Unity Mesh合并

public class CombineTest : MonoBehaviour 
{
    public GameObject model;
    
    void Start() {
        Debug.Log(Time.realtimeSinceStartup);
        MeshFilter[] meshFilters = model.GetComponentsInChildren<MeshFilter>();
        Dictionary<string, List<CombineInstance>> combines = new Dictionary<string, List<CombineInstance>>();
        List<Material> mats = new List<Material>();
        List<CombineInstance> combineList = new List<CombineInstance>();

        for (int i = 0; i < meshFilters.Length; i++) {
            for (int j = 0; j < meshFilters[i].sharedMesh.subMeshCount; j++) {
                CombineInstance ci = new CombineInstance();
                MeshRenderer render = meshFilters[i].GetComponent<MeshRenderer>();
                Mesh m = Instantiate(meshFilters[i].sharedMesh);
                ci.mesh = m;
                ci.transform = meshFilters[i].transform.localToWorldMatrix;
                //ci.mesh.SetIndices(meshFilters[i].sharedMesh.GetIndices(j), meshFilters[i].sharedMesh.GetTopology(j), 0);
                ci.mesh.SetTriangles(meshFilters[i].sharedMesh.GetTriangles(j), 0);
                if (!combines.ContainsKey(render.materials[j].name)) {
                    combines.Add(render.materials[j].name, new List<CombineInstance>() { ci });
                    mats.Add(render.materials[j]);
                } else {
                    combines[render.materials[j].name].Add(ci);
                }
            }
        }
        Material[] matss = mats.ToArray();
        for (int i = 0;i < combines.Keys.Count; i++) {
            Mesh mesh01 = new Mesh();
            var com = combines[combines.Keys.ToArray()[i]].ToArray();
            mesh01.CombineMeshes(com, true);
            GameObject go1 = new GameObject();
            go1.AddComponent<MeshFilter>();
            go1.GetComponent<MeshFilter>().mesh = mesh01;
            go1.AddComponent<MeshRenderer>();
            go1.GetComponent<MeshRenderer>().material = matss[i];
            go1.SetActive(false);
            CombineInstance cccc = new CombineInstance();
            cccc.mesh = mesh01; 
            cccc.transform = go1.transform.localToWorldMatrix;
            combineList.Add(cccc);
            Destroy(go1);
        }
        Mesh mesh = new Mesh();
        var comL = combineList.ToArray();
        mesh.CombineMeshes(comL, false);
        GameObject go = new GameObject();
        go.AddComponent<MeshFilter>();
        go.GetComponent<MeshFilter>().mesh = mesh;
        go.AddComponent<MeshRenderer>();
        go.GetComponent<MeshRenderer>().materials = matss;
        Debug.Log(Time.realtimeSinceStartup);
    }
}