Python案例：飞船向右发射子弹

一、运行效果

二、实现步骤

1、创建Python项目ShipFireBullets

 

2、创建images目录，拷贝飞船图片ship.png

3、创建游戏设置文件settings.py

class Settings():
    # 初始化游戏设置
    def __init__(self):
        # 屏幕设置
        self.screen_width = 1000
        self.screen_height = 600
        self.bg_color = (230, 230, 230)

        # 飞船设置
        self.ship_speed_factor = 1.5

        # 子弹设置
        self.bullet_speed_factor = 1
        self.bullet_width = 15
        self.bullet_height = 1
        self.bullet_color = 60, 60, 60
        self.bullets_allowed = 3

4、创建飞船类文件ship.py

 

import pygame

class Ship():
    # 初始化飞船
    def __init__(self, ai_settings, screen):
        self.screen = screen
        self.ai_settings = ai_settings

        # 加载船图像，获取其矩形
        self.image = pygame.image.load('images/ship.bmp')
        self.rect = self.image.get_rect()
        self.screen_rect = screen.get_rect()

        # 移动标记
        self.moving_up = False
        self.moving_down = False

        # 每艘飞船出现在屏幕左边中央
        self.rect.left = 0
        self.rect.centery = self.screen_rect.centery

        # 设置飞船垂直中心位置的浮点值
        self.center = float(self.rect.centery)

    def update(self):
        # 向下移动，不能移出下边界
        if self.moving_down and self.rect.bottom < self.screen_rect.bottom:
            self.center += self.ai_settings.ship_speed_factor
        # 向上移动，不能移出上边界
        if self.moving_up and self.rect.top > 0:
            self.center -= self.ai_settings.ship_speed_factor

        # 设置飞船垂直中心位置的整数值
        self.rect.centery = self.center

    def blitme(self):
        # 在当前位置绘制飞船
        self.screen.blit(self.image, self.rect)

5、创建子弹类文件bullet.py

 

import pygame
from pygame.sprite import Sprite

# 子弹类
class Bullet(Sprite):
    # 初始化子弹
    def __init__(self, ai_settings, screen, ship):
        """在飞船当前位置创建一个子弹对象"""
        super().__init__()
        self.screen = screen

        # 在(0, 0)处创建子弹矩形，然后设置正确位置
        self.rect = pygame.Rect(0, 0, ai_settings.bullet_width, ai_settings.bullet_height)
        self.rect.centery = ship.rect.centery
        self.rect.right = ship.rect.right

        # 将子弹位置保存为十进制小数值
        self.x = float(self.rect.x)

        # 设置子弹颜色
        self.color = ai_settings.bullet_color
        # 设置子弹速度
        self.speed_factor = ai_settings.bullet_speed_factor

    # 更新子弹位置
    def update(self):
        # 更新子弹的十进制小数位置
        self.x += self.speed_factor
        # 更新子弹的矩形位置
        self.rect.x = self.x

    # 绘制子弹
    def draw_bullet(self):
        pygame.draw.rect(self.screen, self.color, self.rect)

6、创建函数文件game_functions.py

 

import sys

import pygame
from bullet import Bullet

# 检查按键按下事件
def check_keydown_events(event, ai_settings, screen, ship, bullets):
    if event.key == pygame.K_DOWN:
        ship.moving_down = True
    elif event.key == pygame.K_UP:
        ship.moving_up = True
    elif event.key == pygame.K_SPACE:
        fire_bullet(ai_settings, screen, ship, bullets)


# 发射子弹
def fire_bullet(ai_settings, screen, ship, bullets):
    # 子弹数未超过极限时，创建一个新子弹，添加到子弹组里
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)


# 检查按键弹起事件
def check_keyup_events(event, ship):
    if event.key == pygame.K_DOWN:
        ship.moving_down = False
    elif event.key == pygame.K_UP:
        ship.moving_up = False


# 检查按键与鼠标事件
def check_events(ai_settings, screen, ship, 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)


# 更新屏幕
def update_screen(ai_settings, screen, ship, bullets):
    # 设置屏幕背景色
    screen.fill(ai_settings.bg_color)
    # 飞船自我绘制
    ship.blitme()
    # 在飞船与外星人之后绘制全部子弹
    for bullet in bullets.sprites():
        bullet.draw_bullet()

    # 局部更新屏幕最近所绘
    pygame.display.flip()


# 更新子弹组
def update_bulletes(screen, bullets):
    # 更新子弹组
    bullets.update()
    # 删除已经消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.left > screen.get_rect().right:
            bullets.remove(bullet)
    # 打印子弹数量
    print(len(bullets), end=' ')

7、创建游戏主程序文件game_main.py

 

import pygame

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


def run_game():
    # 初始化游戏
    pygame.init()
    # 实例化游戏设置类
    ai_settings = Settings()
    # 创建屏幕
    screen = pygame.display.set_mode((ai_settings.screen_width, ai_settings.screen_height))
    # 设置屏幕标题
    pygame.display.set_caption("飞船发射子弹")

    # 创建一艘飞船
    ship = Ship(ai_settings, screen)
    # 创建一个组用于存放子弹
    bullets = Group()

    # 启动游戏主循环
    while True:
        # 监听事件
        gf.check_events(ai_settings, screen, ship, bullets)
        # 更新飞船
        ship.update()
        # 更新子弹组
        gf.update_bulletes(screen, bullets)
        # 更新屏幕
        gf.update_screen(ai_settings, screen, ship, bullets)


# 启动游戏
run_game()

运行game_main程序，结果如下：

 

 

按上下方向键可以让飞船上下移动，但是不能移出边界。按空格键，可以向右发射子弹。