BaseMeshSync.cs

using System;
using System.Linq;
using System.Collections.Generic;
using System.Reflection;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.Animations;
using Unity.Collections;
using UnityEngine.Assertions;
using System.IO;
using System.Runtime.CompilerServices;
using JetBrains.Annotations;
using Unity.FilmInternalUtilities;
using UnityEngine.Rendering; //Volume, IndexFormat

#if AT_USE_SPLINES
using Unity.Mathematics;
#endif

#if AT_USE_HDRP
using UnityEngine.Rendering.HighDefinition;
using UnityEngine.Experimental.Rendering;
#endif

#if UNITY_EDITOR
using UnityEditor;
using UnityEditor.SceneManagement;
using Unity.FilmInternalUtilities.Editor;
#endif


[assembly: InternalsVisibleTo("Unity.Utilities.VariantExport")]

namespace Unity.MeshSync {
/// <summary>
/// A delegate to handle scene updates
/// </summary>
internal delegate void SceneHandler();

/// <summary>
/// A delegate to handle audio updates
/// </summary>
internal delegate void UpdateAudioHandler(AudioClip audio, AudioData data);

/// <summary>
/// A delegate to handle texture updates
/// </summary>
internal delegate void UpdateTextureHandler(Texture2D tex, TextureData data);

/// <summary>
/// A delegate to handle material updates
/// </summary>
internal delegate void UpdateMaterialHandler(Material mat, MaterialData data);

/// <summary>
/// A delegate to handle entity updates
/// </summary>
internal delegate void UpdateEntityHandler(GameObject obj, TransformData data);

/// <summary>
/// A delegate to handle animation updates
/// </summary>
internal delegate void UpdateAnimationHandler(AnimationClip anim, AnimationClipData data);

/// <summary>
/// A delegate to handle entity deletions
/// </summary>
internal delegate void DeleteEntityHandler(GameObject obj);

/// <summary>
/// A delegate to handle instance info updates
/// </summary>
/// <param name="data"></param>
internal delegate void UpdateInstanceInfoHandler(string path, GameObject go, Matrix4x4[] transforms);

/// <summary>
/// A delegate to handle instance meshes.
/// </summary>
internal delegate void UpdateInstancedEntityHandler(string path, GameObject go);

/// <summary>
/// A delegate to handle instance deletions
/// </summary>
internal delegate void DeleteInstanceHandler(string path);

/// <summary>
/// Internal analytics observer data
/// </summary>
public struct MeshSyncAnalyticsData {
    internal MeshSyncSessionStartAnalyticsData? sessionStartData;
    internal MeshSyncSyncAnalyticsData?         syncData;
}

/// <summary>
/// Data about sync.
/// </summary>
public struct MeshSyncSyncAnalyticsData {
    internal AssetType  assetType;
    internal EntityType entityType;
    internal string     syncMode;
}

/// <summary>
/// Information about the DCC tool used with MeshSync.
/// </summary>
public struct MeshSyncSessionStartAnalyticsData {
    public string DCCToolName;
}

//----------------------------------------------------------------------------------------------------------------------

/// <summary>
/// The base class of main MeshSync components (MeshSyncServer, SceneCachePlayer),
/// which encapsulates common functionalities
/// </summary>
[ExecuteInEditMode]
public abstract partial class BaseMeshSync : MonoBehaviour, IObservable<MeshSyncAnalyticsData>, ISerializationCallbackReceiver {
    #region EventHandler Declarations

    /// <summary>
    /// An event that is executed when the scene update is started
    /// </summary>
    internal event SceneHandler onSceneUpdateBegin;

    /// <summary>
    /// An event that is executed when an audio is updated
    /// </summary>
    internal event UpdateAudioHandler onUpdateAudio;

    /// <summary>
    /// An event that is executed when a texture is updated
    /// </summary>
    internal event UpdateTextureHandler onUpdateTexture;

    /// <summary>
    /// An event that is executed when an material is updated
    /// </summary>
    internal event UpdateMaterialHandler onUpdateMaterial;

    /// <summary>
    /// An event that is executed when an entity is updated
    /// </summary>
    internal event UpdateEntityHandler onUpdateEntity;

    /// <summary>
    /// An event that is executed when an animation is updated
    /// </summary>
    internal event UpdateAnimationHandler onUpdateAnimation;

    /// <summary>
    /// An event that is executed when an entity is deleted
    /// </summary>
    internal event DeleteEntityHandler onDeleteEntity;

    /// <summary>
    /// An event that is executed when the scene update is finished
    /// </summary>
    internal event SceneHandler onSceneUpdateEnd;

    internal event UpdateInstanceInfoHandler onUpdateInstanceInfo;

    internal event UpdateInstancedEntityHandler onUpdateInstancedEntity;

    internal event DeleteInstanceHandler onDeleteInstanceInfo;

    internal event DeleteInstanceHandler onDeleteInstancedEntity;

    #endregion EventHandler Declarations

    //----------------------------------------------------------------------------------------------------------------------

    internal void Init(string assetsFolder) {
        Assert.IsTrue(assetsFolder.StartsWith("Assets"));
        m_assetsFolder = assetsFolder.Replace('\\', '/');
        m_rootObject   = gameObject.transform;

        m_materialList.Clear();
        m_textureList.Clear();
        m_audioList.Clear();

        m_clientObjects.Clear();
        m_hostObjects.Clear();
        m_objIDTable.Clear();

        m_clientInstances.Clear();
        m_clientInstancedEntities.Clear();

        m_prefabDict.Clear();

        InitInternalV();
    }

    private protected abstract void InitInternalV();

    //----------------------------------------------------------------------------------------------------------------------

    #region Getter/Setter

    internal string GetAssetsFolder() {
        return m_assetsFolder;
    }

    public void SetAssetsFolder(string folder) {
        m_assetsFolder = folder;
    }

    internal Transform GetRootObject() {
        return m_rootObject;
    }

    internal void SetRootObject(Transform t) {
        m_rootObject = t;
    }


    internal IDictionary<string, EntityRecord> GetClientObjects() {
        return m_clientObjects;
    }

    #endregion Simple Getter/Setter

    #region Properties

    [SerializeField] private int currentSessionId = -1;

    private bool forceDeleteChildrenInNextSession = false;

    private protected string GetServerDocRootPath() {
        return Application.streamingAssetsPath + "/MeshSyncServerRoot";
    }

    private protected void SetSaveAssetsInScene(bool saveAssetsInScene) {
        m_saveAssetsInScene = saveAssetsInScene;
    }

    private protected void MarkMeshesDynamic(bool markMeshesDynamic) {
        m_markMeshesDynamic = markMeshesDynamic;
    }

    internal void EnableKeyValuesSerialization(bool kvEnabled) {
        m_keyValuesSerializationEnabled = kvEnabled;
    }

    internal abstract MeshSyncPlayerConfig GetConfigV();


    internal bool useCustomCameraMatrices {
        get { return m_useCustomCameraMatrices; }
        set { m_useCustomCameraMatrices = value; }
    }

    internal List<MaterialHolder> materialList {
        get { return m_materialList; }
    }

    internal List<TextureHolder> textureList {
        get { return m_textureList; }
    }

    internal PrefabDictionary prefabDict {
        get { return m_prefabDict; }
    }


#if UNITY_EDITOR

    protected void SetSortEntities(bool sortEntities) {
        m_sortEntities = sortEntities;
    }

    internal bool foldSyncSettings {
        get { return m_foldSyncSettings; }
        set { m_foldSyncSettings = value; }
    }

    internal bool foldImportSettings {
        get { return m_foldImportSettings; }
        set { m_foldImportSettings = value; }
    }

    internal bool foldMisc {
        get { return m_foldMisc; }
        set { m_foldMisc = value; }
    }

    internal bool foldMaterialList {
        get { return m_foldMaterialList; }
        set { m_foldMaterialList = value; }
    }

    internal bool foldAnimationTweak {
        get { return m_foldAnimationTweak; }
        set { m_foldAnimationTweak = value; }
    }

    internal bool foldExportAssets {
        get { return m_foldExportAssets; }
        set { m_foldExportAssets = value; }
    }
#endif

    #endregion

    //----------------------------------------------------------------------------------------------------------------------

    #region Impl

    private void SerializeDictionary<K, V>(Dictionary<K, V> dic, ref K[] keys, ref V[] values) {
        keys   = dic.Keys.ToArray();
        values = dic.Values.ToArray();
    }

    private void DeserializeDictionary<K, V>(Dictionary<K, V> dic, ref K[] keys, ref V[] values) {
        try {
            if (keys != null && values != null && keys.Length == values.Length) {
                int n = keys.Length;
                for (int i = 0; i < n; ++i)
                    dic[keys[i]] = values[i];
            }
        }
        catch (Exception e) {
            Debug.LogError(e);
        }

        keys   = null;
        values = null;
    }

    //----------------------------------------------------------------------------------------------------------------------

    /// <summary>
    /// Called during serialization as an implementation of ISerializationCallbackReceiver
    /// </summary>
    public void OnBeforeSerialize() {
        OnBeforeSerializeMeshSyncPlayerV();

#if UNITY_EDITOR
        SaveMaterialRenderTexturesToAssetDatabase();
#endif

        if (!m_keyValuesSerializationEnabled)
            return;

        SerializeDictionary(m_clientObjects, ref m_clientObjects_keys, ref m_clientObjects_values);
        SerializeDictionary(m_hostObjects, ref m_hostObjects_keys, ref m_hostObjects_values);
        SerializeDictionary(m_objIDTable, ref m_objIDTable_keys, ref m_objIDTable_values);

        m_baseMeshSyncVersion = CUR_BASE_MESHSYNC_VERSION;
    }


    /// <summary>
    /// Called during serialization as an implementation of ISerializationCallbackReceiver
    /// </summary>
    public void OnAfterDeserialize() {
        DeserializeDictionary(m_clientObjects, ref m_clientObjects_keys, ref m_clientObjects_values);
        DeserializeDictionary(m_hostObjects, ref m_hostObjects_keys, ref m_hostObjects_values);
        DeserializeDictionary(m_objIDTable, ref m_objIDTable_keys, ref m_objIDTable_values);

        OnAfterDeserializeMeshSyncPlayerV();

        if (CUR_BASE_MESHSYNC_VERSION == m_baseMeshSyncVersion)
            return;

        if (m_baseMeshSyncVersion < (int)BaseMeshSyncVersion.INITIAL_0_10_0) {
#pragma warning disable 612
            
            MeshSyncPlayerConfig config = GetConfigV();
            config?.UsePhysicalCameraParams(m_usePhysicalCameraParams);
#pragma warning restore 612
        }

        m_baseMeshSyncVersion = CUR_BASE_MESHSYNC_VERSION;
    }

    private protected abstract void OnBeforeSerializeMeshSyncPlayerV();
    private protected abstract void OnAfterDeserializeMeshSyncPlayerV();

    //----------------------------------------------------------------------------------------------------------------------

    #endregion

    #region Misc

    //[MethodImpl(MethodImplOptions.AggressiveInlining)]
    private protected bool Try(Action act) {
        try {
            act.Invoke();
            return true;
        }
        catch (Exception e) {
            if (GetConfigV().Logging)
                Debug.LogError(e);
            return false;
        }
    }

    //----------------------------------------------------------------------------------------------------------------------    
    private void MakeSureAssetDirectoryExists() {
#if UNITY_EDITOR
        if (Directory.Exists(m_assetsFolder))
            return;

        Directory.CreateDirectory(m_assetsFolder);
        AssetDatabase.Refresh();
#endif
    }

    //----------------------------------------------------------------------------------------------------------------------    

    private bool IsAsset(UnityEngine.Object obj) {
#if UNITY_EDITOR
        return AssetDatabase.Contains(obj);
#else
        return false;
#endif
    }

    private bool DestroyIfNotAsset(UnityEngine.Object obj) {
        if (obj != null && IsAsset(obj)) {
            DestroyImmediate(obj, false);
            return true;
        }

        return false;
    }

    internal string BuildPath(Transform t) {
        Transform parent = t.parent;
        if (parent != null && parent != m_rootObject)
            return BuildPath(parent) + "/" + t.name;
        else
            return "/" + t.name;
    }

    internal static Texture2D FindTexture(int id, List<TextureHolder> textureHolders) {
        if (id == Lib.invalidID)
            return null;
        TextureHolder rec = textureHolders.Find(a => a.id == id);
        return rec != null ? rec.texture : null;
    }

    internal Material FindMaterial(int id) {
        if (id == Lib.invalidID)
            return null;
        MaterialHolder rec = m_materialList.Find(a => a.id == id);
        return rec != null ? rec.material : null;
    }

    internal bool EraseMaterialRecord(int id) {
        return m_materialList.RemoveAll(v => v.id == id) != 0;
    }

    private protected int GetMaterialIndex(Material mat) {
        if (mat == null)
            return Lib.invalidID;

        for (int i = 0; i < m_materialList.Count; ++i)
            if (m_materialList[i].material == mat)
                return i;

        int            ret = m_materialList.Count;
        MaterialHolder tmp = new MaterialHolder();
        tmp.name     = mat.name;
        tmp.material = mat;
        tmp.id       = ret + 1;
        m_materialList.Add(tmp);
        return ret;
    }

    internal AudioClip FindAudio(int id) {
        if (id == Lib.invalidID)
            return null;
        AudioHolder rec = m_audioList.Find(a => a.id == id);
        return rec != null ? rec.audio : null;
    }

    internal int GetObjectlID(GameObject go) {
        if (go == null)
            return Lib.invalidID;

        if (m_objIDTable.TryGetValue(go, out int ret))
            return ret;

        ret              = ++m_objIDSeed;
        m_objIDTable[go] = ret;
        return ret;
    }

