Trackfwd - A command line application to broadcast OpenVR tracking data over OSC

/tɹækfɔɹwəɹd/

This is a simple rust command line application that broadcasts OpenVR tracking data over OSC. I was frustrated with the LiveLinkXR plugin in Unreal Engine, so rather than relying on it, I decided to write my own solution. This will only broadcast generic trackers (vive trackers, tundra trackers, etc) and not controllers/HMD, although it should be trivial to modify the code to include them.

Usage

trackfwd <port>

For a detailed guide, see the application specific tutorials:

• Unreal Engine
• Unity

Arguments

• <port>: The port to broadcast the OSC messages on.
• --target <target>: The IP address of the OSC target. Default is 127.0.0.1.
• --coords <coords>: The coordinate system to use. Options are open-vr, blender, unity and unreal. Default is open-vr.
• --help: Print help information.

Coordinate Systems

Different applications use different coordinate systems. The --coords flag allows you to specify which coordinate system to use.

• open-vr: The default coordinate system used by OpenVR. It uses a right-handed coordinate system with the y-axis pointing up. 1 unit is equal to 1 meter.
• blender: The coordinate system used by Blender. It uses a right-handed coordinate system with the z-axis pointing up. 1 unit is equal to 1 meter.
• unity: The coordinate system used by Unity. It uses a left-handed coordinate system with the y-axis pointing up. 1 unit is equal to 1 meter.
• unreal: The coordinate system used by Unreal Engine. It uses a left-handed coordinate system with the z-axis pointing up. 1 unit is equal to 1 centimeter.

In the future, it may be useful to add a custom coordinate system option. For now, if you need a different unit scale than the ones provided, you can either modify the code or scale the values in the receiving application.

OSC Message Format

The OSC message format is as follows:

/tracker/<index> <x> <y> <z> <qx> <qy> <qz> <qw>

<index> is the device index of the tracker. <x>, <y>, and <z> are the position of the tracker in meters. <qx>, <qy>, <qz>, and <qw> are the quaternion rotation of the tracker.

Building

To build the application, you will need to have Rust installed. You can install Rust by following the instructions on the official website. Once you have Rust installed, you can build the application by running the following command:

cargo build --release

The compiled binary will be located in the target/release directory.

What's Next?

There's a few features that could be added to this application to make it more useful:

• Adding support for VRChat's OSC standard
• Customizing the OSC message format
• Support for controllers and HMDs
• Adding arguments to choose the coordinate system and unit scale independently
• Making a simple GUI for configuration
• Recording and exporting tracking data
• Playback of recorded tracking data
• Making a LiveLink plugin for Unreal Engine to integrate with existing workflows