Flappy Bird Game tutorial

Building Flappy Bird in Python: A Step-by-Step Guide

Introduction

Welcome to the ultimate Python tutorial for creating the iconic Flappy Bird game using Pygame. This guide is designed to help beginners not only code the game but also understand the logic behind each line of code. By the end, you’ll be equipped with the skills to extend and customize the game to your liking.

Getting Started
Setting Up the Environment
Understanding the Game Components
Building the Game Step-by-Step
Enhancements and Customization

1. Getting Started

Flappy Bird is a simple game where a bird avoids obstacles (pipes) and gains points by passing through gaps. Our game will include:

A bird sprite
Pipes as obstacles
A scrolling background
Score tracking
Sound effects

Prerequisites: Basic knowledge of Python and Pygame library installed. Use pip install pygame if you haven't already.

2. Setting Up the Environment

We start by importing the required modules, initializing Pygame, and setting up the game window.

# Import necessary modules
import pygame
import random
import time
import sys
 
# Initialize Pygame
pygame.init()
 
# Screen dimensions
scrn = pygame.display.set_mode((550, 900))
clock = pygame.time.Clock()
 
# Screen width and height
width, height = scrn.get_size()

Explanation:

pygame.init(): Initializes Pygame.
pygame.display.set_mode(): Creates the game window with a resolution of 550x900.
scrn.get_size(): Fetches screen dimensions for dynamic scaling.

3. Understanding the Game Components

Loading Assets

Load images and sounds required for the game.

images = {}
sound = {}
 
# Load number sprites for score display
images['numbers'] = (
    pygame.image.load('assets/sprites/0.png').convert_alpha(),
    pygame.image.load('assets/sprites/1.png').convert_alpha(),
    pygame.image.load('assets/sprites/2.png').convert_alpha(),
    pygame.image.load('assets/sprites/3.png').convert_alpha(),
    pygame.image.load('assets/sprites/4.png').convert_alpha(),
    pygame.image.load('assets/sprites/5.png').convert_alpha(),
    pygame.image.load('assets/sprites/6.png').convert_alpha(),
    pygame.image.load('assets/sprites/7.png').convert_alpha(),
    pygame.image.load('assets/sprites/8.png').convert_alpha(),
    pygame.image.load('assets/sprites/9.png').convert_alpha()
)
 
# Load game over screen image
images['gameover'] = pygame.image.load('assets/sprites/gameover.png').convert_alpha()
 
# Load bird sprite and scale it to fit the screen
images['players'] = pygame.transform.scale(
    pygame.image.load('assets/sprites/flappy.png').convert_alpha(), (15 * width / 100, 17 * width / 100)
)
 
# Load pipe sprites and scale them
images['pipe1'] = pygame.transform.scale(
    pygame.image.load('assets/sprites/pipe1.png').convert_alpha(), (400, height)
)
images['pipe2'] = pygame.transform.scale(
    pygame.image.load('assets/sprites/pipe2.png').convert_alpha(), (400, height)
)
 
# Load background and base images
images['background'] = pygame.transform.scale(
    pygame.image.load('assets/sprites/background.png').convert(), (width, height)
)
images['base'] = pygame.transform.scale(
    pygame.image.load('assets/sprites/base.png').convert_alpha(), (width + 10, int(height * 0.5))
)
 
# Load sounds
soundExt = '.wav'
sound['hit'] = pygame.mixer.Sound('assets/sounds/hit' + soundExt)
sound['point'] = pygame.mixer.Sound('assets/sounds/point' + soundExt)
sound['wing'] = pygame.mixer.Sound('assets/sounds/wing' + soundExt)

Explanation:

convert_alpha(): Optimizes the image for faster blitting and handles transparency.
pygame.mixer.Sound: Loads sound effects for game events like collisions and scoring.

Helper Functions

Displaying the Bird

def bird(playery, playerx, birdrot):
    image = pygame.transform.rotate(images['players'], birdrot)
    scrn.blit(image, (playerx, playery))

Rotates and displays the bird sprite at a specified position (playerx, playery).

