Patent ID: 7974817

Claim:
A computer-readable storage medium storing CAD program instructions for designing a structure composed of a plurality of frame members, the CAD program causing a computer having input means and display means to realize: an input function for acquiring, via the input means, maximum lengths of the structure as measured along X-axis, Y-axis, and Z-axis directions, and acquiring numbers of divisions of line segments which extend along the X-axis, Y-axis, and Z-axis directions, respectively, and have the maximum lengths, respectively; a basic shape calculation function for calculating three dimensional data representing a basic shape which is the shape of a rectangular parallelepiped divided into a three-dimensional grid, and in which lengths of sides extending along the three directions are equal to the corresponding maximum lengths of the structure, and numbers of grid surfaces of the basic shape arranged in the three directions are equal to the corresponding numbers of divisions in the three directions; a basic frame creation function for creating a basic frame of the structure from the basic shape by allowing an operator to select, via the input means, a line connecting grid points of the basic shape displayed on the display means in the form of a wire frame, to delete the line selected by the input means, and add a line between two grid points selected by the input means; a structure data calculation function for calculating structure data, which are three-dimensional data representing the structure, by arranging frame members, which are represented by three-dimensional frame member data, along lines between the grid points of the basic frame; and a drawing outputting function for outputting a drawing of the structure from the structure data.