using UnityEngine;
using System.Collections;//选择轴向
public enum directionEnum{x_dir,y_dir,z_dir,
}
public class DragObject : MonoBehaviour {// Use this for initializationpublic directionEnum myDirection;public Transform target;//需要拖拽的目标public bool isDrag;//表示当前是否可拖动public float MinDistance;public float MaxDistance;private Vector3 mousePos;/// </summary>void Start () {//下面是我用NGUI的事件添加的，也可以使用UGUI或者射线检测//UIEventListener.Get (this.gameObject).onDrag = DragTarget;//UIEventListener.Get (this.gameObject).onDragEnd = EndDrag;
}// Update is called once per framevoid Update () {}public void SetTarget(Transform go){this.target = go;mousePos = Input.mousePosition;//初始化鼠标初始位置,或者放到Start函数里
    }public void DragTarget(){if (isDrag) {Vector3 ScreenSpace = Camera.main.WorldToScreenPoint(target.position); //目标世界坐标转屏幕，获取z值Vector3 curScreenSpace = new Vector3(Input.mousePosition.x,Input.mousePosition.y,ScreenSpace.z);//当前鼠标位置转世界Vector3 offset = target.position - Camera.main.ScreenToWorldPoint (new Vector3 (mousePos.x, mousePos.y, ScreenSpace.z));//鼠标上一帧的世界位置和目标点的位置差Vector3 CurPosition = Camera.main.ScreenToWorldPoint(curScreenSpace)+offset;//鼠标当前位置+位置差switch (myDirection) {case directionEnum.x_dir:target.position = new Vector3 (Mathf.Clamp( CurPosition.x,MinDistance,MaxDistance), target.position.y, target.position.z); break;case directionEnum.y_dir:target.position = new Vector3 (target.position.x,Mathf.Clamp( CurPosition.y,MinDistance,MaxDistance), target.position.z); break;case directionEnum.z_dir:target.position = new Vector3 ( target.position.x, target.position.y, Mathf.Clamp( CurPosition.z,MinDistance,MaxDistance)); break;default:break;}mousePos = Input.mousePosition;}}}