RealityKit -获取图元定位和相机之间的距离

import RealityKit
import ARKit

class ViewController: UIViewController, ARSessionDelegate {
    @IBOutlet var arView: ARView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        guard let scene = try? Entity.load(named: "Scene") else { return }
        arView.scene.anchors.append(scene)
        
        arView.session.delegate = self
        let configuration = ARWorldTrackingConfiguration()
        arView.session.run(configuration)
    }
    
    func session(_ session: ARSession, didUpdate frame: ARFrame) {
        guard let cameraEntity = arView.scene.anchors.first(where: { $0 is CameraEntity }) as? CameraEntity else { return }
        let entity = arView.scene.anchors.first(where: { $0 is Entity }) as! Entity
        
        let entityPosition = entity.worldTransform.columns.3.x
        let cameraPosition = cameraEntity.cameraTransform.columns.3.x
        
        let distance = abs(entityPosition - cameraPosition)
        print("Distance between entity and camera: \(distance)")
    }
}