Python pygame库的应用

今天想用pygame库写一个击打外星人飞船的python程序

这个游戏的效果是操纵一个位于屏幕底端的飞船，通过上下左右控制飞船移动方向，按空格发射子弹。游戏中击杀一批飞船后进入下一关卡。每一关卡击打飞船获得的得分递增。若外星飞船触碰飞船或屏幕底端则减一条命。最终计算总得分。

游戏中主要包括了：飞船对象，alien对象，子弹对象，游戏设置，游戏状态，游戏控制按钮，计分板。

1.飞船部分

由于pygame中已有sprite类，故飞船可直接继承sprite类
注意在继承类时class中标注继承了什么类，_ _init_ _函数中要使用super(Ship,self).__init__()来完成继承工作。同时init中也引入了ai—setting和screen（这些部分的代码会在后面写出）

然后为了构建这个飞船的形态，需要在当前文件夹中保存一个飞船的图像。初始化时设置飞船矩形（rect）的中心与游戏界面的中心位于同一垂直线上，飞船底部位于屏幕底端。初始化时定义四个位移变量（上下左右）并设置为false，以便后面按键时对其进行改变。
接下来定义了update函数，这个函数的作用是改变飞船的当前状态，如按下←键时使得飞船左移。同时需要注意：飞船的左侧不能超过屏幕的左端，否则会很影响游戏体验。其余同理。
然后是blitme函数，这个函数完成了将飞船状态及时更新在屏幕上的工作。
最后写了一个centership函数，是用来在需要的时刻将飞船重新放置到屏幕中央。

 import pygame
 from pygame.sprite import Sprite

 class Ship(Sprite):#继承sprite类

 def __init__(self,ai_settings,screen):
 super(Ship,self).__init__()
 self.screen=screen
 self.ai_settings=ai_settings

 self.image=pygame.image.load('images/ship.bmp')
 self.rect=self.image.get_rect()
 self.screen_rect=screen.get_rect()

 self.rect.centerx=self.screen_rect.centerx
 self.rect.bottom=self.screen_rect.bottom

 self.center=float(self.rect.centerx)
 self.high=float(self.rect.bottom)

 self.moving_right=False
 self.moving_left=False
 self.moving_up=False
 self.moving_down=False

 def update(self):
 if self.moving_right and self.rect.right<self.screen_rect.right:
 #self.rect.centerx+=1
 self.center+=self.ai_settings.ship_speed_factor_horizen
 if self.moving_left and self.rect.left>self.screen_rect.left:
 #self.rect.centerx-=1
 self.center-=self.ai_settings.ship_speed_factor_horizen
 if self.moving_up and self.rect.top>self.screen_rect.top:

 self.high-=self.ai_settings.ship_speed_factor_height
 if self.moving_down and self.rect.bottom<self.screen_rect.bottom:

 self.high+=self.ai_settings.ship_speed_factor_height

 self.rect.centerx=self.center
 self.rect.bottom=self.high

 def blitme(self):

 self.screen.blit(self.image,self.rect)
 def center_ship(self):
 self.center=self.screen_rect.centerx

(ship)

给出alien部分：
alien部分生成了飞船群
然后为了产生初始的随机方向飞行，引入了random库。
同样的，这里的alien也继承了Sprite精灵。
注意，这里的飞船图像必须保存在当前文件夹下，然后用pygame.load来加载图片。
一个细节，由于alien移动距离是浮点型，所以要先计算移动的浮点类型，最后将其转换成整形以保证移动的连续性。同时由于alien图像必须保证一直处在screen内，所以这里定义了一个方法check_edges，通过self.screen.get_rect()来获取屏幕的位置，将alien与screen都视为矩形，比较两者的边界即可。

 import pygame
 import random##########
 from pygame.sprite import Sprite

 class Alien(Sprite):

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

 self.rect.x=self.rect.width#-20
 self.rect.y=self.rect.height#-20

 self.direction=random.choice([1,-1])

 self.x=float(self.rect.x)

 def check_edges(self):
 screen_rect=self.screen.get_rect()
 if self.rect.right>=screen_rect.right:
 return True
 elif self.rect.left<=screen_rect.left:
 return True

 def blitme(self):
 self.screen.blit(self.image,self.rect)

 def update(self):
 #由于x可以精确到小数，故先更新x，再用x更新rect
 self.x+=(self.ai_settings.alien_speed_factor*
 self.direction)#*random.choice([1,-1])#####
 self.rect.x=self.x

(alien)

