

2: the window on which to draw

27# Variable to keep the main loop running
28running = True
29
30# Main loop
31while running:
32    # Look at every event in the queue
33    for event in pygame.event.get():
34        # Did the user hit a key?
35        if event.type == KEYDOWN:
36            # Was it the Escape key? If so, stop the loop.
37            if event.key == K_ESCAPE:
38                running = False
39
40        # Did the user click the window close button? If so, stop the loop.
41        elif event.type == QUIT:
42            running = False

3: a tuple containing RGB color values

27# Variable to keep the main loop running
28running = True
29
30# Main loop
31while running:
32    # Look at every event in the queue
33    for event in pygame.event.get():
34        # Did the user hit a key?
35        if event.type == KEYDOWN:
36            # Was it the Escape key? If so, stop the loop.
37            if event.key == K_ESCAPE:
38                running = False
39
40        # Did the user click the window close button? If so, stop the loop.
41        elif event.type == QUIT:
42            running = False

4: a tuple specifying the center coordinates of the circle

27# Variable to keep the main loop running
28running = True
29
30# Main loop
31while running:
32    # Look at every event in the queue
33    for event in pygame.event.get():
34        # Did the user hit a key?
35        if event.type == KEYDOWN:
36            # Was it the Escape key? If so, stop the loop.
37            if event.key == K_ESCAPE:
38                running = False
39
40        # Did the user click the window close button? If so, stop the loop.
41        elif event.type == QUIT:
42            running = False

5: the radius of the circle to draw in pixels

Line 26 updates the contents of the display to the screen. Without this call, nothing appears in the window!

Line 29 exits

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7. This only happens once the loop finishes.

That’s the

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 version of “Hello, World.” Now let’s dig a little deeper into the concepts behind this code.

PyGame Concepts

As

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 and the SDL library are portable across different platforms and devices, they both need to define and work with abstractions for various hardware realities. Understanding those concepts and abstractions will help you design and develop your own games.

Initialization and Modules

The

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 library is composed of a number of Python constructs, which include several different modules. These modules provide abstract access to specific hardware on your system, as well as uniform methods to work with that hardware. For example,

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

0 allows uniform access to your video display, while

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

1 allows abstract control of your joystick.

After importing the

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 library in the example above, the first thing you did was initialize PyGame using

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

3. This function calls the separate

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

4 functions of all the included

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 modules. Since these modules are abstractions for specific hardware, this initialization step is required so that you can work with the same code on Linux, Windows, and Mac.

Displays and Surfaces

In addition to the modules,

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 also includes several Python classes, which encapsulate non-hardware dependent concepts. One of these is the

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 which, at its most basic, defines a rectangular area on which you can draw.

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 objects are used in many contexts in

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7. Later you’ll see how to load an image into a

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 and display it on the screen.

In

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7, everything is viewed on a single user-created

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

0, which can be a window or a full screen. The display is created using

54# This line says "Draw surf onto the screen at the center"
55screen.blit(surf, (SCREEN_WIDTH/2, SCREEN_HEIGHT/2))
56pygame.display.flip()

3, which returns a

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 representing the visible part of the window. It is this

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 that you pass into drawing functions like

54# This line says "Draw surf onto the screen at the center"
55screen.blit(surf, (SCREEN_WIDTH/2, SCREEN_HEIGHT/2))
56pygame.display.flip()

6, and the contents of that

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 are pushed to the display when you call

54# This line says "Draw surf onto the screen at the center"
55screen.blit(surf, (SCREEN_WIDTH/2, SCREEN_HEIGHT/2))
56pygame.display.flip()

8.

Images and Rects

Your basic

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 program drew a shape directly onto the display’s

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7, but you can also work with images on the disk. The

54# Put the center of surf at the center of the display
55surf_center = (
56    (SCREEN_WIDTH-surf.get_width())/2,
57    (SCREEN_HEIGHT-surf.get_height())/2
58)
59
60# Draw surf at the new coordinates
61screen.blit(surf, surf_center)
62pygame.display.flip()

1 module allows you to load and save images in a variety of popular formats. Images are loaded into

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 objects, which can then be manipulated and displayed in numerous ways.

As mentioned above,

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 objects are represented by rectangles, as are many other objects in

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7, such as images and windows. Rectangles are so heavily used that there is a special

54# Put the center of surf at the center of the display
55surf_center = (
56    (SCREEN_WIDTH-surf.get_width())/2,
57    (SCREEN_HEIGHT-surf.get_height())/2
58)
59
60# Draw surf at the new coordinates
61screen.blit(surf, surf_center)
62pygame.display.flip()

5 class just to handle them. You’ll be using

54# Put the center of surf at the center of the display
55surf_center = (
56    (SCREEN_WIDTH-surf.get_width())/2,
57    (SCREEN_HEIGHT-surf.get_height())/2
58)
59
60# Draw surf at the new coordinates
61screen.blit(surf, surf_center)
62pygame.display.flip()

5 objects and images in your game to draw players and enemies, and to manage collisions between them.

Okay, that’s enough theory. Let’s design and write a game!

