OpenXR/OpenVR (virtual reality support)

[kwahoo]

This thread continues discussion from a thread about Oculus Rift.
I would like discuss here about wider VR hardware support. A few weeks ago an open VR/AR standard has been was presented: OpenXR.

Waiting for OpenXR hardware adoption (manufacturers like Oculus or Valve announced future support) I've started experimenting with another API: OpenVR.
OpenVR is not quite open as name suggest - it still needs a proprietary runtime (SteamVR), but unlike Oculus SDK it is supported on different operating systems and supports hardware from other manufacturers.

UPDATE OpenXR
The OpenXR support is almost done.

This is a pre-release introducing OpenXR support. Open View->FreeCAD-XR to view scene in virtual reality headset.

Requirements:
virtual reality headset
OpenXR runtime supporting OpenGL (XR_KHR_opengl_enable extension) eg. SteamVR, Monado
(optionally) motion controllers

Scene navigation using motion controllers:
analog stick/trackpad of the first controller moves viewer forward or backward along controller axis
analog stick/trackpad of the second controller rotates viewer around center of controller

Scene navigation using keyboard:

WSAD and Up/Down keys move in 3D space
Left/Right keys rotate
+/- keys scale scene

How to start:

Enable/run your OpenXR runtime (eg. by starting SteamVR) - make sure that OpenXR loader path is set up (Windows registry key "ActiveRuntime" in HKEY_LOCAL_MACHINE\SOFTWARE\Khronos\OpenXR\1, Linux: /etc/xdg/openxr/1/active_runtime.json)

Turn on motion controllers if you want use them

Run FreeCAD, open a 3D model

Start OpenXR session clicking View->FreeCAD-XR menu

You can download Windows build and Linux Appimage here.

The code can be found in this fork https://github.com/kwahoo2/FreeCAD

Notes about compilation:
0. Download and install OpenXR SDK from https://github.com/KhronosGroup/OpenXR-SDK (note: on Windows build the OpenXR Loader as a DLL)
1. Set BUILD_OPENXR to ON
2. Set BUILD_QT5 to ON

Outdated:

The Windows binary and Linux AppImage release can be downloaded here https://github.com/kwahoo2/FreeCAD/rele ... 19_preVR-1
Connect headset, run SteamVR and then start bin/FreeCAD.exe. Open a model and run View->FreeCAD OpenVR. A new, preview window should appear as soon as SteamVR detects active HMD.
Use analog stick or touchpad of first controller to translate world. Move stick forward - view will move where the controller is pointing. Use second controller to rotate world around two axes. Position of the controller sets center of rotation.

The implementation should work with all OpenVR compatible headsets, including Oculus Rift, HTC Vive, Valve Index and Windows Mixed Reality HMD's. Please report if this works (or not) for you.

phpBB [video]

I stopped working on the Python script and moved to C++. The code can be found in this fork https://github.com/kwahoo2/FreeCAD
Notes about compilation:
0. Download and install OpenVR SDK from https://github.com/ValveSoftware/openvr
1. Set BUILD_OPENVR to ON
2. Set BUILD_QT5 to ON
3. You may need to specify OpenVR_INCLUDE_DIR (/usr/local/include/openvr in my case)
4. You may need to specify OpenVR_LIBRARY (/usr/local/lib/libopenvr_api.a in my case)

Additional notes about compilation on Windows:
1. OpenVR_LIBRARY should point to lib/win64/openvr_api.lib distributed with the OpenVR SDK
2. openvr_api.dll can be found in openvr\bin\win64

End of update.

Known issues:
1. The code renders two exactly same pictures - wrong buffer configuration?
2. Head tracking is not implemented yet
3. SoFrustumCamera needs further investigation. I'm trying to get necessary variables for the camera from IVRSystem::GetProjectionMatrix and IVRSystem::GetEyeToHeadTransform matrices, but maybe there is a better way? Update: Use IVRSystem::GetProjectionRaw

Future work:
1. Fix issues
2. Remove SDL dependency, use QOpenGLWidget (?) Update: Check the new offscreen rendering driver in SDL https://hg.libsdl.org/SDL/rev/9692ad570003
3. Port to C++ Initial OpenVR C++ port https://github.com/kwahoo2/FreeCAD/comm ... b8ab0c1e28
4. Add basic navigation
5. Add controllers support (for navigation) Initial work done
6. Improve rendering quality (antialiasing etc.) and performance - Initial work done
7. Move to OpenXR - initial OpenXR support done https://forum.freecadweb.org/viewtopic. ... 03#p379203


Initially, I started tinkering with jriegel Rift's implementation, but later i found Python bindings for OpenVR pyopenvr. Basic idea is: write (and experiment with) an implementation in pyopenvr, and then port the code to C++.

