检查trackingImage在相机框架中是否完全可见

Question

我正在开发一个ARKit ImageTracking应用，出于我们的AR体验，我们希望Tracking image应该完全可见。如果部分可见，我需要显示一个UI消息“请确保Marker完全可见”。 所以我添加了一个平面作为SCNNode，它等于标记的大小。如下 并获得了边界框或平面的四个角，但是如何检测此平面是完全可见的，还是平面的所有四个角都在相机框架中？

func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
    //1. If Out Target Image Has Been Detected Than Get The Corresponding Anchor
    guard let currentImageAnchor = anchor as? ARImageAnchor else { return }

    let x = currentImageAnchor.transform
    print(x.columns.3.x, x.columns.3.y , x.columns.3.z)

    //2. Get The Targets Name
    let name = currentImageAnchor.referenceImage.name!

    //3. Get The Targets Width & Height In Meters
    let width = currentImageAnchor.referenceImage.physicalSize.width
    let height = currentImageAnchor.referenceImage.physicalSize.height

    //4. Create A Plane Geometry To Cover The ARImageAnchor
    let planeNode = SCNNode()
    planeNode.name = "markerSizePlane"
    let planeGeometry = SCNPlane(width: width, height: height)
    planeGeometry.firstMaterial?.diffuse.contents = UIColor.blue
    planeNode.opacity = 0.25
    planeNode.geometry = planeGeometry


    //5. Rotate The PlaneNode To Horizontal
    planeNode.eulerAngles.x = -.pi/2

    //The Node Is Centered In The Anchor (0,0,0)
    node.addChildNode(planeNode)
}

/* Getting corners of plane */
func renderer(_ renderer: SCNSceneRenderer, willRenderScene scene: SCNScene, atTime time: TimeInterval) {
    var bottomLeft: SCNVector3!
    var topRight: SCNVector3!
    var topLeft: SCNVector3!
    var bottomRight: SCNVector3!

    //1. Get The Current Point Of View
    guard let pointOfView = sceneView.pointOfView else { return }

    scene.rootNode.enumerateChildNodes(){
        node, stop in
            if node.name == "markerSizePlane"{
                //print("markerSizePlane position \(node.position)")
                let (min, max) = node.boundingBox
                bottomLeft = SCNVector3(min.x, min.y, 0)
                topRight = SCNVector3(max.x, max.y, 0)
                topLeft = SCNVector3(min.x, max.y, 0)
                bottomRight = SCNVector3(max.x, min.y, 0)

            }
    }
}