计分和游戏控制

我们在玩游戏时，都有计分的制度，随着分数的增长，玩家玩游戏的精神也在增长，哈哈。
并且游戏都有一个控制按钮，比如开始，或者结束。

1.添加Play按钮

我们先让游戏一开始处于非活动状态，并提示玩家单击Play按钮来开始游戏。为此，在game_stats.py中添加代码：
game_stats.py

class GameStats():"""跟踪游戏的统计信息"""def __init__(self,ai_settings):"""初始化统计信息"""self.ai_settings = ai_settingsself.reset_stats()#游戏刚开始处于非活动状态self.game_active = Falsedef reset_stats(self):"""初始化在游戏运行期间可能变化的统计信息"""self.ships_left = self.ai_settings.ship_limit

1.1 创建Button类

由于Pygame没有内置创建按钮的方法，我们创建一个Button类，用于创建带标签的实心矩形，可以使用这些代码来创建任何按钮。我们保存文件名为button.py

import pygame.font #导入模块pygame.font，它让Pygame能够将文本渲染到屏幕上class Button():def __init__(self,ai_settings,screen,msg):"""初始化按钮的属性"""self.screen = screenself.screen_rect = screen.get_rect()#设置按钮的尺寸和其他属性self.width,self.height = 200, 50self.button_color = (0,255,0)self.text_color = (255,255,255)self.font = pygame.font.SysFont(None,48)#我们使用字体来渲染渲染文本，实参None让Pygame使用默认字体，而48指定了文本的字号#创建按钮的rect对象，并使其居中self.rect = pygame.Rect(0,0,self.width,self.height)self.rect.center = self.screen_rect.center#按钮的标签只需创建一次self.prep_msg(msg)#Pygame通过将你要显示的字符串渲染为图像来处理文本

然后完成prep_msg的代码：
button.py

import pygame.fontclass Button():def __init__(self,ai_settings,screen,msg):"""初始化按钮的属性"""self.screen = screenself.screen_rect = screen.get_rect()#设置按钮的尺寸和其他属性self.width,self.height = 200, 50self.button_color = (0,255,0)self.text_color = (255,255,255)self.font = pygame.font.SysFont(None,48)#创建按钮的rect对象，并使其居中self.rect = pygame.Rect(0,0,self.width,self.height)self.rect.center = self.screen_rect.center#按钮的标签只需创建一次self.prep_msg(msg)def prep_msg(self,msg):"""将msg渲染为图像，并使其在按钮上居中"""#msg 要渲染为图像的文本#font.render()将存储在msg中的文本转换为图像，然后存储在msg_image中，第二个实参指定是否开启反锯齿功能#反锯齿功能：让文本的边缘更平滑self.msg_image = self.font.render(msg,True,self.text_color,self.button_color)self.msg_image_rect = self.msg_image.get_rect()self.msg_image_rect.center = self.rect.center

最后我们创建方法draw_button()，通过调用它来将按钮显示到屏幕上：
button.py

import pygame.fontclass Button():def __init__(self,ai_settings,screen,msg):"""初始化按钮的属性"""self.screen = screenself.screen_rect = screen.get_rect()#设置按钮的尺寸和其他属性self.width,self.height = 200, 50self.button_color = (0,255,0)self.text_color = (255,255,255)self.font = pygame.font.SysFont(None,48)#创建按钮的rect对象，并使其居中self.rect = pygame.Rect(0,0,self.width,self.height)self.rect.center = self.screen_rect.center#按钮的标签只需创建一次self.prep_msg(msg)def prep_msg(self,msg):"""将msg渲染为图像，并使其在按钮上居中"""#msg 要渲染为图像的文本#font.render()将存储在msg中的文本转换为图像，然后存储在msg_image中，第二个实参指定是否开启反锯齿功能#反锯齿功能：让文本的边缘更平滑self.msg_image = self.font.render(msg,True,self.text_color,self.button_color)self.msg_image_rect = self.msg_image.get_rect()self.msg_image_rect.center = self.rect.centerdef draw_button(self):#绘制一个用颜色填充的按钮，在绘制文本self.screen.fill(self.button_color,self.rect)  #h绘制按钮的矩形self.screen.blit(self.msg_image,self.msg_image_rect) #传递一幅图像与该图像关联的rect对象

1.2 在屏幕上绘制按钮

接下来我们就是用button类来创建一个play按钮，在alien_invasion.py中直接创建

import pygame
from settings import Settings
from game_stats import GameStats
from ship import Ship
from alien import Alien
import game_functions as gf
from pygame.sprite import Group
from button import Button  #导入button类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Play按钮,并创建一个button实例play_button = Button(ai_settings,screen,"play") #创建一个外星人alien = Alien(ai_settings,screen)#创建一个用于存储游戏统计信息的实例stats = GameStats(ai_settings)#创建一艘非飞船ship = Ship(ai_settings,screen)#创建一个用于存储子弹的编组bullets = Group()aliens = Group()#创建外星人群gf.create_fleet(ai_settings,screen,ship,aliens)#开始游戏的主循环while True:sys.pause()#监视键盘和鼠标事件gf.check_events(ai_settings,screen,ship,bullets)if stats.game_active:ship.update()gf.update_bullets(ai_settings,screen,ship,aliens,bullets)gf.update_aliens(ai_settings,stats,screen,ship,aliens,bullets)gf.update_screen(ai_settings,screen,stats,ship,bullets,aliens,play_button)run_game()

接下来需要修改update_screen方法。
game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)def check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef 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(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？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,stats,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if len(aliens) == 0:#删除现有的子弹并新建一群外星人bullets.empty()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,ship,aliens):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):print("Ship hit!!!")def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)sys.exit(0)else:stats.game_active = Falsedef check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)