Scrolling Base

def base(basey):
    scrn.blit(images['base'], (0 - 5, basey))

Displays the moving ground to create the illusion of motion.

Background Setup

def background():
    scrn.blit(images['background'], (0, 0))

Displays the background image.

Game Over Screen

def gameover():
    scrn.blit(images['gameover'], (gamex, gamey))
    pygame.display.update()

Displays the "Game Over" screen when the player crashes.

4. Building the Game Step-by-Step

Welcome Screen

The welcome screen is the entry point of the game, prompting the player to start.

def welcomescreen():
    scrn.fill((0, 0, 0))
    time.sleep(1)
    birdrot = 0
    basey = height * 0.67
    playery = height * 0.4
    playerx = width * 0.3
 
    bird(playery, playerx, birdrot)
    base(basey)
    pygame.display.update()
 
    while True:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                sys.exit()
            if event.type == pygame.MOUSEBUTTONDOWN or event.type == pygame.KEYDOWN:
                sound['wing'].play()
                return

Explanation:

Displays the bird and base at the start.
Waits for user input (mouse click or key press) to start the game.

Main Game Loop

This function manages the game’s core logic, including the bird’s movement, pipe generation, and collision detection.

def main():
    birdrot = 0
    score = 0
    basey = height * 0.67
    playery = height * 0.4
    playerx = width * 0.3
 
    playervel = -10
    playermaxvel = 20
    playeraccy = 2
    playeraccv = -12
    playerflapped = False
 
    # Initialize pipes
    newPipe1 = getRandomPipe()
    newPipe2 = getRandomPipe()
 
    upperPipes = [
        {'x': width + 200, 'y': newPipe1[0]['y']},
        {'x': width + 200 + (width / 2), 'y': newPipe2[0]['y']},
    ]
 
    lowerPipes = [
        {'x': width + 200, 'y': newPipe1[1]['y']},
        {'x': width + 200 + (width / 2), 'y': newPipe2[1]['y']},
    ]
 
    pipeVelX = -6
 
    while True:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                sys.exit()
            if event.type == pygame.MOUSEBUTTONDOWN or event.type == pygame.KEYDOWN:
                playervel = playeraccv
                playerflapped = True
                sound['wing'].play()
                birdrot = 23
 
        if playervel < playermaxvel and not playerflapped:
            playervel += playeraccy
        if playerflapped:
            playerflapped = False
 
        birdrot -= 2
        playery += playervel
 
        if crashtest(upperPipes, lowerPipes, playerx, playery):
            sound['hit'].play()
            gameover()
            time.sleep(1)
            return
 
        background()
        base(basey)
        bird(playery, playerx, birdrot)
 
        for uPipe, lPipe in zip(upperPipes, lowerPipes):
            scrn.blit(images['pipe1'], (uPipe['x'], uPipe['y']))
            scrn.blit(images['pipe2'], (lPipe['x'], lPipe['y']))
 
        showScore(score)
        clock.tick(32)
        pygame.display.update()

Explanation:

Updates bird’s position and checks for collisions.
Manages pipes by scrolling them to the left and adding new ones.
Displays the updated game state.

Generating Pipes

def getRandomPipe():
    basey = int(height * 0.67)
    pipex = width - 200
    gap = 100
    offset = int(height * 0.3)
 
    pipe1y = random.randint(offset, basey - 10)
    pipe2y = int(pipe1y - gap - images['pipe1'].get_height())
 
    return [
        {'x': pipex, 'y': pipe2y},
        {'x': pipex, 'y': pipe1y + gap},
    ]

5. Enhancements and Customization

Adding Sound: Use pygame.mixer.Sound to load and play sounds for more feedback.
Adding Images: Replace default sprites with custom designs.
Collision Tests: Refine crashtest to handle edge cases for improved gameplay.

