Method for displaying characters with improved legibility at relatively low resolution by modifying the center point fill method and displaying additional pixels as needed to maintain connectivity and avoid dropout problems. Additional pixels are turned on as needed where a black section of the character crosses the midline between two adjacent horizontal or vertical pixel centers. If the intersections of a black section of a character with a midline is entirely within one pixel which is not otherwise turned on, then that pixel is turned on; if a black section of a character crosses between two such adjacent pixel reference points in parts of both pixels, and if neither pixel is already on, the pixel having more of the black section, measured along the line between pixel centers, (or other reference points), is turned on.
Apparatus and method for generating displayable information expressive of a three dimensional solid object. The apparatus includes a processor (12,16) for expressing the object in a Constructive Solid Geometry representation thereof so as to be comprised of one or more primitive objects. The apparatus further includes a processor (18, 20) for repetitively evaluating the one or more primitive objects to determine displayable faces thereof. A depth interval buffer (20) is responsive to the operation of a scan conversion processor (18) for detecting when a predetermined number of repetitive evaluations occur without causing a change in the determination of a displayable face and for causing the operation of the evaluation processor to terminate. Toleranced depth tests are used to remove dangling faces or edges and to properly handle coincident faces. Pixel-centering is employed to improve the accuracy of depth tests and to identify pixels upon which a product projects. Shadowing is accomplished using a two-pass scan-conversion technique with an auxiliary shadow-buffer (ZS).
A rendering device for converting input information into a bit map including a Bezier subdivision processor responsive to Bezier curve information describing a Bezier curve of an image. The Bezier subdivision processor performs at least one subdivision on the Bezier curve if the Bezier curve is greater than a desired resolution of a bit map to produce subdivided Bezier curves until all subdivided Bezier curves are at about the resolution of the bit map. The Bezier subdivision processor produces cross information from each Bezier curve which makes one crossing of a grid having the resolution of the bit map. The rendering device also includes a digital processor responsive to the cross information and operative to produce a bit map of the image from the cross information. A method for producing cross positions of Bezier curves with a grid of the present invention includes receiving a Bezier curve, sequentially subdividing the Bezier curve into a plurality of subdivided Bezier curves until each Bezier curve crosses less than a plurality of times with cell boundaries of a grid of a desired resolution, and developing the Cartesian coordinates and direction of each of the crosses of a Bezier curve with a boundary.
A memory construct including a stack which is capable of holding one or more data items of a type and which operates as a LIFO memory, and a queue which is capable of holding one or more data items of the same type until they are used. The queue operates as a FIFO memory associated with the stack so that when the stack is empty, data is read from the queue and when the stack is not empty, data is read from the stack.
A rendering device for converting input information into a bit map including a Bezier subdivision processor responsive to Bezier curve information describing a Bezier curve of an image. The Bezier subdivision processor performs at least one subdivision on the Bezier curve if the Bezier curve is greater than a desired resolution of a bit map to produce subdivided Bezier curves until all subdivided Bezier curves are at about the resolution of the bit map. The Bezier subdivision processor produces cross information from each Bezier curve which makes one crossing of a grid having the resolution of the bit map. The rendering device also includes a digital processor responsive to the cross information and operative to produce a bit map of the image from the cross information. A method for producing cross positions of Bezier curves with a grid of the present invention includes receiving a Bezier curve, sequentially subdividing the Bezier curve into a plurality of subdivided Bezier curves until each Bezier curve crosses less than a plurality of times with cell boundaries of a grid of a desired resolution, and developing the Cartesian coordinates and direction of each of the crosses of a Bezier curve with a boundary.
A computer graphics program executed by a processor (12) for generating a graphics chart on a computer display (26) are provided. The program includes instructions for controlling the placement of objects on the chart and for relating data to the objects in the chart. The program also includes instructions for generating cause and effect diagrams directly onto the computer display (26).