1.3 开始游戏

现在屏幕上面已经有了，play按钮，但当点击play按钮开始游戏，还需添加一些代码，以监视与这个按钮相关的鼠标事件：
game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)def check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen, stats, play_button,ship,bullets):"""响应按键和鼠标事件"""for event in pygame.event.get():if event.type == pygame.QUIT:sys.exit(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？elif event.type == pygame.KEYDOWN:check_keydown_events(event, ai_settings,screen,ship, bullets)elif event.type == pygame.KEYUP:check_keyup_events(event,ship)elif event.type == pygame.MOUSEBUTTONDOWN:mouse_x, mouse_y = pygame.mouse.get_pos()check_play_button(stats,play_button,mouse_x,mouse_y)def check_play_button(stats,play_button,mouse_x,mouse_y):"""在玩家单击Play按钮时开始游戏"""if play_button.rect.collidepoint(mouse_x,mouse_y):stats.game_active = Truedef update_screen(ai_settings,screen,stats,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if len(aliens) == 0:#删除现有的子弹并新建一群外星人bullets.empty()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,ship,aliens):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):print("Ship hit!!!")def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)sys.exit(0)else:stats.game_active = Falsedef check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)

alien_invasion.py

import pygame
from settings import Settings
from game_stats import GameStats
from ship import Ship
from alien import Alien
import game_functions as gf
from pygame.sprite import Group
from button import Button  #导入button类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Play按钮,并创建一个button实例play_button = Button(ai_settings,screen,"play") #创建一个外星人alien = Alien(ai_settings,screen)#创建一个用于存储游戏统计信息的实例stats = GameStats(ai_settings)#创建一艘非飞船ship = Ship(ai_settings,screen)#创建一个用于存储子弹的编组bullets = Group()aliens = Group()#创建外星人群gf.create_fleet(ai_settings,screen,ship,aliens)#开始游戏的主循环while True:#   sys.pause()#监视键盘和鼠标事件gf.check_events(ai_settings,screen,stats,play_button,ship,bullets)if stats.game_active:ship.update()gf.update_bullets(ai_settings,screen,ship,aliens,bullets)gf.update_aliens(ai_settings,stats,screen,ship,aliens,bullets)gf.update_screen(ai_settings,screen,stats,ship,bullets,aliens,play_button)run_game()

1.4 重置游戏

前面编写的代码只处理了玩家第一次单击Play按钮的情况，而没有处理游戏结束的情况，因为没有重置导致游戏结束的条件。
为在玩家每次单击Play按钮时都重置游戏，需要重置统计信息，删除现有的外星人和子弹，创建一群新的外星人，并让飞船居中。
game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)def check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen, stats, play_button,ship,aliens,bullets):"""响应按键和鼠标事件"""for event in pygame.event.get():if event.type == pygame.QUIT:sys.exit(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？elif event.type == pygame.KEYDOWN:check_keydown_events(event, ai_settings,screen,ship, bullets)elif event.type == pygame.KEYUP:check_keyup_events(event,ship)elif event.type == pygame.MOUSEBUTTONDOWN:mouse_x, mouse_y = pygame.mouse.get_pos()check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y)def check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y):"""在玩家单击Play按钮时开始游戏"""if play_button.rect.collidepoint(mouse_x,mouse_y):#重置游戏统计信息stats.reset_status()stats.game_active = True#清空外星人列表和子弹列表aliens.empty()bullets.empty()#创建一群新的外星人，并让飞船居中create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()def update_screen(ai_settings,screen,stats,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if len(aliens) == 0:#删除现有的子弹并新建一群外星人bullets.empty()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,ship,aliens):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):print("Ship hit!!!")def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)sys.exit(0)else:stats.game_active = Falsedef check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)

alien_invasion.py

import pygame
from settings import Settings
from game_stats import GameStats
from ship import Ship
from alien import Alien
import game_functions as gf
from pygame.sprite import Group
from button import Button  #导入button类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Play按钮,并创建一个button实例play_button = Button(ai_settings,screen,"play") #创建一个外星人alien = Alien(ai_settings,screen)#创建一个用于存储游戏统计信息的实例stats = GameStats(ai_settings)#创建一艘非飞船ship = Ship(ai_settings,screen)#创建一个用于存储子弹的编组bullets = Group()aliens = Group()#创建外星人群gf.create_fleet(ai_settings,screen,ship,aliens)#开始游戏的主循环while True:#   sys.pause()#监视键盘和鼠标事件gf.check_events(ai_settings,screen,stats,play_button,ship,aliens,bullets)if stats.game_active:ship.update()gf.update_bullets(ai_settings,screen,ship,aliens,bullets)gf.update_aliens(ai_settings,stats,screen,ship,aliens,bullets)gf.update_screen(ai_settings,screen,stats,ship,bullets,aliens,play_button)run_game()

1.5 将Play按钮切换到非活动状态

当前的play按钮存在一个问题，那就是即便Play按钮不可见，玩家单击其原来所在区域时，游戏依然会做出响应。游戏开始后，如果玩家不小心单击了Play按钮原来所处的区域，游戏将重新开始。
那怎么修改这个bug呢？我们让游戏在game_active为False时才开始：
game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)def check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen, stats, play_button,ship,aliens,bullets):"""响应按键和鼠标事件"""for event in pygame.event.get():if event.type == pygame.QUIT:sys.exit(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？elif event.type == pygame.KEYDOWN:check_keydown_events(event, ai_settings,screen,ship, bullets)elif event.type == pygame.KEYUP:check_keyup_events(event,ship)elif event.type == pygame.MOUSEBUTTONDOWN:mouse_x, mouse_y = pygame.mouse.get_pos()check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y)def check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y):"""在玩家单击Play按钮时开始游戏"""button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)if button_clicked and not stats.game_active:#隐藏光标pygame.mouse.set_visible(False)#重置游戏统计信息stats.reset_stats()stats.game_active = True#清空外星人列表和子弹列表aliens.empty()bullets.empty()#创建一群新的外星人，并让飞船居中create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()def update_screen(ai_settings,screen,stats,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if len(aliens) == 0:#删除现有的子弹并新建一群外星人bullets.empty()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,ship,aliens):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):print("Ship hit!!!")def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)sys.exit(0)else:stats.game_active = Falsedef check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)

2. 提高等级

下面为游戏添加点有趣的玩法：每当玩家将屏幕上的外星人都消灭干净后，加快游戏的节奏，让游戏玩起来更难。

2.1 修改速度设置

我们首先需要重新组织settings类，将游戏设置划分成静态的和动态的两组。对于随着游戏进行而变化的设置，我们还确保它们在开始新游戏时被重置。
settings.py

class Settings():"""存储<<外星人入侵>>的所有设置的类"""def __init__(self):"""初始化游戏的设置"""#屏幕设置self.screen_width = 800self.screen_height = 600self.bg_color = (230,230,230)#飞船的设置self.ship_speed_factor = 1.5self.ship_limit = 3#子弹设置self.bullet_speed_factor = 3self.bullet_width = 3self.bullet_height = 15self.bullet_color = (60 , 60 , 60)self.bullets_allowed = 5   #将在屏幕内可以存在的子弹限制为3颗#外星人设置self.alien_speed_factor = 1self.fleet_drop_speed = 10#以什么样的速度加快游戏节奏self.speedup_scale = 1.1self.initialize_dynamic_settings()def initialize_dynamic_settings(self):"""初始化随游戏进行而变化的设置"""#该方法设置了飞船、子弹和外星人的初始速度self.ship_speed_factor = 1.5self.bullet_speed_factor = 3self.alien_speed_factor = 1#fleet_direction为1表示向右移，为-1表示向左移self.fleet_direction = 1def increase_speed(self):"""提高速度设置"""#使用该方法在玩家提高一个等级时，来提高飞船、子弹和外星人的速度self.ship_speed_factor *= self.speedup_scaleself.bullet_speed_factor *= self.speedup_scaleself.alien_speed_factor *=self.speedup_scale

