Swift 如何使用遮罩对象使对象的背面不可见？

我想在投影时隐藏对象的背面。你看，物体在墙上加深了。我可以制作某种遮罩对象使其不可见吗

import UIKit
import RealityKit

class ViewController: UIViewController {

    @IBOutlet var arView: ARView!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Load the "Box" scene from the "Experience" Reality File
        let ARscene1 = try! Experience.load_1()
        let ARscene2 = try! Experience.load_2()
        let ARscene3 = try! Experience.load_3() //that scene, object named "mask"          

        // Add the box anchor to the scene
        arView.scene.anchors.append(ARscene1)
        arView.scene.anchors.append(ARscene2)
        arView.scene.anchors.append(ARscene3)
    }
}

---

在这里您可以看到如何操作。

这里有一个小macOS项目，向您展示如何在RealityKit中设置

遮挡材质：

import Cocoa
import RealityKit

class GameViewController: NSViewController {

    @IBOutlet var arView: ARView!
    let anchor = try! TwoCubes.loadTwoObjects()

    override func awakeFromNib() {
        arView.environment.background = .color(.black)

        let boxEntity1: Entity = anchor.invisible!.children[0]
        var boxComponent1: ModelComponent = boxEntity1.components[ModelComponent]!.self

        let boxEntity2: Entity = anchor.visible!.children[0]
        var boxComponent2: ModelComponent = boxEntity2.components[ModelComponent]!.self

        let material1 = OcclusionMaterial()  // Material hiding other objects behind it
        var material2 = SimpleMaterial()
        material2.baseColor = .color(.orange)

        boxComponent1.materials = [material1]
        boxComponent2.materials = [material2]

        anchor.invisible!.components.set(boxComponent1)
        anchor.visible!.components.set(boxComponent2)

        arView.scene.anchors.append(anchor)
    }
}

这里有一个小macOS项目，向您展示如何在RealityKit中设置
遮挡材质
：

import Cocoa
import RealityKit

class GameViewController: NSViewController {

    @IBOutlet var arView: ARView!
    let anchor = try! TwoCubes.loadTwoObjects()

    override func awakeFromNib() {
        arView.environment.background = .color(.black)

        let boxEntity1: Entity = anchor.invisible!.children[0]
        var boxComponent1: ModelComponent = boxEntity1.components[ModelComponent]!.self

        let boxEntity2: Entity = anchor.visible!.children[0]
        var boxComponent2: ModelComponent = boxEntity2.components[ModelComponent]!.self

        let material1 = OcclusionMaterial()  // Material hiding other objects behind it
        var material2 = SimpleMaterial()
        material2.baseColor = .color(.orange)

        boxComponent1.materials = [material1]
        boxComponent2.materials = [material2]

        anchor.invisible!.components.set(boxComponent1)
        anchor.visible!.components.set(boxComponent2)

        arView.scene.anchors.append(anchor)
    }
}