What is the Mixed Reality Toolkit

MRTK-Unity is a Microsoft-driven project that provides a set of components and features, used to accelerate cross-platform MR app development in Unity. Here are some of its functions:

• Provides the cross-platform input system and building blocks for spatial interactions and UI.
• Enables rapid prototyping via in-editor simulation that allows you to see changes immediately.
• Operates as an extensible framework that provides developers the ability to swap out core components.
• Supports a wide range of devices:

XR SDK Plugin (Unity XR Plugin Management Providers)	Supported Devices
Unity OpenXR Plugin (Unity 2020 or 2021 LTS) (Mixed Reality OpenXR Plugin required for certain features on certain devices)	Microsoft HoloLens 2 Windows Mixed Reality headsets Meta Quest Device running on SteamVR via OpenXR
Windows XR Plugin	Microsoft HoloLens Microsoft HoloLens 2 Windows Mixed Reality headsets
Oculus XR Plugin (Unity 2019 or newer LTS)	Meta Quest (via Oculus Integration Package)
ARCore XR Plug-in	Android (via AR Foundation)
ARKit XR Plug-in	iOS (via AR Foundation)

Additional devices supported:

• Ultraleap Leap Motion controller for hand tracking (via Ultraleap's OpenXR API layer (recommended) or via Ultraleap's Plugin for Unity)

NOTE: We have introduced the public preview of MRTK3, the next chapter of MRTK. For documentation, please go to the MRTK3 documentation. For code, please go to the mrtk3 branch.

Getting started with MRTK

If you're new to MRTK or Mixed Reality development in Unity, we recommend you start at the beginning of our Unity development journey in the Microsoft Docs. The Unity development journey is specifically tailored to walk new developers through the installation, core concepts, and usage of MRTK.

IMPORTANT: The Unity development journey currently uses MRTK version 2.8.2, Mixed Reality OpenXR plugin version 1.6.0 and Unity 2020.3.42+.

If you're an experienced Mixed Reality or MRTK developer, check the links in the next section for the newest packages and release notes.

Documentation

Starting from MRTK 2.6, we are publishing both conceptual docs and API references on docs.microsoft.com. For conceptual docs, please visit our new landing page. For API references, please visit the MRTK-Unity section of the dot net API explorer. Existing content will remain here but will not be updated further.

Release Notes	MRTK Overview	Feature Guides	API Reference

Build status

Branch	CI Status	Docs Status
main

Required software

Windows SDK	Unity 2018/2019/2020 LTS	Visual Studio 2019	Emulators (optional)

Please refer to the Install the tools page for more detailed information.

Feature areas

Input System	Hand Tracking (HoloLens 2)	Eye Tracking (HoloLens 2)	Profiles	Hand Tracking (Ultraleap)
UI Controls	Solvers	Multi-Scene Manager	Spatial Awareness	Diagnostic Tool
MRTK Standard Shader	Speech & Dictation	Boundary System	In-Editor Simulation	Experimental Features

UX building blocks

Button	Bounds Control	Object Manipulator
A button control which supports various input methods, including HoloLens 2's articulated hand	Standard UI for manipulating objects in 3D space	Script for manipulating objects with one or two hands
Slate	System Keyboard	Interactable
2D style plane which supports scrolling with articulated hand input	Example script of using the system keyboard in Unity	A script for making objects interactable with visual states and theme support
Solver	Object Collection	Tooltip
Various object positioning behaviors such as tag-along, body-lock, constant view size and surface magnetism	Script for laying out an array of objects in a three-dimensional shape	Annotation UI with a flexible anchor/pivot system, which can be used for labeling motion controllers and objects
Slider	MRTK Standard Shader	Hand Menu
Slider UI for adjusting values supporting direct hand tracking interaction	MRTK's Standard shader supports various Fluent design elements with performance	Hand-locked UI for quick access, using the Hand Constraint Solver
App Bar	Pointers	Fingertip Visualization
UI for Bounds Control's manual activation	Learn about various types of pointers	Visual affordance on the fingertip which improves the confidence for the direct interaction
Near Menu	Spatial Awareness	Voice Command / Dictation
Floating menu UI for the near interactions	Make your holographic objects interact with the physical environments	Scripts and examples for integrating speech input
Progress Indicator	Dialog [Experimental]	Hand Coach
Visual indicator for communicating data process or operation	UI for asking for user's confirmation or acknowledgement	Component that helps guide the user when the gesture has not been taught
Hand Physics Service [Experimental]	Scrolling Collection	Dock [Experimental]
The hand physics service enables rigid body collision events and interactions with articulated hands	An Object Collection that natively scrolls 3D objects	The Dock allows objects to be moved in and out of predetermined positions
Eye Tracking: Target Selection	Eye Tracking: Navigation	Eye Tracking: Heat Map
Combine eyes, voice and hand input to quickly and effortlessly select holograms across your scene	Learn how to auto-scroll text or fluently zoom into focused content based on what you are looking at	Examples for logging, loading and visualizing what users have been looking at in your app

