Patent attributes
A method and apparatus for efficiently rejecting a graphics primitive that is not visible in a defined area having a maximum x and y-coordinate. A data calculation block is configured to perform the rejection calculation on two levels. In the first level, the data calculation block determines if the graphics primitive is outside of the defined area or outside of the view frustum. This determination can take as little as one clock cycle. In the second level, the data calculation block determines whether the primitive is visible based on a vector normal to the primitive and the direction of culling. This determination may take as many as five clock cycles. When many of the rejections can be performed at the first level, there is a large performance increase. Furthermore, the sooner a rejection is determined, the sooner a new primitive can be processed by the data calculation block.
