14-1 按P开始新游戏 ：鉴于游戏《外星人入侵》使用键盘来控制飞船，最好让玩家也能够通过按键来开始游戏。请添加让玩家在按P时开始游戏的代码。
alien-invasion.py
import pygame
from pygame.sprite import Group
from pygame.locals import *
from settings import Settings
from ship import Ship
from game_stats import Gamestats
from button import Button
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")
#创建一个用于游戏统计信息的实例
stats = Gamestats(ai_settings)
#创建一艘飞船、一个用于存储子弹的编组、一个用于存储外星人的编组
ship = Ship(screen, ai_settings)
bullets = Group()
aliens = Group()
#创建一个外星人群
gf.create_fleet(ai_settings, screen, ship, aliens)
#创建Play按钮
play_button = Button(ai_settings, screen, "Play")
#开始游戏的主循环
while True:
gf.check_events(ai_settings, screen, ship, bullets, stats, play_button, aliens)
if stats.game_active:
ship.update()
gf.update_bullets(ai_settings, screen, ship, aliens, bullets)
gf.update_aliens(ai_settings, stats, screen, ship, bullets, aliens)
gf.update_screen(ai_settings, screen, ship, aliens, bullets, stats, play_button)
run_game()
game_functions.py
import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleep
def check_events(ai_settings, screen, ship, bullets, stats, play_button, aliens):
"""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, stats, aliens)
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, aliens, bullets, ai_settings, screen, ship)
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_keydown_events(event, ai_settings, screen, ship, bullets, stats, aliens):
"""响应按键"""
if event.key == pygame.K_RIGHT:
#向右移动飞船
ship.moving_right = True
elif event.key == pygame.K_LEFT:
#向左移动飞船
ship.moving_left = True
elif event.key == pygame.K_SPACE:
file_bullets(ai_settings, screen, ship, bullets)
elif event.key == pygame.K_p:
if not stats.game_active:
start_game(stats, aliens, bullets, ai_settings, screen, ship)
elif event.key == pygame.K_q:
sys.exit()
def start_game(stats, aliens, bullets, ai_settings, screen, ship):
"""开始游戏"""
#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 check_play_button(stats, play_button, mouse_x, mouse_y, aliens, bullets, ai_settings, screen, ship):
"""在玩家单击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:
start_game(stats, aliens, bullets, ai_settings, screen, ship)
def file_bullets(ai_settings, screen, ship, bullets):
"""发射子弹"""
#创建一颗子弹，并将其加入到编组bullets中
if len(bullets) < ai_settings.bullet_allowed:
new_bullet = Bullet(ai_settings, screen, ship)
bullets.add(new_bullet)
def get_numble_alien_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_width
numble_aliens_x = int(available_space_x / (2 * alien_width))
return numble_aliens_x
def get_numble_rows(ai_settings, ship_height, alien_height):
"""计算屏幕可以存储多少行外星人"""
available_space_y = ai_settings.screen_height - 3 *alien_height - ship_height
nublle_rows = int(available_space_y / (2 * alien_height))
return nublle_rows
def creat_alien(ai_settings, screen, aliens, alien_numble, row_numble):
"""创建一个外星人群，并将其放入当前行"""
alien = Alien(screen, ai_settings)
alien_width = alien.rect.width
alien.x = alien_width + 2 * alien_width * alien_numble
alien.rect.x = alien.x
alien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numble
aliens.add(alien)
def create_fleet(ai_settings, screen, ship, aliens,):
"""创建外星人群"""
"""创建一个外星人，并计算一行可以容纳多少个外星人"""
alien = Alien(screen, ai_settings)
numble_aliens_x = get_numble_alien_x(ai_settings, alien.rect.width)
numble_rows = get_numble_rows(ai_settings, ship.rect.height, alien.rect.height)
#创建第一行外星人
for row_numble in range(numble_rows):
for alien_numble in range(numble_aliens_x):
creat_alien(ai_settings, screen, aliens, alien_numble, row_numble)
def update_screen(ai_settings, screen ,ship, aliens, bullets, stats, play_button):
#每次循环时都会重绘屏幕
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)
#如果游戏处于非激活状态，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):
"""更新子弹位置，并删除已消失的子弹"""
"""更新子弹位置"""
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"""
#删除发生碰撞的外星人
collisions = pygame.sprite.groupcollide(bullets, aliens, False, 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 check_fleet_edges(ai_settings, aliens):
