🔭 GPU - Cross platform GPU library (based on Metal API)

This is cross platform GPU library based on Apple's Metal API. Library is written in C language and it provides and will provide C API. Since this is C API, language bindings can be written for any language.

Status (In Progress)

I'll announce after first release is ready.

Shading Language

I'll try to create new shading language that called ("Universal Shading Language") (https://github.com/UniversalShading). GPU library will use that high level language for shading. Shading language will be translated/compiled into GLSL, HLSL or Metal Shaders... Since GPU library will be cross platform, this will also make shading language cross platform...

Design (TODO)

GPU library provides GPUApi structure and headers. In theory any GPU API e.g. Metal, Vulkan, DirectX, OpenGL... could be bind this GPU library.

Switching between GPU APIs will be easy: GPUSwitchGPUApi(GPU_BACKEND_METAL); or auto select GPUSwitchGPUApiAuto().

This section and others will be documented in detail later...

Naming Conventions

TODO: GPUSetFrontFace() vs gpuSetFrontFace() vs gpu_set_frontface(), feedbacks

Design Sample

I have translated Xcode's Game template project's renderer codes into GPU library (This may be obsoleted by time):

- (void)viewDidLoad

  GPUSwitchGPUApi(GPU_BACKEND_METAL);

  device   = GPUCreateSystemDefaultDevice();
  pipeline = GPUNewPipeline(GPUPixelFormatBGRA8Unorm_sRGB);
  library  = GPUDefaultLibrary(device);

  vertFunc = GPUNewFunction(library, "vertexShader");
  fragFunc = GPUNewFunction(library, "fragmentShader");
  vert     = GPUNewVertexDesc();

  GPUAttrib(vert, VertexAttributePosition, GPUFloat3, 0, BufferIndexMeshPositions);
  GPUAttrib(vert, VertexAttributeTexcoord, GPUFloat2, 0, BufferIndexMeshGenerics);

  GPULayout(vert, BufferIndexMeshPositions, 12, 1, GPUPerVertex);
  GPULayout(vert, BufferIndexMeshGenerics,  8,  1, GPUPerVertex);

  GPUSetFunction(pipeline, vertFunc, GPU_FUNCTION_VERT);
  GPUSetFunction(pipeline, fragFunc, GPU_FUNCTION_FRAG);
  GPUSetVertexDesc(pipeline, vert);

  GPUColorFormat(pipeline, 0, (GPUPixelFormat)_view.colorPixelFormat);
  GPUDepthFormat(pipeline, (GPUPixelFormat)_view.depthStencilPixelFormat);
  GPUStencilFormat(pipeline, (GPUPixelFormat)_view.depthStencilPixelFormat);
  GPUSampleCount(pipeline, (uint32_t)_view.sampleCount);

  renderState          = GPUNewRenderState(device, pipeline);
  depthStencil         = GPUNewDepthStencil(GPUCompareFunctionLess, true);
  depthStencilState    = GPUNewDepthStencilState(device, depthStencil);

  dynamicUniformBuffer = GPUNewBuffer(device, uniformBufferSize, GPUResourceStorageModeShared);
  commandQueue         = GPUNewCommandQueue(device);

- drawInMTKView

- (void)drawInMTKView:(nonnull MTKView *)view {
  dispatch_semaphore_wait(_inFlightSemaphore, DISPATCH_TIME_FOREVER);
  
  cmdb = GPUNewCommandBuffer(commandQueue, _inFlightSemaphore, cmdOnComplete);
  
  [self _updateDynamicBufferState];
  [self _updateGameState];
  
  if ((pass = GPUPassFromMTKView(view))) {
    GPURenderCommandEncoder *rce;

    rce = GPUNewRenderCommandEncoder(cmdb, pass);
    {
      GPUSetFrontFace(rce, GPUWindingCounterClockwise);
      GPUSetCullMode(rce, GPUCullModeBack);
      GPUSetRenderState(rce, renderState);
      GPUSetDepthStencil(rce, depthStencilState);

      GPUSetVertexBuffer(rce, dynamicUniformBuffer, uniformBufferOffset, BufferIndexUniforms);
      GPUSetFragmentBuffer(rce, dynamicUniformBuffer, uniformBufferOffset, BufferIndexUniforms);
      GPUSetFragmentTexture(rce, _colorMap, TextureIndexColor);
      
      GPULoadAndDrawMTKMesh(rce, _mesh);
    }

    GPUEndEncoding(rce);
    GPUPresent(cmdb, view.currentDrawable);
  }

  GPUCommit(cmdb);
}

Trademarks

Apple name/logo and Metal are trademarks of Apple Inc. Vulkan and OpeenGL are trademarks of Khronos Group. DirectX is trademark of Microsoft Corp.