JPH0727357B2 - Straight line drawing method in graphic device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a straight line drawing method in a graphic device, and more specifically, both ends of the straight line end perpendicularly to the direction of the straight line and have a uniform line width. The present invention relates to a straight line drawing method for drawing a straight line.

[Background of the Invention]

In a graphic device that uses pixels as the minimum unit of display, one of the conventional methods for drawing a straight line having a line width is the x-axis or the y-axis with respect to two specified points that specify the drawing position of the straight line. There has been a method of shifting lines by one pixel in parallel to the direction and drawing multiple lines by a specified number of lines. An example of displaying a straight line having a line width of 3 pixels and a line type of a broken line by this method is shown in FIG. 11 (a). In FIG. 11 (a), circles represent pixels on the display, and hatched parts represent actual drawing points. This also applies to FIGS. 11 (b) and 11 (c) shown below.

As is clear from Fig. 11 (a), in this method,
There are problems in that (1) both ends of a straight line do not end vertically to the direction of the straight line, and (2) line styles (line patterns) are not aligned in the vertical direction of the straight line.

Therefore, as an improvement of the method shown in FIG. 11 (a), a straight line drawing method as described in JP-A-59-136784 has been proposed. In this method, when drawing parallel multiple lines sequentially, the drawing position of the straight line is specified.
By determining the angle of the straight line from the coordinate values of the two designated points 56 and 57, and configuring the hardware to shift the start position of the line pattern array to realize the line style, the direction of the straight line can be changed. The line style cuts are aligned in the vertical direction. A display example by this method is shown in FIG. 11 (b). In this method, FIG. 11 (b)
As shown in Fig. 11, among the problems described in Fig. 11 (a), the problems related to the line style have been improved, but the other problems have not been improved.
There was also a problem in that special hardware had to be added to the implementation.

Further, as another method, there is a method in which point sequences are obtained at both ends of a straight line in a direction perpendicular to the direction of the straight line, and the point sequences at both ends are connected by straight lines. An example of displaying a straight line having a line width of 3 pixels by this method is shown in FIG. 11 (c). In FIG. 11 (c), the point sequence 64 consists of points 64-a, 64-b, 64-c, and the point sequence 55 consists of points 65-a, 65-b, 65-c, Both show a series of points at both ends of the straight line. The point sequences 64, 65 at the both ends of the points are first calculated by the geometric calculation from the coordinates and the line widths of the two designated points 56, 57 given in advance, and the points at the four corners of the straight line 64-a, 64-c, The coordinate values of 65-a and 65-c are obtained, respectively, and then they are used to calculate points 64-a and 64-
It is obtained by determining the respective point sequences that respectively form the straight line connecting the points c and c and the straight line connecting the points 65-a and 65-c.

FIG. 12 is an explanatory diagram for explaining in more detail the method of obtaining the above-mentioned four corners of the straight line. In FIG. 12, the coordinate values of the two designated points 55, 56 are (x ₀ , y ₀ ) respectively. , (X ₁ , y
₁ ), the length of the straight line is l, and the line width in the direction perpendicular to the direction of the straight line is d.

For example, the coordinates of one point 90 among the four corner points to be obtained are calculated from the similarity relationship of the two triangles shown by the broken line, Is asked. The other points 91, 92, 93 at the four corners can also be obtained from the deviation of the point 90 from the designated point 55 and the coordinate values of the designated points 55, 56.

In this method, compared to the method shown in FIGS. 11 (a) and 11 (b), the ends of the straight line and the line style breaks are
It is improved in that it aligns in the direction perpendicular to the direction of the straight line.

However, the following two new problems have arisen.
First, there is a problem that the omission of the fill occurs inside the straight line. In other words, in this method, as shown in FIG. 11 (c), the point sequences at both ends obtained in the direction perpendicular to the straight line direction are obtained.
64, a point sequence 65 where x and y coordinate values change simultaneously, that is, between points 64-a and 64-b, points 65-b and 65.
Therefore, when a point sequence forming a straight line connecting between the point sequences at both ends is drawn, an undrawn point 53 as indicated by a broken circle is generated.

Another problem is that it takes a lot of processing time to draw a designated straight line. The reason for this is
This is because complicated calculations are required to find the points at the four corners of the straight line, and the filling method that draws multiple parallel lines between the point sequences at both ends of the straight line is used.

[Object of the Invention]

The object of the present invention is to solve the above-mentioned problems of the prior art,
In the graphic device, the line width has the specified line width, the both ends of the line and the specified line style cuts are aligned in the direction perpendicular to the direction of the line, and there is no omission of the fill inside the line. It is to provide a straight line drawing method for drawing a straight line at high speed.

[Outline of Invention]

In order to achieve the above-mentioned object, in the present invention, when drawing a straight line having a predetermined line width, the processing device follows the program stored in the main memory and specifies the first and second designated lines.
The coordinates of each point of the point sequence forming the straight line having the length corresponding to the designated line width including the first designated point in the direction perpendicular to the direction of the straight line connecting the designated points of , For each of these points, after obtaining relative position coordinates relative to the first reference point contained therein and storing them in the main memory,
Between the first and second reference points, the coordinates of the second reference point having a positional relationship equivalent to the positional relationship of the first reference point with respect to the first specified point with respect to the second specified point are obtained. Each position coordinate of the point sequence forming the straight line connecting the points is obtained, and each time the position coordinate is obtained, each of the position coordinates with respect to that point is referred with reference to the relative position coordinates also stored in the main memory. The point coordinates of the points existing at each relative position based on
When the coordinate value and the y coordinate value are different, one of the two points has the same x coordinate value and the other point also has the same y coordinate value, and the obtained point coordinates Predetermined point information is stored in each memory position in the display memory corresponding to the coordinate position of the raster display, and then the point information stored by the display controller is read and displayed on the screen of the raster display. A straight line having a predetermined line width is displayed on the screen. Further, according to the present invention, when a straight line having a uniform width is drawn on both sides of a line connecting two designated points for designating the drawing position of the straight line, the processing device selects one of the two designated points. From the coordinate position of one of the points, a sequence of points is sequentially obtained by the number corresponding to the half of the line width specified in the direction perpendicular to the direction of the straight line, and the reached point is set as the first reference point. Folding from a point In the direction of the designated point, the point sequence is sequentially obtained by the number corresponding to the distance of the designated line width, and the obtained point sequence is set as the first point sequence. It's something I got to get.

