anchor.diff:        vertices = __tmpVertices;
   
         faces.forEach((face) {
  -
  -        if ( face is Face3 ) {
  -          face.vertexNormals = [ new Vector3.zero(), new Vector3.zero(), new Vector3.zero() ];
  -
  -        } else if ( face is Face4 ) {
  -          face.vertexNormals = [ new Vector3.zero(), new Vector3.zero(), new Vector3.zero(), new Vector3.zero() ];
  -        }
  +        face.vertexNormals = new List.generate(face.size, (_) => new Vector3.zero(), growable: false);
         });
   
       } else {
  
positive.code: 
      }
  
      faces.forEach((face) {
  
        if ( face is Face3 ) {
          vertices[ face.a ].add( face.normal );
          vertices[ face.b ].add( face.normal );
          vertices[ face.c ].add( face.normal );
        } else if ( face is Face4 ) {
          Face4 face4 = face;
          vertices[ face4.a ].add( face4.normal );
          vertices[ face4.b ].add( face4.normal );
          vertices[ face4.c ].add( face4.normal );
          vertices[ face4.d ].add( face4.normal );
        }
      });
  
      vertices.forEach((v) => v.normalize());
  
      faces.forEach((face) {
  
        if ( face is Face3 ) {
          face.vertexNormals[ 0 ].setFrom( vertices[ face.a ] );
          face.vertexNormals[ 1 ].setFrom( vertices[ face.b ] );
          face.vertexNormals[ 2 ].setFrom( vertices[ face.c ] );
        } else if ( face is Face4 ) {
          Face4 face4 = face;
          face4.vertexNormals[ 0 ].setFrom( vertices[ face4.a ] );
          face4.vertexNormals[ 1 ].setFrom( vertices[ face4.b ] );
          face4.vertexNormals[ 2 ].setFrom( vertices[ face4.c ] );
          face4.vertexNormals[ 3 ].setFrom( vertices[ face4.d ] );
        }
      });
    }
  
  
negative.code: 
    List colors; // one-to-one vertex colors, used in ParticleSystem, Line and Ribbon
    List materials;
    List<Face> faces;
  
    List faceUvs;
    List<List> faceVertexUvs;
  