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Mixed Reality Extension SDK Unity

The Mixed Reality Extension SDK Unity library makes it easy for any Unity3D app or game to support user generated content (UGC) built with the Mixed Reality Extension SDK. It also makes it easy to test an MRE within a simple environment inside the Unity3D editor.


  • Install Git
  • Use Unity Hub to Install Unity 2018.1.9f2 (or later) - Set environment variable UNITY_ROOT to the installation path.
  • Install Visual Studio 2017, including Visual Studio Tools for Unity and .NET development tools

How to build and run Hello World in the Unity3D editor

From command prompt:

  • git clone
  • Run buildMREUnityRuntimeDLL.bat
  • Open Unity3D, project folder mixed-reality-extension-unity/MRETestBed
  • open the scene Assets/Scenes/HelloWorld.unity
  • click play You should now see a slowly spinning Hello World label and a clickable cube.

Scene Descriptions

The MRETestbed project contains 4 Unity3d scenes set up for different testing purposes

  • HelloWorld.Unity: Connects to a single MRE in the cloud on startup, no interaction needed
  • FunctionalTest-localhost.Unity. Requires a locally deployed functional test MRE from the SDK Repository. Generates a launch pad for each of the functional tests - just walk close to trigger them. Or touch the "run all" trigger to load every single functional test. There is also a pad for changing the global root - it moves, scales, and rotates everything in the world, which simplifies checking the 3d math.
  • TriggerVolumeTestBed-localhost.Unity: Connects to a localhost MRE when you walk close - useful for testing user join/leave.
  • SynchronizationTest-localhost.Unity: Connects twice to twice to a localhost MREs with the same session ID. When you click on the two spheres you will see 2 different connections to the same server, so you can perform basic multiuser testing without multiple machines or multiple unity instances.

The Localhost samples requires a local node server running, see the Sample repository for localhost deployment.

To Debug the Unity Runtime DLL

  • From within the Unity3D editor click Assets->Open C# Project. This opens Visual Studio and generates a solution file and project files
  • In the Solution Explorer, right click on Solution 'MRETestBed' (3 projects), click Add->Existing Project..., and select MREUnityRuntime\MREUnityRuntimeLib\MREUnityRuntimeLib.csproj
  • Press play in the editor
  • Select Debug->Attach Unity Debugger (requires the Visual Studio Unity Tools installed to show up), and choose Project MRETestBed, type Editor

Putting breakpoints inside the MREUnityRuntimeLib DLL is not always working, but pressing stop in Unity Editor, rebuilding the MREUnityRuntimeLib project in Visual Studio, and pressing play in the Unity Editor tends to fix it.

Integration guide

If you want to integrate the MRE SDK into your own Unity3D project, please see


  • For more information, please see the Mixed Reality Extension SDK repository's is the best source of information about features, current state, limitations, goal, major known issues, and roadmap.
  • We welcome contributions. Please see if you are interested in helping out.

Getting In Touch

To report issues and feature requests: Github issues page.

To chat with the team and other users: join the MRE SDK discord community.

Or attend the biweekly AltspaceVR developer meetups.

Reporting Security Issues

Security issues and bugs should be reported privately, via email, to the Microsoft Security Response Center (MSRC) at You should receive a response within 24 hours. If for some reason you do not, please follow up via email to ensure we received your original message. Further information, including the MSRC PGP key, can be found in the Security TechCenter.


Code licensed under the MIT License.

Code of Conduct

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact with any additional questions or comments.


The Mixed Reality Extension Unity library is an easy way for developers to add User Generated Content (UGC) capabilities to their Unity3D-based host apps





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