1. A method of generating a three-dimensional (3D) shape by specifying a boundary between materials, comprising: acquiring numerical data of a boundary line of a two-dimensional (2D) shape in a plane; generating a next 2D shape by moving the 2D shape in a direction intersecting the plane based on numerical data specifying a shape of the boundary and also by copying or deforming the 2D shape; and configuring a solid based on data of a generated 2D shape.