Zentangle

A page cut into regions, each filled with a different line texture — a tangle.

What it is

Straight strokes divide the page; every region gets its own repeating pattern: hatching, scallops, pebbles, spirals, waves, bricks, or deliberate blank space. The appeal is the contrast between neighbouring textures, which is also the constraint — two dense tangles side by side read as one grey smear.

History

The Zentangle method was created by Rick Roberts and Maria Thomas in 2004 as a meditative drawing practice: small repeating patterns drawn without a plan, one region at a time. The generator makes the substrate — the partition and the texture choice — that a colourist or doodler then works over.

The implementation’s guarantees

• Regions cover the page exactly once, tested: the partition is convex half-plane clipping, and the areas must sum to the page or a tangle is leaking outside its region.
• No two regions in draw order share a tangle — the grey-smear failure, refused by construction and tested.
• Every tangle is drawn over its region’s bounding box and clipped by the scene’s group clip, which is what keeps the crate small: a texture never has to know the shape it fills.
• Stipple is excluded from the default palette, and that is a measurement, not taste: its dots come out at ~14 mm² against the adult colourability floor of 40 mm², and coarsening the pitch spreads them without growing them — a stipple dot is ink rather than a region to fill. It remains available by naming it in the spec, and such a page reports colorable: false honestly. A test pins this, so if it ever becomes colourable the doc gets corrected rather than quietly drifting.
• The escalation lever is a coarser pitch. Rating basis: none — a design.