game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)def check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen, stats, play_button,ship,aliens,bullets):"""响应按键和鼠标事件"""for event in pygame.event.get():if event.type == pygame.QUIT:sys.exit(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？elif event.type == pygame.KEYDOWN:check_keydown_events(event, ai_settings,screen,ship, bullets)elif event.type == pygame.KEYUP:check_keyup_events(event,ship)elif event.type == pygame.MOUSEBUTTONDOWN:mouse_x, mouse_y = pygame.mouse.get_pos()check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y)def check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y):"""在玩家单击Play按钮时开始游戏"""button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)if button_clicked and not stats.game_active:#隐藏光标pygame.mouse.set_visible(False)#重置游戏统计信息stats.reset_stats()stats.game_active = True#清空外星人列表和子弹列表aliens.empty()bullets.empty()#创建一群新的外星人，并让飞船居中create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()def update_screen(ai_settings,screen,stats,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if len(aliens) == 0:#删除现有的子弹并新建一群外星人#删除现有的子弹，加快游戏节奏，并创建一群新的外星人bullets.empty()ai_settings.increase_speed()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,ship,aliens):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):print("Ship hit!!!")def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)sys.exit(0)else:stats.game_active = Falsepygame.mouse.set_visible(True)def check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)

2.2 重置速度

每当玩家开始新游戏时，都需要将发生了变化的设置重置为初始值，否则新游戏开始时，速度设置将是前一次游戏增加了的值：
game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)def check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen, stats, play_button,ship,aliens,bullets):"""响应按键和鼠标事件"""for event in pygame.event.get():if event.type == pygame.QUIT:sys.exit(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？elif event.type == pygame.KEYDOWN:check_keydown_events(event, ai_settings,screen,ship, bullets)elif event.type == pygame.KEYUP:check_keyup_events(event,ship)elif event.type == pygame.MOUSEBUTTONDOWN:mouse_x, mouse_y = pygame.mouse.get_pos()check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y)def check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y):"""在玩家单击Play按钮时开始游戏"""button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)if button_clicked and not stats.game_active:#重置游戏设置ai_settings.initialize_dynamic_settings()#隐藏光标pygame.mouse.set_visible(False)#重置游戏统计信息stats.reset_stats()stats.game_active = True#清空外星人列表和子弹列表aliens.empty()bullets.empty()#创建一群新的外星人，并让飞船居中create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()def update_screen(ai_settings,screen,stats,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if len(aliens) == 0:#删除现有的子弹并新建一群外星人#删除现有的子弹，加快游戏节奏，并创建一群新的外星人bullets.empty()ai_settings.increase_speed()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,ship,aliens):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):print("Ship hit!!!")def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)sys.exit(0)else:stats.game_active = Falsepygame.mouse.set_visible(True)def check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)

然后我们运行程序后，就会发现，随着消灭的外星人越多，游戏的节奏越来越快，也越来越紧张…

3 记分

下面为游戏添加一个计分系统，来实时地跟踪玩家的得分，并显示最高得分、当前等级和余下的飞船数。
得分是游戏的一项统计信息，因此我们在GameStats中添加一个score属性：
game_stats.py

class GameStats():"""跟踪游戏的统计信息"""def __init__(self,ai_settings):"""初始化统计信息"""self.ai_settings = ai_settingsself.reset_stats()#游戏刚开始处于非活动状态self.game_active = Falsedef reset_stats(self):"""初始化在游戏运行期间可能变化的统计信息"""self.ships_left = self.ai_settings.ship_limitself.score = 0

3.1 显示得分

为了在屏幕上显示得分，我们创建一个新类Scoreboard，保存在scoreboard.py中：
scoreboard.py

import pygame.fontclass Scoreboard():"""显示得分信息的类"""def __init__(self,ai_settings,screen,stats):"""初始化显示得分涉及的属性"""self.screen  = screenself.screen_rect = screen.get_rect()self.ai_settings = ai_settingsself.stats = stats#显示得分信息时使用的字体设置self.text_color = (30,30,30)self.font = pygame.font.SysFont(None,48)#准备初始得分图像self.prep_score()def prep_score(self):"""将得分转换为一副渲染的图像"""score_str = str(self.stats.score)self.score_image = self.font.render(score_str,True,self.text_color,self.ai_settings.bg_color)#将得分放在屏幕右上角self.score_rect = self.score_image.get_rect()self.score_rect.right = self.screen_rect.right - 20self.score_rect.top = 20def show_score(self):"""在屏幕上显示得分"""#这个方法把得分图像显示在屏幕上self.screen.blit(self.score_image,self.score_rect)

3.2 创建记分牌

为显示得分，我们在alien_invasion.py中创建一个Scoreboard实例：
alien_invasion.py

import pygame
from settings import Settings
from game_stats import GameStats
from ship import Ship
from alien import Alien
import game_functions as gf
from pygame.sprite import Group
from button import Button  #导入button类
from scoreboard import Scoreboarddef 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Play按钮,并创建一个button实例play_button = Button(ai_settings,screen,"play") #创建一个外星人alien = Alien(ai_settings,screen)#创建一个用于存储游戏统计信息的实例,并创建记分牌stats = GameStats(ai_settings)sb = Scoreboard(ai_settings,screen,stats)#创建一艘非飞船ship = Ship(ai_settings,screen)#创建一个用于存储子弹的编组bullets = Group()aliens = Group()#创建外星人群gf.create_fleet(ai_settings,screen,ship,aliens)#开始游戏的主循环while True:#   sys.pause()#监视键盘和鼠标事件gf.check_events(ai_settings,screen,stats,play_button,ship,aliens,bullets)if stats.game_active:ship.update()gf.update_bullets(ai_settings,screen,ship,aliens,bullets)gf.update_aliens(ai_settings,stats,screen,ship,aliens,bullets)gf.update_screen(ai_settings,screen,stats,sb,ship,bullets,aliens,play_button)run_game()

