Obscuring virtual items in a scene behind real-world items

At a glance

Project structure

Source bundle/
└── Occlusion/
    ├── App/
    │   └── EntryPoint.swift  # EntryPoint
    ├── Generators/
    │   └── MeshAnchorGenerator.swift  # MeshAnchorGenerator
    ├── Views/
    │   ├── MainView.swift  # MainView
    │   └── WorldOcclusionView.swift  # WorldOcclusionView
    └── Extensions/
        └── SIMD3.swift

Structure observations

• The runtime boundary is WindowGroup + ImmersiveSpace; the pruned tree lists only files that explain lifecycle, state, or framework integration.
• App code is compact; any explicit model, provider, or entity owner is still shown below rather than collapsed into view-local state.

Overall architecture

flowchart LR
    EntryPoint_1["EntryPoint"]
    WindowGroup___ImmersiveSpace_2["WindowGroup + ImmersiveSpace"]
    MainView_3["MainView"]
    MeshAnchorGenerator_4["MeshAnchorGenerator"]
    RealityView_entity_graph_5["RealityView entity graph"]
    ARKit_providers___RealityKit_6["ARKit providers + RealityKit"]
    EntryPoint_1 --> WindowGroup___ImmersiveSpace_2
    WindowGroup___ImmersiveSpace_2 --> MainView_3
    MainView_3 --> MeshAnchorGenerator_4
    MeshAnchorGenerator_4 --> RealityView_entity_graph_5
    RealityView_entity_graph_5 --> ARKit_providers___RealityKit_6

Reference code

Occlusion/App/EntryPoint.swift:11 — the app or executable entry declares the outer scene lifecycle.

struct EntryPoint: App {
    // ...
}

The diagram is a responsibility flow, not a claim that every adjacent node directly calls the next. It keeps scene ownership, shared state, RealityKit content, and framework-provider work at separate levels.

Ownership and state

classDiagram
    MeshAnchorGenerator --> Entity : root

Ownership evidence

Occlusion/Generators/MeshAnchorGenerator.swift:16 — representative stored state or the nearest verified lifecycle anchor.

    var root: Entity?

    /// The collection that comprises the `MeshAnchor.id` and the entity associated with the anchors.
    private var anchors: [UUID: Entity] = [:]

    init(root: Entity) {
        self.root = root
    }

Ownership here is deliberately narrow: @Environment and weak references are shared links, initialized @State or stored services are lifecycle ownership, and a RealityView content closure owns additions to its entity graph without making the SwiftUI view a reference-type owner.

Class and protocol design

The source defines no local substitution protocol in the reviewed boundary. Its protocol use is framework-facing (App, View, RealityKit/ARKit protocols, or platform adapters), so this document does not label the whole app protocol-oriented.

Access control

No reviewed declaration uses fileprivate, private(set), public, open; unmodified Swift declarations are internal.

Reference code

Occlusion/Generators/MeshAnchorGenerator.swift:19 — representative visibility boundary.

    private var anchors: [UUID: Entity] = [:]

    init(root: Entity) {
        self.root = root
    }

Logic ownership and placement

Design patterns

Naming conventions

• Role suffixes are evidence, not decoration: View: MainView, WorldOcclusionView.
• Protocols: no app-defined protocol in the reviewed source.
• Commands use verb-led methods: run, runSession.
• Files generally match their primary type; Views, Models, Managers, Providers, Components, Systems, and Packages folders describe architectural roles where present.

Architecture takeaways

• Treat EntryPoint as the owner of scene declarations, not as the owner of every RealityKit entity created later.
• Keep view-local interaction in SwiftUI, but move provider sessions, playback resources, shared game state, or transport state into a stable owner when their lifetime exceeds one render pass.
• Run ARKit providers for the scene lifetime and consume their asynchronous updates in cancellable tasks; map anchors to entities at the boundary.
• Model immersive-space open, transition, and close states explicitly so windows and immersive content cannot drift apart.
• The compact source does not justify adding repository, coordinator, or protocol layers beyond the model, provider, or view boundary the sample actually declares.

Source map

• Official Apple documentation