Python外星人入侵背景颜色 python项目外星人入侵

创建第一个外星人

创建Alien 类

alien.py

import pygame
from pygame.sprite import Sprite
class Alien(Sprite):
    """表示单个外星人的类"""
    def __init__(self, ai_settings, screen):
        """初始化外星人并设置其起始位置"""
        super(Alien, self).__init__()
        self.screen = screen
        self.ai_settings = ai_settings
        # 加载外星人图像，并设置其rect属性
        self.image = pygame.image.load('images/alien.bmp')
        self.rect = self.image.get_rect()
        # 每个外星人最初都在屏幕左上角附近
        self.rect.x = self.rect.width
        self.rect.y = self.rect.height
        # 存储外星人的准确位置
        self.x = float(self.rect.x)

    def blitme(self):
        """在指定位置绘制外星人"""
        self.screen.blit(self.image, self.rect)

创建 Alien 实例

下面在alien_invasion.py中创建一个Alien 实例：
alien_invasion.py

import sys
import pygame
from settings import Settings
from ship import Ship
from alien import Alien
import game_functions as gf
from pygame.sprite import Group

def run_game():
    # 初始化游戏并创建一个屏幕对象
    pygame.init()
    ai_settings = Settings()
    screen = pygame.display.set_mode((ai_settings.screen_width, ai_settings.screen_height))
    pygame.display.set_caption("Alien Invasion")
    # 创建一艘飞船
    ship = Ship(ai_settings, screen)
    bullets = Group()
    # 创建一个外星人
    alien = Alien(ai_settings, screen)
    while True:
        gf.check_events(ai_settings, screen, ship, bullets)
        ship.update()
        gf.update_bullets(bullets)
        gf.update_screen(ai_settings, screen, ship, alien, bullets)
run_game()

让外星人出现在屏幕上

为让外星人出现在屏幕上，我们在update_screen() 中调用其方法blitme() ：game_functions.py

def update_screen(ai_settings, screen, ship, alien, bullets): 
	--snip-- 
	# 在飞船和外星人后面重绘所有的子弹 
	for bullet in bullets: 
		bullet.draw_bullet() 
	ship.blitme() 
	alien.blitme() 
	# 让最近绘制的屏幕可见 
	pygame.display.flip()

创建一群外星人

创建多行外星人

为创建一行外星人，首先在alien_invasion.py中创建一个名为aliens 的空编组，用于存储全部外星人，再调用game_functions.py中创建外星人群的函数：
alien_invasion.py

import sys
import pygame
from settings import Settings
from ship import Ship
from alien import Alien
import game_functions as gf
from pygame.sprite import Group

def run_game():
    # 初始化游戏并创建一个屏幕对象
    pygame.init()
    ai_settings = Settings()
    screen = pygame.display.set_mode((ai_settings.screen_width, ai_settings.screen_height))
    pygame.display.set_caption("Alien Invasion")
    # 创建一艘飞船
    ship = Ship(ai_settings, screen)
    bullets = Group()
    aliens = Group()
    # 创建外星人群
    gf.create_fleet(ai_settings, screen, aliens)
    while True:
        gf.check_events(ai_settings, screen, ship, bullets)
        ship.update()
        gf.update_bullets(bullets)
        gf.update_screen(ai_settings, screen, ship, aliens, bullets)
run_game()

game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien

def check_keydown_events(event, ai_settings, screen, ship, bullets):
    """响应按键"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        ship.moving_left = True
    elif event.key == pygame.K_SPACE:
        fire_bullet(ai_settings, screen, ship, bullets)
    elif event.key == pygame.K_q:
        sys.exit()

def fire_bullet(ai_settings, screen, ship, bullets):
    """如果还没有到达限制，就发射一颗子弹"""
    # 创建新子弹，并将其加入到编组bullets中
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)

def check_keyup_events(event, ship):
    """响应松开"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = False
    elif event.key == pygame.K_LEFT:
        ship.moving_left = False

def check_events(ai_settings, screen, ship, bullets):
    """响应按键和鼠标事件"""
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type == pygame.KEYDOWN:
            check_keydown_events(event, ai_settings, screen, ship, bullets)
        elif event.type == pygame.KEYUP:
            check_keyup_events(event, ship)

def update_screen(ai_settings, screen, ship, aliens, bullets):
    """更新屏幕上的图像，并切换到新屏幕"""
    # 每次循环时都重绘屏幕
    screen.fill(ai_settings.bg_color)
    for bullet in bullets.sprites():
        bullet.draw_bullet()
    ship.blitme()
    aliens.draw(screen)
    # 让最近绘制的屏幕可见
    pygame.display.flip()

def update_bullets(bullets):
    """更新子弹的位置，并删除已消失的子弹"""
    # 更新子弹的位置
    bullets.update()
    # 删除已消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet)

def create_fleet(ai_settings, screen, aliens):
    """创建外星人群"""
    # 创建一个外星人，并计算一行可容纳多少个外星人
    # 外星人间距为外星人宽度
    alien = Alien(ai_settings, screen)
    alien_width = alien.rect.width
    available_space_x = ai_settings.screen_width - 2 * alien_width
    number_aliens_x = int(available_space_x / (2 * alien_width))
    # 创建第一行外星人
    for alien_number in range(number_aliens_x):
        # 创建一个外星人并将其加入当前行
        alien = Alien(ai_settings, screen)
        alien.x = alien_width + 2 * alien_width * alien_number
        alien.rect.x = alien.x
        aliens.add(alien)

运行结果如下：

重构 create_fleet()

