While we could use ImageBitmapRenderingContext in the main thread and blit textures using that instead of Canvas2DRenderingContexts in a more efficient way, the bitmap rendering and offscreen canvas APIs are related and if supported, should both be available, meaning we can always do rendering in a worker for this codepath. We could transferControlToOffscreen for each model element, and then we'd have multiple WebGL contexts in a worker, or multiple workers, but unclear if that's more performant than a single context in a worker sending out textures. Also if one can crop the bitmaps created from there.

More info: #10 (comment)

Dependent on #10 in some cases, but after writing this, now I'm not sure.