Code:

import pygame
 
import random
import time
import sys
 
pygame.init()
scrn=pygame.display.set_mode((550,900))
clock=pygame.time.Clock()
 
width,height=scrn.get_size()
 
 
 
FPS=5
 
gamex=int(width*0.15)
gamey=int(height*0.3)
images={}
sound={}
 
 
images['numbers']=(
pygame.image.load('assets/sprites/0.png').convert_alpha(), 
pygame.image.load('assets/sprites/1.png').convert_alpha(), 
pygame.image.load('assets/sprites/2.png').convert_alpha(), 
pygame.image.load('assets/sprites/3.png').convert_alpha(), 
pygame.image.load('assets/sprites/4.png').convert_alpha(), 
pygame.image.load('assets/sprites/5.png').convert_alpha(), 
pygame.image.load('assets/sprites/6.png').convert_alpha(),
pygame.image.load('assets/sprites/7.png').convert_alpha(), 
pygame.image.load('assets/sprites/8.png').convert_alpha(), 
pygame.image.load('assets/sprites/9.png').convert_alpha()
)
 
 
images['gameover']=pygame.image.load('assets/sprites/gameover.png').convert_alpha()
 
images['players']=pygame.transform.scale(pygame.image.load('assets/sprites/flappy.png').convert_alpha(),(15*width/100,17*width/100))
 
images['pipe1']=pygame.transform.scale(pygame.image.load('assets/sprites/pipe1.png').convert_alpha(),(400,height))
images['pipe2']=pygame.transform.scale(pygame.image.load('assets/sprites/pipe2.png').convert_alpha(),(400,height))
 
images['background']=pygame.transform.scale(pygame.image.load('assets/sprites/background.png').convert(),(width,height))
 
images['base']=pygame.transform.scale(pygame.image.load('assets/sprites/base.png').convert_alpha(),(width+10,int(height*0.5)))
 
soundExt='.wav'
 
 
sound['hit'] = pygame.mixer.Sound('assets/sounds/hit' + soundExt)
 
sound['point'] = pygame.mixer.Sound('assets/sounds/point' + soundExt)
 
sound['wing'] = pygame.mixer.Sound('assets/sounds/wing' + soundExt)
 
def bird(playery,playerx,birdrot):
    image=pygame.transform.rotate(images['players'],birdrot)
    scrn.blit(image, (playerx,playery))
    
def base(basey):
    scrn.blit(images['base'], (0-5,basey))
def background():
    scrn.blit(images['background'], (0,0))    
 
def gameover():
     scrn.blit(images['gameover'],(gamex,gamey))
     pygame.display.update()
        
    
    
 
def welcomescreen():
    scrn.fill((0,0,0))
    time.sleep(1)
    birdrot=0
    basey = height*0.67
    playery=height*0.4
    playerx=width*0.3
    bird(playery,playerx,birdrot)
    base(basey)
    pygame.display.update()
    while True:
        #scrn.blit(images['pipe1'],(pipe[0]['x'],pipe[0]['y']))
        #pygame.display.update()
        #clock.tick(32)
        for event in pygame.event.get():
            if event.type==pygame.QUIT:
                pygame.quit()
                sys.exit()
            if event.type == pygame.MOUSEBUTTONDOWN or event.type==pygame.KEYDOWN:
                sound['wing'].play()
                return(9)
                        
def main(timet):
    birdrot=0
    score=0
    basey = height*0.67
    playery=height*0.4
    playerx=width*0.3
    
    playervel=-10
    playermaxvel=20
    playeraccy=2
    playeraccv=-12
    
    
    playerflapped=False
    
    newPipe1 = getRandomPipe()
    newPipe2 = getRandomPipe()
 
    # list of upper pipes
    upperPipes = [
        {
            'x': width + 200,
            'y': newPipe1[0]['y']
        },
        {
            'x': width + 200 + (width / 2),
            'y': newPipe2[0]['y']
        },
    ]
 
    # list of lowerpipe
    lowerPipes = [
        {
            'x': width + 200,
            'y': newPipe1[1]['y']
        },
        {
            'x': width + 200 + (width / 2),
            'y': newPipe2[1]['y']
        },
    ]
 
    pipeVelX = -6
    
    while True:
        if int(time.time()-timet)>2:
            score += 1
            sound['point'].play()
 
            timet=time.time()                                
 
