WGPUC — WebGPU in C99

⚠️ EXPERIMENTAL – This project is under active development and APIs may change without notice. Use at your own risk.

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WGPUC is a pure C99 implementation of the WebGPU standard, providing a cross-platform graphics and compute API with multiple backend support.

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Looking for a tiny web development ecosystem? See: Minimum Viable Web

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Supported Backends

Backend	Platform	Status	Notes
Vulkan	Windows, Linux, Android	~95% (production-ready)	Primary backend. Default blend state, no async submit
D3D12	Windows 10+	~90%	Blocked end-to-end on WGSL→HLSL wiring
D3D11	Windows 7+	~90%	Same WGSL→HLSL blocker
OpenGL / GLES	Currently Windows-only	~50%	Pipeline/compute incomplete; cross-platform context modules pending
Metal	macOS, iOS	Scaffolding (~0% end-to-end)	Pure-C Objective-C runtime bridge exists; no shader path to MSL yet

See TRACKING.md for the authoritative per-backend board and per-backend review docs under docs/.

Features

• Pure C99 — No language dependencies in the core library
• WebGPU Standard Compliant — Follows the W3C WebGPU specification
• Multi-Backend — Single API surface across Vulkan, Metal, D3D12, D3D11, and OpenGL
• Embeddable — Designed for integration into games, engines, and applications

Layout

• CMakeLists.txt — Top-level build entrypoint with validation toggles
• include/ — Public headers (wgpu.h, wgpu_platform.h, wgpu_limits.h)
• src/ — Implementation:
  • api/ — API entrypoints
  • core/, val/ — Resource/state management and validation logic
  • hal/ — Hardware abstraction layer interface
  • shader/ — Shader compilation and reflection
  • backends/ — Platform-specific backends (Vulkan, Metal, D3D12, D3D11, GL)

Build

Basic Build

cmake -S . -B build -DWGPU_ENABLE_VALIDATION=ON
cmake --build build

Shader Translation

WGPUC has two WGSL translation paths:

• Built-in pure-C99 translator (src/shader/wgslc/): unconditionally compiled, emits GLSL/MSL/HLSL. No external toolchain. Currently not yet wired into the D3D/Metal/GL pipeline-creation paths — see the roadmap below.
• Optional naga path (WGPU_ENABLE_WGSL_TRANSLATION=ON): uses naga via a Rust crate for higher-fidelity translation. Requires Rust/Cargo installed.

# (Optional) install Rust if you want the naga path
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

cmake -S . -B build -DWGPU_ENABLE_WGSL_TRANSLATION=ON
cmake --build build

Test

cmake -S . -B build -DWGPU_BUILD_TESTS=ON
cmake --build build
ctest --test-dir build --output-on-failure

Key Resources

• WebGPU Specification — The W3C Editor's Draft
• WebGPU Shading Language (WGSL) — Shader language specification

Backend Feature Matrix

This is a per-backend feature tracker for the implementation. The authoritative status board is TRACKING.md (with enforcement), and intentional gaps/stubs are tracked in STUB_REGISTRY.md.

Legend: ✅ Implemented | ⚠️ Partial | ❌ Not Implemented

Core Object Model

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
Adapter enumeration	✅	✅	✅	✅	✅	All backends enumerate hardware
Device creation	✅	✅	✅	✅	✅	Queue created with device
Limits negotiation	✅	✅	✅	⚠️	⚠️	Vulkan/Metal query actual limits; others use defaults

Surfaces & Present

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
Surface creation	✅	✅	✅	✅	✅	Platform-specific (HWND, CAMetalLayer, etc.)
Swapchain configure	✅	✅	✅	✅	✅	DXGI/Vulkan swapchain, GL FBOs
Acquire texture	✅	✅	✅	✅	✅	Returns current backbuffer view
Present	✅	✅	✅	✅	✅	SwapBuffers/Present/drawable present

Buffers

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
Create buffer	✅	✅	✅	✅	✅	All usage flags supported
Map/Unmap	✅	✅	✅	✅	✅	Persistent mapping where available
Queue write buffer	✅	✅	✅	✅	✅	Staging + copy or direct write
Buffer destroy	✅	✅	✅	✅	✅	Resource cleanup

Textures

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
Create texture	✅	✅	✅	✅	✅	2D textures; 3D/array partial
Texture views	✅	✅	✅	✅	⚠️	GL emulates views (no GL 4.3 texture_view)
Depth/stencil formats	✅	✅	✅	✅	⚠️	GL limited format support
Color formats	✅	✅	✅	✅	⚠️	GL subset of formats

Samplers

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
Create sampler	✅	✅	✅	✅	✅	Filter/wrap/LOD/compare
Comparison samplers	✅	✅	✅	✅	✅	Shadow sampling

