Abstract: A polygon rendering circuit for a computer color graphics system comprising an edge stepper which steps along edges of an input polygon to determine the span of the polygon along each scan line intersected by the polygon. The coordinate values of the edges on each scan line are determined to sub-pixel resolution such that only those pixels whose centers lie within the true polygon edges (within the span width) must be drawn. Processing efficiency is improved and bandwidth is minimized by passing only those edges of the polygon which are new to that polygon and by computing the Z values in the same manner as, and in parallel with, the X values. Improved results are also possible in accordance with the technique of the invention, for since adjacent polygons compute the same edge by stepping, there can be no gaps between polygons due to round-off errors.

Abstract: A method for entering data into a computer utilizing a pop-up keyboard includes the steps of popping-up a keyboard associated with a selected field area displayed by the computer in response to a predetermined series of strokes formed by a pointer and modifying the symbols in the selected field area either in response to the selection of key field areas displayed on the popped-up keyboard or to the forming of handwritten symbols in a display field area of the popped-up keyboard with the pointer.

Abstract: Images are presented on a display to produce the perception of viewpoint motion in a three-dimensional workspace. The user can indicate a point of interest (POI) or other region on a surface in an image and request viewpoint motion. In response, another image is presented from a viewpoint that is displaced as requested. The user can request viewpoint motion radially toward or away from the POI, and can also request viewpoint motion laterally toward a normal of the surface at the POI. Radial and lateral viewpoint motion can be combined. The orientation of the viewpoint can be shifted during lateral motion to keep the POI in the field of view, and can also be shifted to bring the POI toward the center of the field of view. In a sequence of steps of viewpoint motion, the radial viewpoint displacement in each step can be a proportion of the distance to the POI so that the radial displacements follow a logarithmic function and define an asymptotic path that approaches but does not reach the POI.

Abstract: A fast vertical scan-conversion and filling method and apparatus for outline font character generation in dot matrix devices including a normalized polysegment generation engine for converting spline data to normalized polysegment data, a vertical scan conversion engine comprised of a decision table transitioner (DT) unit for identifying the location of a transition pixel relative to each polysegment or indicating that an identification cannot be made, intersection transition calculating unit (IT) for calculating the position of a transition pixel relative to each polysegment, and a transition pixel coordinate generating unit responsive to the normalized polysegment data and input received from the DT and IT units and operative to generate signals corresponding to the X and Y coordinates of each transition pixel, and a parity filling engine responsive to the x and y coordinate segment and operative to generate bit mapped character image data for use in driving a bit map print or display device.

Abstract: A method, in a computer graphics system, manipulates the vertices contained within a group of possibly self intersecting, free space, over lapping polygons, into simple, convex polygons. A normal axis to the complex polygon is determined such that the surface of the polygon is viewed along this normal axis. The polygon surface is then bounded by a rectangle and subdivided into a group of slabs, or smaller rectangles, each rectangular slab being bounded by a pair of interior vertices of the complex polygon. An active edge table is used to store values corresponding to the edges crossing through the slabs, which are used to determine if these edges cross are another at any point within the slab. If a crossing point does exist, the slabs are divided at the crossing point into rectangular sub-slabs until it is determined that no edge intersects another edge within the sub-slabs, of the original slab being considered.

Abstract: A scan conversion device generates segment direction information on the basis of vector information representing outlines of a pattern such as graphic FIGURES. An image drawing data generating device generates raster information inclusive of image drawing direction information in accordance with predetermined image drawing direction rules on the basis of the segment direction information, and further generates new image drawing data to be stored into a frame memory in accordance with predetermined image drawing rules on the basis of the raster information and previous image drawing data read from the corresponding memory area of the frame memory. The frame memory stores the image drawing data on a dot-by-dot basis. A dot pattern converting device converts the image drawing data provided from the frame memory into a dot pattern signal in accordance with an image drawing mode as set.

Abstract: A method for determining the illumination of an illuminator at a selected point P in an image volume to be projected on an image screen surface by a computerized image generator, operates by: decomposing the illuminator into at least one of spherical, beam and cylindrical sources; determining a direction of incidence of the light from each source at point P in the image volume; determining the extent of the source and the attenuation of illumination with distance from that source; then determining a set of color light intensities at point P in the image volume due to the light from the particular source; and translating the incidence direction and color intensities from point P to a displayable incidence direction and a displayable set of color illumination intensities at a corresponding projection location on the image screen surface.

Abstract: An arrangement for addressing a frame buffer memory including apparatus for selecting from the address bits designating a position in the frame buffer of a pixel to be displayed on an output display the bits indicating the word address of the pixel in a particular row of the frame buffer, apparatus for multiplying the word address by a fraction to provide a new word address, apparatus for recombining the new word address with the row address to provide a new address in the frame buffer for the information regarding the pixel to be displayed, and apparatus for controlling the storage of a data word describing the pixel beginning at a selected byte of the data word whereby the storage in the frame buffer of an unused portion of a data word describing the pixel may be eliminated.

Abstract: A circuit and method of operation which controls the reordering of data as it is transferred from one memory to another. The data to be reordered is stored in a memory such that the ordinate bit position within a data word is uniquely associated with a particular input to a data bus. The bus inputs, however, are connected to the VRAM in an arrangement contrary to the desired ordinate association with the compressed data word. A swizzle logic circuit operates to allow graphic compressed data to be reordered for presentation to the block-write inputs of a VRAM.

