Reaction-diffusion · deepseek-v4-flash-0731
Run a Gray-Scott reaction-diffusion simulation on a canvas that grows organic Turing patterns in real time, with the mouse seeding new growth.
transcript · 6 messages
Run a Gray-Scott reaction-diffusion simulation on a canvas that grows organic Turing patterns in real time, with the mouse seeding new growth.
thinking
The user wants a single-page web app with Gray-Scott reaction-diffusion simulation on canvas, with mouse seeding new growth. Let me build index.html with everything inline. Let me create a comprehensive implementation of Gray-Scott reaction diffusion. Let me write the file.
/workspace/index.html (14590 bytes)Successfully wrote 14590 bytes to /workspace/index.html
thinking
Let me review the step function. There's a bug in my swap logic. Let me trace through. Initial state: - a = buffer0, b = buffer1 - write loop uses A=a (buffer0) to read, writes to B=b (buffer1). Good. - After writing, I wrote: `a = B; b = A;` — so a becomes buffer1 (which has new data), b becomes buffer0 (old). Next call: A=a=buffer1 reads new data, writes to B=buffer0. Good, that works. The `const tmp` line is unused but harmless. Actually there's a subtle issue: I declared `let A = a; let B = b;` — no wait, I used `const A = a, B = b;`. Then after `a = B; b = A;` it's consistent. Good. Actually wait — but inside step I read from A and write to B. Since B is a separate buffer, no race. Fine. Let me double check the seeding: seeds V and reduces U. Good for Gray-Scott. The simulation with dt fixed 0.2 per step and STEPS up to 20. That should give decent speed. One concern: full render on every frame repaints 1024x768... could be heavy but acceptable. Let me quickly sanity check the file is valid by checking with node? Actually it's browser JS. Let me just verify syntax via node --check. Also there's unused variable `bTyped` — fine. Let me verify the swap carefully once more since it's critical. Actually there is a subtle bug: `let bTyped = B;` and then later `bTyped[c]=...`. But I also reassign `a=B; b=A;` at the end. bTyped not used again. Fine. Let me run node --check but it has DOM refs at top level (inside IIFE but referencing document at end). node --check only parses syntax, doesn't execute. Good. Let me check.
{"command":"cd /workspace && node --check index.html 2>&1 | head; echo \"---extract script---\"; node -e \"const s=require('fs').readFileSynnode:internal/modules/esm/get_format:236 throw new ERR_UNKNOWN_FILE_EXTENSION(ext, filepath); ^ TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".html" for /workspace/index.html at Object.getFileProtocolModuleFormat [as file:] (node:internal/modules/esm/get_format:236:9) at defaultGetFormat (node:internal/modules/esm/get_format:262:36) at checkSyntax (node:internal/main/check_syntax:67:20) { code: 'ERR_UNKNOWN_FILE_EXTENSION' } ---extract script--- JS OK -rw-r--r-- 1 node node 14607 Aug 1 05:17 index.html
thinking
The JS extracted and passed syntax check. Good. Let me verify the script extraction / closing tags work. The regex matched one script; there's only one script tag so fine. Let me double-check there's no issue with the regex matching — it matched and JS OK. Everything is in place. The file is complete and self-contained.
The app is built and the embedded JavaScript passes a syntax check. ## What I built — `/workspace/index.html` A fully self-contained single-file Gray–Scott reaction–diffusion app (no external resources, all CSS/JS inline): **Core simulation** - Classic Gray–Scott two-species model (`Du=1.0, Dv=0.5`) with a 4-neighbour Laplacian, solved on a `Float64Array` field. Two buffers are ping-ponged to stay write-safe. - Fixed timestep accumulation with a `requestAnimationFrame` loop, JIT-batched *steps-per-frame* so it runs smoothly in real time. **Organic growth & mouse seeding** - <kbd>Drag/click</kbd> (or touch) injects a blob of low-`U`/high-`V` that grows into a Turing pattern; while dragging, the seed wanders with jitter, laying down a tendril of growth literally as you draw. - Light "hover seeding" too, so patterns keep creeping under your cursor even without a click. **Tuning & presets** - Direct `f` / `k` number inputs plus six curated parameter presets (Coral, Maze, Bubbles, Coral wall, Finger, Solitons). - Brush-size and simulation-speed sliders. - Clear and Pause/Resume controls. **Rendering** - A warm coral→amber→cream palette baked into a 1024-entry LUT, mapped from `V` concentration and blitted via `putImageData` for speed. - Auto-resizes with the window and respects devicePixelRatio. - Glassmorphism out-of-canvas UI with a live status readout. The canvas is hardware-DPR aware and the sim loops continuously, so patterns keep organically expanding on their own between your seeds.
TAKE IT TO CODE
A single self-contained HTML file — copy it and open in any browser, or reuse the prompt with your own pi-agent run.
RUN
EVALUATION
Gray-Scott simulation seeds Turing patterns on drag but click/idle/keyboard produce no visible change; patterns look plausible.
Vision grade · anthropic/claude-sonnet-5
MEASUREMENTS
Raw readings from the capture, not a verdict — the grade above is the only judgement. Percentages are how much of the screen changed; the measure under-reports sparse motion on a dark background.