给出bullet部分。
bullet同ship，alien一样，也继承了sprite。
注意，由于子弹是由飞船从飞船上部发出，故初始化子弹时要将其位置设置在飞船上部中央，子弹大小也不能过大。因为子弹大小较小，所以用pygame中的draw.rect(self.screen,self.color,self.rect)来画出一个小矩形即可，这种方法比较省事。如果想要使子弹的形状更加美观，可以用上面ship和alien中加载位图的方式。

 import pygame
 from pygame.sprite import Sprite

 class Bullet(Sprite):

 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.bottom=ship.rect.bottom

 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)

(bullet)

给出游戏设置部分。
我们把游戏中所有涉及数据的部分都放在这个文件中，包括了屏幕，速度，子弹，飞船，外星人，游戏节奏以及游戏关卡更新。

 class Settings():
 """存储所有设置的类"""
 def __init__(self):
 self.high_score=0

 #屏幕设置
 self.screen_width=1200
 self.screen_height=650
 self.bg_color=(230,230,230)
 #速度设置
 self.ship_speed_factor_horizen=1
 self.ship_speed_factor_height=0.5
 self.ship_limit=3

 #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

 #外星人设置
 self.alien_speed_factor=1
 self.fleet_drop_speed=10
 #direction为1表示右移，-1表示左移
 self.fleet_direction=1
 self.alien_points=50

 #游戏节奏设置
 self.speedup_scale=1.1
 self.score_scale=1.5

 self.initialize_dynamic_settings()

 def initialize_dynamic_settings(self):
 self.ship_speed_factor=1.5
 self.bullet_speed_factor=3
 self.alien_speed_factor=1

 self.fleet_direction=1

 def increase_speed(self):
 self.ship_speed_factor*=self.speedup_scale
 self.bullet_speed_factor*=self.speedup_scale
 self.alien_speed_factor*=self.speedup_scale

 self.alien_points=int(self.alien_points*self.score_scale)

(settings)

给出游戏状态部分。
将游戏中的状态部分都放置在这个文件中。

 class GameStats():
 def __init__(self,ai_settings):
 self.ai_settings=ai_settings
 self.reset_stats()
 self.game_active=False

 self.high_score=0

 def reset_stats(self):

 self.ships_left=self.ai_settings.ship_limit
 self.score=0
 self.level=1

(state)

由于游戏初始通常有一个START按钮用于开始游戏，所以这里需要定义一个按钮类。这里需要引入pygame.font用于其中的字体部分。
loading.......

 import pygame.font

 class Button():

 def __init__(self,ai_settings,screen,message):
 '''初始化按钮的属性'''
 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_message(message)

 def prep_message(self,message):
 #图像渲染
 self.message_image=self.font.render(message,True,self.text_color,
 self.button_color)
 self.message_image_rect=self.message_image.get_rect()
 self.message_image_rect.center=self.rect.center

 def draw_button(self):
 self.screen.fill(self.button_color,self.rect)
 self.screen.blit(self.message_image,self.message_image_rect)

(button)

给出计分板部分：

 import pygame.font
 from pygame.sprite import Group

 from ship import Ship

 class Scoreboard():

 def __init__(self,ai_settings,screen,stats):
 self.screen=screen
 self.screen_rect=screen.get_rect()
 self.ai_settings=ai_settings
 self.stats=stats

 self.text_color=(30,30,30)
 self.font=pygame.font.SysFont(None,48)

 self.prep_score()
 self.prep_high_score()
 self.prep_history_high_score()##########
 self.prep_level()
 self.prep_ships()

 def prep_score(self):
 '''将得分渲染成图像'''
 rounded_score=int(round(self.stats.score,-1))
 score_str="score:"+"{:,}".format(rounded_score)
 self.score_image=self.font.render(score_str,True,self.text_color,
 self.ai_settings.bg_color)

 #将得分放在右上角
 self.score_rect=self.score_image.get_rect()
 self.score_rect.right=self.screen_rect.right-20
 self.score_rect.top=20#存疑

 def prep_high_score(self):
 high_score=int(round(self.stats.high_score,-1))
 high_score_str="High score:"+"{:,}".format(high_score)
 self.high_score_image=self.font.render(high_score_str,True,
 self.text_color,self.ai_settings.bg_color)
 self.high_score_rect=self.high_score_image.get_rect()
 self.high_score_rect.centerx=self.screen_rect.centerx-195
 self.high_score_rect.top=self.score_rect.top

 def prep_history_high_score(self):###########
 with open("highscore.txt") as file1:
 lines=file1.readlines()
 temp_string=''
 for line in lines:
 temp_string+=line.rstrip()
 history_high_score=eval(temp_string)
 history_high_score_str="Highest score:"+"{:,}".format(history_high_score)
 self.history_high_score_image=self.font.render(history_high_score_str,
 True,self.text_color,self.ai_settings.bg_color)
 self.history_high_score_rect=self.history_high_score_image.get_rect()
 self.history_high_score_rect.left=self.high_score_rect.right+45
 self.history_high_score_rect.top=self.high_score_rect.top

