visionOS ModelSortGroupComponent Playground

visionOSModelSorting.swift

import SwiftUI
import RealityKit

struct ImmersiveView: View {
    var body: some View {
        RealityView { content in
            // .postPass was the only one that had any visible effect for me
            let sortGroup = ModelSortGroup(depthPass: .postPass)
            
            // this represents some UI and should always be drawn in front of everything else
            let planeContainerEntity = Entity()
            let plane = ModelEntity(
                mesh: .generatePlane(width: 1, height: 1, cornerRadius: 0.1),
                materials: [SimpleMaterial(color: .green, isMetallic: true)]
            )
            planeContainerEntity.addChild(plane)
            planeContainerEntity.position = [0.5, 1.5, -1.5]
            planeContainerEntity.visit { entity in
                entity.components.set(ModelSortGroupComponent(group: sortGroup, order: 1))
            }
            content.add(planeContainerEntity)
            
            // this represents models in my scene and should be drawn as usual but still respect the UI (e.g appear behind it)
            let boxContainerEntity = Entity()
            let box = ModelEntity(
                mesh: .generateBox(size: 0.5, cornerRadius: 0.05),
                materials: [
                    SimpleMaterial(color: .red, isMetallic: true)
//                    OcclusionMaterial()
                ]
            )
            boxContainerEntity.addChild(box)
            boxContainerEntity.position = [0.05, 1.5, -1.5]
            boxContainerEntity.visit { entity in
                entity.components.set(ModelSortGroupComponent(group: sortGroup, order: 0))
            }
            content.add(boxContainerEntity)
            
            let sphereContainerEntity = Entity()
            let sphere = ModelEntity(
                mesh: .generateSphere(radius: 0.4),
                materials: [
                    SimpleMaterial(color: .blue, isMetallic: true)
//                    OcclusionMaterial()
                ]
            )
            sphereContainerEntity.addChild(sphere)
            sphereContainerEntity.position = [0.1, 1.45, -2]
            sphereContainerEntity.visit { entity in
                entity.components.set(ModelSortGroupComponent(group: sortGroup, order: 0))
            }
            content.add(sphereContainerEntity)
        }
    }
}

extension Entity {
    func visit(using block: (Entity) -> Void) {
        block(self)
        for child in children {
            child.visit(using: block)
        }
    }
}