Unity中，让场景中的3D物件跟随鼠标移动

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

public class Test : MonoBehaviour
{
    [SerializeField]
    private Transform _trans;
    private void Update()
    {
        // 鼠标左键按下时，让_trans跟随鼠标移动
        if (Input.GetMouseButton(0))
        {
            var screenPos = Camera.main.WorldToScreenPoint(_trans.position);
            var mousePos = Input.mousePosition;
            mousePos.z = screenPos.z;
            var worldPos = Camera.main.ScreenToWorldPoint(mousePos);
            _trans.position = worldPos;
        }
    }
}