A little explanation of how to use the basics of pygame

1-pygame.md

pygame

pygame is a game framework for python. It can be used for creating many 2D games.

Contents

• basic-window.py - Opening up a basic window
• rectangle.py - Drawing a rectangle on the window
• follow.py - Making a circle follow your cursor.

2-basic-window.py

import pygame

pygame.init()
# You must call init() at the start of every pygame
# project that you make.

WIDTH = 500
HEIGHT = 500
# You can change these variables to what you like,
# they represent the height and width of your window.

display = pygame.display.set_mode((WIDTH, HEIGHT))
print("Created the window.")

pygame.display.set_caption("basic-window.py")
# This sets the window title, you can change this as well.

clock = pygame.time.Clock()

stopped = False

while not stopped:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            # This event fires if the user clicks the
            # red X or closes the window some other way
            # e.g. pressing alt+f4
            print("Destroying the window")
            stopped = True
            # Set stopped to True to break out of
            # our main loop.
            
        clock.tick(60)
        # This means this we will loop through the events
        # 60 times every second.

pygame.quit()
# Quit our program at the end

3-rectangle.py

import pygame

pygame.init()

WIDTH = 500
HEIGHT = 500

display = pygame.display.set_mode((WIDTH, HEIGHT))
print("Created the window.")

pygame.display.set_caption("rectangle.py")

clock = pygame.time.Clock()

# To draw a rectangle we need to create a pygame.Rect object.
# pygame.Rect can take in two tuples:
# 1. The x and y position (top left is (0, 0))
# 2. The width and height of the rectangle
rectangle = pygame.Rect((100, 100), (200, 100))

# To draw the rectangle onto the window we need to use another
# function: pygame.draw.rect. This takes in the following parameters:
# surface: in our case this is the "display" variable we created earlier
# colour: a tuple of the r, g and b values e.g. (255, 0, 0) for red
# rect: a pygame.Rect object, in our case this is the "rectangle variable"
pygame.draw.rect(display, (255, 0, 0), rectangle)

# After doing this we must update the display
pygame.display.update()

# It is not just rectangles that you can draw but many other shapes
# and they are listed below in "shapes.md"

stopped = False

while not stopped:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            print("Destroying the window")
            stopped = True

            
        clock.tick(60)

pygame.quit()

4-shapes.md

Shapes

A list of shapes that you can draw with pygame.draw

Rectangle

Function: pygame.draw.rect

Parameters:

• surface - the surface to draw on (the variable we called display in the above files)
• color - a tuple of the color's rgb values e.g. (255, 0, 0) for red
• rect - a pygame.Rect object

Circle

Function: pygame.draw.circle

Parameters:

• surface - the surface to draw on (the variable we called display in the above files)
• color - a tuple of the color's rgb values e.g. (255, 0, 0) for red
• center - a tuple denoting the x, y coordinates of the centre of the circle
• radius - the radius of the circle

Ellipse

Function: pygame.draw.ellipse

Parameters: The same as pygame.draw.rect but it draws an ellipse instead of a rectangle

Polygon

Function: pygame.draw.polygon

Parameters:

• surface - the surface to draw on (the variable we called display in the above files)
• color - a tuple of the color's rgb values e.g. (255, 0, 0) for red
• points - a list of tuples denoting the vertices of the polygon

Line

Function: pygame.draw.line

Parameters:

• surface - the surface to draw on (the variable we called display in the above files)
• color - a tuple of the color's rgb values e.g. (255, 0, 0) for red
• start_pos - a tuple denoting the x, y coordinates of the starting position of the line
• end_pos - a tuple denoting the x, y coordinates of the ending position of the line
• width - the width of the line

5-follow.py

import pygame

pygame.init()

WIDTH = 500
HEIGHT = 500

display = pygame.display.set_mode((WIDTH, HEIGHT))
print("Created the window.")

pygame.display.set_caption("follow.py")

clock = pygame.time.Clock()


def circle(display, position):
    # This fills the screen with one colour. If we don't do this
    # then all the circles that were drawn last time will still be there.
    display.fill((0, 0, 0))
    
    # Draw a circle onto the display.
    # pygame.draw.circle takes in the display, colour,
    # position and the radius
    pygame.draw.circle(display, (255, 0, 0), position, 25)
    pygame.display.update()

stopped = False

while not stopped:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            print("Destroying the window")
            stopped = True
        if event.type == pygame.MOUSEMOTION:
            # This event is fired when we move our mouse over the screen
            # it has a "pos" attribute which denotes where the mouse moved to
            # we can use this to pass to the function that was created earlier
            circle(display, event.pos)
        
        clock.tick(60)

pygame.quit()