    //----------------------------------------------------------------------------------------------------------------------    


    private static Material CreateDefaultMaterial(string shaderName = null) {
        Material mat = new Material(GetShader(shaderName, out _));
        UpdateShader(mat, shaderName);
        return mat;
    }

    internal void ForceRepaint() {
#if UNITY_EDITOR
        if (!EditorApplication.isPlaying && !EditorApplication.isPaused) {
            SceneView.RepaintAll();
            UnityEditorInternal.InternalEditorUtility.RepaintAllViews();
        }
#endif
    }

    #endregion

    #region ReceiveScene

    internal void BeforeUpdateScene(FenceMessage? mes = null) {
        onSceneUpdateBegin?.Invoke();

        CheckForNewSession(mes);

        numberOfPropertiesReceived = 0;
    }

    public void ForceDeleteChildrenInNextSession() {
        forceDeleteChildrenInNextSession = true;
    }

    private void CheckForNewSession(FenceMessage? mes) {
#if UNITY_EDITOR
        if (!mes.HasValue || currentSessionId == mes.Value.SessionId) return;

        currentSessionId = mes.Value.SessionId;

        SendEventData(new MeshSyncAnalyticsData()
            { sessionStartData = new MeshSyncSessionStartAnalyticsData() { DCCToolName = mes.Value.DCCToolName } });

        if (transform.childCount <= 0) return;

        int choice;

        if (forceDeleteChildrenInNextSession) {
            choice                           = 2;
            forceDeleteChildrenInNextSession = false;
        }
        else {
            choice = EditorUtility.DisplayDialogComplex("A new session started.",
                "MeshSync detected that the DCC tool session has changed. To ensure that the sync state is correct you can delete previously synced objects, stash them and move them to another game object or ignore this and keep all children.",
                "Ignore and keep all children",
                "Stash",
                "Delete all children of the server");
        }

        switch (choice) {
            case 1:
                // Stash
                Transform stash = new GameObject($"{name}_stash").transform;
                for (int i = transform.childCount - 1; i >= 0; i--) {
                    Transform child = transform.GetChild(i);
                    child.SetParent(stash, true);
                }

                Init(GetAssetsFolder());
                break;
            case 2:
                // Destroy
                transform.DestroyChildrenImmediate();

                Init(GetAssetsFolder());
                break;
        }
#endif
    }

    private protected void UpdateScene(SceneData scene, bool updateNonMaterialAssets, bool logAnalytics = true) {
        MeshSyncPlayerConfig config = GetConfigV();
        // handle assets
        Try(() => {
            int numAssets = scene.numAssets;
            if (numAssets > 0) {
                bool save = false;
                for (int i = 0; i < numAssets; ++i) {
                    AssetData asset = scene.GetAsset(i);

                    //Only update non-MaterialAsset if specified
                    if (!updateNonMaterialAssets && asset.type != AssetType.Material)
                        continue;

                    switch (asset.type) {
                        case AssetType.File:
                            UpdateFileAsset((FileAssetData)asset);
                            break;
                        case AssetType.Audio:
                            UpdateAudioAsset((AudioData)asset);
                            break;
                        case AssetType.Texture:
                            UpdateTextureAsset((TextureData)asset);
                            break;
                        case AssetType.Material:
                            UpdateMaterialAssetV((MaterialData)asset);
                            break;
                        case AssetType.Animation:
                            UpdateAnimationAsset((AnimationClipData)asset, config);
                            save = true;
                            break;
                        default:
                            if (config.Logging)
                                Debug.Log("unknown asset: " + asset.name);
                            break;
                    }

                    if (logAnalytics) {
                        string syncMode = "None";
                        if (asset.type == AssetType.Material) {
                            syncMode = scene.GetMaterialSyncMode();

                            // TODO: Don't do this when GetMaterialSyncMode() works
                            if (textureList.Count > 0) syncMode = "Basic";
                        }

                        SendEventData(
                            new MeshSyncAnalyticsData() { syncData = new MeshSyncSyncAnalyticsData() { assetType = asset.type, syncMode = syncMode } });
                    }
                }
#if UNITY_EDITOR
                if (save)
                    AssetDatabase.SaveAssets();
#endif
            }
        });

        // handle entities
        Try(() => {
            int numObjects = scene.numEntities;
            for (int i = 0; i < numObjects; ++i) {
                EntityRecord  dst = null;
                TransformData src = scene.GetEntity(i);
                switch (src.entityType) {
                    case EntityType.Transform:
                        dst = UpdateTransformEntity(src, config);
                        break;
                    case EntityType.Camera:
                        dst = UpdateCameraEntity((CameraData)src, config);
                        break;
                    case EntityType.Light:
                        dst = UpdateLightEntity((LightData)src, config);
                        break;
                    case EntityType.Mesh:
                        dst = UpdateMeshEntity((MeshData)src, config);
                        break;
                    case EntityType.Points:
                        dst = UpdatePointsEntity((PointsData)src, config);
                        break;
                    case EntityType.Curve:
                        dst = UpdateCurveEntity((CurvesData)src, config);
                        break;
                    default:
                        Debug.LogError($"Unhandled entity type: {src.entityType}");
                        break;
                }

                SendEventData(new MeshSyncAnalyticsData() { syncData = new MeshSyncSyncAnalyticsData() { entityType = src.entityType } });


                if (dst != null && onUpdateEntity != null)
                    onUpdateEntity.Invoke(dst.go, src);
            }
        });

        // handle constraints
        Try(() => {
            int numConstraints = scene.numConstraints;
            for (int i = 0; i < numConstraints; ++i)
                UpdateConstraint(scene.GetConstraint(i));
        });

        // handle instance meshes
        Try(() => {
            int numMeshes = scene.numInstancedEntities;
            for (int i = 0; i < numMeshes; ++i) {
                TransformData src = scene.GetInstancedEntity(i);
                
                // If an instance entity is not part of the scene, it can only be supported if it is a Mesh
                //[TODO] Refactor code to support more types
                if (src.entityType != EntityType.Mesh)
                    continue;
                
                EntityRecord  dst = UpdateInstancedEntity(src);

                if (dst == null) return;

                if (onUpdateInstancedEntity != null)
                    onUpdateInstancedEntity(src.path, dst.go);
            }
        });

        // handle instances
        Try(() => {
            int numInstances = scene.numInstanceInfos;
            for (int i = 0; i < numInstances; ++i) {
                InstanceInfoData   src = scene.GetInstanceInfo(i);
                InstanceInfoRecord dst = UpdateInstanceInfo(src);
                if (onUpdateInstanceInfo != null)
                    onUpdateInstanceInfo.Invoke(src.path, dst.go, src.transforms);
            }
        });

        UpdateProperties(scene);

#if UNITY_EDITOR
        if (config.ProgressiveDisplay)
            ForceRepaint();
#endif

#if AT_USE_HDRP && UNITY_2021_2_OR_NEWER
        if (m_needToResetPathTracing) {
            HDRPUtility.ResetPathTracing();
            m_needToResetPathTracing = false;
        }
#endif
    }

    internal virtual void AfterUpdateScene() {
        // If none of the set messages had properties, we need to remove all properties:
        if (numberOfPropertiesReceived == 0) propertyInfos.Clear();

        List<string> deadKeys = null;

        // resolve bones
        foreach (KeyValuePair<string, EntityRecord> kvp in m_clientObjects) {
            EntityRecord rec = kvp.Value;
            if (rec.go == null) {
                if (deadKeys == null)
                    deadKeys = new List<string>();
                deadKeys.Add(kvp.Key);
                continue;
            }

            if (rec.smrUpdated) {
                rec.smrUpdated = false;

                SkinnedMeshRenderer smr = rec.skinnedMeshRenderer;
                if (rec.bonePaths != null && rec.bonePaths.Length > 0) {
                    int boneCount = rec.bonePaths.Length;

                    Transform[] bones = new Transform[boneCount];
                    for (int bi = 0; bi < boneCount; ++bi)
                        bones[bi] = FilmInternalUtilities.GameObjectUtility.FindByPath(m_rootObject, rec.bonePaths[bi]);

                    Transform root = null;
                    if (!string.IsNullOrEmpty(rec.rootBonePath))
                        root = FilmInternalUtilities.GameObjectUtility.FindByPath(m_rootObject, rec.rootBonePath);

                    if (root == null && boneCount > 0) {
                        // find root bone
                        root = bones[0];
                        for (;;) {
                            Transform parent = root.parent;
                            if (parent == null || parent == m_rootObject)
                                break;
                            root = parent;
                        }
                    }

                    smr.rootBone            = root;
                    smr.bones               = bones;
                    smr.updateWhenOffscreen = true; // todo: this should be turned off at some point

                    rec.bonePaths    = null;
                    rec.rootBonePath = null;
                }

                smr.enabled = rec.smrEnabled;
            }
        }

        if (deadKeys != null)
            foreach (string key in deadKeys)
                m_clientObjects.Remove(key);

        // resolve references
        // this must be another pass because resolving bones can affect references
        foreach (KeyValuePair<string, EntityRecord> kvp in m_clientObjects) {
            EntityRecord rec = kvp.Value;
            if (!string.IsNullOrEmpty(rec.reference)) {
                EntityRecord srcrec = null;
                if (m_clientObjects.TryGetValue(rec.reference, out srcrec) && srcrec.go != null) {
                    rec.materialIDs = srcrec.materialIDs;
                    UpdateReference(rec, srcrec, GetConfigV());
                }
            }
        }

        // reassign materials
        if (m_needReassignMaterials) {
            m_materialList = m_materialList.OrderBy(v => v.index).ToList();
            ReassignMaterials(false);
            m_needReassignMaterials = false;
        }

#if UNITY_EDITOR
        // sort objects by index
        if (m_sortEntities) {
            IOrderedEnumerable<EntityRecord> rec = m_clientObjects.Values.OrderBy(v => v.index);
            foreach (EntityRecord r in rec)
                if (r.go != null)
                    r.go.GetComponent<Transform>().SetSiblingIndex(r.index + 1000);
        }

        if (!EditorApplication.isPlaying || !EditorApplication.isPaused)
            // force recalculate skinning
            foreach (KeyValuePair<string, EntityRecord> kvp in m_clientObjects) {
                EntityRecord        rec = kvp.Value;
                SkinnedMeshRenderer smr = rec.skinnedMeshRenderer;
                if (smr != null && rec.smrEnabled && rec.go.activeInHierarchy) {
                    smr.enabled = false; // 
                    smr.enabled = true;  // force recalculate skinned mesh on editor. I couldn't find better way...
                }
            }

        if (!EditorApplication.isPlaying)
            // mark scene dirty
            EditorSceneManager.MarkSceneDirty(SceneManager.GetActiveScene());
#endif
        MeshSyncLogger.VerboseLog($"Scene updated.");

        if (onSceneUpdateEnd != null)
            onSceneUpdateEnd.Invoke();
    }

    //----------------------------------------------------------------------------------------------------------------------

    private void UpdateFileAsset(FileAssetData src) {
        MakeSureAssetDirectoryExists();
#if UNITY_EDITOR
        src.WriteToFile(m_assetsFolder + "/" + src.name);
#endif
    }

    private void UpdateAudioAsset(AudioData src) {
        MakeSureAssetDirectoryExists();
        AudioClip ac = null;

        AudioFormat format = src.format;
        if (format == AudioFormat.RawFile) {
#if UNITY_EDITOR
            // create file and import it
            string dstPath = m_assetsFolder + "/" + src.name;
            src.WriteToFile(dstPath);
            AssetDatabase.ImportAsset(dstPath);
            ac = AssetDatabase.LoadAssetAtPath<AudioClip>(dstPath);
            if (ac != null) {
                AudioImporter importer = (AudioImporter)AssetImporter.GetAtPath(dstPath);
                if (importer != null) {
                    // nothing todo for now
                }
            }
#endif
        }
        else {
#if UNITY_EDITOR
            // export as .wav and import it
            string dstPath = m_assetsFolder + "/" + src.name + ".wav";
            if (src.ExportAsWave(dstPath)) {
                AssetDatabase.ImportAsset(dstPath);
                ac = AssetDatabase.LoadAssetAtPath<AudioClip>(dstPath);
                if (ac != null) {
                    AudioImporter importer = (AudioImporter)AssetImporter.GetAtPath(dstPath);
                    if (importer != null) {
                        // nothing todo for now
                    }
                }
            }
#endif
            if (ac == null) {
                ac = AudioClip.Create(src.name, src.sampleLength, src.channels, src.frequency, false);
                ac.SetData(src.samples, 0);
            }
        }

        if (ac != null) {
            int         id  = src.id;
            AudioHolder dst = m_audioList.Find(a => a.id == id);
            if (dst == null) {
                dst    = new AudioHolder();
                dst.id = id;
                m_audioList.Add(dst);
            }

            dst.audio = ac;
            if (onUpdateAudio != null)
                onUpdateAudio.Invoke(ac, src);
        }
    }

    //----------------------------------------------------------------------------------------------------------------------

    private void UpdateTextureAsset(TextureData src) {
        MakeSureAssetDirectoryExists();
        Texture2D texture = null;
#if UNITY_EDITOR
        Action<string> doImport = (path) => {
            bool assetExisted = AssetDatabase.LoadAssetAtPath<Texture2D>(path) != null;

            AssetDatabase.ImportAsset(path);
            texture = AssetDatabase.LoadAssetAtPath<Texture2D>(path);
            if (texture != null) {
                TextureImporter importer = (TextureImporter)AssetImporter.GetAtPath(path);

                bool needReimport = false;

