About

The fastest and smallest JavaScript polygon triangulation library with builtin tesselation. 3.18 kB minified and gzipped.

Install

# NPM
npm install earcut
# PNPM
pnpm add earcut
# Yarn
yarn add earcut
# Bun
bun add earcut

The Algorithm

The library implements a modified ear slicing algorithm, optimized by z-order curve hashing and extended to handle holes, twisted polygons, degeneracies and self-intersections in a way that doesn't guarantee correctness of triangulation, but attempts to always produce acceptable results for practical data.

It's based on ideas from FIST: Fast Industrial-Strength Triangulation of Polygons by Martin Held and Triangulation by Ear Clipping by David Eberly.

Usage

import { earclip } from 'earclip'

const poly = [[[3506,-2048],[7464,402],[-2048,2685],[-2048,-2048],[3506,-2048]],[[-2048,-37],[1235,747],[338,-1464],[-116,-1188],[-2048,-381],[-2048,-37]],[[-1491,-1981],[-1300,-1800],[-1155,-1981],[-1491,-1981]]]
const modulo = 8192 / 2

const res = earclip(poly, modulo)
console.log(res)

const polyAsPoints = [
    [{ x: 3506, y: -2048 },{ x: 7464, y: 402 },{ x: -2048, y: 2685 },{ x: -2048, y: -2048 },{ 3506, y: -2048 }],
    [{ x: -2048, y: -37 },{ x: 1235, y: 747 },{ x: 338, y: -1464 },{ x: -116, y: -1188 },{ x: -2048, y: -381 },{ x: -2048, y: -37 }],
    [{ x: -1491, y: -1981 },{ x: -1300, y: -1800 },{ x: -1155, y: -1981 },{ x: -1491, y: -1981 }],
]
const res2 = earclip(polyAsPoints, modulo)

assert(res === res2)

Development

Requirements

You need the tool tarpaulin to generate the coverage report. Install it using the following command:

cargo install cargo-tarpaulin

The bacon coverage tool is used to generate the coverage report. To utilize the pycobertura package for a prettier coverage report, install it using the following command:

pip install pycobertura

Running Tests

To run the tests, use the following command:

# TYPESCRIPT
## basic test
bun run test
## live testing
bun run test:dev

# RUST
## basic test
cargo test
# live testing
bacon test

Generating Coverage Report

To generate the coverage report, use the following command:

cargo tarpaulin
# bacon
bacon coverage # or type `l` inside the tool

Benchmarks

Rust

Run the Rust benchmarks using the following command:

cargo +nightly bench