swift - 使用 ARKit 将图库中的图像放置在墙上

Question

我有一个来自服务器并存储在图库中的图像列表。我想使用 ARKit 选择任何图像并将其放置在动态墙上，并希望将图像转换为 3d 图像 tp 执行缩放、移动图像等操作。

谁能指导我如何在 AR 中创建自定义对象？

Answer 1

要在 ARKit 中检测垂直表面(例如墙壁)，您需要首先设置 ARWorldTrackingConfiguration，然后在您的应用中启用 planeDetection。

因此，在您的类声明下，您将创建以下变量:

@IBOutlet var augmentedRealityView: ARSCNView!
let augmentedRealitySession = ARSession()
let configuration = ARWorldTrackingConfiguration()

然后初始化你的 ARSession 和 ViewDidLoad 例如:

override func viewDidLoad() {
    super.viewDidLoad()

    //1. Set Up Our ARSession
    augmentedRealityView.session = augmentedRealitySession

    //2. Assign The ARSCNViewDelegate
    augmentedRealityView.delegate = self

    //3. Set Up Plane Detection
    configuration.planeDetection = .vertical

    //4. Run Our Configuration
    augmentedRealitySession.run(configuration, options: [.resetTracking, .removeExistingAnchors])

}

现在您已全部设置为检测垂直平面，您需要连接到以下 ARSCNViewDelegate 方法:

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

这很简单:

Tells the delegate that a SceneKit node corresponding to a new AR anchor has been added to the scene.

在这个方法中，我们将明确地寻找任何已检测到的 ARPlaneAnchors，它为我们提供:

Information about the position and orientation of a real-world flat surface detected in a world-tracking AR session.

因此，将 SCNPlane 放置到检测到的垂直平面上非常简单:

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

extension ViewController: ARSCNViewDelegate{

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

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

        //2. Get The Size Of The ARPlaneAnchor
        let width = CGFloat(planeAnchor.extent.x)
        let height = CGFloat(planeAnchor.extent.z)

        //3. Create An SCNPlane Which Matches The Size Of The ARPlaneAnchor
        let imageHolder = SCNNode(geometry: SCNPlane(width: width, height: height))

        //4. Rotate It
        imageHolder.eulerAngles.x = -.pi/2

        //5. Set It's Colour To Red
        imageHolder.geometry?.firstMaterial?.diffuse.contents = UIColor.red

        //4. Add It To Our Node & Thus The Hiearchy
        node.addChildNode(imageHolder)

    }
}

将此应用到您的案例中:

在您的情况下，我们需要做一些额外的工作，因为您希望能够允许用户将图像应用于垂直平面。

因此，您最好的选择是让您刚刚添加的节点成为一个变量，例如

class ViewController: UIViewController {

    @IBOutlet var augmentedRealityView: ARSCNView!
    let augmentedRealitySession = ARSession()
    let configuration = ARWorldTrackingConfiguration()
    var nodeWeCanChange: SCNNode?

}

因此，您的Delegate Callback 可能如下所示:

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

extension ViewController: ARSCNViewDelegate{

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

        //1. If We Havent Create Our Interactive Node Then Proceed
        if nodeWeCanChange == nil{

            //a. Check We Have Detected An ARPlaneAnchor
            guard let planeAnchor = anchor as? ARPlaneAnchor else { return }

            //b. Get The Size Of The ARPlaneAnchor
            let width = CGFloat(planeAnchor.extent.x)
            let height = CGFloat(planeAnchor.extent.z)

            //c. Create An SCNPlane Which Matches The Size Of The ARPlaneAnchor
            nodeWeCanChange = SCNNode(geometry: SCNPlane(width: width, height: height))

            //d. Rotate It
            nodeWeCanChange?.eulerAngles.x = -.pi/2

            //e. Set It's Colour To Red
            nodeWeCanChange?.geometry?.firstMaterial?.diffuse.contents = UIColor.red

            //f. Add It To Our Node & Thus The Hiearchy
            node.addChildNode(nodeWeCanChange!)
        }


    }
}

现在您已经有了对 nodeWeCanChange 的引用，随时设置它的图像很简单!

每个 SCNGeometry 都有一组 Material ，它们是:

A set of shading attributes that define the appearance of a geometry's surface when rendered.

在我们的例子中，我们正在寻找 Material 漫反射属性，即:

An object that manages the material’s diffuse response to lighting.

然后是内容属性:

The visual contents of the material property—a color, image, or source of animated content.

显然你需要处理这一切的后勤工作，但是一个非常基本的例子可能看起来像假设你将图像存储到一个 UIImage 数组中，例如:

let imageGallery = [UIImage(named: "StackOverflow"), UIImage(named: "GitHub")]

我创建了一个 IBAction，它将根据按下的 UIButton 标签更改我们的 SCNNode's Geometry 的图像，例如:

/// Changes The Material Of Our SCNNode's Gemeotry To The Image Selected By The User
///
/// - Parameter sender: UIButton
@IBAction func changeNodesImage(_ sender: UIButton){

    guard let imageToApply = imageGallery[sender.tag], let node = nodeWeCanChange  else { return}
    node.geometry?.firstMaterial?.diffuse.contents = imageToApply

}

这足以为您指明正确的方向...希望对您有所帮助...