DEV Community: Chel_Koby

VR SDKs Comparison to give you a Headstart in VR Development

Chel_Koby — Fri, 26 Feb 2021 17:44:01 +0000

Starting VR Game Development is a thrill and at the same time a cold chilling ordeal. You want to make beautiful games, you are confident of your creative abilities, one little hitch though - you have no idea where to start, what to use, or even why to use them. In this tutorial, I drastically simplify the entire process in my most preferred way of communication - layman terms. Are you with me?, well, then Read On!.

What are VR SDKs/Plugins?

NOTE: This post is focused on implementation with the Unity 3d engine as it is best suited for beginners (from experience). if by chance, your heart lies with Unreal, worry not, the plugins' name can be easily tweaked for Unreal Engine. You would understand better my meaning as we progress.

You have no doubt heard constantly about VR SDKs and plugins. As a beginner to Vr development, perhaps with no previous experience with APIs and Plugins, these terms might all seem very strange and confusing to you. The good news for you is that it shouldn't anymore after reading this article, my goal is to simplify the idea around them in simple words.

VR SDKs (Virtual Reality Software Development Kits) are a collection of scripts (Long gist of Codes), prefabs, components, and packages, i.e all accumulated into one single Unity "Asset" - the purpose is to make the building of VR experiences easier for the end-user. Let's take a different perspective to understand better;

In a Virtual reality Game or Experience, We (Users) can involve in a lot of basic to advanced interactions, most similar to how our natural behavior in the real world, example is (looking around yourself, walking, running, picking, grabbing, and throwing objects) - All these we can do in a VR world, Normal 3d games are limited to devices. The fact that these new actions mentioned above are possible in VR means there must be new ways to create them, and usually, the efforts and coding skills required are too advanced for the majority of developers like you are me ..... And we have VR SDKs; Simply a set of predefined scripts that aid us in developing. This approach should give you a much better idea of the whole concept.

How many Plugins do we have

In Unity, there are several SDKs for VR development, the reason being to accommodate support for various headsets and controllers. As new brands release their unique VR headsets, we see inevitably the introduction of their SDK published to simply the development process for their unique platform. Some SDKs support a wide range of headsets while others don't. We are going to talk about these two variations and what SDKs exist for them;

Right now, I can't say accurately how many SDKs for the Unity Platforms, probably because one is usually released now and then, but for sure, we have some popular ones common among the majority of developers:

