var projector = new THREE.Projector();  

 var world_vector = new THREE.Vector3(0,0,1);  

 var vector = projector.projectVector(world_vector, camera);  

 var halfWidth = window.innerWidth / 2;

 var halfHeight = window.innerHeight / 2;  

 var result = {  

     x: Math.round(vector.x * halfWidth + halfWidth),

     y: Math.round(-vector.y * halfHeight + halfHeight)  

 };