# Reaction–Diffusion (反応拡散パターン)

> Reaction-diffusion simulation lets substances react locally while spreading at different rates, self-organizing small disturbances into spots, stripes, mazes and coral-like patterns.

- IndexStyle No.590 — https://indexstyle.org/styles/reaction-diffusion
- Kind: Technique · Family: Computational Expression · Era: 1952–
- Mood: Futurity, Technique, Exhilaration
- What this family collects: Forms grown from small rule sets and iteration into structures that could not be drawn one mark at a time, where rules, initial state and time determine the look.

## Defining characteristics

- Round spots dividing at even distances
- Continuous curving maze stripes
- Coral or cellular boundaries branching from edges
- Self-organized marks of nearly constant thickness

## Best used for

- Explaining biological spot and stripe formation in research, education and exhibitions
- Growing organic surface, motion and type patterns

## Composition recipe

- Typography & lettering: Place copy in low-density regions instead of eroding every letter with the pattern.
- Layout & structure: Show growth from a seed or boundary condition rather than freezing a uniform all-over print.
- Material & texture: Set reaction terms, diffusion rates, feed and kill rates, then iterate from a small perturbation.

## Colour

Read off the reference works below, so a direction rather than a fixed palette.

- Ground: #F4E56B
- The colour it is remembered by: #38C6A3
- Text and outlines: #101B2E

## What to avoid

A hand-drawn animal print is not reaction-diffusion. Time and parameter changes must remain visible in the pattern.

## Application checklist

Work through this before calling a piece an application of this style.

- [ ] Visible in the piece: Round spots dividing at even distances
- [ ] Visible in the piece: Continuous curving maze stripes
- [ ] Visible in the piece: Coral or cellular boundaries branching from edges
- [ ] Visible in the piece: Self-organized marks of nearly constant thickness
- [ ] The layout follows: Show growth from a seed or boundary condition rather than freezing a uniform all-over print.
- [ ] The lettering follows: Place copy in low-density regions instead of eroding every letter with the pattern.
- [ ] The material and surface follow: Set reaction terms, diffusion rates, feed and kill rates, then iterate from a small perturbation.
- [ ] The colour relation holds: #F4E56B as ground, #38C6A3 carrying the style, #101B2E for text and outlines
- [ ] At least one reference work below has been studied directly
- [ ] The caution above ("What to avoid") has been addressed

## Related styles

- **Generative Art (ジェネラティブアート)** — A way of working in which the maker writes only the rule and the randomness, leaving the drawing to the machine. As in Nees's plotter work, the result is shown as several variants born of one rule. → https://indexstyle.org/styles/generative-art
- **L-system Graphics (L-systemグラフィックス)** — L-system graphics rewrite symbol strings in parallel and interpret them as drawing, turning a few rules into recursively growing plants, trees, mycelia and ornaments. → https://indexstyle.org/styles/l-system-graphics

## Compose it with something else

The dictionary can put this entry in a structural role and another in an accent role, and report where the two fight: https://indexstyle.org/compose?ids=reaction-diffusion+generative-art

## Further study

- Turing patterns
- Gray-Scott model
- Activator-inhibitor systems

## Reference works

- Royal Society — A. M. Turing, The Chemical Basis of Morphogenesis — https://royalsocietypublishing.org/doi/10.1098/rstb.1952.0012

## AI interpretation

An AI-generated interpretation image exists for browsing convenience only — it is not a reference work: https://indexstyle.org/ai/reaction-diffusion.jpg

## Source of record

- Royal Society — A. M. Turing, The Chemical Basis of Morphogenesis — https://royalsocietypublishing.org/doi/10.1098/rstb.1952.0012

## Machine surfaces

- JSON: https://indexstyle.org/api/styles/reaction-diffusion
- Image-generation prompt (legally clean): https://indexstyle.org/styles/reaction-diffusion/prompt.txt
- MCP: https://indexstyle.org/mcp (tools: search_styles, get_style, compare_styles, compose_styles, find_related_styles; prompts: image-prompt, apply-style)