\meshAddPointBW[
  tikz,
  mode = ext,
  color = blue!70,
  meshpoint = x,
  newpoint = y,
  colorBack=red!10,
  colorNew = green!20!red,
  colorCircle = blue,
  colorBbox = black!20,
  bbox = show,
  scale=1.4cm,
  step=cavity]
  {mesh.txt}{6}