Combining blit and compute operations in a single pass

At a glance

Project structure

Source bundle/
├── Renderer/
│   ├── Metal4Renderer.m
│   ├── Shaders.metal
│   └── ShaderTypes.h
└── Application/
    ├── ViewController.m
    ├── main.m
    ├── WindowSceneDelegate.m
    ├── AppDelegate.h
    ├── AppDelegate.m
    └── ViewController.h

Structure observations

• The entry/composition boundary and renderer or operation boundary are separate in the source; Metal4Renderer is the principal feature coordinator.
• GPU-specific logic stays in Metal shader files; shared headers bridge host/shader layouts where present.
• The tree above is intentionally pruned to composition, resource, and shader files.

Overall architecture

flowchart LR
    N1["ViewController"]
    N2["Metal4Renderer"]
    N3["combined command-encoder setup"]
    N4["blit and compute commands in one pass"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

Renderer/Metal4Renderer.m:507 — feature handoff or setup anchor

@implementation Metal4Renderer
// ...
- (void)encodeChyronTextureCopy:(id<MTL4ComputeCommandEncoder>)computeEncoder
// ...
@end

Interpretation

This is the dominant control/data path: platform code composes Metal4Renderer; that object controls combined command-encoder setup; GPU-visible work ends in blit and compute commands in one pass. The arrows summarize responsibility transfer, not a claim that every node directly calls the next.

Ownership and state

classDiagram
    ViewController *-- Metal4Renderer : renderer

Ownership evidence

Application/ViewController.m:28 — ViewController creates and stores renderer

@implementation ViewController
// ...
        renderer = [[Metal4Renderer alloc] initWithView:view];
// ...
@end

Class and protocol design

Framework delegate conformance is a callback seam; the source does not justify calling the whole app protocol-oriented.

Access control

This sample does not use Swift private, fileprivate, or public for its native boundary. Objective-C/Objective-C++ use header versus implementation placement, C++ uses access specifiers/linkage, Python uses module conventions, and Metal entry points cross a compiled-library boundary; these are not Swift access levels.

Logic ownership and placement

Shader boundary reference

Renderer/Shaders.metal:89 — grayscale compute entry point used by the combined pass

kernel void

Design patterns

Naming conventions

• Role suffixes make ownership visible: ViewController, Metal4Renderer, AppDelegate, WindowSceneDelegate.
• Method names describe setup or encoding actions: application, viewDidLoad, scene, sceneDidDisconnect, initWithView, loadImageToTexture, createCompiler.
• Shader entry points use stage/operation names: samplingShader, convertToGrayscale.
• Names favor concrete domain roles and target-local types; no broad public library namespace is introduced.

Architecture takeaways

• Keep ViewController focused on composition; Metal4Renderer is the owner of combined command-encoder setup.
• Treat blit and compute commands in one pass as a separate execution/compilation boundary with explicit resource and data-layout contracts.
• The verified ownership edge is ViewController → renderer; broader exclusive ownership is not inferred.
• Access-control rationale follows concrete language boundaries rather than translating every header or shader symbol into Swift terms.

Source map

• Official Apple documentation