var h1;
var h2;

function HLine(y, s) {
    this.ypos = y;
    this.speed = s;
}

HLine.prototype.update = function() {
    this.ypos += this.speed;
    if (this.ypos > height) {
        this.ypos = 0;
    }
    line(0, this.ypos, width, this.ypos);
}

function setup() {
    createCanvas(100, 100);
    h1 = new HLine(20, 2.0);
    h2 = new HLine(50, 2.5);
}

function draw() {
    background(204);
    h1.update();
    h2.update();
}