AirForce

This is a simple python game write with pyGame. For educational purpose, I used 3 different way to build the game.

• Part 1, Implements with the basic game loop and basic game object.
• Part 2, Rewrote the code with Object-Oriented Programming (OOP) style.
• Part 3, Use prompts to let the Cursor AI to build the AirForce game.

Part 1: Build Game with basic game loop and basic game object

• Step 1: Initialize PyGame
• Step 2: Load Background and Additional Objects
• Step 3: Make the Player Move with AWSD Key Press
• Step 4: Let the Airplane Fire Bullets
• Step 5: Add Enemies
• Step 6: Check for Collisions
• Step 7: Add Explosion Animation
• Step 8: Load Sound and Play Music
• Step 9: Draw Text for Score, Life, and Game Over

Step1 Initial the PYGame

• Create a project folder, and add a images folder in the project folder \yourProject\ \yourProject\images\

• Prepare a image for the player of your game:

Hint: You could use the https://www.remove.bg/ to remove background of your images for game

• Create a py file with below code

# step 1, init the game and load image

# 1.1 - Import library
import pygame

# 1.2 - Initialize the game 
pygame.init()
width, height = 640, 480
screen=pygame.display.set_mode((width, height))
keep_going = True

# 1.3 - Load images
player = pygame.image.load("images/player.png")

# 1.4 - use loop to keep the game running 
while keep_going:
    # 1.5 - clear the screen before drawing it again
    screen.fill(0)
    #1.6 - draw the screen elements
    screen.blit(player, (100,100))
    #1.7 - update the screen
    pygame.display.flip() # will update the contents of the entire display, and faster than .update()
    # 1.8 - loop through the events
    for event in pygame.event.get():
        # check if the event is the X button
        if event.type==pygame.QUIT:
            keep_going = False
            

#1.9 exit pygame and python
pygame.quit()
exit(0) 

Source Code of Step1

2 Step 2: Load background and additional objects

• Prepare images of a background background = pygame.image.load("images/sky.jpg")

  There are different ways to load background,

  1. you could use one big image screen.blit(background,(0,0))

  2. you could change your image to fit the screen size background = pygame.transform.scale(background, (width, height))

  3. if you image is small, you need use double loop to fill the background

    for x in range( int(width/background.get_width())+1):
        for y in range(int(height/background.get_height())+1):
            screen.blit(background,(x*100,y*100))
  

  

• Prepare a air balloon as cargo you need protect

  • cargo = pygame.image.load("images/airballoon.png")

  • Load multiple cargo

    screen.blit(cargo,(0,30))
    screen.blit(cargo,(0,135))
    screen.blit(cargo,(0,240))
    screen.blit(cargo,(0,345))
    

  • do yourself: use list and loop to load air balloon

  ##initial
  balloons=[]
  for(i in range(4)):
      balloons.append([0,(30+i*100)])
  # in run loop
  for(balloonPos in balloons):
     screen.blit(cargo,balloonPos) 
  

• The full code example

#Step2, Load background and cargo
import pygame

pygame.init()
width, height = 640, 480
screen=pygame.display.set_mode((width, height))
keep_going = True


player = pygame.image.load("images/player.png")

#---------------------------------------------
#2.1 load more images
background = pygame.image.load("images/sky.jpg")
cargo = pygame.image.load("images/airballoon.png")
#---------------------------------------------

while keep_going:

    screen.fill(0)
    
    #----------------------------------------
    #2.2 load the background
    screen.blit(background,(0,0))
    # if you image is small, you need use double loop to fill the background
    #for x in range( int(width/background.get_width())+1):
    #    for y in range(int(height/background.get_height())+1):
    #        screen.blit(background,(x*100,y*100))
    
    # 2.3 load the balloon cargo
    screen.blit(cargo,(0,30))
    screen.blit(cargo,(0,135))
    screen.blit(cargo,(0,240))
    screen.blit(cargo,(0,345))
    #----------------------------------------

    screen.blit(player, (130,100))
    
    pygame.display.flip() 
    
    for event in pygame.event.get():
        if event.type==pygame.QUIT:
            keep_going = False

pygame.quit()
exit(0)

