Вращение вокруг точки (pivot) нарисованной с помощью Three.js линии

var container, stats;
var camera, scene, renderer, objects;
var line;
 
 
init();
animate();
function init() {
  
    camera = new THREE.PerspectiveCamera(75, 500 / 500, 1, 10000);
    camera.position.z = 50;
    scene = new THREE.Scene();
    var spotLight = new THREE.SpotLight( 0xffffff );
    spotLight.position.set( 0, 0, 100 );
    scene.add(spotLight );
 
 
    var geometry = new THREE.Geometry();
    geometry.vertices.push(
        new THREE.Vector3( 1.7, -9, 15 ),
        new THREE.Vector3( 1.7, 21, 15 )
    );
   
    line = new THREE.Line( geometry, new THREE.LineBasicMaterial( { color: 0x000000, opacity: 0.5 } ) );
 
    scene.add( line );
    //scene.add( new THREE.AmbientLight( 0x111111 ) );
    renderer = new THREE.WebGLRenderer({antialias: true});
    renderer.setSize( 500, 500 );
    renderer.setClearColor( 0xffffff, 1);
    container.appendChild( renderer.domElement );
 
    stats = new Stats();
    stats.domElement.style.position = 'absolute';
    stats.domElement.style.top = '0px';
    container.appendChild( stats.domElement );
 
  
}
 
 
function animate() {
    requestAnimationFrame( animate );
    render();
    stats.update();
}
function render() {
    line.rotateZ(0.001);
    renderer.render( scene, camera );
}