IVRSystem::ResetSeatedZeroPose

void ResetSeatedZeroPose()

Sets the zero pose for the seated tracker coordinate system to the current position and yaw of the HMD. After ResetSeatedZeroPose all GetDeviceToAbsoluteTrackingPose calls that pass TrackingUniverseSeated as the origin will be relative to this new zero pose. The new zero coordinate system will not change the fact that the Y axis is up in the real world, so the next pose returned from GetDeviceToAbsoluteTrackingPose after a call to ResetSeatedZeroPose may not be exactly an identity matrix.