Have you ever considered changing your preferred VR SDK? Are you curious about what you have been missing out on by not selecting another VR Interaction SDK for your project (especially after the release of Meta's new Presence Platform and VR Interaction SDK)? This article will give you the overview you need to decide about your best choice for your next VR Development project. 

Have you recently started to implement Unity VR SDKs? Are you a beginner learning about Virtual Reality tools, software, and software development kits? Have you maybe followed our Unity VR tutorial on how to get started with Unity VR development? Now, you're probably ready to take the next step. You have started your VR or AR project with Unity, maybe even a VR Game Development project, and you've already downloaded the Unity Hub, created your project, opened it, connected your VR device, and imported your 3D models.

Now you're asking yourself how to get started with VR Interactions and are looking for VR tools. How will the user of your VR app or game interact with the digital world you have created? This is the “magic” of your future VR or AR application.

already been working with, with another one you may be working with in the future. In addition, you may be curious which features Meta has added to their recently launched Interaction VR SDK, and how it compares to the previously existing ones.

There are many new releases, updates and new Interaction SDKs popping up every day. That's why we created an Interaction SDK Knowledgebase on Notion, where we are regularly tracking and adding new frameworks and features constantly. If you would like to add your comments, or input, or wish to just get access to the VR Interactions SDK Overview Table, feel free to submit your e-mail - we will send you the link.

VR SDKs are great Virtual reality tools and a way to easily implement tons of pre-built and configured interactions in your XR project such as grabbing objects, interacting with UI, recognizing hand gestures, etc.

Interactions are simply the core of the XR experience. We can have an incredible world that we created, perfectly tracked hands that match our real hands, beautiful visuals and sound… but what makes XR really outstanding is how we can interact with the world around us.

This is what makes designing interactions difficult and so important in VR. More than any other medium, VR interactions are centered around your physical surroundings and senses. "Immersive" or "real" experience in virtual reality are the keywords we think about interactions. No matter how fantastic your VR app is, having grounded interactions that make the user feel comfortable in the environment is essential. It could be the difference between "fun" and "boring."

Some of the main interactions you should be looking for in a good Interactions SDK, are:

UI Interactions: 

We will definitely need menus and setting screens in our experience or game, and good and reactive UI components are a must.

Locomotion: 

Locomotion refers to the ability we have to move inside the virtual world, for example teleporting to a different place, or using the controllers (or hand tracking gestures) to continuously move through the environment.

Here are some of the most important criteria you should consider before choosing your VR SDK for Unity, but remember, these criteria are also conditioned by your use case. For example, if you are building a game, you might want to focus on controller support, physics interactions, locomotion, etc. On the other hand, if you’re looking into building an educational experience, you will prioritize interactions such as hand tracking, UI, multiple target devices, etc.

• Multiple XR target devices: if the SDK lets us build to different devices/platforms easily.
• Target XR environment: if we can build VR, AR, MR, etc.
• Development engine/IDE: Unity, Unreal, etc.
• Implementation difficulty level: How difficult is it to the interaction and features in our project?
• Development activity and source code access: When you choose an SDK, it is very important to check what’s the activity of the development, if its source code is open, and to get a general idea on who is behind it to make sure the framework is guaranteed to exist in the following years.
• OpenXR support: OpenXR is a royalty-free, open standard, that manages the communication between the game engine and the devices. If you want your game/app to be future proof, it is important to consider it.
• Physics interactions: if the SDK includes physics interactions support or examples.
• Hand tracking support: if the SDK has support for handling tracking our hands using, for example, the external cameras of the device.
• Device/Action based: Is the SDK detecting inputs based on the device (Oculus Quest, HTC Vive, HoloLens) or is the detection based on the action (Select - grip button pressed - , Activate - trigger button pressed -  etc.)?
• Interaction controller samples: e.g.: left/right hand controller with hover, select and activate inputs pre-configured
• UI Interactions: Does the SDK provide UI interactions support and samples?
• Locomotion: If the SDK includes support for locomotion systems as teleporting, or controller continuous movement.
• Two hand based interactions: does the SDK provide support for interactions using both hands at the same time? For example, grabbing an object with both hands at the same time, and scaling it.
• Official Toolkit website & community: webpages for manuals, documentation and community.

Now that we know the criteria, we’ll have a look at some of the most used SDK's out there:

The XR Interaction Toolkit (Unity's official XR interaction toolkit, recently out of preview phase, meaning that Unity considers it to be good enough for production.), the MRTK (Microsoft’s official MR (Mixed Reality) toolkit, originally released for Hololens development, but then extended to other platforms), the VRTK (The virtual reality toolkit was one of the first widely adopted tool kits/SDK for VR development with Unity. Low code and beginner-friendly), the Oculus Interaction SDK (Official SDK from Oculus. It is focused on developing for Meta/Oculus devices), the XRTK (The XR Tool Kit is a community-supported fork of Microsoft’s MRTK. The XRTK differs from the MRTK with its heavy focus on efficient architecture and lightweight SDK that promotes additional expandability but may be more difficult for beginners due to the lack of sample scenes.