 
                                                                         
        
        for event in pygame.event.get():
            if event.type==pygame.QUIT:
                pygame.quit()
                sys.exit()            
            if event.type == pygame.MOUSEBUTTONDOWN or event.type==pygame.KEYDOWN:
                playervel=playeraccv
                playerflapped=True
                sound['wing'].play()
                birdrot=23
        if playervel<playermaxvel and not playerflapped:
            playervel+=playeraccy
        if playerflapped:
            playerflapped=False
            
        
        
        birdrot-=2
 
                
                
        
            # player move
        if crashtest(upperPipes,lowerPipes,playerx,playery):
            sound['hit'].play()
            gameover()
            time.sleep(1)
            return 'gameover'
            
            
  
        
        
              
            
        playerHeight = images['players'].get_height()
        playery += playervel
        background()
        base(basey)
        bird(playery,playerx,birdrot)
        showScore
        for uPipe, lPipe in zip(upperPipes, lowerPipes):
            uPipe['x'] += pipeVelX
            lPipe['x'] += pipeVelX
   
       
 
            
            
            
            
            
                   #remove pipe             
        if len(upperPipes) > 0 and upperPipes[0]['x'] < -images['pipe1'].get_width():
            upperPipes.pop(0)
            lowerPipes.pop(0)
            newPipe = getRandomPipe()
            upperPipes.append(newPipe[0])
            lowerPipes.append(newPipe[1])          
             
            
            
            
        for uPipe, lPipe in zip(upperPipes, lowerPipes):
            scrn.blit(images['pipe1'], (uPipe['x'], uPipe['y']))
            scrn.blit(images['pipe2'] , (lPipe['x'], lPipe['y']))            
                        
        showScore(score)
        clock.tick(32)
        pygame.display.update()          
            
            
def getRandomPipe():
    basey=int(height*0.67)
    pipex=width-200
    gap=100
    offset=int(height*0.3)
    pipe1y=random.randint(offset,basey-10)
    pipe2y=int(pipe1y-gap-images['pipe1'].get_height())
    
    return [
    {'x':pipex , 'y':pipe2y},
    {'x':pipex , 'y':pipe1y+gap}
    ]
 
 
def crashtest(upperpipes,lowerpipes,playerx,playery):
    basey=int(height*0.67)
    if playery-85>=basey:
        return True
    for Upipe,Lpipe in zip(upperpipes,lowerpipes):
        if Upipe['x']>0:
            if (playerx+12)>Upipe['x']+47:
                if playery>Lpipe['y']-50 or playery<Upipe['y']+images['pipe1'].get_height()-50:
                    return True
def showScore(score):
    """displays score in center of screen"""
    scoreDigits = [int(x) for x in list(str(score))]
    totalWidth = 0  # total width of all numbers to be printed
 
    for digit in scoreDigits:
        totalWidth += images['numbers'][digit].get_width()
 
    Xoffset = (width - totalWidth) / 2
 
    for digit in scoreDigits:
        scrn.blit(images['numbers'][digit], (Xoffset, height * 0.1))
        Xoffset += images['numbers'][digit].get_width()
        
                                        
while True:
    welcomescreen()
    start=time.time()
    main(start)

Happy coding! Experiment with new features like power-ups, additional levels, or even multiplayer support.

Flappy Bird Game tutorial

Building Flappy Bird in Python: A Step-by-Step Guide

Introduction

Table of Contents

1. Getting Started

2. Setting Up the Environment

Explanation:

3. Understanding the Game Components

Loading Assets

Explanation:

Helper Functions

Displaying the Bird

Scrolling Base

Background Setup

Game Over Screen

4. Building the Game Step-by-Step

Welcome Screen

Explanation:

Main Game Loop

Explanation:

Generating Pipes

5. Enhancements and Customization

Code:

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