Generating interactive geometry with RealityKit

At a glance

Project structure

Source bundle/
└── GeneratingInteractiveGeometry/
    └── GeneratingInteractiveGeometry/
        ├── GeneratingInteractiveGeometrySampleApp.swift
        ├── Compute/
        │   └── ComputeSystem.swift
        ├── HeightMapMeshView.swift
        ├── HeightMapMesh/
        │   ├── HeightMapGenerator.swift
        │   ├── HeightMapMesh.swift
        │   ├── HeightMap.swift
        │   ├── HeightMapMeshEntity.swift
        │   ├── MeshParams.h
        │   └── PlaneMesh.swift
        ├── Sine Wave/
        │   └── SineWaveHeightMapGenerator.swift
        ├── Terrain/
        │   └── TerrainHeightMapGenerator.swift
        └── Water/
            └── WaterSurfaceHeightMapGenerator.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 20 source declaration(s).

Overall architecture

flowchart LR
    N1["GeneratingInteractiveGeometrySampleApp"]
    N2["HeightMapMeshView"]
    N3["Generator"]
    N4["RealityKit APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

GeneratingInteractiveGeometry/GeneratingInteractiveGeometry/GeneratingInteractiveGeometrySampleApp.swift:10 — architecture anchor

@main
struct GeneratingInteractiveGeometrySampleApp: App {
    // ...
        WindowGroup {
            HeightMapMeshView()
        }
    // ...
}

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-- TimeInterval : deltaTime
    ComputeUpdateContext o-- MTLCommandBuffer : commandBuffer
    ComputeUpdateContext o-- MTLComputeCommandEncoder : computeEncoder
    ComputeSystemComponent o-- ComputeSystem : computeSystem

Ownership evidence

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

struct ComputeUpdateContext {
    // ...
    let deltaTime: TimeInterval
    // ...
}

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

GeneratingInteractiveGeometry/GeneratingInteractiveGeometry/Compute/ComputeSystem.swift:23 — representative execution boundary

protocol ComputeSystem {
    @MainActor
    func update(computeContext: 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

GeneratingInteractiveGeometry/GeneratingInteractiveGeometry/Compute/ComputeSystem.swift:22 — representative type boundary

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

The source explicitly defines local protocol relationships: HeightMapMesh → ComputeSystem, SineWaveHeightMapGenerator → HeightMapGenerator, TerrainHeightMapGenerator → HeightMapGenerator, WaterSurfaceHeightMapGenerator → HeightMapGenerator.

Access control

Reference code

GeneratingInteractiveGeometry/GeneratingInteractiveGeometry/HeightMapMesh/HeightMap.swift:16 — representative boundary

@MainActor
struct HeightMap {
    // ...
    private let deriveNormalsPipeline: MTLComputePipelineState = makeComputePipeline(named: "deriveNormalsFromHeightMap")!
    // ...
}

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: GeneratingInteractiveGeometrySampleApp; Component: ComputeSystemComponent; Generator: Generator, HeightMapGenerator, SineWaveHeightMapGenerator, TerrainHeightMapGenerator, WaterSurfaceHeightMapGenerator; System: ComputeDispatchSystem, ComputeSystem; View: HeightMapMeshView.
• Protocols: ComputeSystem, HeightMapGenerator.
• Methods: update, setHeightMapGenerator, createScene, reset, generateHeightMap, resetWaterSurface, disturbWaterSurface, runWaterSimulation.
• Files: GeneratingInteractiveGeometry/GeneratingInteractiveGeometry/GeneratingInteractiveGeometrySampleApp.swift, GeneratingInteractiveGeometry/GeneratingInteractiveGeometry/Compute/ComputeSystem.swift, GeneratingInteractiveGeometry/GeneratingInteractiveGeometry/HeightMapMeshView.swift, GeneratingInteractiveGeometry/GeneratingInteractiveGeometry/HeightMapMesh/HeightMapGenerator.swift, GeneratingInteractiveGeometry/GeneratingInteractiveGeometry/Sine Wave/SineWaveHeightMapGenerator.swift, GeneratingInteractiveGeometry/GeneratingInteractiveGeometry/Terrain/TerrainHeightMapGenerator.swift.

Architecture takeaways

• GeneratingInteractiveGeometrySampleApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches RealityKit, Metal, metal_stdlib, simd 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