 def prep_level(self):
 self.level_image=self.font.render("Level:"+str(self.stats.level),True,
 self.text_color,self.ai_settings.bg_color)
 '''将等级放在得分下方'''
 self.level_rect=self.level_image.get_rect()
 self.level_rect.right=self.score_rect.right
 self.level_rect.top=self.score_rect.bottom+10

 def prep_ships(self):
 self.ships=Group()
 for ship_number in range(self.stats.ships_left):
 ship=Ship(self.ai_settings,self.screen)
 ship.rect.x=10+ship_number*ship.rect.width
 ship.rect.y=10
 self.ships.add(ship)

 def show_score(self):
 self.screen.blit(self.score_image,self.score_rect)
 self.screen.blit(self.high_score_image,self.high_score_rect)
 self.screen.blit(self.history_high_score_image,
 self.history_high_score_rect)####
 self.screen.blit(self.level_image,self.level_rect)
 self.ships.draw(self.screen)

(scoreboard)

给出游戏中用到的各种函数部分：

 import sys
 import pygame
 import random
 import time
 from bullet import Bullet
 from alien import Alien
 from time import sleep

 def check_keydown_events(event,ai_settings,stats,screen,ship,bullets):#stats
 if event.key==pygame.K_RIGHT:
 #向右移动一格
 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_bullets(ai_settings,screen,ship,bullets)
 elif event.key==pygame.K_q:#按q键退出界面
 renew_history_high_score(stats)###########
 pygame.quit()
 sys.exit()

 def check_keyup_events(event,ship):
 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

 def fire_bullets(ai_settings,screen,ship,bullets):
 if len(bullets)<ai_settings.bullets_allowed:

 new_bullet=Bullet(ai_settings,screen,ship)
 bullets.add(new_bullet)

 def check_events(ai_settings,screen,stats,sb,play_button,ship,aliens,
 bullets):

 for event in pygame.event.get():

 if event.type==pygame.QUIT:
 renew_history_high_score(stats)###########
 pygame.quit()
 sys.exit()

 elif event.type==pygame.KEYDOWN:
 check_keydown_events(event,ai_settings,stats,screen,ship,bullets)
 ##########stats
 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,sb,play_button,ship,
 aliens,bullets,mouse_x,mouse_y)

 def check_play_button(ai_settings,screen,stats,sb,play_button,ship,aliens,
 bullets,mouse_x,mouse_y):
 button_clicked=play_button.rect.collidepoint(mouse_x,mouse_y)
 if button_clicked and not stats.game_active:
 ai_settings.initialize_dynamic_settings()
 #隐藏光标
 pygame.mouse.set_visible(False)
 #重置统计信息
 stats.reset_stats()
 stats.game_active=True
 #重置记分牌图像
 sb.prep_score()
 sb.prep_high_score()
 sb.prep_level()
 sb.prep_ships()

 #清空外星人和子弹
 aliens.empty()
 bullets.empty()

 create_fleet(ai_settings,screen,ship,aliens)
 ship.center_ship()

 def update_screen(ai_settings,screen,stats,sb,ship,aliens,bullets,play_button):

 screen.fill(ai_settings.bg_color)
 for bullet in bullets.sprites():
 bullet.draw_bullet()
 ship.blitme()
 #alien.blitme
 aliens.draw(screen)
 sb.show_score()
 #如果处于非活动状态，绘制Play按钮
 if not stats.game_active:
 play_button.draw_button()
 pygame.display.flip()

 def check_bullet_alien_collisions(ai_settings,screen,stats,sb,
 ship,aliens,bullets):
 collisions=pygame.sprite.groupcollide(bullets,aliens,True,True)
 if collisions:
 for aliens in collisions.values():
 stats.score+=ai_settings.alien_points*len(aliens)
 #每个值都是一个列表!!!
 sb.prep_score()
 check_high_score(stats,sb)
 if len(aliens)==0:

 bullets.empty()
 ai_settings.increase_speed()
 stats.level+=1
 sb.prep_level()
 create_fleet(ai_settings,screen,ship,aliens)

 def update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets):
 bullets.update()

 for bullet in bullets.copy():
 if bullet.rect.bottom<=0:
 bullets.remove(bullet)
 #碰撞后返回一个字典
 check_bullet_alien_collisions(ai_settings,screen,stats,sb,
 ship,aliens,bullets)

