January 2020
Intermediate to advanced
356 pages
6h 4m
Chinese
Content preview from Swift游戏开发经典实例
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10
｜
第
1
章
定时器
游戏状态在时钟走过一个固定的周期后就会更新。两次时钟周期之间进行的更
新，间隔时间可能很长（有一些运行在网页上的策略游戏甚至一天才更新一次），
也有可能很短（比如屏幕进行一次绘制就更新一次）。大部分实时游戏，比如
射击游戏和实时战略游戏，则采用非常短的更新周期。
外部输入
影响游戏状态改变的因素也有可能来自游戏外部。比如最常见的因素就是来自
网络传输的数据。类似的情况还包括来自内置传感器，如加速计产生的数据等。
而且，这种状态变更机制实质上仍然是一种特殊的定时器，因为不管网络还是
传感器都是以轮询的方式，每隔一段时间就去检查一下是否有新数据到达。
讨论
这些方法并不是互斥的。例如，你可以用一个定时器刷新游戏画面，但同时游戏状
态也会因用户的输入而改变。
逐帧刷新是效率最低的做法，但它对状态的修改也是最为频繁的，这种方式能使游
戏状态的改变更加平滑。
1.2
创建基于继承的设计
问题
有时候我们需要创建一种基于继承机制（如基于树形层次结构）的游戏框架，这种
框架的实现相对起来要简单一些。
解决方案
首先，定义一个类
GameObject
：
class GameObject {
func update(deltaTime : Float) {
游戏的设计
｜
11
// 'deltaTime'
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.