Sine waves

function onGLC(glc) {
    glc.loop();
    glc.size(500, 500);
    glc.setDuration(4);
    glc.setMode('single');
    glc.setEasing(false);
    var list = glc.renderList,
        width = glc.w,
        height = glc.h,
        color = glc.color;

    glc.styles.backgroundColor = "rgb(21, 21, 21)";

    // your code goes here:

    var mag = width/12;

    for(var n=0; n<4; n++){
        wave(width/4 + 2*n*mag, mag, n*Math.PI/2);
    }

    function wave (ypos, mag, phase){

        for(var i=50; i<=width-50; i+=10){
            if(parseInt((i-50)/10)%2 == 1){
                glc.styles.fillStyle = "#ff0000";
            } else {
                glc.styles.fillStyle = "#0000ff";
            }

            list.addCircle({
                index: i,
                x: function(t){
                    var offset = t*3*Math.PI;
                    return ypos + mag*Math.sin(Math.PI*this.index/300 + offset + phase);
                },
                y: i,
                radius: 3,
                fillStyle: (((i-50)/10)%2 == 0)?"#cc0000":"#fff"
            });
            list.addCircle({
                index: i,
                x: function(t){
                    var offset = t*3*Math.PI;
                    return ypos + mag*Math.sin(-Math.PI*this.index/300 - offset - phase);
                },
                y: i,
                radius: 3,
                fillStyle: (((i-50)/10)%2 == 0)?"#cc0000":"#fff"
            });
        }
    }
}