code: function(csg) {
              if ((this.polygons.length === 0) || (csg.polygons.length === 0)) {
                  return false;
              } else {
                  var mybounds = this.getBounds();
                  var otherbounds = csg.getBounds();
                  if (mybounds[1].x < otherbounds[0].x) return false;
                  if (mybounds[0].x > otherbounds[1].x) return false;
                  if (mybounds[1].y < otherbounds[0].y) return false;
                  if (mybounds[0].y > otherbounds[1].y) return false;
                  if (mybounds[1].z < otherbounds[0].z) return false;
                  if (mybounds[0].z > otherbounds[1].z) return false;
                  return true;
              }
          }
docs: returns true if there is a possibility that the two solids overlap returns false if we can be sure that they do not overlap