JPS6221194A - Bold-line information generating system for graphic display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a graphic display device in a graphic CRT display device, and particularly to a line segment information creation processing method for drawing thick lines.

B9 Summary of the Invention The present invention provides, in creating and processing thick line information for displaying thick lines on a CRT display device, preparing coordinate data and line width data for a line segment that is the center of the thick line in a segment buffer; From the thick line information, the display processor obtains coordinate data for the line width with the line segment as the center.
The processing time is shortened by handling a small amount of line segment information, and a high-quality thick line display is obtained.

BACKGROUND OF THE INVENTION A graphic display device as an output device of a computer is very important for smooth conversation between humans and computers because of its visual appeal. In recent years, as computers have become more sophisticated and larger, the amount of information they handle has also increased, and display devices are required to be able to process a large amount of information quickly and easily.

A graphic display device, generally called a graphic CRT display device, has a segment buffer that stores graphic data, as shown in FIG. and a frame buffer 2 that stores bit-expanded data so that graphic data can be displayed.
Equipped with. For graphic data, a logical coordinate system called a world coordinate system is used in the segment buffer 1, and a physical coordinate system corresponding to memory addresses is used in the frame buffer 2. Graphics are displayed by a display processor (graphics processor) 3 extracting graphic data from a segment buffer 1, converting it from a logical coordinate system to a physical coordinate system, and writing it into a frame buffer 2.

4 is a digital differential analysis (DDA) processing unit, which develops graphic data into bit information on the frame buffer 2 corresponding to the figure data. A video generator 5 generates a video signal for the CRT display 6 corresponding to the read data string of the frame buffer 2.

Reference numeral 7 denotes a communication interface, which exchanges graphic data with a host computer (not shown).

D1 Problem to be Solved by the Invention In conventional graphic display devices, when displaying a line segment, the start point coordinates and end point coordinates are specified, but the thickness of the displayed line segment is a constant width; It was something that could not be changed. Furthermore, when it is desired to display a thick line, several parallel line segments are stored in the segment buffer I, which increases the amount of information required. There is a problem that the thickness of the displayed line changes when you change the amount of conversion from the logical coordinate system to the physical coordinate system, and if you do not want to change the thickness of the line, you can change the amount of conversion by using parallel line segments. It is necessary to recalculate and store it in the segment buffer 1 again. In addition, complex coordinate transformation calculations are required for each line segment data,
Increase processing time.

E6 Means and Function for Solving Problems The present invention has been made in view of the above problems, and stores coordinate data and line width data of the starting point and end point of a line segment that is the center of a thick line as thick line information in a segment buffer. registered and managed in a logical coordinate system,
When drawing a thick line, the display processor transforms the coordinate data into the physical coordinate system, and then uses the line width data to create multiple line segment data necessary to construct the thick line.The segment buffer stores the coordinate data and line data. While registering and managing only the width data, only one piece of coordinate data for one thick line is converted to the physical coordinate system, coordinate conversion, and change of the amount of coordinate conversion.

F. Embodiment An embodiment of the system of the present invention will be described in detail with reference to the drawings.

In FIG. 1, in order to register and manage thick line data, a segment buffer l stores coordinate data of the starting point and end point of a line segment that is the center of a thick line, and line width data of the thick line in a logical coordinate system. In order to display a thick line on the CR7 display device 6 from this thick line data, the display processor 3 converts the coordinate data of the central line segment into a physical coordinate system, and converts this physical coordinate data according to the line width data. Line segment data corresponding to the number of lines is created based on the physical coordinate data, bit-corresponding data to the frame buffer 2 is obtained from these data, and bold line display on the CRT display device 6 is obtained from this bit-corresponding data.

FIG. 2 shows a processing procedure for obtaining line segment data constituting a thick line from central line segment data by the display processor 3.

In the portion 210, the starting point (Xa, Ya) and the ending point (x
Determine whether the end point is on the left or right side of the display screen with respect to the start point from the coordinate data of Process the data as follows.

In detail, the coordinate values of X coordinates Xa and xb are compared,
If <xb, convert the data of the start point and end point. In addition, for part 21Ote, the distance between the starting point and the ending point DX = Xb - Xa, D
Find Y=Yb-Ya.

The processing in this part 21G is for simplifying the following processing, and is not essential processing, and the part 210 can be omitted.

When displaying a thick line, it is important to be careful that the displayed parallel line segments appear as one thick line, and that the starting and ending points of the thick line have a consistent shape. In order to solve these problems, in this embodiment, the interval between parallel line segments is taken as the minimum unit of the physical coordinate system, and the interval is taken as the minimum unit. Also, in order to display parallel line segments where the start and end points of a thick line appear to be cut at right angles to the line segment, line segments are classified by angle.

Such processing is performed by portions 220 and 230.

In part 220, the slope of the line segment is determined and the direction in which parallel line segments are generated is determined, and in part 230, dedicated processing for generating line segment data for each direction is performed. In this embodiment, the starting and ending points of the central line segment are X.

