Unity merge mesh and save

Put the scattered objects in the scene on the empty objects to ensure that the MeshFilter component is mounted.
The code is as follows

using UnityEditor;
using UnityEngine;


/// <summary>
/// 合并网格
/// </summary>
public class ChinarMergeMesh : MonoBehaviour
{
    
    
    void Start()
    {
    
    
        MergeMesh();
    }


    /// <summary>
    /// 合并网格
    /// </summary>
    private void MergeMesh()
    {
    
    
        MeshFilter[] meshFilters = GetComponentsInChildren<MeshFilter>();   //获取 所有子物体的网格
        CombineInstance[] combineInstances = new CombineInstance[meshFilters.Length]; //新建一个合并组，长度与 meshfilters一致
        for (int i = 0; i < meshFilters.Length; i++)                                  //遍历
        {
    
    
            combineInstances[i].mesh = meshFilters[i].sharedMesh;                   //将共享mesh，赋值
            combineInstances[i].transform = meshFilters[i].transform.localToWorldMatrix; //本地坐标转矩阵，赋值
        }
        Mesh newMesh = new Mesh();                                  //声明一个新网格对象
        newMesh.CombineMeshes(combineInstances);                    //将combineInstances数组传入函数
        gameObject.AddComponent<MeshFilter>().sharedMesh = newMesh; //给当前空物体，添加网格组件；将合并后的网格，给到自身网格
        AssetDatabase.CreateAsset(newMesh, "Assets/" + name + ".asset");
        //到这里，新模型的网格就已经生成了。运行模式下，可以点击物体的 MeshFilter 进行查看网格

        #region 以下是对新模型做的一些处理：添加材质，关闭所有子物体，添加自转脚本和控制相机的脚本

        //gameObject.AddComponent<MeshRenderer>().material = Resources.Load<Material>("Materials/Koala"); //给当前空物体添加渲染组件，给新模型网格上色;
        //foreach (Transform t in transform)                                                              //禁用掉所有子物体
        //{
    
    
        //    t.gameObject.SetActive(false);
        //}
        //gameObject.AddComponent<BallRotate>();
        //Camera.main.gameObject.AddComponent<ChinarCamera>().pivot = transform;

        #endregion
    }
}

Mount the code on an empty object to save it as a complete mesh