[游戏开发]unity标签判断拖动物体

给需要添加的物体添加标签，添加碰撞器 完事！

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

/// <summary>
/// 标签判断物体拖动
/// </summary>
public class drag : MonoBehaviour
{
    private Camera cam;
    private GameObject go;
    public static string btnName;
    private Vector3 screenSpace;
    private Vector3 offset;
    private bool isDrage = false;

    void Start()
    {
        cam = Camera.main;
    }
    void Update()
    {
        Ray ray = cam.ScreenPointToRay(Input.mousePosition);
        RaycastHit hitInfo;
        if (isDrage == false)
        {
            if (Physics.Raycast(ray, out hitInfo))
            {
                Debug.DrawLine(ray.origin, hitInfo.point);
                if (hitInfo.collider.tag=="drag")
                {
                    go = hitInfo.collider.gameObject;
                    //print(btnName);
                    screenSpace = cam.WorldToScreenPoint(go.transform.position);
                    offset = go.transform.position - cam.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenSpace.z));
                    btnName = go.name;
                }
               
            }
            else
            {
                btnName = null;
            }
        }
        if (Input.GetMouseButton(0))
        {
            Vector3 currentScreenSpace = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenSpace.z);
            Vector3 currentPosition = cam.ScreenToWorldPoint(currentScreenSpace) + offset;
            if (btnName != null)
            {
                go.transform.position = currentPosition;
            }

            isDrage = true;
        }
        else
        {
            isDrage = false;
        }
    }
}