main.py

import pygame
import random
import math

#initialise the pygame
pygame.init()

#create the screen
screen = pygame.display.set_mode((800, 600))

#background
#background = pygame.image.load("background.png")
#mixer.music.load("bground.mp3")
#mixer.music.play(-1)

#Title and icon
pygame.display.set_caption("Space Impact")
icon = pygame.image.load("resources/images.png")
pygame.display.set_icon(icon)

#player
playerimg = pygame.image.load("resources/racecar.png")
playerX = 320
playerY = 500
playerX_change = 0

#enemy
enemyimg = []
enemyX = []
enemyY = []
enemyX_change = []
enemyY_change = []
num_of_enemies = 6

for i in range(num_of_enemies):
    enemyimg.append(pygame.image.load("resources/enemy.png"))
    enemyX.append(random.randint(0, 709))
    enemyY.append(random.randint(50,150))
    enemyX_change.append(0.3)
    enemyY_change.append(40) 
 

#bullet
bulletimg = pygame.image.load("resources/bullet.png")
bulletX = 0
bulletY = 500
bulletX_change = 0
bulletY_change = 0.9
bullet_state = "ready"
# Ready  - You cant see the bullet on the screen
# Fire - The bullet is currently moving

#score

score_value = 0
font = pygame.font.Font("resources/PatrickHand-Regular.ttf", 20)

textX = 10
textY = 10

#Game over text
game_over_font = pygame.font.Font("resources/PatrickHand-Regular.ttf", 60)

def show_score(x, y):
    score = font.render("Score: " + str(score_value), True, (0, 0, 0))
    screen.blit(score, (x, y))

def game_over_text():
    over_text = game_over_font.render("GAME OVER !! ", True, (0, 0, 0))
    screen.blit(over_text, (250, 250))

def player(x, y):
    screen.blit(playerimg, (x, y))

def enemy(x, y, i):
    screen.blit(enemyimg[i], (x, y))

def fire_bullet(x, y):
    global bullet_state
    bullet_state = "Fire"
    screen.blit(bulletimg, (x + 30 , y))
def is_collision(enemyX, enemyY, bulletX, bulletY):
    distance = math.sqrt((math.pow(enemyX - bulletX,2)) + (math.pow(enemyY- bulletY, 2)))
    if distance < 40:
        return True
    else:
        return False

# Game loop
running = True
while running:
    #RGB - Red, Green, Blue
    #google colour to RGB 
    screen.fill((255, 255, 255))
     
    #background image
    # screen.blit(backgroung, (0, 0))
    for event in pygame.event.get():
        if event.type == pygame.QUIT: 
            running = False
    # if keystroke check whether its right or left
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT:
                playerX_change = - 0.7
            if event.key == pygame.K_RIGHT:
                playerX_change = + 0.7
            if event.key == pygame.K_SPACE:
                if bullet_state == "ready":
            # Get the current X-co ordinate of the space ship
                    bulletX = playerX
                    fire_bullet(bulletX, bulletY)

        if event.type == pygame.KEYUP:
            if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
                playerX_change = 0

      #checking bounderies 
    playerX += playerX_change

    if playerX <= 0:
        playerX = 0
    elif playerX >= 710:
        playerX = 710

#enemy movement
    for i in range(num_of_enemies):
        #Game over
        if enemyY[i] > 200:
            for j in range(num_of_enemies):
                enemyY[j] = 2000
            game_over_text()
            break
        enemyX[i] += enemyX_change[i]
        if enemyX[i] <= 0:
            enemyX_change[i] = 0.3
            enemyY[i] += enemyY_change[i]
        elif enemyX[i] >= 710:
            enemyX_change[i] = -0.3
            enemyY[i] += enemyY_change[i] 


        # collision
        collision = is_collision(enemyX[i], enemyY[i], bulletX, bulletY)
        if collision:
            bulletY = 480
            bullet_state = "ready"
            score_value += 1
            enemyX[i] = random.randint(0, 709)
            enemyY[i] = random.randint(50,150)

        enemy(enemyX[i], enemyY[i], i)

#bullet movement
    if bulletY <= 0:
        bulletY = 480
        bullet_state = "ready"
    if bullet_state  == "Fire":
        fire_bullet(bulletX, bulletY)
        bulletY -= bulletY_change


    player(playerX, playerY)
    show_score(textX, textY)
    pygame.display.update()