Module 18 - Making a Game in Python

What is Pygame?

Pygame is a cross-platform set of Python modules designed for writing video games. It is built on top of the Simple DirectMedia Layer (SDL) library and provides easy-to-use functions and classes for game development. With Pygame, you can handle graphics, sound, input devices, and other game-related functionalities.

Setting up Pygame

Before starting, ensure that you have Pygame installed. You can install it using pip:

pip install pygame

Importing the necessary modules

To get started, we need to import the Pygame module and other required libraries:

import pygame
import random
import sys

Initializing Pygame

Next, we need to initialize Pygame to use its features:

pygame.init()

Setting up the game window

Let's create the game window and set its dimensions:

# Set the window dimensions
WINDOW_WIDTH, WINDOW_HEIGHT = 800, 600

# Create the game window
screen = pygame.display.set_mode((WINDOW_WIDTH, WINDOW_HEIGHT))
pygame.display.set_caption("Basic 2D Game")
 

Loading and displaying the player's image

In this step, we will load the player's image and display it on the screen:

# Load the player image
player_image = pygame.image.load("player.png")

# Get the rect of the player image for positioning
player_rect = player_image.get_rect()

# Position the player at the center of the screen vertically and near the bottom horizontally
player_rect.midbottom = (WINDOW_WIDTH // 2, WINDOW_HEIGHT - 20)

# Function to draw the player on the screen
def draw_player():
   screen.blit(player_image, player_rect)

Handling user input for movement

Now, let's implement the logic to handle user input and move the player:

# Player movement speed
player_speed = 5


# Function to update player movement
def update_player():
    # Get the state of the keyboard keys
    keys = pygame.key.get_pressed()

    # Move player left
    if keys[pygame.K_LEFT] and player_rect.left > 0:
        player_rect.x -= player_speed

    # Move player right
    if keys[pygame.K_RIGHT] and player_rect.right < WINDOW_WIDTH:
        player_rect.x += player_speed
 

Creating enemy sprites

Let's create enemy sprites that will be randomly spawned:

# Load the enemy image
enemy_image = pygame.image.load("enemy.png")

# List to store enemy rectangles
enemies = []

# Function to create a new enemy
def create_enemy():
   enemy_rect = enemy_image.get_rect()
   enemy_rect.topleft = (random.randint(0, WINDOW_WIDTH - enemy_rect.width), 0)
   enemies.append(enemy_rect)

Randomly spawning enemies

Now, we will randomly spawn enemies at regular intervals:

# Enemy spawn timer
SPAWN_ENEMY_EVENT = pygame.USEREVENT
pygame.time.set_timer(SPAWN_ENEMY_EVENT, 1000)  # Spawn an enemy every 1000 milliseconds

# Function to update enemy positions and spawn new enemies
def update_enemies():
   for enemy_rect in enemies[:]:
       enemy_rect.y += 5  # Move enemy down
       if enemy_rect.top > WINDOW_HEIGHT:
           enemies.remove(enemy_rect)

   for event in pygame.event.get():
       if event.type == SPAWN_ENEMY_EVENT:
           create_enemy()

Collision detection

Implement collision detection between the player and enemies:

def check_collision():
   for enemy_rect in enemies:
       if player_rect.colliderect(enemy_rect):
           return True
   return False
 

Introduction to the game loop

A game loop is a fundamental concept in game development. It is responsible for updating the game state and rendering the game elements.

