The latest version of Unreal Engine 4, version 4.27, brings “production-ready” support for OpenXR. The change comes just in time for Oculus developers, as the company recently announced it’s fully moving open to the OpenXR standard for VR development going forward.

You may recall news back in May that the early access version of Unreal Engine 5 includes improved support for OpenXR. And while developers can play with that version of the engine and its XR tools, the engine’s creator (Epic Games), doesn’t recommend the early access version of Unreal Engine 5 for anything more than experiments at this point. For developers building anything they intend to ship to the public, the company is still recommends Unreal Engine 4.

Since Unreal Engine 5 itself isn’t ready for prime time, Epic Games is continuing to update the production-ready Unreal Engine 4. The latest of which, version 4.27, is the first that the company says includes production-ready OpenXR capabilities.

OpenXR is a royalty-free standard that aims to standardize the development of VR and AR applications, making hardware and software more interoperable. The standard has been in development since April 2017 and is backed by virtually every major hardware, platform, and engine company in the VR industry, including key AR players.

OpenXR has seen a slow but steady adoption since reaching version ‘1.0’ in 2019, and in the last 12 months it has significantly picked up pace with SteamVR officially supported it back in February and Oculus announcing last month that it’s going “all in” on the standard, saying that all new developer features will be built on top of OpenXR going forward.

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That makes Unreal Engine 4.27 a timely release; when Oculus said it would be fully shifting to OpenXR development last month, it put XR developers in an odd spot because the two biggest game engines, Unity and Unreal Engine, didn’t yet claim to offer production-ready OpenXR support.

Unity developers will have to wait a while longer before they can confidently make the leap to OpenXR as oculus expects that the Unity OpenXR plugin won’t be “fully supported” until early 2022. That will be a bigger deal once it finally happens because Unity is far and away more used than Unreal Engine when it comes to building XR content.

But maybe developers should take another look… last we checked, Oculus still has a special deal for developers building VR apps with Unreal Engine; the company offers to cover engine royalties for a game’s first $5 million in revenue.

Epic says that the OpenXR support in Unreal Engine 4.27 supports extension plugins from the Unreal Marketplace, which means that developers can add extra OpenXR functionality through plugins rather than waiting for updates to the entire engine.

New VR and AR Development Templates

Unreal Engine 4.27 also adds an improved VR Template which Epic says is “designed to be a starting point for all your VR projects,” and comes with basic VR capabilities built-in, like teleport locomotion, snap rotation, object grabbing, a spectator camera, and a VR-capable menu system.

The VR Template offers support for Oculus Quest 1 & 2, Quest with Oculus Link, Rift S, Valve Index, HTC Vive, and Windows Mixed Reality. Thanks to OpenXR, Epic says that “the template’s logic works on multiple platforms and devices without any platform-specific checks or calls.”

For PC VR, Unreal Engine 4.27 also includes experimental support for fixed foveated rendering, a technique which reduces the quality of peripheral imagery in favor of higher quality at the center where the user can see most sharply through the lens. Fixed foveated rendering in Unreal Engine 4.27 is currently limited to Windows platforms with DX12 and a GPU supporting VRS Tier 2.

Unreal Engine 4.27 also includes a new template for handheld AR development which is designed as a starting point for developers building AR apps based on ARCore (Android) and ARKit (iOS). Similar to the VR template, the AR Template includes basics like a built-in UI, a tool for users to take snapshots of the AR content, and the ability to move, rotate, and scale models places into the world.

The new engine update further includes heaps of improvements to Unreal Engine’s virtual production tools which are designed to combine real-time CGI environments with live-action filmmaking. Check out the complete patch notes for Unreal Engine 4.27 here if you want to go in-depth.

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  • kontis

    It looks like Khronos canceled half of OpenXR.

    Originally the idea was to have 2 universal layers:
    1. device layer
    2. app layer

    Now there is only the app layer in OpenXR and the slides don’t show the device layer anymore.

