Gray-Scott

Real-time Gray-Scott reaction-diffusion patterns — 100% GPU via WebGPU compute, in your browser.

Run it

uv run uvicorn server:app --reload --port 8002

Open http://localhost:8002 in Chrome 113+ (WebGPU required).

Using Gray-Scott

• 12 presets — spots, solitons, worms, mazes, holes, chaos, waves, U-Skate, and more from Pearson's (F, k) phase diagram.
• Brush painting — click and drag on the field to seed activator V; brush radius 1–20 cells.
• Live parameters — F (0.01–0.08) and k (0.03–0.07) sliders, with J/K and H/L keyboard nudges.
• Speed — 1–64 substeps per frame (default 16).
• Resolution — 256 / 512 / 1024 cells (default 512).
• First visit opens an 11-step onboarding tour; replay it anytime via Replay the Tour in the guide.
• The ? button opens the in-app guide — the full user manual.

Key	Action
P	Play / pause
M	Step one frame while paused
R	Reset to current preset
C	Clear field
J / K	Decrease / increase F by 0.001
H / L	Decrease / increase k by 0.0001

Understanding & hacking Gray-Scott

• docs/architecture.md — system + module map
• docs/numerical-methods.md — FTCS scheme + stability
• docs/reaction-diffusion.md — equations + pattern regimes
• docs/README.md — full annotated index
• DEPLOYMENT.md — Coolify / Docker deploy + Umami analytics wiring

Numbers

Verified against code:

• 12 presets in static/js/presets.js
• 11-step tour in static/js/tour.js
• 1–64 substeps/frame, default 16
• 256 / 512 / 1024 grid resolution, default 512
• Du = 0.2097, Dv = 0.105, dt = 1.0
• Stability ceiling dt ≤ 1/(4·Du) ≈ 1.19
• Single WGSL compute shader, 8×8 workgroups, four storage buffers ping-pong

Develop

• npm test — 33/33 Playwright; headed, port 8321, --enable-unsafe-webgpu
• No build step — vanilla ES modules
• Dockerfile + DEPLOYMENT.md for shipping