还需要修改update_screen()
game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)def check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen, stats, play_button,ship,aliens,bullets):"""响应按键和鼠标事件"""for event in pygame.event.get():if event.type == pygame.QUIT:sys.exit(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？elif event.type == pygame.KEYDOWN:check_keydown_events(event, ai_settings,screen,ship, bullets)elif event.type == pygame.KEYUP:check_keyup_events(event,ship)elif event.type == pygame.MOUSEBUTTONDOWN:mouse_x, mouse_y = pygame.mouse.get_pos()check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y)def check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y):"""在玩家单击Play按钮时开始游戏"""button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)if button_clicked and not stats.game_active:#重置游戏设置ai_settings.initialize_dynamic_settings()#隐藏光标pygame.mouse.set_visible(False)#重置游戏统计信息stats.reset_stats()stats.game_active = True#清空外星人列表和子弹列表aliens.empty()bullets.empty()#创建一群新的外星人，并让飞船居中create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()def update_screen(ai_settings,screen,stats,sb,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#显示得分sb.show_score()#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if len(aliens) == 0:#删除现有的子弹并新建一群外星人#删除现有的子弹，加快游戏节奏，并创建一群新的外星人bullets.empty()ai_settings.increase_speed()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,ship,aliens):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):print("Ship hit!!!")def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)sys.exit(0)else:stats.game_active = Falsepygame.mouse.set_visible(True)def check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)

运行游戏发现屏幕右上角显示0.

3.3 在外星人被消灭时更新得分

为在屏幕上实时地显示得分，每当有外星人被击中时，我们都更新stats.score的值，在调用prep_score()更新得分图像。
settings.py

class Settings():"""存储<<外星人入侵>>的所有设置的类"""def __init__(self):"""初始化游戏的设置"""#屏幕设置self.screen_width = 800self.screen_height = 600self.bg_color = (230,230,230)#飞船的设置self.ship_speed_factor = 1.5self.ship_limit = 3#子弹设置self.bullet_speed_factor = 3self.bullet_width = 3self.bullet_height = 15self.bullet_color = (60 , 60 , 60)self.bullets_allowed = 5   #将在屏幕内可以存在的子弹限制为3颗#外星人设置self.alien_speed_factor = 1self.fleet_drop_speed = 10#以什么样的速度加快游戏节奏self.speedup_scale = 1.1self.initialize_dynamic_settings()def initialize_dynamic_settings(self):"""初始化随游戏进行而变化的设置"""#该方法设置了飞船、子弹和外星人的初始速度self.ship_speed_factor = 1.5self.bullet_speed_factor = 3self.alien_speed_factor = 1#fleet_direction为1表示向右移，为-1表示向左移self.fleet_direction = 1#计分self.alien_points = 50def increase_speed(self):"""提高速度设置"""#使用该方法在玩家提高一个等级时，来提高飞船、子弹和外星人的速度self.ship_speed_factor *= self.speedup_scaleself.bullet_speed_factor *= self.speedup_scaleself.alien_speed_factor *=self.speedup_scale

也就是每击落一个外星人得50分。
在check_bullet_alien_collisions()中，每当有外星人被击落时，都更新得分：
game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)def check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen, stats, play_button,ship,aliens,bullets):"""响应按键和鼠标事件"""for event in pygame.event.get():if event.type == pygame.QUIT:sys.exit(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？elif event.type == pygame.KEYDOWN:check_keydown_events(event, ai_settings,screen,ship, bullets)elif event.type == pygame.KEYUP:check_keyup_events(event,ship)elif event.type == pygame.MOUSEBUTTONDOWN:mouse_x, mouse_y = pygame.mouse.get_pos()check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y)def check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y):"""在玩家单击Play按钮时开始游戏"""button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)if button_clicked and not stats.game_active:#重置游戏设置ai_settings.initialize_dynamic_settings()#隐藏光标pygame.mouse.set_visible(False)#重置游戏统计信息stats.reset_stats()stats.game_active = True#清空外星人列表和子弹列表aliens.empty()bullets.empty()#创建一群新的外星人，并让飞船居中create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()def update_screen(ai_settings,screen,stats,sb,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#显示得分sb.show_score()#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if collisions:stats.score += ai_settings.alien_pointssb.prep_score()if len(aliens) == 0:#删除现有的子弹并新建一群外星人#删除现有的子弹，加快游戏节奏，并创建一群新的外星人bullets.empty()ai_settings.increase_speed()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,ship,aliens):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):print("Ship hit!!!")def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)sys.exit(0)else:stats.game_active = Falsepygame.mouse.set_visible(True)def check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)

有子弹撞到外星人时，Pygame返回一个字典(collisions)。然后检查这个字典是否存在，如果存在，就将得分加上一个外星人值的点数，接下来调用prep_score()来创建一副显示最新得分的新图像。
game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)def check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen, stats, play_button,ship,aliens,bullets):"""响应按键和鼠标事件"""for event in pygame.event.get():if event.type == pygame.QUIT:sys.exit(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？elif event.type == pygame.KEYDOWN:check_keydown_events(event, ai_settings,screen,ship, bullets)elif event.type == pygame.KEYUP:check_keyup_events(event,ship)elif event.type == pygame.MOUSEBUTTONDOWN:mouse_x, mouse_y = pygame.mouse.get_pos()check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y)def check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y):"""在玩家单击Play按钮时开始游戏"""button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)if button_clicked and not stats.game_active:#重置游戏设置ai_settings.initialize_dynamic_settings()#隐藏光标pygame.mouse.set_visible(False)#重置游戏统计信息stats.reset_stats()stats.game_active = True#清空外星人列表和子弹列表aliens.empty()bullets.empty()#创建一群新的外星人，并让飞船居中create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()def update_screen(ai_settings,screen,stats,sb,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#显示得分sb.show_score()#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if collisions:stats.score += ai_settings.alien_pointssb.prep_score()if len(aliens) == 0:#删除现有的子弹并新建一群外星人#删除现有的子弹，加快游戏节奏，并创建一群新的外星人bullets.empty()ai_settings.increase_speed()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,ship,aliens):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):print("Ship hit!!!")def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)sys.exit(0)else:stats.game_active = Falsepygame.mouse.set_visible(True)def check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)

alien_invasion.py中也应该更新：

import pygame
from settings import Settings
from game_stats import GameStats
from ship import Ship
from alien import Alien
import game_functions as gf
from pygame.sprite import Group
from button import Button  #导入button类
from scoreboard import Scoreboarddef 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Play按钮,并创建一个button实例play_button = Button(ai_settings,screen,"play") #创建一个外星人alien = Alien(ai_settings,screen)#创建一个用于存储游戏统计信息的实例,并创建记分牌stats = GameStats(ai_settings)sb = Scoreboard(ai_settings,screen,stats)#创建一艘非飞船ship = Ship(ai_settings,screen)#创建一个用于存储子弹的编组bullets = Group()aliens = Group()#创建外星人群gf.create_fleet(ai_settings,screen,ship,aliens)#开始游戏的主循环while True:#   sys.pause()#监视键盘和鼠标事件gf.check_events(ai_settings,screen,stats,play_button,ship,aliens,bullets)if stats.game_active:ship.update()gf.update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets)gf.update_aliens(ai_settings,stats,screen,ship,aliens,bullets)gf.update_screen(ai_settings,screen,stats,sb,ship,bullets,aliens,play_button)run_game()

