unity3d：模型跟随鼠标运动，旋转

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

public class ModelMouseCtrl : MonoBehaviour {
    public Transform m_curShowObj;
    private Transform m_hitTrans;
    bool m_isLeftPress = false;
    bool m_isRightPress = false;
    public float m_xAngles = 0.0f;
    public float m_yAngles = 0.0f;

    private float m_xSpeed = 10.0f;
    private float m_ySpeed = 10.0f;
    
    // Update is called once per frame
    void Update () {
        if (Input.GetMouseButtonDown(0))
        {
            m_isLeftPress = true;
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            RaycastHit hit = new RaycastHit();//存储碰撞信息
            if (Physics.Raycast(ray,out hit))
            {
                m_hitTrans = hit.transform;
            }

        }

        if (Input.GetMouseButtonUp(0))
        {
            m_isLeftPress = false;
            m_hitTrans = null;
        }



        if (Input.GetMouseButton(1))
        {
            m_isRightPress = true;
            m_xAngles -= Input.GetAxis("Mouse X") * m_xSpeed ;
            m_yAngles += Input.GetAxis("Mouse Y") * m_ySpeed ;
        }

        if (Input.GetMouseButtonUp(1))
        {
            m_isRightPress = false;
        }
    }

    private void LateUpdate()
    {
        if (m_isLeftPress == true && m_hitTrans != null)
        {
            Vector3 screenPos = Camera.main.WorldToScreenPoint(m_hitTrans.position); 
            Vector3 mousePos = Input.mousePosition;
            mousePos.z = screenPos.z; 
            Vector3 worldPos = Camera.main.ScreenToWorldPoint(mousePos);
            m_hitTrans.position = worldPos;
        }

        if (m_isRightPress == true)
        {
            m_curShowObj.transform.localRotation = Quaternion.Euler(m_yAngles, 0, 0);
            m_curShowObj.transform.GetChild(0).localRotation = Quaternion.Euler(0, m_xAngles, 0) ;
        }
    }
}