earcut (Rust)

A Rust port of the mapbox/earcut polygon triangulation library.

• Tracks the triangulation behavior and optional Delaunay refinement from the latest earcut 3.2.3.
• Designed to avoid unnecessary memory allocations. Internal buffers and the output index vector can be reused across multiple triangulations.
• Also provides earcut::int::EarcutI32 for integer coordinates with exact integer predicates, but it can be slower than the float-based Earcut on modern CPUs.
• An additional helper, utils3d::project3d_to_2d, projects coplanar 3D polygons onto a 2D plane for use with earcut.

Benchmarks

Time per iteration (smaller is better). Measured on a MacBook Pro (M1 Pro).

Polygon	earcut.hpp (C++)	earcut (Rust)
bad_hole	2.27 µs/i	2.337 µs/i
building	294 ns/i	167.7 ns/i
degenerate	139 ns/i	42.63 ns/i
dude	4.46 µs/i	4.275 µs/i
empty_square	271 ns/i	83.22 ns/i
water	284 µs/i	236.2 µs/i
water2	192 µs/i	155.7 µs/i
water3	12.8 µs/i	13.78 µs/i
water3b	1.26 µs/i	1.060 µs/i
water4	53.6 µs/i	58.69 µs/i
water_huge	1.399 ms/i	1.298 ms/i
water_huge2	2.694 ms/i	2.511 ms/i
water_huge3	21.84 ms/i	19.50 ms/i
MVT corpus	250 ms/i	248 ms/i

Demo

A simple egui-based visualizer for inspecting how earcut works.

cargo run --example visualizer

License

Licensed under either the MIT License (LICENSE-MIT) or the Apache License 2.0 (LICENSE-APACHE) at your option.

This project contains portions derived from mapbox/earcut, originally distributed under the ISC License (LICENSE-ISC).