 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 get_number_rows(ai_settings,ship_height,alien_height):
 ''''计算屏幕可容纳行数'''
 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):
 alien=Alien(ai_settings,screen)
 alien_width=alien.rect.width
 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'''
 #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)
 total_alien_number=number_aliens_x*number_rows
 for row_number in range(number_rows):
 for alien_number in range(number_aliens_x):
 #创建一个外星人并将其加入当前行
 create_alien(ai_settings,screen,aliens,alien_number,
 row_number)

 def change_fleet_direction(ai_settings,aliens):
 for alien in aliens.sprites():
 alien.rect.y+=ai_settings.fleet_drop_speed
 ai_settings.fleet_direction*=-1########

 def ship_hit(ai_settings,stats,sb,screen,ship,aliens,bullets):
 if stats.ships_left>0:

 stats.ships_left-=1
 sb.prep_ships()
 aliens.empty()
 bullets.empty()

 create_fleet(ai_settings,screen,ship,aliens)
 ship.center_ship()

 sleep(0.5)
 else:
 stats.game_active=False
 pygame.mouse.set_visible(True)

 def check_aliens_bottom(ai_settings,stats,sb,screen,ship,aliens,bullets):
 screen_rect=screen.get_rect()
 for alien in aliens.sprites():
 if alien.rect.bottom>=screen_rect.bottom:
 ship_hit(ai_settings,stats,sb,screen,ship,aliens,bullets)
 break

 def check_fleet_edges(ai_settings,aliens):
 for alien in aliens.sprites():
 if alien.check_edges():
 #change_fleet_direction(ai_settings,aliens)
 #break
 alien.direction*=-1#random.choice([1,-1])
 alien.rect.y+=ai_settings.fleet_drop_speed

 #def change_alien_direction()

 def check_time(ai_settings,aliens):
 now=time.time()
 running_time=int(now-start)
 if running_time==1:
 for alien in aliens.sprites():
 alien.direction*=-1#random.choice([1,-1])
 alien.rect.y+=ai_settings.fleet_drop_speed

 def update_aliens(ai_settings,stats,sb,screen,ship,aliens,bullets):
 #check_time(start,ai_settings,aliens)
 check_fleet_edges(ai_settings,aliens)
 #check_time(ai_settings,aliens)
 aliens.update()

 if pygame.sprite.spritecollideany(ship,aliens):
 ship_hit(ai_settings,stats,sb,screen,ship,aliens,bullets)
 check_aliens_bottom(ai_settings,stats,sb,screen,ship,aliens,bullets)

 def check_high_score(stats,sb):
 if stats.score>stats.high_score:
 stats.high_score=stats.score
 sb.prep_high_score()

 def renew_history_high_score(stats):##########
 filename='highscore.txt'
 with open(filename) as file_object:
 lines=file_object.readlines()
 temp_string=''
 for line in lines:
 temp_string+=line.rstrip()
 if stats.high_score>eval(temp_string):
 with open(filename,'w') as file:
 file.write(str(stats.high_score))

最后给出程序的主要部分
主要部分中引入了pygame ，time以及Group
创建了 飞船对象，alien对象，子弹对象，游戏设置，游戏状态，游戏控制按钮，计分板。

 """
 待加入项目:
 1.引入历史最高分 ### 已完成
 2.加入随机飞行系统 ### 基本完成/衰
 """

 import pygame
 import time
 from pygame.sprite import Group
 from game_stats import GameStats

 from settings import Settings
 from ship import Ship
 from alien import Alien
 from button import Button
 from scoreboard import Scoreboard
 import game_functions as gf

 def run_game():
 #初始化对象并创建一个屏幕对象
 pygame.init() #初始化
 ai_settings=Settings()
 screen=pygame.display.set_mode((
 ai_settings.screen_width,ai_settings.screen_height))
 pygame.display.set_caption("Alien Invasion")
 #创建一个按钮
 play_button=Button(ai_settings,screen,'Play')
 ship=Ship(ai_settings,screen)#创建一个飞船 

 #创建一个子弹编组
 bullets=Group()
 aliens=Group()
 bg_color=(230,230,230)
 alien=Alien(ai_settings,screen)
 gf.create_fleet(ai_settings,screen,ship,aliens)
 #创建存储游戏统计信息的实例，并创建记分牌
 stats=GameStats(ai_settings)
 sb=Scoreboard(ai_settings,screen,stats)
 #start=time.time()
 while True:

 #监视键盘和鼠标事件
 gf.check_events(ai_settings,screen,stats,sb,play_button,ship,aliens,
 bullets)
 if stats.game_active:
 ship.update()
 gf.update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets)
 gf.update_aliens(ai_settings,stats,sb,screen,ship,aliens,bullets)
 gf.update_screen(ai_settings,screen,stats,sb,ship,aliens,bullets,
 play_button)

 run_game()
 chenk_events部分检测了鼠标以及键盘按键