前言

前一段时间借到了一本史诗般的Python教程，Eric Matthes编著的《Python编程：从入门到实践》。其中第一个实例，利用Pygame制作《外星人入侵》小游戏的项目深深吸引了我。

该游戏原理很简单，就是在一个窗口上面生成很多外星人飞船，玩家需要操控最下面的角色左右移动并发射子弹消灭这些外星人。外星人每碰到左右边框一次便向下移动一点，移动到底的时候游戏便失败了。 每消灭一组外星人生成一组新的外星人，同时速度更快，得分倍率更高。

照着书上的做法一步一步来，最终果然写出了像样的程序。为纪念这一成果，将代码记录于此。由于本人比较懒，代码注释就不放了，不过一般都能看得懂~

当然，CSDN上有很多类似的文章，但我还是将它发了出来。毕竟自己做一遍，和看别人的是完全不一样的感觉呢！

（成果图就不放了_(:з」∠)_）

启动程序：alien_invasion.py

import pygame
import sys
import time
from pygame.sprite import Group
from settings import Settings
from ship import Ship
from alien import Alien
from game_stats import GameStats
from scoreboard import Scoreboard
from button import Button
import game_functions as gf
def run_game():pygame.init()ai_settings = Settings()screen = pygame.display.set_mode((ai_settings.screen_width,ai_settings.screen_height))pygame.display.set_caption("Alien Invasion")play_button = Button(ai_settings,screen,"> Play <")stats = GameStats(ai_settings)sb = Scoreboard(ai_settings,screen,stats)ship = Ship(ai_settings,screen)bullets = Group()aliens = Group()gf.create_fleet(ai_settings,screen,ship,aliens)while True:time.sleep(0.02)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,screen,stats,sb,ship,aliens,bullets)gf.update_screen(ai_settings,screen,stats,sb,ship,aliens,bullets,play_button)
run_game()

玩家飞船设定：ship.py

import pygame
from pygame.sprite import Sprite
class Ship(Sprite):def __init__(self,ai_settings,screen):super(Ship,self).__init__()self.screen = screenself.ai_settings = ai_settingsself.image = pygame.image.load('image/ship.bmp')self.rect = self.image.get_rect()self.screen_rect = screen_rect = screen.get_rect()self.rect.centerx = self.screen_rect.centerxself.rect.bottom = self.screen_rect.bottomself.center = float(self.rect.centerx)self.moving_right = Falseself.moving_left = Falsedef update(self):if self.moving_right and self.rect.right < self.screen_rect.right:self.center+=self.ai_settings.ship_speed_factorif self.moving_left and self.rect.left > 0:self.center-=self.ai_settings.ship_speed_factorself.rect.centerx = self.centerdef blitme(self):self.screen.blit(self.image,self.rect)def center_ship(self):self.center = self.screen_rect.centerx

外星人飞船设定：alien.py

import pygame
from pygame.sprite import Sprite
class Alien(Sprite):def __init__(self,ai_settings,screen):super(Alien,self).__init__()self.screen = screenself.ai_settings = ai_settingsself.image = pygame.image.load('image/alien.bmp')self.rect = self.image.get_rect()self.rect.x = self.rect.widthself.rect.y = self.rect.heightself.x = float(self.rect.x)def blitme(self):self.screen.blit(self.image,self.rect)def check_edges(self):screen_rect = self.screen.get_rect()if self.rect.right >= screen_rect.right:return Trueelif self.rect.left <= 0:return Truedef update(self):self.x+=(self.ai_settings.alien_speed_factor * self.ai_settings.fleet_direction)self.rect.x = self.x

子弹设定：bullet.py

import pygame
from pygame.sprite import Spriteclass Bullet(Sprite):def __init__(self,ai_settings,screen,ship):super(Bullet,self).__init__()self.screen = screenself.rect = pygame.Rect(0,0,ai_settings.bullet_width,ai_settings.bullet_height)self.rect.centerx = ship.rect.centerxself.rect.top = ship.rect.topself.y = float(self.rect.y)self.color = ai_settings.bullet_colorself.speed_factor = ai_settings.bullet_speed_factordef update(self):self.y-=self.speed_factorself.rect.y = self.ydef draw_bullet(self):pygame.draw.rect(self.screen,self.color,self.rect)

