adding click event listener for a cube in 3js

Question

In my code I have two cubes, I want to add click event listener to them. for example alerting on which cube the user clicked. When I added the click event listener to the document it was worked perfectly, but when I added the same click event listener to the cube it isn't showing anything. Here is my part of code..

<script type = "text/javascript" src = "three.min.js"></script>
<script type="text/javascript">
var camera = new THREE.PerspectiveCamera(70,window.innerWidth/window.innerHeight,0.1,1000);
var scene = new THREE.Scene();
var renderer = new THREE.WebGLRenderer();
renderer.setSize(window.innerWidth, window.innerHeight);

document.body.appendChild(renderer.domElement);
camera.position.z=30;

var geometry = new THREE.CubeGeometry(10,10,10);
var material = new THREE.MeshBasicMaterial({color:0x778899});
var cube = new THREE.Mesh(geometry,material);
cube.addEventListener("mousedown", onDocumentMouseDown, false);
cube.position.x = -10;
scene.add(cube);

var cube1 = new THREE.Mesh(geometry,material);
cube.addEventListener("mousedown", onDocumentMouseDown, false);
cube1.position.x=10;
scene.add(cube1);

var render = function(){
    var timer = Date.now()*-0.0002;
    requestAnimationFrame(render);
    camera.position.x = 30* Math.cos(timer);
    camera.position.z = 30* Math.sin(timer);

    camera.lookAt(scene.position);
    renderer.render(scene,camera);
};

render();

function onDocumentMouseDown(event){
    alert('hi');
}
</script>

Answer 1

addEventListener can only be used for DOM elements. See EventTarget.addEventListener()

If you want to select objects in a Three.js scene you should look into the Three.js Raycaster

The Raycaster basically sends a ray from the camera into the scene and returns an array of objects that intersect with the ray. To make use of the Raycaster you need to attach the addEventListener to the window object or your Three.js canvas.

For example: window.addEventListener( 'mousemove', onMouseMove, false );

There are a lot of examples for using the Raycaster on the Three.js examples page.