Metal.NET

C# bindings for Apple's Metal graphics API, auto-generated from metal-cpp headers.

Installation

dotnet add package Metal.NET

Requirements: .NET 10+, macOS 15+

Quick Start

using Metal.NET;

// Create a Metal device
MTLDevice device = MTLDevice.CreateSystemDefaultDevice();

// Create a command queue
using MTLCommandQueue queue = device.NewCommandQueue();

// Create a library from default.metallib
using MTLLibrary library = device.NewDefaultLibrary();

Memory Management

Ownership Model

Every NativeObject wrapper has a NativeObjectOwnership that controls its lifetime:

Ownership	Dispose() releases	Finalizer releases	Usage
Borrowed	✗	✗	Property getters, objectAtIndex:
Owned	✓	✗	Method return values, out NSError
Managed	✓	✓	Objects created via parameterless constructor (AllocInit)

// Managed — fully C#-created, GC can release as safety net
var desc = new MTLTextureDescriptor();

// Owned — method return, only explicit Dispose releases
using MTLLibrary library = device.NewDefaultLibrary();

// Borrowed — property getter, retained by parent object
MTLDevice device = commandQueue.Device;

Finalization

The GC finalizer only releases Managed instances. Owned wrappers (method returns) must be explicitly disposed. Borrowed wrappers never release:

public enum NativeObjectOwnership { Borrowed, Owned, Managed }

public abstract class NativeObject(nint nativePtr, NativeObjectOwnership ownership) : IDisposable
{
    ~NativeObject()
    {
        if (Ownership is NativeObjectOwnership.Managed) Release();
    }

    public void Dispose() { Release(); GC.SuppressFinalize(this); }
}

Project Structure

Metal.NET.slnx
├── Metal.NET/                            ← Binding library (targets .NET 10, macOS 15+)
│   ├── Common/
│   │   ├── NativeObject.cs               ← NativeObjectOwnership enum + INativeObject<TSelf> + base class
│   │   ├── ObjectiveCRuntime.cs          ← P/Invoke to libobjc.dylib (objc_msgSend)
│   │   ├── Selector.cs                   ← ObjC selector with implicit string conversion
│   │   ├── Bool8.cs                      ← ObjC BOOL mapped to a single byte
│   │   └── MTLStructs.cs                ← Blittable structs (MTLOrigin, MTLSize, etc.)
│   ├── Foundation/                       ← Hand-written Foundation types
│   │   ├── NSString.cs                   ← Bidirectional string conversion
│   │   ├── NSError.cs                    ← Error wrapper with LocalizedDescription
│   │   ├── NSArray.cs                    ← NSArray ↔ T[] conversion utilities
│   │   ├── NSURL.cs                      ← File URL creation
│   │   └── NSAutoreleasePool.cs          ← Autorelease pool management
│   ├── Metal/                            ← Auto-generated Metal API (352 files)
│   ├── MetalFX/                          ← Auto-generated MetalFX (18 files)
│   └── QuartzCore/                       ← Auto-generated QuartzCore (2 files)
│
└── Metal.NET.Generator/                  ← Offline code generator
    ├── Program.cs                        ← Entry point
    ├── Generator.cs                      ← Orchestrator (parser → emitter pipeline)
    ├── CppParser.cs                      ← Regex-based metal-cpp header parser
    ├── CSharpEmitter.cs                  ← C# source code emitter
    ├── TypeMapper.cs                     ← C++ → C# type mapping and naming
    ├── GeneratorContext.cs               ← Shared state between parser and emitter
    ├── Models.cs                         ← Data models (EnumDef, ClassDef, MethodInfo, etc.)
    └── metal-cpp/                        ← metal-cpp headers (generation source)

Updating Bindings

1. Download the latest metal-cpp archive.

2. Replace the contents of Metal.NET.Generator/metal-cpp/.

3. Run the generator:

   dotnet run --project Metal.NET.Generator

4. Build and verify:

   dotnet build Metal.NET

Disclaimer

This library was built with AI assistance. It has undergone preliminary testing to verify basic usability, but has not been exhaustively validated in production scenarios. If you plan to use it in a real project, please ensure it meets your requirements through thorough testing.

Alternatives

If you are looking for more mature or alternative Metal bindings for .NET, consider:

• SharpMetal — A community-maintained C# Metal binding library.
• .NET net-macos / net-ios TFM — Apple platform targets shipped with .NET that include official Metal API bindings via dotnet/macios.

License

This project is licensed under the MIT License.

Trademarks

"Metal" is a trademark of Apple Inc. This project is not affiliated with or endorsed by Apple Inc.

Third-Party Notices

See THIRD-PARTY-NOTICES.md for details on third-party components used in this project.