Window clipping methods in graphics accelerators

How some recently introduced graphics accelerators address window clipping is discussed. Some graphics accelerators can download the window-clip rectangle data structures used to represent the visible areas of a window to specialized RAM or hardware registers. These accelerators have special hardware and/or software to hold the clipping information and to properly clip graphics primitives. Others use window clip planes, which allow easy hardware representation of windows with arbitrary shape and complexity. They are ideal for clipping graphics output to nonrectangular windows because graphics output performance does not degrade as the number of rectangles needed to represent the window increases. CPU-based window clipping is examined. Devices in each of these classes are described.<>