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Basic Game Design

Before you start writing any code, it’s always a good idea to have some design in place. Since this is a tutorial game, let’s design some basic gameplay for it as well:

The goal of the game is to avoid incoming obstacles:
- The player starts on the left side of the screen.
- The obstacles enter randomly from the right and move left in a straight line.
The player can move left, right, up, or down to avoid the obstacles.
The player cannot move off the screen.
The game ends either when the player is hit by an obstacle or when the user closes the window.

When he was describing software projects, a former colleague of mine used to say, “You don’t know what you do until you know what you don’t do.” With that in mind, here are some things that won’t be covered in this tutorial:

No multiple lives
No scorekeeping
No player attack capabilities
No advancing levels
No boss characters

You’re free to try your hand at adding these and other features to your own program.

Let’s get started!

Importing and Initializing PyGame

After you import

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7, you’ll also need to initialize it. This allows

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 to connect its abstractions to your specific hardware:

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

The

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 library defines many things besides modules and classes. It also defines some local constants for things like keystrokes, mouse movements, and display attributes. You reference these constants using the syntax

20# Define a Player object by extending pygame.sprite.Sprite
21# The surface drawn on the screen is now an attribute of 'player'
22class Player(pygame.sprite.Sprite):
23    def __init__(self):
24        super(Player, self).__init__()
25        self.surf = pygame.Surface((75, 25))
26        self.surf.fill((255, 255, 255))
27        self.rect = self.surf.get_rect()

0. By importing specific constants from

20# Define a Player object by extending pygame.sprite.Sprite
21# The surface drawn on the screen is now an attribute of 'player'
22class Player(pygame.sprite.Sprite):
23    def __init__(self):
24        super(Player, self).__init__()
25        self.surf = pygame.Surface((75, 25))
26        self.surf.fill((255, 255, 255))
27        self.rect = self.surf.get_rect()

1, you can use the syntax

20# Define a Player object by extending pygame.sprite.Sprite
21# The surface drawn on the screen is now an attribute of 'player'
22class Player(pygame.sprite.Sprite):
23    def __init__(self):
24        super(Player, self).__init__()
25        self.surf = pygame.Surface((75, 25))
26        self.surf.fill((255, 255, 255))
27        self.rect = self.surf.get_rect()

2 instead. This will save you some keystrokes and improve overall readability.

Setting Up the Display

Now you need something to draw on! Create a screen to be the overall canvas:

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()
18
19# Define constants for the screen width and height
20SCREEN_WIDTH = 800
21SCREEN_HEIGHT = 600
22
23# Create the screen object
24# The size is determined by the constant SCREEN_WIDTH and SCREEN_HEIGHT
25screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))

You create the screen to use by calling

20# Define a Player object by extending pygame.sprite.Sprite
21# The surface drawn on the screen is now an attribute of 'player'
22class Player(pygame.sprite.Sprite):
23    def __init__(self):
24        super(Player, self).__init__()
25        self.surf = pygame.Surface((75, 25))
26        self.surf.fill((255, 255, 255))
27        self.rect = self.surf.get_rect()

3 and passing a tuple or list with the desired width and height. In this case, the window is 800x600, as defined by the constants

20# Define a Player object by extending pygame.sprite.Sprite
21# The surface drawn on the screen is now an attribute of 'player'
22class Player(pygame.sprite.Sprite):
23    def __init__(self):
24        super(Player, self).__init__()
25        self.surf = pygame.Surface((75, 25))
26        self.surf.fill((255, 255, 255))
27        self.rect = self.surf.get_rect()

4 and

20# Define a Player object by extending pygame.sprite.Sprite
21# The surface drawn on the screen is now an attribute of 'player'
22class Player(pygame.sprite.Sprite):
23    def __init__(self):
24        super(Player, self).__init__()
25        self.surf = pygame.Surface((75, 25))
26        self.surf.fill((255, 255, 255))
27        self.rect = self.surf.get_rect()

5 on lines 20 and 21. This returns a

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 which represents the inside dimensions of the window. This is the portion of the window you can control, while the OS controls the window borders and title bar.

If you run this program now, then you’ll see a window pop up briefly and then immediately disappear as the program exits. Don’t blink or you might miss it! In the next section, you’ll focus on the main game loop to ensure that your program exits only when given the correct input.

Setting Up the Game Loop

Every game from Pong to Fortnite uses a game loop to control gameplay. The game loop does four very important things:

Processes user input
Updates the state of all game objects
Updates the display and audio output
Maintains the speed of the game

Every cycle of the game loop is called a frame, and the quicker you can do things each cycle, the faster your game will run. Frames continue to occur until some condition to exit the game is met. In your design, there are two conditions that can end the game loop:

The player collides with an obstacle. (You’ll cover collision detection later.)
The player closes the window.

The first thing the game loop does is process user input to allow the player to move around the screen. Therefore, you need some way to capture and process a variety of input. You do this using the

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 event system.

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Processing Events

Key presses, mouse movements, and even joystick movements are some of the ways in which a user can provide input. All user input results in an event being generated. Events can happen at any time and often (but not always) originate outside the program. All events in

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 are placed in the event queue, which can then be accessed and manipulated. Dealing with events is referred to as handling them, and the code to do so is called an event handler.

