zooming on cursor position on a THREE.js object
<p>Currently I am working on a THREE.js project and I am facing problem while zooming the object.It is zooming based on the center position of render while using trackball controls but I want to zoom based on the cursor position.I have tried disabling the zooming under trackball controls using <code>controls.noZoom=true</code> and wrote a code under mousewheel.It is quite good as i expected but it is zooming in only not zooming out.</p>

<pre><code>mousewheel = function (event) {
    event.preventDefault();
    event.stopPropagation();
            var factor = 15;
            var mX = (event.clientX / jQuery(container).width()) * 2 - 1;
            var mY = -(event.clientY / jQuery(container).height()) * 2 + 1;         
            var vector = new THREE.Vector3(mX, mY, 0.5);
            zoomstart = vector.unproject(camera);
            vector.sub(camera.position);
            camera.position.addVectors(camera.position, vector.setLength(factor));
            trackBallControls.target.addVectors(trackBallControls.target, vector.setLength(factor));
 };
</code></pre>

<p>Help me with this code to zoom based on mouse position.</p>