Abstract: An automated drawing apparatus is disclosed, in which a dot string along a model line of defogging heater wires on a two-dimensional developed view of a glass window of a motor vehicle is digitized to generate functions of two-dimensional free curves corresponding to the heater wires, a width of each conductor of the heater wires is calculated on the basis of input data consisting of a heater resistance, a conductor length, sizes of heating areas, and calorific values of the respective areas, and a basic line of the heater wire is offset by the conductor width to generate conductor contours. Print patterns of heater wires are drawn automatically which eliminates precise manual drafting.