                // Make sure the full texture is used unless the user changed this setting before:
                if (!assetExisted) {
                    importer.npotScale = TextureImporterNPOTScale.None;
                    needReimport       = true;
                }

                if (importer != null)
                    switch (src.type) {
                        case TextureType.NormalMap:
                            importer.textureType = TextureImporterType.NormalMap;
                            needReimport         = true;
                            break;
                        case TextureType.NonColor:
                            importer.sRGBTexture = false;
                            needReimport         = true;
                            break;
                    }

                if (needReimport) {
                    importer.SaveAndReimport();
                    AssetDatabase.Refresh();
                }
            }
        };
#endif

        TextureFormat format = src.format;
        if (format == TextureFormat.RawFile) {
#if UNITY_EDITOR
            // write data to file and import
            string path = m_assetsFolder + "/" + src.name;
            if (src.WriteToFile(path))
                doImport(path);
#endif
        }
        else {
            texture      = new Texture2D(src.width, src.height, Misc.ToUnityTextureFormat(src.format), false);
            texture.name = src.name;
            texture.LoadRawTextureData(src.dataPtr, src.sizeInByte);
            texture.Apply();
#if UNITY_EDITOR
            // encode and write data to file and import
            // (script-generated texture works but can't set texture type such as normal map)
            bool   exported = false;
            string path     = null;
            switch (src.format) {
                case TextureFormat.Ru8:
                case TextureFormat.RGu8:
                case TextureFormat.RGBu8:
                case TextureFormat.RGBAu8: {
                    path     = m_assetsFolder + "/" + src.name + ".png";
                    exported = TextureData.WriteToFile(path, EncodeToPNG(texture));
                    break;
                }
                case TextureFormat.Rf16:
                case TextureFormat.RGf16:
                case TextureFormat.RGBf16:
                case TextureFormat.RGBAf16: {
                    path     = m_assetsFolder + "/" + src.name + ".exr";
                    exported = TextureData.WriteToFile(path, EncodeToEXR(texture, Texture2D.EXRFlags.CompressZIP));
                    break;
                }
                case TextureFormat.Rf32:
                case TextureFormat.RGf32:
                case TextureFormat.RGBf32:
                case TextureFormat.RGBAf32: {
                    path     = m_assetsFolder + "/" + src.name + ".exr";
                    exported = TextureData.WriteToFile(path, EncodeToEXR(texture, Texture2D.EXRFlags.OutputAsFloat | Texture2D.EXRFlags.CompressZIP));
                    break;
                }
            }

            if (exported) {
                texture = null;
                doImport(path);
            }
#endif
        }

        if (texture != null) {
            int           id  = src.id;
            TextureHolder dst = m_textureList.Find(a => a.id == id);
            if (dst == null) {
                dst    = new TextureHolder();
                dst.id = id;
                m_textureList.Add(dst);
            }

            dst.texture = texture;
            if (onUpdateTexture != null)
                onUpdateTexture.Invoke(texture, src);
        }
    }

    private byte[] EncodeToPNG(Texture2D tex) {
        return ImageConversion.EncodeToPNG(tex);
    }

    private byte[] EncodeToEXR(Texture2D tex, Texture2D.EXRFlags flags) {
        return ImageConversion.EncodeToEXR(tex, flags);
    }

    private protected abstract void UpdateMaterialAssetV(MaterialData materialData);

    private protected void UpdateMaterialAssetByDefault(MaterialData src, ModelImporterSettings importerSettings) {
        int    materialID   = src.id;
        string materialName = src.name;

        MaterialHolder dst = m_materialList.Find(a => a.id == materialID);

        //if (invalid && creating materials is allowed)
        if ((dst == null || dst.material == null || dst.name != materialName) && importerSettings.CreateMaterials) {
            if (null == dst) {
                dst = new MaterialHolder { id = materialID };
                m_materialList.Add(dst);
            }

            Assert.IsNotNull(dst);

#if UNITY_EDITOR
            dst.material = SearchMaterialInEditor(importerSettings.MaterialSearchMode, materialName);
            if (null != dst.material) {
                dst.ShouldApplyMaterialData = false;
            }
            else
#endif
            {
                dst.material      = CreateDefaultMaterial(src.shader);
                dst.material.name = materialName;
            }

            m_needReassignMaterials = true;
        }

        if (dst == null || dst.material == null)
            return;
        
        if (importerSettings.OverwriteExportedMaterials)
            dst.ShouldApplyMaterialData = true;

        dst.name  = materialName;
        dst.index = src.index;
        dst.color = src.color;

        Material destMat = dst.material;
        if (importerSettings.CreateMaterials && dst.ShouldApplyMaterialData) ApplyMaterialDataToMaterial(src, destMat, m_textureList);

        if (onUpdateMaterial != null)
            onUpdateMaterial.Invoke(destMat, src);
    }

    //----------------------------------------------------------------------------------------------------------------------    

#if UNITY_EDITOR

    [CanBeNull]
    private Material SearchMaterialInEditor(AssetSearchMode materialSearchMode, string materialName) {
        HashSet<string> materialPaths = null;
        string          assetsFolder  = GetAssetsFolder();
        switch (materialSearchMode) {
            case AssetSearchMode.LOCAL: {
                if (Directory.Exists(assetsFolder))
                    materialPaths = AssetEditorUtility.FindAssetPaths("t:Material ", materialName, new string[] { assetsFolder });
                break;
            }

            case AssetSearchMode.RECURSIVE_UP: {
                string nextFolder = assetsFolder;
                while (!string.IsNullOrEmpty(nextFolder) && (null == materialPaths || materialPaths.Count <= 0)) {
                    if (Directory.Exists(nextFolder))
                        materialPaths = AssetEditorUtility.FindAssetPaths("t:Material ", materialName, new string[] { nextFolder }, false);

                    nextFolder = PathUtility.GetDirectoryName(nextFolder, 1);
                }

                break;
            }
            case AssetSearchMode.EVERYWHERE: {
                materialPaths = AssetEditorUtility.FindAssetPaths("t:Material ", materialName);
                break;
            }
        }

        if (null == materialPaths || materialPaths.Count <= 0)
            return null;

        Material candidate = null;

        foreach (string materialPath in materialPaths) {
            Material material = AssetDatabase.LoadAssetAtPath<Material>(materialPath);
            candidate = material;
            //if there are multiple candidates, prefer the editable one (= not a part of fbx etc)
            if (((int)material.hideFlags & (int)HideFlags.NotEditable) == 0)
                return material;
        }

        Assert.IsNotNull(candidate);
        return candidate;
    }
#endif

    //----------------------------------------------------------------------------------------------------------------------    

    private void ApplyMaterialDataToMaterial(MaterialData src, Material destMat,
        List<TextureHolder> textureHolders) {
        int numKeywords = src.numKeywords;
        for (int ki = 0; ki < numKeywords; ++ki) {
            MaterialKeywordData kw = src.GetKeyword(ki);
            if (kw.value)
                destMat.EnableKeyword(kw.name);
            else
                destMat.DisableKeyword(kw.name);
        }

        UpdateShader(destMat, src.shader);

        // Put all properties in a list so we can look them up more easily:
        int                                   numProps           = src.numProperties;
        Dictionary<int, IMaterialPropertyData> materialProperties = new Dictionary<int, IMaterialPropertyData>(numProps);
        
        for (int pi = 0; pi < numProps; ++pi)
        {
            IMaterialPropertyData prop = src.GetProperty(pi);
            // Change parallax slider value to 0.005
            if (prop.nameID == MeshSyncConstants._Parallax)
            {
                CustomMaterialPropertyData parallax = new CustomMaterialPropertyData(prop);
                parallax.floatValue = 0.005f;
                materialProperties.Add(parallax.nameID, parallax);
            }
            else
            {
                materialProperties.Add(prop.nameID, prop);
            }
        }

        if (!materialProperties.ContainsKey(MeshSyncConstants._Glossiness)
            && !materialProperties.ContainsKey(MeshSyncConstants._GlossMapScale))
        {
            var id = MeshSyncConstants._Glossiness;
            if (!materialProperties.ContainsKey(MeshSyncConstants._MetallicGlossMap))
            {
                id = MeshSyncConstants._GlossMapScale;
                
                var textureChannel = new CustomMaterialPropertyData()
                {
                    intValue = 1,
                    arrayLength = 1,
                    type = IMaterialPropertyData.Type.Int,
                        nameID = MeshSyncConstants._SmoothnessTextureChannel
                };
                materialProperties.Add(textureChannel.nameID, textureChannel);
            }
            
            var glossiness = new CustomMaterialPropertyData
            {
                floatValue = 0.5f,
                arrayLength = 1,
                type = IMaterialPropertyData.Type.Float,
                nameID = id
            };
                
            materialProperties.Add(glossiness.nameID, glossiness);
        }
        
        // Change AO slider value to 0.25
        CustomMaterialPropertyData aoStrength = new CustomMaterialPropertyData
        {
            floatValue = 0.25f,
            arrayLength = 1,
            type = IMaterialPropertyData.Type.Float,
            nameID = MeshSyncConstants._OcclusionStrength
        };
        materialProperties.Add(aoStrength.nameID, aoStrength);

        foreach (KeyValuePair<int, IMaterialPropertyData> prop in materialProperties)
            ApplyMaterialProperty(destMat, textureHolders, prop.Value, prop.Key, materialProperties, src.shader);

        MapsBaker.BakeMaps(destMat, textureHolders, materialProperties);

        // Need to update shader again to ensure any custom setup is still there after the material properties were applied.
        UpdateCustomShaderSettings(destMat, src.shader);
    }

    private static bool HandleKeywords(Material destMat, List<TextureHolder> textureHolders,
        IMaterialPropertyData prop, string keyword) {
        // If the texture exists, enable its keyword, otherwise disable it:
        if (prop.type == IMaterialPropertyData.Type.Texture) {
            IMaterialPropertyData.TextureRecord rec = prop.textureValue;
            Texture2D                          tex = FindTexture(rec.id, textureHolders);

            if (tex != null) {
                destMat.EnableKeyword(keyword);
                return true;
            }
        }

        destMat.DisableKeyword(keyword);

        return false;
    }

    private static bool HandleKeywords(Material destMat, string keyword)
    {
        destMat.EnableKeyword(keyword);
        return true;
    }

    private static Dictionary<int, int[]> synonymMap = new Dictionary<int, int[]> {
        { MeshSyncConstants._Color, new[] { MeshSyncConstants._BaseColor } },
        { MeshSyncConstants._MainTex, new[] { MeshSyncConstants._BaseMap, MeshSyncConstants._BaseColorMap } },
        { MeshSyncConstants._Glossiness, new[] { MeshSyncConstants._Smoothness, MeshSyncConstants._GlossMapScale } },
        { MeshSyncConstants._BumpMap, new[] { MeshSyncConstants._NormalMap } },
        { MeshSyncConstants._EmissionMap, new[] { MeshSyncConstants._EmissiveColorMap } },
        { MeshSyncConstants._ParallaxMap, new[] { MeshSyncConstants._HeightMap } },
        { MeshSyncConstants._BumpScale, new[] { MeshSyncConstants._NormalScale } }
    };

    private void ApplyMaterialProperty(Material destMat,
        List<TextureHolder> textureHolders,
        IMaterialPropertyData prop,
        int propNameID,
        Dictionary<int, IMaterialPropertyData> materialProperties,
        string shaderName) {
        // Shaders use different names to refer to the same maps, this map contains those synonyms so we can apply them to every shader easily:
        if (synonymMap.TryGetValue(propNameID, out int[] synonyms))
            foreach (int synonym in synonyms)
                ApplyMaterialProperty(destMat, textureHolders, prop, synonym, materialProperties, shaderName);

        IMaterialPropertyData.Type propType = prop.type;
        if (!destMat.HasProperty(propNameID))
            return;

        // Enable alpha test if there is a color texture so alpha clipping works:
        if (propNameID == MeshSyncConstants._BaseMap ||
            propNameID == MeshSyncConstants._MainTex ||
            propNameID == MeshSyncConstants._BaseColorMap) {
            bool hasAlpha = HandleKeywords(destMat, textureHolders, prop, MeshSyncConstants._ALPHATEST_ON);
            if (hasAlpha) destMat.SetOverrideTag(MeshSyncConstants.RenderType, MeshSyncConstants.TransparentCutout);
#if AT_USE_HDRP
            destMat.SetFloat(MeshSyncConstants._AlphaCutoffEnable, hasAlpha ? 1 : 0);
            if (hasAlpha) {
                destMat.renderQueue = (int)RenderQueue.AlphaTest + 25;
                destMat.SetFloat(MeshSyncConstants._ZTestGBuffer, 3);
            }
#elif AT_USE_URP
            destMat.SetFloat(MeshSyncConstants._AlphaClip, hasAlpha ? 1 : 0);
#else
            if (hasAlpha) destMat.SetFloat(MeshSyncConstants._Mode, 1);
#endif
        }

        if (propNameID == MeshSyncConstants._EmissionColor) {
            if (destMat.globalIlluminationFlags == MaterialGlobalIlluminationFlags.EmissiveIsBlack) {
                destMat.globalIlluminationFlags = MaterialGlobalIlluminationFlags.RealtimeEmissive;