"""有外星人到达边缘时采取措施"""
for alien in aliens.sprites():
if alien.check_edges():
change_fleet_direction(ai_settings, aliens)
break
def change_fleet_direction(ai_settings, aliens):
"""将外星人群下移，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 check_aliens_bottom(ai_settings, stats, screen, ship, bullets, aliens):
"""检查是否有外星人到达了屏幕底端"""
seceen_rect = screen.get_rect()
for alien in aliens:
if alien.rect.bottom >= seceen_rect.bottom:
#像飞船被撞到一样处理
ship_hit(ai_settings, stats, screen, ship, bullets, aliens)
break
def ship_hit(ai_settings, stats, screen, ship, bullets, aliens, ):
"""响应被外星人撞到的飞船"""
if stats.ship_left > 0:
#将ship_left减1
stats.ship_left -= 1
#清空子弹和外星人列表
bullets.empty()
aliens.empty()
#创建一群新外星人
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 update_aliens(ai_settings, stats, screen, ship, bullets, aliens):
"""检查外星人是否在屏幕边缘，并更新外星人群中所有外星人的位置"""
check_fleet_edges(ai_settings, aliens)
aliens.update()
#检测外星人和飞船的碰撞
if pygame.sprite.spritecollideany(ship, aliens):
ship_hit(ai_settings, stats, screen, ship, bullets, aliens)
#检查外星人是否到达屏幕底端
check_aliens_bottom(ai_settings, stats, screen, ship, bullets, aliens)
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"""
self.screen_width = 1200
self.screen_height = 800
self.bg_color = (230, 230, 230)
#飞船的位置
self.ship_speed_factor = 3.5
self.ship_limit = 3
#子弹设置
self.bullet_speed_factor = 3
self.bullet_width = 3
self.bullet_height = 15
self.bullet_color = 60, 60, 60
self.bullet_allowed = 100
#外星人的设置
self.alien_speed_factor = 1
self.fleet_drop_speed = 300
#fleet_direction为1时表示外星人向右移，为-1时表示外星人向左移
self.fleet_direction = 1
game_stats.py
class Gamestats():
"""跟踪游戏统计信息"""
def __init__(self, ai_settings):
"""初始化统计信息"""
self.ai_settings = ai_settings
self.reset_stats()
#游戏刚启动时处于激活状态
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.ship_left = self.ai_settings.ship_limit
button.py
import pygame.font
class Button():
"""初始化按钮的属性"""
def __init__(self, ai_settings, screen, msg):
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.botton_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
#按钮标签只需创建一次
self.prep_meg(msg)
def prep_meg(self, msg):
"""将msg渲染为图像，并使其有按钮上居中"""
self.msg_image = self.font.render(msg, True, self.text_color)
self.msg_image_rect = self.msg_image.get_rect()
self.msg_image_rect.center = self.rect.center
def draw_button(self):
"""创建一个用颜色填充的按钮，再绘制文本"""
self.screen.fill(self.botton_color, self.rect)
self.screen.blit(self.msg_image, self.msg_image_rect)
ship.py
import pygame
class Ship():
"""初始化飞船并设置其初始位置"""
def __init__(self, screen, ai_settings):
self.screen = screen
self.ai_settings = ai_settings
#加载飞船图像并获取其外形矩形
self.image = pygame.image.load("images/ship.bmp")
self.rect = self.image.get_rect()
self.screen_rect = self.screen.get_rect()
#将每艘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位置"""
"""更新飞船的center值，而不是更新rect值"""
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 > self.screen_rect.left:
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)
def center_ship(self):
"""让飞船在屏幕上居中"""
self.center = self.screen_rect.centerx
alien.py
import pygame
from pygame.sprite import Sprite
class Alien(Sprite):
"""表示单个外星人的类"""
def __init__(self, screen, ai_settings):
"""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
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
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 blitem(self):
"""在屏幕上绘制外星人"""
self.screen.blit(self.image, self.rect)
def check_edges(self):
"""如果外星人到达屏幕边缘就返回True"""
screen_rect = self.screen.get_rect()
if self.rect.right >= screen_rect.right or self.rect.left <= 0:
return True
def update(self):
"""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
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):
super(Bullet, self).__init__()
self.screen = screen
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
#存储用小数表示子弹的位置
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"""
self.y -= self.speed_factor
#更新子弹位置的小数值
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)