lib/rotjs-library/manual/pages/noise.html

<h2>Noise generation</h2>

<div class="example">
var w = 256;
var h = 100;
var noise = new ROT.Noise.Simplex();

var display = new ROT.Display({width:w, height:h, fontSize:3});
SHOW(display.getContainer());

for (var j=0;j&lt;h;j++) {
	for (var i=0;i&lt;w;i++) {
		var val = noise.get(i/20, j/20) * 255;

		var r = ~~(val&gt;0 ? val : 0);
		var g = ~~(val&lt;0 ? -val : 0);
		display.draw(i, j, "", "", "rgb("+r+","+g+",0)");
	}
}
</div>

<div class="example">
var w = 120;
var h = 50;
var noise = new ROT.Noise.Simplex();

var display = new ROT.Display({width:w, height:h, fontSize:12, layout:"hex"});
SHOW(display.getContainer());

for (var j=0;j&lt;h;j++) {
    for (var i=j%2;i&lt;w;i+=2) {
        var val = noise.get(i/60, j/60) * 255;

        var r = ~~(val&gt;0 ? val : 0);
        var g = ~~(val&lt;0 ? -val : 0);
        display.draw(i, j, "", "", "rgb("+r+","+g+",0)");
    }
}
</div>