Converting basic processing sketch by Daniel Shiffman to work with the plask JavaScript framework

Additive Wave

/**
 * Additive Wave
 * by Daniel Shiffman.
 *
 * Create a more complex wave by adding two waves together.
 */
var plask = require('plask');

var xspacing = 8;   // How far apart should each horizontal location be spaced
var w;              // Width of entire wave
var maxwaves = 4;   // total # of waves to add together

var theta = 0.0;
var amplitude = [];   // Height of wave
var dx = [];          // Value for incrementing X, to be calculated as a function of period and xspacing
var yvalues = [];

plask.simpleWindow({
    width: 500,
    height: 400,
    init:function() {
        var canvas = this.canvas, paint = this.paint;
        this.framerate(30);
        paint.setStyle(paint.kFillStyle);
        paint.setFlags(paint.kAntiAliasFlag);
        paint.setColor(80, 0, 0, 50);

        w = 400 + 16;
        yvalues = new Array(w / xspacing);

        for (var i = 0; i < maxwaves; i++) {
            amplitude[i] = random(10, 30);
            period = random(100, 300); // How many pixels before the wave repeats
            dx[i] = (plask.k2PI / period) * xspacing;
        }
    },
    draw:function() {
        var canvas = this.canvas, paint = this.paint;
        canvas.drawColor(255, 255, 255, 255);
        this.calcWave();

        for (var i = 0; i < yvalues.length; i++) {
            canvas.drawCircle(paint, i * xspacing, 200 + yvalues[i], 16);

        }
    },
    calcWave: function() {
        theta += 0.02;

        // Set all height values to zero
        for (var i = 0; i < yvalues.length; i++) {
            yvalues[i] = 0;
        }

        // Accumulate wave height values
        for (var j = 0; j < maxwaves; j++) {
            var x = theta;
            for (var i = 0; i < yvalues.length; i++) {
                // Every other wave is cosine instead of sine

                yvalues[i] += Math[j % 2 ? 'sin' : 'cos'](x) * amplitude[j];

                x += dx[j];
            }
        }
    }
});

function random(min, max) {
    return min + Math.random() * (max - min)
}