使用ARKit检测人脸移动方向（上，左，下，右）

Question

我正在研究ARFaceTrackingConfiguration以检测人脸，并且使用Vision框架可以轻松实现。现在，我要检测用户是否正在查看“左-右-上-底”，并根据此信息在屏幕上显示一些内容。但是问题是我无法检测到该怎么做！

到目前为止我尝试过什么？

extension FaceDetectionViewController: ARSCNViewDelegate {
    //implement ARSCNViewDelegate functions for things like error tracking
    func renderer(_ renderer: SCNSceneRenderer, didUpdate node: SCNNode, for anchor: ARAnchor) {
        scanForFaces()
        if let faceAnchor = anchor as? ARFaceAnchor {
            DispatchQueue.main.async {
                //This changes as I move camera and cannot able to detect logic
                let position = faceAnchor.transform.position()
                self.lblX.text = "X: \(node.position.x)----Y: \(node.position.y)"
                self.lblY.text = "X: \(position.x)----Y: \(position.y)"
            }
        }
        //Same this problem appears here too
        DispatchQueue.main.async {
            self.lblX.text = " \(node.eulerAngles.x) "
            self.lblY.text = " \(node.eulerAngles.y) "
        }
    }
}

extension matrix_float4x4 {
    func position() -> SCNVector3 {
        return SCNVector3(columns.3.x, columns.3.y, columns.3.z)
    }
}

@objc
private func doFaceScan() {

    //get the captured image of the ARSession's current frame
    guard let capturedImage = sceneView.session.currentFrame?.capturedImage else { return }
    let image = CIImage.init(cvPixelBuffer: capturedImage)

    let detectFaceRequest = VNDetectFaceRectanglesRequest { (request, error) in

        DispatchQueue.main.async {
            //Loop through the resulting faces and add a red UIView on top of them.
            if let faces = request.results as? [VNFaceObservation] {
                for face in faces {
                    self.faceFrame(from: face.boundingBox)
                }
            }
        }
    }

    try? VNImageRequestHandler(ciImage: image, orientation: self.imageOrientation).perform([detectFaceRequest])
}

有人可以帮忙吗？