Ink dropped into water, blooming on paper, in the manner of sumi-e. Each bloom appears, spreads quickly and then more slowly, its ragged edge darker where the pigment gathers, and fades as it thins to a pale wash. Eight blooms come and go at their own times, slow currents bend their edges, and the paper has the warm tone, faint mottle and long fibres of washi.

The paper, ink and wash colours, ink amount, bloom size, edge raggedness and paper fibre are all settings. The demo has presets for sumi, indigo, sepia, shu red and a night version with pale ink on dark paper, plus a large, slow look and a Behind text preset.

Made for calligraphy and tea studios, galleries, restaurants, wellness and Japanese-inspired brands, book and poetry sites, stream backgrounds and video. Its reduced-motion setting holds every bloom still as it is on the poster frame for visitors who ask for less motion, and a veil setting thins the ink so text reads on top. At the Behind text preset, dark text keeps a contrast ratio of at least 10.4:1 against 98 % of the background under it.

What you get: a GLSL ES 3.00 fragment shader for plain WebGL2, an ES module that returns a three.js ShaderMaterial, a Shadertoy version, an offline demo page with a settings panel, a 10-second 1920 x 1080 H.264 loop that plays end to start without a seam, the same loop upright at 1080 x 1920 for vertical video, and the poster frame as a PNG (and a WebP for the web). One pass with no textures, about 2.3 ms of GPU time per 1920 x 1080 frame on a recent laptop, measured in headless Chromium. The README covers set-up, reduced motion, every uniform and performance notes.