A simple viewer for GLTF files on HoloLens, present in the Windows Store here.
The viewer is speech driven, the user is prompted to say "open" to select a file from their 3D objects folder which the viewer then presents a few metres in front of the user and they can use hand gestures to scale, rotate, translate the model followed by saying "reset" to put it back where it originally was. They can then use "open" to open some more models.
The app also has a basic 'shared holographic' (or 'Multi-Lens') capability. Whenever a user opens a model on one device, the app multicasts around the network and other devices will display a "would you like to open this model" dialog.
If the secondary user says "yes" then their device will use HTTP to talk to a web server running on the first device to request all the files that make up the model which will then be copied to the secondary device and the model will then be opened from there. A spatial anchor will also be exported, requested and imported on the secondary device such that the object will appear in the same place in the physical world as it was on the originating device.
Lastly, from hereon in, any movements on the originating device will be replicated to the secondary device(s) until a device breaks the link by using the "open" command again or perhaps accepting a model from another device.
This allows for a shared holographic experience without having any form of local or cloud server to provide infrastructure.
In terms of what's in this repo - it's not perfect in that it needs a step or two to make it build.
First, clone the repo with --recursive in order to bring down the Mixed Reality Toolkit for Unity as part of the clone along with UnityGLTF.
Then, you need to move into the GLTFModelViewer folder and run;
setup.bat
It uses relative paths so ensure that it's run from that folder.
There's a challenge in that I want to use the Mixed Reality Toolkit (MRTK) and Unity GLTF support but the MRTK has parts of the Unity GLTF support already embedded within it including scripts and binary plugins.
This means that, by default, I get duplication of the UnityGLTF plugins and some of the scripts (both of which are different across MRTK and UnityGLTF).
My solution is to get rid of the GLTF pieces embedded in the MRTK but this does leave a script (MotionControllerVisualizer.cs) in a broken state so I also remove that script and have in my assets a 'dummy' replacement script which avoids the dependency on GLTF which I don't need anyway as I am targeting HoloLens.
Beyond that, the script also compiles the UnityGLTF serialization pieces, tries to put the resulting DLLs into the right places and removes a few pieces which, again, cause me problems & aren't needed here.
The script is quite brittle right now and is likely to break as the underlying frameworks get versioned. It also uses nuget.exe and msbuild so please make sure they are on your path.
Note, at the end of the script it's highly likely that DLL metadata isn't quite right in Unity so you'd need to open up the project in Unity, apply Mixed Reality Toolkit settings to the project (via the menu) and then visit these 2 DLLs.
Assets\UnityGLTF\Plugins\UWP\GLTFSerializationUWP.dll - should be marked for only the UWP platform & SDK.
Assets\UnityGLTF\Plugins\UWP\GLTFSeriazliation.dll - should be marked for the editor only.
Note also that within Unity I seem to lose my UWP capability settings which are in the "Publishing Settings" part of the UI. This application needs Internet Client, Internet Client/Server, Private Networks, Microphone, Spatial Perception and the 3D Objects folder. Some of these seem to get lost, perhaps I haven't tracked a file that Unity uses.
Note also that at the end of the Unity->Visual Studio->Make Appx Packages step it's possible that you have to rename two or three .png files to make the appx packager happy as, at the time of writing, I haven't quite figured how to get Unity to do what I want there but it largely involves removing the word 'logo' from 3-4 .png files that come out of Unity.