                HandleKeywords(destMat, textureHolders, prop, MeshSyncConstants._EMISSION);
            }
        }
        else if (propNameID == MeshSyncConstants._MetallicGlossMap) {
            HandleKeywords(destMat, textureHolders, prop, MeshSyncConstants._METALLICGLOSSMAP);
            HandleKeywords(destMat, textureHolders, prop, MeshSyncConstants._METALLICSPECGLOSSMAP);
        }
        else if (propNameID == MeshSyncConstants._BumpMap) {
            HandleKeywords(destMat, textureHolders, prop, MeshSyncConstants._NORMALMAP);
        }
        else if (propNameID == MeshSyncConstants._ParallaxMap) {
            HandleKeywords(destMat, textureHolders, prop, MeshSyncConstants._PARALLAXMAP);
        }
        else if (propNameID == MeshSyncConstants._OcclusionMap) {
            HandleKeywords(destMat, textureHolders, prop, MeshSyncConstants._OCCLUSIONMAP);
        }
        else if (propNameID == MeshSyncConstants._SmoothnessTextureChannel)
        {
            HandleKeywords(destMat, MeshSyncConstants._SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A);
        }
#if AT_USE_HDRP
        else if (propNameID == MeshSyncConstants._EmissiveColorMap) {
            Color baseEmissionColor = Color.white;

            if (materialProperties.TryGetValue(MeshSyncConstants._EmissionColor, out IMaterialPropertyData emissionColorProp))
                baseEmissionColor = emissionColorProp.vectorValue;

            float emissionStrength = 0;
            if (materialProperties.TryGetValue(MeshSyncConstants._EmissionStrength, out IMaterialPropertyData emissionStrengthProp))
                emissionStrength = emissionStrengthProp.floatValue;

            destMat.SetFloat(MeshSyncConstants._UseEmissiveIntensity, 1);
            destMat.SetFloat(MeshSyncConstants._EmissiveIntensityUnit, 0);
            destMat.SetFloat(MeshSyncConstants._EmissiveIntensity, emissionStrength);
            destMat.SetColor(MeshSyncConstants._EmissiveColorLDR, baseEmissionColor);
            destMat.SetColor(MeshSyncConstants._EmissiveColor, baseEmissionColor * emissionStrength);
        }
        else if (propNameID == MeshSyncConstants._HeightMap) {
            if (prop.type == IMaterialPropertyData.Type.Texture) {
                IMaterialPropertyData.TextureRecord rec = prop.textureValue;
                Texture2D                          tex = FindTexture(rec.id, textureHolders);
                if (tex != null) {
                    destMat.EnableKeyword(MeshSyncConstants._HEIGHTMAP);

                    // If there is no displacement mode set, set it to vertex displacement:
                    if (!destMat.IsKeywordEnabled(MeshSyncConstants._PIXEL_DISPLACEMENT)) {
                        destMat.EnableKeyword(MeshSyncConstants._VERTEX_DISPLACEMENT);
                        destMat.SetInt(MeshSyncConstants._DisplacementMode, 1);
                    }

                    // Fallback value in case the node setup in blender does not specify the height scale.
                    // Normally this is not used because the value comes from the displacement node:
                    float scale = 10;
                    if (materialProperties.TryGetValue(MeshSyncConstants._Parallax, out IMaterialPropertyData heightScaleProp))
                        scale = heightScaleProp.floatValue;

                    destMat.SetFloat(MeshSyncConstants._HeightMin, -scale);
                    destMat.SetFloat(MeshSyncConstants._HeightMax, scale);

                    // Amplitude is the difference between min height and max height: 
                    float amplitude = scale * 2;

                    // Convert from meters to centimeters:
                    destMat.SetFloat(MeshSyncConstants._HeightAmplitude, amplitude * 0.01f);
                }
            }
        }
        else if (propNameID == MeshSyncConstants._CoatMaskMap) {
            HandleKeywords(destMat, textureHolders, prop, MeshSyncConstants._MATERIAL_FEATURE_CLEAR_COAT);
        }
        else if (propNameID == MeshSyncConstants._CoatMask) {
            destMat.EnableKeyword(MeshSyncConstants._MATERIAL_FEATURE_CLEAR_COAT);
        }
#endif

        int len = prop.arrayLength;
        switch (propType) {
            case IMaterialPropertyData.Type.Int:
                destMat.SetInt(propNameID, prop.intValue);
                break;
            case IMaterialPropertyData.Type.Float:
                if (len == 1)
                    destMat.SetFloat(propNameID, prop.floatValue);
                else
                    destMat.SetFloatArray(propNameID, prop.floatArray);
                break;
            case IMaterialPropertyData.Type.Vector:
                if (len == 1)
                    destMat.SetVector(propNameID, prop.vectorValue);
                else
                    destMat.SetVectorArray(propNameID, prop.vectorArray);
                break;
            case IMaterialPropertyData.Type.Matrix:
                if (len == 1)
                    destMat.SetMatrix(propNameID, prop.matrixValue);
                else
                    destMat.SetMatrixArray(propNameID, prop.matrixArray);
                break;
            case IMaterialPropertyData.Type.Texture: {
                IMaterialPropertyData.TextureRecord rec = prop.textureValue;
                Texture2D                          tex = FindTexture(rec.id, textureHolders);
                // Allow setting of null textures to clear them:
                destMat.SetTextureAndReleaseExistingRenderTextures(propNameID, tex);
                if (rec.hasScaleOffset) {
                    destMat.SetTextureScale(propNameID, rec.scale);
                    destMat.SetTextureOffset(propNameID, rec.offset);
                }
            }
                break;
            case IMaterialPropertyData.Type.String:
                // Not used at the moment but would be: prop.stringValue;
                break;
            default: break;
        }
    }

    //----------------------------------------------------------------------------------------------------------------------

    private EntityRecord UpdateMeshEntity(MeshData data, MeshSyncPlayerConfig config) {
        if (!config.SyncMeshes)
            return null;

        TransformData dtrans = data.transform;
        MeshDataFlags dflags = data.dataFlags;
        EntityRecord  rec    = UpdateTransformEntity(dtrans, config);
        if (rec == null || dflags.unchanged)
            return null;

        if (!string.IsNullOrEmpty(rec.reference))
            // references will be resolved later in UpdateReference()
            return null;

        string     path              = dtrans.path;
        GameObject go                = rec.go;
        bool       activeInHierarchy = go.activeInHierarchy;
        if (!activeInHierarchy && !dflags.hasPoints)
            return null;

        return UpdateMeshEntity(data, config, rec);
    }

    private EntityRecord UpdateMeshEntity(MeshData data, MeshSyncPlayerConfig config, EntityRecord rec) {
        TransformData dtrans = data.transform;
        MeshDataFlags dflags = data.dataFlags;
        GameObject    go     = rec.go;
        Transform     trans  = go.transform;

        // allocate material list
        bool materialsUpdated = rec.BuildMaterialData(data);
        bool meshUpdated      = false;

        if (dflags.hasPoints && dflags.hasIndices) {
            // note:
            // assume there is always only 1 mesh split.
            // old versions supported multiple splits because vertex index was 16 bit (pre-Unity 2017.3),
            // but that code path was removed for simplicity and my sanity.
            if (data.numIndices == 0) {
                if (rec.mesh != null)
                    rec.mesh.Clear();
            }
            else {
                if (rec.mesh == null) {
                    rec.mesh      = new Mesh();
                    rec.mesh.name = trans.name;
                    if (m_markMeshesDynamic)
                        rec.mesh.MarkDynamic();
                    if (!m_saveAssetsInScene)
                        rec.mesh.hideFlags = HideFlags.DontSaveInEditor;
                    rec.mesh.indexFormat = IndexFormat.UInt32;
                }

                UpdateMeshEntity(ref rec.mesh, data);
            }

            meshUpdated = true;
        }
        else if (rec.mesh != null) {
            rec.mesh.Clear();
        }

        if (dflags.hasBones || dflags.hasBlendshapes) {
            SkinnedMeshRenderer smr = rec.skinnedMeshRenderer;
            if (smr == null) {
                materialsUpdated = true;
                smr              = rec.skinnedMeshRenderer = Misc.GetOrAddComponent<SkinnedMeshRenderer>(trans.gameObject);
                rec.DestroyMeshRendererAndFilter();
            }

            rec.smrUpdated = true;
            if (config.SyncVisibility && dtrans.dataFlags.hasVisibility)
                rec.smrEnabled = data.transform.visibility.visibleInRender;
            else
                rec.smrEnabled = smr.enabled;
            // disable temporarily to prevent error. restore on AfterUpdateScene()
            smr.enabled    = false;
            smr.sharedMesh = rec.mesh;

            // update bones
            if (dflags.hasBones) {
                if (dflags.hasRootBone)
                    rec.rootBonePath = data.rootBonePath;
                rec.bonePaths = data.bonePaths;
                // bones will be resolved in AfterUpdateScene()
            }
            else {
                smr.localBounds         = null != rec.mesh ? rec.mesh.bounds : new Bounds();
                smr.updateWhenOffscreen = false;
            }

            // update blendshape weights
            if (dflags.hasBlendshapes) {
                int meshBlendShapeCount = null != rec.mesh ? rec.mesh.blendShapeCount : 0;
                int numBlendShapes      = Math.Min(data.numBlendShapes, meshBlendShapeCount);
                for (int bi = 0; bi < numBlendShapes; ++bi) {
                    BlendShapeData bsd = data.GetBlendShapeData(bi);
                    smr.SetBlendShapeWeight(bi, bsd.weight);
                }
            }

#if AT_USE_HDRP
            UpdateRayTracingModeIfNecessary(smr);
#endif
        }
        else if (meshUpdated) {
            MeshFilter   mf = rec.meshFilter;
            MeshRenderer mr = rec.meshRenderer;

            if (mf == null) {
                materialsUpdated = true;

                mf = rec.meshFilter = Misc.GetOrAddComponent<MeshFilter>(trans.gameObject);

                mr = rec.meshRenderer = Misc.GetOrAddComponent<MeshRenderer>(trans.gameObject);
                if (rec.skinnedMeshRenderer != null) {
                    mr.sharedMaterials = rec.skinnedMeshRenderer.sharedMaterials;
                    DestroyImmediate(rec.skinnedMeshRenderer);
                    rec.skinnedMeshRenderer = null;
                }
            }

            if (config.SyncVisibility && dtrans.dataFlags.hasVisibility)
                mr.enabled = data.transform.visibility.visibleInRender;
            mf.sharedMesh  = rec.mesh;
            rec.smrEnabled = false;

#if AT_USE_HDRP
            UpdateRayTracingModeIfNecessary(mr);
#endif
        }

        if (meshUpdated) {
            MeshCollider collider = config.UpdateMeshColliders ? trans.GetComponent<MeshCollider>() : null;
            if (collider != null &&
                (collider.sharedMesh == null || collider.sharedMesh == rec.mesh))
                collider.sharedMesh = rec.mesh;
        }

        // assign materials if needed
        if (materialsUpdated)
            AssignMaterials(rec, false);

#if AT_USE_PROBUILDER
        if (UseProBuilder) {
            if (rec.mesh != null && (meshUpdated || materialsUpdated)) {
                //Debug.LogError("Rebuilding");
                ProBuilderBeforeRebuild?.Invoke();

                rec.proBuilderMeshFilter = Misc.GetOrAddComponent<UnityEngine.ProBuilder.ProBuilderMesh>(trans.gameObject);

                Material[] sharedMaterials                    = null;
                if (rec.meshRenderer != null) sharedMaterials = rec.meshRenderer.sharedMaterials;

                UnityEngine.ProBuilder.MeshOperations.MeshImporter importer = 
                    new UnityEngine.ProBuilder.MeshOperations.MeshImporter(rec.mesh, sharedMaterials, rec.proBuilderMeshFilter);
                // Disable quads, it is much slower:
                importer.Import(new UnityEngine.ProBuilder.MeshOperations.MeshImportSettings() { quads = false });

                // To refresh the internal probuilder mesh:
                rec.proBuilderMeshFilter.ToMesh();
                rec.proBuilderMeshFilter.Refresh();

                ProBuilderAfterRebuild?.Invoke();
            }
        }
        else {
            if (rec.proBuilderMeshFilter != null) {
                DestroyImmediate(rec.proBuilderMeshFilter);
                rec.proBuilderMeshFilter = null;
            }
        }
#endif
        return rec;
    }

#if AT_USE_PROBUILDER
    internal static Action ProBuilderBeforeRebuild;
    internal static Action ProBuilderAfterRebuild;
#endif

//--------------------------------------------------------------------------------------------------------------------------------------------------------------

#if AT_USE_HDRP
    private void UpdatePathTracingState() {
        m_pathTracingExists = false;
        if (!HDRPUtility.IsRayTracingActive())
            return;

        SceneComponents<Volume> sceneVolumes = SceneComponents<Volume>.GetInstance();
        sceneVolumes.Update();
        m_pathTracingExists = HDRPUtility.IsPathTracingActive(sceneVolumes.GetCachedComponents());
    }

    private void UpdateRayTracingModeIfNecessary(Renderer r) {
        if (!m_pathTracingExists)
            return;

        r.rayTracingMode         = UnityEngine.Experimental.Rendering.RayTracingMode.DynamicGeometry;
#if UNITY_2021_2_OR_NEWER
        m_needToResetPathTracing = true;
#endif
    }
#endif


//--------------------------------------------------------------------------------------------------------------------------------------------------------------

    private void UpdateMeshEntity(ref Mesh mesh, MeshData data) {
        bool keepIndices = false;
        if (mesh.vertexCount != 0) {
            if (data.dataFlags.topologyUnchanged) {
                keepIndices = true;
            }
            else {
                mesh.Clear();
                // Mesh.Clear() seems don't clear bindposes
                mesh.bindposes = null;
            }
        }

        int           numPoints = data.numPoints;
        MeshDataFlags dataFlags = data.dataFlags;
        if (dataFlags.hasPoints) {
            m_tmpV3.Resize(numPoints);
            data.ReadPoints(m_tmpV3);
            mesh.SetVertices(m_tmpV3.List);
        }

        if (dataFlags.hasNormals) {
            m_tmpV3.Resize(numPoints);
            data.ReadNormals(m_tmpV3);
            mesh.SetNormals(m_tmpV3.List);
        }

        if (dataFlags.hasTangents) {
            m_tmpV4.Resize(numPoints);
            data.ReadTangents(m_tmpV4);
            mesh.SetTangents(m_tmpV4.List);
        }

        for (int i = 0; i < CoreAPIConstants.MAX_UV; ++i)
            if (dataFlags.HasUV(i)) {
                m_tmpV2.Resize(numPoints);
                data.ReadUV(m_tmpV2, i);
                mesh.SetUVs(i, m_tmpV2.List);
            }

        if (dataFlags.hasColors) {
            m_tmpC.Resize(numPoints);
            data.ReadColors(m_tmpC);
            mesh.SetColors(m_tmpC.List);
        }

        if (dataFlags.hasBones) {
            mesh.bindposes = data.bindposes;

