using UnityEngine;

 using System.Collections;

 public class neccc : MonoBehaviour

 {

     public bool isMouseDown = false;

     private Vector3 lastMousePosition = Vector3.zero;

     Vector3 defaultPosition;

     public float speed = 0.5f;

     void Start()

     {

         lastMousePosition = Input.mousePosition;

     }

     // Update is called once per frame

     void Update()

     {

         /*

          * Camera.ScreenToWorldPoint 屏幕转世界位置

         从屏幕空间到世界空间的变化位置。

         屏幕空间以像素定义。屏幕的左下为(0,0)；右上是(pixelWidth,pixelHeight)，Z的位置是以世界单位衡量的到相机的距离。

         */

         #region 鼠标移动(手机屏幕移动)鼠标或者手指不一定要在角色上 角色跟着移动  注意：这里必须2D游戏。即。在创建游戏的时候选择2D

         if (Input.GetMouseButtonDown())

         {

             isMouseDown = true;

         }

         if (Input.GetMouseButtonUp())

         {

             isMouseDown = false;

             lastMousePosition = Vector3.zero;

         }

         if (isMouseDown)

         {

             if (lastMousePosition != Vector3.zero)

             {

                 //camera.main.ScreenToWorldPoint(Input.mousePosition);

                 Vector3 offetSet = Camera.main.ScreenToWorldPoint(Input.mousePosition) - lastMousePosition;

                 transform.position = transform.position + offetSet;

             }

             lastMousePosition = transform.position;

         }

         #endregion

     }

     /// <summary>

     /// 鼠标按下，记住当前鼠标的位置(如果是手机。则是触摸的位置)

     /// </summary>

     void OnMouseDown()

     {

         defaultPosition = Input.mousePosition;

     }

     /// <summary>

     /// 鼠标拖动(手机屏幕上拖动)移动物体

     /// </summary>

     void OnMouseDrag()

     {

         Vector3 v = Input.mousePosition - defaultPosition;

         transform.position = v;

         //平滑速度，根据需要用

         //transform.position += v * Time.deltaTime * speed;

         defaultPosition = Input.mousePosition;

     }

 }