Unity3D拖动任意对象GameObject移动到任意地方

今天不是很忙，研究了一下拖拽GameObject移动到任意位置，沿x轴和z轴移动,其他的也就不说了，上代码：

using UnityEngine;
using System.Collections;

public class DragAndDrog : MonoBehaviour {

    private GameObject target;
    private bool isMouseDrag;
    private Vector3 screenPosition;
    private Vector3 offset;
	// Use this for initialization
	void Start () {

	}

	// Update is called once per frame
	void Update () {
        GameObjectDragAndDrog();

	}

    //任意拖拽

    private GameObject ReturnGameObjectDrag(out RaycastHit hit)
    {
        target = null;
        Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
        if (Physics.Raycast(ray.origin, ray.direction * 10, out hit))
        {
            target = hit.collider.gameObject;
        }
        return target;
    }

    //拖拽Updata
    private void GameObjectDragAndDrog()
    {
        if (Input.GetMouseButtonDown (0))
        {
            RaycastHit hitInfo;
            target = ReturnGameObjectDrag(out hitInfo);
            if (target != null)
            {
                isMouseDrag = true;
                screenPosition = Camera.main.WorldToScreenPoint(target.transform.position);
                offset = target.transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPosition.z));
            }      
        }

        if (Input.GetMouseButtonUp(0))
        {
            isMouseDrag = false;
        }

        if (isMouseDrag)
        {

            Vector3 currentScreenSpace = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPosition.z);
            Vector3 currentPosition = Camera.main.ScreenToWorldPoint(currentScreenSpace) + offset;
            target.transform.localPosition = new Vector3(currentPosition.x, currentPosition.y, currentPosition.z);

        }
    }

}

本脚本可以加载任意一个对象GameObject，场景中所有带Collider的对象，当鼠标点击拖动时候都可以沿x和z轴拖动。之前，都是要拖动那个GameObject就会写一个脚本挂在上面，今天实现了不用每一个要拖动的GameObject都挂载脚本，也不用将移动的GameObject赋给某个变量。