Open VR Unity Plugin: OpenVR is a software development kit (SDK)developed by Valve for supporting the SteamVR (HTC Vive) and other virtual reality headsets (VR) devices. (Meaning that Using Open XR in Unity for VR Dev, all other headsets can access VR content created with it) The SteamVR platform uses it as the default application programming interface (API) and runtime. It handles display, tracking, and input for Open VR devices.
Unity XR Interaction Toolkit: The Unity XR Interaction Toolkit is a Package Provided by Unity for creating VR, AR Experiences. It provides a framework that makes VR and UI interactions available from Unity input events(Keyboards, Gamepads, and Controllers, etc.). The core of this system is a set of base Interactor and Interactable components and prefabs and an Interaction Manager that enables the relative working of these two components. It also contains helper components that you can use to extend functionality for drawing visuals and hooking in your interaction events. It can be used in both VR and AR Instances and comes with different functions, scripts, and classes for building gameplay.
The Unity XR Interaction Toolkit is a very new package released in the fall of 2019 to take the place of popular VR and AR Plugins like the HTC Vive Utility plugins, Oculus VR Plugin, VRTK, etc. The goal is to provide a framework that allows simple integration of different VR SDKs, i.e (Building experiences that can be tailored to different standalone/ VR Headsets without hassles). Without diving into the details - The XR Interaction toolkit works to detect the device plugged in and switches functionality to it solely.
Among the Plugins listed, the UIT is currently the easiest way to build VR Experiences, while not the most feasible as it's still in preview release but holds unity support fully. For Developers completely new to VR dev and aiming for fast progress, this package can be used to familiarise with. It also supports the integration of third-party SDKs found on the unity assets store to build realistic experiences. To get started with this, read this guide Unity XR Toolkit - Important points to Note
VRTK: VRTK is a collection of useful, reusable solutions to common problems found when building for virtual reality. VRTK aims to help productivity by speeding up the creation process from prototyping ideas to building complete solutions.
The VRTK Unity Plugin brings a whole lot of functionalities with a Drag-and-Drop System. It allows compatibility with a set of popular VR SDKs like Oculus Plugin, Steam VR Plugin, and even for Open VR.
The full list of Compatible Unity VR Plugins with VRTK and their Uses are listed below;
- Oculus VR SDK: For Targeting Oculus VR Headsets(Quest, Quest2)
- Steam VR SDK: For Targeting Steam VR (SteamVR Platform on Steam)
- DayDream VR SDK: For Targeting Daydream VR Headsets(Google Daydream)
- Windows MR SDK: For Targeting Windows Mixed Reality
- HyperReal VR SDK
- Simulator SDK: As a Mock HMD, VR without a Headset
- Ximmerse SDK If you wanna explore deeper using VRTK, ensure to follow this guide, take it from me - there are countless errors to run into VRTK for Vr Development
Oculus Integration Plugin: Unity provides built-in VR support for Oculus devices. The Oculus Integration package adds scripts, prefabs, samples, and other resources to supplement Unity’s built-in support. The package includes an interface for controlling VR camera behavior, a first-person control prefab, a unified input API for controllers, rendering features, debugging tools, and more.
The Oculus Integration package, OculusIntegration.unitypackage, is available for download from the Unity Asset Store using this link Oculus Integration Software/SDK
Before you import the package in unity, check the hardware, software, and Unity version requirements. The minimum supported Unity Editor version for Oculus development is 2018.4.
Open XR Unity Plugin: I left this for the least Plugin so as not to cause confusion among readers. Do you feel like we already mentioned this?. Go ahead and scroll up to identify the Difference.

...

Yeah!. The former is the Open 'VR' Plugin and this is the Open 'XR'. So what's the difference. Very Simple; The Open XR must be used with Unity's new XR Plugin Management. Confused?, Pls don't be. let me shed some light.

Unity alas, has chosen to refer to VR content as XR, since they strongly believe their engine is more than capable of building AR experiences. So instead of lone VR, it's now referred to as XR. The Plugin Management is just straightforward: The Plugin Management. A way to manage the various plugins installed in a unity project. The image below shows how this management system looks. It checks and unchecks boxes to notify you of which XR Plugin installed is currently active. One of the main purposes of this system is to enhance "multi-platform development and publishing", i.e When you are targeting several VR hardware for your content, you can install their SDKs and manage it with the Plugin Manager.

Now, why leave this important information for the last part, because there's a whole new world for you to uncover?, Or just Read? 😶. That's where the Open XR comes in, practically invades.
The Open XR Plugin is one of those SDKs that can be used with the XR Plugin Management and what is it?

It's shares similarities with the Open VR Plugin in that it can be used for multi-platform development. It supports head tracking, display but... it ends there. Yeah, this is a relatively new plugin, still in preview mode, and no suitable interaction/input system method(grabbing, throwing, teleportation) is currently supported. It can be used by itself or integrated with steam VR for full input support. Still, you can choose for hooking up input systems between the input Steam VR Plugin or Unity XR Interaction toolkit. Only one can be used at a time, both aren't compatible. A detailed guide is coming soon on how to set this up on unity, but if you want to test the waters urself, you can follow this link to download the preview version Open XR Unity SDK.

XR Plugin Management Compatible SDKs

After a briefing on the XR Management and how Open XR is compatible with it, I want to pass across an important point to note:

By using the XR Plugin Management, You CANT use Standalone SDKs like (Steam VR, Oculus VR, Open VR, etc). And likewise, by using any of the standalone SDKs you can make use of the XR Plugin Management Tool in your Project. You either use one. Open XR as we have seen is a compatible plugin, what other SDKs exist that are compatible, below they are listed with a singular way of installing them;

Oculus XR Plugin
Windowsmr XR Plugin
Mock HMD XR Plugin
Oculus Android Plugin

The common way to install them among your project's package is Goto Windows > Package Manager > Search for Individual Names > Click Install in the bottom right corner.