3.4 将消灭的每个外星人的点数都计入得分

目前的计分值会遗漏被消灭的外星人。为了解决这个bug，我们来调整检测子弹和外星人碰撞的方式。
在check_bullet_alien_collisions()中，与外星人碰撞的子弹是字典collisions中的一个键；而与每颗子弹相关的值都是一个列表，其中包含该子弹撞到的外星人。我们遍历字典collisions，确保将消灭的每个外星人的点数都计入得分：
game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)def check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen, stats, play_button,ship,aliens,bullets):"""响应按键和鼠标事件"""for event in pygame.event.get():if event.type == pygame.QUIT:sys.exit(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？elif event.type == pygame.KEYDOWN:check_keydown_events(event, ai_settings,screen,ship, bullets)elif event.type == pygame.KEYUP:check_keyup_events(event,ship)elif event.type == pygame.MOUSEBUTTONDOWN:mouse_x, mouse_y = pygame.mouse.get_pos()check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y)def check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y):"""在玩家单击Play按钮时开始游戏"""button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)if button_clicked and not stats.game_active:#重置游戏设置ai_settings.initialize_dynamic_settings()#隐藏光标pygame.mouse.set_visible(False)#重置游戏统计信息stats.reset_stats()stats.game_active = True#清空外星人列表和子弹列表aliens.empty()bullets.empty()#创建一群新的外星人，并让飞船居中create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()def update_screen(ai_settings,screen,stats,sb,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#显示得分sb.show_score()#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if collisions:for aliens in collisions.values():stats.score += ai_settings.alien_pointssb.prep_score()if len(aliens) == 0:#删除现有的子弹并新建一群外星人#删除现有的子弹，加快游戏节奏，并创建一群新的外星人bullets.empty()ai_settings.increase_speed()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,ship,aliens):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):print("Ship hit!!!")def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)sys.exit(0)else:stats.game_active = Falsepygame.mouse.set_visible(True)def check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)

3.5 提高点数

settings.py

class Settings():"""存储<<外星人入侵>>的所有设置的类"""def __init__(self):"""初始化游戏的设置"""#屏幕设置self.screen_width = 800self.screen_height = 600self.bg_color = (230,230,230)#飞船的设置self.ship_speed_factor = 1.5self.ship_limit = 3#子弹设置self.bullet_speed_factor = 3self.bullet_width = 3self.bullet_height = 15self.bullet_color = (60 , 60 , 60)self.bullets_allowed = 5   #将在屏幕内可以存在的子弹限制为3颗#外星人设置self.alien_speed_factor = 1self.fleet_drop_speed = 10#以什么样的速度加快游戏节奏self.speedup_scale = 1.1#外星人点数的提高速度self.score_scale = 1.5self.initialize_dynamic_settings()def initialize_dynamic_settings(self):"""初始化随游戏进行而变化的设置"""#该方法设置了飞船、子弹和外星人的初始速度self.ship_speed_factor = 1.5self.bullet_speed_factor = 3self.alien_speed_factor = 1#fleet_direction为1表示向右移，为-1表示向左移self.fleet_direction = 1#计分self.alien_points = 50def increase_speed(self):"""提高速度设置"""#使用该方法在玩家提高一个等级时，来提高飞船、子弹和外星人的速度self.ship_speed_factor *= self.speedup_scaleself.bullet_speed_factor *= self.speedup_scaleself.alien_speed_factor *=self.speedup_scaleself.alien_points = int(self.alien_points * self.score_scales)print(self.alien_points)

3.6 将得分圆整

大多数街机风格的射击游戏都将得分显示为10的整数倍，我们的计分系统也将遵循这个原则，在设置一些规则，在大数字中添加用逗号表示的千位分隔符，我们在scoreboard.py中修改
scoreboard.py

import pygame.fontclass Scoreboard():"""显示得分信息的类"""def __init__(self,ai_settings,screen,stats):"""初始化显示得分涉及的属性"""self.screen  = screenself.screen_rect = screen.get_rect()self.ai_settings = ai_settingsself.stats = stats#显示得分信息时使用的字体设置self.text_color = (30,30,30)self.font = pygame.font.SysFont(None,48)#准备初始得分图像self.prep_score()def prep_score(self):"""将得分转换为一副渲染的图像"""rounded_score = int(round(self.stats.score, -1))score_str = "{:,}".format(rounded_score)#score_str = str(self.stats.score)self.score_image = self.font.render(score_str,True,self.text_color,self.ai_settings.bg_color)#将得分放在屏幕右上角self.score_rect = self.score_image.get_rect()self.score_rect.right = self.screen_rect.right - 20self.score_rect.top = 20def show_score(self):"""在屏幕上显示得分"""self.screen.blit(self.score_image,self.score_rect)

注意：在python2.7中，round()总是返回一个小数值，因此我们使用int()来确保报告的得分为整数。如果在python3中，可省略对int()的调用

3.7 最高得分

我们将最高得分存储在GameStats中:
game_stats.py

class GameStats():"""跟踪游戏的统计信息"""def __init__(self,ai_settings):"""初始化统计信息"""self.ai_settings = ai_settingsself.reset_stats()#游戏刚开始处于非活动状态self.game_active = False#在任何情况下都不应该重置最高得分self.high_score = 0def reset_stats(self):"""初始化在游戏运行期间可能变化的统计信息"""self.ships_left = self.ai_settings.ship_limitself.score = 0

