bool IsFaceTrackingAvailable(ref bool bNeedRestart);

    // initializes libraries and resources needed by the face tracking subsystem

    bool InitFaceTracking(bool bUseFaceModel, bool bDrawFaceRect);

    // releases the resources and libraries used by the face tracking subsystem

    void FinishFaceTracking();

    // this method gets invoked periodically to update the face tracking state

    // returns true if update is successful, false otherwise

    bool UpdateFaceTracking();

    // returns true if face tracking is initialized, false otherwise

    bool IsFaceTrackingActive();

    // returns true if face rectangle(s) must be drawn in color map, false otherwise

    bool IsDrawFaceRect();

    // returns true if the face of the specified user is being tracked at the moment, false otherwise

    bool IsFaceTracked(long userId);

    // gets the face rectangle in color coordinates. returns true on success, false otherwise

    bool GetFaceRect(long userId, ref Rect faceRect);

    // visualizes face tracker debug information

    void VisualizeFaceTrackerOnColorTex(Texture2D texColor);

    // gets the head position of the specified user. returns true on success, false otherwise

    bool GetHeadPosition(long userId, ref Vector3 headPos);

    // gets the head rotation of the specified user. returns true on success, false otherwise

    bool GetHeadRotation(long userId, ref Quaternion headRot);