Floating Ink

About this piece

Suminagashi means “floating ink”. It is one of the oldest forms of paper marbling, practised in Japan since at least the 12th century: ink is dropped onto still water, combed into patterns, then lifted off with a sheet of paper. Floating Ink is a free marbling simulator that does the same in your browser, with a real fluid simulation running on your graphics card: Japanese ink marbling, and paper marbling online, without the water or the mess.

How to play

• With Drop, tap to add a small drop of ink. Hold still to keep pouring and the drop grows.
• With Brush, drag to stir the water without adding ink. Comb rakes five lines at once.
• Pick a style for a different tray and inks. Click the selected ink again to change its colour.
• Press Use your hand to play with your webcam. Each finger you hold out stirs a line, a pinch pours ink, a fist lifts your hand off the water and, held over an ink, picks it, and a held thumbs-up pulls a print. Try them walks you through each one. The video stays on your device.
• Press Pull a print to lift what you made onto paper and keep it as a PNG.
• Keys: 1–4 pick an ink (1–8 in eight-ink mode), D, B and C pick a tool, [ and ] change its size, P pulls a print, Delete clears the tray.

What’s running

Every frame solves the Navier–Stokes equations on a grid: the water carries itself and the ink along, small eddies are kept alive, and a pressure solve keeps the water from compressing. Each new drop pushes the ink already on the water outward without losing any, which is what draws the rings. Pigments mix the way paint does, using Kubelka–Munk theory through Spectral.js, so blue stirred into yellow turns green. On WebGPU, up to two million metallic flecks ride the flow.

Want something like this?hello@pickurpage.com