circle-regions

Circle Intersection Regions

Important Note

Please be advised this library is in the process of a complete rewrite, which will be released during October–November 2020. The new 1.x tier will deprecate everything in the 0.x tier. Version 1.x will bring a completely new approach, which is even more efficient, more robust, and natively allows for tangent circles – the new version will set new state of the art benchmarks for performance.

Overview

A blazingly fast solution for computing all regions in a 2D plane resulted from intersecting any number of circles, in any configuration. This is essentially the engine inside Harrison Hogg's wonderful "circles" art project – check it out live here; the algorithm is described on HHogg's website. I also saved the algorithm description on the Wayback Machine, in case he decides to drop it off the website for some reason.

Installation

The library works both in NodeJS, and as a stand-alone, browser library (use the browser approach below to test it on Runkit).

NodeJS

Install it with

npm install circle-regions

And use it

"use strict";
const circleRegions = require('circle-regions');

console.log(circleRegions.getIntersectionRegions([
  {
    x: 0,
    y: 0,
    radius: 1
  },
  {
    x: 0.5,
    y:0.5,
    radius: 1
  }
]));

Typescript is also supported; the definitions are bundled with the npm package.

Browser

Generate the JavaScript bundle

npm run browserify

This will produce a plain JavaScript file called circle-regions.Bundle.js, which you can load in your HTML file. You can then use it

console.log(circleRegions.getIntersectionRegions([
  {
    x: 0,
    y: 0,
    radius: 1
  },
  {
    x: 0.5,
    y:0.5,
    radius: 1
  }
]));