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.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起始位置"""
super(Alien, self).__init__()
self.screen=screen
self.ai_settings=ai_settings
"""加载外星人照片，设置rect值"""
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的左上角附近"""
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):
self.screen.blit(self.image,self.rect)
def check_edge(self):
"""如果外星人位于屏幕边缘，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):
self.x+=(self.ai_settings.alien_speed_factor *
self.ai_settings.fleet_direction)
self.rect.x=self.x
#alien_invision.py
import pygame
from settings import Settings
from ship import Ship
import game_functions as gf
from pygame.sprite import Group
from game_stats import GameStats
from button import Button
def run_game():
#初始化游戏并创建一个屏幕对象
pygame.init()
ai_settings=Settings()
#子弹组
bullets=Group()
aliens=Group()
screen=pygame.display.set_mode(
(ai_settings.screen_width,ai_settings.screen_height))
#创建一艘飞船
ship=Ship(ai_settings,screen)
gf.create_fleet(ai_settings,screen,ship,aliens)
pygame.display.set_caption("Alien Invision")
#创建Play按钮
play_button=Button(screen,'Play')
#创建一个存储游戏统计信息的实例
stats=GameStats(ai_settings)
while True:
#监听鼠标和键盘事件
gf.check_event(ai_settings,screen,ship,bullets,stats, play_button)
if stats.game_active:
ship.update()
gf.update_bullets(bullets,ai_settings,screen,ship,aliens)
gf.update_aliens(ai_settings,aliens,ship,stats, screen, bullets)
gf.update_screen(ai_settings,screen,ship,aliens,bullets,stats,play_button)
run_game()
#game_stats.py
class GameStats():
def __init__(self,ai_settings):
self.ai_settings=ai_settings
self.reset_stats()
self.game_active=False
def reset_stats(self):
self.ship_left=self.ai_settings.ship_limit
#button.py
import pygame;
class Button():
def __init__(self,screen,msg):
"""初始化按钮属性"""
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=(0,255,0)
self.text_color=(255,255,255)
self.font=pygame.font.SysFont(None,48)
#创建按钮的rect对象，并使它居中
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渲染橙图像，并使它在按钮上居中(文本颜色，背景色)"""
self.mag_image=self.font.render(msg,True,self.text_color,self.button_color)
self.mag_rect=self.mag_image.get_rect()
self.mag_rect.center=self.rect.center
def draw_button(self):
"""绘制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.mag_image,self.mag_rect)
#game_function.py
import pygame
import sys
from bullet import Bullet
from alien import Alien
from time import sleep
from button import Button
#函数check_events() 不需要任何形参
def check_event(ai_settings,screen,ship,bullets,stats, play_button):
"""响应键盘和鼠标事件"""
for event in pygame.event.get():
if event.type==pygame.QUIT:
sys.exit()
elif event.type == pygame.KEYDOWN:
check_keydown_events(event,ai_settings,screen,ship,bullets, stats)
elif event.type == pygame.KEYUP:
check_keyup_event(event, ship)
elif event.type==pygame.MOUSEBUTTONDOWN:
#pygame.mouse.get_pos() ，它返回一个元组，其中包含玩家单击时鼠标的x 和y 坐标
mouse_x,mouse_y=pygame.mouse.get_pos()
check_play_button(stats, play_button, mouse_x, mouse_y)
def check_play_button(stats,play_button,mouse_x,mouse_y):
"""在玩家单击Play按钮时开始新游戏"""
#将这些值传递给函数check_play_button()，而这个函数使用collidepoint()
# 检查鼠标单击位置是否在Play按钮的rect 内
start_game(play_button, mouse_x, mouse_y, stats)
def start_game(play_button,mouse_x,mouse_y,stats):
if play_button.rect.collidepoint(mouse_x,mouse_y):
stats.game_active=True
def check_keydown_events(event,ai_settings,screen,ship,bullets,stats):
if event.key == pygame.K_RIGHT:
ship.moving_right = True
if event.key == pygame.K_LEFT:
ship.moving_left = True
if event.key == pygame.K_SPACE:
fire_bullets(ai_settings, screen, ship, bullets)
if event.key==pygame.K_p:
stats.game_active = True
elif event.key==pygame.K_q:
sys.exit()
def check_keyup_event(event,ship):
if event.key == pygame.K_RIGHT:
ship.moving_right = False
if event.key == pygame.K_LEFT:
ship.moving_left = False
def update_screen(ai_settings,screen,ship,aliens,bullets,stats,play_button):
#每次循环时重新绘制屏幕，背景色填充屏幕
screen.fill(ai_settings.bg_color)
for bullet in bullets:
bullet.draw_bullet()
ship.blitme()
aliens.draw(screen)
#如果游戏处于非活动状态，就会显示Play按钮
if stats.game_active==False:
play_button.draw_button()
#显示新屏幕
pygame.display.flip()
def update_bullets(bullets,ai_settings,screen,ship,aliens):
