PURPOSE: To display a three-dimensional figure which is shaded and gives a spatial effect by continuously varying the color or luminance in a polygonal plane and a three-dimensional graphic which provides a feeling of the quality of the material by mapping on the polygonal plane by approximating the surface of the three-dimensional shape as a set of polygonal planes.

CONSTITUTION: The three-dimensional graphic is generated which is shaded and gives the spatial effect by a color look-up table 14 and a color information calculating means 13 and the three-dimensional graphic is generated which provided the feeling of the quality of the material by mapping the polygonal planes by mapping data 16 and a mapping processing means 15, and the three- dimensional graphics are shaded by a pixel information calculating means 17 which calculates pixel information on a three-dimensional graphic to be drawn and writes it in a frame buffer 18. One of means 131, 132, 151, 152, and 17 is provided with a perturbation processing means 21 which performs dynamic function processing wherein a perturbation term is introduced into a perturbation function to actualize fast processing.