https://github.com/w8r/greinerhormann

Greiner-Hormann polygon clipping algorithm. Does AND, OR, XOR. Plays nicely with Leaflet. Handles non-convex polygons and multiple clipping areas. ~3kb footprint, no dependencies
https://github.com/w8r/greinerhormann

algorithm computational-geometry leaflet polygon-clipping polygon-intersection polygon-union

Last synced: about 2 hours ago
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Greiner-Hormann polygon clipping algorithm. Does AND, OR, XOR. Plays nicely with Leaflet. Handles non-convex polygons and multiple clipping areas. ~3kb footprint, no dependencies

• Host: GitHub
• URL: https://github.com/w8r/greinerhormann
• Owner: w8r
• License: mit
• Created: 2014-08-01T12:59:28.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2023-04-15T21:28:20.000Z (over 1 year ago)
• Last Synced: 2024-11-02T09:07:34.253Z (16 days ago)
• Topics: algorithm, computational-geometry, leaflet, polygon-clipping, polygon-intersection, polygon-union
• Language: JavaScript
• Homepage: http://w8r.github.io/GreinerHormann/
• Size: 1.74 MB
• Stars: 239
• Watchers: 11
• Forks: 34
• Open Issues: 15
• Metadata Files:
  • Readme: README.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE

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README

        
[![License](http://img.shields.io/badge/license-MIT-brightgreen.svg)](http://opensource.org/licenses/MIT)

Greiner-Hormann polygon clipping

================================

 * Does AND, OR, difference (intersection, union, difference, if you're human)

 * Plays nicely with [Leaflet](http://github.com/leaflet/leaflet/), comes with an adaptor for it

 * Handles non-convex polygons and multiple clipping areas

 * ~3kb compressed, no dependencies

[Demo and documentation](http://w8r.github.io/GreinerHormann/)

**Note:** If you are looking for something more powerful, take a look at the [Martinez polygon clipping](https://github.com/w8r/martinez) implementation.

## Install

```bash

$ npm install greiner-hormann

```

Browserify

```js

var greinerHormann = require('greiner-hormann');

```

Browser

```html

```

## Use

```js

...

var intersection = greinerHormann.intersection(source, clip);

var union        = greinerHormann.union(source, clip);

var diff         = greinerHormann.diff(source, clip);

...

if(intersection){

    if(typeof intersection[0][0] === 'number'){ // single linear ring

        intersection = [intersection];

    }

    for(var i = 0, len = intersection.length; i < len; i++){

        L.polygon(intersection[i], {...}).addTo(map);

    }

}

```

## Format

Input and output can be `{x:x, y:y}` objects or `[x,y]` pairs. It will output the points in the same format you put in.