Adjusting the level of detail using Metal mesh shaders

At a glance

Project structure

Source bundle/
├── MeshShadersMetalCPP/
│   ├── Application/
│   │   ├── main.m
│   │   ├── AAPLAppDelegate.h
│   │   ├── AAPLAppDelegate.m
│   │   ├── AAPLViewController.h
│   │   ├── AAPLViewController.m
│   │   ├── WindowSceneDelegate.h
│   │   └── WindowSceneDelegate.m
│   ├── Adapter/
│   │   ├── AAPLRendererAdapter.mm
│   │   └── AAPLRendererAdapter.h
│   └── Renderer/
│       ├── AAPLShaders.metal
│       └── AAPLRenderer.cpp
└── metal-cpp/
    └── SingleHeader/
        └── MakeSingleHeader.py

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: C++, C/Objective-C header, Metal, Objective-C, Objective-C++, Python.
• The verified tree contains 8 project/configuration file(s) and 11 source declaration(s).

Overall architecture

flowchart LR
    Bundle["Sample bundle"]
    V1["MeshShadersMetalCPP"]
    V2["metal-cpp"]
    Boundary["Metal / MetalKit APIs"]
    Bundle --> V1
    V1 --> Boundary
    Bundle --> V2
    V2 --> Boundary

Reference code

MeshShadersMetalCPP/Application/main.m:13 — architecture anchor

#if TARGET_OS_OSX
int main(int argc, const char* argv[])
{
    return NSApplicationMain(argc, argv);
}
#endif

Interpretation

The branches represent separate entry-bearing project variants in the downloaded bundle, not runtime calls between those variants. Each branch is intentionally collapsed at the documented framework boundary; the detailed target-local flow remains in the cited files. Ownership is claimed only where the next section cites a stored property or assignment.

Ownership and state

classDiagram
    AAPLAppDelegate o-- PlatformWindow : window
    WindowSceneDelegate o-- UIWindow : window

Ownership evidence

MeshShadersMetalCPP/Application/AAPLAppDelegate.h:29 — stored dependency or nearest verified ownership anchor

#if TARGET_OS_OSX
@property (strong, nonatomic) PlatformWindow* window;
#endif

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.

No source-visible execution, scheduling, or synchronization boundary was found in the indexed source.

@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.

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

MeshShadersMetalCPP/Application/AAPLAppDelegate.h:26 — representative type boundary

@interface AAPLAppDelegate : PlatformAppDelegate

#if TARGET_OS_OSX
@property (strong, nonatomic) PlatformWindow* window;
#endif

@end

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

Access control

Reference code

MeshShadersMetalCPP/Application/AAPLAppDelegate.h:29 — representative boundary

#if TARGET_OS_OSX
@property (strong, nonatomic) PlatformWindow* window;
#endif

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

Main application flow

sequenceDiagram
    participant AAPLViewController
    participant _viewdevice
    participant NSView
    participant UIView
    participant UIColor
    participant AAPLRendererAdapter
    participant _renderer
    AAPLViewController->>AAPLViewController: viewDidLoad()
    AAPLViewController->>_viewdevice: supportsFamily()
    AAPLViewController->>_viewdevice: supportsFamily()
    AAPLViewController->>NSView: initWithFrame()
    AAPLViewController->>UIView: initWithFrame()
    AAPLViewController->>UIColor: initWithRed()
    AAPLViewController->>AAPLRendererAdapter: initWithMtkView()
    AAPLViewController->>_renderer: drawableSizeWillChange()

Reference code

MeshShadersMetalCPP/Application/AAPLViewController.m:57 — viewDidLoad()

- (void)viewDidLoad
{
    [super viewDidLoad];

    _view = (MTKView *)self.view;
    _view.device = MTLCreateSystemDefaultDevice();
    NSAssert(_view.device, @"The app couldn't get a GPU device.");
    NSLog(@"Device: %@", _view.device.name);

    // Check whether the GPU device supports mesh shaders.
    if (![_view.device supportsFamily:MTLGPUFamilyMac2] &&
        ![_view.device supportsFamily:MTLGPUFamilyApple7])
    {
        NSLog(@"This GPU device doesn't support mesh shaders.");

        // Create an empty view and return.
#if TARGET_OS_OSX
        self.view = [[NSView alloc] initWithFrame:_view.frame];
#elif TARGET_OS_IPHONE
        self.view = [[UIView alloc] initWithFrame:_view.frame];
        self.view.backgroundColor = [[UIColor alloc] initWithRed:1.0 green:0.0 blue:0.0 alpha:1.0];
#endif
        return;
    }

    _renderer = [[AAPLRendererAdapter alloc] initWithMtkView:_view];
    NSAssert(_renderer, @"Renderer failed initialization");

    [_renderer drawableSizeWillChange:_view.bounds.size];

    // Configure the view to use this class instance to handle the draw and resize events.
    _view.delegate = self;
}

Naming conventions

• Types: Adapter: AAPLRendererAdapter; Controller: AAPLViewController; Delegate: AAPLAppDelegate, WindowSceneDelegate.
• Protocols: no local protocol declaration in the scanned source.
• Methods: initWithMtkView, dealloc, device, drawInMTKView, drawableSizeWillChange, setRotationSpeed, setTranslation, setLODChoice.
• Files: MeshShadersMetalCPP/Application/AAPLAppDelegate.h, MeshShadersMetalCPP/Adapter/AAPLRendererAdapter.mm, MeshShadersMetalCPP/Application/AAPLAppDelegate.m, MeshShadersMetalCPP/Adapter/AAPLRendererAdapter.h, MeshShadersMetalCPP/Application/AAPLViewController.h, MeshShadersMetalCPP/Application/AAPLViewController.m.

Architecture takeaways

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