How to load glb as byte[] or MemoryStream

[cpetry]

Hello,

I'd like to load a byte[] or MemoryStream as a glb file without a file path from script (not using Inspector at all).
Is this possible? Didn't find anything in examples or tests.

[pfcDorn]

hey, should be possible with public GLTFSceneImporter(GLTFRoot rootNode, Stream gltfStream, ImportOptions options), there you can set a stream

[Phlegmati]

SOLUTION

If anyone is still interested, this is how I did it for my webGL Application:

• parsing the stream for gltf root
• disabled multithreading
• loading scene synced

protected override void LoadFromBytes(byte[] data)
{
	// Dataloader with empty constructor to skip check for directory name
	var importOptions = new ImportOptions
	{
		DataLoader = new UnityWebRequestLoader("")
	};

	// Parse the stream
	GLTFParser.ParseJson(stream, out var gltfRoot);
			
	stream.Position = 0;
	var loader = new GLTFSceneImporter(gltfRoot, stream, importOptions)
	{
	        // For webGL Builds: disable multithreading
		IsMultithreaded = false
	};
		
	// Load the scene by memorystream 
	loader.LoadScene(-1, true);
}

If anyone has a better approach, please let me know!

Old Comment History

.
.
.

Original comment:
I do have the same "problem". I want to load a glb file in webGL.
After I used a filebrowser, I do get a byte[] array, which I fed into a memorystream and then created a new SceneImporter with the stream and importOptions:

IEnumerator LoadGLB(byte[] data)
{
   MemoryStream stream = new MemoryStream(data);

   var importOptions = new ImportOptions
   {
       AnimationMethod = AnimationMethod.MecanimHumanoid
   };

   var sceneImporter = new GLTFSceneImporter(
	null, 
	stream, 
	importOptions
   );

   yield return sceneImporter.LoadScene(-1, true, AfterImportFinished);
}

But at initialization, in the constructor of GltfSceneImporter the "VerifyDataLoader" Method gets called, which checks for a directoryname - which I dont have if I am using a stream as input:

    public GLTFSceneImporter(GLTFRoot rootNode, Stream gltfStream, ImportOptions options)
        : this(options)
    {
        _gltfRoot = rootNode;
        if (gltfStream != null)
        {
            _gltfStream = new GLBStream
            {
                Stream = gltfStream,
                StartPosition = gltfStream.Position
            };
        }

        VerifyDataLoader();
    }
    
    private void VerifyDataLoader()
    {
        if (_options.DataLoader == null)
        {
            if (_options.ExternalDataLoader == null)
            {
                _options.DataLoader = new UnityWebRequestLoader(URIHelper.GetDirectoryName(_gltfFileName));
                _gltfFileName = URIHelper.GetFileFromUri(new Uri(_gltfFileName));
            }
            else
            {
                _options.DataLoader = LegacyLoaderWrapper.Wrap(_options.ExternalDataLoader);
            }
        }
    }

If I am trying to use it, unity throws a NullReferenceException, because the "_gltfFileName" is empty.

For now I dont know how to use it - any recommendations?

.
.
.

EDIT: Okay I tried with the UnityWebRequestLoader but it only works in editor playmode, built to webGL it doesnt. This is my code so far, only working in Editor:

IEnumerator LoadGLB(string uri)
{
        // uri contains host and blob of my browser chosen file
	// something like: http://127.0.0.1:5500/39550693-4ad4-4e87-8856-83ac8b84ed85
	
        var importOptions = new ImportOptions
        {
            AnimationMethod = AnimationMethod.MecanimHumanoid
        };

        var sceneImporter = new GLTFSceneImporter(
	    uri,
	    importOptions
	);

	yield return sceneImporter.LoadScene(-1, true, CreatePuppetBehaviour);
}

And this was my working code for uploading a file to my WebGL APP, using a different gltf plugin, which worked by loading from byte[]:

IEnumerator LoadGLB(string uri)
{
    using UnityWebRequest uwr = UnityWebRequest.Get(uri);
    yield return uwr.SendWebRequest();
    if (uwr.error != null) Debug.Log(uwr.error);
    else
    {
        byte[] result = new byte[uwr.downloadHandler.data.Length];
        System.Array.Copy(uwr.downloadHandler.data, 0, result, 0, uwr.downloadHandler.data.Length);
        importer.LoadGLBFromBytes(result);
    }
}

I feel like something in between is missing. Maybe it needs to copy the buffer?

.
.
.

EDIT 2: Okay I am pretty sure it is the "System.Threading.Tasks" include, that WebGL can't handle.
So only Option B) is qualified, as I can handle the WebRequest download single-threaded.

A) Use the built-in UnityWebRequestLoader, but need to understand what am I missing for now (not working in WebGL)

B) Use the Stream approach, but need to work around the filename check

@pfcDorn What would you suggest?

[cpetry]

I am trying again now like this with glb files and the "fake" UnityWebRequestLoader:

private async UniTask<GameObject> LoadWithUnityGLTF(byte[] bytes)
{
    using (var stream = new MemoryStream(bytes))
    {
        var glb = GLBBuilder.ConstructFromStream(stream);
        _unityGltf.DataLoader = new UnityGLTF.Loader.UnityWebRequestLoader("");
        var importer = new UnityGLTF.GLTFSceneImporter(glb.Root, stream, _unityGltf);
        await importer.LoadScene(-1, showSceneObj: true);
        return importer.LastLoadedScene;
    }
}

But I get lots of mesh errors like these and of course no valid model:

Failed setting triangles. Some indices are referencing out of bounds vertices. IndexCount: 204, VertexCount: 80
UnityEngine.Mesh:SetIndices (int[],UnityEngine.MeshTopology,int,bool,int)

I also tried creating my own MemoryLoader with the IDataLoader interface but this didn't work as well.

private class MemoryDataLoader : UnityGLTF.Loader.IDataLoader
{
    private readonly MemoryStream _memoryStream;

    public MemoryDataLoader(MemoryStream memoryStream)
    {
         _memoryStream = memoryStream;
    }

    public async Task<Stream> LoadStreamAsync(string relativeFilePath)
    {
        return _memoryStream;
    }
}

Any ideas?

[pfcDorn]

Hey, can you take a look on this branch: https://github.com/KhronosGroup/UnityGLTF/tree/fix/load-from-stream
I made some changes, so you should only need these lines to load from a stream:

var stream = new FileStream(filePath, FileMode.Open);
var importOptions = new ImportOptions();
var importer = new GLTFSceneImporter(stream, importOptions);
await importer.LoadSceneAsync();
stream.Dispose();

Generally, you should only load GLBs which contains all textures and data. References to files would not work.
Let me know if it's working for you :)

Btw: You already has found a working solution with a custom DataLoader:

private class StreamDataLoader : UnityGLTF.Loader.IDataLoader
{
    private readonly Stream _stream;

    public StreamDataLoader(Stream stream)
    {
         _stream = stream;
    }

    public async Task<Stream> LoadStreamAsync(string relativeFilePath)
    {
        return _stream;
    }
}

  var stream = new FileStream(filePath, FileMode.Open);
  var importOptions = new ImportOptions();
  importOptions.DataLoader = new StreamDataLoader(stream);
  GLTFParser.ParseJson(stream, out var gltfRoot);
  var importer = new GLTFSceneImporter(gltfRoot, stream, importOptions);
  await importer.LoadSceneAsync();
  stream.Dispose();

[cpetry]

Works like a charm!
Thanks a lot for this.

I didn't manage to get it to work with the custom DataLoader but with your first example on the separate branch.
Please add documentation somewhere. Can be closed once merged