its using `wgpu`: a rust library which provides safe graphics api and uses opengl (webgl2), vk, dx, mtl, webgpu as backends. c++ has a similar, but much older project called `bgfx`. If you see wgpu on web, its most likely using webgl2.

webgpu only exists in like the most bleeding edge chrome/firefox builds and even then its very hit and miss. maybe it will start working properly after chrome ships it in september-ish.