I'm having trouble grasping the execution of these code lines.
What does `project(camera)` do and what is the significance of `screenVector` in this context?
function labelBox(Ncardinal, radius, domElement)
{
this.screenVector = new THREE.Vector3(0, 0, 0);
this.position = convertlatlonToVec3(Ncardinal.lat,Ncardinal.lon).multiplyScalar(radius);
this.box = document.createElement('div');
a = document.createElement('a');
a.innerHTML = Ncardinal.name;
a.href ='http://www.google.de';
this.box.className = "spritelabel";
this.box.appendChild(a);
this.domElement = domElement;
this.domElement.appendChild(this.box);
}
labelBox.prototype.update = function()
{
this.screenVector.copy(this.position);
this.screenVector.project(camera);
var posx = Math.round((this.screenVector.x + 1)* this.domElement.offsetWidth/2);
var posy = Math.round((1 - this.screenVector.y)* this.domElement.offsetHeight/2);
var boundingRect = this.box.getBoundingClientRect();
//update the box overlays position
this.box.style.left = (posx - boundingRect.width) + 'px';
this.box.style.top = posy + 'px';
this.occludeLabel(this.box, this.marker);
};