下面来修改Scoreboard以显示最高分
scoreboard.py

import pygame.fontclass Scoreboard():"""显示得分信息的类"""def __init__(self,ai_settings,screen,stats):"""初始化显示得分涉及的属性"""self.screen  = screenself.screen_rect = screen.get_rect()self.ai_settings = ai_settingsself.stats = stats#显示得分信息时使用的字体设置self.text_color = (30,30,30)self.font = pygame.font.SysFont(None,48)#准备初始得分图像self.prep_score()self.prep_high_score()def prep_score(self):"""将得分转换为一副渲染的图像"""rounded_score = int(round(self.stats.score, -1))score_str = "{:,}".format(rounded_score)#score_str = str(self.stats.score)self.score_image = self.font.render(score_str,True,self.text_color,self.ai_settings.bg_color)#将得分放在屏幕右上角self.score_rect = self.score_image.get_rect()self.score_rect.right = self.screen_rect.right - 20self.score_rect.top = 20def show_score(self):"""在屏幕上显示得分"""self.screen.blit(self.score_image,self.score_rect)self.screen.blit(self.high_score_image,self.high_score_rect)def prep_high_score(self):"""将最高得分转换为渲染的图像"""high_score = int(round(self.stats.high_score, -1))high_score_str = "{:,}".format(high_score)self.high_score_image = self.font.render(high_score_str,True,self.text_color,self.ai_settings.bg_color)#将最高得分放在屏幕顶部中央self.high_score_rect = self.high_score_image.get_rect()self.high_score_rect.centerx = self.screen_rect.centerxself.high_score_rect.top = self.score_rect.top

根据最高分生成一幅图像，使其水平居中，将其top属性设置为当前得分图像的top属性。
现在方法show_score()在屏幕右上角显示当前得分，并在屏幕顶部中央显示最高得分。
为了检查是否诞生新的最高分，我们在game_functions.py中添加一个新函数check_high_score():
game_function.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)def check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen, stats, play_button,ship,aliens,bullets):"""响应按键和鼠标事件"""for event in pygame.event.get():if event.type == pygame.QUIT:sys.exit(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？elif event.type == pygame.KEYDOWN:check_keydown_events(event, ai_settings,screen,ship, bullets)elif event.type == pygame.KEYUP:check_keyup_events(event,ship)elif event.type == pygame.MOUSEBUTTONDOWN:mouse_x, mouse_y = pygame.mouse.get_pos()check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y)def check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y):"""在玩家单击Play按钮时开始游戏"""button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)if button_clicked and not stats.game_active:#重置游戏设置ai_settings.initialize_dynamic_settings()#隐藏光标pygame.mouse.set_visible(False)#重置游戏统计信息stats.reset_stats()stats.game_active = True#清空外星人列表和子弹列表aliens.empty()bullets.empty()#创建一群新的外星人，并让飞船居中create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()def update_screen(ai_settings,screen,stats,sb,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#显示得分sb.show_score()#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if collisions:for aliens in collisions.values():stats.score += ai_settings.alien_pointssb.prep_score()check_high_score(stats,sb)if len(aliens) == 0:#删除现有的子弹并新建一群外星人#删除现有的子弹，加快游戏节奏，并创建一群新的外星人bullets.empty()ai_settings.increase_speed()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,ship,aliens):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):print("Ship hit!!!")def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)sys.exit(0)else:stats.game_active = Falsepygame.mouse.set_visible(True)def check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)def check_high_score(stats,sb):"""检查是否诞生了新的最高分"""if stats.score > stats.high_score:stats.high_score = stats.scoresb.prep_high_score()

3.8 显示等级

想要在游戏中显示玩家的等级，需要在GameStats中添加一个表示当前等级的属性。为确保每次开始新游戏时都重置等级，在reset_stats()中初始化它：
game_stats.py

class GameStats():"""跟踪游戏的统计信息"""def __init__(self,ai_settings):"""初始化统计信息"""self.ai_settings = ai_settingsself.reset_stats()#游戏刚开始处于非活动状态self.game_active = False#在任何情况下都不应该重置最高得分self.high_score = 0def reset_stats(self):"""初始化在游戏运行期间可能变化的统计信息"""self.ships_left = self.ai_settings.ship_limitself.score = 0self.level = 1

scoreboard.py

import pygame.fontclass Scoreboard():"""显示得分信息的类"""def __init__(self,ai_settings,screen,stats):"""初始化显示得分涉及的属性"""self.screen  = screenself.screen_rect = screen.get_rect()self.ai_settings = ai_settingsself.stats = stats#显示得分信息时使用的字体设置self.text_color = (30,30,30)self.font = pygame.font.SysFont(None,48)#准备初始得分图像self.prep_score()self.prep_high_score()self.prep_level()def prep_score(self):"""将得分转换为一副渲染的图像"""rounded_score = int(round(self.stats.score, -1))score_str = "{:,}".format(rounded_score)#score_str = str(self.stats.score)self.score_image = self.font.render(score_str,True,self.text_color,self.ai_settings.bg_color)#将得分放在屏幕右上角self.score_rect = self.score_image.get_rect()self.score_rect.right = self.screen_rect.right - 20self.score_rect.top = 20def show_score(self):"""在屏幕上显示得分"""self.screen.blit(self.score_image,self.score_rect)self.screen.blit(self.high_score_image,self.high_score_rect)self.screen.blit(self.level_image,self.level_rect)def prep_high_score(self):"""将最高得分转换为渲染的图像"""high_score = int(round(self.stats.high_score, -1))high_score_str = "{:,}".format(high_score)self.high_score_image = self.font.render(high_score_str,True,self.text_color,self.ai_settings.bg_color)#将最高得分放在屏幕顶部中央self.high_score_rect = self.high_score_image.get_rect()self.high_score_rect.centerx = self.screen_rect.centerxself.high_score_rect.top = self.score_rect.topdef prep_level(self):"""将等级转换为渲染的图像"""self.level_image = self.font.render(str(self.stats.level),True,self.text_color,self.ai_settings.bg_color)#将等级放在得分下方self.level_rect = self.level_image.get_rect()self.level_rect.right= self.score_rect.rightself.level_rect.top = self.score_rect.bottom + 10

