Given a three.js scene that is initialized on document ready, how can I add a 3D object (such as a simple cube), when the user triggers a click event after the init() function has already fired?

Here's a fiddle that already has the scene setup.

var camera, scene, renderer;

var geometry, material, mesh;



window.addEventListener(click, onClick, false);





function onClick() {

    alert(Replace me with code to add an object!);

}



var init = function () {



    renderer = new THREE.CanvasRenderer();

    renderer.setSize(window.innerWidth, window.innerHeight);

    document.body.appendChild(renderer.domElement);



    camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 1, 1000);

    camera.position.z = 500;



    scene = new THREE.Scene();



geometry = new THREE.CubeGeometry(200, 200, 200);

material = new THREE.MeshBasicMaterial({

                color: 0x000000,

                wireframe: true,

                wireframeLinewidth: 2

            });



mesh = new THREE.Mesh(geometry, material);

scene.add(mesh);



}



var animate = function () {



    requestAnimationFrame(animate);



    mesh.rotation.x = Date.now() * 0.0005;

    mesh.rotation.y = Date.now() * 0.001;



    renderer.render(scene, camera);



}



init();

animate();