The algorithm is specifically fast and capable of working with polygons of all types: multipolygons (without cascading), polygons with holes, self-intersecting polygons and degenerate polygons with overlapping edges.
Play with it by forking this Codepen
import * as martinez from 'martinez-polygon-clipping';
const gj1 = { "type": "Feature", ..., "geometry": { "type": "Polygon", "coordinates": [ [ [x, y], ... ] ]};
const gj2 = { "type": "Feature", ..., "geometry": { "type": "MultiPolygon", "coordinates": [ [ [ [x, y], ...] ] ]};
const intersection = {
"type": "Feature",
"properties": { ... },
"geometry": {
"type": "Polygon",
"coordinates": martinez.intersection(gj1.geometry.coordinates, gj2.geometry.coordinates)
}
};.intersection(<Geometry>, <Geometry>) => <MultiPolygon>.union(<Geometry>, <Geometry>) => <MultiPolygon>.diff(<Geometry>, <Geometry>) => <MultiPolygon>.xor(<Geometry>, <Geometry>) => <MultiPolygon>
<Geometry> is GeoJSON 'Polygon' or 'MultiPolygon' coordinates structure.
The result is always 'MultiPolygon' coordinates, [] if it is empty. Its rings are closed and oriented as RFC 7946 requires: exterior rings counter-clockwise, holes clockwise.
<Operation> is an enum of { INTERSECTION: 0, UNION: 1, DIFFERENCE: 2, XOR: 3 } in case you have to decide programmatically
which operation do you need
Operations per second, higher is better. Run npm run bench to reproduce: it benchmarks the built bundle against JSTS, polygon-clipping and polyclip-ts (the engine behind @turf/union 7). All libraries produce the same result areas on these inputs.
| Benchmark | Martinez | JSTS 2.12 | polygon-clipping 0.15 | polyclip-ts 0.16 |
|---|---|---|---|---|
| Hole_Hole union (20 vertices) | 68,058 | 10,549 | 28,687 | 1,712 |
| Asia union (28k vertices) | 46.8 | 32.2 | 19.2 | 3.18 |
| States union (2.3k vertices) | 754 | 426 | 399 | 40.2 |
| Asia vs Asia shifted 0.05°: union | 16.2 | 5.29 | 6.06 | 0.97 |
| Asia vs Asia shifted 0.05°: difference | 16.0 | 5.25 | 5.11 | 0.72 |
Apple M3, Node 22.17. The "shifted" cases clip the Asia polygon against a copy of itself moved slightly east, so that nearly every edge intersects; demo/cases.html shows it with a slider for the shift.
The difference with a larger 0.3° shift, to make the slivers visible (the benchmark uses 0.05°).
The algorithm of Martinez et al. was extended to work with multipolygons without cascading.
npm run dev starts the demos:
demo/index.html: interactive map where you can edit the polygons.demo/cases.html: test case viewer. Pick any case fromtest/genericTestCasesortest/fixturesand an operation to see the inputs, the computed result and, for generic test cases, whether it matches the expected result. Use ←/→ to step through cases, keys 1–5 to switch the operation, and F to fit the view. The selection is kept in the URL, so a case can be linked, e.g.cases.html#generic%2Fissue155/xor.
- A new algorithm for computing Boolean operations on polygons (2008, 2013) by Francisco Martinez, Antonio Jesus Rueda, Francisco Ramon Feito (and its C++ code)
Other JavaScript implementations of the Martinez–Rueda–Feito algorithm:
- polygon-clipping by Mike Fogel was forked from this repository in February 2018 (see its license) and developed separately since. It snaps coordinates and intersection points to previously seen values within floating-point precision, and caps the sizes of its internal structures as a guard against infinite loops. (December 2023).
- polyclip-ts by Luiz Barboza is a TypeScript fork of
polygon-clipping, and so, indirectly, of this repository. It computes with arbitrary-precision
decimals (bignumber.js) and is the engine behind
@turf/unionand the other Turf 7 boolean operations.
See Benchmarks for how they compare in speed on the same inputs.
The MIT License (MIT)
Copyright (c) 2026 Alexander Milevski
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