An OpenXR Render Window for OGRE 3D

About

This has been tested working on Valve Index. This appears to be broken on Windows Mixed Reality due to the framebuffers being allocated in a different order.

This was made as part of a prototype development for a VR sculpting application based on an existing OGRE 3D app. It is an exploration, not a production-ready library.

I have implemented the plugin as a RenderWindow with some helper files that can be run inside Ogre's Direct3D11 RenderSystem. Some of the tasks should really belong to a RenderSystem, but extending a RenderSystem is a bigger job and keeping the new logic in one place makes it easier to understand what the work actually is.

As it stands, you can treat this as a starting point for implementing OpenXR in your project. Glastonbridge does not provide community support for this library.

Gotchas:

• assumes that Ogre and OpenXR are going to request the same Direct3D adapter
• doesn't report OpenXR lifecycle events back to Ogre
• requires a separate primary window
• it's a hack made to get results in a short timeframe

Installation

You will need the OGRE classic (i.e. not ogre-next) SDK, possibly the source code. You will also need the OpenXR loader, which I obtained from https://github.com/KhronosGroup/OpenXR-SDK

Because it is dependent on the D3D11RenderSystem, it needs to link against the lib for that RenderSystem (also the openxr_loader), which breaks the nice neat plugin framework that Ogre provides. Instead, you can use the source to build a DLL (see [[src/OgreOpenXRConfig.h]]) that links to it, so your project just needs to link against the DLL. This may have been overthinking it, IDK.

Usage

In your application's code, you create an OpenXR RenderWindow like so

#include "OgreOpenXRRenderWindow.h"

...

  xrRenderWindow = CreateOpenXRRenderWindow(root->getRenderSystem(), "VR Crafting");
  xrRenderWindow->create("VR Crafting", 0,0,true,nullptr);

Then you need to attach exactly two cameras to it (no surprises). These cameras will then be entirely controlled by the RenderWindow.

  Camera* leftEye = scnMgr->createCamera("leftEye");
  Camera* rightEye = scnMgr->createCamera("rightEye");

  xrRenderWindow->addViewport(leftEye,1 ,0,0,1,1);
  xrRenderWindow->addViewport(rightEye,0,0  ,0,1,1);

Credit and license

This project was written using the BasicXRApp sample provided by Microsoft as a reference, https://github.com/microsoft/OpenXR-MixedReality but it is its own work produced by Glastonbridge Software Limited. This code is provided under the MIT license.