目前在学习《python编程:从入门到实践》这本书,完成第一个项目“外星人入侵”时所遇到的问题如下图,诡异的是这个错误不是每次运行alien_invasion时都出现(前几次运行都能正确的完成相应的逻辑功能),出现这个错误后我再次重新运行,有时候可以正常运行,有时候继续报这个错误。不知道啥原因,人都麻了。
alien.py 代码如下
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().__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.image = pygame.transform.scale(self.image, (45, 48))
self.rect = self.image.get_rect()
# 每个外星人最初都在屏幕左上角附近
# 每个外星人的左边距都设置为外星人的宽度,并将上边距设置为外星人的高度
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 check_edges(self):
# 如果外星人位于屏幕边缘,就返回True
screen_rect = self.screen.get_rect()
if self.rect.right >= screen_rect.right:
return True
elif self.rect.left <= 0:
return True
def update(self):
# 向左或向右移动外星人
self.x += (self.ai_settings.alien_speed_factor * self.ai_settings.fleet_direction)
self.rect.x =self.x
def blitme(self):
# 在指定位置绘制外星人
self.screen.blit(self.image, self.rect)
alien_invasion.py 代码如下
import pygame
from pygame.sprite import Group
from button import Button
from game_stats import GameStats
from ship import Ship
from settings import Settings
import game_functions as gf
def run_game():
# 初始化pygame、设置和屏幕对象
pygame.init()
ai_settings = Settings()
# 创建显示窗口,并指定了游戏窗口的尺寸px,注意使用了两个括号
screen = pygame.display.set_mode((ai_settings.screen_width, ai_settings.screen_height))
pygame.display.set_caption("Alien Invasion")
ship = Ship(ai_settings, screen) # 创建一艘飞船
bullets = Group() # 创建一个用于存储子弹的编组
aliens = Group() # 创建一个外星人编组
stats = GameStats(ai_settings) # 创建一个用于存储游戏统计信息的实例
gf.create_fleet(ai_settings, screen, ship, aliens) # 创建外星人群
play_button = Button(ai_settings, screen, 'Play') # 创建Play按钮
# 开始游戏的主循环
while True:
gf.check_events(ai_settings, screen, stats, play_button, ship, aliens, bullets) # 监视键盘和鼠标事件
if stats.game_active:
ship.update() # 更新飞船的位置
gf.update_bullets(ai_settings, screen, ship, aliens, bullets) # 更新所有未消失的子弹的位置
gf.update_aliens(ai_settings, stats, screen, ship, aliens, bullets)
gf.update_screen(ai_settings, screen, stats, ship, aliens, bullets, play_button) # 使用更新后的位置来重新绘制新屏幕
run_game() # 这将初始化游戏并开始主循环
bullet.py 代码块
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):
# 在飞船所在的位置创建一个子弹对象
super().__init__()
self.screen = screen
# 在(0,0)处创建一个表示子弹的矩形,再设正确的位置
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 # 将表示子弹的rect 的top属性设置为飞船的rect 的top 属性,让子弹看起来像是从飞船中射出的
# 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 # 发射出去后,子弹在屏幕中向上移动,这意味着y 坐标将不断减小
# 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)
button.py 代码块
import pygame.font # 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 = screen
self.screen_rect = screen.get_rect()
# 设置按钮的尺寸和其他属性
self.width, self.height = 200, 50
self.button_color = (67, 205, 128)
self.text_color = (255, 255, 255)
self.font = pygame.font.SysFont(None, 48) # 实参None 让Pygame 使用默认字体,48指定文本的字号。
# 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)
def prep_msg(self, msg):
# 将msg渲染为图像,并使其在按钮上居中
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):
# 描绘一个用颜色填充的按钮,再绘制文本
self.screen.fill(self.button_color, self.rect)
self.screen.blit(self.msg_image, self.msg_image_rect)
game_functions.py 代码块:
import sys # 玩家退出时,使用模块sys退出游戏
from time import sleep
import pygame
from alien import Alien
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_UP:
ship.moving_up = True
elif event.key == pygame.K_DOWN:
ship.moving_down = True
elif event.key == pygame.K_SPACE:
fire_bullet(ai_settings, screen, ship, bullets)
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
elif event.key == pygame.K_UP:
ship.moving_up = False
elif event.key == pygame.K_DOWN:
ship.moving_down = False
elif event.key == pygame.K_q:
sys.exit()
def 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: # 玩家单击游戏窗口关闭按钮时检测到
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)
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):
# 玩家单击Play按钮时开始新游戏
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, aliens, bullets, 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()
# 不断更新屏幕,让最近绘制的屏幕可见
# 在我们移动游戏元素时,pygame.display.flip() 将不断更新屏幕,以显示元素的新位置,并在原来的位置隐藏元素,从而营造平滑移动的效果。
pygame.display.flip()
def update_bullets(ai_settings, screen, ship, aliens, bullets):
# 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)
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):
# 如果没有到达限制,就发射一颗子弹
# 创建一颗子弹,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个外星人
avaliable_space_x = ai_settings.screen_width - 2 * alien_width
