Patent ID: 6961065

Claim:
A rendering processing unit for rendering three-dimensional images on a two-dimensional screen, the three-dimensional images being each made up of a plurality of primitives, comprising: a primitive buffer in which a plurality of attribute data sets are written in association with relevant primitives, each attribute data set representing attributes of one of the plurality of primitives; and a tester that compares the plurality of attribute data sets in said primitive buffer with each other to categorize the plurality of primitives into a first group of primitives that are to be displayed on the two dimensional screen and a second group of primitives that are not displayed thereon, wherein each primitive is adapted to be overlaid on stencil data comprising allowed regions that are allowed to be displayed on the two-dimensional screen arid non-allowed regions that are not allowed to be displayed thereon, the stencil data representing the transparency and the shape of an image or images to be displayed, at least a portion of the first group of primitives being overlaid on the allowed region or non-allowed region of the stencil data, the second group of primitives being other remaining primitives than those categorized into the first group of primitives, and the rendering processing unit being configured to render the first group of primitives and not to render the second group of primitives that are categorized out by said tester.