公开(公告)号：DE3275669D1

公开(公告)日：1987-04-16

申请号：DE3275669

申请日：1982-12-30

Applicant: IBM

Inventor： RICHARDS JOHN PETER ,  BRESENHAM JACK E ,  GAY ADRIAN C

IPC: G06F3/153 ,  G06T11/00 ,  G09G5/00 ,  G09G5/32 ,  G09G5/36 ,  G09G5/393 ,  G09G5/42 ,  G09G1/16 ,  G09G1/06

Abstract: The invention concerns a graphics display system of the kind having a refresh raster display device, a line clipping mechanism for clipping line primitives for viewing in a selected rectangular viewport having horizontal and vertical edges parallel to the X and Y axes respectively of the display area of the display device, and a vector-to-raster converter for converting the clipped lines to patterns of discrete pels in a refresh buffer, the vector-to-raster converter including an incremental line drawing mechanism responsive to line information supplied by the clipping mechanism to draw the line starting at one endpoint and proceeding towards the other. In such a system, for at least some lines of a kind which have a first endpoint in the viewport and the second endpoint outside the viewport, the clipping mechanism is arranged to avoid calculating the intersection point of the line with the viewport edge intersected by the line, and the vector-to-raster converter is arranged to start the line drawing mechanism at the first endpoint and halt the line drawing mechanism when the currently generated coordinate along the display axis normal th the said viewport edge equals the coordinate of the viewport edge along the same axis.

公开(公告)号：CA2021830C

公开(公告)日：1995-01-10

申请号：CA2021830

申请日：1990-07-24

Applicant: IBM

Inventor： BUTLER NICHOLAS D ,  GAY ADRIAN C

IPC: G09G5/36 ,  G06T11/40 ,  G09G5/393 ,  G09G5/00

Abstract: DISPLAY SYSTEM A computer graphics system is presented, having display logic (92) comprising a destination bit map (11) containing a plurality of image bits which map to a plurality of pixels for presenting an image, an auxiliary bit map (1) containing a plurality of area boundary bits representing pixels defining an area boundary line which encloses an area of the image, area filling logic (7) for operating upon those image bits enclosed by the area boundary line in order to fill the area with a particular pattern and colour, characterised in that the display logic further comprises area boundary drawing logic (5) having line segmentation means to resolve the specified boundary line into a plurality of intersecting two pixel line segments which can, from that time forward, be operated upon separately to define the area boundary bits in accordance with conventional area boundary drawing rules.

公开(公告)号：CA2000005A1

公开(公告)日：1990-08-27

申请号：CA2000005

申请日：1989-10-02

Applicant: IBM

Inventor： BUTTIMER MALCOLM D ,  GAY ADRIAN C ,  BUTLER NICHOLAS D ,  BATES MATTHEW D ,  KIM JONG H

IPC: G06T11/20 ,  G06F9/302 ,  G06F9/318 ,  G09G5/20 ,  G06F9/06

Abstract: DATA PROCESSOR A data processor comprises storage for each of first, second and third values, a processor condition register for processor condition codes and logic for decoding instructions including a specific instruction defining an operation between the first value and either the second value or the third value. The selection of the second or the third value is made by the processor in dependence on the state of the processor condition code. The invention is of particular, but not exclusive application for the plotting of lines in a display system. In an example of a display system incorporating such a data processor, a pixel can be plotted on each processor instruction cycle. UK9-89-003

公开(公告)号：CA1304524C

公开(公告)日：1992-06-30

申请号：CA573164

申请日：1988-07-27

Applicant: IBM

Inventor： BUTLER NICHOLAS D ,  GAY ADRIAN C ,  BRESENHAM JACK E

IPC: G06F3/153 ,  G06T11/20 ,  G09G1/10 ,  G09G5/20 ,  G09G5/36 ,  G06K15/22 ,  G09G1/14

Abstract: LINE GENERATION IN A DISPLAY SYSTEM The present invention concerns a line generator and a method for determining the individual pixels to be plotted for a line to be drawn in a display system. Coded representations of a plurality of lines are stored in a line definition table, the coded representation of each individual line comprising a string of data items representing the transitions between adjacent pixels to be plotted for drawing said individual line. Preferably, only coded representations of lines up to a predetermined size (ie. the length of the line in the case of a straight line) are stored in the line definition table and strings of data items for representing the pixels to be plotted for longer lines to be drawn are still calculated as in the prior art. In this case, means are provided for determining whether there are coded representations of a line to be drawn in the line definition table, or not, and for passing control to the appropriate logic for determining the pixels to be plotted. In a preferred embodiment, the string of data items forming the coded representation of a line to be drawn is a string of binary digits and the value of each bit in the string represents a transition in one of two directions. This provides a very compact representation of the line.

公开(公告)号：DE3379004D1

公开(公告)日：1989-02-23

申请号：DE3379004

申请日：1983-06-30

Applicant: IBM

Inventor： BRESENHAM JACK E ,  BOWATER RONALD J ,  GAY ADRIAN C ,  SHEEN NORMAN R

IPC: G09G5/32 ,  G09G1/10 ,  G09G5/24 ,  G09G1/16

公开(公告)号：CA1224290A

公开(公告)日：1987-07-14

申请号：CA455228

申请日：1984-05-25

Applicant: IBM

Inventor： BRESENHAM JACK E ,  BOWATER RONALD J ,  GAY ADRIAN C ,  SHEEN NORMAN R

IPC: G09G5/32 ,  G09G1/10 ,  G09G5/24 ,  G09G1/16

Abstract: METHOD OF STORING CHARACTERS IN A DISPLAY SYSTEM In a method of storing characters in a display system having a display device with an orthogonal matrix of addressable points, each character is represented as a succession of strokes each constrained to lie in one of the eight fundamental directions of the matrix and, except for the first stroke, each starting at the end of the previous stroke. Each such stroke is stored in a binary coded form which includes a first binary number (direction code) defining the angular direction of the stroke, a second binary number (length code) defining a number of matrix steps from one addressable point to the next along the stroke in that direction, and a third binary number (move/draw code) defining the visibility of the stroke. In order to facilitate character rotation by any multiple of 45.degree. the direction code defining each fundamental direction corresponds to the addition modulo 2n of a binary constant to the direction code which defines the fundamental direction at 45.degree. thereto in a given direction of rotation, where n is the number of bits in the direction code.