anchor: ChainShape:getPoints
  Returns all points of the shape.
  x1, y1, x2, y2 = ChainShape:getPoints()
  x1 number The x-coordinate of the first point.
  y1 number The y-coordinate of the first point.
  x2 number The x-coordinate of the second point.
  y2 number The y-coordinate of the second point.