ios - 从 URL Xcode 快速加载 3d 资源

Question

我有一个简单的 HTTP 服务器在运行，我试图从我的本地服务器获取这个 scenekit，但它显示 NIL 错误，或错误加载场景。我不明白如何从我简单的本地主机加载这个模型。如何配置我的代码，以便我能够从远程或本地服务器获取任何 Scenekit。

提前致谢

  do {
                let shipScene = try SCNScene(url: URL(fileURLWithPath: "http://localhost:8080/chair.scn") , options: nil)



            // Set the scene to the view
            sceneView.scene = shipScene
            let shipNode = shipScene.rootNode.childNodes.first!
            shipNode.position = SCNVector3Zero
            shipNode.position.z = 0.15
            shipNode.position.y = 0
            shipNode.position.x = 0
            let action = SCNAction.repeatForever(SCNAction.rotate(by: .pi, around: SCNVector3(0, 1, 0), duration: 5))
            shipNode.runAction(action)
            planeNode.addChildNode(shipNode)
            node.addChildNode(planeNode)

        } catch {
            print("ERROR loading scene")
        }

Answer 1

正如@Prashant 所说，您需要先实际下载模型才能使用它。

因此，您需要做的第一件事是创建一个 URLSession 来下载文件，例如:

/// Downloads An SCNFile From A Remote URL
func downloadSceneTask(){

        //1. Get The URL Of The SCN File
        guard let url = URL(string: "http://localhost:8080/chair.scn") else { return }

        //2. Create The Download Session
        let downloadSession = URLSession(configuration: URLSession.shared.configuration, delegate: self, delegateQueue: nil)

        //3. Create The Download Task & Run It
        let downloadTask = downloadSession.downloadTask(with: url)
        downloadTask.resume()      
    }

 }

然后我们将引用 URLSessionDownloadDelegate 例如:

class ViewController: UIViewController, URLSessionDownloadDelegate { }

现在我们已经连接了委托(delegate)，我们需要使用以下回调将我们下载的文件复制到设备的Documents Directory:

func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {

    //1. Create The Filename
    let fileURL = getDocumentsDirectory().appendingPathComponent("chair.scn")

    //2. Copy It To The Documents Directory
    do {
        try FileManager.default.copyItem(at: location, to: fileURL)

        print("Successfuly Saved File \(fileURL)")

        //3. Load The Model
        loadModel()

    } catch {

        print("Error Saving: \(error)")
    }

}

请注意，在该函数中，我使用以下辅助方法来获取文档目录:

/// Returns The Documents Directory
///
/// - Returns: URL
func getDocumentsDirectory() -> URL {

let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
let documentsDirectory = paths[0]
return documentsDirectory

}

下载并复制文件后，我们将调用 loadModel 函数 (3)，如下所示:

/// Loads The SCNFile From The Documents Directory
func loadModel(){

    //1. Get The Path Of The Downloaded File
    let downloadedScenePath = getDocumentsDirectory().appendingPathComponent("chair.scn")

    do {

        //2. Load The Scene Remembering The Init Takes ONLY A Local URL
        let modelScene =  try SCNScene(url: downloadedScenePath, options: nil)

        //3. Create A Node To Hold All The Content
        let modelHolderNode = SCNNode()

        //4. Get All The Nodes From The SCNFile
        let nodeArray = modelScene.rootNode.childNodes

        //5. Add Them To The Holder Node
        for childNode in nodeArray {
            modelHolderNode.addChildNode(childNode as SCNNode)
        }

        //6. Set The Position
        modelHolderNode.position = SCNVector3(0, 0, -1.5)

        //7. Add It To The Scene
        self.augmentedRealityView?.scene.rootNode.addChildNode(modelHolderNode)


    } catch  {
        print("Error Loading Scene")
    }

}

希望对你有帮助