Tracking a handheld accessory as a virtual sculpting tool

At a glance

Project structure

Source bundle/
└── SpatialSculpting/
    └── SpatialSculpting/
        ├── SpatialSculptingApp.swift
        ├── Compute/
        │   └── ComputeSystem.swift
        ├── ECS/
        │   └── SculptingToolComponent.swift
        ├── Document/
        │   └── VolumeDocument.swift
        ├── ContentView.swift
        ├── ViewModel/
        │   ├── HapticsModel.swift
        │   ├── SculptingToolModel.swift
        │   └── SculptingToolModel+GameController.swift
        ├── Mesh/
        │   ├── MarchingCubesMesh.swift
        │   ├── MarchingCubesParams.h
        │   └── MeshVertex.h
        └── Volume/
            └── VoxelVolume.swift

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: C/Objective-C header, Metal, Swift.
• The verified tree contains 4 project/configuration file(s) and 24 source declaration(s).

Overall architecture

flowchart LR
    N1["SpatialSculptingApp"]
    N2["ContentView"]
    N3["HapticsModel"]
    N4["ComputeDispatchSystem"]
    N5["RealityKit APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4
    N4 --> N5

Reference code

SpatialSculpting/SpatialSculpting/SpatialSculptingApp.swift:10 — architecture anchor

@main
struct SpatialSculptingApp: App {

    init() {
        ComputeDispatchSystem.registerSystem()
    }

    var body: some Scene {
        WindowGroup {
            ContentView().frame(width: 1500, height: 1500).frame(depth: 1500)
        }
        .windowStyle(.volumetric)
    }
}

Interpretation

The arrows summarize the source-visible entry, role-named types or folders, and framework direction; when nodes come from structural folders, the sequence is a high-level interpretation rather than proof that every adjacent node calls the next. Ownership is claimed only where the next section cites a stored property or assignment. The diagram is intentionally limited to the dominant path into RealityKit.

Ownership and state

classDiagram
    ComputeUpdateContext o-- SceneUpdateContext : sceneUpdateContext
    ComputeUpdateContext o-- MTLCommandBuffer : commandBuffer
    ComputeUpdateContext o-- MTLComputeCommandEncoder : _computeEncoder
    ComputeUpdateContext o-- MTLBlitCommandEncoder : _blitEncoder

Ownership evidence

SpatialSculpting/SpatialSculpting/Compute/ComputeSystem.swift:14 — stored dependency or nearest verified ownership anchor

struct ComputeUpdateContext {
    // ...
    let sceneUpdateContext: SceneUpdateContext
    // ...
}

Composition arrows indicate a source-visible construction expression or locally owned value state; aggregation means the owner stores or receives a dependency without proving exclusive lifetime ownership.

Concurrency, scheduling, and thread safety

Evidence limit: actor isolation, async/await, or Task creation does not by itself prove background-thread execution; Sendable conformance alone does not prove thread-safe mutation.

@MainActor/MainActor.run, DispatchQueue.main, and RunLoop.main are reported as distinct isolation, queue, and event-loop mechanisms. A plain Task is kept separate from Task.detached; neither is labeled as a background thread.

Reference code

SpatialSculpting/SpatialSculpting/Compute/ComputeSystem.swift:56 — representative execution boundary

protocol ComputeSystem {
    @MainActor
    func update(computeContext: inout ComputeUpdateContext)
}

State propagation, frameworks, and dependencies

Evidence limit: an import proves a source-level compilation dependency at the cited line; it does not prove runtime use, architectural adoption, or whether a Swift package is a direct application dependency.

receive(on:) describes downstream delivery scheduling, while subscribe(on:) describes upstream subscription/request/cancel scheduling. An import Combine alone establishes neither behavior nor a Store, reducer, Redux, or other application architecture.

Class and protocol design

SpatialSculpting/SpatialSculpting/Compute/ComputeSystem.swift:55 — representative type boundary

protocol ComputeSystem {
    @MainActor
    func update(computeContext: inout ComputeUpdateContext)
}

The source explicitly defines local protocol relationships: SculptingToolSystem → ComputeSystem.

Access control

Reference code

SpatialSculpting/SpatialSculpting/Compute/ComputeSystem.swift:49 — representative boundary

struct ComputeUpdateContext {
    // ...
    private var _computeEncoder: MTLComputeCommandEncoder? = nil
    // ...
}

Swift declarations without a modifier are internal; explicit private, fileprivate, private(set), public, or open entries above are interpreted by language semantics. Objective-C/C samples instead rely on header and implementation boundaries, which are not equivalent to Swift lexical privacy.

Logic ownership and placement

Design patterns

Naming conventions

• Types: App: SpatialSculptingApp; Component: ComputeSystemComponent, SculptingToolComponent; Document: VolumeDocument; Model: HapticsModel, SculptingToolModel; System: ComputeDispatchSystem, ComputeSystem, SculptingToolSystem; View: ContentView.
• Protocols: ComputeSystem.
• Methods: computeEncoder, blitEncoder, endEncoding, update, loadFromURL, fileWrapper, createMeshChunkEntity, sculptingVolume.
• Files: SpatialSculpting/SpatialSculpting/SpatialSculptingApp.swift, SpatialSculpting/SpatialSculpting/Compute/ComputeSystem.swift, SpatialSculpting/SpatialSculpting/ECS/SculptingToolComponent.swift, SpatialSculpting/SpatialSculpting/Document/VolumeDocument.swift, SpatialSculpting/SpatialSculpting/ContentView.swift, SpatialSculpting/SpatialSculpting/ViewModel/HapticsModel.swift.

Architecture takeaways

• SpatialSculptingApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches RealityKit, Metal, SwiftUI, ARKit through a deliberately small high-level chain; the detailed API graph remains inside the cited implementation files.
• Stored-property evidence identifies lifecycle collaboration; it does not by itself prove exclusive object ownership.
• Access-control conclusions separate verified language visibility from the likely design rationale.
• Local protocol relationships provide an explicit substitution boundary.

Source map

• Official Apple documentation