Implementing playing card overlap and physical characteristics

At a glance

Project structure

Source bundle/
└── Project/
    ├── MessyPileExample/
    │   ├── MessyPileExampleApp.swift
    │   ├── Views/
    │   │   └── PlaygroundView.swift
    │   ├── Support/
    │   │   ├── CenterOfMassSolver.swift
    │   │   └── ConvexBoundary2D.swift
    │   ├── Entity/
    │   │   └── Playground.swift
    │   ├── Equipment/
    │   │   ├── Card.swift
    │   │   ├── MessyPile.swift
    │   │   ├── Seat.swift
    │   │   ├── Stack.swift
    │   │   └── Table.swift
    │   └── Interaction/
    │       └── Interaction.swift
    └── Packages/
        └── RealityKitContent/
            └── Sources/
                └── RealityKitContent/
                    └── RealityKitContent.swift

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: Swift.
• The verified tree contains 4 project/configuration file(s) and 16 source declaration(s).

Overall architecture

flowchart LR
    N1["MessyPileExampleApp"]
    N2["PlaygroundView"]
    N3["TabletopKit APIs"]
    N1 --> N2
    N2 --> N3

Reference code

Project/MessyPileExample/MessyPileExampleApp.swift:12 — architecture anchor

@main
struct MessyPileExampleApp: App {
    @State var playground = Playground()
    var body: some SwiftUI.Scene {
        WindowGroup {
            PlaygroundView()
                .environment(playground)
        }
        .windowStyle(.volumetric)
        .defaultSize(width: 1, height: 1, depth: 1, in: .meters)
    }
}

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 TabletopKit.

Ownership and state

classDiagram
    MessyPileExampleApp *-- Playground : playground
    PlaygroundView o-- Entity : volumetricRoot
    OrientedBox o-- Pose2D : pose
    OrientedBox o-- Rect3DFloat : boundingBox

Ownership evidence

Project/MessyPileExample/MessyPileExampleApp.swift:14 — stored dependency or nearest verified ownership anchor

@main
struct MessyPileExampleApp: App {
    @State var playground = Playground()
    // ...
}

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

Project/MessyPileExample/Entity/Playground.swift:19 — representative execution boundary

    @MainActor
    init() {
        let table = Table()
        // ...
    }

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

Project/MessyPileExample/MessyPileExampleApp.swift:13 — representative type boundary

@main
struct MessyPileExampleApp: App {
    @State var playground = Playground()
    // ...
}

No local protocol conformance is claimed as protocol-oriented design; external framework conformances are listed only as dependencies.

Access control

Reference code

Project/MessyPileExample/Support/BoundedConvexHull.swift:116 — representative boundary

    internal func findEdgeIndexSurrounding(corners: [Point3DFloat],
                                           center: Point3DFloat,
                                           from vertex: Point3DFloat) -> Int {
        let vertexToCenter = center - vertex
        // ...
    }

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: MessyPileExampleApp; View: PlaygroundView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: calculateCenterOfMass, clampCenterOfMass, calculateCenterOfContactAndWeight, calculateCentersOfMass, distance, contains, strictlyContains, height.
• Files: Project/MessyPileExample/MessyPileExampleApp.swift, Project/MessyPileExample/Views/PlaygroundView.swift, Project/MessyPileExample/Support/CenterOfMassSolver.swift, Project/MessyPileExample/Support/ConvexBoundary2D.swift, Project/MessyPileExample/Entity/Playground.swift, Project/MessyPileExample/Equipment/Card.swift.

Architecture takeaways

• MessyPileExampleApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches TabletopKit, RealityKit, SwiftUI, RealityKitContent 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.
• The source does not justify labeling the design protocol-oriented.

Source map

• Official Apple documentation