Here is the repository: https://github.com/kwahoo2/freecad-pyopenvr
Steps to run the code:
1. Install pyopenvr, and SDL + OpenGL Python packages
2. Run SteamVR
3. Paste the code into FreeCAD

[Kunda1]

Steps to run the code:
1. Install pyopenvr, and sdl + opengl python packages
2. Run SteamVR
3. Paste the code into FreeCAD

Known issues:
1. The code renders two exactly same pictures - wrong buffer configuration?
2. Head tracking is not implemented yet
3. SoFrustumCamera needs further investigation. I'm trying to get necessary variables for the camera from IVRSystem::GetProjectionMatrix and IVRSystem::GetEyeToHeadTransform matrices, but maybe there is a better way?

Future work:
1. Fix issues
2. Remove SDL dependency, use QOpenGLWidget (?)
3. Port to C++
4. Add basic navigation
5. Add controllers support (for navigation)
6. Move to OpenXR

@kwahoo
Fantastic!
Lets put this on Github or Gitlab, so people can pull and test quickly and contribute code more easily. You can also create a Roadmap etc...

[kwahoo]

Lets put this on Github or Gitlab, so people can pull and test quickly and contribute code more easily.

Done. I updated the original post.

At this moment mostly(at least I hope so...) correct rendering with rotation and position tracking is possible.

I found the culprit of rendering the same image twice:
creating two scenes this way:

Code: Select all

rootScene = [SoSeparator()] * 2
...
for eye in range(2):
  m_sceneManager.setSceneGraph(rootScene[eye])

does not work. The second scene changes the first one.

[schurik]

This sounds great.
Is it possible to run my Rift S on CATIA with this?

[kwahoo]

Is it possible to run my Rift S on CATIA with this?

Rift S: Yes.
Catia: No, at least not with this script.

----
I have some issues to be ironed out, there is probably an error in cameras configuration (objects are too big, moving too fast). Update: this needs more testing, added a simple test file to the repository: a room with pillars and a table.

But meanwhile some performance teaser (click to see a bigger pic):


To be honest, I was expecting worse fps;)

[Kunda1]

Sent another PR to soup up the README.

[kwahoo]

Thanks!

There is one thing, that worries me - SoSceneManager::render is pretty slow with huge models. In the worst scenario I got ~13 fps and ~30% GPU utilisation. Using SoRenderManager (since event handling is not very important for VR) instead does not change much. Low fps and big latency (especially latency) makes this a very uncomfortable experience.

Maybe I can use SoGLRenderAction, and instead using Open Inventor camera, use pure OpenGL projection and model matrices, similar as shown here in the part Applying a Render Action Inside a GLX Window And then instead of traversing full scenegraph I could just manipulate matrices.

[Kunda1]

There is one thing, that worries me - SoSceneManager::render is pretty slow with huge models. In the worst scenario I got ~13 fps and ~30% GPU utilisation. Using SoRenderManager (since event handling is not very important for VR) instead does not change much. Low fps and big latency (especially latency) makes this a very uncomfortable experience.

Maybe I can use SoGLRenderAction, and instead using Open Inventor camera, use pure OpenGL projection and model matrices, similar as shown here in the part Applying a Render Action Inside a GLX Window And then instead of traversing full scenegraph I could just manipulate matrices.

I would pose this as a question on the Open Issues subforum so it gets more exposure.

[kwahoo]

I ported a basic OpenVR support to C++. It has the same functionality as the Python script.

The implementation can be found in this repository https://github.com/kwahoo2/FreeCAD Commit introducing OpenVR https://github.com/kwahoo2/FreeCAD/comm ... b8ab0c1e28

Notes about compilation:
1. Set BUILD_OPENVR to ON
2. Set BUILD_QT5 to ON
3. You may need to specify OpenVR_INCLUDE_DIR (/usr/local/include/openvr in my case)
4. You may need to specify OpenVR_LIBRARY (/usr/local/lib/libopenvr_api.a in my case)

There is no OS-specific code in the implementation - it should run both on Linux and Windows. Mac has some beta SteamVR support, but I do not have any experience with it .

Running a scene:
1. Start SteamVR
2. Open a model in the FreeCAD
3. Run View->FreeCAD-OpenVR

[kwahoo]

Another update:
Added some navigation using controllers - see video in the first post:
stick/trackpad of the first controller controls world translation, the second one controls rotation.

Dear VR users, please let me know if you need precompiled packages for testing. If not, the first post contains some building from source tips.