完成了外星人的创建

alien_invassion.py

import sys

import pygame

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

def run_game():
	#初始化游戏并创建一个屏幕对象
	pygame.init()
	ai_settings = Settings()
	screen = pygame.display.set_mode(
		(ai_settings.screen_width, ai_settings.screen_height))
	pygame.display.set_caption("Alien Invasion")

	#创建一艘飞船
	ship = Ship(ai_settings, screen)
	#创建一个存储子弹的编组
	bullets = Group()

	#创建一个外星人
	alien = Alien(ai_settings, screen)

	#开始游戏的主循环
	while True:
		gf.check_events(ai_settings, screen, ship, bullets)
		ship.update()
		gf.update_bullets(bullets)
		gf.update_screen(ai_settings, screen, ship, alien, bullets)
		
run_game()

game_functions.py

import sys

import pygame

from bullet import Bullet

def check_keydown_event(event, ai_settings, screen, ship, bullets):
	#相应按键
	if event.key == pygame.K_RIGHT:
		ship.moving_right = True
	elif event.key == pygame.K_LEFT:
		ship.moving_left = True
	elif event.key == pygame.K_UP:
		ship.moving_up = True
	elif event.key == pygame.K_DOWN:
		ship.moving_down = True
	elif event.key == pygame.K_SPACE:
		#创建一颗子弹，并将其加入到编组bullets中
		fire_bullet(ai_settings, screen, ship, bullets)
	elif event.key == pygame.K_q:
		sys.exit()
		
def check_keyup_event(event, ship):
	if event.key == pygame.K_RIGHT:
		ship.moving_right = False
	elif event.key == pygame.K_LEFT:
		ship.moving_left = False
	if event.key == pygame.K_UP:
		ship.moving_up = False
	elif event.key == pygame.K_DOWN:
		ship.moving_down = False

def check_events(ai_settings, screen, ship, bullets):
	#监视键盘和鼠标事件
	for event in pygame.event.get():
		if event.type == pygame.QUIT:
			sys.exit()
		elif event.type == pygame.KEYDOWN:
			check_keydown_event(event, ai_settings, screen, ship, bullets)
		elif event.type == pygame.KEYUP:
			check_keyup_event(event, ship)

def update_bullets(bullets):
	#更新子弹的位置，并删除已消失的子弹
	#更新子弹的位置
	bullets.update()

	#删除已消失的子弹
	for bullet in bullets.copy():
		if bullet.rect.bottom <= 0:
			bullets.remove(bullet)

def fire_bullet(ai_settings, screen, ship, bullets):
	#如果还没有达到限制，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 update_screen(ai_settings, screen, ship, alien, bullets):
	#更新屏幕上的图像，并切换到新屏幕
	#每次循环时都重绘屏幕
	screen.fill(ai_settings.bg_color)
	#在飞船和外星人后面重绘所有子弹
	for bullet in bullets:
		bullet.draw_bullet()#子弹绘制
	ship.blitme()
	alien.blitme()

	#让最近绘制的屏幕可见
	pygame.display.flip()

alien.py

import pygame
from pygame.sprite import Sprite

class Alien(Sprite):
	#表示单个外星人的类

	def __init__(self, ai_settings, screen):
		#初始化外星人并设置其起始位置
		super(Alien, self).__init__()
		self.screen = screen
		self.ai_settings = ai_settings

		#加载外星人图像，并设置其rect属性
		self.image = pygame.image.load('images/alien.bmp')
		self.rect = self.image.get_rect()

		#每个外星人最初都在屏幕左上角附近
		self.rect.x = self.rect.width
		self.rect.y = self.rect.height

		#存储外星人的准确位置
		self.x = float(self.rect.x)

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