After this detailed summary of the various VR SDKs/ XR SDKs, can you Identify those requiring usage for special hardware and those that can be used for multiple platform development? If you can't, I've failed as a developer and writer 🤔. Ah, let's leave that for later, we shall see

Which of Them?

You read enough, in fact, you deserve a congratulatory message, drop your email and that would be attended to. I mean, you've read enough of them theory, your teeth must be craving for just some practice. Lucky, I made the necessary plans for that. Among the various SDKs Listed, you probably have a favorite already, but is that the most suited for you. Read On, In this section, we talk about choosing an SDK to start Development along with consideration of some Factors:

The easiest SDK: UIT
The most profitable: Open XR & Open VR
Suited for Professionals: Steam VR & Oculus VR
Unity's Recommendation: Possibly Open XR

Feedback

Now it's been quite a long informative guide on the various VR SDKs that exist for Unity VR Development. As I said earlier in the article, if you are rather going to be developing using Unreal Engine, for all SDKs mentioned, I have provided links in case you want to download it. The components and features remain the same, the only difference being that the name unreal is used instead of unity.

VR SDKs for Unreal Engine

Steam VR for Unreal EngineHere
Unreal Engine has Built-in Support for Oculus VR
VR Expansion Plugin - Like VRTK but for Unreal Here
Setting up Open XR in Unreal Engine Here

Right back on track and i have a little task for you; Can you identity SDKs which are multi-platform and those that are compatible with specific devices? Leave your answer in the comments box below!. I can't wait to see how your mind works 🙃

Set up Unity XR Interaction Toolkit for VR Development: Important Points to Note

Chel_Koby — Wed, 17 Feb 2021 18:47:47 +0000

About the Unity Interaction Toolkit

The Unity XR Interaction Toolkit is a Package Provided by Unity for creating VR, AR Experiences. It provides a framework that makes VR and UI interactions available from Unity input events(Keyboards, Gamepads, and Controllers, etc.). The core of this system is a set of base Interactor and Interactable components and prefabs and an Interaction Manager that enables the relative working of these two components. It also contains helper components that you can use to extend functionality for drawing visuals and hooking in your interaction events. It can be used in both VR and AR Instances and comes with different functions, scripts, and classes for building gameplay.

The Unity XR Interaction Toolkit is a very new package released in the fall of 2019 to take the place of popular VR and AR Plugins like the HTC Vive Utility plugins, Oculus VR Plugin, VRTK, etc. The goal is to provide a framework that allows simple integration of different VR SDKs, i.e (Building experiences that can be tailored to different standalone/ VR Headsets without hassles). Without diving into the details - The XR Interaction toolkit works to detect the device plugged in and switches functionality to it solely.

One thing to Note but which isn't the focus of this tutorial is that the XR Interaction Toolkit is part of the XR Plugin Management which in whole refers to all Plugins and SDKs that can be mapped and integrated with the XR Interaction Toolkit for VR Development. Later in this tutorial, We are gonna look at some of them like the Oculus XR Plugin.

Now I can go on with more explanation but, a much better way for you to grasp the whole concept involved is through visualization and hands-on testing. For this reason, In the next section, we look at how to install and open in Unity a Starter template that uses the XR Interaction Toolkit for VR development.

Installation of Unity's XR Interaction Toolkit Starter Template

Now we are gonna install the Starter Template which we are later going to open in Unity before we can start understanding each component in detail, to begin, follow the steps below or even the Guide video;

Download the XR Interaction Toolkit Starter Template from this Repo Link Link
Extract the Folder Using Windows File Explorer or any other third party software
After extraction - Copy the VR folder inside the Xr interaction toolkit file out to another location and Rename it e.g Downloads
Open up Unity Hub and Click the Add Projects Button - When Prompted select the recent VR project folder you extracted
You would need to select a particular unity version for opening this project - Anything from LTS 2019.4 - 2020 versions should work fine.