SourceCode of Step 2

Step 3: Make the player moving with AWSD key press

• 3.1 initial the value of Key and position

key_up=key_down=key_left=key_right = False
player_pos=[130,100]

• 3.2 in running loop, set the player position

  screen.blit(player, player_pos)

• 3.3 the Event driven code use the pygame.KEYDOWN

  #3.3 monitor the key down and up
    for event in pygame.event.get():
        if event.type==pygame.QUIT:
            keep_going = False
        if event.type == pygame.KEYDOWN:
            if event.key==pygame.K_w:
                key_up=True
            elif event.key==pygame.K_a:
                key_left=True
            elif event.key==pygame.K_s:
                key_down=True
            elif event.key==pygame.K_d:
                key_right=True
        if event.type == pygame.KEYUP:
            if event.key==pygame.K_w:
                key_up=False
            elif event.key==pygame.K_a:
                key_left=False
            elif event.key==pygame.K_s:
                key_down=False
            elif event.key==pygame.K_d:
                key_right=False
  

• 3.4 change the player position base on the key status

    if key_up:
        player_pos[1]-=1
    elif key_down:
        player_pos[1]+=1
    if key_left:
        player_pos[0]-=1
    elif key_right:
        player_pos[0]+=1
  

Add more code to limited the position of player could move

    if key_up and player_pos[1]>0:
        player_pos[1]-=1
    elif key_down and player_pos[1]<height-30:
        player_pos[1]+=1
    if key_left and player_pos[0]>0:
        player_pos[0]-=1
    elif key_right and player_pos[0]<width-100:
        player_pos[0]+=1

Source Code of Step 3

Step4: Let air plane fire bullet

• Prepare the bullet

    #initial bullets
    bullets=[]
    bullet = pygame.image.load("images/bullet.png")
  

• Draw the bullet in screen

  ```python #4 - Draw bullet index=0 for bulletPos in bullets:

    bulletPos[0]=bulletPos[0]+1
    screen.blit(bullet,bulletPos)
  
    #remove bullet if out the screen
    if bulletPos[0]<-64 or bulletPos[0]>640 or bulletPos[1]<-64 or bulletPos[1]>480:
        bullets.pop(index)  #remove from list
    index+=1  
  

- Mouse Click or space key down to fire

```python
    # use mouse click or space to fire         
    if event.type==pygame.MOUSEBUTTONDOWN or (event.type==pygame.KEYDOWN and event.key==pygame.K_SPACE):
        bullets.append([player_pos[0],player_pos[1]]) 

Source Code of Step4

Step 5: Add Enemies

• Prepare images for enemies
  

• initial the code for Enemies

#5 initial enemies
    enemyImg = pygame.image.load("images/enemy2.png")
    enemys=[[640,100]]
    enemySpeed=-0.5
    enemyMaxnumber=5 #how many enemies in the screen same time

• in the keep_going loop , draw enemies

 #5 Draw enemies random time and only keep 5 enemies in screen
    if(random.randint(1,100)<3 and len(enemys)<enemyMaxnumber): 
        enemys.append([640, random.randint(50,430)]) 

    index=0
    for enemyPos in enemys:               
        enemyPos[0]+=enemySpeed
        if enemyPos[0]<50:
            enemys.pop(index)
        screen.blit(enemyImg, enemyPos)
        index+=1   
#end step 5

• Load a different Enemy image

    #5 enemy
    enemyImg = pygame.image.load("images/enemy1.png")
    enemyImg=pygame.transform.scale(enemyImg, (75, 75))
    enemys=[[640,100]]
    enemySpeed=-0.3
    enemyMaxnumber=5

• Add code remove enemies

#4 - Draw bullet
    enemy_index=0
    for bulletPos in bullets:    
        bulletPos[0]=bulletPos[0]+2
        screen.blit(bullet,bulletPos)

