srpg generates simply-connected and multiply-connected polygons by means of a regular grid (with quadratic cells).
Source code is available on github.
See the srpg* directories in /db/wip/polygons/random/ for polygons and /db/wip/polygons-with-holes/random/ for polygons with holes.
There are several variants:
srpg_iso: orthogonal polygons.srpg_iso_aligned: orthogonal polygons on an integer grid.srpg_octa: octagonal polygons.srpg_perturbed: random polygons.srpg_perturbed_smo: random polygons with smoothed corners.srpg_perturbed_smr: random polygons with even smoother corners.
srpg0000051
srpg_iso0000039
srpg_octa0000035
srpg_smo0000123
srpg_mc0000166
srpg_iso_aligned_mc0000150