[brundolf]

You don't really have the choice with graphics either. The GPU keeps mesh and texture data in memory between frames, and I would imagine something similar happens for lighting, etc at some layer in the pipeline. Reconstructing the entire scene every time would not be feasible.

[gw]

You can still hold on to references to textures and meshes you uploaded to the GPU without using a full-blown scene graph. Some state is necessary no doubt, but this seems more like unnecessary state that could be replaced by something more direct. But i don't know, i'm not familiar with three.js; the click handlers seem useful.

[brundolf]

Regardless: the reason for having a base API be imperative is usually because it's maximally flexible and performant. By your own admission, any reactive API for 3D rendering will at least have to hold on to references to GPU objects in-between iterations, which means it could never be a truly stateless API; it would always be an abstraction over something stateful.

So given that constraint, I think it's better for the base API not to hide that statefulness behind an abstraction, and to leave the abstracting to a higher-level API