How to Detect Collisions in Pygame

In this Pygame article we want to learn How to Detect Collisions in Pygame, Collisions are an important part of many games and applications, and Pygame provides a number of tools for handling them. In this article we want to talk that how to handle collisions in Pygame.

This is the complete code for this article

import pygame
import random

# Initialize Pygame
pygame.init()

# Set up the screen
screen_width = 800
screen_height = 600
screen = pygame.display.set_mode((screen_width, screen_height))
pygame.display.set_caption("Collision Detection Example")

# Set up the clock
clock = pygame.time.Clock()

# Define colors
white = (255, 255, 255)
black = (0, 0, 0)
red = (255, 0, 0)


# Define the Player sprite class
class Player(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.image = pygame.Surface((50, 50))
        self.image.fill(white)
        self.rect = self.image.get_rect()
        self.rect.center = (screen_width // 2, screen_height // 2)
        self.speed = 5

    def update(self):
        # Move the player
        keys = pygame.key.get_pressed()
        if keys[pygame.K_LEFT]:
            self.rect.x -= self.speed
        elif keys[pygame.K_RIGHT]:
            self.rect.x += self.speed
        if keys[pygame.K_UP]:
            self.rect.y -= self.speed
        elif keys[pygame.K_DOWN]:
            self.rect.y += self.speed

        # Keep the player on the screen
        if self.rect.left < 0:
            self.rect.left = 0
        elif self.rect.right > screen_width:
            self.rect.right = screen_width
        if self.rect.top < 0:
            self.rect.top = 0
        elif self.rect.bottom > screen_height:
            self.rect.bottom = screen_height


# Define the Enemy sprite class
class Enemy(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.image = pygame.Surface((30, 30))
        self.image.fill(red)
        self.rect = self.image.get_rect()
        self.rect.x = random.randrange(screen_width - self.rect.width)
        self.rect.y = random.randrange(-100, -40)
        self.speed = random.randrange(1, 5)

    def update(self):
        # Move the enemy down the screen
        self.rect.y += self.speed

        # Respawn the enemy if it goes off the bottom of the screen
        if self.rect.top > screen_height + 10:
            self.rect.x = random.randrange(screen_width - self.rect.width)
            self.rect.y = random.randrange(-100, -40)
            self.speed = random.randrange(1, 5)


# Set up the sprite groups
all_sprites = pygame.sprite.Group()
enemies = pygame.sprite.Group()

# Create the player sprite and add it to the all_sprites group
player = Player()
all_sprites.add(player)

# Create the enemy sprites and add them to the all_sprites and enemies groups
for i in range(10):
    enemy = Enemy()
    all_sprites.add(enemy)
    enemies.add(enemy)

# Game loop
running = True
while running:
    # Handle events
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    # Update the sprites
    all_sprites.update()

    # Detect collisions between the player and enemies
    collisions = pygame.sprite.spritecollide(player, enemies, True)
    for enemy in collisions:
        # Handle the collision
        player.speed -= 1

    # Draw the screen
    screen.fill(black)
    all_sprites.draw(screen)
    pygame.display.flip()

    # Wait for the next frame
    clock.tick(60)

# Quit Pygame
pygame.quit()

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import pygame

import random

# Initialize Pygame

pygame.init()

# Set up the screen

screen_width = 800

screen_height = 600

screen = pygame.display.set_mode((screen_width, screen_height))

pygame.display.set_caption("Collision Detection Example")

# Set up the clock

clock = pygame.time.Clock()

# Define colors

white = (255, 255, 255)

black = (0, 0, 0)

red = (255, 0, 0)

# Define the Player sprite class

class Player(pygame.sprite.Sprite):

def __init__(self):

super().__init__()

self.image = pygame.Surface((50, 50))

self.image.fill(white)

self.rect = self.image.get_rect()

self.rect.center = (screen_width // 2, screen_height // 2)

self.speed = 5

def update(self):

# Move the player

keys = pygame.key.get_pressed()

if keys[pygame.K_LEFT]:

self.rect.x -= self.speed

elif keys[pygame.K_RIGHT]:

self.rect.x += self.speed

if keys[pygame.K_UP]:

self.rect.y -= self.speed

elif keys[pygame.K_DOWN]:

self.rect.y += self.speed

# Keep the player on the screen

if self.rect.left < 0:

self.rect.left = 0

elif self.rect.right > screen_width:

self.rect.right = screen_width

if self.rect.top < 0:

self.rect.top = 0

elif self.rect.bottom > screen_height:

self.rect.bottom = screen_height

# Define the Enemy sprite class

class Enemy(pygame.sprite.Sprite):

def __init__(self):

super().__init__()

self.image = pygame.Surface((30, 30))

self.image.fill(red)

self.rect = self.image.get_rect()

self.rect.x = random.randrange(screen_width - self.rect.width)

self.rect.y = random.randrange(-100, -40)

self.speed = random.randrange(1, 5)

def update(self):

# Move the enemy down the screen

self.rect.y += self.speed

# Respawn the enemy if it goes off the bottom of the screen

if self.rect.top > screen_height + 10:

self.rect.x = random.randrange(screen_width - self.rect.width)

self.rect.y = random.randrange(-100, -40)

self.speed = random.randrange(1, 5)

# Set up the sprite groups

all_sprites = pygame.sprite.Group()

enemies = pygame.sprite.Group()

# Create the player sprite and add it to the all_sprites group

player = Player()

all_sprites.add(player)

# Create the enemy sprites and add them to the all_sprites and enemies groups

for i in range(10):

enemy = Enemy()

all_sprites.add(enemy)

enemies.add(enemy)

# Game loop

running = True

while running:

# Handle events

for event in pygame.event.get():

if event.type == pygame.QUIT:

running = False

# Update the sprites

all_sprites.update()

# Detect collisions between the player and enemies

collisions = pygame.sprite.spritecollide(player, enemies, True)

for enemy in collisions:

# Handle the collision

player.speed -= 1

# Draw the screen

screen.fill(black)

all_sprites.draw(screen)

pygame.display.flip()

# Wait for the next frame

clock.tick(60)

# Quit Pygame

pygame.quit()

This code is simple example of a Pygame program that demonstrates collision detection between the player and enemy sprites. it starts by importing the Pygame module and the random module. after that it initializes Pygame and sets up the screen with a width of 800 pixels and a height of 600 pixels. screen is also given a caption of Collision Detection Example.

After that the clock is set up to help regulate the frame rate of the game. three colors are defined using RGB values.

Two sprite classes are defined for the player and the enemy. Player class has an image with dimensions of 50×50 pixels and is centered on the screen. It also has a speed value of 5 pixels per frame. enemy class has an image with dimensions of 30×30 pixels and is randomly placed at the top of the screen with a random speed between 1 and 5 pixels per frame.

After that sprite groups are set up. all_sprites group contains both the player and the enemies. enemies group only contains the enemies.

our program also enters a game loop, where it first handles events like the user closing the window. after that it updates all of the sprites and checks for collisions between the player and the enemies using the spritecollide method.

If a collision is detected, the player speed is decreased by 1 pixel per frame. screen is then filled with black and all of the sprites are drawn on the screen. and lastly Pygame display is updated with the latest changes and the program waits for the next frame. once the user closes the window or quits the program, Pygame is properly quit.

Run the code and this will be the result