When Unity opens fully, Go to the Scenes folder in the Projects tab and open the "World Interaction Scene" If you follow the listed steps correctly, in the scene view you should see something like below. If that isn't the case for you, please leave a comment below and I will be glad to help. Some of the common problems that arise are (pink screen, error in the console, etc).

Now that you have it opened up, we can move on to the more juicy part of this article 😉; Explaining what is happening on the screen and how to set up for a VR project. Let's quickly get down to it

Features of UIT (From now on UIT means Unity XR Interaction Toolkit)

By features, what do I mean? I mean this; What can you as a developer achieve with UIT. In this section, I hope to give you a general to specifics scoped idea without anything much as Jargon!.

After Playing around with a few VR SDKs before my recent relationship with Unity's UIT, I had one goal in mind - Build a prototype VR Project. Back then, I used VRTK to test the waters and now I use UIT rather comfortably for someone without previous experience with P_lugins and SDKs integration. My honest opinion is that I love UIT and wish more features can be added to it because it makes building so much easier.

It's fair to say that UIT hasn't reached the level of functionalities VRTK and other SDKs bring to the table but there's one important aspect VR Developers need; multi-platform development which it has great promise for. Less talk now, let's meet the features of my new best friend.

Interactors & Interactables: This Point doesn't need much explanation. It's well known that every VR World/experience must have basic interactors(In layman terms - XR Controllers) and Interactables (Objects you can Grab and Select). As for AR, this isn't a requirement because the physics associated with it often involves overlaying objects on surfaces without much need for interaction, which is not to say that in some cases interaction isn't used.
- Interactors - UIT achieves this Feature using the Cross-platform XR controller input Component. There are three main functions this provides (Object hover, select, and grab)
- Interactables - For an object to be an active Interactable, it must have a collection of scripts applied to it - the main being the XR Grab Interactable, XR Direct Interactable, XR Simple Interactable. These three are used differently and of the three, the first is most frequently used.
A VR Camera Rig: As Expected, when creating VR Experiences, the differentiating factor is a 360-degree world that can be viewed from different angles, as such, what makes this possible is a VR Camera Rig. UIT comes with an XR rig that can be configured for either room or stationary VR. There isn't much talk about this after it has been added to the scene, one important detail to know is that the XR controllers are usually children of this Prefab in the Hierarchy.

NOTE: Once the Sample UIT Package is Successfully set up - You have access to Most components directly from the GameObject Window.
Teleportation: With UIT, you can set up teleportation using the XR Controller. It Involves a fairly easy process of creating an area/plane and adding the Teloprataion Component to it. This allows the Player to hover over active fields and appear there instantaneously.
Visual Feedback/ Line rendering: perhaps one of the most exciting aspects of VR. Grabbing objects far away from the player and teleportation. The Line Renderer or Raycaster projects a Line (Color remains Unfixed) from your virtual controllers when you hover around Active fields - What I mean by this, Are you hovering over an Interactable or an area with teleportation set to active? If so, this Indicating Line is projected. By default, the Line Renderer is enabled to constantly project regardless if the state is set to active but this can be fixed with a little code.
Haptic Feedback: Since Haptics isn't a new term in the VR field, I would avoid divulging deeply into this. Customary, UIT has this feature that can be set up with the XR Controllers for giving a Haptics signals when Certain Events are Triggered in VR

Truly, there are always more features that I decide to not mention here, the above more-important ones are the core of UIT that must be understood while others can be picked up along the way. Dash it all! I have built a working VR Prototype Project with just the core features explained above 🥱. Oh, I promise, More good stuff to come.

Oculus XR Plugin for UIT

According to Statista, Oculus Rift and Quest hold the highest percentage of VR Games Published by Developers on a VR/AR Platform, this stands at 25% & 24% respectively with HTC Vive coming in at 20% rather fairly. If this doesn't ring a bell, Well, Nothing might for you. Because Oculus is the fastest-growing Platform both for Developers and Gamers. - For Devs, Revenue - For Gamers, Premium Entertainment (Absolutely Relative). As such, developers at Oculus were quick to get news about Unity's revised plan and created a plugin just for folks adopting the UIT package for VR Development. Today, You are gonna learn about this High-Budget Plugin.