Tools

Optimize Window	Dependency Window	Build Window	Input recording
Automate configuration of Mixed Reality projects for performance optimizations	Analyze dependencies between assets and identify unused assets	Configure and execute an end-to-end build process for Mixed Reality applications	Record and playback head movement and hand tracking data in editor

Example scenes

Explore MRTK's various types of interactions and UI controls through the example scenes. You can find example scenes under Assets/MRTK/Examples/Demos folder.

MRTK examples hub

With the MRTK Examples Hub, you can try various example scenes in MRTK. On HoloLens 2, you can download and install MRTK Examples Hub through the Microsoft Store app.

See Examples Hub README page to learn about the details on creating a multi-scene hub with MRTK's scene system and scene transition service.

Sample apps made with MRTK

Periodic Table of the Elements is an open-source sample app which demonstrates how to use MRTK's input system and building blocks to create an app experience for HoloLens and Immersive headsets. Read the porting story: Bringing the Periodic Table of the Elements app to HoloLens 2 with MRTK v2	Galaxy Explorer is an open-source sample app that was originally developed in March 2016 as part of the HoloLens 'Share Your Idea' campaign. Galaxy Explorer has been updated with new features for HoloLens 2, using MRTK v2. Read the story: The Making of Galaxy Explorer for HoloLens 2	Surfaces is an open-source sample app for HoloLens 2 which explores how we can create a tactile sensation with visual, audio, and fully articulated hand-tracking. Check out Microsoft MR Dev Days session Learnings from the Surfaces app for the detailed design and development story.

Session videos from Mixed Reality Dev Days 2020

Tutorial on how to create a simple MRTK app from start to finish. Learn about interaction concepts and MRTK’s multi-platform capabilities.	Deep dive on the MRTK’s UX building blocks that help you build beautiful mixed reality experiences.	An introduction to performance tools, both in MRTK and external, as well as an overview of the MRTK Standard Shader.

See Mixed Reality Dev Days to explore more session videos.

Engage with the community

• Join the conversation around MRTK on Slack. You can join the Slack community via the automatic invitation sender.

• Ask questions about using MRTK on Stack Overflow using the MRTK tag.

• Search for known issues or file a new issue if you find something broken in MRTK code.

• For questions about contributing to MRTK, go to the mixed-reality-toolkit channel on slack.

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

Useful resources on the Mixed Reality Dev Center

Discover	Design	Develop	Distribute
Learn to build mixed reality experiences for HoloLens and immersive headsets (VR).	Get design guides. Build user interface. Learn interactions and input.	Get development guides. Learn the technology. Understand the science.	Get your app ready for others and consider creating a 3D launcher.

Useful resources on Azure

Spatial Anchors	Speech Services	Vision Services
Spatial Anchors is a cross-platform service that allows you to create Mixed Reality experiences using objects that persist their location across devices over time.	Discover and integrate Azure powered speech capabilities like speech to text, speaker recognition or speech translation into your application.	Identify and analyze your image or video content using Vision Services like computer vision, face detection, emotion recognition or video indexer.

Learn more about the MRTK project

You can find our planning material on our wiki under the Project Management Section. You can always see the items the team is actively working on in the Iteration Plan issue.

How to contribute

Learn how you can contribute to MRTK at Contributing.

For details on the different branches used in the Mixed Reality Toolkit repositories, check this Branch Guide here.