Every event in

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 has an event type associated with it. For your game, the event types you’ll focus on are keypresses and window closure. Keypress events have the event type

$ python3 -m pygame.examples.aliens

00, and the window closure event has the type

$ python3 -m pygame.examples.aliens

01. Different event types may also have other data associated with them. For example, the

$ python3 -m pygame.examples.aliens

00 event type also has a variable called

$ python3 -m pygame.examples.aliens

03 to indicate which key was pressed.

You access the list of all active events in the queue by calling

$ python3 -m pygame.examples.aliens

04. You then loop through this list, inspect each event type, and respond accordingly:

27# Variable to keep the main loop running
28running = True
29
30# Main loop
31while running:
32    # Look at every event in the queue
33    for event in pygame.event.get():
34        # Did the user hit a key?
35        if event.type == KEYDOWN:
36            # Was it the Escape key? If so, stop the loop.
37            if event.key == K_ESCAPE:
38                running = False
39
40        # Did the user click the window close button? If so, stop the loop.
41        elif event.type == QUIT:
42            running = False

Let’s take a closer look at this game loop:

Line 28 sets up a control variable for the game loop. To exit the loop and the game, you set
```
$ python3 -m pygame.examples.aliens
```
05. The game loop starts on line 29.
Line 31 starts the event handler, walking through every event currently in the event queue. If there are no events, then the list is empty, and the handler won’t do anything.
Lines 35 to 38 check if the current
```
$ python3 -m pygame.examples.aliens
```
06 is a
```
$ python3 -m pygame.examples.aliens
```
00 event. If it is, then the program checks which key was pressed by looking at the
```
$ python3 -m pygame.examples.aliens
```
08 attribute. If the key is the Esc key, indicated by
```
$ python3 -m pygame.examples.aliens
```
09, then it exits the game loop by setting
```
$ python3 -m pygame.examples.aliens
```
05.
Lines 41 and 42 do a similar check for the event type called
```
$ python3 -m pygame.examples.aliens
```
01. This event only occurs when the user clicks the window close button. The user may also use any other operating system action to close the window.

When you add these lines to the previous code and run it, you’ll see a window with a blank or black screen:

The window won’t disappear until you press the Esc key, or otherwise trigger a

$ python3 -m pygame.examples.aliens

01 event by closing the window.

Drawing on the Screen

In the sample program, you drew on the screen using two commands:

27# Variable to keep the main loop running
28running = True
29
30# Main loop
31while running:
32    # Look at every event in the queue
33    for event in pygame.event.get():
34        # Did the user hit a key?
35        if event.type == KEYDOWN:
36            # Was it the Escape key? If so, stop the loop.
37            if event.key == K_ESCAPE:
38                running = False
39
40        # Did the user click the window close button? If so, stop the loop.
41        elif event.type == QUIT:
42            running = False

0 to fill the background

54# This line says "Draw surf onto the screen at the center"
55screen.blit(surf, (SCREEN_WIDTH/2, SCREEN_HEIGHT/2))
56pygame.display.flip()

6 to draw a circle

Now you’ll learn about a third way to draw to the screen: using a

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7.

Recall that a

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 is a rectangular object on which you can draw, like a blank sheet of paper. The

27# Variable to keep the main loop running
28running = True
29
30# Main loop
31while running:
32    # Look at every event in the queue
33    for event in pygame.event.get():
34        # Did the user hit a key?
35        if event.type == KEYDOWN:
36            # Was it the Escape key? If so, stop the loop.
37            if event.key == K_ESCAPE:
38                running = False
39
40        # Did the user click the window close button? If so, stop the loop.
41        elif event.type == QUIT:
42            running = False

2 object is a

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7, and you can create your own

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 objects separate from the display screen. Let’s see how that works:

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

After the screen is filled with white on line 45, a new

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 is created on line 48. This

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 is 50 pixels wide, 50 pixels tall, and assigned to

$ python3 -m pygame.examples.aliens

22. At this point, you treat it just like the

27# Variable to keep the main loop running
28running = True
29
30# Main loop
31while running:
32    # Look at every event in the queue
33    for event in pygame.event.get():
34        # Did the user hit a key?
35        if event.type == KEYDOWN:
36            # Was it the Escape key? If so, stop the loop.
37            if event.key == K_ESCAPE:
38                running = False
39
40        # Did the user click the window close button? If so, stop the loop.
41        elif event.type == QUIT:
42            running = False

2. So on line, 51 you fill it with black. You can also access its underlying

54# Put the center of surf at the center of the display
55surf_center = (
56    (SCREEN_WIDTH-surf.get_width())/2,
57    (SCREEN_HEIGHT-surf.get_height())/2
58)
59
60# Draw surf at the new coordinates
61screen.blit(surf, surf_center)
62pygame.display.flip()

5 using

$ python3 -m pygame.examples.aliens

25. This is stored as

$ python3 -m pygame.examples.aliens

26 for later use.

