1. A computer readable recording medium storing a 3-D game image processing program for drawing a model comprised of a plurality of polygons in a virtual game space, said 3-D game image processing program comprising the steps of: (a) storing a framed model; said frame model is made by: enlarging a 3-D model formed with a plurality of polygons; inverting a direction of a normal vector of each polygon constituting said enlarged model opposite to a direction of a normal vector of each polygon constituting said 3-D model to form a back model; and overlaying said back model on said 3-D model to form said framed model; and (b) drawing only polygons facing the direction of the viewpoint position of said virtual camera according to a drawing instruction of said framed model.