AlienInvasion | Demo Game for Mobile HTML5 Game Development | Game Engine library

import sys
import pygame
from pygame.sprite import Sprite

class Settings:

    def __init__(self):
        self.screen_width = 1200
        self.screen_height = 800
        self.bg_color = (230, 230, 230)

        self.ship_speed = 1.5 

        self.bullet_speed = 1.0
        self.bullet_width = 3
        self.bullet_height = 15
        self.bullet_color = (60,60,60)

        self.bullets_allowed = 3

class Ship:

    def __init__(self, ai_game):
        self.screen = ai_game.screen

        self.settings = ai_game.settings

        self.screen_rect = ai_game.screen.get_rect()

        self.image = pygame.image.load('images/ship.bmp')
        self.rect = self.image.get_rect()

        self.rect.midbottom = self.screen_rect.midbottom

        self.x = float(self.rect.x) 

        self.moving_right = False
        self.moving_left = False


    def update(self):

        if self.moving_right and self.rect.right < self.screen_rect.right:
            self.x += self.settings.ship_speed
        if self.moving_left and self.rect.left > 0:
            self.x -= self.settings.ship_speed
        
        self.rect.x = self.x
            


    def blitme(self):
        self.screen.blit(self.image, self.rect)
    

class Bullet(Sprite):

    def __init__(self, ai_game):
        super().__init__()
        self.screen = ai_game.screen
        self.settings = ai_game.settings
        self.color = self.settings.bullet_color
        self.rect = pygame.Rect(0, 0, self.settings.bullet_width, self.settings.bullet_height)
        self.rect.midtop = ai_game.ship.rect.midtop
        self.y = float(self.rect.y)

    def update(self):

        self.y -= self.settings.bullet_speed
        self.rect.y = self.y

    def draw_bullet(self):
        pygame.draw.rect(self.screen, self.color, self.rect)

class Alien(Sprite):

    def __init__(self, ai_game):
        super().__init__()

        self.screen = ai_game.screen

        self.image = pygame.image.load('images/alien.bmp')
        self.rect = self.image.get_rect()

        self.rect.x = self.rect.width
        self.rect.y = self.rect.height

        self.x = float(self.rect.x)         



           
class AlienInvasion:

    def __init__(self):
        pygame.init()
        self.settings = Settings()
        self.screen = pygame.display.set_mode((self.settings.screen_width, self.settings.screen_height))
        pygame.display.set_caption("Alien Invasion")
        self.ship = Ship(self)
        self.bullets = pygame.sprite.Group()
        self.aliens = pygame.sprite.Group()


    def run_game(self):
        while True:
            self._check_events()
            self._update_screen()
            self._update_bullets()
            self._create_fleet()


    def _check_events(self):
        for event in pygame.event.get():
            if event.type == pygame.KEYDOWN:
                self._check_keydown_events(event)
            elif event.type == pygame.KEYUP:
                self._check_keyup_events(event)    
            elif event.type == pygame.QUIT:
                sys.exit()

    def _check_keydown_events(self, event):
        if event.key == pygame.K_RIGHT:
            self.ship.moving_right = True
        elif event.key == pygame.K_LEFT:
            self.ship.moving_left = True   
        elif event.key == pygame.K_SPACE:
            self._fire_bullet()
        elif event.key == pygame.K_q:
            sys.exit()        

    def _check_keyup_events(self, event):
        if event.key == pygame.K_RIGHT:
            self.ship.moving_right = False
        elif event.key == pygame.K_LEFT:
            self.ship.moving_left = False    

    def _fire_bullet(self):
        if len(self.bullets) <= self.settings.bullets_allowed:
            bullet = Bullet(self)
            self.bullets.add(bullet)

    def _update_bullets(self):
        self.bullets.update()

        for bullet in self.bullets.copy():
            if bullet.rect.bottom <= 0:
                self.bullets.remove(bullet)

    def _create_fleet(self):
        alien = Alien(self)
        self.aliens.add(alien)

    def _update_screen(self):
        self.screen.fill(self.settings.bg_color)
        self.ship.blitme()
        for bullet in self.bullets.sprites():
            bullet.draw_bullet()
        self.aliens.draw(self.screen)    
        pygame.display.flip() 


if __name__ == '__main__':

    ai = AlienInvasion()

    ai.run_game()