            {
                // bonesPerVertex + weights1
                NativeArray<byte>        bonesPerVertex = new NativeArray<byte>(numPoints, Allocator.Temp);
                NativeArray<BoneWeight1> weights1       = new NativeArray<BoneWeight1>(data.numBoneWeights, Allocator.Temp);
                data.ReadBoneCounts(Misc.ForceGetPointer(ref bonesPerVertex));
                data.ReadBoneWeightsV(Misc.ForceGetPointer(ref weights1));
                mesh.SetBoneWeights(bonesPerVertex, weights1);
                bonesPerVertex.Dispose();
                weights1.Dispose();
            }
        }

        if (dataFlags.hasIndices && !keepIndices) {
            int subMeshCount = data.numSubmeshes;
            mesh.subMeshCount = subMeshCount;
            for (int smi = 0; smi < subMeshCount; ++smi) {
                SubmeshData          submesh  = data.GetSubmesh(smi);
                SubmeshData.Topology topology = submesh.topology;

                m_tmpI.Resize(submesh.numIndices);
                submesh.ReadIndices(data, m_tmpI);

                if (topology == SubmeshData.Topology.Triangles) {
                    mesh.SetTriangles(m_tmpI.List, smi, false);
                }
                else {
                    MeshTopology mt = MeshTopology.Points;
                    switch (topology) {
                        case SubmeshData.Topology.Lines:
                            mt = MeshTopology.Lines;
                            break;
                        case SubmeshData.Topology.Quads:
                            mt = MeshTopology.Quads;
                            break;
                        default: break;
                    }

                    // note: tmpI.Array can't be used because its length is not current size but capacity.
                    mesh.SetIndices(m_tmpI.List.ToArray(), mt, smi, false);
                }
            }
        }

        if (dataFlags.hasBlendshapes) {
            PinnedList<Vector3> tmpBSP = new PinnedList<Vector3>(numPoints);
            PinnedList<Vector3> tmpBSN = new PinnedList<Vector3>(numPoints);
            PinnedList<Vector3> tmpBST = new PinnedList<Vector3>(numPoints);

            int numBlendShapes = data.numBlendShapes;
            for (int bi = 0; bi < numBlendShapes; ++bi) {
                BlendShapeData bsd       = data.GetBlendShapeData(bi);
                string         name      = bsd.name;
                float          numFrames = bsd.numFrames;
                for (int fi = 0; fi < numFrames; ++fi) {
                    bsd.ReadPoints(fi, tmpBSP);
                    bsd.ReadNormals(fi, tmpBSN);
                    bsd.ReadTangents(fi, tmpBST);
                    mesh.AddBlendShapeFrame(name, bsd.GetWeight(fi), tmpBSP.Array, tmpBSN.Array, tmpBST.Array);
                }
            }

            tmpBSP.Dispose();
            tmpBSN.Dispose();
            tmpBST.Dispose();
        }

        mesh.bounds = data.bounds;
        mesh.UploadMeshData(false);
    }

    //----------------------------------------------------------------------------------------------------------------------        
    private EntityRecord UpdatePointsEntity(PointsData data, MeshSyncPlayerConfig config) {
        TransformData   dtrans = data.transform;
        PointsDataFlags dflags = data.dataFlags;
        EntityRecord    rec    = UpdateTransformEntity(dtrans, config);
        if (rec == null || dflags.unchanged)
            return null;

        // reference (source mesh) will be resolved in UpdateReference()

        string     path = dtrans.path;
        GameObject go   = rec.go;

        PointCache dst = rec.pointCache;
        if (dst == null) {
            rec.pointCacheRenderer = Misc.GetOrAddComponent<PointCacheRenderer>(go);
            dst                    = rec.pointCache = Misc.GetOrAddComponent<PointCache>(go);
        }

        dst.Clear();

        int num = data.numPoints;
        dst.bounds = data.bounds;
        if (dflags.hasPoints) {
            dst.points = new Vector3[num];
            data.ReadPoints(dst.points);
        }

        if (dflags.hasRotations) {
            dst.rotations = new Quaternion[num];
            data.ReadRotations(dst.rotations);
        }

        if (dflags.hasScales) {
            dst.scales = new Vector3[num];
            data.ReadScales(dst.scales);
        }

        return rec;
    }

    static Transform FindOrCreateByPath(Transform parent, string path, Action<string> parentCreationCallback, bool worldPositionStays = true) {
        string[] names = path.Split('/');
        if (names.Length <= 0)
            return null;
        
        //if parent is null, search from root 
        Transform t             = parent;
        int       tokenStartIdx = 0;
        if (null == t) {
            string rootGameObjectName = names[0];
            t = FilmInternalUtilities.GameObjectUtility.FindFirstRoot(rootGameObjectName);
            if (null == t) {
                GameObject go = new GameObject(rootGameObjectName);
                t = go.GetComponent<Transform>();
            }

            tokenStartIdx = 1;
        }

        static Transform FindOrCreateChild(Transform t, string childName, out bool didCreate, bool worldPositionStays = true) {
            Transform childT = t.Find(childName);
            if (null != childT) {
                didCreate = false;
                return childT;
            }

            GameObject go = new GameObject(childName);
            childT = go.transform;
            childT.SetParent(t, worldPositionStays);
            didCreate = true;
            return childT;
        }
        
        //loop over hierarchy of names and generate parents that don't exist
        int          nameLength       = names.Length;
        List<string> processedParents = new List<string>();
        for (int i = tokenStartIdx; i < nameLength; ++i) {
            string nameToken = names[i];
            if (string.IsNullOrEmpty(nameToken))
                continue;
            
            processedParents.Add(nameToken);

            t = FindOrCreateChild(t, nameToken, out var didCreate, worldPositionStays);
            if (i < nameLength - 1 && didCreate) {
                var parentPath = String.Join("/", processedParents);
                if (!parentPath.StartsWith("/")) {
                    parentPath = $"/{parentPath}";
                }
                
                parentCreationCallback?.Invoke(parentPath);
            }

            if (null == t)
                return null;
        }

        return t;
    }

    void AddClientObject(string path, out EntityRecord rec) {
        if (m_clientObjects.TryGetValue(path, out rec))
            if (rec.go == null) {
                m_clientObjects.Remove(path);
                rec = null;
            }

        if (rec == null) {
            var trans = FindOrCreateByPath(m_rootObject, path,
                delegate(string parentPath) {
                    EntityRecord parentRec = null;
                    AddClientObject(parentPath, out parentRec);
                    if (parentRec.dataType == EntityType.Unknown)
                        parentRec.dataType = EntityType.Transform;
                },
                false);

            rec = new EntityRecord {
                go     = trans.gameObject,
                trans  = trans,
                recved = true
            };
            m_clientObjects.Add(path, rec);
        }
    }

    private EntityRecord UpdateTransformEntity(TransformData data, MeshSyncPlayerConfig config) {
        string path   = data.path;
        int    hostID = data.hostID;
        if (path.Length == 0)
            return null;

        EntityRecord rec   = null;
        if (hostID != Lib.invalidID) {
            if (m_hostObjects.TryGetValue(hostID, out rec))
                if (rec.go == null) {
                    m_hostObjects.Remove(hostID);
                    rec = null;
                }

            if (rec == null)
                return null;
        }
        else {
            AddClientObject(path, out rec);
        }

        return UpdateTransformEntity(data, config, rec);
    }

    private void SetVis(Behaviour c, VisibilityFlags visibility) {
        if (c != null) c.enabled = visibility.visibleInRender;
    }

    private void SetVis(Renderer c, VisibilityFlags visibility) {
        if (c != null) c.enabled = visibility.visibleInRender;
    }

    private EntityRecord UpdateTransformEntity(TransformData data, MeshSyncPlayerConfig config, EntityRecord rec) {
        Transform trans = rec.trans;
        if (trans == null)
            trans = rec.trans = rec.go.transform;

        TransformDataFlags dflags = data.dataFlags;
        if (!dflags.unchanged) {
            VisibilityFlags visibility = data.visibility;
            rec.index    = data.index;
            rec.dataType = data.entityType;

            // sync TRS
            if (config.SyncTransform) {
                if (dflags.hasPosition)
                    trans.localPosition = data.position;
                if (dflags.hasRotation)
                    trans.localRotation = data.rotation;
                if (dflags.hasScale)
                    trans.localScale = data.scale;
            }

            // visibility
            if (config.SyncVisibility && dflags.hasVisibility) {
                trans.gameObject.SetActive(visibility.active);

                if (!visibility.active) {
                    // If the parent is invisible because of layer visibility, make the
                    // child active inside the parent so enabling the parent also enables
                    // the child. This is important so instances work correctly.
                    string parentPath = data.path.Substring(0, data.path.LastIndexOf('/'));

                    if (m_clientObjects.TryGetValue(parentPath, out EntityRecord parentEntity))
                        if (parentEntity.hasVisibility &&
                            !parentEntity.visibility.active)
                            trans.gameObject.SetActive(visibility.visibleInRender);
                }

                SetVis(rec.meshRenderer, visibility);
                SetVis(rec.camera, visibility);
                SetVis(rec.skinnedMeshRenderer, visibility);
            }

            // visibility for reference
            rec.hasVisibility = dflags.hasVisibility;
            if (rec.hasVisibility)
                rec.visibility = visibility;

            // reference. will be resolved in AfterUpdateScene()
            if (dflags.hasReference)
                rec.reference = data.reference;
            else
                rec.reference = null;
        }

        return rec;
    }

    private EntityRecord UpdateCameraEntity(CameraData data, MeshSyncPlayerConfig config) {
        ComponentSyncSettings cameraSyncSettings = config.GetComponentSyncSettings(MeshSyncPlayerConfig.SYNC_CAMERA);
        if (!cameraSyncSettings.CanCreate)
            return null;

        TransformData   dtrans = data.transform;
        CameraDataFlags dflags = data.dataFlags;
        EntityRecord    rec    = UpdateTransformEntity(dtrans, config);
        if (rec == null || dflags.unchanged)
            return null;

        Camera cam = rec.camera;
        if (cam == null)
            cam = rec.camera = Misc.GetOrAddComponent<Camera>(rec.go);

        if (!cameraSyncSettings.CanUpdate)
            return null;

        if (config.SyncVisibility && dtrans.dataFlags.hasVisibility)
            cam.enabled = dtrans.visibility.visibleInRender;

        cam.orthographic = data.orthographic;
        if (cam.orthographic) {
            cam.orthographicSize = data.orthographic_size / cam.aspect / 2;
        }

        // use physical camera params if available
        if (config.IsPhysicalCameraParamsUsed() && dflags.hasFocalLength && dflags.hasSensorSize) {
            cam.usePhysicalProperties = true;
            cam.focalLength           = data.focalLength;
            cam.sensorSize            = data.sensorSize;
            cam.lensShift             = data.lensShift;
            //todo: gate fit support
        }
        else {
            if (dflags.hasFov && !cam.orthographic)
                cam.fieldOfView = data.fov;
        }

        if (dflags.hasNearPlane && dflags.hasFarPlane) {
            cam.nearClipPlane = data.nearPlane;
            cam.farClipPlane  = data.farPlane;
        }

        if (dflags.hasViewMatrix)
            cam.worldToCameraMatrix = data.viewMatrix;
        //else
        //    cam.ResetWorldToCameraMatrix();

        if (dflags.hasProjMatrix)
            cam.projectionMatrix = data.projMatrix;
        //else
        //    cam.ResetProjectionMatrix();
        return rec;
    }

    private EntityRecord UpdateLightEntity(LightData data, MeshSyncPlayerConfig config) {
        ComponentSyncSettings syncLightSettings = config.GetComponentSyncSettings(MeshSyncPlayerConfig.SYNC_LIGHTS);
        if (!syncLightSettings.CanCreate)
            return null;

        TransformData  dtrans = data.transform;
        LightDataFlags dflags = data.dataFlags;
        EntityRecord   rec    = UpdateTransformEntity(dtrans, config);
        if (rec == null || dflags.unchanged)
            return null;

        rec.SetLight(data, config.SyncVisibility, syncLightSettings.CanUpdate);
        return rec;
    }

    private void UpdateReference(EntityRecord dst, EntityRecord src, MeshSyncPlayerConfig config) {
        if (src.dataType == EntityType.Unknown) {
            Debug.LogError("MeshSync: should not be here!");
            return;
        }