# Game loop variables
FPS = 60
clock = pygame.time.Clock()

Updating game elements

Now, let's update the game elements inside the game loop:

def update_game():
   update_player()
   update_enemies()
   if check_collision():
       # Game over logic (to be implemented later)
       pass

Drawing elements to the screen

Finally, we will draw the game elements to the screen inside the game loop:

def draw_game():
   screen.fill((0, 0, 0))  # Fill the screen with black color
   draw_player()

   for enemy_rect in enemies:
       screen.blit(enemy_image, enemy_rect)

   # Update the display
   pygame.display.flip()

Keeping score

Let's implement a simple scoring mechanism:

score = 0
SCORE_FONT = pygame.font.Font(None, 36)

def update_score():
   global score
   score += 1

Displaying the score on the screen

Show the score on the game window:

def draw_score():
   score_surface = SCORE_FONT.render(f"Score: {score}", True, (255, 255, 255))
   screen.blit(score_surface, (10, 10))

Implementing a game over state

Let's create a game over screen and end the game when the player collides with an enemy:

def show_game_over():
   game_over_surface = SCORE_FONT.render("Game Over", True, (255, 0, 0))
   screen.blit(game_over_surface, (WINDOW_WIDTH // 2 - 100, WINDOW_HEIGHT // 2))
   pygame.display.flip()
   pygame.time.delay(2000)  # Show the game over screen for 2 seconds
   pygame.quit()
   sys.exit()

import pygame
import random
import sys

pygame.init()

# Set the window dimensions
WINDOW_WIDTH, WINDOW_HEIGHT = 800, 600

# Create the game window
screen = pygame.display.set_mode((WINDOW_WIDTH, WINDOW_HEIGHT))
pygame.display.set_caption("Basic 2D Game")

# Load the player image
player_image = pygame.image.load("player.png")
player_rect = player_image.get_rect()
player_rect.midbottom = (WINDOW_WIDTH // 2, WINDOW_HEIGHT - 20)
player_speed = 5

# Load the enemy image
enemy_image = pygame.image.load("enemy.png")
enemies = []

# Enemy spawn timer
SPAWN_ENEMY_EVENT = pygame.USEREVENT
pygame.time.set_timer(SPAWN_ENEMY_EVENT, 1000)

# Game loop variables
FPS = 60
clock = pygame.time.Clock()

# Score
score = 0
SCORE_FONT = pygame.font.Font(None, 36)

def create_enemy():
    enemy_rect = enemy_image.get_rect()
    enemy_rect.topleft = (random.randint(0, WINDOW_WIDTH - enemy_rect.width), 0)
    enemies.append(enemy_rect)

def update_enemies():
    for enemy_rect in enemies[:]:
        enemy_rect.y += 5
        if enemy_rect.top > WINDOW_HEIGHT:
            enemies.remove(enemy_rect)

    for event in pygame.event.get():
        if event.type == SPAWN_ENEMY_EVENT:
            create_enemy()

def draw_player():
    screen.blit(player_image, player_rect)

def draw_score():
    score_surface = SCORE_FONT.render(f"Score: {score}", True, (255, 255, 255))
    screen.blit(score_surface, (10, 10))

def check_collision():
    for enemy_rect in enemies:
        if player_rect.colliderect(enemy_rect):
            return True
    return False

def update_player():
    keys = pygame.key.get_pressed()
    if keys[pygame.K_LEFT] and player_rect.left > 0:
        player_rect.x -= player_speed
    if keys[pygame.K_RIGHT] and player_rect.right < WINDOW_WIDTH:
        player_rect.x += player_speed

def update_score():
    global score
    score += 1

def show_game_over():
    game_over_surface = SCORE_FONT.render("Game Over", True, (255, 0, 0))
    screen.blit(game_over_surface, (WINDOW_WIDTH // 2 - 100, WINDOW_HEIGHT // 2))
    pygame.display.flip()
    pygame.time.delay(2000)
    pygame.quit()
    sys.exit()

def update_game():
    update_player()
    update_enemies()
    update_score()
    if check_collision():
        show_game_over()

def draw_game():
    screen.fill((0, 0, 0))
    draw_player()

    for enemy_rect in enemies:
        screen.blit(enemy_image, enemy_rect)

    draw_score()

    pygame.display.flip()

# Game loop
while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()

    update_game()
    draw_game()
    clock.tick(FPS)