Rendering hover effects in Metal immersive apps

At a glance

Project structure

Source bundle/
└── CS_HoverEffect/
    └── CS_HoverEffect/
        ├── App/
        │   ├── CompositorServicesHoverEffectApp.swift
        │   ├── CompositorServicesHoverEffectApp+CompositorLayer.swift
        │   └── CompositorServicesHoverEffectApp+Render.swift
        ├── Data/
        │   ├── DataStructures.swift
        │   ├── AppModel.swift
        │   ├── RenderData+Animate.swift
        │   ├── RenderData.swift
        │   └── RenderData+AssetLoad.swift
        ├── TileResolver/
        │   └── TileResolvePipeline.swift
        ├── Views/
        │   └── SettingsView.swift
        ├── Shaders/
        │   └── Shaders.metal
        └── Extensions/
            └── CompositorLayer+FunctionInit.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 3 project/configuration file(s) and 16 source declaration(s).

Overall architecture

flowchart LR
    N1["CompositorServicesHoverEffectApp"]
    N2["SettingsView"]
    N3["AppModel"]
    N4["TileResolvePipeline"]
    N5["CompositorServices APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4
    N4 --> N5

Reference code

CS_HoverEffect/CS_HoverEffect/App/CompositorServicesHoverEffectApp.swift:19 — architecture anchor

@main
struct CompositorServicesHoverEffectApp: App {
    // ...
}

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 Compositor Services.

Ownership and state

classDiagram
    CompositorServicesHoverEffectApp *-- AppModel : appModel
    AppCompositorContent o-- AppModel : appModel
    AppCompositorContent o-- RemoteDeviceIdentifier : remoteDeviceIdentifier
    DrawCallMaterial o-- MTLTexture : texture

Ownership evidence

CS_HoverEffect/CS_HoverEffect/App/CompositorServicesHoverEffectApp.swift:22 — stored dependency or nearest verified ownership anchor

@main
struct CompositorServicesHoverEffectApp: App {
    // ...
    @State var appModel = AppModel()
    // ...
}

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.

Class and protocol design

CS_HoverEffect/CS_HoverEffect/App/CompositorServicesHoverEffectApp.swift:20 — representative type boundary

struct CompositorServicesHoverEffectApp: App {
    // ...
}

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

Access control

Reference code

CS_HoverEffect/CS_HoverEffect/App/CompositorServicesHoverEffectApp.swift:76 — representative boundary

struct AppCompositorContent: CompositorContent {
    // ...
    private var remoteDeviceIdentifier: RemoteDeviceIdentifier?
    // ...
}

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: CompositorServicesHoverEffectApp; Model: AppModel; Pipeline: TileResolvePipeline; Scene: Scene; View: SettingsView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: add, easeInOutQuad, easeOutSine, animate, tap, updatePipelineState, getDepthState, getRenderTexture.
• Files: CS_HoverEffect/CS_HoverEffect/App/CompositorServicesHoverEffectApp.swift, CS_HoverEffect/CS_HoverEffect/Data/AppModel.swift, CS_HoverEffect/CS_HoverEffect/TileResolver/TileResolvePipeline.swift, CS_HoverEffect/CS_HoverEffect/Views/SettingsView.swift, CS_HoverEffect/CS_HoverEffect/Data/RenderData.swift.

Architecture takeaways

• CompositorServicesHoverEffectApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches CompositorServices, MetalKit, 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.
• The source does not justify labeling the design protocol-oriented.

Source map

• Official Apple documentation