bullets.update()
for bullet in bullets.copy():
if bullet.rect.bottom < 0:
bullets.remove(bullet)
check_bullet_alien_collisions(bullets, aliens, ai_settings, screen, ship)
def check_bullet_alien_collisions(bullets,aliens,ai_settings,screen,ship):
# 检查是否有子弹击中了外星人
# 如果是这样，就删除相应的子弹和外星人
colisions = pygame.sprite.groupcollide(bullets, aliens, True, True)
# 删除现有的子弹并新建一群外星人
if len(aliens) == 0:
bullets.empty()
create_fleet(ai_settings, screen, ship, aliens)
def fire_bullets(ai_settings,screen, ship,bullets):
if len(bullets) < ai_settings.bullets_allowed:
bullet = Bullet(ai_settings, screen, ship)
bullets.add(bullet)
def get_number_rows(ai_settings,ship_height,alien_height):
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 get_number_aliens_x(ai_settings,alien_width):
available_space_x = ai_settings.screen_width - 2 * alien_width
number_aliens_x = int(available_space_x / (2 * alien_width))
return number_aliens_x
def create_alien(ai_settings,screen,aliens,alien_number,row_number):
alien = Alien(ai_settings, screen)
alien_width=alien.rect.width
alien_height=alien.rect.height
alien.x = alien_width + 2 * alien_width * alien_number
alien.y=alien_height+2*alien_height*row_number
alien.rect.x = alien.x
alien.rect.y=alien.y
aliens.add(alien)
def create_fleet(ai_settings,screen,ship,aliens):
"""创建外星人群"""
#创建一个外星人，计算一行可以容纳多少个外星人
#外星人的间距就是外星人的宽度
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)
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_edge(ai_settings,aliens):
for alien in aliens:
if alien.check_edge():
change_fleet_direction(ai_settings,aliens)
break
def change_fleet_direction(ai_settings,aliens):
"""将全部外星人下移，并改变他们的方向"""
for alien in aliens.sprites():
alien.rect.y+=ai_settings.fleet_drop_speed
ai_settings.fleet_direction *= -1
def update_aliens(ai_settings,aliens,ship,stats, screen, bullets):
check_fleet_edge(ai_settings,aliens)#纵向位置变化
aliens.update()#横向位置变化
"""检查外星人位置变化后是不是和飞船撞了"""
if pygame.sprite.spritecollideany(ship,aliens):
ship_hit(stats, ai_settings, aliens, screen, bullets, ship)
check_aliens_bottom(stats,ai_settings,aliens,screen,bullets,ship)
def check_aliens_bottom(stats,ai_settings,aliens,screen,bullets,ship):
"""检查是否有外星人撞到了屏幕底端"""
screen_rect=screen.get_rect()
for alien in aliens.sprites():
if alien.rect.bottom>screen_rect.bottom:
ship_hit(stats,ai_settings,aliens,screen,bullets,ship)
break
def ship_hit(stats,ai_settings,aliens,screen,bullets,ship):
"""飞船被撞，减一"""
if stats.ship_left>0:
stats.ship_left -= 1
"""清空外星人和子弹"""
aliens.empty()
bullets.empty()
"""创建一群外星人，把飞船放到屏幕底部中央位置"""
create_fleet(ai_settings, screen, ship, aliens)
ship.center_ship()
"""暂停"""
sleep(0.5)
else:
stats.game_active=False
#ship.py
import pygame
class Ship():
def __init__(self,ai_settings,screen):
"""初始化飞船并且设置它的初始位置"""
self.screen=screen
self.ai_settings=ai_settings
"""加载飞船图像并获取表示图像的矩形"""
self.image=pygame.image.load("images/ship.bmp")
self.rect=self.image.get_rect()
self.screen_rect=screen.get_rect()
"""将每一艘新飞船放在屏幕底部的中央"""
self.rect.centerx=self.screen_rect.centerx
self.rect.bottom=self.screen_rect.bottom
self.center=float(self.rect.centerx)
self.moving_right=False
self.moving_left=False
def blitme(self):
self.screen.blit(self.image,self.rect)
def update(self):
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
def center_ship(self):
self.center=self.screen_rect.centerx
#settings.py
class Settings():
#存储“外星人入侵的”所有的设置类
def __init__(self):
self.screen_width=1200
self.screen_height=700
self.bg_color=(230,230,230)
self.ship_speed_factor=1.5
self.ship_limit = 3
"""子弹"""
self.bullet_speed_factor=3
self.bullet_color=60,60,60
self.bullet_height=15
self.bullet_width=300
self.bullets_allowed=5
"""外星人"""
self.alien_speed_factor=1
self.fleet_drop_speed=30
#fleet_direction为1表示向右移，为-1表示向左移
self.fleet_direction=1
#bullet.py
import pygame
from pygame.sprite import Sprite
class Bullet(Sprite):
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
"""存储子弹位置"""
self.y=float(self.rect.y)
self.color=ai_settings.bullet_color
self.speed_factor=ai_settings.bullet_speed_factor
def update(self):
self.y-=self.speed_factor
self.rect.y=self.y
def draw_bullet(self):
pygame.draw.rect(self.screen,self.color,self.rect)
