spaceinvader.py

import pygame
from pygame import mixer
from pygame.locals import *
import random

pygame.font.init()
pygame.mixer.pre_init(44100, -16, 2, 512)
mixer.init()


# define fps
clock = pygame.time.Clock()
fps = 60

screen_width = 600
screen_height = 700

screen = pygame.display.set_mode((screen_width, screen_height))
pygame.display.set_caption("Space Invaders")


# define fonts
font30 = pygame.font.SysFont('Constantia', 30)
font40 = pygame.font.SysFont('Constantia', 40)


# load sounds
explosion_fx = pygame.mixer.Sound("audio/explosion.wav")
explosion_fx.set_volume(0.25)

explosion2_fx = pygame.mixer.Sound("audio/explosion2.wav")
explosion2_fx.set_volume(0.25)

laser_fx = pygame.mixer.Sound("audio/laser.wav")
laser_fx.set_volume(0.25)


# define game variables
rows = 5
cols = 5
alien_cooldown = 1000  # bullet cooldown in milliseconds
last_alien_shot = pygame.time.get_ticks()
countdown = 3
last_count = pygame.time.get_ticks()
game_over = 0
# 0 is no game over,1 means player won,-1 means player lost

# define colours
red = (255, 0, 0)
green = (0, 255, 0)
white = (255, 255, 255)


# load images
bg = pygame.image.load("img/bg.png")


def draw_bg():
    screen.blit(bg, (0, 0))


# define function for creating text
def draw_text(text, font, text_col, x, y):
    img = font.render(text, True, text_col)
    screen.blit(img, (x, y))


# create spaceship class
class Spaceship(pygame.sprite.Sprite):
    def __init__(self, x, y, health):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.image.load("img/spaceship.png")
        self.rect = self.image.get_rect()
        self.rect.center = [x, y]
        self.health_start = health
        self.health_remaining = health
        self.last_shot = pygame.time.get_ticks()

    def update(self):
        # set movement speed
        speed = 5
        # set a cooldown variable
        cooldown = 400  # milliseconds
        game_over = 0

        # get key presses
        key = pygame.key.get_pressed()
        if key[pygame.K_LEFT] and self.rect.left > 0:
            self.rect.x -= speed
        if key[pygame.K_RIGHT] and self.rect.right < screen_width:
            self.rect.x += speed

        # record current time
        time_now = pygame.time.get_ticks()

        # shoot
        if key[pygame.K_SPACE] == True and self.shot == False and time_now - self.last_shot > cooldown:
            laser_fx.play()
            bullet = Bullet(self.rect.centerx, self.rect.top)
            self.shot = True
            bullet_group.add(bullet)
            self.last_shot = time_now
        if key[pygame.K_SPACE] == False:
            self.shot = False
        # update mask{mask contains the img without the rect but with boundary of img that is all parts without transparency}
        self.mask = pygame.mask.from_surface(self.image)

        # draw health bar
        pygame.draw.rect(
            screen, red, (self.rect.x, (self.rect.bottom + 10),
                          self.rect.width, 12)
        )
        if self.health_remaining > 0:
            pygame.draw.rect(
                screen,
                green,
                (
                    self.rect.x,
                    (self.rect.bottom + 10),
                    int(self.rect.width * (self.health_remaining / self.health_start)),
                    12,
                ),
            )
        elif self.health_remaining <= 0:
            explosion = Explosion(self.rect.centerx, self.rect.centery, 3)
            explosion_group.add(explosion)
            self.kill()
            game_over = -1
        return game_over


# create bullets class
class Bullet(pygame.sprite.Sprite):
    def __init__(self, x, y):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.image.load("img/bullet.png")
        self.rect = self.image.get_rect()
        self.rect.center = [x, y]

    def update(self):
        self.rect.y -= 5  # speed of bullet
        if self.rect.bottom < 0:
            self.kill()
        if pygame.sprite.spritecollide(self, alien_group, True):
            self.kill()
            explosion_fx.play()
            explosion = Explosion(self.rect.centerx, self.rect.centery, 2)
            explosion_group.add(explosion)


# create aliens class
class Aliens(pygame.sprite.Sprite):
    def __init__(self, x, y):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.image.load(
            "img/alien" + str(random.randint(1, 5)) + ".png")
        self.rect = self.image.get_rect()
        self.rect.center = [x, y]
        self.move_direction = 1
        self.move_counter = 0

    def update(self):
        self.rect.x += self.move_direction
        self.move_counter += 1
        if abs(self.move_counter) > 75:
            self.move_direction *= -1
            self.move_counter *= self.move_direction


