Component-Entity-Systems

http://www.gamedev.net/page/resources/_/technical/game-programming/understanding-component-entity-systems-r3013

 

Normal OO:

 添加新的类有时候比较麻烦，已经定义好的类结构优势需要重构，可扩展性欠佳

 

Componet-entity-system里包括三个要素

•  Component
  • 可复用的组件，没有任何逻辑，只有数据
• Entity
• 是Component的集合，也没有逻辑，只有一堆Component
• Entity之间没有继承关系，它们通过加入不同的Component实现不同的功能
• System
  • 里面只有逻辑，控制Entity里的Component

一些例子：

Component

• Position (x, y)
• Velocity (x, y)
• Physics (body)
• Sprite (images, animations)
• Health (value)
• Character (name, level)
• Player (empty)

Entity

• Rock (Position, Sprite)
• Crate (Position, Sprite, Health)
• Sign (Position, Sprite, Text)
• Ball (Position, Velocity, Physics, Sprite)
• Enemy (Position, Velocity, Sprite, Character, Input, AI)
• Player (Position, Velocity, Sprite, Character, Input, Player)

System

• Movement (Position, Velocity) - Adds velocity to position
• Gravity (Velocity) - Accelerates velocity due to gravity
• Render (Position, Sprite) - Draws sprites
• PlayerControl (Input, Player) - Sets the player-controlled entity's input according to a controller
• BotControl (Input, AI) - Sets a bot-controlled entity's input according to an AI agent

 

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个人观点：这个component-entity-system有点太极端了，把逻辑内置到component以及entity里有点更符合OO的思想，就像UE3里那样