游戏开始按钮设定：button.py

import pygame.font
class Button():def __init__(self,ai_settings,screen,msg):self.screen = screenself.screen_rect = screen.get_rect()self.width,self.height = 200,50self.button_color = (0,0,255)self.text_color = (255,255,255)self.font = pygame.font.SysFont("Arial",36,True)self.rect = pygame.Rect(0,0,self.width,self.height)self.rect.center = self.screen_rect.centerself.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.centerdef draw_button(self):self.screen.fill(self.button_color,self.rect)self.screen.blit(self.msg_image,self.msg_image_rect)

游戏逻辑设定：game_functions.py

import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleep
def check_keydown_events(event,ai_settings,screen,ship,bullets):if event.key == pygame.K_RIGHT:ship.moving_right = Trueelif event.key == pygame.K_LEFT:ship.moving_left = Trueelif event.key == pygame.K_SPACE:fire_bullet(ai_settings,screen,ship,bullets)elif event.key == pygame.K_q:sys.exit()def check_keyup_events(event,ship):pygame.time.delay(10)if event.key == pygame.K_RIGHT:ship.moving_right = Falseelif event.key == pygame.K_LEFT:ship.moving_left = Falsedef check_events(ai_settings,screen,stats,sb,play_button,ship,aliens,bullets):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)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()pygame.mouse.set_visible(False)stats.reset_stats()stats.game_active = Truesb.prep_score()sb.prep_high_score()sb.prep_level()sb.prep_ships()aliens.empty()bullets.empty()create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()def fire_bullet(ai_settings,screen,ship,bullets):if len(bullets) < ai_settings.bullets_allowed:new_bullet = Bullet(ai_settings,screen,ship)bullets.add(new_bullet)def update_screen(ai_settings,screen,stats,sb,ship,alien,bullets,play_button):screen.fill(ai_settings.bg_color)for bullet in bullets.sprites():bullet.draw_bullet()ship.blitme()alien.draw(screen)sb.show_score()if not stats.game_active:play_button.draw_button()pygame.display.flip()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)check_bullet_alien_collisions(ai_settings,screen,stats,sb,ship,aliens,bullets)def update_aliens(ai_settings,screen,stats,sb,ship,aliens,bullets):check_fleet_edges(ai_settings,aliens)aliens.update()if pygame.sprite.spritecollideany(ship,aliens):ship_hit(ai_settings,screen,stats,sb,ship,aliens,bullets)check_aliens_bottom(ai_settings,screen,stats,sb,ship,aliens,bullets)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_pointssb.prep_score()check_high_score(stats,sb)if len(aliens) == 0:bullets.empty()ai_settings.increase_speed()stats.level+=1sb.prep_level()create_fleet(ai_settings,screen,ship,aliens)def check_fleet_edges(ai_settings,aliens):for alien in aliens.sprites():if alien.check_edges():change_fleet_direction(ai_settings,aliens)breakdef change_fleet_direction(ai_settings,aliens):for alien in aliens.sprites():alien.rect.y+=ai_settings.fleet_drop_speedai_settings.fleet_direction*=-1def ship_hit(ai_settings,screen,stats,sb,ship,aliens,bullets):if stats.ships_left > 0:stats.ships_left-=1sb.prep_ships()aliens.empty()bullets.empty()create_fleet(ai_settings,screen,ship,aliens)ship.center_ship()sleep(1)else:stats.game_active = Falsepygame.mouse.set_visible(True)def check_aliens_bottom(ai_settings,screen,stats,sb,ship,aliens,bullets):screen_rect = screen.get_rect()for alien in aliens.sprites():if alien.rect.bottom >= screen_rect.bottom:ship_hit(ai_settings,screen,stats,sb,ship,aliens,bullets)breakdef get_number_aliens_x(ai_settings,alien_width):available_space_x = ai_settings.screen_width - 2 * alien_widthnumber_aliens_x = int(available_space_x / (2 * alien_width))return number_aliens_xdef 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_rowsdef create_alien(ai_settings,screen,aliens,alien_number,row_number):alien = Alien(ai_settings,screen)alien_width = alien.rect.widthalien.x = alien_width + 2 * alien_width * alien_numberalien.rect.x = alien.xalien.rect.y = alien.rect.height + 2 * alien.rect.height * row_numberaliens.add(alien)def create_fleet(ai_settings,screen,ship,aliens):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_high_score(stats,sb):if stats.score > stats.high_score:stats.high_score = stats.scoresb.prep_high_score()

