HIDDEN SURFACE ERASING METHOD

PURPOSE:To normally execute the display of the edge of a three-dimensional graphic display by storing the graphic of a surface edge or on a surface in one polygon, referring the storage in case of painting-out and deciding a picture element to be hidden with the other surface when the said picture element corresponds to the stored picture element. CONSTITUTION:After the clear of a graphic memory, the graphic information of the edge, etc., namely, the presence and absence of the dot of the edge, etc., are written in correspondence to X and Y coordinates. At such a time, preferably, the Z coordinate of the surface, which is the nearest to this side, concerning the respective picture element is written to a depth value and the color information of the said dot are written to a frame memory. When the painting-out of one polygon is processed, the graphic memory is referred. Then, when the picture element to be written is recognized to be correspondent to the picture element in the graphic memory, the picture element is decided to be hidden by the other surface regardless of the Z coordinate and the picture element for painting-out is not written to the picture element. Thus, the picture element, to which the drawing of the edge and the painting-out processing are executed with being overlapped, is erased and in the display of the three-dimensional graphic, the normal erasion of the hidden surface is executed for the display of the edge.