Utilizing the fact that the difference in Y coordinates has the following relationship due to the processing of the above-mentioned portion 210, branching processing in four directions is performed.

Starting point a (Xa, Ya) Ending point b (Xb, Yb) xb≧Xa DX=Xb-Xa, DY=Yb-Ya From the above relationship, the slope θ from the starting point with respect to the X axis is (1) 90
When °≧θ〉60＠ 2*DX<DY -60°>θ≧-90° (2) When 60'≧θ≧30' 2*DX
≧DYDX< 2 * DY Ya< Yb (3) When 30°>θ>-30° DX>2*
DY(4) When -30°≧θ≧-60° 2*
Each branch of DY≧DYDX<2*DY Ya>Yb is performed, and in the portion 230, parallel line segments that appear thick lines are generated in processes 231 to 234 from the line segments divided into four types according to the slope θ according to the respective angles. do.

For example, when drawing a line segment that is five times as thick as the central line segment, the lines generated by each process 231 to 234 in the portion 230 are a+ b++ at b,, a3
Assuming that b3+a4-b, the line segment data in each process is as follows.

(a) Line segment data line segment a-b by process 231 a=(Xa, Ya), b=(Xb, Y
b) Line segment at bl a+=(Xa+1. Ya)
, bl=cxb+-t, Yb) line segment at-bt
at=(Xa+2. Ya), bt=(Xb+2.
Yb) Line segment a3-bs 3. = (Xa −1, Y
a), bs= (Xb -1, Yb) line segments a, b
4 a+=(Xa 2. Ya), b4=(Xb
2. Yb) (b) Line data line segment a-b by processing 232 a=(Xa, Ya), b=(Xb
, Yb) line segment at -bl a, = (Xa, Y
a+ i), b+= (Xb -1, Yb) line segment at
bt at=(Xa-1, Ya+1), bt=(
Xb l, Yb+1) line segment a* -bs a3= (
Xa+ 1. Ya), bs= (Xb, Yb −
1) Line segment a4b4a4=(Xa+l, Ya D, b4=
(xb+t, yb 1) (c) Line segment data line segment a-b by process 233 a=(Xa, Ya), b=(Xb, Y
b) Line segment a+ bl at=(Xa, Ya+1)
, bl=(xb, Yb+1) line segment at bt
at=(Xa, Ya+2), bt=(Xb, Yb+
2) Line segment a, b3 as=(Xa, Ya 1),
ba=(Xb, Yb 1) line segment a4-b4 a
4=(Xa, Ya-2), b4=(Xb, Yb-
2) (d) Line data line segment a-b by processing 234 a=(Xa, Ya), b=(Xb
, Yb) line segment al bl a+=(Xa+1.
Ya), b+=(Xb, Yb+1) line segment a t
b! a t = (Xa+l, Ya+1),
bt=(xb+t, Yb+1) line segment a3 bl
as-(Xa, Ya l), bs=(Xb l
, Yb) line segment a, -b, a, = (Xa-1
, Ya-1), b, = (Xb-1, Yb-1) These processes and the processes in parts 210.220 have a minimum unit of 1
This is achieved through the basic processing of addition, subtraction, shifting, and comparison.

FIGS. 3(A) to 3(D) show enlarged views of the starting points and ending points of parallel line segments generated in each of the above-mentioned processes. corresponds to the output data of

G1 Effects of the Invention As described above, according to the present invention, only the coordinate data and line width data of the line segment that is the center of the thick line are registered and managed in the segment buffer for thick line information, and when drawing a thick line, the display processor To obtain expanded line segment data, the amount of data stored in a segment buffer is reduced and its management is facilitated.

Furthermore, drawing thick lines does not require complicated calculations, and the basic operations of addition, subtraction, shifting, and comparison can be performed in a short time, and display performance does not deteriorate. Furthermore, by dividing the thick line into four parts depending on the display angle and obtaining line segment data for each, it is possible to display a clear and easy-to-read thick line.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the graphic display device, Fig. 2 is a flowchart showing the line segment data generation process in Fig. 1, and Fig. 3 (
A), FIG. 3(B), FIG. 3(C), and FIG. 3(D) are diagrams of the display mode of line segment data according to FIG. ! ... Segment buffer, 2... Frame buffer, 3... Display processor, 4... Digital differential analysis processing unit, 5... Video generator, 6
... CRT display device, 7... Communication interface. Figure 3 (A) Figure 3 (C) Figure 3 (B) Figure 3 (D)

Claims (1)

[Claims] CRT by information processing by display processor
In a graphics display device that displays graphics on a display device, coordinate data and line width data of the starting point and end point of the line segment that is the center of the thick line are used as thick line information to generate and display line segments that are thicker than the basic line segment. is registered and managed in a segment buffer in a logical coordinate system, and after the display processor transforms the coordinate data into a physical coordinate system, the line width data is used to create a plurality of line segment data necessary to construct a thick line. A method of generating thick line information characterized by the following.