Abstract: An improved method and apparatus for classifying triangles. A description of a triangle in the form of the coordinates of its vertices is supplied to calculation logic. The calculation logic calculates a plurality or parameters of the triangle from these coordinates. These parameters are then provided to a look-up table. The look-up table has previously been programmed to include at each address the proper triangle classification for that address, with each address being a different combination of the parameters. The addresses for the look-up table cover all possible combinations of the parameters, and thus all possible triangles.

Abstract: A system for clipping polygons representing three-dimensional objects to produce a representation of the portion of the objects in a desired viewing space is disclosed. A guardband space at least partially enclosing the viewing space is defined. The polygons are compared to the guardband space to determine which polygons intersect at least one of the guardband planes defining the guardband space. The intersecting polygons are also compared to the viewing space to determine if they intersect at least one of the viewing planes defining the viewing space. Only polygons intersecting both a viewing plane and a guardband plane are clipped.

Abstract: A graphic processing system for representing three-dimensional objects on a monitor which uses a pipeline of polygon processors coupled in series. The three-dimensional objects are converted into a group of two-dimensional polygons. These polygons are then sorted to put them in scan line order, with each polygon having its position determined by the first scan line on which it appears. Before each scan line is processed, the descriptions of the polygons beginning on that scan line are sent into a pipeline of polygon processors. Each polygon processor accepts one of the polygon descriptions and stores it for comparison to the pixels of that scan line which are subsequently sent along the polygon processor pipeline. For each new scan line, polygons which are no longer covered are eliminated and new polygons are entered into the pipe. After each scan line is processed, the pixels can be sent directly to the CRT or can be stored in a frame buffer for later accessing.

Abstract: A method for determining the transfer function of a data acquisition system involves inputting a set of bilevel input test patterns to the system and measuring the system's response. The input test patterns from a complete orthogonal set. The input test patterns or the system's response can be weighted to correct for aliasing error and/or to represent any arbitrary input waveform. From the ratio of the Fourier transform of the sum of the responses to the Fourier transform of the sum of the input test patterns the transfer function is derived. In operation, the transfer function is used to accurately determine the characteristics of any input waveform to the system.

Abstract: A region defining technique for use with a computer aided design system, including a geometry specification step and a loop-chasing step which together locate the complete set of sequences of linked elements which defines the inner and outer boundaries of the region of interest in response to a single user input identifying which region is of interest. The technique permits a user with a single "pick" to select a desired region of the display for further processing such as cross-hatching or extrusion, and provides a variety of useful applications not previously offered in commercially available computer aided design systems.