Using $ python3 -m pygame.examples.aliens 27 and $ python3 -m pygame.examples.aliens 28

Just creating a new

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 isn’t enough to see it on the screen. To do that, you need to blit the

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 onto another

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7. The term

$ python3 -m pygame.examples.aliens

32 stands for Block Transfer, and

$ python3 -m pygame.examples.aliens

27 is how you copy the contents of one

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 to another. You can only

$ python3 -m pygame.examples.aliens

27 from one

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 to another, but since the screen is just another

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7, that’s not a problem. Here’s how you draw

$ python3 -m pygame.examples.aliens

22 on the screen:

54# This line says "Draw surf onto the screen at the center"
55screen.blit(surf, (SCREEN_WIDTH/2, SCREEN_HEIGHT/2))
56pygame.display.flip()

The

$ python3 -m pygame.examples.aliens

27 call on line 55 takes two arguments:

The

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 to draw

The location at which to draw it on the source

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7

The coordinates

$ python3 -m pygame.examples.aliens

42 tell your program to place

$ python3 -m pygame.examples.aliens

22 in the exact center of the screen, but it doesn’t quite look that way:

The reason why the image looks off-center is that

$ python3 -m pygame.examples.aliens

27 puts the top-left corner of

$ python3 -m pygame.examples.aliens

22 at the location given. If you want

$ python3 -m pygame.examples.aliens

22 to be centered, then you’ll have to do some math to shift it up and to the left. You can do this by subtracting the width and height of

$ python3 -m pygame.examples.aliens

22 from the width and height of the screen, dividing each by 2 to locate the center, and then passing those numbers as arguments to

$ python3 -m pygame.examples.aliens

48:

54# Put the center of surf at the center of the display
55surf_center = (
56    (SCREEN_WIDTH-surf.get_width())/2,
57    (SCREEN_HEIGHT-surf.get_height())/2
58)
59
60# Draw surf at the new coordinates
61screen.blit(surf, surf_center)
62pygame.display.flip()

Notice the call to

54# This line says "Draw surf onto the screen at the center"
55screen.blit(surf, (SCREEN_WIDTH/2, SCREEN_HEIGHT/2))
56pygame.display.flip()

8 after the call to

$ python3 -m pygame.examples.aliens

50. This updates the entire screen with everything that’s been drawn since the last flip. Without the call to

$ python3 -m pygame.examples.aliens

28, nothing is shown.

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Sprites

In your game design, the player starts on the left, and obstacles come in from the right. You can represent all the obstacles with

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 objects to make drawing everything easier, but how do you know where to draw them? How do you know if an obstacle has collided with the player? What happens when the obstacle flies off the screen? What if you want to draw background images that also move? What if you want your images to be animated? You can handle all these situations and more with sprites.

In programming terms, a sprite is a 2D representation of something on the screen. Essentially, it’s a picture.

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 provides a

$ python3 -m pygame.examples.aliens

54 class, which is designed to hold one or several graphical representations of any game object that you want to display on the screen. To use it, you create a new class that extends

$ python3 -m pygame.examples.aliens

54. This allows you to use its built-in methods.

Players

Here’s how you use

$ python3 -m pygame.examples.aliens

54 objects with the current game to define the player. Insert this code after line 18:

20# Define a Player object by extending pygame.sprite.Sprite
21# The surface drawn on the screen is now an attribute of 'player'
22class Player(pygame.sprite.Sprite):
23    def __init__(self):
24        super(Player, self).__init__()
25        self.surf = pygame.Surface((75, 25))
26        self.surf.fill((255, 255, 255))
27        self.rect = self.surf.get_rect()

You first define

$ python3 -m pygame.examples.aliens

57 by extending

$ python3 -m pygame.examples.aliens

58 on line 22. Then

$ python3 -m pygame.examples.aliens

59 uses

$ python3 -m pygame.examples.aliens

60 to call the

$ python3 -m pygame.examples.aliens

59 method of

$ python3 -m pygame.examples.aliens

54. For more info on why this is necessary, you can read Supercharge Your Classes With Python super().

Next, you define and initialize

$ python3 -m pygame.examples.aliens

63 to hold the image to display, which is currently a white box. You also define and initialize

$ python3 -m pygame.examples.aliens

64, which you’ll use to draw the player later. To use this new class, you need to create a new object and change the drawing code as well. Expand the code block below to see it all together:

Expand for full codeShow/Hide

$ python3 -m pygame.examples.aliens

0

Run this code. You’ll see a white rectangle at roughly the middle of the screen:

What do you think would happen if you changed line 59 to

$ python3 -m pygame.examples.aliens

65? Try it and see:

$ python3 -m pygame.examples.aliens

1

When you pass a

54# Put the center of surf at the center of the display
55surf_center = (
56    (SCREEN_WIDTH-surf.get_width())/2,
57    (SCREEN_HEIGHT-surf.get_height())/2
58)
59
60# Draw surf at the new coordinates
61screen.blit(surf, surf_center)
62pygame.display.flip()

5 to

$ python3 -m pygame.examples.aliens

27, it uses the coordinates of the top left corner to draw the surface. You’ll use this later to make your player move!

User Input

So far, you’ve learned how to set up

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 and draw objects on the screen. Now, the real fun starts! You’ll make the player controllable using the keyboard.

Earlier, you saw that

$ python3 -m pygame.examples.aliens

04 returns a list of the events in the event queue, which you scan for

$ python3 -m pygame.examples.aliens

00 event types. Well, that’s not the only way to read keypresses.

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 also provides

$ python3 -m pygame.examples.aliens

72, which returns a dictionary containing all the current

$ python3 -m pygame.examples.aliens

00 events in the queue.

