var fleer = new Boid();
    fleer.userData.angle = 0;
    fleer.setBounds(canvas.width, canvas.height);
    fleer.maxSpeed = 2;
    fleer.position.x = canvas.width * Math.random();
    fleer.position.y = canvas.height * Math.random();
    fleer.velocity.x = 20 * Math.random() - 10;
    fleer.velocity.y = 20 * Math.random() - 10;

    var target = Boid.vec2(0, 0);

    canvas.addEventListener('mousemove', function(event) {
        var rect = canvas.getBoundingClientRect();
        target.x = event.clientX - rect.left;
        target.y = event.clientY - rect.top;
    });

    function update() {
        window.requestAnimationFrame(update);

        fleer.flee(target).update();
    }
    update();