· GPT-5.6 Terra · Same prompt: a million-particle three.js black hole

The run where the code was right and the camera was inside the light source

Same prompt, GPT-5.6 Terra, one shot: 759 lines, a million particles, zero errors, and every HUD and ?t= hook implemented. But the camera and the scene scale were never reconciled, so the frame is one enormous white arc. Nothing an assertion can check failed. It is still a failure.

The frame is filled by one enormous white arc of light with no visible black hole or accretion disk structure; the HUD at upper left reads 20.0 FPS and 1,000,000 particles
Run the demo WebGL · uses your GPU
drag to orbit · scroll to zoom · space to pause · 1/2/3 for palettes Open full screen ↗

The on-screen labels are in Chinese: this is the model's verbatim output from an experiment run in Chinese, and editing it would make the artifact something other than what was measured.

How it was made

Model
GPT-5.6 Terra
us.openai.gpt-5.6-terra
How
one shot
Reasoning effort
high
Output tokens
12.2k
Wall time
2m 5s
Artifact
759 lines, one file
Error feedback
none

This one is published on its own because it is the cleanest example of a failure that static metrics cannot see.

On reasoning, code, tool calling and vision benchmarks the three models are close to even. This run also genuinely works: __DEMO_READY is true, page and console errors are both zero, the HUD reports 20.0 FPS, 1,000,000 particles and the cyan-violet palette, and the ?t= determinism contract holds. Every hook that can be asserted automatically was implemented.

But the camera position and the scene scale were never reconciled, which puts the camera inside the glowing body: the frame is one enormous white arc edge, with no black hole, no disk and no dust to speak of. Not one automated check fails. Only a person looking at it can tell it is wasted.

Two other numbers are far apart as well: 12.3 seconds to initialise against 537 milliseconds for the Astra run, and 3.43 FPS against 8.66 under software rendering.

Controls: drag to orbit, scroll to zoom, space to pause, 1/2/3 for palettes, ?t=7.5 to freeze the clock.

Same prompt, other runs

A black hole in deep space with an orange and cyan accretion disk, surrounded by a million particles of star dust, with an EVENT HORIZON title and HUD readout at the upper left
GPT-6 Astra
Event horizon in one shot: a million-particle black hole
A pale blue-white haze fills the frame with almost no visible black hole or disk structure; the HUD reads 10 FPS and 300,000 particles
Claude Fable 5.1
A TDZ error blanked the page, and one round of feedback fixed it
A black hole in deep space with an orange-gold accretion disk in spiral bands, the event horizon at the centre pure black, structure clearly separated
GPT-6 Astra + Codex CLI
Same prompt, given an agent: Astra + Codex CLI screenshots itself and fixes it in three rounds
A black hole with a pure black centre, an accretion disk in spiral bands and two polar jets, one side brighter from Doppler beaming
Claude Fable 5.1 + Claude Code
Five rounds to bring mean luminance from 0.43 down to 0.10

three.js r170 is served from this site, so running a demo makes no third-party request. Published by the author as an individual; testing was self-funded and nothing here represents an employer's position.