OK, this comment convinced me to give that a shot.

Here's a thing I made in Three.js this morning - a Nudibranch themed Faberge Egg: https://static.simonwillison.net/static/2026/Hidden-Reef-Egg... (77KB)

I just asked Claude (Opus 5.5 Medium running in regular Claude Chat) to port that to Vanilla JS, in the same thread where it had built it, and got this: https://static.simonwillison.net/static/2026/Hidden-Reef-Egg... (98KB)

They aren't identical - you can see what Claude said about that in the transcript (I don't fully understand why it differed): https://claude.ai/share/e56d163e-2793-4677-aa11-191d5058b414

But yeah, it turns out Claude Opus 5.5 is perfectly capable of 3D modeling in Vanilla JS + WebGL without Three.js.

In eyeballing the code I find the Three.js slightly easier to understand myself, but I rarely look at the code for these 3D projects so that isn't a particularly big deal.

I made an app+DSL for making 3D things with Opus 5 that did a pretty good job without three.js: https://fab.ooer.com/ (setting the depth of field to about 0.3 and then switching Quality to 'traced' looks really nice.)

I don't know your prompt but I'd suggest also adding things like "use best GPU practices" and "use techniques AAA games use to achieve the best performance and best visuals", "make it beautiful like a AAA game" etc...

Also, comparing, the three.js version downloaded 395k representing 1.6meg of data. The raw version downloaded 109k representing 200k of data. You listed the three.js version is as smaller but it's not smaller, it had to download three.js

The performance got way better on my machine, 120ms (Vanilla) VS 504ms (Three.js) INP[0].

[0]: https://web.dev/articles/inp

Three.js egg : 2,61 Mo

Vanilla : 173,4 ko

Vanilla gets way better FPS on my M1.