Awesome

island.js

Island map generator in JavaScript, using a Voronoi graph and perlin noise http://lebesnec.github.io/island.js

• Inspired by http://www-cs-students.stanford.edu/~amitp/game-programming/polygon-map-generation/
• Use paper.js for rendering : http://paperjs.org/
• Use Raymond Hill Voronoi implementation : https://github.com/gorhill/Javascript-Voronoi
• Use Sean McCullough perlin noise generator : https://gist.github.com/banksean/304522#file-perlin-noise-simplex-js

Usage :

<canvas id="island" resize="true"/></canvas>
<canvas id="perlin" hidden="true"></canvas>
<script type="application/javascript">
    paper.install(window);
    window.onload = function(e) {
        paper.setup('island');
        Island.init();
    };
</script>

You can also set the following optionals parameters :

Island.init({
    width: 500,
    height: 500,
    perlinWidth: 256,
    perlinHeight: 256,
    allowDebug: false, // if set to true, you can click on the map to enter "debug" mode. Warning : debug mode is slow to initialize, set to false for faster rendering.
    nbSites: 10000, // numbers of voronoi cell
    sitesDistribution: 'hexagon', // distribution of the site of the voronoi graph : random, square or hexagon
    sitesRandomisation: 80, // will move each site in a random way (in %), for the square or hexagon distribution to look more random
    nbGraphRelaxation: 0, // nb of time we apply the relaxation algo to the voronoi graph (slow !), for the random distribution to look less random
    cliffsThreshold: 0.15,
    lakesThreshold: 0.005, // lake elevation will increase by this value (* the river size) when a new river end inside
    nbRivers: (10000 / 200),
    maxRiversSize: 4,
    shading: 0.35,
    shadeOcean: true
});

Demo :

Here : http://lebesnec.github.io/island.js/

Sample :

Rendering with 50000 polygons and 250 rivers :

With 10000 polygons, shading off :

Rendering using a "square" graph :