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class GameViewController: UIViewController, SCNSceneRendererDelegate {

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override func viewDidLoad() {
    super.viewDidLoad()
    
    let scene = SCNScene(named: "art.scnassets/ship.scn")!
    scnView.delegate = self
    scnView.scene = scene

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private var pipelineState: MTLRenderPipelineState!
private var vertexBuffer: MTLBuffer!

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func setupMetalResources() {
    guard let device = scnView.device else {
        assertionFailure()
        return
    }
    
    // We're drawing a simple triangle so we only need a position and a color
    struct TriangleVertex {
        var position: vector_float4
        var color: vector_float4

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override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    setupMetalResources()
}

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#include <metal_stdlib>
using namespace metal;

// Define the Vertex data structure. This corresponds to the TriangleVertex struct
// that was defined in Swift
struct Vertex
{
    float4 position [[position]];
    float4 color;
};

MasDennis

func renderer(_ renderer: SCNSceneRenderer, didRenderScene scene: SCNScene, atTime time: TimeInterval) {
    // Used to encode additional rendering commands after SceneKit has drawn its content.
    guard let encoder = scnView.currentRenderCommandEncoder else { return }
    
    encoder.setRenderPipelineState(pipelineState)
    encoder.setVertexBuffer(vertexBuffer, offset: 0, index: 0)
    encoder.drawPrimitives(type: .triangle, vertexStart: 0, vertexCount: 3)
}

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import UIKit
import ARKit

class ViewController: UIViewController, ARSCNViewDelegate {

    @IBOutlet var sceneView: ARSCNView!
    
    private var viewportSize: CGSize!
    
    override var shouldAutorotate: Bool { return false }

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func renderer(_ renderer: SCNSceneRenderer, willRenderScene scene: SCNScene, atTime time: TimeInterval) {
    // Get the capture image (which is a cvPixelBuffer) from the current ARFrame
    guard let capturedImage = sceneView.session.currentFrame?.capturedImage else { return }
    
    let imageRequestHandler = VNImageRequestHandler(cvPixelBuffer: capturedImage, 
                                                    orientation: .leftMirrored, 
                                                    options: [:])
    
    do {
        try imageRequestHandler.perform([objectDetectionRequest])

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lazy var objectDetectionRequest: VNCoreMLRequest = {
    do {
        let model = try VNCoreMLModel(for: YOLOv3TinyInt8LUT().model)
        let request = VNCoreMLRequest(model: model) { [weak self] request, error in
            self?.processDetections(for: request, error: error)
        }
        return request
    } catch {
        fatalError("Failed to load Vision ML model.")
    }