如何在 AR 中检测多个图像？

Question

我正在使用 ARKit 创建这个实时报纸应用程序，它将报纸上的图像转换为视频。我能够检测到一个图像并在其上播放视频，但是当我尝试在两个图像上执行此操作并在该图像上播放相应的视频时我收到一个错误 Attempted to add a SKNode which already has a parent

我尝试检查跟踪的图像并将它们与参考图像进行比较，但我认为我的逻辑有问题。

这是我的ViewDidAppear() 方法

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    // Create a session configuration
    let configuration = ARImageTrackingConfiguration()

    if  let trackedImages = ARReferenceImage.referenceImages(inGroupNamed: "NewsPaperImages", bundle: Bundle.main) {

        configuration.trackingImages = trackedImages
        configuration.maximumNumberOfTrackedImages = 20



    }

    // Run the view's session
    sceneView.session.run(configuration)
}

func renderer(_ renderer: SCNSceneRenderer, nodeFor anchor: ARAnchor) -> SCNNode? {
    let node = SCNNode()

    if let imageAnchor = anchor as? ARImageAnchor {

        if(imageAnchor.referenceImage == UIImage(named: "Image2_River")) {
            self.videoNode = SKVideoNode(fileNamed: "riverBeauty.mp4")
        }

        print("Yes it is an image")
        self.videoNode.play()

        let videoScene = SKScene(size: CGSize(width: 480, height: 360))

        videoNode.position = CGPoint(x: videoScene.size.width/2, y: videoScene.size.height/2)
        videoNode.yScale = -1.0
        videoScene.addChild(videoNode)

        let plane = SCNPlane(width: imageAnchor.referenceImage.physicalSize.width, height: imageAnchor.referenceImage.physicalSize.height)


        plane.firstMaterial?.diffuse.contents = videoScene

        let planeNode = SCNNode(geometry: plane)
        planeNode.eulerAngles.x = -.pi/2

        node.addChildNode(planeNode)

        }
    return node

}

它应该在每个检测到的图像上播放视频，但它却崩溃了。

Answer 1

查看您的代码，根据您所说的，我认为您需要更改逻辑，以使用 ARReferenceImage 的 name 属性创建视频节点。

当您静态（在ARResourceBundle 内）或动态创建ARReferenceImage 时，您可以为其指定一个名称，例如：

然后，您可以使用名称添加逻辑，为检测到的每个 referenceImage 分配不同的视频。

为了保留您的代码DRY，您可以创建一个可重用的函数来创建您的视频节点。

这样一个简单的例子可能看起来像这样：

  //-------------------------
  //MARK: - ARSCNViewDelegate
  //-------------------------

  extension ViewController: ARSCNViewDelegate{

    func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {

      //1. Check We Have Detected An ARImageAnchor
      guard let validAnchor = anchor as? ARImageAnchor else { return }

      //2. Create A Video Player Node For Each Detected Target
      node.addChildNode(createdVideoPlayerNodeFor(validAnchor.referenceImage))

    }


    /// Creates An SCNNode With An AVPlayer Rendered Onto An SCNPlane
    ///
    /// - Parameter target: ARReferenceImage
    /// - Returns: SCNNode
    func createdVideoPlayerNodeFor(_ target: ARReferenceImage) -> SCNNode{

      //1. Create An SCNNode To Hold Our VideoPlayer
      let videoPlayerNode = SCNNode()

      //2. Create An SCNPlane & An AVPlayer
      let videoPlayerGeometry = SCNPlane(width: target.physicalSize.width, height: target.physicalSize.height)
      var videoPlayer = AVPlayer()

      //3. If We Have A Valid Name & A Valid Video URL The Instanciate The AVPlayer
      if let targetName = target.name,
        let validURL = Bundle.main.url(forResource: targetName, withExtension: "mp4", subdirectory: "/art.scnassets") {
        videoPlayer = AVPlayer(url: validURL)
        videoPlayer.play()
      }

      //4. Assign The AVPlayer & The Geometry To The Video Player
      videoPlayerGeometry.firstMaterial?.diffuse.contents = videoPlayer
      videoPlayerNode.geometry = videoPlayerGeometry

      //5. Rotate It
      videoPlayerNode.eulerAngles.x = -.pi / 2

      return videoPlayerNode

    }

  }

如您所见，我选择使用AVPlayer 作为我的视频内容，但如果您愿意，您可以继续使用您的 videoScene。

希望它为您指明正确的方向...