Python 项目练习1 外星人入侵（武装飞船）

本项目具体步骤在书本《Python编程：从入门到实践》第十二章中

安装pygame

可通过pip安装：
python -m pip install --user pygame-1.9.2a0-cp35-none-win32.whl

Pygame窗口

alien_invasion.py

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

def run_game():     # 初始化游戏并创建一个屏幕对象 
    # 初始化pygame、设置和屏幕对象    
    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) 

    # 创建一个用于存储子弹的编组
    bullets = Group() 

    # 开始游戏的主循环    
    while True: 
        # 监视键盘和鼠标事件
        gf.check_events(ai_settings, screen, ship, bullets) 
        ship.update()
        gf.update_bullets(bullets)
        gf.update_screen(ai_settings, screen, ship, bullets)
 
run_game()

设置类

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 = 1200
        self.screen_height = 800
        self.bg_color = (230, 230, 230)
        # 飞船的设置
        self.ship_speed_factor = 1.5
        # 子弹设置
        self.bullet_speed_factor = 1
        self.bullet_width = 3
        self.bullet_height = 15
        self.bullet_color = 60, 60, 60 
        self.bullets_allowed = 3 

飞船图像

图片放到 images 文件夹里，图片名为 ship.bmp
图片后缀为.bmp

Ship 类

ship.py

import pygame 

class Ship():
    def __init__(self, ai_settings, screen):
        """初始化飞船并设置其初始位置"""
        self.screen = screen 
        self.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.centerx
        self.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 = False
        self.moving_left = False 

    def 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rect
        if self.moving_right and self.rect.right < self.screen_rect.right:
            self.center += self.ai_settings.ship_speed_factor
        if self.moving_left and self.rect.left > 0:
            self.center -= self.ai_settings.ship_speed_factor

        # 根据self.center更新rect对象
        self.rect.centerx = self.center 

    def blitme(self):
        """在指定位置绘制飞船"""
        self.screen.blit(self.image, self.rect) 

响应模块 game_functions

game_functions.py

import sys 
import pygame 
from bullet import Bullet

def check_keydown_events(event, ai_settings, screen, ship, bullets):
    """响应按键"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        ship.moving_left = True
    elif event.key == pygame.K_SPACE:
        fire_bullet(ai_settings, screen, ship, bullets) 
        
def fire_bullet(ai_settings, screen, ship, bullets):
    """如果还没有到达限制，就发射一颗子弹"""
    #创建新子弹，并将其加入到编组bullets中
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet) 
        
def check_keyup_events(event, ship):
    """响应松开"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = False
    elif event.key == pygame.K_LEFT:
        ship.moving_left = False 

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

def update_screen(ai_settings, screen, ship, 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.sprites():
        bullet.draw_bullet() 

    ship.blitme() 
 
    # 让最近绘制的屏幕可见
    pygame.display.flip()
def update_bullets(bullets):
    """更新子弹的位置，并删除已消失的子弹"""
    # 更新子弹的位置
    bullets.update()
    # 删除已消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet) 

Bullet 类

bullet.py

import pygame
from pygame.sprite import Sprite

class Bullet(Sprite):
    """一个对飞船发射的子弹进行管理的类"""
    def __init__(self, ai_settings, screen, ship):
        """在飞船所处的位置创建一个子弹对象"""
        super(Bullet, self).__init__()
        self.screen = screen

        # 在(0,0)处创建一个表示子弹的矩形，再设置正确的位置
        self.rect = pygame.Rect(0, 0, ai_settings.bullet_width,
            ai_settings.bullet_height)
        self.rect.centerx = ship.rect.centerx
        self.rect.top = ship.rect.top 

        #存储用小数表示的子弹位置
        self.y = float(self.rect.y)
        
        self.color = ai_settings.bullet_color
        self.speed_factor = ai_settings.bullet_speed_factor 
    
    def update(self):
        """向上移动子弹"""
        #更新表示子弹位置的小数值
        self.y -= self.speed_factor
        #更新表示子弹的rect的位置
        self.rect.y = self.y

    def draw_bullet(self):
        """在屏幕上绘制子弹"""
        pygame.draw.rect(self.screen, self.color, self.rect) 

效果图：