title: Selecting vertices that are visible from a particular position
body: <p>how to determine which vertices of buffer geometry are visible from a particular position in the scene?
  I am using Autodesk view and data api and raytracing doesn’t seem to work.
  The purpose is to apply functions to only parts of 3D objects that is visible to viewpoints/vectors located along a line.</p>
  
  <p>Any help is appreciated</p>
  
  <p>bellow is code sample:</p>
  
  <pre><code>var origin = new THREE.Vector3(1, 2, 3);
              var direction = new THREE.Vector3(3, 4, 7);
              var sphereMaterial = new THREE.MeshPhongMaterial({ color: 0xff0000 });
              sphereMaterial.side = THREE.DoubleSide; 
              viewer.impl.matman().addMaterial('adn-material-vertex', sphereMaterial,true);
              var directionSphere = new THREE.Mesh(new THREE.SphereGeometry(2, 20), sphereMaterial);
              viewer.impl.scene.updateMatrixWorld();
              var raycaster = new THREE.Raycaster(origin, direction.normalize());
              var intersect = raycaster.intersectObject(directionSphere, true);
               console.log("Intersect is: " + intersect); // returned intersect is empty
               //I also tried: intersectObjects with ray of objects and the result is the same
  </code></pre>