/// <summary>
/// Updates the VRPN tracker whenever it changes position
/// </summary>
/// <param name="sender"></param>
/// <param name="e"> Information about the object tracked</param>
private void PositionChanged(object sender, TrackerChangeEventArgs e)
{
//We convert movement to millimeters.
_position = new Microsoft.Xna.Framework.Vector3((float)e.Position.X, (float)e.Position.Y, (float)e.Position.Z);
_xpos = (float)e.Position.X;
_ypos = (float)e.Position.Y;
_zpos = (float)e.Position.Z;
// tools inverts e.Orientation.Z for packetizing/sending, so invert it back
_orientation = new Microsoft.Xna.Framework.Quaternion((float)e.Orientation.X, (float)e.Orientation.Y, (float)e.Orientation.Z, (float)e.Orientation.W);
Vector3Helper.QuaternionToEuler(e.Orientation.X, e.Orientation.Y, e.Orientation.Z, e.Orientation.W,
out _yaw, out _pitch, out _roll);
_pitch *= -1;
Matrix.CreateFromQuaternion(ref _orientation, out worldTransform);
worldTransform.Translation = _position;
}