Scenes Volume II
Plate XV
Cloud paper
Abri · Deccani, from Persian: cloud paper, the marbled paper of Bijapur and Golconda
Drops of indigo, ochre, madder and grey-green are shaken onto a tray of thickened size, and each one spreads and pushes the others into rings. A stylus is drawn back and forth through them, the colours drift into clouds, and a sheet is laid on the surface and lifted off with the pattern on it. In playful, move through the size to marble it yourself before the paper goes down, or press Enter to drop a colour where your hand is.
Abri, cloud paper, was made in the Deccan courts of Bijapur and Golconda, where marbling came from Persia; the historical palettes here are indigo with ochre, madder with grey-green, ochre with lamp black, and indigo with madder.
The prompt
the prompt
Show a sheet of Deccani abri, the marbled paper of Bijapur and Golconda, being made, in canvas JavaScript with no image files. Look down into a wooden tray of cream size. From a seed, pick a restrained mineral palette of indigo, ochre, rose-madder and grey-green on cream, and let drops of colour land one after another; each drop spreads into a circle and pushes every earlier colour boundary outward, so repeated drops make rings. Keep the boundaries as crisp polygons and move their points, not pixels. Then draw a stylus back and forth through the colours: have it write velocity into a displacement field that eases off like thick liquid, and advect every boundary point through it. Let the size drift into soft clouds with a slow flow made from domain-warped noise, noise of noise, so the pattern veins and billows. Lay a sheet of paper on the surface from one edge, lift it and turn it over to show the print, mirrored as a real print is, with a deckle edge, paper grain and a few tiny air bubbles. Hold it, then start a new sheet. Let the viewer drag through the size to marble it themselves. Give it three registers: quiet is the lifted print as a finished still, warm makes sheet after sheet at an easier pace, and playful takes the viewer’s hand, from the pointer or the arrow keys, with Enter dropping a colour. Where the page lays its words over the tray, hold the size still under them and let no drop land there.
How the words become code
- each drop spreads into a circle and pushes every earlier colour boundary outward
- fieldsA drop of radius r moves every point p away from its centre c to c + (p − c)·√(1 + r²/‖p − c‖²). That formula keeps areas exact, so old drops become thin rings around new ones without any pixels being smeared.
- move their points, not pixels
- perceptual colourEvery colour is one closed polygon, painted oldest first. Because the marbling moves only the outlines, the edges stay sharp however far they are pulled.
- write velocity into a displacement field that eases off like thick liquid
- interactionThe stylus and your hand stamp their velocity into a coarse grid of 14-unit cells. The grid fades by e^(−4.2·dt) each step, and every boundary point is carried along by it, so the colours keep gliding for a moment after the stylus has passed. A key press counts as one stroke of a tenth of a second.
- a slow flow made from domain-warped noise, noise of noise
- smooth noiseNoise is sampled at coordinates that are themselves bent by noise, and the flow is taken as the curl of that field. A curl never piles colour up or thins it out, so the clouds swirl without losing paint.
- From a seed, pick a restrained mineral palette
- seedsThe seed chooses one of four historical colour pairings, where every drop lands, and whether the stylus combs straight passes, waves or a spiral. Each new sheet takes the next seed.
- a deckle edge, paper grain and a few tiny air bubbles
- paper and grainThe print is captured once into a layer, multiplied by painted paper, cut to a torn edge and dotted with pale specks where air was trapped under the sheet.
- hold the size still under them and let no drop land there
- calm zonesThe page reports where its text sits. Boundary points in those boxes, and within 30 units of them, are not carried by the stylus, the hand or the drift; drops aimed there never land, and the ripples and the stylus are not drawn there.
More of it
npx susegad add scene-abri