倘若我们创建了外星人群，也许应该让create_fleet() 保持原样，但鉴于创建外星人的工作还未完成，我们稍微清理一下这个函数。下面是create_fleet() 和两个新函数，get_number_aliens_x() 和create_alien()

game_functions.py

def get_number_aliens_x(ai_settings, alien_width):
    """计算每行可容纳多少个外星人"""
    available_space_x = ai_settings.screen_width - 2 * alien_width
    number_aliens_x = int(available_space_x / (2 * alien_width))
    return number_aliens_x

def create_alien(ai_settings, screen, aliens, alien_number):
    """创建一个外星人并将其放在当前行"""
    alien = Alien(ai_settings, screen)
    alien_width = alien.rect.width
    alien.x = alien_width + 2 * alien_width * alien_number
    alien.rect.x = alien.x
    aliens.add(alien)

def create_fleet(ai_settings, screen, aliens):
    """创建外星人群"""
    # 创建一个外星人，并计算每行可容纳多少个外星人
    alien = Alien(ai_settings, screen)
    number_aliens_x = get_number_aliens_x(ai_settings, alien.rect.width)
    # 创建第一行外星人
    for alien_number in range(number_aliens_x):
        create_alien(ai_settings, screen, aliens, alien_number)

添加行

要创建外星人群，需要计算屏幕可容纳多少行，并对创建一行外星人的循环重复相应的次数。为计算可容纳的行数，我们这样计算可用垂直空间：将屏幕高度减去第一行外星人 的上边距（外星人高度）、飞船的高度以及最初外星人群与飞船的距离（外星人高度的两倍）。
每行下方都要留出一定的空白区域，并将其设置为外星人的高度。为计算可容纳的行数，我们将可用垂直空间除以外星人高度的两倍（同样，如果这样的计算不对，我们马上就能发现，继而将间距调整为合理的值）。
知道可容纳多少行后，便可重复执行创建一行外星人的代码：
game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien

def check_keydown_events(event, ai_settings, screen, ship, bullets):
    """响应按键"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        ship.moving_left = True
    elif event.key == pygame.K_SPACE:
        fire_bullet(ai_settings, screen, ship, bullets)
    elif event.key == pygame.K_q:
        sys.exit()

def fire_bullet(ai_settings, screen, ship, bullets):
    """如果还没有到达限制，就发射一颗子弹"""
    # 创建新子弹，并将其加入到编组bullets中
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)

def check_keyup_events(event, ship):
    """响应松开"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = False
    elif event.key == pygame.K_LEFT:
        ship.moving_left = False

def check_events(ai_settings, screen, ship, bullets):
    """响应按键和鼠标事件"""
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type == pygame.KEYDOWN:
            check_keydown_events(event, ai_settings, screen, ship, bullets)
        elif event.type == pygame.KEYUP:
            check_keyup_events(event, ship)

def update_screen(ai_settings, screen, ship, aliens, bullets):
    """更新屏幕上的图像，并切换到新屏幕"""
    # 每次循环时都重绘屏幕
    screen.fill(ai_settings.bg_color)
    for bullet in bullets.sprites():
        bullet.draw_bullet()
    ship.blitme()
    aliens.draw(screen)
    # 让最近绘制的屏幕可见
    pygame.display.flip()

def update_bullets(bullets):
    """更新子弹的位置，并删除已消失的子弹"""
    # 更新子弹的位置
    bullets.update()
    # 删除已消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet)

def get_number_aliens_x(ai_settings, alien_width):
    """计算每行可容纳多少个外星人"""
    available_space_x = ai_settings.screen_width - 2 * alien_width
    number_aliens_x = int(available_space_x / (2 * alien_width))
    return number_aliens_x

def get_number_rows(ai_settings, ship_height, alien_height):
    """计算屏幕可容纳多少行外星人"""
    available_space_y = (ai_settings.screen_height - (3 * alien_height) - ship_height)
    number_rows = int(available_space_y / (2 * alien_height))
    return number_rows

def create_alien(ai_settings, screen, aliens, alien_number, row_number):
    """创建一个外星人并将其放在当前行"""
    alien = Alien(ai_settings, screen)
    alien_width = alien.rect.width
    alien.x = alien_width + 2 * alien_width * alien_number
    alien.rect.x = alien.x
    alien.rect.y = alien.rect.height + 2 * alien.rect.height * row_number
    aliens.add(alien)

def create_fleet(ai_settings, screen, ship, aliens):
    """创建外星人群"""
    alien = Alien(ai_settings, screen)
    number_aliens_x = get_number_aliens_x(ai_settings, alien.rect.width)
    number_rows = get_number_rows(ai_settings, ship.rect.height, alien.rect.height)
    # 创建外星人群
    for row_number in range(number_rows):
        for alien_number in range(number_aliens_x):
            create_alien(ai_settings, screen, aliens, alien_number, row_number)

alien_invasion.py

import sys
import pygame
from settings import Settings
from ship import Ship
from alien import Alien
import game_functions as gf
from pygame.sprite import Group

def run_game():
    # 初始化游戏并创建一个屏幕对象
    pygame.init()
    ai_settings = Settings()
    screen = pygame.display.set_mode((ai_settings.screen_width, ai_settings.screen_height))
    pygame.display.set_caption("Alien Invasion")
    # 创建一艘飞船
    ship = Ship(ai_settings, screen)
    bullets = Group()
    aliens = Group()
    # 创建外星人群
    gf.create_fleet(ai_settings, screen, ship, aliens)
    while True:
        gf.check_events(ai_settings, screen, ship, bullets)
        ship.update()
        gf.update_bullets(bullets)
        gf.update_screen(ai_settings, screen, ship, aliens, bullets)
run_game()

运行结果如下：