话接上回： https://www.cnblogs.com/yue-qian/p/14379618.html

 

 实现这个小游戏需要玩家控制的飞船（ship），外星人(alien)，开始按钮（button），玩家控制飞船射出的子弹（bullet）以及计分板。下面就依次实现各个模块。

ship模块如下：

import pygame
from pygame.sprite import Sprite

class Ship(Sprite):

    def __init__(self, ai_settings, screen):
        super(Ship, self).__init__()
        self.screen = screen
        #获取飞船移动速率 
        self.ai_settings = ai_settings
        #设置飞船图像并且获取飞船外接矩形
        self.image = pygame.image.load('images/ship.bmp')
        self.rect = self.image.get_rect()
        self.screen_rect = screen.get_rect()
        #飞船位置
        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom
        
        self.center = float(self.rect.centerx)
        #移动标志
        self.moving_right = False
        self.moving_left = False
        
    def center_ship(self):
        self.center = self.screen_rect.centerx
        
    def update(self):
        #更新飞船位置
        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

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

 

 bullet模块如下：

import pygame
from pygame.sprite import Sprite

class Bullet(Sprite):
    """A class to manage bullets fired from the ship."""

    def __init__(self, ai_settings, screen, ship):
        
        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
        
       #子弹位置设置为小数
        self.y = float(self.rect.y)
        #设置子弹的一些参数
        self.color = ai_settings.bullet_color
        self.speed_factor = ai_settings.bullet_speed_factor

    def update(self):
        """Move the bullet up the screen."""
        #更新子弹位置
        self.y -= self.speed_factor
        #更新子弹外接矩形
        self.rect.y = self.y

    def draw_bullet(self):
        """Draw the bullet to the screen."""
        pygame.draw.rect(self.screen, self.color, self.rect)

button模块如下：

import pygame.font

class Button():

    def __init__(self, ai_settings, screen, msg):

        self.screen = screen
        self.screen_rect = screen.get_rect()

        self.width, self.height = 200, 50
        self.button_color = (0, 255, 0)
        self.text_color = (255, 255, 255)
        self.font = pygame.font.SysFont(None, 48)
        
        self.rect = pygame.Rect(0, 0, self.width, self.height)
        self.rect.center = self.screen_rect.center
        

        self.prep_msg(msg)

    def prep_msg(self, msg):
       
        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
        
    def draw_button(self):
 
        self.screen.fill(self.button_color, self.rect)
        self.screen.blit(self.msg_image, self.msg_image_rect)