Abstract: A two- or three-dimensional geometric modeling apparatus in which a two- or three-dimensional shape is input to a processing unit via an input unit to form a shape, the formed shape is extracted from the processing unit and displayed on a display unit, data for changing is input to the processing unit from the input unit in order to change the displayed shape or scale, and the shape or scale is changed on the basis of predetermined stored information, thereby displaying the changed shape or scale on the display unit. The predetermined stored information is stored as a history such that a plot method and plot contents of each of plot operations executed upon formation of the shape and an order of the plot operations correspond to a geometric constraint for defining the shape to be formed. When a portion to be changed of the shape or scale is specified, the history is referred to search a plot operation forming the specified portion to be changed.

Abstract: A method for controlling a three dimensional cursor's position on a display with a two dimensional control device by generating a translation signal to the display when the control device was moved in such a way as to indicate that the user intended a translation of the cursor and generating an elevation signal to the display when the control device was moved in such a way as to indicate that the user intended an elevation of the cursor. Analysis of the single movement alone, however, being only the first step in truly interpreting the user's intentions, the present invention also includes steps for preventing certain types of control device movements from being interpreted incorrectly.

Abstract: This method and apparatus are suitable for inclusion in the "graphics circuit board" of a personal computer. The digital output of the computer is used to plot a series of "pixel pairs" which, taken together, closely approximate the desired path of a line to be drawn on a display device such as a color cathode-ray tube. The addresses and relative intensities of the pixels of each pair and of the series are computed so as to produce a line that is substantially free from the "jaggies" resulting from "aliasing" in prior-art apparatus. Computation of addresses relies upon both integer and floating-point numbers.

Abstract: A master-slave processor human interface system. An electronic device, a slave processor for controlling the electronic device and performing certain computational functions, a master processor for controlling the slave processor, an input device and an output device associated with the master processor, and an information storage device are provided. Individual slave processor programs are selected, retrieved from the information storage device, and loaded into the slave processor for implementing corresponding functions of the slave processor and electronic device, while a single master processor program which adapts itself to the selected slave processor program accepts input data and operational selections and displays output information according to a predetermined spatial arrangement for each such function, thereby providing the human interface.

Abstract: A high performance computer graphics image computation system architecture is disclosed. The system architecture includes a computational processor ring which includes a plurality of closely coupled computational subsystems. The computational subsystems operate asynchronously and each is interconnected with two adjacent computational subsystems. The architecture of the processor ring allows rapid communication between the computational subsystems while avoiding a deadlock condition. The system architecture also includes a video processor ring wherein a plurality of video processors are synchronously linked together. A plurality of local communication paths couple the computational subsystems to the video processors. The video processor ring is able to move massive amounts of data, in the form of digital video signals, from various points within the system.

Abstract: A text processing apparatus has a frame preparation function wherein a synthesized frame is prepared containing character information superposed on a prepared frame. The apparatus has structure to append control information to a space that is input as character information so that, when character string that has character information with a space is superposed over a prepared frame, the space input as character information is preserved as a space in the synthesized frame.

Abstract: An image forming apparatus has an operation part for specifying information to be recorded on a sheet, a recognition part for recognizing the information specified by the operation part, an input interface for receiving sequentially a first serial image data representing an image, a bit image generation part supplied with the first serial video data for forming bit images in response thereto, a memory having a memory area for storing the bit images formed by the bit image generation part in the memory area, a comparison part operatively connected on the one hand to the memory for reading out the bit images stored therein and on the other hand to the recognition part for receiving the information to be recorded on the sheet, the comparison part producing the output such that the output is changed with increasing occupation of the memory area by the bit images, and a reporting part connected to the comparison part for receiving the output from the comparison part and for displaying the proportion of the memory

Abstract: A method and apparatus for determining a uniform step size with respect to pre-transformation derivative bounds for tessellation of a graphic primitive wherein the step size results in triangles which meet post-transformation thresholds. To maximize the efficiency of rendering curved surfaces while ensuring that the tessellation criteria is met, a maximum scale value for the non-linear transformation between device coordinate (DC) and lighting coordinate (LC) space is determined and utilized to translate the tessellation threshold in DC space to a tessellation threshold value in LC space. Information regarding the curved surface to be rendered is transformed to the LC space from the model coordinate (MC) space. The derivative bounds of the curved surface, and the tessellation threshold value are utilized to determine the uniform step size to tessellate triangles representative of the curved surface.

Abstract: A visual simulation system (10') and method for digital computer graphics processing is described whereby the system (10') reduces the undesirable effects of aliasing on the digital computer images (59) rendered in the simulation. Real-Time Pixel Mixing (RTPM) is accomplished by processing each pixel (P.sub.f) of a digital computer foreground image (60, 62) generated in real-time with the corresponding pixel (P.sub.b) of a previously generated background image (64). The effect of the processing is to overlay the foreground image (60, 62) on the background image (64) and cause the pixels on the periphery of each object rendered in the foreground image (60, 62) to be color blended with the corresponding pixels of the background image (64) in such a manner as to "soften" the transition between the foreground (60, 62) and background (64) images.

Abstract: The center line (CL) of a line graphic (A) is represented by a set of linear segments. A bent part (P.sub.2 -P.sub.9) is specified and a train of linear segments representing the bent part remains in a process of correcting defect the line graphic. After the defect is corrected, the train of linear segments is converted into a curve to thereby obtain a graphic having a curve.

Abstract: A system that allows a user of an iconic programming system to specify data input constraints on any terminal of any icon of an iconic network program defined within the system. When adding connecting lines between icons during program creation, the iconic programming system verifies that any input constraints defined for an input terminal match the data type and shape of the data being sent by an output terminal. If a mismatch occurs, the system will allow a connection only if a method is available for converting the type and shape of the data. During the execution of the iconic network program, the constraints for each input terminal are compared to the type and shape of data being received on the terminal. Processing will continue only if the constraints match or the data can be converted.