        GameObject dstgo = dst.go;
        GameObject srcgo = src.go;
        if (src.dataType == EntityType.Camera) {
            Camera srccam = src.camera;
            if (srccam != null) {
                Camera dstcam = dst.camera;
                if (dstcam == null)
                    dstcam = dst.camera = Misc.GetOrAddComponent<Camera>(dstgo);
                if (config.SyncVisibility && dst.hasVisibility)
                    dstcam.enabled = dst.visibility.visibleInRender;
                dstcam.enabled       = srccam.enabled;
                dstcam.orthographic  = srccam.orthographic;
                dstcam.fieldOfView   = srccam.fieldOfView;
                dstcam.nearClipPlane = srccam.nearClipPlane;
                dstcam.farClipPlane  = srccam.farClipPlane;
            }
        }
        else if (src.dataType == EntityType.Light) {
            dst.SetLight(src, config.SyncVisibility);
        }
        else if (src.dataType == EntityType.Mesh) {
            Mesh                mesh   = src.mesh;
            MeshRenderer        srcmr  = src.meshRenderer;
            SkinnedMeshRenderer srcsmr = src.skinnedMeshRenderer;

            if (mesh != null) {
                PointCacheRenderer dstpcr = dst.pointCacheRenderer;
                if (dstpcr != null) {
                    if (config.SyncVisibility && dst.hasVisibility)
                        dstpcr.enabled = dst.visibility.visibleInRender;
                    dstpcr.sharedMesh = mesh;

                    if (dstpcr.sharedMaterials == null || dstpcr.sharedMaterials.Length == 0) {
                        Material[] materials = null;
                        if (srcmr != null)
                            materials = srcmr.sharedMaterials;
                        else if (srcsmr != null)
                            materials = srcsmr.sharedMaterials;

                        if (materials != null) {
                            foreach (Material m in materials)
                                m.enableInstancing = true;
                            dstpcr.sharedMaterials = materials;
                        }
                    }
                }
                else if (srcmr != null) {
                    MeshRenderer dstmr = dst.meshRenderer;
                    MeshFilter   dstmf = dst.meshFilter;
                    if (dstmr == null) {
                        dstmr = dst.meshRenderer = Misc.GetOrAddComponent<MeshRenderer>(dstgo);
                        dstmf = dst.meshFilter   = Misc.GetOrAddComponent<MeshFilter>(dstgo);
                    }

                    if (config.SyncVisibility && dst.hasVisibility)
                        dstmr.enabled = dst.visibility.visibleInRender;
                    dstmf.sharedMesh      = mesh;
                    dstmr.sharedMaterials = srcmr.sharedMaterials;
                }
                else if (srcsmr != null) {
                    SkinnedMeshRenderer dstsmr = dst.skinnedMeshRenderer;
                    if (dstsmr == null)
                        dstsmr = dst.skinnedMeshRenderer = Misc.GetOrAddComponent<SkinnedMeshRenderer>(dstgo);

                    // disable SkinnedMeshRenderer while updating
                    bool oldEnabled = dstsmr.enabled;
                    dstsmr.enabled             = false;
                    dstsmr.sharedMesh          = mesh;
                    dstsmr.sharedMaterials     = srcsmr.sharedMaterials;
                    dstsmr.bones               = srcsmr.bones;
                    dstsmr.rootBone            = srcsmr.rootBone;
                    dstsmr.updateWhenOffscreen = srcsmr.updateWhenOffscreen;
                    int blendShapeCount = mesh.blendShapeCount;
                    for (int bi = 0; bi < blendShapeCount; ++bi)
                        dstsmr.SetBlendShapeWeight(bi, srcsmr.GetBlendShapeWeight(bi));

                    if (config.SyncVisibility && dst.hasVisibility)
                        dstsmr.enabled = dst.visibility.visibleInRender;
                    else
                        dstsmr.enabled = oldEnabled;
                }

                // handle mesh collider
                if (config.UpdateMeshColliders) {
                    MeshCollider srcmc = srcgo.GetComponent<MeshCollider>();
                    if (srcmc != null && srcmc.sharedMesh == mesh) {
                        MeshCollider dstmc = Misc.GetOrAddComponent<MeshCollider>(dstgo);
                        dstmc.enabled        = srcmc.enabled;
                        dstmc.isTrigger      = srcmc.isTrigger;
                        dstmc.sharedMaterial = srcmc.sharedMaterial;
                        dstmc.sharedMesh     = mesh;
                        dstmc.convex         = srcmc.convex;
                        dstmc.cookingOptions = srcmc.cookingOptions;
                    }
                }
            }
        }
        else if (src.dataType == EntityType.Points) {
            PointCacheRenderer srcpcr = src.pointCacheRenderer;
            if (srcpcr != null) {
                PointCacheRenderer dstpcr = dst.pointCacheRenderer;
                dstpcr.sharedMesh = srcpcr.sharedMesh;

                Material[] materials = srcpcr.sharedMaterials;
                for (int i = 0; i < materials.Length; ++i)
                    materials[i].enableInstancing = true;
                dstpcr.sharedMaterials = materials;
            }
        }
    }

    private EntityRecord UpdateInstancedEntity(TransformData data) {
        MeshSyncPlayerConfig config = GetConfigV();

        if (!m_clientInstancedEntities.TryGetValue(data.path, out EntityRecord rec) || rec.go == null) {
            Transform trans =
                FilmInternalUtilities.GameObjectUtility.FindOrCreateByPath(m_rootObject, data.path, false);

            rec = new EntityRecord {
                go     = trans.gameObject,
                trans  = trans,
                recved = true
            };

            m_clientInstancedEntities[data.path] = rec;
        }

        UpdateTransformEntity(data, config, rec);
        UpdateMeshEntity((MeshData)data, config, rec);

        m_clientInstancedEntities[data.path] = rec;

        // If there is a instance info record that references the new object
        if (m_clientInstances.TryGetValue(data.path, out InstanceInfoRecord infoRecord)) {
            // Update the renderer reference
            infoRecord.go = rec.go;
            MeshSyncInstanceRenderer renderer = infoRecord.renderer;
            if (renderer != null) renderer.UpdateReference(rec.go);
        }

        return rec;
    }

    private HashSet<string> instanceNames = new HashSet<string>();

    private InstanceInfoRecord UpdateInstanceInfo(InstanceInfoData data) {
        string path = data.path;

        InstanceInfoRecord infoRecord;
        if (!m_clientInstances.TryGetValue(path, out infoRecord)) {
            infoRecord = new InstanceInfoRecord();
            m_clientInstances.Add(path, infoRecord);
        }

        EntityRecord instancedEntityRecord;
        // Look for reference in client instanced objects
        if (m_clientInstancedEntities.TryGetValue(path, out instancedEntityRecord))
            infoRecord.go = instancedEntityRecord.go;
        else if (m_clientObjects.TryGetValue(path, out instancedEntityRecord))
            infoRecord.go = instancedEntityRecord.go;
        else
            throw new Exception($"[MeshSync] No instanced entity found for path {data.path}");

        // Find parent for this instance:
        GameObject instanceRendererParent;
        if (m_clientObjects.TryGetValue(data.parentPath, out EntityRecord parentRecord)) {
            instanceRendererParent = parentRecord.go;
        }
        else {
            instanceRendererParent = m_rootObject.gameObject;

            Debug.LogWarningFormat(
                "[MeshSync] No entity found for parent path {0}, using root as parent", data.parentPath);
        }

        // Anything other than a mesh needs to use copies if we're in instance renderer mode:
        InstanceHandlingType instanceHandlingToUse = InstanceHandling;
        if (instanceHandlingToUse == InstanceHandlingType.InstanceRenderer &&
            instancedEntityRecord.dataType != EntityType.Mesh)
            instanceHandlingToUse = InstanceHandlingType.Copies;

        switch (instanceHandlingToUse) {
            case InstanceHandlingType.InstanceRenderer:
                UpdateInstanceInfo_InstanceRenderer(data, infoRecord, instanceRendererParent);
                break;
            case InstanceHandlingType.Copies:
            case InstanceHandlingType.Prefabs:
                UpdateInstanceInfo_CopiesAndPrefabs(data, infoRecord, instanceRendererParent);
                break;
            default:
                break;
        }

        return infoRecord;
    }
    
    private void UpdateInstanceInfo_CopiesAndPrefabs(
        InstanceInfoData data,
        InstanceInfoRecord infoRecord,
        GameObject instanceRendererParent) {
        // Make sure the other renderer is removed if this was not a copy or prefab before:
        if (infoRecord.renderer != null) {
            DestroyImmediate(infoRecord.renderer);
            infoRecord.renderer = null;
        }

        infoRecord.DeleteInstanceObjects();

        instanceNames.Add(infoRecord.go.name);
        
        if (infoRecord.go.transform.parent == null ||
            !instanceNames.Contains(infoRecord.go.transform.parent.name)) {
            GameObject instanceObjectOriginal;
            if (InstanceHandling == InstanceHandlingType.Prefabs)
                instanceObjectOriginal = GetOrCreatePrefab(data, infoRecord);
            else
                instanceObjectOriginal = infoRecord.go;

            if (instanceObjectOriginal == null) return;

            foreach (Matrix4x4 mat in data.transforms) {
                GameObject instancedCopy;
                if (InstanceHandling == InstanceHandlingType.Prefabs) {
#if UNITY_EDITOR
                    instancedCopy = (GameObject)PrefabUtility.InstantiatePrefab(instanceObjectOriginal,
                        instanceRendererParent.transform);
#else
                        instancedCopy = Instantiate(instanceObjectOriginal, instanceRendererParent.transform);
#endif
                }
                else {
                    instancedCopy = Instantiate(instanceObjectOriginal, instanceRendererParent.transform);
                }

                // Remove (Clone) at the end so the path lookup works:
                instancedCopy.name = instanceObjectOriginal.name;

                SetInstanceTransform(instancedCopy, instanceRendererParent, mat);
                EnableInstancedCopy(instancedCopy);

                infoRecord.instanceObjects.Add(instancedCopy);
            }
        }
        else {
            // This instance exists inside another instanced object,
            // update its transform to be correct relative to the parent on the infoRecord:
            // For example, in an object structure like this:
            // MainObject
            //   InstancedChildA
            //     InstancedChildB
            // For the instance renderer method, InstancedChildA and InstancedChildB exist as
            // MeshSyncInstanceRenderer components on MainObject and the transforms in data.transforms
            // are relative to MainObject. 
            // In this mode, where we use copies of the objects, InstancedChildB already exists as child of InstancedChildA
            // but the transform of InstancedChildB needs to be updated to be relative to MainObject.

            if (data.transforms.Length != 1) {
                Debug.LogWarning(
                    $"[MeshSync] There should never be more than 1 transform on instances inside other instances: {data.path}");
                return;
            }

            // Find the instanced copy as (a potentially indirect) child of `MainObject`:
            var instancedCopy =
                FilmInternalUtilities.GameObjectUtility.FindByPath(instanceRendererParent.transform, data.path);

            if (instancedCopy == null) {
                Debug.LogWarning(
                    $"[MeshSync] No instanced copy found for {data.path}");
                return;
            }

            // Set the transform relative to `MainObject`.
            // The easiest and safest way to do that is to:
            // - parent the instanced copy to `MainObject`
            // - set the transform matrix
            // - restore the original parent
            var originalParent = instancedCopy.parent;

            instancedCopy.transform.SetParent(instanceRendererParent.transform);

            SetInstanceTransform(instancedCopy.gameObject, instanceRendererParent, data.transforms[0]);

            instancedCopy.SetParent(originalParent);
        }
    }

    private void EnableInstancedCopy(GameObject obj) {
        obj.SetActive(true);

        MeshRenderer renderer = obj.GetComponent<MeshRenderer>();
        if (renderer != null)
            renderer.enabled = true;
    }

    private static void SetInstanceTransform(GameObject instancedCopy, GameObject parent, Matrix4x4 mat) {
        Transform objTransform = instancedCopy.transform;

        objTransform.localScale    = mat.lossyScale;
        objTransform.localPosition = mat.MultiplyPoint(Vector3.zero);

        // Calculate rotation here to avoid gimbal lock issue:
        Vector3 forward;
        forward.x = mat.m02;
        forward.y = mat.m12;
        forward.z = mat.m22;

        Vector3 upwards;
        upwards.x = mat.m01;
        upwards.y = mat.m11;
        upwards.z = mat.m21;

        objTransform.localRotation = Quaternion.LookRotation(forward, upwards);

#if DEBUG
        Matrix4x4 converted   = parent.transform.localToWorldMatrix * mat;
        Matrix4x4 localMatrix = objTransform.localToWorldMatrix;
        for (int x = 0; x < 3; x++)
        for (int y = 0; y < 3; y++)
            Debug.Assert(Math.Abs(localMatrix[x, y] - converted[x, y]) < 0.01f, "Matrices don't match!");
#endif
    }

    private GameObject GetOrCreatePrefab(InstanceInfoData data, InstanceInfoRecord infoRecord) {
        GameObject instanceObject = null;

        // Look for existing prefab and make sure the object exists:
        if (m_prefabDict.TryGetValue(data.path, out PrefabHolder existingPrefab)) {
            instanceObject = existingPrefab.prefab;
            if (instanceObject == null) m_prefabDict.Remove(data.path);
        }

        // Create it if it doesn't exist:
        if (instanceObject == null) {
#if UNITY_EDITOR // Cannot create prefabs when not in editor.
            ExportMeshes();
            ExportMaterials();

            string pathWithoutSlash = data.path.Trim('/');
            string prefabLocation   = Path.Combine(m_assetsFolder, Misc.SanitizeFileName(pathWithoutSlash) + ".prefab");

            bool wasActive = infoRecord.go.activeSelf;
            infoRecord.go.SetActive(true);

            GameObject prefab = PrefabUtility.SaveAsPrefabAssetAndConnect(infoRecord.go, prefabLocation,
                InteractionMode.AutomatedAction);

            AssetDatabase.SaveAssets();

            m_prefabDict[data.path] = new PrefabHolder { name = data.path, prefab = prefab };

            instanceObject = prefab;

            infoRecord.go.SetActive(wasActive);
#endif
        }

        return instanceObject;
    }

    private static void UpdateInstanceInfo_InstanceRenderer(InstanceInfoData data, InstanceInfoRecord infoRecord,
        GameObject instanceRendererParent) {
        infoRecord.DeleteInstanceObjects();

        if (instanceRendererParent != null && infoRecord.renderer == null)
            infoRecord.renderer = instanceRendererParent.AddComponent<MeshSyncInstanceRenderer>();

        infoRecord.renderer.UpdateAll(data.transforms, infoRecord.go);
    }

    private void UpdateConstraint(ConstraintData data) {
        Transform trans = FilmInternalUtilities.GameObjectUtility.FindOrCreateByPath(m_rootObject, data.path, false);
        if (trans == null)
            return;

