Parametric crease-pattern families
Eight families generate from parameters rather than from a fixed library: Miura-ori by rows, columns and zigzag angle; Yoshimura diamonds and the waterbomb tessellation by rows and columns; the square twist by its twist angle; Kresling by polygon order, storeys and angle; the pleated hypar by rings and sides; a box-pleating grid by divisions with optional diagonals; and seven classic bases - preliminary, waterbomb, blintz, kite, fish, bird and frog.
Every crease is an ordinary SVG line, so a placed pattern can be restyled, recoloured and rearranged like any other artwork, and the sheet outline is drawn heavier than the creases the way crease patterns are conventionally printed.
Two published crease notations
Creases can be drawn in the colour convention crease-pattern designers read - mountain red, valley blue, sheet edge black - or in the Yoshizawa-Randlett notation printed origami books use, where the pattern is monochrome and a mountain fold is a chain line against a valley fold's dashes. A third setting applies both at once, so a pattern still distinguishes the two folds after a greyscale photocopy.
FOLD import and export
FOLD is the interchange format of the computational-origami community, and it is what ORIPA, Rabbit Ear and Origami Simulator read and write. Paste a .fold file and its vertices, edges and crease assignments render directly as editable shapes; a placed pattern can be saved back out as a .fold file for those tools.
The reader follows the spec where it is permissive and is strict where it is not: 3D coordinates are read and their z dropped because a crease pattern is flat, an unrecognised assignment letter degrades to unassigned so a file written against a later spec still opens, and an edge pointing at a vertex that does not exist is reported rather than drawn.
Flat-foldability reported, not assumed
Every generated or imported pattern is checked at each interior vertex against Maekawa's theorem, that mountains and valleys differ by exactly two, and Kawasaki's theorem, that alternating angles sum to 180 degrees. The readout names the first vertex that fails.
Those conditions are necessary but not sufficient, so the plugin reports that a pattern satisfies Maekawa and Kawasaki rather than claiming it folds flat. Patterns that genuinely do not fold flat say so: Kresling is a bistable buckling pattern and the pleated hypar cannot be folded with planar facets at all.
The folded form, computed rather than simulated
A pattern that folds flat can be drawn in its folded state as well as its unfolded one. There is no solver behind this: in a flat fold every crease turns through exactly 180 degrees, so each facet's folded position is a composition of reflections across the creases between it and a reference facet. That is exact arithmetic, and the fish, bird and frog bases fold into recognisable forms.
The folded view appears only where it is genuinely available. A pattern that does not fold flat has no folded state to draw, so for Kresling, the pleated hypar and an unassigned box-pleating grid the control is not offered at all rather than being shown unable to act.
Layer order is deliberately not claimed. Working out which facet lies above which is the hard half of flat-foldability, so folded facets are drawn translucent and allowed to accumulate: regions where more paper stacks read darker. That is an honest picture of layer density rather than a stacking order the plugin has not established.
Stays editable after placement
Placed patterns remember their settings. Select one and the plugin panel lets you change the family, its parameters or the notation and regenerate the pattern in place, with a single undo step restoring the previous version.