Patent ID: 7315310

Claim:
A clipping device for judging whether or not vertices expressed by a predetermined coordinate system are inside or outside a multi-dimensional region of an object to be drawn, comprising: a clip code generation circuit for generating clip codes obtained by setting data in accordance with results of a comparison of coordinates of said vertices and a judgment reference value of said multi-dimensional region and a negative value of the judgment reference value as bit data; a current clip register for shifting the clip codes generated at said clip code generation circuit; clip registers cascade connected to an output of said current clip register for replacing the held data with the clip codes held by the register of a previous stage; and a logic circuit for performing a logic operation with respect to all bit data set in said clip registers and setting a clip flag indicating whether or not a vertex to be judged is inside or outside the multi-dimensional region of the object to be drawn, wherein, the current clip register includes a first clip register and corresponding first multiplexer, a second clip register and corresponding second multiplexer, and a third clip register and corresponding third multiplexer, the first multiplexer selects a clip code CLPC or a parameter for initialization from the clip code generation circuit and outputs the selection to a lower 2 bits of the first register, the second multiplexer selects the output of the first register or logic 0 and outputs the selection to a middle 2 bits of the second register, and the third multiplexer selects the output of the second register or logic 0 and outputs the selection to an upper 2 bits of the third register; and said clip registers have a capacity for holding at least said plurality of clip codes.