JPH0244076B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a graphic display device, and more particularly to a raster-type graphic display device (hereinafter simply referred to as a "graphic display device") which is equipped with a thick line dot generator and is suitable for use in a graphic processing terminal. display device).

[Background of the invention]

In conventional raster-type graphic display devices, when displaying thick lines, as shown in Figure 1, after displaying one vector indicated by a circle, this vector is moved in a certain direction (in the figure, to the left). ), it was realized by adding a vector with the same length and the same slope, indicated by a ● mark.

However, this method has a problem in that even though the initial vector is a good approximation of the target vector, the final thick line vector is no longer a good approximation of the target vector. .

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to solve the above-mentioned problems in conventional graphic display devices, and to
An object of the present invention is to provide a graphic display device capable of closely approximating a target vector with a vector of arbitrary line width.

[Summary of the invention]

The present invention provides a means for holding the coordinates of starting and ending points representing a line segment, a converting means for generating dots on a grid point of X and Y coordinates based on the coordinates of the starting and ending points, and a dot generated by the converting means. In a graphic display device having a display means for displaying a pattern of dots, the converting means converts a line segment of one dot width into each
(or Y) coordinate, the above dot is generated at the above grid point which is closer to the Y (or X) coordinate, and 2
For each X (or Y) coordinate, dots are generated at lattice points that intersect the line segment with respect to each X (or Y) coordinate of the dot lattice points generated for the 1-dot width line segment.

[Embodiments of the invention]

Hereinafter, after explaining the principle of the present invention, embodiments will be explained in detail.

The present invention applies Bresenham's method, which is well known as a vector approximation algorithm.
Bresenham's method is applied to vectors with a width of one dot, but in the present invention,
This has been extended to be applicable to vectors with a width of 2 dots, and dedicated hardware has been provided to realize this.

Bresenham's method takes one point in the X (or Y) direction on a vector, and then
This is to find grid points with the same coordinates. In the example shown in Figure 2, for all X _i , Y _i is
Determine based on the criterion of the nearest grid point. That is, if q _o < q _n , P _o is the approximate point, and if q _o+1 > q _n+1 , P _n+1 is the approximate point.

Based on this, when approximating a two-dot width vector, the present invention uses both of the grid points that intersect this for all X _i as approximation points. Second
In the example shown in the figure, P _o , P _n (or P _o+1 ,
P _n+1 ) will be the approximate point.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a block diagram of a graphic display device showing one embodiment of the present invention. In the figure,
1 is a control processor, 2 is an input/output bus,
3 indicates a graphic data file that stores graphic data, 4 is a command interpretation processor, 5 is a line width register, 6 is a start/end point coordinate register, 7 is a line color register, 8 is a vector dot conversion device, and 9 is a dot data storage. The device is shown. Note that 10 is a video signal generator, and 11 is a monitor.

The control processor 1 has the function of transferring vector data to be displayed to the command interpretation processor 4 via the input/output bus 2. In the case of this embodiment, in the graphic data file 3, one vector is defined by six words of line width, line color, and starting and ending point coordinate values, as shown in FIG.

The command interpretation processor 4 stores the line width data of the first word in the line width register 5, the line color data of the second word in the line color register 7, and the line color data of the third to sixth words among the data for each six words. It has a function of setting start and end point coordinates in the start and end point coordinate registers 6, respectively. Furthermore, the command interpretation processor 4 performs the following calculation and sets the sign of the calculation result in the start/end point coordinate register.

a=X _e −X _s b=Y _e −Y _s g=|a|−|b| Here, X _s , X _e are the X coordinates of the starting point and ending point, Y _s ,
Y _e indicates the Y coordinates of the starting point and ending point.

An example of the contents of each of the above registers is shown in FIGS. 5 to 7. FIG. 5 shows an example of the contents of the line width register 5, in which the lower two bits are used to set the width of the vector. In Figure 5, n=1
corresponds to a 1-dot line (thin line), and n=2 corresponds to a 2-dot line (thick line).

