unity3d 鼠标事件

using UnityEngine;
using System.Collections;

public class mouse : MonoBehaviour {
    //private Vector3 lasePos;
    private Vector3 offSet;
    private Vector3 ScreenSpace;
    //1.
    void OnMouseDown()
    {
        ScreenSpace = Camera.main.WorldToScreenPoint(transform.position);
        offSet = transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, ScreenSpace.z));

        //lasePos = Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, ScreenSpace.z));
        print("down");
    }

    //2.
    void OnMouseUp()
    {
        print("up");
    }

    //3.
    void OnMouseDrag()
    {
        Vector3 curScreenSpace = new Vector3(Input.mousePosition.x, Input.mousePosition.y, ScreenSpace.z);
        Vector3 CurPosition = Camera.main.ScreenToWorldPoint(curScreenSpace) + offSet;
        transform.position = CurPosition;
        //Vector3 curPos = Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, ScreenSpace.z));
        //Vector3 gapPos = curPos - lasePos;
        //transform.position = transform.position + gapPos;
        //lasePos = curPos;

        print("drag");
    }

    //4.当鼠标移动到内部时
    void OnMouseEnter()
    {
        print("enter");
    }
    //5.当鼠标离开内部时
    void OnMouseExit()
    {
        print("exit");
    }
    //6.当鼠标持续停留在内部时
    void OnMouseOver()
    {
        print("over");
    }
    //7.鼠标停留在内部释放时调用
    void OnMouseUpAsButton()
    {
        print("upAsButton");
    }
}