Generating procedural textures

At a glance

Project structure

Source bundle/
└── RealityKit-Drawable/
    ├── App/
    │   └── Drawable.swift  # Drawable
    ├── Systems/
    │   ├── DrawableQueueComponent.swift  # DrawableQueueComponent, DrawableComponentError
    │   └── DrawableQueueSystem.swift  # DrawableQueueSystem
    ├── Textures/
    │   ├── ProceduralTextureGenerator.swift  # ProceduralTextureGenerator, ProceduralTextureGeneratorError
    │   └── DynamicTextureShaders.metal  # Args
    └── Views/
        ├── DrawableView.swift  # DrawableView
        └── EntityView.swift  # EntityView

Structure observations

• The runtime boundary is WindowGroup; the pruned tree lists only files that explain lifecycle, state, or framework integration.
• App code is split into role-named views, models, managers, providers, components, or systems.

Overall architecture

flowchart LR
    Drawable_1["Drawable"]
    WindowGroup_2["WindowGroup"]
    DrawableView_3["DrawableView"]
    RealityView_entity_graph_4["RealityView entity graph"]
    RealityKit_components_and_systems_5["RealityKit components and systems"]
    Drawable_1 --> WindowGroup_2
    WindowGroup_2 --> DrawableView_3
    DrawableView_3 --> RealityView_entity_graph_4
    RealityView_entity_graph_4 --> RealityKit_components_and_systems_5

Reference code

RealityKit-Drawable/App/Drawable.swift:11 — the app or executable entry declares the outer scene lifecycle.

struct Drawable: App {
    var body: some Scene {
        WindowGroup {
            DrawableView()
        }
    }
}

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
    DrawableQueueComponent --> MTLComputePipelineState : pipeState
    DrawableQueueComponent --> TextureResource : texture
    DrawableQueueComponent --> MTLTexture : mtlTextureRead
    DrawableQueueComponent --> MTLTexture : mtlTextureWrite

Ownership evidence

RealityKit-Drawable/Systems/DrawableQueueComponent.swift:25 — representative stored state or the nearest verified lifecycle anchor.

struct DrawableQueueComponent: Component {
    // ...
    let pipeState: MTLComputePipelineState
    // ...
}

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

RealityKit-Drawable/App/Drawable.swift:11 — representative visibility boundary.

struct Drawable: App {
    // ...
}

Logic ownership and placement

Design patterns

Naming conventions

• Role suffixes are evidence, not decoration: View: DrawableView, EntityView.
• ECS names pair data and behavior: components DrawableQueueComponent; systems DrawableQueueSystem.
• Protocols: no app-defined protocol in the reviewed source.
• Commands use verb-led methods: update, generate.
• Files generally match their primary type; Views, Models, Managers, Providers, Components, Systems, and Packages folders describe architectural roles where present.

Architecture takeaways

• Treat Drawable 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.
• Use RealityKit components for per-entity data and systems for repeated simulation instead of a monolithic view model.

Source map

• Official Apple documentation