Put this in your game loop right after the event handling loop. This returns a dictionary containing the keys pressed at the beginning of every frame:

$ python3 -m pygame.examples.aliens

2

Next, you write a method in

$ python3 -m pygame.examples.aliens

57 to accepts that dictionary. This will define the behavior of the sprite based off the keys that are pressed. Here’s what that might look like:

$ python3 -m pygame.examples.aliens

3

$ python3 -m pygame.examples.aliens

75,

$ python3 -m pygame.examples.aliens

76,

$ python3 -m pygame.examples.aliens

77, and

$ python3 -m pygame.examples.aliens

78 correspond to the arrow keys on the keyboard. If the dictionary entry for that key is

$ python3 -m pygame.examples.aliens

79, then that key is down, and you move the player

$ python3 -m pygame.examples.aliens

64 in the proper direction. Here you use

$ python3 -m pygame.examples.aliens

81, which stands for move in place, to move the current

54# Put the center of surf at the center of the display
55surf_center = (
56    (SCREEN_WIDTH-surf.get_width())/2,
57    (SCREEN_HEIGHT-surf.get_height())/2
58)
59
60# Draw surf at the new coordinates
61screen.blit(surf, surf_center)
62pygame.display.flip()

5.

Then you can call

$ python3 -m pygame.examples.aliens

83 every frame to move the player sprite in response to keypresses. Add this call right after the call to

$ python3 -m pygame.examples.aliens

84:

$ python3 -m pygame.examples.aliens

4

Now you can move your player rectangle around the screen with the arrow keys:

You may notice two small problems:

The player rectangle can move very fast if a key is held down. You’ll work on that later.
The player rectangle can move off the screen. Let’s solve that one now.

To keep the player on the screen, you need to add some logic to detect if the

$ python3 -m pygame.examples.aliens

26 is going to move off screen. To do that, you check whether the

$ python3 -m pygame.examples.aliens

26 coordinates have moved beyond the screen’s boundary. If so, then you instruct the program to move it back to the edge:

$ python3 -m pygame.examples.aliens

5

Here, instead of using

$ python3 -m pygame.examples.aliens

87, you just change the corresponding coordinates of

$ python3 -m pygame.examples.aliens

88,

$ python3 -m pygame.examples.aliens

89,

$ python3 -m pygame.examples.aliens

90, or

$ python3 -m pygame.examples.aliens

91 directly. Test this, and you’ll find the player rectangle can no longer move off the screen.

Now let’s add some enemies!

Remove ads

Enemies

What’s a game without enemies? You’ll use the techniques you’ve already learned to create a basic enemy class, then create a lot of them for your player to avoid. First, import the

$ python3 -m pygame.examples.aliens

92 library:

$ python3 -m pygame.examples.aliens

6

Then create a new sprite class called

$ python3 -m pygame.examples.aliens

93, following the same pattern you used for

$ python3 -m pygame.examples.aliens

57:

$ python3 -m pygame.examples.aliens

7

There are four notable differences between

$ python3 -m pygame.examples.aliens

93 and

$ python3 -m pygame.examples.aliens

57:

On lines 62 to 67, you update
```
$ python3 -m pygame.examples.aliens
```
26 to be a random location along the right edge of the screen. The center of the rectangle is just off the screen. It’s located at some position between 20 and 100 pixels away from the right edge, and somewhere between the top and bottom edges.
On line 68, you define
```
$ python3 -m pygame.examples.aliens
```
98 as a random number between 5 and 20. This specifies how fast this enemy moves towards the player.
On lines 73 to 76, you define
```
$ python3 -m pygame.examples.aliens
```
83. It takes no arguments since enemies move automatically. Instead,
```
$ python3 -m pygame.examples.aliens
```
83 moves the enemy toward the left side of the screen at the
```
$ python3 -m pygame.examples.aliens
```
98 defined when it was created.

On line 74, you check whether the enemy has moved off-screen. To make sure the

$ python3 -m pygame.examples.aliens

93 is fully off the screen and won’t just disappear while it’s still visible, you check that the right side of the

$ python3 -m pygame.examples.aliens

64 has gone past the left side of the screen. Once the enemy is off-screen, you call

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

04 to prevent it from being processed further.

So, what does

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

04 do? To figure this out, you have to know about Sprite Groups.

Sprite Groups

Another super useful class that

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 provides is the

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

07. This is an object that holds a group of

$ python3 -m pygame.examples.aliens

54 objects. So why use it? Can’t you just track your

$ python3 -m pygame.examples.aliens

54 objects in a list instead? Well, you can, but the advantage of using a

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

10 lies in the methods it exposes. These methods help to detect whether any

$ python3 -m pygame.examples.aliens

93 has collided with the

$ python3 -m pygame.examples.aliens

57, which makes updates much easier.

Let’s see how to create sprite groups. You’ll create two different

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

10 objects:

The first

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

10 will hold every

$ python3 -m pygame.examples.aliens

54 in the game.

The second

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

10 will hold just the

$ python3 -m pygame.examples.aliens

93 objects.

Here’s what that looks like in code:

$ python3 -m pygame.examples.aliens

8

When you call

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

04, the

$ python3 -m pygame.examples.aliens

54 is removed from every

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

10 to which it belongs. This removes the references to the

$ python3 -m pygame.examples.aliens

54 as well, which allows Python’s garbage collector to reclaim the memory as necessary.

