earcut (Rust)

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

• Tracks the triangulation behavior and optional Delaunay refinement from the latest earcut 3.2.4.
• 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 (M4 Pro).

Polygon	earcut.hpp (C++)	earcut (Rust f64)
bad_hole	1.60 µs	1.21 µs
building	189 ns	95.5 ns
degenerate	93.9 ns	23.8 ns
dude	3.09 µs	2.82 µs
empty_square	188 ns	40.9 ns
water	135 µs	138 µs
water2	108 µs	102 µs
water3	8.73 µs	7.29 µs
water3b	843 ns	543 ns
water4	34.4 µs	36.9 µs
water_huge	834 µs	594 µs
water_huge2	1.80 ms	1.25 ms
water_huge3	18.1 ms	10.8 ms
MVT corpus	212 ms	175 ms

Public APIs: Rust reuses buffers; C++ allocates per call.

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).