To permit the use of selectively combined functions of three- dimensional applications ranging widely from CAD to games for three- dimensional shape generation.

A basic phase structure and a geometric structure which constitute the solid of a solid modeller are selected as essential components (base) out of phase structures of different level and geometric structures of different level and in the essential component, an abstract interface class is defined; and a phase structure and a geometric structure of upper level are selected by a virtual function call passed through the abstract interface and the phase and geometric structures as the essential components and the phase structure and geometric structure positioned at upper levels are combined to obtain structures needed for an application, thereby generating a three-dimensional shape.