If you want to create games for Oculus Standalone Headsets or Oculus Go and also plan to use the UIT package, one thing is constant - You need the Oculus XR Plugin. Much of what I talked about above applies to it as well, so you probably do get the hang of what it goes. So now, let's go right into how to install and configure it for the current starter scene in Unity (if you have it open, and not having ignored me this whole time). Follow the Ordered steps below, I won't write it twice:

With Unity Opened with the Starter Template on Scene view, you have almost all requirement ready save one
Go to Windows > Package Manager. In PM search for Oculus XR Plugin, Install and wait for it to Import
Now go to Edit > Project Settings > XR Plugin Management. inside this section, Check the box - Initialize XR on Startup and Oculus.
Further to this, by following this process you are enabling to build on a PC, MAC, or Linus machine. For Android build, switch the tab and enable Oculus there.

That's it! After you complete these steps, you can now "hopefully" run the Game view and experience the scene in VR. Indeed very easy, just my thought too.

The idea here is this, you can play or create any small scene with a few objects directly in Unity, Using the XR Interaction toolkit, by ensuring that a few certain prefabs are present in the Scene! What are they? Where can you find them in?. As we move into the next section we are gonna tackle these questions, that way I kill two birds with a stone. 😎

You now know how to set up UIT with your Oculus Headset but there's one more detail I need to observe - What if you have no Headsets and you just love VR?. I was once in that same position and I can tell you that it's not as impossible as everyone says it is - Developing without a Headset. Unity in part has made this possible with the Mock HMD XR Plugin.

Unity Mock HMD XR Plugin

In simple terms, the above reference means this - An Head Mounted Display that isn't a real version but mimics how the real version operates. Similar to the Oculus XR Plugin we looked at above, the Mock HMD Display allows you to move and interact in a virtual world without the need for a headset. It collects input actions from the plain old Keyboard, Gamepads, and other input devices. The Mock HMD functions in a similar way to how you'd expect the Oculus XR Plugin to; Basic interactions are mapped similarly with little changes in the input method. To set up a Mock HMD in your Project, follow the same steps that apply for the OCP by of course searching and installing from the package manager; Mock HMD XR. When Installed, don't expect it to work from the onset because there is a little more process involved.

You don't want to be stuck to the starter template without building from scratch. Like I mentioned earlier, some particular prefabs need hooking up together for UIT to be fully integrated into a project, take note of them because they are listed below. Access them by simply searching in the projects tab search;

XR Rig Demo [Prefab] - Necessary for your scene to be translated into VR 360 degree. It also houses the XR Virtual Controllers and other components that it requires e.g Ray Caster, Line Renderer, etc.
Input Action Manager [Prefab] - To manage Input Actions from the Keyboard, XR Controller, Gamepad. Etc. This way you can write functions such as - OnButtonDownPressed
Interaction Manager [Script] - Create an Empty game object and Add the Interaction Manager Script to it. This is for well, managing interactions.
XR Base Interactor [Script] - Should be added to any game object that you want to be interactable (grab, select, hover)
To get On Button Pressed Event, I might have to use or call the XR Device Simulator function.
For Use without a Headset, Install the XR Device Simulator from the package manager and add it to the Hierarchy. Some values, keypress mappings need to still be set up before use, watch the video below as this is complicated in itself.

And the list goes On as complexity increases. Now that you have a good solid understanding of the UIT package, focus for 5 minutes on the scene reading prefabs names and viewing their properties in the Hierarchy. It has been a very long Guide and as much as I have tried to make it all well if for instance you prefer or need further assistance through video, Splendid!, I have a video on just this topic.

Documentations about Unity XR Interaction Toolkit

For In-depth Jargonified analysis and docs, I have provided easy links below to some of the important points taught in this guide:

FEEDBACK

Consequently, after this long tutorial guide, naturally, you should run into a lot of errors, I should highly doubt if you tried this if you say u didn't. I expect your feedback on all these along with how impressive you thought this guide to be. Very commonly said but truly honest as well, 'It helps me prepare better informational guides'. I thank you very much for reading. If you please, watch my tutorial in the video about how to set-up the UIT specifically on a Gamepad.