swift - 如何在 SwiftUI 中清除 SceneView 3D 对象的背景

Question

有谁知道如何清除 SceneView 3D 对象的背景？我正在尝试使用 UIColor.clear，但它使它变成白色。[ ]

import SwiftUI
import SceneKit

struct TestView: View {
    var body: some View {
    
        ZStack{
                    Color.green
                    SceneView(
                        scene: {
                            let scene = SCNScene(named: "Earth.scn")!
                            scene.background.contents = UIColor.clear
                            return scene
                        }(),
                        options: [.autoenablesDefaultLighting,.allowsCameraControl]
                    )
                    .frame(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height/2, alignment: .center)
                
                }
    }
}

struct TestView_Previews: PreviewProvider {
    static var previews: some View {
        TestView()
    }
}