anchor.diff:  
     BoundingSphere get boundingSphere => new BoundingSphere(radius: size.length * 0.5, center: center);
   
  -  intersect( BoundingBox box ) {
  -    Vector3.max(_aabb3.min, box.min, _aabb3.min );
  +  intersect(BoundingBox box) {
  +    Vector3.max(_aabb3.min, box.min, _aabb3.min);
       Vector3.min(_aabb3.max, box.max, _aabb3.max);
     }
   
  -  union( BoundingBox box ) {
  -    Vector3.min(_aabb3.min, box.min, _aabb3.min );
  -    Vector3.min(_aabb3.max, box.max, _aabb3.max );
  +  union(BoundingBox box) {
  +    Vector3.min(_aabb3.min, box.min, _aabb3.min);
  +    Vector3.min(_aabb3.max, box.max, _aabb3.max);
     }
   
     applyMatrix4(Matrix4 matrix) {
  
positive.code: 
    expandByVector(Vector3 vector) => _aabb3.copyMinMax(_aabb3.min.sub(vector), _aabb3.max.add(vector));
  
    expandByScalar(num scalar) => _aabb3.copyMinMax(_aabb3.min - new Vector3.all(scalar), _aabb3.max + new Vector3.all(scalar));
  
    bool containsPoint(Vector3 point) => _aabb3.containsVector3(point);
  
  
negative.code:   /// Computes bounding box of the geometry, updating Geometry.boundingBox.
    void computeBoundingBox() {
      if (boundingBox == null) {
        boundingBox = new BoundingBox.fromPoints(this.vertices);
      }
    }
  
  