在C＃/ XNA中使用通用函数进行碰撞检测 [英] Using Generic Functions for collision detection in C# / XNA

问题描述

Sphere
Cube
Plane

我在c＃/ XNA中制作物理引擎， p>

全部来源于

GameObject

I将所有对象存储在一个GameObjects列表中，我想遍历这个列表，并能够调用一个CheckCollision函数，该函数将为每对对象执行正确的函数。

例如

go是一个Sphere，

是一个球体

  if（CheckCollision（go，go2））
 {
 // do stuff 
} 
 
 bool CheckCollision（Sphere one，Sphere two）
 {
 //检查球体到球体
} 
 
 bool CheckCollision（球体，平面）
 {
 //检查领域飞机
} 
  

喜欢它只是去检查正确的功能，而不必使用检查。

谢谢。

解决方案

你可以使用虚拟调度：

 抽象类GameObject 
 {
抽象布尔CheckCollision（GameObject other）; 
抽象布尔CheckCollision（Sphere其他）; 
抽象布尔CheckCollision（Cube其他）; 
抽象布尔CheckCollision（平面其他）; 
} 
 
 class Sphere：GameObject 
 {
 override bool CheckCollision（GameObject other）{return other.CheckCollision（this）; } 
覆盖bool CheckCollision（Sphere other）{/ * ...实现... * /} 
覆盖bool CheckCollision（Cube other）{/ * ... implementation ... * /} 
覆盖bool CheckCollision（Plane other）{/ * ... implementation ... * /} 
} 
 
 class Cube：GameObject 
 {
 override bool CheckCollision（GameObject other）{return other.CheckCollision（this）; } 
覆盖bool CheckCollision（Sphere other）{/ * ...实现... * /} 
覆盖bool CheckCollision（Cube other）{/ * ... implementation ... * /} 
覆盖bool CheckCollision（Plane other）{/ * ...实现... * /} 
} 
 
类平面：GameObject 
 {
覆盖bool CheckCollision（GameObject other）{return other.CheckCollision（this）; } 
覆盖bool CheckCollision（Sphere other）{/ * ...实现... * /} 
覆盖bool CheckCollision（Cube other）{/ * ... implementation ... * /} 
覆盖bool CheckCollision（Plane other）{/ * ... implementation ... * /} 
} 
  

编辑

请考虑当发生这种情况时会发生什么情况：

  GameObject go1 = new Sphere（）; 
 GameObject go2 = new Cube（）; 
 bool collision = go1.CheckCollision（go2）; 
  

• 调用进入抽象的GameObject.CheckCollision（GameObject）方法
  
• 虚拟调度意味着我们去Sphere.CheckCollision（GameObject）Sphere.CheckCollision（GameObject）调用抽象的GameObject.CheckCollision （Sphere）方法。


• 虚拟调度意味着我们去Cube.CheckCollision（Sphere）！
  
  
  

  因此，如果语句是必要的，那么不需要检查。



  编辑2

  
  
  

  请参阅Eric Lippert在 https：// stackoverflow上的答案。 COM /一个/三十八万五千八百四十四分之二百三十六万七千九百八十一;第一种选择 - 访问者模式 - 基本上是上面概述的方法。 Eric在 https://stackoverflow.com/a/9069976/385844 上的其他答案也讨论了这个问题。

  
  

  I am making a physics engine in c# / XNA, I have three basic objects...

  Sphere Cube Plane

  that are all derived from

  GameObject

  I store all my objects in a list of GameObjects and I would like to loop through this list and be able to call a CheckCollision function that will go to the correct function for each pair of objects

  eg

  go is a Sphere,

  go2 is a Sphere

  if(CheckCollision(go, go2))
  {
    //do stuff
  }
  
  bool CheckCollision(Sphere one, Sphere two)
  {
    //Check Sphere to Sphere
  }
  
  bool CheckCollision(Sphere sphere, Plane plane)
  {
    //Check Sphere to Plane
  }
  

  and I would like it to just go to the correct function withour having to use if checks.

  Thank you.

  解决方案

  You could use virtual dispatch:

  abstract class GameObject
  {
      abstract bool CheckCollision (GameObject other);
      abstract bool CheckCollision (Sphere other);
      abstract bool CheckCollision (Cube other);
      abstract bool CheckCollision (Plane other);
  }
  
  class Sphere : GameObject
  {
      override bool CheckCollision (GameObject other) { return other.CheckCollision(this); }
      override bool CheckCollision (Sphere other) { /* ... implementation ... */ }
      override bool CheckCollision (Cube other) { /* ... implementation ... */ }
      override bool CheckCollision (Plane other) { /* ... implementation ... */ }
  }
  
  class Cube : GameObject
  {
      override bool CheckCollision (GameObject other) { return other.CheckCollision(this); }
      override bool CheckCollision (Sphere other) { /* ... implementation ... */ }
      override bool CheckCollision (Cube other) { /* ... implementation ... */ }
      override bool CheckCollision (Plane other) { /* ... implementation ... */ }
  }
  
  class Plane : GameObject
  {
      override bool CheckCollision (GameObject other) { return other.CheckCollision(this); }
      override bool CheckCollision (Sphere other) { /* ... implementation ... */ }
      override bool CheckCollision (Cube other) { /* ... implementation ... */ }
      override bool CheckCollision (Plane other) { /* ... implementation ... */ }
  }
  

  EDIT

  Consider what happens when you have this:

  GameObject go1 = new Sphere();
  GameObject go2 = new Cube();
  bool collision = go1.CheckCollision(go2);
  

  • The call goes to the abstract GameObject.CheckCollision(GameObject) method on the sphere.
  • Virtual dispatch means that we go to Sphere.CheckCollision(GameObject)
  • Sphere.CheckCollision(GameObject) calls the abstract GameObject.CheckCollision(Sphere) method on the cube.
  • Virtual dispatch means that we go to Cube.CheckCollision(Sphere)!

  Therefore, no type-checking if statements are necessary.

  EDIT 2

  See Eric Lippert's answer at https://stackoverflow.com/a/2367981/385844; the first option -- the visitor pattern -- is essentially the approach outlined above. Eric's other answer at https://stackoverflow.com/a/9069976/385844 also discusses this issue.

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