voronoi-scad

Voronoi patterns in OpenSCAD: rounded cells around sites you place or seed at random, for perforated panels, tiles and lattices. Each site gets the region closer to it than to any other site, pulled in from every neighbour so a web of even width runs between cells, with rounded corners.

Cells around 14 placed sites, each with its nucleus marked

A 2 mm panel perforated with a random pattern inside a frame

Use it

use <voronoi-scad/voronoi.scad>

// Cells around sites you choose
voronoi([[0, 0], [30, 0], [20, 10], [50, 20], [15, 30]], thickness = 1, round = 4);

// 40 random sites, the same pattern for the same seed
random_voronoi(n = 40, min = 0, max = 120, seed = 42, center = true);

// A polygon filled with a Voronoi web and a solid rim
voronoi_polygon([[0, 0], [60, 10], [80, 60], [30, 90], [-10, 50]], n = 30, edging = 3, seed = 7);

Each module draws 2D shapes; extrude them with linear_extrude() for a solid.

Module	What it draws
`voronoi(points, L, thickness, round, nuclei, nucleus_r)`	One cell per site. The web between two cells is `2 * thickness` wide and corners are rounded to `round`. `nuclei` punches a hole of `nucleus_r` at each site. `L` limits how far an outer cell reaches.
`random_voronoi(n, nuclei, L, thickness, round, min, max, seed, center)`	`voronoi()` over `n` random sites in `[min, max]` on both axes. The same `seed` gives the same pattern; with none, one is drawn and echoed. `center` moves the sites’ midpoint to the origin.
`voronoi_polygon(border, n, thickness, round, edging, seed)`	The polygon less a random pattern: the web, with a solid rim `edging` wide.

Function	Returns
`voronoi_cell(points, i, L, inset)`	Site `i`’s cell as a list of points, pulled in by `inset` from every neighbour, for use in your own geometry.
`random_points(n, lo, hi, seed)`	The random sites `random_voronoi()` uses.

Keep thickness and round in proportion to the sites’ spacing: a cell narrower than 2 * (thickness + round) vanishes. An outer cell has no neighbour beyond it, so it runs out to L; trim the pattern with intersection() or use voronoi_polygon() when the edge matters.

Random tiles trimmed to a square

Three outlines filled with Voronoi webs, two with rims

The module names and parameters follow Felipe Sanches’s OpenSCAD_Voronoi_Generator, and for the same calls this library draws the same cells, except that center now centres the sites’ midpoint. This is a separate implementation: it computes each cell as a polygon by clipping, which is about 9 times faster at 400 sites (0.73 s against 6.80 s on OpenSCAD 2026.10.15).

Checks

just test takes about 3 s on OpenSCAD 2026.10.15. It checks that:

every vertex of every cell of 40 random sites lies at least inset inside its bisector with every other site, and each site lies in its own cell;
the web between cells is 2 * thickness wide: cells grown by just under thickness stay apart, and grown by a little more, they meet;
a seed repeats its pattern and another changes it, and center moves the sites’ midpoint to the origin;
voronoi_polygon() stays inside its border and its rim is solid;
five fixed cases keep the volumes in tests/volumes.txt, which are the volumes OpenSCAD_Voronoi_Generator gives for the same calls;
every example evaluates without warnings, and a single site is refused.

just images renders the pictures.

Licence

MIT; see LICENSE.