使用 .obj 文件导出纹理

Question

我目前正在从事人脸跟踪和将人脸导出到 obj 文件中的项目。我成功导出它但无法导出纹理文件。我正在共享导出文件的代码，可能我遗漏了一些东西，请帮助我。当我调用函数newMesh!.generateLightMapTexture 时，它会导致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

下面我分享一下导出的代码：

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 {

    }
}

Answer 1

也许这就是您所需要的。尝试在崩溃之前添加此行。

newMesh!.addUnwrappedTextureCoordinates(forAttributeNamed: MDLVertexAttributeTextureCoordinate)