        #remove bullet if out the screen
        if bulletPos[0]<-64 or bulletPos[0]>640 or bulletPos[1]<-64 or bulletPos[1]>480:
            bullets.pop(enemy_index)  #remove from list
        enemy_index+=1

• results

Code with step 5

Step 6: Check the collision

• update code in the loop of enemies

    enemy_index=0
    for enemyPos in enemys:               
        enemyPos[0]+=enemySpeed
        if enemyPos[0]<50:
            enemys.pop(enemy_index)
        screen.blit(enemyImg, enemyPos)
        
    # 6 Check for collisions
        enemyRect=pygame.Rect(enemyImg.get_rect())
        enemyRect.left=enemyPos[0]
        enemyRect.top=enemyPos[1]
        bullet_index=0
        for bulletPos in bullets:
            bulletRect=pygame.Rect(bullet.get_rect()) # get rect of bullet image size
            bulletRect.left=bulletPos[0]
            bulletRect.top=bulletPos[1]            
            if bulletRect.colliderect(enemyRect):
                enemys.pop(enemy_index)
                bullets.pop(bullet_index)
            bullet_index+=1               
    # end step 6
        enemy_index+=1

• source code

  Code with step 6

Step 7: Add explosion animation

• prepare images of explosion download all explosion images
• initial explosion before keep_going loop

#7 initial load explosion animation images
explosions=[] # store explosion location and img index [(x,y),i,t] 
explosion_anim=[] #store img for animation
BLACK = (0, 0, 0)
explosion_time=60
for i in range(9):
    filename = 'Explosion0{}.png'.format(i)
    img = pygame.image.load("images/"+ filename).convert()  # convert will create a copy that will draw more quickly on the screen.
    img.set_colorkey(BLACK)
    img= pygame.transform.scale(img, (75, 75))
    explosion_anim.append(img)
    

• add explosion code before display update

    #step 7 plan explosion animation    
    for explosion in explosions:
        if(explosion[1]<9):
            screen.blit(explosion_anim[explosion[1]],explosion[0])
            explosion[2]=explosion[2]-1
            if(explosion[2]<0):     
                explosion[1]=explosion[1]+1
                explosion[2]=explosion_time
                
        else:
            explosions.pop(0) # the first one is always first completed 
    #end step7

• source code

  Code with step 7

Step8: Load sound and play music

• prepare sound and music download sounds

• initial sound and music

  #8 initial load sound
    shooting_sound = pygame.mixer.Sound('sounds/pew.wav')
    pygame.mixer.music.load('sounds/BG.ogg')
    pygame.mixer.music.play(-1) ### makes the gameplay sound in an endless loop
  

• add the sound in the collision check

            if bulletRect.colliderect(enemyRect):
                enemys.pop(enemy_index)
                bullets.pop(bullet_index)

                # step7 play explosion in the location of enemy
                explosions.append([enemyPos,0,explosion_time])

• source code src with step 8

Step9: Draw text for score, life and game over

• initial the score, life

    #initial for step 9
    score=0
    life=3
    game_over=False

• define function for draw text

def draw_text(surf, text, size, x, y):
    ## selecting a cross platform font to display the score
    font = pygame.font.Font(pygame.font.match_font('arial'), size)
    text_surface = font.render(text, True, BLACK)       ## True denotes the font to be anti-aliased 
    text_rect = text_surface.get_rect()
    text_rect.midtop = (x, y)
    surf.blit(text_surface, text_rect)

• draw life and score after load background

screen.blit(background,(0,0))  

#step 9 draw life and score on 
    game_over=life<1 #step9 make game over if life small then 1

    draw_text(screen, "Score: "+str(score), 18, width -100, 10)
    draw_text(screen, "Life: "+str(life), 18, width/2, 10)
    if(game_over):
        draw_text(screen, "Game Over", 50, width/2, height/2 -40)

• add condition on game over

    if(not game_over):
        screen.blit(player, player_pos)
    ...
    ...

• source code

  source code with step9

• final result