ARKit Stereo – Is it possible to run two ARSCNView at the same time?

Question

I was thinking to do some modification to my existing AR app, and I wanted to split the view and add inside 2 ARSCNView in this way users can use the VR Card Box and have a different experience but Xcode is always returning me:

Session (0x102617d10): did fail with error: Error Domain=com.apple.arkit.error Code=102 "Required sensor failed."

So, I'm supposing that I can't run 2 ARSCNView sessions at the same time, or am I wrong?

Answer 1

No, or at least it’s possible that you will get errors all the time. It seems that when you use both an ARSCN and a ARSKVIEW View at the same time, a sensor error is presented. It may be due to privacy?

Answer 2

The answer is: Yes, it's possible.

Use the following code to accomplish it:

import UIKit
import SceneKit
import ARKit

class ViewController: UIViewController, ARSCNViewDelegate {

    @IBOutlet weak var sceneView: ARSCNView!
    @IBOutlet weak var sceneView2: ARSCNView!

    override func viewDidLoad() {
        super.viewDidLoad()

        sceneView.delegate = self
        sceneView.showsStatistics = true
        let scene = SCNScene(named: "art.scnassets/ship.scn")!
        sceneView.scene = scene
        sceneView.isPlaying = true

        // Setup for sceneView2
        sceneView2.scene = scene
        sceneView2.showsStatistics = sceneView.showsStatistics

        // Now sceneView2 starts receiving updates
        sceneView2.isPlaying = true     
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        let configuration = ARWorldTrackingConfiguration()
        sceneView.session.run(configuration)
    }
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        sceneView.session.pause()
    }
    func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
        DispatchQueue.main.async {
            self.updateFrame()
        }
    }
    func updateFrame() {   
        // Clone pointOfView for Second View
        let pointOfView: SCNNode = (sceneView.pointOfView?.clone())!

        // Determine Adjusted Position for Right Eye
        let orientation: SCNQuaternion = pointOfView.orientation
        let orientationQuaternion: GLKQuaternion = GLKQuaternionMake(orientation.x, 
                                                                     orientation.y, 
                                                                     orientation.z, 
                                                                     orientation.w)
        let eyePos: GLKVector3 = GLKVector3Make(1.0, 0.0, 0.0)
        let rotatedEyePos: GLKVector3 = GLKQuaternionRotateVector3(orientationQuaternion, 
                                                                   eyePos)
        let rotatedEyePosSCNV: SCNVector3 = SCNVector3Make(rotatedEyePos.x, 
                                                           rotatedEyePos.y, 
                                                           rotatedEyePos.z)  
        let mag: Float = 0.064 // Interocular distance (in metres)
        pointOfView.position.x += rotatedEyePosSCNV.x * mag
        pointOfView.position.y += rotatedEyePosSCNV.y * mag
        pointOfView.position.z += rotatedEyePosSCNV.z * mag

        // Set PointOfView for SecondView
        sceneView2.pointOfView = pointOfView    
    }
}

For more details look at this project on a GitHub.