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In an iOS ARKit app, I've been trying to save the ARFaceGeometry data to an OBJ file. I followed the explanation here: How to make a 3D model from AVDepthData?. However, the OBJ isn't created correctly. Here's what I have: func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) { guard let faceAnchor = anchor as? ARFaceAnchor else { return } currentFaceAnchor = faceAnchor // If this is the first time with this anchor, get the controller to create content. // Otherwise (switching content), will change content when setting `selectedVirtualContent`. if node.childNodes.isEmpty, let contentNode = selectedContentController.renderer(renderer, nodeFor: faceAnchor) { node.addChildNode(contentNode) } // https://stackoverflow.com/questions/52953590/how-to-make-a-3d-model-from-avdepthdata let geometry = faceAnchor.geometry let allocator = MDLMeshBufferDataAllocator() let vertices = allocator.newBuffer(with: Data(fromArray: geometry.vertices), type: .vertex) let textureCoordinates = allocator.newBuffer(with: Data(fromArray: geometry.textureCoordinates), type: .vertex) let triangleIndices = allocator.newBuffer(with: Data(fromArray: geometry.triangleIndices), type: .index) let submesh = MDLSubmesh(indexBuffer: triangleIndices, indexCount: geometry.triangleIndices.count, indexType: .uInt16, geometryType: .triangles, material: MDLMaterial(name: "mat1", scatteringFunction: MDLPhysicallyPlausibleScatteringFunction())) let vertexDescriptor = MDLVertexDescriptor() // Attributes vertexDescriptor.addOrReplaceAttribute(MDLVertexAttribute(name: MDLVertexAttributePosition, format: .float3, offset: 0, bufferIndex: 0)) vertexDescriptor.addOrReplaceAttribute(MDLVertexAttribute(name: MDLVertexAttributeNormal, format: .float3, offset: MemoryLayout.stride, bufferIndex: 0)) vertexDescriptor.addOrReplaceAttribute(MDLVertexAttribute(name: MDLVertexAttributeTextureCoordinate, format: .float2, offset: MemoryLayout.stride + MemoryLayout.stride, bufferIndex: 0)) // Layouts vertexDescriptor.layouts.add(MDLVertexBufferLayout(stride: MemoryLayout.stride + MemoryLayout.stride + MemoryLayout.stride)) let mdlMesh = MDLMesh(vertexBuffers: [vertices, textureCoordinates], vertexCount: geometry.vertices.count, de}scriptor: vertexDescriptor, submeshes: [submesh]) mdlMesh.addNormals(withAttributeNamed: MDLVertexAttributeNormal, creaseThreshold: 0.5) let asset = MDLAsset(bufferAllocator: allocator) asset.add(mdlMesh) let documentsPath = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first! let exportUrl = documentsPath.appendingPathComponent("face.obj") try! asset.export(to: exportUrl)The resulting OBJ file looks like this. I would expect many more vertices, and the index values look wrong.# Apple ModelIO OBJ File: facemtllib face.mtlg v -0.000128156 -0.0277879 0.0575149vn 0 0 0vt -9.36008e-05 -0.0242016usemtl material_1f 1/1/1 1/1/1 1/1/1f 1/1/1 1/1/1 1/1/1f 1/1/1 1/1/1 1/1/1... and many more lines