As of: 2026-10-08 23:45 CEST.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code). Human editor: Adam Bicz.
Canonical page: https://postcutoff.com/v/emollick-fable-5-1-drowned-towers-shader-x/

# Drowned neo-gothic towers twigl shader by Claude Fable 5.1, same prompt as for earlier models

Ethan Mollick (@emollick), 2 September 2026, X. 308,798 views as of 8 October 2026.
Kind: Made by AI.
Watch: https://x.com/emollick/status/2094983856424358023

## Why it is here

Mollick's running model comparison: 'The drowned neo-gothic tower twigl shader created by Fable 5.1 with the same prompt. (compare to Fable 5 in the quoted tweet, and other models before that)'. Found via claudevideo.org.

## Description (written by Gemini from the video)

**Summary**  
This video, shared by Ethan Mollick (@emollick), showcases a real-time GLSL shader generated by Anthropic's Claude Fable 5.1 using his benchmark prompt for "drowned neo-gothic towers." The resulting Twigl shader program renders a stormy, low-poly procedural sea submerging illuminated Gothic spires under falling rain and lightning.

**What is shown**  
- [00:00 - 00:04]: A dark, raymarched ocean scene with rolling swells, rain streaks, and dark silhouettes of Gothic spires with lit windows poking above the water under a moonlit sky.
- [00:05 - 00:07]: Flashes of lightning illuminate the overcast clouds and sharp spire architecture on the left horizon.
- [00:08 - 00:12]: Ongoing dynamic wave motion and rain particles, with another lightning flash visible in the stormy sky around [00:10].

**Claims & numbers**  
- None (silent screen capture recording of a shader execution without narration or text overlays).

**Notable quotes**  
- None.

**Assessment**  
This is a screen recording demonstrating the code generation capabilities of Claude Fable 5.1 executing a single-pass WebGL/Twigl fragment shader. The animation is rendered purely via procedural math and code without post-processing or video diffusion generation.

**Lyrics & themes**  
- Silent / no audio or lyrics. The visual theme explores a moody, gothic cataclysm, depicting forgotten grand architecture slowly swallowed by turbulent ocean waters.

**Lore & references**  
- **Mollick's Twigl Benchmark**: Ethan Mollick frequently evaluates the coding and spatial reasoning of successive frontier LLMs by asking them to write complex, compact GLSL shaders (such as "drowned neo-gothic towers" in Twigl format) without external assets.
- **Progressive Model Benchmarking**: Comparing how new models (like Claude Fable 5.1) handle volumetric lighting, raymarching, reflections, dynamic fluid movement, and particle effects directly in code compared to earlier generations.

**Visual style & craft**  
- **Render Style**: A compact procedural GLSL/Twigl fragment shader running in real time.
- **Craft**: Features signed distance functions (SDFs) and raymarching for the architectural spires, sinusoidal/procedural heightmaps for the water waves, dynamic alpha-blended rain streaks, emissive window lighting, and timed sky flashes simulating lightning. A desktop mouse pointer briefly appears on screen, indicating a live screen recording of a browser window.

_Described by gemini-3.8-flash on 2026-10-08 from the video's audio and frames._

## Made by AI

- Made with: Claude Fable 5.1
- How we know: X post (2026-09-02) states the shader was 'created by Fable 5.1 with the same prompt', quoting his Fable 5 prompt: 'create a visually interesting shader that can run in twigl-dot-app make it like an infinite city of neo-gothic towers partially drowned in a s[ea]…'.
- Human role: Same single prompt reused across models; Mollick recorded the result.
- Pipeline: Fable 5.1 → GLSL shader for twigl.app → screen recording
- Series: Model comparison benchmark

## Related

- 2026-09-01: [Anthropic releases Claude Fable 5.1 and Claude Mythos 5.1](https://postcutoff.com/e/2026-09-01-claude-fable-5-1-mythos-5-1/)

## People in it

- [Ethan Mollick](https://postcutoff.com/person/ethan-mollick/), Associate professor, Wharton School