Web Assembly RHI backend for WebGPU/GPUWeb

GPUWeb is an upcoming web graphics API which abstracts over Vulkan, D3D, and Metal. For Qt on the web it would be natural to implement a backend for the RHI graphics abstraction (QTBUG-70287).

The backend can be developed on a desktop system, for example by building Dawn (Chrome) or gfx-rs/wgpu (Rust with C bindings). The WebGPU API is settling down now, but is not frozen yet. There are two competing proposals for the shader language: SPIR-V and WHLSL .

For usage on the Web, then either 1) implement a JavaScript translation layer, or 2) wait for WebAssembly host bindings.

Summary:

Issue: Rendering advanced graphics could sometimes use additional performance. GPUWeb is an upcoming web graphics API which abstracts over Vulkan, D3D, and Metal, being standardised in W3C.

Solution: Qt Web Assembly webGPU support for graphics rendering to offer better performance.