konrad-g/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

Greiner-Hormann polygon clipping

• Does AND, OR, XOR (intersection, union, difference, if you're human)
• Plays nicely with Leaflet, comes with an adaptor for it
• Handles non-convex polygons and multiple clipping areas
• ~3kb compressed, no dependencies

Demo and documentation

Note: If you are looking for something more powerful, take a look at the Martinez polygon clipping implementation.

Install

$ npm install greiner-hormann

Browserify

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

Browser

<script src="path/to/greiner-hormann(.leaflet).min.js"></script>

Use

...
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.