Now that you have an

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

22 group, you can change how objects are drawn. Instead of calling

$ python3 -m pygame.examples.aliens

27 on just

$ python3 -m pygame.examples.aliens

57, you can iterate over everything in

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

22:

$ python3 -m pygame.examples.aliens

9

Now, anything put into

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

22 will be drawn with every frame, whether it’s an enemy or the player.

There’s just one problem… You don’t have any enemies! You could create a bunch of enemies at the beginning of the game, but the game would quickly become boring when they all left the screen a few seconds later. Instead, let’s explore how to keep a steady supply of enemies coming as the game progresses.

Custom Events

The design calls for enemies to appear at regular intervals. This means that at set intervals, you need to do two things:

Create a new
```
$ python3 -m pygame.examples.aliens
```
93.

Add it to

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

22 and

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

29.

You already have code that handles random events. The event loop is designed to look for random events occurring every frame and deal with them appropriately. Luckily,

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 doesn’t restrict you to using only the event types it has defined. You can define your own events to handle as you see fit.

Let’s see how to create a custom event that’s generated every few seconds. You can create a custom event by naming it:

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

0

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 defines events internally as integers, so you need to define a new event with a unique integer. The last event

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 reserves is called

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

33, so defining

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

34 on line 83 ensures it’s unique.

Next, you need to insert this new event into the event queue at regular intervals throughout the game. That’s where the

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

35 module comes in. Line 84 fires the new

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

36 event every 250 milliseconds, or four times per second. You call

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

37 outside the game loop since you only need one timer, but it will fire throughout the entire game.

Add the code to handle your new event:

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

1

Whenever the event handler sees the new

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

36 event on line 115, it creates an

$ python3 -m pygame.examples.aliens

93 and adds it to

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

29 and

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

22. Since

$ python3 -m pygame.examples.aliens

93 is in

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

22, it will get drawn every frame. You also need to call

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

44 on line 126, which updates everything in

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

29, to ensure they move properly:

However, that’s not the only reason there’s a group for just

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

29.

Remove ads

Collision Detection

Your game design calls for the game to end whenever an enemy collides with the player. Checking for collisions is a basic technique of game programming, and usually requires some non-trivial math to determine whether two sprites will overlap each other.

This is where a framework like

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 comes in handy! Writing collision detection code is tedious, but

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 has a LOT of collision detection methods available for you to use.

For this tutorial, you’ll use a method called

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

49, which is read as “sprite collide any.” This method accepts a

$ python3 -m pygame.examples.aliens

54 and a

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

10 as parameters. It looks at every object in the

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

10 and checks if its

$ python3 -m pygame.examples.aliens

64 intersects with the

$ python3 -m pygame.examples.aliens

64 of the

$ python3 -m pygame.examples.aliens

54. If so, then it returns

$ python3 -m pygame.examples.aliens

79. Otherwise, it returns

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

57. This is perfect for this game since you need to check if the single

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

58 collides with one of a

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

10 of

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

29.

Here’s what that looks like in code:

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

2

Line 135 tests whether

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

58 has collided with any of the objects in

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

29. If so, then

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

63 is called to remove it from every group to which it belongs. Since the only objects being rendered are in

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

22, the

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

58 will no longer be rendered. Once the player has been killed, you need to exit the game as well, so you set

$ python3 -m pygame.examples.aliens

05 to break out of the game loop on line 138.

At this point, you’ve got the basic elements of a game in place:

Now, let’s dress it up a bit, make it more playable, and add some advanced capabilities to help it stand out.

Sprite Images

Alright, you have a game, but let’s be honest… It’s kind of ugly. The player and enemies are just white blocks on a black background. That was state-of-the-art when Pong was new, but it just doesn’t cut it anymore. Let’s replace all those boring white rectangles with some cooler images that will make the game feel like an actual game.

Earlier, you learned that images on disk can be loaded into a

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7 with some help from the

54# Put the center of surf at the center of the display
55surf_center = (
56    (SCREEN_WIDTH-surf.get_width())/2,
57    (SCREEN_HEIGHT-surf.get_height())/2
58)
59
60# Draw surf at the new coordinates
61screen.blit(surf, surf_center)
62pygame.display.flip()

1 module. For this tutorial, we made a little jet for the player and some missiles for the enemies. You’re welcome to use this art, draw your own, or download some free game art assets to use. You can click the link below to download the art used in this tutorial:

Sample Code: Click here to download the source code for the PyGame sample project used in this tutorial.

Altering the Object Constructors

Before you use images to represent the player and enemy sprites, you need to make some changes to their constructors. The code below replaces the code used previously:

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

3

Let’s unpack line 31 a bit.

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

69 loads an image from the disk. You pass it a path to the file. It returns a

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7, and the

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

71 call optimizes the

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7, making future

$ python3 -m pygame.examples.aliens

27 calls faster.

Line 32 uses

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

74 to indicate the color

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 will render as transparent. In this case, you choose white, because that’s the background color of the jet image. The RLEACCEL constant is an optional parameter that helps

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 render more quickly on non-accelerated displays. This is added to the

20# Define a Player object by extending pygame.sprite.Sprite
21# The surface drawn on the screen is now an attribute of 'player'
22class Player(pygame.sprite.Sprite):
23    def __init__(self):
24        super(Player, self).__init__()
25        self.surf = pygame.Surface((75, 25))
26        self.surf.fill((255, 255, 255))
27        self.rect = self.surf.get_rect()

1 import statement on line 11.

