ARFaceTrackingConfig点击测试

很明显，基于World Tracking配置用于检测平面的ARKit光线投射方法不适用于Face Tracking场景。在您的情况下，您需要使用SceneKit的hit-testing。对于hit-testing，您将无法使用estimatedPlane，你需要一个canonical face mask。当使用前置摄像头时，你对XZ坐标的理解是完全正确的-XZ平面是镜像的。另外值得注意的是，相机的IR TrueDepth传感器在10到100 cm的距离下“工作”。ARFaceAnchor仅在此范围内生成。
在iPad Pro上的Swift Playgrounds应用中运行此代码。

import ARKit
import SceneKit
import PlaygroundSupport

class ViewController : UIViewController {
    var sceneView = ARSCNView(frame: .zero)
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.view = self.sceneView
        sceneView.delegate = self
        sceneView.scene = SCNScene()
        
        let config = ARFaceTrackingConfiguration()
        config.maximumNumberOfTrackedFaces = 1
        sceneView.session.run(config)
    }
}

extension ViewController {       
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        let location: CGPoint? = touches.first?.location(in: sceneView)
                                            
        var hitTestOptions = [SCNHitTestOption: Any]()
        hitTestOptions[.boundingBoxOnly] = true
                                            
        let hitTestResults: [SCNHitTestResult] = sceneView.hitTest(location!, 
                                                   options: hitTestOptions)
                    
        guard let hit = hitTestResults.first else { return }
                                        
        let sphere = SCNNode(geometry: SCNSphere(radius: 0.005))
        sphere.simdPosition = hit.simdWorldCoordinates
        sceneView.scene.rootNode.addChildNode(sphere)            
    }
}

extension ViewController : ARSCNViewDelegate {
    func renderer(_ renderer: SCNSceneRenderer, nodeFor anchor: ARAnchor) -> SCNNode? {
        let faceGeo = ARSCNFaceGeometry(device: sceneView.device!)
        let node = SCNNode(geometry: faceGeo)
        node.geometry?.firstMaterial?.lightingModel = .physicallyBased
        node.geometry?.firstMaterial?.diffuse.contents = UIColor.green
        return node
    }
    func renderer(_ renderer: SCNSceneRenderer, didUpdate node: SCNNode,
                                                    for anchor: ARAnchor) {    
        if let faceAnchor = anchor as? ARFaceAnchor,
           let faceGeo = node.geometry as? ARSCNFaceGeometry {
            faceGeo.update(from: faceAnchor.geometry)
        }
    }
}

PlaygroundPage.current.needsIndefiniteExecution = true
PlaygroundPage.current.liveView = ViewController()