How to present a metal frame

To present a Metal frame in visionOS, you can follow the steps outlined in the session "Render Metal with passthrough in visionOS" and "Bring your iOS or iPadOS game to visionOS" from WWDC 2024.

1. Create a Rendering Session:

   • Use compositor services to create a rendering session.
   • Utilize Metal APIs to render your frames.
   • Integrate ARKit for world and hand tracking.

   For more details, you can refer to the session Render Metal with passthrough in visionOS.

2. Render to a Texture:

   • You can start with a CAMetalLayer for simplicity, but moving to a low-level texture API will give you more control.
   • Create a view that contains the CAMetalLayer and use a CADisplayLink to get a callback every frame.

   Here's a code snippet for rendering to a CAMetalLayer:

   class MetalView: UIView {
       override class var layerClass: AnyClass {
           return CAMetalLayer.self
       }
   
       var metalLayer: CAMetalLayer {
           return layer as! CAMetalLayer
       }
   
       private var displayLink: CADisplayLink?
   
       override init(frame: CGRect) {
           super.init(frame: frame)
           setupDisplayLink()
       }
   
       required init?(coder: NSCoder) {
           super.init(coder: coder)
           setupDisplayLink()
       }
   
       private func setupDisplayLink() {
           displayLink = CADisplayLink(target: self, selector: #selector(render))
           displayLink?.add(to: .main, forMode: .default)
       }
   
       @objc private func render() {
           // Render to the metalLayer here
       }
   }
   

   For more details, you can refer to the session Bring your iOS or iPadOS game to visionOS.

3. Enhance the Rendering:

   • Add stereoscopy to add depth to your game.
   • Implement head tracking to make your game look like a physical window into another world.
   • Add Variable Refresh Rate (VRR) to improve performance.

   For more details, you can refer to the session Bring your iOS or iPadOS game to visionOS.

By following these steps, you can effectively present a Metal frame in visionOS, enhancing the immersive experience of your application.