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We have a reasonably complex mesh and need to update the vertex positions for every frame using custom code running on the CPU. It seems like SceneKit is not really set up to make this easy, as the SCNGeometry is immutable. What is the easiest (yet performant) way to achieve this? So far I can see two possible approaches: 1) Create a new SCNGeometry for every frame. I suspect that this will be prohibitively expensive, but maybe not? 2) It seems that SCNProgram and its handleBinding... method would allow updating the vertex positions. But does using SCNProgram mean that we have to write all our own shaders from scratch? Or can we still use the default Scenekit vertex and fragment shaders even when using SCNProgram?

I am trying to use the new LiDAR scanner on the iPhone 12 Pro in order to gather points clouds which later on will be used as input data for neural networks. Since I am relatively new to the field of computer vision and augmented reality, I started by looking at the official code examples (e.g., Visualizing a Point Cloud Using Scene Depth - https://developer.apple.com/documentation/arkit/environmental_analysis/visualizing_a_point_cloud_using_scene_depth) and the documentation of ARKit, SceneKit, Metal and so. However, I still do not understand how to get the LiDAR data. I found another thread in this forum (Exporting Point Cloud as 3D PLY Model - https://developer.apple.com/forums/thread/658109) and the given solution works so far. However, I do not understand that code in detail, unfortunately. So I am not sure if this gives me really the raw LiDAR data or if some (internal) fusion with other (camera) data is happening, since I could not figure out where the data comes from exactly in the example. Could you please give me some tips or code examples on how to work with/access the LiDAR data? It would be very much appreciated!

I have an MTKView in which I want to first render a SceneKit scene onto a Render Texture and then pass this render texture into my own post-processing stage. It works fine, I see my Scene rendered correctly with all the objects, but there are no shadows being renderered and I've worked out that it's the SCNRenderer call that's not drawing them (the scene in a SCNView, ARSCNView etc. will show shadows fine). i.e., the nodes are casting correctly, and the light is set to cast shadows, so it's not a scene issue. Presumably I've not set up the descriptor with extra details that it needs for shadow rendering, but I'm not certain what the SCNRenderer is actually needing here? Sadly the documentation isn't revealing a great to deal to me on this subject. Any pointers would be much appreciated, no matter how general. I can't even find examples of the SCNRenderer being used in similar situations. let descriptor = MTLRenderPassDescriptor() descriptor.colorAttachments[0].loadAction = .clear descriptor.colorAttachments[0].clearColor = MTLClearColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 1.0) descriptor.colorAttachments[0].texture = metalRenderTexture descriptor.colorAttachments[0].storeAction = .store if let commandBuffer = commandQueue.makeCommandBuffer() { commandBuffer.label = "3DSceneBuffer" if isDrawingPreVizScene { sceneKitRenderer.render(withViewport: CGRect(x: 0, y: 0, width: metalRenderTexture!.width, height: metalRenderTexture!.height), commandBuffer: commandBuffer, passDescriptor: descriptor) } commandBuffer.commit() }

I am porting a functioning Swift App to SwiftUI with the ambitious intention of Multiple platform coding, so the project was created as such. I've worked out every issue except as the title suggests. My pertinent code: import SwiftUI import SceneKit struct ContentView: View { var scene : SCNScene = SCNScene = { () -> SCNScene in          //  DO NOT REPLACE OR MODIFY THE FIRST AND LAST LINES OF THIS VAR DECLARATION, e.g., "var scene:SCNScene{ ... }"  else initScene(newScene) FAILS to create children! let newScene = SCNScene() initScene(newScene)                            //  adds ChildNodes named: "precession" & "nuclearSpin" let newCamera = SCNNode() newCamera.position = SCNVector3(x: 0, y: 0 ,z: 40) newCamera.name = "cameraNode" newCamera.camera = SCNCamera() newScene.rootNode.addChildNode(newCamera) 10. newScene.fogDensityExponent = 0.0 return newScene }() @EnvironmentObject var structures:Structures @State private var Ncv = Int() @State private var indexMomentcv = Int() var body: some View { ZStack{ 20. SceneView( 21. scene: scene, 22. pointOfView: scene.rootNode.childNode(withName: "cameraNode", recursively: false), 23. options: [.allowsCameraControl, .autoenablesDefaultLighting, .temporalAntialiasingEnabled] 24. ).colorInvert() 25.             VStack(alignment: .trailing){ 26.                 Group{ 27.                     HStack{ 28.                         VStack{ // ... and so on 29. I have verified the existence of all nodes created for the scene, i.e., the objects to be seen, using these useful functions: func printChildNodeHierarchy(node: SCNNode) { node.enumerateChildNodes( { (anyNode,false) -> Void in return print( anyNode ) } ) }  //  SUPER handy func printChildNodeTransform(node: SCNNode) { node.enumerateChildNodes( { (anyNode,false) -> Void in return print( anyNode.name!,"\t", anyNode.simdTransform,"\t",anyNode.scale ) } ) } func printChildNodeAction   (node: SCNNode) { node.enumerateChildNodes( { (anyNode,false) -> Void in return print( anyNode.name!,"\t", anyNode.hasActions,"\t",anyNode.actionKeys ) } ) } ...which print in the debugging area. I have verified the materials assignments to the elements of those nodes. So, everything is in place as in the functioning Swift/macOS App but I just don't see the objects. What I've tried: Since I run in DarkMode theme I have cycled through the combinations of Dark/Light and with/without line 24's .colorInvert() and swapping ZStack with HStack. Some combo's do wash-out, but still no objects. I zero'd out the fog thinking it might be too foggy. Not. I've created a scene.scn file as a resource, applied the above attributes to it, reference it with scene = SCNScene(named: scene.scn"), but get the same non-result. Idk if some checkbox is errant in the build/target etc. area. Wouldn't know if it was. I'm not a professional programmer. Any thoughts are appreciated. I've been stuck for days. oh yeah: as of this posting I am up to date on all Apple software, running 2018 MacMini/Intel/SSD

It is unclear to me how the whole thing has to be implemented in SwiftUI. Currently: After an input (for example moving the camera) the renderer function is called correctly. Goal: The renderer function should also be called without needing input. Setup: struct ContentView: View {   @ObservedObject var gameData : GameViewModel       var body: some View {     SceneView(       scene: gameData.scene,       pointOfView: gameData.camera,       options: [         .allowsCameraControl       ],       delegate: gameData     )   } } class GameViewModel: NSObject, ObservableObject { ... } extension GameViewModel: SCNSceneRendererDelegate {   func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) { ... } }