    Because of to that Oculus can be fully OpenXR compliant while not letting any non-Oculus headset to use Oculus Store (not like it matters anymore).
    But this also means that SteamVR’s openness to any hardware cannot be easily recreated with OpenXR alone.
    It looks like every hardware vendor will still need a runtime to handle the connection with the device, so I guess Steam will continue to provide that with their OpenVR.

    • Christian Schildwaechter

      The device layer wasn’t canceled, it is optional/postponed and referred to in the 1.0 specs:

      1.1. What is OpenXR?

      […] Optionally, a runtime may support device layer plugins which allow access to a variety of hardware across a commonly defined interface.

      The 2017 slides explaining the idea behind OpenXR showed both layers, and when the preliminary 0.9 spec was released in 2019, it was still in the diagram, but with an added disclaimer

      * OpenXR 1.0 is focused on enabling cross-platform applications. Optional device plugin interface will be supported post V1.0

      The 0.9 spec already contained the “optional” clause mentioned above. My guess is they removed it from the diagrams when the spec was finalized because people would expect it to be already available.

      The app layer/application interface is the more important one, as it allows developers to easily address multiple platforms with a single source base. This way a game created for the Oculus Quest using OpenXR can easily be ported to the HTC Focus 3 or Pico 3, which are based on the same hardware, but also for any PCVR HMD, a future x86 based Valve mobile headset or an Apple XR device, even if you cannot take the Oculus binary and run it on a Pico 3 or a PC.

      The device layer was always to be used after the company specific runtime, e.g. from Oculus, had already processed the image including distortion correction and corrections like ASW, followed by the optional “OpenXR Device Plugin Extension” talking to “Device Vendor-Supplied Device Driver”. This probably never meant that there would be basically a hardware abstraction layer like a Java virtual machine (with all its performance problems), it looks more like a way for a vendor to create compatible drivers. This way e.g. a Quest Pro 5 would be able to run a binary for the Quest 2 even if the way the driver talks to the hardware has changed in a significant way since the app was released.

      I doubt that vendor lock in had anything to do with postponing the device layer, the added complexity is the more likely cause. And even a fully universal device layer wouldn’t guarantee portability, e.g. DRM on Steam still binds you to the store and prevents you from running the binary on another PC, even though it is fully compatible and all the APIs are the same.

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  • A piece of good news for us developers, even if I’m more interested in the Unity plugin…

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  • Rogue Transfer

    A correction: The company is Facebook Technologies – the company Oculus was legally dissolved back in 2018, when the CEO left and the teams were restructured into Facebook’s existing AR/VR division.

  • VRFriend

    Epic games has VR development deep in in their as*es. HP Reverb G2, so top VR goggles do not work with Unreal Engine since 10 months. Controllers inaccessible in their Editor. Not visible.Not working. Nothing works, no support from Epic Games. Just desperate users on forum trying to help each other without success. Stop promoting this stupid a*s company.

    • Andrew Jakobs

      But, is that a problem created by Epic or is it HP that doesn’t provide support. If the G2 doesn’t work, there might also be a problem with other MR based headsets.
      And to be honest, the in-editor VR part has been flaky for a while for all devices. As long as the headsets work ingame. I do agree in-editor should also get some more loving. But your comment on not ‘promoting’ the unreal engine is just stupid as openxr support is far from shitty and UE is an excellent engine. Unity for instance also has it’s own flaws just like any other engine has it’s flaws so does UE.

    • David Wilhelm

      To make the G2 controller enumerations appear, the G2 plugin MUST be enabled. What I want to know is whether they’ll manage to make the Oculus Touch controllers themselves even point in the same direction under XR — they currently don’t and require the developer to alter the rotations or provide user adjustment controls.

      Try full G2 support in the next XR build of Bombyx! Combo builds support Oculus+SteamVR. Featuring multiple game modes such as Gravatar, Zero-G, and MonkeyMode, with artwork and character designs from Katsumi Yokota (Rez) and Mike DuBois (Grateful Dead, Pink Floyd). visit Bombyx.gg or find it on Sidequest. :)