game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)def check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen, stats, sb,play_button,ship,aliens,bullets):"""响应按键和鼠标事件"""for event in pygame.event.get():if event.type == pygame.QUIT:sys.exit(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？elif event.type == pygame.KEYDOWN:check_keydown_events(event, ai_settings,screen,ship, bullets)elif event.type == pygame.KEYUP:check_keyup_events(event,ship)elif event.type == pygame.MOUSEBUTTONDOWN:mouse_x, mouse_y = pygame.mouse.get_pos()check_play_button(ai_settings,screen,stats,sb,play_button,ship,aliens,bullets,mouse_x,mouse_y)def check_play_button(ai_settings,screen,stats,sb,play_button,ship,aliens,bullets,mouse_x,mouse_y):"""在玩家单击Play按钮时开始游戏"""button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)if button_clicked and not stats.game_active:#重置游戏设置ai_settings.initialize_dynamic_settings()#隐藏光标pygame.mouse.set_visible(False)#重置游戏统计信息stats.reset_stats()stats.game_active = True#重置记分牌图像sb.prep_score()sb.prep_high_score()sb.prep_level()#清空外星人列表和子弹列表aliens.empty()bullets.empty()#创建一群新的外星人，并让飞船居中create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()def update_screen(ai_settings,screen,stats,sb,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#显示得分sb.show_score()#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if collisions:for aliens in collisions.values():stats.score += ai_settings.alien_pointssb.prep_score()check_high_score(stats,sb)if len(aliens) == 0:#删除现有的子弹并新建一群外星人#删除现有的子弹，加快游戏节奏，并创建一群新的外星人bullets.empty()ai_settings.increase_speed()stats.level += 1sb.prep_level()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,ship,aliens):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):print("Ship hit!!!")def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)#sys.exit(0)stats.game_active = Falseelse:stats.game_active = Falsepygame.mouse.set_visible(True)def check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)def check_high_score(stats,sb):"""检查是否诞生了新的最高分"""if stats.score > stats.high_score:stats.high_score = stats.scoresb.prep_high_score()

alien_invasion.py

import sys
import pygame
from settings import Settings
from game_stats import GameStats
from ship import Ship
from alien import Alien
import game_functions as gf
from pygame.sprite import Group
from button import Button  #导入button类
from scoreboard import Scoreboarddef 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Play按钮,并创建一个button实例play_button = Button(ai_settings,screen,"play") #创建一个外星人alien = Alien(ai_settings,screen)#创建一个用于存储游戏统计信息的实例,并创建记分牌stats = GameStats(ai_settings)sb = Scoreboard(ai_settings,screen,stats)#创建一艘非飞船ship = Ship(ai_settings,screen)#创建一个用于存储子弹的编组bullets = Group()aliens = Group()#创建外星人群gf.create_fleet(ai_settings,screen,ship,aliens)#开始游戏的主循环while True:#sys.pause()#监视键盘和鼠标事件gf.check_events(ai_settings,screen,stats,sb,play_button,ship,aliens,bullets)if stats.game_active:ship.update()gf.update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets)gf.update_aliens(ai_settings,stats,screen,ship,aliens,bullets)gf.update_screen(ai_settings,screen,stats,sb,ship,bullets,aliens,play_button)run_game()

4.9 显示余下的飞船数

最后，我们来显示玩家还有多少艘飞船，使用图形的方式，为此，我们需要在屏幕左上角绘制飞船图像来指出还余下多少艘飞船。
ship.py

import pygame
from pygame.sprite import Spriteclass Ship(Sprite):def __init__(self,ai_settings,screen):"""初始化飞船并设置其初始化位置"""super(Ship,self).__init__()self.screen = screenself.ai_settings = ai_settings#加载飞船图像并获取其外接矩形self.image = pygame.image.load('images/ship.bmp')self.rect = self.image.get_rect()self.screen_rect = screen.get_rect()#将每艘新飞船放在屏幕底部中央self.rect.centerx = self.screen_rect.centerxself.rect.bottom = self.screen_rect.bottom#在飞船的属性center中存储小数值self.center = float(self.rect.centerx)#移动标志self.moving_right = Falseself.moving_left = Falseself.moving_up = Falseself.moving_down = Falsedef update(self):"""根据移动标志调整飞船的位置"""#更新飞船的center值，而不是rectif self.moving_right and self.rect.right < self.screen_rect.right:self.center += self.ai_settings.ship_speed_factorelif self.moving_left and self.rect.left > 0:self.center -= self.ai_settings.ship_speed_factorelif self.moving_up and self.rect.up < self.screen_rect.up:self.center += self.ai_settings.ship_speed_factorelif self.moving_down and self.rect.down > 0:self.center -= self.ai_settings.ship_speed_factor#根据self.center更新rect对象self.rect.centerx = self.centerdef blitme(self):"""在指定位置绘制飞船"""self.screen.blit(self.image,self.rect)def center_ship(self):"""让飞船在屏幕上居中"""self.center = self.screen_rect.centerx

scoreboard.py

import pygame.font
from pygame.sprite import Group
from ship import Shipclass Scoreboard():"""显示得分信息的类"""def __init__(self,ai_settings,screen,stats):"""初始化显示得分涉及的属性"""self.screen  = screenself.screen_rect = screen.get_rect()self.ai_settings = ai_settingsself.stats = stats#显示得分信息时使用的字体设置self.text_color = (30,30,30)self.font = pygame.font.SysFont(None,48)#准备初始得分图像self.prep_score()self.prep_high_score()self.prep_level()self.prep_ships()def prep_score(self):"""将得分转换为一副渲染的图像"""rounded_score = int(round(self.stats.score, -1))score_str = "{:,}".format(rounded_score)#score_str = str(self.stats.score)self.score_image = self.font.render(score_str,True,self.text_color,self.ai_settings.bg_color)#将得分放在屏幕右上角self.score_rect = self.score_image.get_rect()self.score_rect.right = self.screen_rect.right - 20self.score_rect.top = 20def show_score(self):"""在屏幕上显示得分"""self.screen.blit(self.score_image,self.score_rect)self.screen.blit(self.high_score_image,self.high_score_rect)self.screen.blit(self.level_image,self.level_rect)#绘制飞船self.ships.draw(self.screen)def prep_high_score(self):"""将最高得分转换为渲染的图像"""high_score = int(round(self.stats.high_score, -1))high_score_str = "{:,}".format(high_score)self.high_score_image = self.font.render(high_score_str,True,self.text_color,self.ai_settings.bg_color)#将最高得分放在屏幕顶部中央self.high_score_rect = self.high_score_image.get_rect()self.high_score_rect.centerx = self.screen_rect.centerxself.high_score_rect.top = self.score_rect.topdef prep_level(self):"""将等级转换为渲染的图像"""self.level_image = self.font.render(str(self.stats.level),True,self.text_color,self.ai_settings.bg_color)#将等级放在得分下方self.level_rect = self.level_image.get_rect()self.level_rect.right= self.score_rect.rightself.level_rect.top = self.score_rect.bottom + 10#该方法创建一个空的编组self.ships,用于存储飞船的实例def prep_ships(self):"""显示还余下多少艘飞船"""self.ships = Group()for ship_number in range(self.stats.ship_left):ship = Ship(self.ai_settings,self.screen)ship.rect.x = 10 + ship_number * ship,rect.widthship.rect.y = 10self.ships.add(ship)

