What is Mixed Reality Toolkit 2?

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 Plugin 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

Note

We have introduced the public preview of MRTK3, the next chapter of MRTK. For more information, please go to the MRTK3 documentation.

Getting started with MRTK

If you're new to MRTK or Mixed Reality development in Unity, we recommend installing and exploring the MRTK Examples Hub sample application on your device or emulator.

Download the MRTK Examples Hub app

Once you've got the hang of what Mixed Reality and MRTK has to offer, install the necessary tools and follow our beginner level HoloLens 2 tutorial series.

Install the tools

HoloLens 2 Tutorial Series

Want to see what's going on under the hood?

Explore MRTK on GitHub

Documentation

Release Notes	MRTK Overview	API Reference

Build status

Branch	CI Status	Docs Status
main

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 Example View

Speech
& Dictation

Boundary
System

In-Editor
Simulation

Experimental
Features

UX building blocks

Button
A button control which supports various input methods, including HoloLens 2's articulated hand

Bounds Control
Standard UI for manipulating objects in 3D space

Object Manipulator
Script for manipulating objects with one or two hands

Slate
2D style plane which supports scrolling with articulated hand input

System Keyboard
Example script of using the system keyboard in Unity

Interactable
A script for making objects interactable with visual states and theme support

Solver
Various object positioning behaviors such as tag-along, body-lock, constant view size and surface magnetism

Object Collection
Script for laying out an array of objects in a three-dimensional shape

Tooltip
Annotation UI with a flexible anchor/pivot system, which can be used for labeling motion controllers and objects

Slider
Slider UI for adjusting values supporting direct hand tracking interaction

MRTK Standard Shader
MRTK's Standard shader supports various Fluent design elements with performance

Hand Menu
Hand-locked UI for quick access, using the Hand Constraint Solver

App Bar
UI for Bounds Control's manual activation

Pointers
Learn about various types of pointers

Fingertip Visualization
Visual affordance on the fingertip which improves the confidence for the direct interaction

Near Menu
Floating menu UI for the near interactions

Spatial Awareness View
Make your holographic objects interact with the physical environments

Voice Command
Scripts and examples for integrating speech input

Progress Indicator
Visual indicator for communicating data process or operation

Dialog
UI for asking for user's confirmation or acknowledgement

Hand Coach
Component that helps guide the user when the gesture has not been taught

Hand Physics Service [Experimental]
The hand physics service enables rigid body collision events and interactions with articulated hands

Scrolling Collection
An Object Collection that natively scrolls 3D objects

Dock [Experimental]
The Dock allows objects to be moved in and out of predetermined positions

Eye Tracking: Target Selection
Combine eyes, voice and hand input to quickly and effortlessly select holograms across your scene

Eye Tracking: Navigation
Learn how to auto-scroll text or fluently zoom into focused content based on what you are looking at

Eye Tracking: Heat Map
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

MRTK provides example scenes that demonstrate how to use MRTK's features. You can find the example scenes under Assets/MRTK/Examples/Demos folder. Read the Example scenes page to learn how to acquire and run example scenes. Hand Interaction Examples scene is a great place to start experiencing MRTK's building blocks for interactions and UI.

MRTK examples hub

With the MRTK Examples Hub, you can try various example scenes in MRTK without building and deploying each scene. You can download pre-built app packages for HoloLens(x86), HoloLens 2(ARM), and Windows Mixed Reality immersive headsets(x64) by selecting the "Mixed Reality Toolkit Examples" package in the MR Feature Tool. Make sure to use the Windows Device Portal to install apps on HoloLens (1st gen). 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 opencode@microsoft.com with any additional questions or comments.

Useful resources on 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.

How to contribute

Learn how you can contribute to MRTK at Contributing.

Getting help

If you run into issues caused by MRTK or otherwise have questions about how to do something, there are a few resources that can help:

• For bug reports, please file an issue on the GitHub repo.
• For questions, please reach out on either StackOverflow or the mixed-reality-toolkit channel on Slack. You can join the Slack community via the automatic invitation sender.