SORTING PROCESSING SYSTEM AND IMAGE SYNTHESIZING SYSTEM USING THE SAME

A sorting processing system most suitable for use in an image synthesizing system processing images in real time is provided. A Z-representative value computing unit computes a Z-representative value from the Z-coordinate values of the respective vertices in a polygon which are inputted from a 3-D computing unit. The Z-representative value is inputted into a polygon shift value adder unit or polygon fixed Z-value setting unit to perform the addition of shift value or the setting of fixed Z-value for every polygon. An object shift value adder unit and object fixed Z-value setting unit perform the addition of shift value and the setting of fixed Z-value for every 3-D object. On the other hand, an absolute priority setting unit sets an absolute priority bit to which a shift value is added by polygon and object absolute priority shifting units for every polygon and 3-D object. A sorting Z-value is formed from the above computation results and then inputted into a sorting unit. According the priority determined by this sorting Z-value, the polygon image data is outputted toward an image supply unit.