number_aliens_x = int(avaliable_space_x / (2 * alien_width))
return number_aliens_x
def get_number_rows(ai_settings, ship_height, alien_height):
# 计算屏幕可容纳多少行外星人
available_space_y = (ai_settings.screen_height - (3 * alien_height) - ship_height)
number_rows = int(available_space_y / (2 * alien_height))
return number_rows
def create_alien(ai_settings, screen, aliens, alien_number, row_number):
# 创建一个外星人并将其放在当前行
alien = Alien(ai_settings, screen)
alien_width = alien.rect.width # 从外星人的rect 属性中获取外星人宽度
alien.x = alien_width + 2 * alien_width * alien_number
alien.rect.x = alien.x
alien.rect.y = alien.rect.height + 2 * alien.rect.height * row_number
aliens.add(alien)
def create_fleet(ai_settings, screen, ship, aliens):
# 创建外星人群
# 创建一个外星人,并计算一行可容纳多少个外星人
# 外星人间距为外星人宽度
alien = Alien(ai_settings, screen)
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 alien_number in range(number_aliens_x):
# create_alien(ai_settings, screen, aliens, alien_number)
# 创建外星人群
for row_number in range(number_rows):
for alien_number in range(number_aliens_x):
create_alien(ai_settings, screen, aliens, alien_number, row_number)
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)
break
def change_fleet_direction(ai_settings, aliens):
# 将整群外星人向下移动,并改变它们的方向
for alien in aliens.sprites():
alien.rect.y += ai_settings.fleet_drop_speed
ai_settings.fleet_direction *= -1
def ship_hit(ai_settings, stats, screen, ship, aliens, bullets):
# 响应被外星人撞到的飞船
if stats.ships_left > 0:
# 将ship_left减 1
stats.ships_left -= 1
# 清空外星人列表和子弹列表
aliens.empty()
bullets.empty()
# 创建一群新外星人,并把飞船放到底部中央
create_fleet(ai_settings, screen, ship, aliens)
ship.center_ship()
# 暂停
sleep(0.5)
else:
stats.game_active = False
pygame.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部
screen_rect = screen.get_rect()
for alien in aliens.sprites():
if alien.rect.bottom >= screen_rect.bottom:
# 像被飞船撞到一样处理
ship_hit(ai_settings, stats, screen, ship, aliens, bullets)
break
def update_aliens(ai_settings, stats, screen, ship, aliens, bullets):
# 检查是否有外星人到达了屏幕底部
check_aliens_bottom(ai_settings, stats, screen, ship, aliens, bullets)
# 检查是否有外星人位于屏幕边缘,并更新外星人群中所有外星人的位置
check_fleet_edges(ai_settings, aliens)
aliens.update()
# 检测外星人和飞船之间的碰撞
if pygame.sprite.spritecollideany(ship, aliens):
ship_hit(ai_settings, stats, screen, ship, aliens, bullets)
game_stats.py 代码块
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_settings
self.reset_stats()
# 让游戏一开始处于非活动状态
self.game_active = False
def 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
settings 代码块
class Settings():
# 存储该项目所有设置的类
def __init__(self):
# 初始化游戏的设置
# 屏幕设置
self.screen_width = 1000
self.screen_height = 700
self.bg_color = (230, 230, 230)
# 飞船的设置
self.ship_left_right_speed_factor = 1.5 # 左右移动速度
self.ship_up_down_speed_factor = 1.5
self.ship_limit = 3
# 子弹设置
self.bullet_speed_factor = 3
self.bullet_width = 3
self.bullet_height = 15
self.bullet_color = 178, 34, 34
self.bullets_allowed = 3
# 外星人设置
self.alien_speed_factor = 0.3 # 外星人移动速度设置
self.fleet_drop_speed = 10 # 外星人群向下移动的速度
# fleet_direction为1表示向右移,为-1表示向左移
self.fleet_direction = 1
ship.py 代码块
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.image = pygame.transform.scale(self.image, (40, 70)) # 将Surface属性的self.image转化为30×30的大小
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.centerx = float(self.rect.centerx)
self.centery = float(self.rect.centery)
# 移动标志
self.moving_right = False
self.moving_left = False
self.moving_up = False
self.moving_down = 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
# 让飞船到达屏幕边缘后停止移动
if self.moving_right and (self.rect.right < self.screen_rect.right): # 标志为True时向右移动飞船
self.centerx += self.ai_settings.ship_left_right_speed_factor
if self.moving_left and (self.rect.left > 0):
self.centerx -= self.ai_settings.ship_left_right_speed_factor
if self.moving_down and (self.rect.bottom < self.screen_rect.bottom):
self.centery += self.ai_settings.ship_up_down_speed_factor
if self.moving_up and (self.rect.top > 0):
self.centery -= self.ai_settings.ship_up_down_speed_factor
# 根据self.centerx/y更新rect对象
self.rect.centerx = self.centerx
self.rect.centery = self.centery
def blitme(self):
# 在指定位置绘制飞船
self.screen.blit(self.image, self.rect)
def center_ship(self):
# 让飞船在屏幕居中
# self.center = self.screen_rect.centerx
self.rect.midbottom = self.screen_rect.midbottom
self.centerx = float(self.rect.centerx)
self.centery = float(self.rect.centery)