        Action<IConstraint> basicSetup = (c) => {
            int ns = data.numSources;
            while (c.sourceCount < ns)
                c.AddSource(new ConstraintSource());
            for (int si = 0; si < ns; ++si) {
                ConstraintSource s = c.GetSource(si);
                s.sourceTransform = FilmInternalUtilities.GameObjectUtility.FindOrCreateByPath(m_rootObject, data.GetSourcePath(si), false);
            }
        };

        switch (data.type) {
            case ConstraintData.ConstraintType.Aim: {
                AimConstraint c = Misc.GetOrAddComponent<AimConstraint>(trans.gameObject);
                basicSetup(c);
                break;
            }
            case ConstraintData.ConstraintType.Parent: {
                ParentConstraint c = Misc.GetOrAddComponent<ParentConstraint>(trans.gameObject);
                basicSetup(c);
                break;
            }
            case ConstraintData.ConstraintType.Position: {
                PositionConstraint c = Misc.GetOrAddComponent<PositionConstraint>(trans.gameObject);
                basicSetup(c);
                break;
            }
            case ConstraintData.ConstraintType.Rotation: {
                RotationConstraint c = Misc.GetOrAddComponent<RotationConstraint>(trans.gameObject);
                basicSetup(c);
                break;
            }
            case ConstraintData.ConstraintType.Scale: {
                ScaleConstraint c = Misc.GetOrAddComponent<ScaleConstraint>(trans.gameObject);
                basicSetup(c);
                break;
            }
            default:
                break;
        }
    }

    //----------------------------------------------------------------------------------------------------------------------   

    private void UpdateAnimationAsset(AnimationClipData clipData, MeshSyncPlayerConfig config) {
        MakeSureAssetDirectoryExists();

#if UNITY_EDITOR

        clipData.Convert((InterpolationMode)config.AnimationInterpolation);
        if (config.KeyframeReduction)
            clipData.KeyframeReduction(config.ReductionThreshold, config.ReductionEraseFlatCurves);

        //float start = Time.realtimeSinceStartup;

        Dictionary<GameObject, AnimationClip> animClipCache = new Dictionary<GameObject, AnimationClip>();

        int numAnimations = clipData.numAnimations;
        for (int ai = 0; ai < numAnimations; ++ai) {
            AnimationData data = clipData.GetAnimation(ai);

            string       path = data.path;
            EntityRecord rec  = null;
            m_clientObjects.TryGetValue(path, out rec);

            Transform target = null;
            if (rec != null)
                target = rec.trans;
            if (target == null) {
                target = FilmInternalUtilities.GameObjectUtility.FindOrCreateByPath(m_rootObject, path, false);
                if (target == null)
                    return;
            }

            Transform root = target;
            while (root.parent != null && root.parent != m_rootObject)
                root = root.parent;

            Animator animator = Misc.GetOrAddComponent<Animator>(root.gameObject);

            // get or create animation clip
            AnimationClip clip = null;
            if (!animClipCache.TryGetValue(root.gameObject, out clip)) {
                if (animator.runtimeAnimatorController != null) {
                    AnimationClip[] clips = animator.runtimeAnimatorController.animationClips;
                    if (clips != null && clips.Length > 0) {
                        // note: this is extremely slow. animClipCache exists to cache the result and avoid frequent call.
                        AnimationClip tmp = animator.runtimeAnimatorController.animationClips[0];
                        if (tmp != null) {
                            clip                           = tmp;
                            animClipCache[root.gameObject] = tmp;
                        }
                    }
                }

                if (clip == null) {
                    clip = new AnimationClip();
                    string clipName = clipData.name;
                    if (clipName.Length > 0)
                        clipName = root.name + "_" + clipName;
                    else
                        clipName = root.name;

                    string dstPath = m_assetsFolder + "/" + Misc.SanitizeFileName(clipName) + ".anim";
                    clip = Misc.OverwriteOrCreateAsset(clip, dstPath);
                    animator.runtimeAnimatorController =
                        UnityEditor.Animations.AnimatorController.CreateAnimatorControllerAtPathWithClip(dstPath + ".controller", clip);
                    animClipCache[root.gameObject] = clip;
                }

                clip.frameRate = clipData.frameRate;
            }

            string animPath = path.Replace("/" + root.name, "");
            if (animPath.Length > 0 && animPath[0] == '/')
                animPath = animPath.Remove(0, 1);

            // get animation curves
            AnimationImportContext ctx = new AnimationImportContext() {
                clip                    = clip,
                root                    = root.gameObject,
                target                  = target.gameObject,
                path                    = animPath,
                enableVisibility        = config.SyncVisibility,
                usePhysicalCameraParams = config.IsPhysicalCameraParamsUsed()
            };
            if (rec != null) {
                if (rec.meshRenderer != null) ctx.mainComponentType             = typeof(MeshRenderer);
                else if (rec.skinnedMeshRenderer != null) ctx.mainComponentType = typeof(SkinnedMeshRenderer);
            }

            data.ExportToClip(ctx);
        }

        //Debug.Log("UpdateAnimationAsset() " + (Time.realtimeSinceStartup - start) + " sec");

        // fire event
        if (onUpdateAnimation != null)
            foreach (KeyValuePair<GameObject, AnimationClip> kvp in animClipCache)
                onUpdateAnimation.Invoke(kvp.Value, clipData);
#endif
    }

    private void ReassignMaterials(bool recordUndo) {
        foreach (KeyValuePair<string, EntityRecord> rec in m_clientObjects)
            AssignMaterials(rec.Value, recordUndo);
        foreach (KeyValuePair<int, EntityRecord> rec in m_hostObjects)
            AssignMaterials(rec.Value, recordUndo);
    }

    private void AssignMaterials(EntityRecord rec, bool recordUndo) {
        if (rec.go == null || rec.mesh == null || rec.materialIDs == null)
            return;

        Renderer r = rec.meshRenderer != null ? (Renderer)rec.meshRenderer : (Renderer)rec.skinnedMeshRenderer;
        if (r == null)
            return;

        bool       changed       = false;
        int        materialCount = rec.materialIDs.Length;
        Material[] materials     = new Material[materialCount];
        Material[] prevMaterials = r.sharedMaterials;
        Array.Copy(prevMaterials, materials, Math.Min(prevMaterials.Length, materials.Length));

        for (int si = 0; si < materialCount; ++si) {
            int      mid      = rec.materialIDs[si];
            Material material = FindMaterial(mid);
            if (material != null) {
                if (materials[si] == material)
                    continue;
                materials[si] = material;
                changed       = true;
            }
            else if (materials[si] == null) {
                materials[si] = FindDefaultMaterial();
                changed       = true;
            }
        }

        if (!changed)
            return;
#if UNITY_EDITOR
        if (recordUndo)
            Undo.RecordObject(r, "Assign Material");
#endif
        r.sharedMaterials = materials;
    }

    internal bool EraseInstanceRecord<R>(
        Identifier identifier,
        Dictionary<string, R> records,
        Action<R> onErase) {
        string path = identifier.name;

        bool ret = false;
        if (records.TryGetValue(path, out R rec)) {
            ret = records.Remove(path);

            onErase(rec);
        }

        return ret;
    }

    internal bool EraseInstanceInfoRecord(Identifier identifier) {
        return EraseInstanceRecord(identifier, m_clientInstances,
            delegate(InstanceInfoRecord record) {
                DestroyImmediate(record.renderer);

                record.DeleteInstanceObjects();

                if (onDeleteInstanceInfo != null)
                    onDeleteInstancedEntity(identifier.name);
            });
    }

    internal bool EraseInstancedEntityRecord(Identifier identifier) {
        return EraseInstanceRecord(identifier, m_clientInstancedEntities,
            delegate(EntityRecord record) {
                DestroyImmediate(record.go);
                if (onDeleteInstancedEntity != null)
                    onDeleteInstancedEntity(identifier.name);
            });
    }

    internal bool EraseEntityRecord(Identifier identifier) {
        int    id   = identifier.id;
        string path = identifier.name;

        GameObject   target = null;
        EntityRecord rec    = null;
        bool         ret    = false;
        if (id != 0 && m_hostObjects.TryGetValue(id, out rec)) {
            if (rec.go != null)
                target = rec.go;
            m_hostObjects.Remove(id);
        }
        else if (m_clientObjects.TryGetValue(path, out rec)) {
            if (rec.go != null)
                target = rec.go;
            ret = m_clientObjects.Remove(path);
        }

        if (target != null && !IsAsset(target)) {
            if (onDeleteEntity != null)
                onDeleteEntity.Invoke(target);
            DestroyImmediate(target);
        }

        return ret;
    }

    #endregion

    #region Tools

    private bool ApplyMaterialList(MaterialList ml) {
        if (ml == null)
            return false;

        List<MaterialHolder> mats = ml.materials;
        if (mats != null && mats.Count != 0) {
            bool updated       = false;
            int  materialCount = Mathf.Min(m_materialList.Count, ml.materials.Count);
            for (int mi = 0; mi < materialCount; ++mi) {
                MaterialHolder src = ml.materials[mi];
                if (src.material == null)
                    continue;
                MaterialHolder dst = m_materialList.Find(a => a.id == src.id);
                if (dst == null)
                    continue;
                dst.material = src.material;
                updated      = true;
            }

            if (updated)
                ReassignMaterials(false);
        }

        if (ml.nodes == null)
            return true;

        foreach (MaterialList.Node node in ml.nodes) {
            Transform trans = FilmInternalUtilities.GameObjectUtility.FindByPath(m_rootObject, node.path);
            if (trans == null)
                continue;

            Renderer r = trans.GetComponent<Renderer>();
            if (r != null)
                r.sharedMaterials = node.materials;
        }

        return true;
    }

    private Material FindDefaultMaterial() {
        if (m_cachedDefaultMaterial != null)
            return m_cachedDefaultMaterial;

        GameObject primitive = GameObject.CreatePrimitive(PrimitiveType.Plane);
        primitive.SetActive(false);
        m_cachedDefaultMaterial = primitive.GetComponent<MeshRenderer>().sharedMaterial;
        DestroyImmediate(primitive);
        return m_cachedDefaultMaterial;
    }

    //----------------------------------------------------------------------------------------------------------------------    
#if UNITY_EDITOR
    private void GenerateLightmapUV(GameObject go) {
        if (go == null)
            return;

        SkinnedMeshRenderer smr = go.GetComponent<SkinnedMeshRenderer>();
        if (smr != null) {
            Mesh mesh = smr.sharedMesh;
            if (mesh != null) {
                List<Vector2> uv = new List<Vector2>();
                mesh.GetUVs(0, uv);
                if (uv.Count == 0) {
                    Unwrapping.GenerateSecondaryUVSet(mesh);
                    Debug.Log("generated uv " + mesh.name);
                }
            }
        }
    }

    private void GenerateLightmapUV() {
        foreach (KeyValuePair<string, EntityRecord> kvp in m_clientObjects)
            GenerateLightmapUV(kvp.Value.go);
        foreach (KeyValuePair<int, EntityRecord> kvp in m_hostObjects)
            if (kvp.Value.mesh != null)
                GenerateLightmapUV(kvp.Value.go);
    }

    public void ExportMaterials(bool overwrite = true, bool useExistingOnes = false) {
        MakeSureAssetDirectoryExists();

        // need to avoid filename collision
        Misc.UniqueNameGenerator nameGenerator = new Misc.UniqueNameGenerator();
        string                   basePath      = m_assetsFolder;

        bool needSaveAssets = false;
        Func<Material, Material> doExport = (Material mat) => {
            if (mat == null || IsAsset(mat))
                return mat;

            string   dstPath  = string.Format("{0}/{1}.mat", basePath, nameGenerator.Gen(mat.name));
            Material existing = AssetDatabase.LoadAssetAtPath<Material>(dstPath);
            if (overwrite || existing == null) {
                mat = Misc.OverwriteOrCreateAsset(mat, dstPath);
                MeshSyncPlayerConfig config = GetConfigV();
                if (config.Logging)
                    Debug.Log("exported material " + dstPath);

                needSaveAssets = true;
            }
            else if (useExistingOnes && existing != null) {
                mat = existing;
            }

            return mat;
        };

        foreach (MaterialHolder m in m_materialList)
            m.material = doExport(m.material); // material maybe updated by SaveAsset()

        if (needSaveAssets)
            AssetDatabase.SaveAssets();
        ReassignMaterials(false);
    }

    private bool IsSubfolder(string parentPath, string childPath) {
        Uri           parentUri = new Uri(parentPath);
        DirectoryInfo childUri  = new DirectoryInfo(childPath).Parent;
        while (childUri != null) {
            if (new Uri(childUri.FullName) == parentUri) return true;
            childUri = childUri.Parent;
        }

        return false;
    }

    internal virtual void ClearInstancePrefabs() {
        MeshSyncLogger.VerboseLog("Clearing instance prefabs.");

        transform.DestroyChildrenImmediate();

        foreach (PrefabHolder prefabHolder in m_prefabDict.Values) {
            string path = AssetDatabase.GetAssetPath(prefabHolder.prefab);

            // Also delete its asset:
            string[] deps      = AssetDatabase.GetDependencies(path);
            string   assetName = Path.ChangeExtension(path, "asset");
            if (deps.Contains(assetName)) AssetDatabase.DeleteAsset(assetName);