Nothing else needs to change. The image is still a

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7, except now it has a picture painted on it. You still use it in the same way.

Here’s what similar changes to the

$ python3 -m pygame.examples.aliens

93 look like:

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

4

Running the program now should show that this is the same game you had before, except now you’ve added some nice graphics skins with images. But why stop at just making the player and enemy sprites look nice? Let’s add a few clouds going past to give the impression of a jet flying through the sky.

Remove ads

Adding Background Images

For background clouds, you use the same principles as you did for

$ python3 -m pygame.examples.aliens

57 and

$ python3 -m pygame.examples.aliens

93:

Create the

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

82 class.

Add an image of a cloud to it.

Create a method

$ python3 -m pygame.examples.aliens

83 that moves the

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

84 toward the left side of the screen.

Create a custom event and handler to create new

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

84 objects at a set time interval.

Add the newly created

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

84 objects to a new

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

10 called

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

88.

Update and draw the

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

88 in your game loop.

Here’s what

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

82 looks like:

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

5

That should all look very familiar. It’s pretty much the same as

$ python3 -m pygame.examples.aliens

93.

To have clouds appear at certain intervals, you’ll use event creation code similar to what you used to create new enemies. Put it right below the enemy creation event:

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

6

This says to wait 1000 milliseconds, or one second, before creating the next

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

84.

Next, create a new

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

10 to hold each newly created

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

84:

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

7

Next, add a handler for the new

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

95 event in the event handler:

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

8

Finally, make sure the

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

88 are updated every frame:

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

9

Line 172 updates the original

27# Variable to keep the main loop running
28running = True
29
30# Main loop
31while running:
32    # Look at every event in the queue
33    for event in pygame.event.get():
34        # Did the user hit a key?
35        if event.type == KEYDOWN:
36            # Was it the Escape key? If so, stop the loop.
37            if event.key == K_ESCAPE:
38                running = False
39
40        # Did the user click the window close button? If so, stop the loop.
41        elif event.type == QUIT:
42            running = False

0 to fill the screen with a pleasant sky blue color. You can change this color to something else. Maybe you want an alien world with a purple sky, a toxic wasteland in neon green, or the surface of Mars in red!

Note that each new

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

82 and

$ python3 -m pygame.examples.aliens

93 are added to

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

22 as well as

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

88 and

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

29. This is done because each group is used for a separate purpose:

Rendering is done using

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

22.

Position updates are done using

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

88 and

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

29.

Collision detection is done using

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

29.

You create multiple groups so that you can change the way sprites move or behave without impacting the movement or behavior of other sprites.

Game Speed

While testing the game you may have noticed that the enemies move a little fast. If not, then that’s okay, as different machines will see different results at this point.

The reason for this is that the game loop processes frames as fast as the processor and environment will allow. Since all the sprites move once per frame, they can move hundreds of times each second. The number of frames handled each second is called the frame rate, and getting this right is the difference between a playable game and a forgettable one.

Normally, you want as high a frame rate as possible, but for this game, you need to slow it down a bit for the game to be playable. Fortunately, the module

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

35 contains a

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

08 which is designed exactly for this purpose.

Using

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

08 to establish a playable frame rate requires just two lines of code. The first creates a new

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

08 before the game loop begins:

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

0

The second calls

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

11 to inform

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 that the program has reached the end of the frame:

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

1

The argument passed to

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

11 establishes the desired frame rate. To do this,

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

11 calculates the number of milliseconds each frame should take, based on the desired frame rate. Then, it compares that number to the number of milliseconds that have passed since the last time

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

11 was called. If not enough time has passed, then

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

11 delays processing to ensure that it never exceeds the specified frame rate.

Passing in a smaller frame rate will result in more time in each frame for calculations, while a larger frame rate provides smoother (and possibly faster) gameplay:

Play around with this number to see what feels best for you!

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Sound Effects

So far, you’ve focused on gameplay and the visual aspects of your game. Now let’s explore giving your game some auditory flavor as well.

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 provides

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

18 to handle all sound-related activities. You’ll use this module’s classes and methods to provide background music and sound effects for various actions.

The name

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

18 refers to the fact that the module mixes various sounds into a cohesive whole. Using the

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

20 sub-module, you can stream individual sound files in a variety of formats, such as MP3, Ogg, and Mod. You can also use

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

21 to hold a single sound effect to be played, in either Ogg or uncompressed WAV formats. All playback happens in the background, so when you play a

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

21, the method returns immediately as the sound plays.

Note: The

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 documentation states that MP3 support is limited, and unsupported formats can cause system crashes. The sounds referenced in this article have been tested, and we recommend testing any sounds thoroughly before releasing your game.

As with most things

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7, using

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

18 starts with an initialization step. Luckily, this is already handled by

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

3. You only need to call

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

27 if you want to change the defaults:

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

2

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

27 accepts a number of arguments, but the defaults work fine in most cases. Note that if you want to change the defaults, you need to call

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

27 before calling

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

3. Otherwise, the defaults will be in effect regardless of your changes.

After the system is initialized, you can get your sounds and background music setup:

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

3

Lines 138 and 139 load a background sound clip and begin playing it. You can tell the sound clip to loop and never end by setting the named parameter

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

31.

