title: After using the threeBSP method, the created spheres are not smooth
body: <p><img src="https://i.stack.imgur.com/eLAld.png" alt="image"></p>
  
  <p>I'm trying to change the number of segments of the sphere, but I can't cut it if I have reached the 45 limit, and there's no other way to make the sphere a little smoother.</p>
  
  <pre><code>var result;
  var sphereG = new THREE.SphereGeometry( 115, 45, 45 );
  var sphereM = new THREE.MeshPhongMaterial({color:"#fff"} );
  var sphere = new THREE.Mesh(sphereG,sphereM);
  var polyhedronG = new THREE.Geometry();
  polyhedronG.vertices.push(
      new THREE.Vector3(-200,200,-200),   //A 0
      new THREE.Vector3(-200,-200,200),   //B 1
      new THREE.Vector3(200,-200,-200),   //D 2
      new THREE.Vector3(-1,-1,-1)         //O 3
  );
  polyhedronG.faces.push( 
     new THREE.Face3( 0, 1, 2 ),
     new THREE.Face3( 0, 2, 3 ),
     new THREE.Face3( 0, 3, 1 ),
     new THREE.Face3( 3, 2, 1 )
  );
  var polyhedronM = new THREE.MeshPhongMaterial( {
      color:"#E8FBFF",
      side:THREE.DoubleSide,
      transparent:true,
      opacity:0.1
  });
  var polyhedron  = new THREE.Mesh(polyhedronG,polyhedronM);
  var boxBSP = new ThreeBSP(polyhedron);
  var sphereBSP = new ThreeBSP(sphere);
  var resultBSP = sphereBSP.subtract(boxBSP);              
  result = resultBSP.toMesh();
  result.material=new THREE.MeshPhongMaterial({color:'#fff'});
  </code></pre>