game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleepdef check_keydown_events(event,ai_settings,screen, stats,ship,bullets):"""响应按键"""if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit(0)elif event.key == pygame.K_p:stats.game_active = Truedef check_keyup_events(event,ship):"""响应松开"""if event.key == pygame.K_RIGHT:ship.moving_right = Falseif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen, stats, sb,play_button,ship,aliens,bullets):"""响应按键和鼠标事件"""for event in pygame.event.get():if event.type == pygame.QUIT:sys.exit(0)  #在这里的exit()中需要传递参数，他么的，竟然这么坑吗？elif event.type == pygame.KEYDOWN:check_keydown_events(event, ai_settings,screen,stats,ship, bullets)elif event.type == pygame.KEYUP:check_keyup_events(event,ship)elif event.type == pygame.MOUSEBUTTONDOWN:mouse_x, mouse_y = pygame.mouse.get_pos()check_play_button(ai_settings,screen,stats,sb,play_button,ship,aliens,bullets,mouse_x,mouse_y)def check_play_button(ai_settings,screen,stats,sb,play_button,ship,aliens,bullets,mouse_x,mouse_y):"""在玩家单击Play按钮时开始游戏"""button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)if button_clicked and not stats.game_active:#重置游戏设置ai_settings.initialize_dynamic_settings()#隐藏光标pygame.mouse.set_visible(False)#重置游戏统计信息stats.reset_stats()stats.game_active = True#重置记分牌图像sb.prep_score()sb.prep_high_score()sb.prep_level()sb.prep_ships()#清空外星人列表和子弹列表aliens.empty()bullets.empty()#创建一群新的外星人，并让飞船居中create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()def update_screen(ai_settings,screen,stats,sb,ship,bullets,aliens,play_button):"""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)#在飞船和外星人后面重绘所有子弹for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()aliens.draw(screen)#显示得分sb.show_score()#如果游戏处于非活动状态，就绘制Play按钮if not stats.game_active:play_button.draw_button()#让最近绘制的屏幕可见pygame.display.flip()def update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets):"""更新子弹的位置，并删除已销失的子弹"""#更新子弹的位置bullets.update()#删除已销失的子弹for bullet in bullets.copy():if bullet.rect.bottom <= 0:bullets.remove(bullet)if len(bullets) != 0:print(len(bullets))#检查是否有子弹击中了外星人#如果这样，就删除相应的子弹和外星人check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets)def check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets):"""响应子弹和外星人的碰撞"""#删除发生碰撞的子弹和外星人collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)if collisions:for aliens in collisions.values():stats.score += ai_settings.alien_pointssb.prep_score()check_high_score(stats,sb)if len(aliens) == 0:#删除现有的子弹并新建一群外星人#删除现有的子弹，加快游戏节奏，并创建一群新的外星人bullets.empty()ai_settings.increase_speed()stats.level += 1sb.prep_level()create_fleet(ai_settings,screen,ship,aliens)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 get_number_aliens_x(ai_settings,alien_width):"""计算每行可容纳多少外星人"""available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_alien_x = int(available_space_x / (2 * alien_width))return number_alien_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):"""创建一个外星人并将其加入当前行"""alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):"""创建外星人"""#创建一个外星人，并计算一行可容纳多少外星人#外星人间距为外星人宽度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)#创建第一行外星人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)def update_aliens(ai_settings,screen,stats,sb,ship,aliens,bullets):"""更新外星人群中所有外星人的位置"""aliens.update()#检测外星人和飞船之间的碰撞if pygame.sprite.spritescollideany(ship,aliens):ship_hit(ai_settings,screen,stats,sb,ship,aliens,bullets)print("Ship hit!!!")check_aliens_bottom(ai_settings,screen,stats,sb, ship,aliens,bullets)def check_fleet_edges(ai_settings,aliens):"""有外星人到达边缘时采取相应的措施"""for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):"""将整群外星人下移，并改变它们的方向"""for alien in aliens.sprites():alien.rect.y += ai_settings.fleet_drop_speedai_settings.fleet_direction *= -1def ship_hit(ai_settings,stats,screen,sb,ship,aliens,bullets):"""相应被外星人撞到的飞船"""if stats.ships_left > 0:#将ships_left 减1stats.ships_left -= 1#更新记分牌sb.prep_ships()#清空外星人到列表和子弹列表aliens.empty()bullets.empty()#创建一群外星人，并将飞船放到屏幕底端中央create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()#暂停sleep(0.5)#sys.exit(0)#stats.game_active = Falseelse:stats.game_active = Falsepygame.mouse.set_visible(True)def check_aliens_bottom(ai_settings,stats,screen,sb,ship,aliens,bullets):"""检查是否有外星人到达了屏幕底端"""screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:#像飞船被撞到一样进行处理ship_hit(ai_settings,stats,screen,sb,ship,aliens,bullets)breakdef update_aliens(ai_settings,stats,screen,sb,ship,aliens,bullets):"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,stats,screen,sb,ship,aliens,bullets)#检查是否有外星人到达屏幕底端check_aliens_bottom(ai_settings,stats,screen,sb,ship,aliens,bullets)def check_high_score(stats,sb):"""检查是否诞生了新的最高分"""if stats.score > stats.high_score:stats.high_score = stats.scoresb.prep_high_score()

alien_invasion.py

import sys
import pygame
from settings import Settings
from game_stats import GameStats
from ship import Ship
from alien import Alien
import game_functions as gf
from pygame.sprite import Group
from button import Button  #导入button类
from scoreboard import Scoreboarddef 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Play按钮,并创建一个button实例play_button = Button(ai_settings,screen,"play") #创建一个外星人alien = Alien(ai_settings,screen)#创建一个用于存储游戏统计信息的实例,并创建记分牌stats = GameStats(ai_settings)sb = Scoreboard(ai_settings,screen,stats)#创建一艘非飞船ship = Ship(ai_settings,screen)#创建一个用于存储子弹的编组bullets = Group()aliens = Group()#创建外星人群gf.create_fleet(ai_settings,screen,ship,aliens)#开始游戏的主循环while True:#sys.pause()#监视键盘和鼠标事件gf.check_events(ai_settings,screen,stats,sb,play_button,ship,aliens,bullets)if stats.game_active:ship.update()gf.update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets)gf.update_aliens(ai_settings,stats,screen,sb,ship,aliens,bullets)gf.update_screen(ai_settings,screen,stats,sb,ship,bullets,aliens,play_button)run_game()