Unity中结构体RaycaseResult详解

using System;  
namespace UnityEngine.EventSystems  
｛  
public struct RaycastResult  
｛  
//  
// Fields  
//  
public BaseRaycaster module; // BaseInputModule that raised the hit.  
public float distance; // Distance to the hit.  
public float index; // Hit index.  
public int depth; //The relative depth of the element.  
public int sortingLayer; // The SortingLayer of the hit object. 官方解释的这两个一样，完全不明白  
public int sortingOrder; // The SortingOrder for the hit object.  
public Vector3 worldPosition; // The world position of the where the raycast has hit.  
public Vector3 worldNormal; // The normal at the hit location of the raycast.  
public Vector2 screenPosition; // The screen position from which the raycast was generated.  
//  
// Properties  
//  
public GameObject gameObject ｛ // The GameObject that was hit by the raycast.  
get;  
set;  
｝  
public bool isValid ｛ // Is there an associated module and a hit GameObject.  
get;  
｝  
//  
// Methods  
//  
public void Clear ();  
public override string ToString ();  
｝  
｝