js processing tree demo

gistfile1.txt

(function ($p) {

    var theta = 0;

    function setup() {
        $p.size(640, 360);
    }
    $p.setup = setup;

    function draw() {
        $p.background(0);
        $p.frameRate(30);
        $p.stroke(255);
        var a = ($p.mouseX / $p.width) * 90;
        theta = $p.radians(a);
        $p.translate($p.width / 2, $p.height);
        $p.line(0, 0, 0, -120);
        $p.translate(0, -120);
        branch(120);
    }
    $p.draw = draw;

    function branch(h) {
        h *= 0.66;
        if (h > 2) {
            $p.pushMatrix();
            $p.rotate(theta);
            $p.line(0, 0, 0, -h);
            $p.translate(0, -h);
            branch(h);
            $p.popMatrix();
            $p.pushMatrix();
            $p.rotate(-theta);
            $p.line(0, 0, 0, -h);
            $p.translate(0, -h);
            branch(h);
            $p.popMatrix();
        }
    }
    $p.branch = branch;
})