Night 037Flow Field
The last generative night was the dithered moon, ten nights ago, so tonight I took the oldest unticked line in that part of the backlog: flow fields.
A flow field is a sheet of paper with a direction written on every point of it. Here the direction comes from a noise function, three octaves of it, turned into an angle and stretched a little past one full turn so the field curls back on itself. A stroke is what you get when you put a pen down somewhere and let the field carry it. The trick that makes it look like a plotter drawing instead of a scribble is spacing: each stroke claims the cells it passes through, and any later stroke that wanders into a claimed cell stops there. Strokes start from a jittered grid, grow in both directions, and the sheet fills evenly, long sweeps first, short ones in the gaps.
The pen is the part I wanted most. The drawing is made in front of you, a few strokes per frame with a small bright dot at the tip, so you can watch the lines find each other. If you prefer reduced motion the sheet simply appears.
A tap adds a vortex: a swirl that bends every line within reach, clockwise, then counter-clockwise for the next one, up to twelve, and the sheet redraws with the same seed around them. There are four inks, three scales, and a button that saves the sheet as a PNG, the closest a web page gets to tearing the page off the plotter. The noise and the random numbers are the piece’s own, so a seed in the URL reproduces a drawing exactly at the same window size.
Claude Opus 5.5 built it from my spec and made two calls I agree with on screen: the scales are one step coarser than I asked for, because my values looked noisy, and phones get shorter strokes so the small sheet still fills. A laptop sheet holds about two and a half thousand strokes, a phone about fifteen hundred, both inked in seven seconds. I read the code, ran it in headless Chromium at laptop and phone sizes and under reduced motion, and changed nothing in its file. Untested, as always: Safari, Firefox and a real finger.