Marks on the sliders are the best-looking settings. A slider holds there for a moment; keep sliding to go between them.
The Groove runs the Gray-Scott model: two imaginary chemicals, A and B, spread across the screen and follow four rules.
That last rule is the trick. B grows where it already is but uses up the A around it, and A floods back in from the sides faster than B can follow. So B can't take over; it settles into bands, spots, or rings with A in between. Nobody draws the pattern. Small changes to feed and kill change which one you get.
Piano: the eight white keys, F up to the next F, are the eight looks in order, and each black key lands halfway between its two neighbors. Playing a key glides the sliders to its look, plays its note, and moves the whole song to match without changing its speed. B, in the middle, is the song as recorded. Each key to the right moves the song up a half step, and each key to the left moves it down one, up to six either way. The note you play moves with the song, so it always fits.
Moving the key: about 45 times a second, a slice of the song is split into some 2,000 pure tones, each tone is retuned, and the slices are joined back up (a phase vocoder). It sounds best near B; at the far ends, drums soften a little and the sound can smear.
Sound (off until you tap sound or a key): "Cinematic Rise" by Adam Gurley, made with Suno, an AI music tool, playing on a loop. The song (about 3 MB) loads only when you turn sound on. While it plays, the stripes dance: the bass makes their edges quiver, and every drum hit swells and shakes them and gives the drift a push. The hits were mapped from the song ahead of time, so each one lands when you hear it (allowing for the key shifter's delay and your device's sound delay).
Sliders and keys at the top of this panel fold each part away. Hide clears every control so you can just watch and draw; show, or the Esc key, brings them back.
Peter Gray and Stephen Scott described these reactions in the 1980s, and John Pearson mapped their many patterns in 1993. They are Turing patterns, after Alan Turing's 1952 idea that markings like a zebra's stripes could form this way. This is a simulation of the rules, not real chemicals; the color bands and the drift are added for looks.
This experiment needs a browser with WebGL 2.