关于《python编程：从入到实践》第十二章的12-5课后习题答案

题目： 侧面射击 ： 编写一个游戏， 将一艘飞船放在屏幕左边， 并允许玩家上下移动飞船。 在玩家按空格键时， 让飞船发射一颗在屏幕中向右穿行的子弹， 并在子弹离开
屏幕而消失后将其删除。

在看这本书的时候也是半天没找到答案，于是自己写下答案，希望能给大家些帮助

答案：

主程序：side_fire.py

import pygame
from settings import Settings
import game_functions as gf
from ship import Ship
from pygame.sprite import Group


def run_game():
pygame.init()
sh_settings = Settings()
screen = pygame.display.set_mode((sh_settings.screen_width,sh_settings.screen_height))
ship = Ship(sh_settings,screen)
bullets = Group()
while True:
gf.check_events(sh_settings,screen,ship,bullets)
ship.update()
bullets.update()
gf.update_bullets(bullets,ship)
gf.update_screen(sh_settings,screen,ship,bullets)

run_game()

描述子弹信息的模块：bullet.py

import pygame
from pygame.sprite import Sprite


class Bullet(Sprite):
def __init__(self,sh_settings,screen,ship):
super(Bullet,self).__init__()
self.screen = screen

self.bullet_rect = pygame.Rect(0,0,sh_settings.bullet_width,sh_settings.bullet_height)
self.bullet_rect.centerx = ship.image_rect.left
self.bullet_rect.centery = ship.image_rect.centery


self.x = float(self.bullet_rect.centerx)


self.color = sh_settings.bullet_color
self.speed_factor = sh_settings.bullet_speed_factor


def update(self):
self.x += self.speed_factor


self.bullet_rect.x = self.x


def draw_bullet(self):

pygame.draw.rect(self.screen,self.color,self.bullet_rect)

实现游戏功能的模块：game_functions.py

import pygame
import sys
from bullets import Bullet


def check_events(sh_settings,screen,ship,bullets):
for event in pygame.event.get():
if event.type == pygame.QUIT:
sys.exit()
if event.type == pygame.KEYDOWN:
check_keydown_events(event,sh_settings,screen,ship,bullets)
if event.type == pygame.KEYUP:
check_keyup_events(event,ship)


def check_keydown_events(event,sh_settings,screen,ship,bullets):
if event.key == pygame.K_DOWN:
ship.moving_down = True
if event.key == pygame.K_UP:
ship.moving_up = True
if event.key == pygame.K_SPACE:
new_bullets(sh_settings,screen,ship,bullets)


def check_keyup_events(event,ship):
if event.key == pygame.K_DOWN:
ship.moving_down = False
if event.key == pygame.K_UP:
ship.moving_up = False


def update_bullets(bullets,ship):
bullets.update()
for bullet in bullets.copy():
if bullet.bullet_rect.right > ship.screen_rect.right:
bullets.remove(bullet)


def update_screen(sh_settings,screen,ship,bullets):
screen.fill(sh_settings.screen_color)
for bullet in bullets.sprites():
bullet.draw_bullet()
ship.blitme()
pygame.display.flip()


def new_bullets(sh_settings,screen,ship,bullets):
new_bullet = Bullet(sh_settings,screen,ship)

bullets.add(new_bullet)

存储游戏设置信息的模块：settings.py

class Settings(object):
def __init__(self):
self.screen_width = 1200
self.screen_height = 800
self.screen_color = (255,255,255)


self.bullet_width = 12
self.bullet_height = 4
self.bullet_color = (60,60,60)
self.bullet_speed_factor = 1

self.ship_speed_factor = 1

存储飞船信息的模块：ship.py

import pygame


class Ship(object):
def __init__(self,sh_settings,screen):
self.sh_settings = sh_settings
self.screen = screen


self.image = pygame.image.load('C:\Users\Administrator\Desktop\\test\\alient_invasion\images\ship.bmp')
self.image_rect = self.image.get_rect()
self.screen_rect = self.screen.get_rect()


self.image_rect.bottom = self.screen_rect.left
self.image_rect.centery = self.screen_rect.centery


self.center = float(self.image_rect.centery)


self.moving_down = False
self.moving_up = False


def update(self):
if self.moving_down and self.image_rect.bottom <= self.screen_rect.bottom:
self.center += self.sh_settings.ship_speed_factor
if self.moving_up and self.image_rect.top >= self.screen_rect.top:
self.center -= self.sh_settings.ship_speed_factor


self.image_rect.centery = self.center


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

使用python2.7.13 on win32,亲测完美运行。