OpenXR Vulkan/OpenGL on Direct3D 12 interoperability layer

This software enables OpenXR apps developed for Vulkan/OpenGL to work with OpenXR runtimes that have support for Direct3D 12 and not Vulkan/OpenGL.

DISCLAIMER: This software is distributed as-is, without any warranties or conditions of any kind. Use at your own risks.

Setup

Download the latest version from the Releases page. Find the installer program under Assets, file OpenXR-Vk-D3D12.msi.

For troubleshooting, the log file can be found at %LocalAppData%\XR_APILAYER_MBUCCHIA_vulkan_d3d12_interop.log.

Limitations

This has only been tested with Windows Mixed Reality.
This has only been tested with NVIDIA and AMD video cards.
Vulkan support has been tested with BeamNG, the X-Plane 12 Demo, the HelloXR sample app from Khronos, Unity 2021, Godot 4, Adobe Substance 3D and Enscape 3D.
OpenGL support has been tested with HelloXR sample app from Khronos, Autodesk VRED 2024 and Paraview.
It is compatible with OpenXR Toolkit.

Known issues

Applications using legacy XR_KHR_vulkan_enable must enable Vulkan timeline semaphores at device creation time.

    VkPhysicalDeviceTimelineSemaphoreFeatures timelineSemaphoreFeatures{
        VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_TIMELINE_SEMAPHORE_FEATURES};
    timelineSemaphoreFeatures.timelineSemaphore = true;

    // Chain timelineSemaphoreFeatures to your VkDeviceCreateInfo struct.

Applications using OpenGL with an OpenXR runtimes without support for mutable FOV (as reported in XrViewConfigurationProperties) and applications using OpenGL and rendering quad layers will have rendering upside-down. The necessary code to Y-flip the image is not implemented.

If you are having issues, please visit the Issues page to look at existing support requests or to file a new one.

OpenXR Conformance

The API layer passed all OpenXR conformance tests (at v1.0.26.0) with Vulkan as the graphics API and with Windows Mixed Reality at the backing OpenXR runtime.

How does it work?

This API layer sits between any OpenXR application and the OpenXR runtime. It enhances the currently selected OpenXR runtime with the OpenXR extensions necessary for Vulkan support (XR_KHR_vulkan_enable and XR_KHR_vulkan_enable2). It uses the OpenXR runtime's Direct3D 12 support to efficiently bridge the application's Vulkan rendering to Direct3D 12. This processes does not add any overhead: the swapchains (drawing surfaces) requested by the application in Vulkan formats are imported as-is from Direct3D 12, there is no additional copy nor composition phase. Upon submission of the rendered frame, a simple fence synchronization primitive is inserted in the GPU queue shared with the OpenXR runtime, which will not block the application's rendering loop.