FIG. 6 shows an example of the contents of the line color register 7,
Eight different colors are set using the lower three bits. The relationship with the value of the lower 3 bits is, for example, '
1,1,1' is white, '1,1,0' is yellow, '1,0,
1' is cyan, '1,0,0' is red, '0,1,1' is magenta, '0,1,0' is green, '0,0,1' is blue, '0,0, 0' is defined as black.

FIG. 7 shows an example of the contents of the start and end point coordinate register 6, and shows the signs of a, b and g (a〓, b〓 and
g〓), the coordinate values of the starting and ending points X _s , Y _s and X _e , Y _e , and the parameters of the Bresenham method.
The values of NR, PR, and RR and the sign S of RR are set. The values of the parameters NR, PR, and RR of the Bresenham method are determined as shown in FIG. 9 according to the slope of the vector defined in FIG. 8.

The vector dot conversion device 8 has a function of generating a dot string that closely approximates the given parameters based on the given parameters, and transmitting the generated dot string to the dot data storage device 9. The dot data storage device 9 has a function of storing data of the above-mentioned dot rows. The video signal generator 10 has the function of generating a video signal based on the contents of the dot data storage device 9 and displaying it on the monitor 11.

The specific configuration of the vector dot conversion device 8 and the operations among related components will be described below with reference to FIG.

This device has the function of generating dot rows of both one-dot width and two-dot width. Examples of generated dot rows are shown in FIGS. 11A and 11B. 11th
Figure A shows a case where a vector with a width of 1 dot is displayed, and one point of Y _i is determined for X _i , and the 11th
Figure B shows a case where a vector with a width of two dots is displayed, and shows a situation where two points Y _i and Y _i ' are determined for X _i .

In Figure 10, 81 is an XY counter, 82
83 indicates a counter control circuit, 83 an adder, and 84 a comparison circuit. Moreover, the arrows shown by broken lines indicate control signals, and the arrows shown by solid lines indicate the flow of data. A control signal 85 indicates an activation signal from the command interpretation processor 4, and a control signal 86 indicates a line width signal from the line width register 5. It should be noted that the control signal 87 is stored in the start and end point coordinate register 6.
The sign signal 88 indicates the sign S of the parameter RR of Bresenham's method, the carry signal of the adder 83, and the end signal 89.

Among the data set in the start and end point coordinate register 6, X _s , X _e and Y _s , Y _e are the same as the above XY
It is also set in the counter 81. At this point, X _i =X _i ′=X _s Y _i =Y _i ′=Y _s . Here, when the command interpretation processor 4 sends the activation signal 85, a dot pattern corresponding to a vector approximated by the usual Bresenham method is output in the case of a 1-dot width vector, but in the case of a 2-dot width vector. The following processing is performed.

That is, in the case of a 2-dot width vector, one is added to either X _i ' or Y _i ' based on its slope (g〓). This is because the counter control circuit 82, whose detailed configuration is shown in FIG. 12, issues an increment signal 91 or 92.
On the display, this is an operation to make the starting point two dots wide.

Next, the circuit centered around the adder 83 calculates the parameters of q _o −q _n shown in FIG. The counter 81 is set. In this case, the conditions for the counter in the Y direction (or X direction) to be incremented or subtracted by 1 according to the above settings are as follows. That is,
In the case of a 1-dot width vector, the sine signal 87
is turned on, whereas in the case of a 2-dot width vector, the carry signal 8 of the adder 83 is turned on.
8 is turned on. The signal 87 or 88 is controlled by a line width signal 86 obtained from the lower two bits of the line width register 5 as shown in FIG.