            AssetDatabase.DeleteAsset(path);
        }

        m_prefabDict.Clear();
    }

    private void Export(KeyValuePair<string, EntityRecord> kvp, bool overwrite, bool useExistingOnes, string basePath, MeshSyncPlayerConfig config,
        Misc.UniqueNameGenerator nameGenerator) {
        Mesh mesh = kvp.Value.mesh;

        if (mesh == null)
            //if(kvp.Value.dataType == EntityType.Mesh)
            //{
            //    Debug.LogError($"Mesh was lost on {kvp.Key}");
            //}
            return;

        // If this is an asset but in another folder, still save it, if it changed:
        if (IsAsset(mesh)) {
            string currentPath  = Path.GetFullPath(GetAssetsFolder());
            string existingPath = Path.GetFullPath(AssetDatabase.GetAssetPath(mesh));
            if (IsSubfolder(currentPath, existingPath)) return;
        }

        string dstPath  = string.Format("{0}/{1}.asset", basePath, nameGenerator.Gen(mesh.name));
        Mesh   existing = AssetDatabase.LoadAssetAtPath<Mesh>(dstPath);
        if (overwrite || existing == null) {
            mesh           = Misc.OverwriteOrCreateAsset(mesh, dstPath);
            kvp.Value.mesh = mesh; // mesh maybe updated by SaveAsset()

            // Ensure the saved mesh is also linked on the meshfilter:
            if (kvp.Value.meshFilter != null) kvp.Value.meshFilter.sharedMesh                   = mesh;
            if (kvp.Value.skinnedMeshRenderer != null) kvp.Value.skinnedMeshRenderer.sharedMesh = mesh;

            if (config.Logging)
                Debug.Log("exported mesh " + dstPath);
        }
        else if (useExistingOnes && existing != null) {
            kvp.Value.mesh = existing;
        }
    }

    public void ExportMeshes(bool overwrite = true, bool useExistingOnes = false) {
        MakeSureAssetDirectoryExists();

        // need to avoid filename collision
        Misc.UniqueNameGenerator nameGenerator = new Misc.UniqueNameGenerator();
        string                   basePath      = GetAssetsFolder();

        // export client meshes
        MeshSyncPlayerConfig config = GetConfigV();

        foreach (KeyValuePair<string, EntityRecord> kvp in m_clientObjects) Export(kvp, overwrite, useExistingOnes, basePath, config, nameGenerator);

        foreach (KeyValuePair<string, EntityRecord> kvp in m_clientInstancedEntities) Export(kvp, overwrite, useExistingOnes, basePath, config, nameGenerator);

        // replace existing meshes
        int n = 0;
        foreach (KeyValuePair<int, EntityRecord> kvp in m_hostObjects) {
            EntityRecord rec = kvp.Value;
            if (rec.go == null || rec.mesh == null)
                continue;

            rec.origMesh.Clear(); // make editor can recognize mesh has modified by CopySerialized()
            EditorUtility.CopySerialized(rec.mesh, rec.origMesh);
            rec.mesh = null;

            MeshFilter mf = rec.go.GetComponent<MeshFilter>();
            if (mf != null)
                mf.sharedMesh = rec.origMesh;

            SkinnedMeshRenderer smr = rec.go.GetComponent<SkinnedMeshRenderer>();
            if (smr != null)
                smr.sharedMesh = rec.origMesh;

            if (config.Logging)
                Debug.Log("updated mesh " + rec.origMesh.name);
            ++n;
        }

        if (n > 0)
            AssetDatabase.SaveAssets();
    }

    internal bool ExportMaterialList(string path) {
        if (string.IsNullOrEmpty(path))
            return false;

        path = path.Replace(Application.dataPath, "Assets/");
        if (!path.EndsWith(".asset"))
            path = path + ".asset";

        MaterialList ml = ScriptableObject.CreateInstance<MaterialList>();
        // material list
        ml.materials = m_materialList;

        // extract per-node materials
        Action<Transform> exportNode = (n) => {
            foreach (Renderer r in n.GetComponentsInChildren<Renderer>())
                ml.nodes.Add(new MaterialList.Node {
                    path      = BuildPath(r.transform),
                    materials = r.sharedMaterials
                });
        };
        if (m_rootObject != null)
            exportNode(m_rootObject);
        else
            foreach (GameObject root in SceneManager.GetActiveScene().GetRootGameObjects())
                exportNode(root.transform);

        AssetDatabase.CreateAsset(ml, path);
        return true;
    }

    internal bool ImportMaterialList(string path) {
        if (string.IsNullOrEmpty(path))
            return false;

        path = path.Replace(Application.dataPath, "Assets/");

        MaterialList ml = AssetDatabase.LoadAssetAtPath<MaterialList>(path);
        return ApplyMaterialList(ml);
    }

    //Returns true if changed
    private bool IsMaterialAssignedInSceneView() {
        bool changed = false;
        foreach (KeyValuePair<string, EntityRecord> kvp in m_clientObjects) {
            EntityRecord rec = kvp.Value;
            if (rec.go != null && rec.go.activeInHierarchy) {
                Renderer mr = rec.go.GetComponent<Renderer>();
                if (mr == null || rec.mesh == null)
                    continue;

                Material[] materials = mr.sharedMaterials;
                int        n         = Math.Min(materials.Length, rec.materialIDs.Length);
                for (int si = 0; si < n; ++si) {
                    int            mid       = rec.materialIDs[si];
                    MaterialHolder matHolder = m_materialList.Find(a => a.id == mid);
                    if (matHolder == null || materials[si] == matHolder.material)
                        continue;
                    matHolder.material = materials[si];
                    changed            = true;
                    break;
                }
            }

            if (changed)
                break;
        }

        return changed;
    }


//---------------------------------------------------------------------------------------------------------------------    

    internal List<AnimationClip> GetAnimationClips() {
        List<AnimationClip> ret = new List<AnimationClip>();

        Action<GameObject> gatherClips = (go) => {
            AnimationClip[] clips = null;
            clips = AnimationUtility.GetAnimationClips(go);
            if (clips != null && clips.Length > 0)
                ret.AddRange(clips);
        };

        gatherClips(gameObject);
        // process children. root children should be enough.
        Transform trans      = transform;
        int       childCount = trans.childCount;
        for (int ci = 0; ci < childCount; ++ci)
            gatherClips(transform.GetChild(ci).gameObject);
        return ret;
    }

    private void OnSceneViewGUI(SceneView sceneView) {
        MeshSyncPlayerConfig config = GetConfigV();
        if (null == config) //may happen after deleting prefabs (SceneCache)
            return;

        if (!config.SyncMaterialList)
            return;

        if (Event.current.type != EventType.DragExited || Event.current.button != 0)
            return;

        bool changed = IsMaterialAssignedInSceneView();
        if (!changed)
            return;

        // assume last undo group is "Assign Material" performed by mouse drag & drop.
        // collapse reassigning materials into it.
        int group = Undo.GetCurrentGroup() - 1;
        ReassignMaterials(true);
        Undo.CollapseUndoOperations(@group);
        Undo.FlushUndoRecordObjects();
        ForceRepaint();
        m_onMaterialChangedInSceneViewCB?.Invoke();
    }

    internal void AssignMaterial(MaterialHolder holder, Material mat) {
        Undo.RegisterCompleteObjectUndo(this, "Assign Material");
        holder.material = mat;
        ReassignMaterials(true);
        Undo.FlushUndoRecordObjects();
        ForceRepaint();
    }

#endif //UNITY_EDITOR

    #endregion

//----------------------------------------------------------------------------------------------------------------------        

    #region Events

#if UNITY_EDITOR
    private void Reset() {
        // force disable batching for export
        MethodInfo method = typeof(PlayerSettings).GetMethod("SetBatchingForPlatform",
            BindingFlags.NonPublic | BindingFlags.Static);
        if (method == null)
            return;
        method.Invoke(null, new object[] { BuildTarget.StandaloneWindows, 0, 0 });
        method.Invoke(null, new object[] { BuildTarget.StandaloneWindows64, 0, 0 });
    }
#endif

    protected virtual void OnDestroy() {
        m_tmpI.Dispose();
        m_tmpV2.Dispose();
        m_tmpV3.Dispose();
        m_tmpV4.Dispose();
        m_tmpC.Dispose();
    }

//----------------------------------------------------------------------------------------------------------------------
    /// <summary>
    /// Monobehaviour's OnEnable(). Can be overridden
    /// </summary>
    private protected virtual void OnEnable() {
#if UNITY_EDITOR
        SceneView.duringSceneGui += OnSceneViewGUI;
#endif
    }

    /// <summary>
    /// Monobehaviour's OnDisable(). Can be overridden
    /// </summary>
    private protected virtual void OnDisable() {
#if UNITY_EDITOR
        SceneView.duringSceneGui -= OnSceneViewGUI;
#endif
    }

    private void Update() {
#if AT_USE_HDRP
        UpdatePathTracingState();
#endif
    }

    #endregion //Events

    internal int getNumObservers {
        get { return m_observers?.Count ?? 0; }
    }

    /// <summary>
    /// Send MeshSync sync event
    /// </summary>
    /// <param name="data">Asset type synced</param>
    private void SendEventData(MeshSyncAnalyticsData data) {
        foreach (IObserver<MeshSyncAnalyticsData> observer in m_observers) observer.OnNext(data);
    }

    /// <inheritdoc/>
    public IDisposable Subscribe(IObserver<MeshSyncAnalyticsData> observer) {
        m_observers.Add(observer);
        return null;
    }

    //----------------------------------------------------------------------------------------------------------------------

    // [TODO-sin: 2020-12-14] m_assetsFolder only makes sense for MeshSyncServer because we need to assign a folder that
    // will keep the synced resources as edits are performed on the DCC tool side.
    // For SceneCachePlayer, m_assetsFolder is needed only when loading the file, so it should be passed as a parameter

    [SerializeField] private string    m_assetsFolder = null; // Always starts with "Assets"
    [SerializeField] private Transform m_rootObject;

    [Obsolete] [SerializeField] private bool m_usePhysicalCameraParams = true;
    [SerializeField]            private bool m_useCustomCameraMatrices = true;

    [SerializeField] private protected List<MaterialHolder> m_materialList = new List<MaterialHolder>();
    [SerializeField] private           List<TextureHolder>  m_textureList  = new List<TextureHolder>();
    [SerializeField] private           List<AudioHolder>    m_audioList    = new List<AudioHolder>();
    [SerializeField] private           PrefabDictionary     m_prefabDict   = new PrefabDictionary();

    [SerializeField] private string[]       m_clientObjects_keys;
    [SerializeField] private EntityRecord[] m_clientObjects_values;
    [SerializeField] private int[]          m_hostObjects_keys;
    [SerializeField] private EntityRecord[] m_hostObjects_values;
    [SerializeField] private GameObject[]   m_objIDTable_keys;
    [SerializeField] private int[]          m_objIDTable_values;
    [SerializeField] private int            m_objIDSeed = 0;

#pragma warning disable 414
    [HideInInspector] [SerializeField] private int m_baseMeshSyncVersion = (int)BaseMeshSyncVersion.NO_VERSIONING;
#pragma warning restore 414
    private const int CUR_BASE_MESHSYNC_VERSION = (int)BaseMeshSyncVersion.INITIAL_0_10_0;

#if UNITY_EDITOR
    [SerializeField] private bool m_sortEntities       = true;
    [SerializeField] private bool m_foldSyncSettings   = true;
    [SerializeField] private bool m_foldImportSettings = true;
    [SerializeField] private bool m_foldMisc           = true;
    [SerializeField] private bool m_foldMaterialList   = true;
    [SerializeField] private bool m_foldAnimationTweak = true;
    [SerializeField] private bool m_foldExportAssets   = true;
#endif

    private bool m_saveAssetsInScene             = true;
    private bool m_markMeshesDynamic             = false;
    private bool m_needReassignMaterials         = false;
    private bool m_keyValuesSerializationEnabled = true;

    private List<IObserver<MeshSyncAnalyticsData>> m_observers = new List<IObserver<MeshSyncAnalyticsData>>();
    private Material                               m_cachedDefaultMaterial;

    private readonly           Dictionary<string, EntityRecord> m_clientObjects = new Dictionary<string, EntityRecord>();
    private protected readonly Dictionary<int, EntityRecord>    m_hostObjects   = new Dictionary<int, EntityRecord>();
    private readonly           Dictionary<GameObject, int>      m_objIDTable    = new Dictionary<GameObject, int>();

    [SerializeField] private protected InstanceInfoRecordDictionary m_clientInstances         = new InstanceInfoRecordDictionary();
    [SerializeField] private           EntityRecordDictionary       m_clientInstancedEntities = new EntityRecordDictionary();

    private protected Action m_onMaterialChangedInSceneViewCB = null;

#if AT_USE_HDRP
    private bool m_pathTracingExists      = false;
    
#if UNITY_2021_2_OR_NEWER
    private bool m_needToResetPathTracing = false;
#endif
#endif

//----------------------------------------------------------------------------------------------------------------------

    private PinnedList<int>     m_tmpI  = new PinnedList<int>();
    private PinnedList<Vector2> m_tmpV2 = new PinnedList<Vector2>();
    private PinnedList<Vector3> m_tmpV3 = new PinnedList<Vector3>();
    private PinnedList<Vector4> m_tmpV4 = new PinnedList<Vector4>();
    private PinnedList<Color>   m_tmpC  = new PinnedList<Color>();

#if AT_USE_SPLINES
    PinnedList<float3> m_tmpFloat3 = new PinnedList<float3>();
#endif

    //----------------------------------------------------------------------------------------------------------------------

    private enum BaseMeshSyncVersion {
        NO_VERSIONING  = 0, //Didn't have versioning in earlier versions
        INITIAL_0_10_0 = 1  //initial for version 0.10.0-preview 
    }
}
} //end namespace