Lines 143 to 145 load three sounds you’ll use for various sound effects. The first two are rising and falling sounds, which are played when the player moves up or down. The last is the sound used whenever there is a collision. You can add other sounds as well, such as a sound for whenever an

$ python3 -m pygame.examples.aliens

93 is created, or a final sound for when the game ends.

So, how do you use the sound effects? You want to play each sound when a certain event occurs. For example, when the ship moves up, you want to play

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

33. Therefore, you add a call to

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

34 whenever you handle that event. In the design, that means adding the following calls to

$ python3 -m pygame.examples.aliens

83 for

$ python3 -m pygame.examples.aliens

57:

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

4

For a collision between the player and an enemy, you play the sound for when collisions are detected:

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

5

Here, you stop any other sound effects first, because in a collision the player is no longer moving. Then you play the collision sound and continue execution from there.

Finally, when the game is over, all sounds should stop. This is true whether the game ends due to a collision or the user exits manually. To do this, add the following lines at the end of the program after the loop:

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

6

Technically, these last few lines are not required, as the program ends right after this. However, if you decide later on to add an intro screen or an exit screen to your game, then there may be more code running after the game ends.

That’s it! Test it again, and you should see something like this:

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A Note on Sources

You may have noticed the comment on lines 136-137 when the background music was loaded, listing the source of the music and a link to the Creative Commons license. This was done because the creator of that sound required it. The license requirements stated that in order to use the sound, both proper attribution and a link to the license must be provided.

Here are some sources for music, sound, and art that you can search for useful content:

OpenGameArt.org: sounds, sound effects, sprites, and other artwork
Kenney.nl: sounds, sound effects, sprites, and other artwork
Gamer Art 2D: sprites and other artwork
CC Mixter: sounds and sound effects
Freesound: sounds and sound effects

As you make your games and use downloaded content such as art, music, or code from other sources, please be sure that you are complying with the licensing terms of those sources.

Conclusion

Throughout this tutorial, you’ve learned how game programming with

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 differs from standard procedural programming. You’ve also learned how to:

Implement event loops
Draw items on the screen
Play sound effects and music
Handle user input

To do this, you used a subset of the

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 modules, including the

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

0,

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

18 and

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

20,

 1# Simple pygame program
 2
 3# Import and initialize the pygame library
 4import pygame
 5pygame.init()
 6
 7# Set up the drawing window
 8screen = pygame.display.set_mode([500, 500])
 9
10# Run until the user asks to quit
11running = True
12while running:
13
14    # Did the user click the window close button?
15    for event in pygame.event.get():
16        if event.type == pygame.QUIT:
17            running = False
18
19    # Fill the background with white
20    screen.fill((255, 255, 255))
21
22    # Draw a solid blue circle in the center
23    pygame.draw.circle(screen, (0, 0, 255), (250, 250), 75)
24
25    # Flip the display
26    pygame.display.flip()
27
28# Done! Time to quit.
29pygame.quit()

35,

54# Put the center of surf at the center of the display
55surf_center = (
56    (SCREEN_WIDTH-surf.get_width())/2,
57    (SCREEN_HEIGHT-surf.get_height())/2
58)
59
60# Draw surf at the new coordinates
61screen.blit(surf, surf_center)
62pygame.display.flip()

1,

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

44, and

$ python3 -m pygame.examples.aliens

03 modules. You also used several

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 classes, including

54# Put the center of surf at the center of the display
55surf_center = (
56    (SCREEN_WIDTH-surf.get_width())/2,
57    (SCREEN_HEIGHT-surf.get_height())/2
58)
59
60# Draw surf at the new coordinates
61screen.blit(surf, surf_center)
62pygame.display.flip()

5,

44# Fill the screen with white
45screen.fill((255, 255, 255))
46
47# Create a surface and pass in a tuple containing its length and width
48surf = pygame.Surface((50, 50))
49
50# Give the surface a color to separate it from the background
51surf.fill((0, 0, 0))
52rect = surf.get_rect()

7,

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

21, and

$ python3 -m pygame.examples.aliens

54. But these only scratch the surface of what

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 can do! Check out the official

 1# Import the pygame module
 2import pygame
 3
 4# Import pygame.locals for easier access to key coordinates
 5# Updated to conform to flake8 and black standards
 6from pygame.locals import (
 7    K_UP,
 8    K_DOWN,
 9    K_LEFT,
10    K_RIGHT,
11    K_ESCAPE,
12    KEYDOWN,
13    QUIT,
14)
15
16# Initialize pygame
17pygame.init()

7 documentation for a full list of available modules and classes.

You can find all of the code, graphics, and sound files for this article by clicking the link below:

Sample Code: Click here to download the source code for the PyGame sample project used in this tutorial.

Feel free to leave comments below as well. Happy Pythoning!

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Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Make a 2D Side-Scroller Game With PyGame

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About Jon Fincher

Jon taught Python and Java in two high schools in Washington State. Previously, he was a Program Manager at Microsoft.

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Each tutorial at Real Python is created by a team of developers so that it meets our high quality standards. The team members who worked on this tutorial are:

Alex

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Christopher

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Jaya

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