Bind Groups & Layouts

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
Bind group layout	✅	✅	✅	✅	✅	Descriptor set layouts / root signature
Bind group creation	✅	✅	✅	✅	✅	Resource binding
Buffer bindings	✅	✅	✅	✅	✅	Uniform/storage buffers
Texture bindings	✅	✅	✅	✅	✅	Sampled textures
Sampler bindings	✅	✅	✅	✅	✅	Separate samplers
Storage texture bindings	✅	✅	⚠️	⚠️	⚠️	UAV/imageStore support varies

Shader Modules

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
WGSL ingestion	✅	⚠️	⚠️	⚠️	⚠️	In-tree wgslc translator exists but not yet wired to Metal/D3D/GL pipeline creation
SPIR-V ingestion	✅	❌	❌	❌	❌	Native Vulkan only
Shader reflection	✅	⚠️	⚠️	⚠️	⚠️	SPIR-V reflection is primary

Pipelines

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
Render pipeline	✅	⚠️	✅	✅	✅	Metal pipeline exists but has no shader source
Compute pipeline	✅	⚠️	✅	✅	⚠️	GL requires 4.3+; Metal shader-path blocker
Pipeline layout	✅	✅	✅	✅	✅	Derived or explicit
Vertex input state	✅	✅	✅	⚠️	✅	D3D11 input layout partial
Depth/stencil / primitive / blend / multisample state	⚠️	⚠️	⚠️	⚠️	⚠️	Descriptor fields partially exposed; blend state and full primitive/stencil state pending

Render Passes

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
Begin/end render pass	✅	✅	✅	✅	✅	Framebuffer setup
Color attachments	✅	✅	✅	✅	✅	Multiple render targets
Depth/stencil attachment	✅	✅	⚠️	⚠️	✅	D3D partial
Load/store ops	✅	✅	✅	✅	✅	Clear/load/store
Set pipeline	✅	✅	✅	✅	✅	Bind render pipeline
Set bind group	✅	✅	✅	✅	✅	Bind descriptor sets
Set vertex buffer	✅	✅	⚠️	⚠️	✅	D3D vertex buffer binding partial
Set index buffer	✅	✅	⚠️	⚠️	✅	D3D index buffer binding partial
Draw	✅	✅	✅	✅	✅	Non-indexed draw
Draw indexed	✅	✅	⚠️	⚠️	✅	D3D indexed draw partial
Draw instanced	✅	✅	✅	✅	✅	Instance drawing

Compute Passes

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
Begin/end compute pass	✅	⚠️	✅	✅	⚠️	GL requires 4.3+; Metal shader-path blocker
Set pipeline	✅	⚠️	✅	✅	⚠️	GL requires 4.3+
Set bind group	✅	⚠️	✅	✅	⚠️	GL requires 4.3+
Dispatch	✅	⚠️	✅	✅	⚠️	GL requires 4.3+

Command Encoding

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
Copy buffer to buffer	✅	✅	✅	⚠️	✅	D3D11 via mapped memory
Copy buffer to texture	⚠️	⚠️	⚠️	⚠️	⚠️	Partial across all backends
Copy texture to buffer	⚠️	⚠️	⚠️	⚠️	⚠️	Partial across all backends
Queue submit	✅	✅	✅	✅	✅	Command buffer execution

Synchronization

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
Queue submit fence	✅	✅	✅	✅	✅	Wait for completion
Resource barriers	✅	⚠️	✅	❌	❌	Vulkan/D3D12 explicit barriers

Validation & Testing

Feature	Vulkan	Metal	D3D12	D3D11	GL/GLES	Notes
Validation layer	⚠️	⚠️	⚠️	⚠️	⚠️	Minimal; descriptor/usage/limits validation pending
Backend tests	✅	⚠️	⚠️	⚠️	✅	Happy-path only; see tests/backend/*

Not yet on any backend

Query sets (occlusion, timestamp), render bundles, indirect draw/dispatch, debug markers, dynamic state (viewport/scissor/blend constant/stencil ref), texture-to-texture copy, ClearBuffer, async APIs (mapAsync, requestAdapter/Device callbacks, onSubmittedWorkDone), error scopes, uncaptured-error and device-lost callbacks, real feature negotiation, getCompilationInfo(). Tracked in TRACKING.md and .cursor/plans/.

Roadmap

Near-term focus: wire the in-tree wgslc translator into Metal/D3D12/D3D11/GL pipeline creation, fill the missing command-encoding and dynamic-state APIs, add an async/error model, and build out the validation layer.

Detailed per-area plans live in .cursor/plans/; authoritative status in TRACKING.md.

License

WGPUC is MIT licensed. See LICENSE.MIT.