Abstract: In a computer graphics system, a method and apparatus for scaling a line pattern having a predetermined first number of pixels to an actual line having a predetermined second number of pixels different from said first number. The total line length is divided by the line pattern length to obtain the number of line pattern repetitions and the number of remainder pixels in the actual line per line pattern repetition. An error term is incremented by the number of remainder pixels per repetition for each pixel of a given line pattern repetition that is processed. When the cumulative error term equals the line pattern length, the error term is decremented by the line pattern length and an extra pixel is generated. For lines that are shorter than the line pattern, a similar procedure is used except that when the cumulative error term equals the line pattern length, a pixel is deleted.

Abstract: A multiple-pass system for determining the primitives that are visible in a predetermined pick aperture for a "visible pick" operation. On the first pass, the primitives contained within the pick aperture and thus potentially visible are selected, and each selected primitive is assigned a pick index as an identifier. On the second pass, the pick indices of the selected primitives are rendered to a temporary frame buffer area, using a Z-buffer for hidden surface removal so that only the pick indices of the primitives visible within the pick aperture are stored in the corresponding frame buffer portion. On the third pass, the frame buffer portion corresponding to the pick aperture is read to determine the pick indices of the visible primitives. This information is then used to report back to the host the picked primitives.

Abstract: A graphic display system with the ability to use mulitiple memory buffers to produce images with a wide range of colors through bit plane encoding or to present independent application displays or to combine display images through the use of lateral bit encoding. When operated in the lateral bit encoded state, application programs can be associated with independent memory buffers or an application can use the separate buffers to create a display with animation or apparent movement. Each memory buffer can be independently associated with the display device or the images contained in the memory buffers can be mixed through the use of hardware or software image mixing to create a composite display. The combined image is use to directly control the display device and does not require the creation of an intermediate frame buffer image.