To help you choose, and to give you a better overview over the VR SDKs for Unity, we prepared the following comparison table looking at all previously mentioned criteria.

There are many new releases, updates and new Interaction SDKs popping up every day. That's why we created an Interaction SDK Knowledgebase on Notion, where we are regularly tracking and adding new frameworks and features constantly. If you would like to add your comments, or input, or wish to just get access to the VR Interactions SDK Overview Table, feel free to submit your e-mail - we will send you the link.

The XR InteractionToolkit is a Unity VR tool. It is part of Unity's XR Plugin Architecture (XR Tech Stack), and it contains a set of components that allow you to create quick and easy XR interactions with minimum effort. Also, it uses Unity's Input System to identify the input events. More info about XRIT here

Source: Unity - Manual: XR Plug-in Framework

Here’s a tutorial about how to use  Interactions and Locomotion with this VR SDK for Unity:  here

The Mixed Reality Toolkit (MRTK) is a Microsoft-driven project that provides a set of components and features, used to accelerate cross-platform MR app development in Unity. 

If you’re interested in exploring the MRTK further, check our HoloLens & Mixed Reality Master Class here.

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 platforms.

In both most used versions (v3 and v4), you can find a big scene including examples, which is very useful to build your first VR experiences, as you can “drag and drop” the examples into your own projects and adapt them to your own personal use.

Oculus Integration SDK, which is also an Oculus dev kit, provides a good amount of tools and features out of the box. They update the kit quite often, and new exciting features are being added very frequently (this can lead to the toolkit being unorganized and outdated). The last SDK update, v37, featured the Interactions SDK, which presents new tools to build more complex and richer interactions. 

Since v31 (August 2021), OpenXR is the main API behind the SDK, meaning that new features will be delivered through this standard. For example, the passthrough feature is exclusive to OpenXR and it is not supported with the old mobile or pc APIs.

The XRTK is a fork of Microsoft’s MRTK. The XRTK is also pronounced “Mixed Reality Toolkit.” The XRTK fork was a result of a schism that occurred between the MRTK developers from Microsoft and non-Microsoft MRTK contributors regarding the Mixed Reality Toolkit’s ideology, architecture, and contribution process. 

XRTK's vision is simple, to provide a complete cross-platform solution for AR/XR/VR development that supports three different developer skill levels:

• Beginner No Coding Required: Perfect for artists, Hackathons, and Quick Prototyping.
• Intermediate Customizable: The framework is flexible enough so coders can customize what they need to cover edge cases with ease.
• Advanced Extensible: The framework is easy to extend and modify to add additional custom services to meet specific criteria and needs.

All VR SDKs for Unity have their pros and cons. It comes down to what works best for you, depending heavily on your use case and target platforms you wish to build for.

If you are looking into building a VR game in multiple XR platforms, we recommend going for Unity’s XR Interaction Toolkit as this VR SDK for Unity focuses on controllers, locomotion, and physics interactions. It provides a lot of compatibility with other Unity assets, the ability to build to multiple devices and platforms, the possibility to build AR experiences, and it includes OpenXR support.

Oculus Integration SDK is great if you plan to only create products for the Meta platform. You get access to the cutting-edge features that Meta develops such as hand-tracking and Meta avatars, as well as many of the new updates that Meta plans to release down the line. Oculus is currently the most widely used VR platform. So choosing Oculus Integration is a good pick if you know that you will be primarily on the Oculus platform. That said if you are looking for a more multi-platform use case we still suggest XR Interaction Toolkit for now. 

For non gaming purposes, such as educational or enterprise experiences, you should be looking into using either MRTK or XRTK , as they are heavily focused on hand tracking and UI components. Microsoft has done an amazing job creating UI design tools for this next generation of spatial computing.

This article has been written by: 

• Jonathan Lourie, Hernando Nieto, and Lucas Martinic, VR Developers and Content Creators at XR Bootcamp
• Sean Ong, Hololens & Mixed Reality Master Class Trainer at XR Bootcamp

In case you have any questions about this article or VR SDKs in general, feel free to reach out at mentors@xrbootcamp.com.

There are many new releases, updates and new Interaction SDKs popping up every day. That's why we created an Interaction SDK Knowledgebase on Notion, where we are regularly tracking and adding new frameworks and features constantly. If you would like to add your comments, or input, or wish to just get access to the VR Interactions SDK Overview Table, feel free to submit your e-mail - we will send you the link.