我目前正在开发一项关于人脸跟踪并将人脸导出为obj文件的项目。我已经成功地将其导出，但无法导出纹理文件。我分享了导出文件的代码，可能我漏掉了什么，请帮助我。每当我调用函数newMesh!.generateLightMapTexture时，它会使代码崩溃并给出以下日志：
Removed 41721 bad triangles
Can't choose for edge creation
Can't choose for edge creation
Can't choose for edge creation
Can't choose for edge creation
Can't choose for edge creation
Can't choose for edge creation
Can't choose for edge creation
Can't choose for edge creation ...
libc++abi.dylib: terminating with uncaught exception of type std::out_of_range: unordered_map::at: key not found
以下是导出代码：
func exportFile() {
let geometry = currentFaceAnchor.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 material = MDLMaterial(name: "mat1", scatteringFunction: MDLPhysicallyPlausibleScatteringFunction())
material.setProperty(MDLMaterialProperty.init(name: "matName", semantic: MDLMaterialSemantic.ambientOcclusion))
let submesh = MDLSubmesh(indexBuffer: triangleIndices, indexCount: geometry.triangleIndices.count, indexType: .uInt16, geometryType: .triangles, material: material)
let vertexDescriptor = MDLVertexDescriptor()
// Attributes
vertexDescriptor.attributes[0] = MDLVertexAttribute(name: MDLVertexAttributePosition,
format: .float3,
offset: 0,
bufferIndex: 0)
vertexDescriptor.attributes[1] = MDLVertexAttribute(name: MDLVertexAttributeTextureCoordinate,
format: .float2,
offset: 0,
bufferIndex: 1)
// Layouts
vertexDescriptor.layouts[0] = MDLVertexBufferLayout(stride: MemoryLayout<SIMD3<Float>>.stride)
vertexDescriptor.layouts[1] = MDLVertexBufferLayout(stride: MemoryLayout<SIMD2<Float>>.stride)
let mdlMesh = MDLMesh(vertexBuffers: [vertices, textureCoordinates], vertexCount: geometry.vertices.count, descriptor: vertexDescriptor, submeshes: [submesh])
let newMesh = MDLMesh.newSubdividedMesh(mdlMesh, submeshIndex: 0, subdivisionLevels: 2)
let light = MDLLight.init(scnNode: node)
light.lightType = .ambient
newMesh!.generateLightMapVertexColorsWithLights(toConsider: [light], objectsToConsider: [newMesh!], vertexAttributeNamed: MDLVertexAttributeNormal)
**//Crashing Next Line**
newMesh!.generateLightMapTexture(withQuality: 1.0, lightsToConsider: [light], objectsToConsider: [newMesh!], vertexAttributeNamed: MDLVertexAttributeNormal, materialPropertyNamed: "matName")
let asset = MDLAsset(bufferAllocator: allocator)
asset.add(newMesh!)
let fileManager = FileManager.default
let documentsPath = fileManager.urls(for: .documentDirectory, in: .userDomainMask).first!
let exportUrl = documentsPath.appendingPathComponent("face.obj")
do {
try asset.export(to: exportUrl)
let fileURLs = try fileManager.contentsOfDirectory(at: documentsPath, includingPropertiesForKeys: nil)
DispatchQueue.main.async {
let activityVC = UIActivityViewController(activityItems: fileURLs, applicationActivities: nil)
self.present(activityVC, animated: true, completion: nil)
}
}
catch {
}
}