How to get position of a threejs mesh using jsartoolkit?

Question

So I am using something like this to get the position of an object in my jsartoolkit threejs code:

            scene.updateMatrixWorld(true);
            var position = new THREE.Vector3();
            position.getPositionFromMatrix( selObj.matrixWorld );
            var oX = position.x;

Anyway, as I move my object with my marker, the vector value is not changing because the position is relative to the marker. So there should be a way to get the position of the object, otherwise collision detection is impossible...