在本地保存 HoloLens2 上的持久世界锚

Question

我目前正在开展一个房间规模的 Unity 项目，我需要使用持久的世界锚在我的设备上本地保存 GameObjects 的位置，而无需使用任何 Internet 访问或 Wifi。

我正在使用Unity 2019.4.7 和HoloLens2 设备。

我从早期的HoloLens1 项目以及MRTK 2.4 的WorldAnchorManager-Class 中遇到了一些实现，这似乎与HoloToolkit 的旧WorldAnchorManager 非常相似。 （例如：https://forums.hololens.com/discussion/2667/how-to-use-unity-world-anchors，或https://codeholo.com/2019/02/01/anchoring-your-gameobjects-in-hololens-apps）

很遗憾，没有解决方案对我有用。

似乎WorldAnchors 甚至没有保存在WorldAnchorStore 中。我还尝试使用没有 WorldAnchorManager-Class 的官方 Unity WorldAnchorStore，即使它在 Unity 2020 中将被弃用。

有人可以提供一个应该在我的设置中工作的示例吗？

我也会很高兴看到每一个让锚点起作用的提示。

我当前使用WorldAnchorManager 的代码如下所示。 WorldAnchorManager-Instance 中的持久锚点已启用。

using Microsoft.MixedReality.Toolkit.Experimental.Utilities;
using UnityEngine;

public class SetWorldAnkeredObject : MonoBehaviour
{
    public GameObject anchoredObject;
    public WorldAnchorManager store;
    private string anchorId = "AnchoredCube";
    private bool savedRoot;

    void Start()
    {
        store.AttachAnchor(anchoredObject, anchorId);
    }

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.L))
        {
            store.AttachAnchor(anchoredObject, anchorId);
        }
        if (Input.GetKeyDown(KeyCode.Return))
        {
            if (anchoredObject != null)
                store.RemoveAnchor(anchorId);
            anchoredObject.transform.position = this.transform.position;
            store.AttachAnchor(anchoredObject, anchorId);
        }
    }
}

Answer 1

这里有几行代码取自我的一个项目，可能对你有所帮助。

导入

    private byte[] _importedData;
    private int _retryCount = 3;

    internal bool ImportAnchors()
    {
        _retryCount = 3;
        string path = GetWorldAnchorsDataPath(); // your path
        if (!File.Exists(path))
        {
            Debug.Log("Fail ImportWorldAnchors ImportAnchors File does not exist");
            return false;
        }

        _importedData = File.ReadAllBytes(path);
        Debug.Log("_importedData count " + _importedData.Length);
        WorldAnchorTransferBatch.ImportAsync(_importedData, OnImportComplete);
    }

    private void OnImportComplete(SerializationCompletionReason completionReason, WorldAnchorTransferBatch deserializedTransferBatch)
    {
        if (completionReason != SerializationCompletionReason.Succeeded)
        {
            Debug.Log("(" + _retryCount + ") Failed to import: " + completionReason.ToString());
            if (_retryCount > 0)
            {
                _retryCount--;
                WorldAnchorTransferBatch.ImportAsync(_importedData, OnImportComplete);
            }
            return;
        }
        Debug.Log("Success ImportWorldAnchors OnImportComplete, anchors count : " + deserializedTransferBatch.anchorCount);
        AnchorsManager.GetAndUpdateAnchorsFromBatch(deserializedTransferBatch);

        deserializedTransferBatch.Dispose();
    }    

  internal static string GetWorldAnchorsDataPath()
    {
        return Application.persistentDataPath + "/worldAnchors.dat";
    }
  

出口

 internal void ExportAnchors()
    {            
        string path = GetWorldAnchorsDataPath();
        if (File.Exists(path))
        {
            FileStream fileStream = File.Open(path, FileMode.Open);

            /* 
             * Set the length of filestream to 0 and flush it to the physical file.
             *
             * Flushing the stream is important because this ensures that
             * the changes to the stream trickle down to the physical file.
             * 
             */
            fileStream.SetLength(0);
            fileStream.Close(); // This flushes the content, too.
        }

        WorldAnchorTransferBatch transferBatch = new WorldAnchorTransferBatch();

        AddAnchorsToBatch(transferBatch); // your own function to use your batch
        Debug.Log("Nb anchors in batch : " + transferBatch.anchorCount);
        WorldAnchorTransferBatch.ExportAsync(transferBatch, OnExportDataAvailable, OnExportComplete);
    }

    private void OnExportDataAvailable(byte[] data)
    {
        AppendAllBytes(GetWorldAnchorsDataPath(), data);    
    }

    private void OnExportComplete(SerializationCompletionReason completionReason)
    {
        if (completionReason != SerializationCompletionReason.Succeeded)
        {
            SendExportFailedToClient();
        }
        else
        {
            SendExportSucceededToClient();
        }
    }

    private void SendExportFailedToClient()
    {
        Debug.Log("Export fail");
        string path = GetWorldAnchorsDataPath();
        if (File.Exists(path))
        {
            File.Delete(path);
        }
        SuccessToExportWorldAnchors(false);
    }

    private void SendExportSucceededToClient()
    {
        Debug.Log("Export succeed");
        SuccessToExportWorldAnchors(true);
    }


    private static void AppendAllBytes(string path, byte[] bytes)
    {
        //argument-checking here.

        using (var stream = new FileStream(path, FileMode.Append))
        {
            stream.Write(bytes, 0, bytes.Length);
        }
    }