1. HTML elements live inside
<canvas layoutsubtree> elements
2. drawElementImage() captures live DOM into canvas bitmaps
3. Canvas bitmaps become WebGL textures via Three.js CanvasTexture
4. Walk around and see live-updating HTML on 3D surfaces
This pipeline is impossible without HTML-in-Canvas — previously you needed html2canvas or dom-to-image, which are slow, lossy, and cannot update at 60 fps.