游戏统计设定：game_stats.py

from settings import Settings
class GameStats():def __init__(self,ai_settings):self.ai_settings = ai_settingsself.reset_stats()self.game_active = Falseself.high_score = 0self.level = 1def reset_stats(self):self.ships_left = self.ai_settings.ship_limitdef reset_stats(self):self.ships_left = self.ai_settings.ship_limitself.score = 0self.level=1

计分板设定：scoreboard.py

import pygame.font
from pygame.sprite import Group
from ship import Ship
class Scoreboard():def __init__(self,ai_settings,screen,stats):self.screen = screenself.screen_rect = screen.get_rect()self.ai_settings = ai_settingsself.stats = statsself.text_color = (255,0,255)self.font = pygame.font.SysFont("Arial",28,True)self.prep_score()self.prep_high_score()self.prep_level()self.prep_ships()def prep_score(self):pstr = str(self.stats.score)rounded_score = int(round(self.stats.score,-1))pstr = "{:,}".format(rounded_score)score_str = "Score: " + pstrself.score_image = self.font.render(score_str,True,self.text_color,self.ai_settings.bg_color)self.score_rect = self.score_image.get_rect()self.score_rect.right = self.screen_rect.right - 20self.score_rect.top = 10def 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.level_image,self.level_rect)self.ships.draw(self.screen)def prep_high_score(self):high_score = int(round(self.stats.high_score,-1))phstr = "{:,}".format(high_score)high_score_str = "Highest: " + phstrself.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.centerxself.high_score_rect.top = self.score_rect.topdef prep_level(self):self.level_image = self.font.render("Level: " + str(self.stats.level),True,self.text_color,self.ai_settings.bg_color)self.level_rect = self.level_image.get_rect()self.level_rect.right = self.score_rect.rightself.level_rect.top = self.score_rect.bottom + 10def 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.widthship.rect.y=10self.ships.add(ship)

游戏参数设定：settings.py

import pygame
class Settings():def __init__(self):self.screen_width = 960self.screen_height = 600self.bg_color = 200,255,200self.ship_limit = 3self.bullet_width = 3self.bullet_height = 15self.bullet_color = 255,100,100self.bullets_allowed = 5self.fleet_drop_speed = 10self.speedup_scale = 1.1self.score_scale = 1.5self.initialize_dynamic_settings()def initialize_dynamic_settings(self):self.ship_speed_factor = 5self.bullet_speed_factor = 8self.alien_speed_factor = 2self.fleet_direction = 1self.alien_points = 50def increase_speed(self):self.ship_speed_factor*=self.speedup_scaleself.bullet_speed_factor*=self.speedup_scaleself.alien_speed_factor*=self.speedup_scaleself.alien_points = int(self.alien_points * self.score_scale)

使用方法

将这些代码写入对应的.py文件中，放到同一个文件夹里，然后在该文件夹内创建一个名为image的文件夹，在里面放入ship.bmp和alien.bmp（必须是bmp文件）用来代替玩家飞船和外星人飞船，样式大小随意但不要太大（分辨率控制在50x50左右，太大了的话，emmm……你懂的；同时背景颜色要与窗口颜色一致）。游戏通过运行alien_invasion.py来启动，启动前别忘了检查是否安装了Python和Pygame的运行环境。如果你觉得游戏玩得不爽，可以在settings.py中可以调整窗口大小、颜色、子弹大小、游戏速度、难度增速、分数倍率等等，自定义游戏感觉，总有你喜欢的！