# create alien bullets class
class Alien_Bullet(pygame.sprite.Sprite):
    def __init__(self, x, y):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.image.load("img/alien_bullet.png")
        self.rect = self.image.get_rect()
        self.rect.center = [x, y]

    def update(self):
        self.rect.y += 2  # speed of bullet
        if self.rect.top > screen_height:
            self.kill()
        if pygame.sprite.spritecollide(
            self, spaceship_group, False, pygame.sprite.collide_mask
        ):
            self.kill()
            explosion2_fx.play()
            # reduce spaceship health
            spaceship.health_remaining -= 1
            explosion = Explosion(self.rect.centerx, self.rect.centery, 1)
            explosion_group.add(explosion)


# create explosion class
class Explosion(pygame.sprite.Sprite):
    def __init__(self, x, y, size):
        pygame.sprite.Sprite.__init__(self)
        self.images = []
        for num in range(1, 6):
            img = pygame.image.load(f"img/exp{num}.png")
            if size == 1:
                img = pygame.transform.scale(img, (20, 20))
            if size == 2:
                img = pygame.transform.scale(img, (40, 40))
            if size == 3:
                img = pygame.transform.scale(img, (160, 160))
            # add image to the list
            self.images.append(img)
        self.index = 0
        self.image = self.images[self.index]
        self.rect = self.image.get_rect()
        self.rect.center = [x, y]
        self.counter = 0

    def update(self):
        explosion_speed = 3
        # update explosion animation
        self.counter += 1

        if self.counter >= explosion_speed and self.index < len(self.images)-1:
            self.counter = 0
            self.index += 1
            self.image = self.images[self.index]

        # if the animation is complete,delete explosion
        if self.index >= len(self.images)-1 and self.counter >= explosion_speed:
            self.kill()


# create sprite groups
spaceship_group = pygame.sprite.Group()
bullet_group = pygame.sprite.Group()
alien_group = pygame.sprite.Group()
alien_bullet_group = pygame.sprite.Group()
explosion_group = pygame.sprite.Group()


def create_aliens():
    for row in range(rows):
        for items in range(cols):
            alien = Aliens(100 + items * 100, 100 + row * 70)
            alien_group.add(alien)


create_aliens()


# create player{3 bullet shots before spaceship dies}
spaceship = Spaceship(int(screen_width / 2), screen_height - 100, 3)
spaceship_group.add(spaceship)


run = True
while run:

    clock.tick(fps)

    # draw background
    draw_bg()

    if countdown == 0:
        # create random alien bullets
        # record current time
        time_now = pygame.time.get_ticks()
        # shoot {initially last alien shot is 0}
        if (
            time_now - last_alien_shot > alien_cooldown
            and len(alien_bullet_group) < 5
            and len(alien_group) > 0
        ) and game_over == 0:
            attacking_alien = random.choice(alien_group.sprites())
            alien_bullet = Alien_Bullet(
                attacking_alien.rect.centerx, attacking_alien.rect.bottom
            )
            alien_bullet_group.add(alien_bullet)
            last_alien_shot = time_now

        # check if all the aliens have been destroyed
        if len(alien_group) == 0:
            game_over = 1

        if game_over == 0:
            # update spaceship
            game_over = spaceship.update()

            # update sprite groups
            bullet_group.update()
            alien_group.update()
            alien_bullet_group.update()
        else:
            if game_over == -1:
                draw_text('GAME OVER!', font40, white, int(
                    screen_width/2-100), int(screen_height/2+80))
            if game_over == 1:
                draw_text('YOU WON!', font40, white, int(
                    screen_width/2-100), int(screen_height/2+80))

    if countdown > 0:
        draw_text('GET READY!', font40, white, int(
            screen_width/2-110), int(screen_height/2+80))
        draw_text(str(countdown), font30, white, int(
            screen_width/2-10), int(screen_height/2+130))
        count_timer = pygame.time.get_ticks()
        if count_timer-last_count > 1000:  # 1sec has passed
            countdown -= 1
            last_count = count_timer

    # update explosion group
    explosion_group.update()

    # draw sprite groups
    spaceship_group.draw(screen)
    bullet_group.draw(screen)
    alien_group.draw(screen)
    alien_bullet_group.draw(screen)
    explosion_group.draw(screen)

    # event handlers
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False

    pygame.display.update()


pygame.quit()