Further, as is clear from FIG. 12, the counters of X _i and X _i ' or Y _i and Y _i ' are configured to be simultaneously incremented or decremented (signals 93 to 96). Therefore, in the case of a two-dot width vector, X _i ' or Y _i ' is always greater than X _i and Y _i by one. X _i and Y _i are respectively
When X _e and Y _e become equal, the comparison circuit 84 operates and sends an end signal 89 to the command interpretation processor 4 to end the process.

In the above embodiment, the lower 2 of the line width register
The width of the vector is set using bits, but
It goes without saying that this may be set using a different number of bits in other positions.

In the above embodiment, since the vector dot conversion device 8, which is the main part, is entirely constructed of hardware, the display of the 2-dot width vector is as follows.
This has the advantage that it can be processed at high speed in the same way as a 1-dot width vector, and can also reduce the burden on the upper processor.

Here, the deviation (error) from the center point between the two-dot width vector shown in the above embodiment and the conventional two-dot width vector shown in FIG. 1 will be compared.
When the target value is y _d and the actual value is y, the error Δy is expressed as Δy=|y _d −y|. In the case of the conventional method, the above Δy has a uniform distribution from 0 to 1, and therefore the average value Δy is 0.5. On the other hand, in the case of the method shown in the above embodiment, the above Δy is 0 to 0.5
The average value Δy is 0.25.

As a result, if the size of one dot is approximately 0.3 mm, the method shown in this example can bring the display closer to the target position by an average of 0.075 mm for all thick lines with a width of 2 dots. A display that closely resembles a graphic becomes possible. As mentioned above, for a line segment with a width of one dot, Δy=0.25 as in the conventional case, and there is no change.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a means for storing a dot pattern of a figure, a means for generating a dot pattern based on information stored in the storage means, and a means for generating a dot pattern generated by the generating means. In a graphic display device having means for displaying, means for storing a line width of a display vector approximated by a set of dots on the display means;
A means for approximating a line segment having a line width of one dot is provided, and a line segment having a line width of one dot and a line segment having a line width of two dots are approximated by the output of the line width storage means.
Since it is configured to selectively output line segments with a dot line width, it has the remarkable effect of realizing a graphic display device that can closely approximate a target vector with a vector of an arbitrary line width. It is something.

[Brief explanation of the drawing]

Figure 1 shows a method for displaying thick lines in a conventional graphic display device, and Figure 2 shows
A diagram for explaining Bresenham's method, FIG. 3 is a configuration diagram showing an embodiment of the present invention, FIG. 4 is a diagram showing an example of the contents of a graphic data file, and FIGS.
Figure 7 is a diagram showing an example of the contents of registers, Figure 8
The figure shows the slope of the vector, Figure 9 shows the correspondence between the slope of the vector shown in Figure 8 and the parameters of Bresenham's method, and Figure 10 shows the vector dot conversion device which is the main part of the embodiment. FIGS. 11A and 11B are diagrams showing examples of generated dot rows, and FIG. 12 is a diagram showing details of the counter control circuit shown in FIG. 10. 1: Control processor, 2: Input/output bus, 3: Graphic data file, 4: Command interpretation processor, 5: Line width register, 6: Start/end point coordinate register, 7: Line color register, 8: Vector dot conversion device, 9: Dot data storage device, 10:
Video signal generator, 11: Monitor, 81: XY
Counter, 82: Counter control circuit, 83: Adder, 84: Comparison circuit, 85: Start signal, 86: Line width signal, 87: Sign signal, 88: Carry signal, 89: End signal.

Claims (1)

[Claims] 1 means for holding coordinates of starting and ending points representing a line segment;
A graphic display device comprising a converting means for generating dots on a grid point of X and Y coordinates based on the coordinates of the start and end points, and a display means for displaying a pattern of dots generated by the converting means,
The conversion means generates the dot for each X (or Y) coordinate of a 1-dot width line segment at the lattice point that is closer to the Y (or A graphic display device characterized in that dots are generated at lattice points of dots generated for line segments of width and lattice points that intersect said line segments for each X (or Y) coordinate.