Two imaginary chemicals, U and V, spread through the grid. V is made from U and removed again, U is fed in at a steady rate, and both diffuse, V more slowly. From a few seeds of V, spots, stripes and mazes grow and settle, the way animal coat patterns and coral are thought to form. Dark blue shows where V is. Choose a pattern, or move the feed and kill sliders (they are the two numbers that decide what grows), and press Play; it needs a few thousand steps. Click or drag to add more V.

This is the Gray-Scott model, a continuous cousin of the cellular automata on the other pages: every cell holds two real numbers, updated from its four neighbors, and the grid wraps around. The five presets are settings I tried in a quick test of my own, each of which grows a clear pattern from random seeds; they are not named in the literature the way I have named them. Most feed and kill values grow nothing at all (the blue slowly dies out), and the patterns sit in a narrow band, so move the sliders in small steps. The Steps per frame slider trades speed for smoothness.

This page was created with Claude Code.