Example of Invention

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of a graphic device used for implementing the present invention.

In FIG. 2, 10 is a main memory (hereinafter abbreviated as MM), 11
Is an external file control device (hereinafter abbreviated as EFI), 12 is an external file (hereinafter abbreviated as EF), 13 is a processing unit (hereinafter abbreviated as CPU), 14 is a keyboard control device (hereinafter abbreviated as KBI) Abbreviated), 15 a keyboard (hereinafter abbreviated as KB), 16 a printer controller (hereinafter abbreviated as PRI), 17
Is a printer (hereinafter abbreviated as PR), 20 is a graphic processing unit (hereinafter abbreviated as GPU), 22 is a raster display (hereinafter abbreviated as D), and these are connected to each other by a common bus 21. .

FIG. 3 is a block diagram showing in detail the configuration of the GPU 20 shown in FIG.

In FIG. 3, 23 is a segment memory (hereinafter abbreviated as SM), 24 is a graphic processing device (hereinafter abbreviated as GP),
Reference numeral 25 is a display memory (hereinafter abbreviated as FM), 26 is a display control device (hereinafter abbreviated as DC), and these are connected to each other by an internal bus 27.

SM23 can be replaced by MM10, and GP24 is
The CPU 13 can have that function.

The operation for drawing a graphic on D22 in the graphic device shown in FIG. 2 will be described with reference to FIG.

A program for drawing a graphic on D22 and graphic data (generally a graphic drawing command sequence) are stored in MM10.
The CPU 13 reads the program from the MM 10 and executes it. In order to display a graphic on D22, the CPU 13 first reads an instruction to transfer the graphic data from the MM10 to the SM23 in the GPU 20 from the program and executes it. Next, the CPU 13 fetches from the MM 10 an instruction to request the GP 24 in the GPU 20 to execute drawing, and executes the command.

Upon receipt of the execution request, the GP24 in the GPU20 extracts the corresponding figure data from the SM23, converts it into pixel data, and stores it in the area on the FM25 corresponding to the pixel on the D22. The DC 26 cyclically reads out the FM 25 at regular intervals, and displays the corresponding pixels according to the read out attributes. By this,
The display of D22 always reflects the data stored in FM25.

FIG. 4 is a schematic diagram showing an example of screen output by the straight line drawing method of the present invention.

In FIG. 4, circles represent pixels on the display, and those with diagonal lines represent actual drawing points. Also, the point
55 and 56 are designated points on both ends of the straight line, and this figure shows a straight line 33 with equal width on both sides centering on the straight line connecting points 55 and 56.
This is an example of drawing (broken line).

As shown in FIG. 4, the straight line drawn according to the present embodiment has both ends terminating perpendicularly to the direction of the straight line, and the line style is also drawn so that the pattern cuts are aligned in the direction perpendicular to the direction of the straight line. It

Then, in the graphic device shown in FIG.
An operation for drawing a straight line as shown in the figure will be described.

In the following description, the scanning direction of the raster display is the x-axis, the direction perpendicular to the x-axis is the y-axis, and the inclination angle of the straight line to be drawn is 0 ° in the positive direction of the x-axis and up to 45 ° in the counterclockwise direction. The description will be limited to the range. Regarding other angles, by changing the x-axis and y-axis and changing the sign of the increment in the x-axis direction or the y-axis direction in the digital differential analysis method (hereinafter referred to as DDA) described later in FIG. It can be handled similarly.

FIG. 5 is an explanatory diagram showing the relationship of the corrected line width d ′ with respect to the designated line width d and the inclination angle θ of the straight line.

As described above with reference to FIGS. 2 and 3, the CPU 13 is the GPU 20.
If a straight line drawing execution request is issued to the GP24 inside as a drawing drawing execution request, the GP24 that has received the execution request
Performs the following processes in order to draw a straight line having a width as shown in FIG.

For the designated line width d, a corrected line width d '(see FIG. 5) for drawing a straight line that changes depending on the inclination of the straight line is obtained.

At one end of the straight line, a point sequence having a line width d (a point sequence in which the increment in the y-axis direction is equal to the corrected line width d ′) is obtained in a direction perpendicular to the direction of the straight line with the designated point 55 as the center, Using one point in the point sequence as a reference point, the relative position coordinates of each of the other points with respect to the reference point are stored in SM23.

While referring to the relative position coordinates stored in the SM23, from one end of the straight line to the other end, the point coordinates of a series of points that are continuous in the direction perpendicular to the straight line The point information (pixel data) is stored in the memory position of the FM25 corresponding to the obtained point coordinates.

When the point information is stored in the FM 25, the point information is obtained by cyclically referencing the line pattern sequence stored in the SM 23 to realize the line style.

The above is the outline of the processing operation of GP24, and these will be described in detail one by one below.

First, before describing the processing operation, the table necessary for drawing a straight line having a width will be described.

FIG. 6 is a schematic diagram showing a table required for straight line drawing in the present invention. Each table shown in FIG. 6 usually exists on the SM 23.

The table shown in FIG. 6A is a straight line attribute table.

In FIG. 6 (a), areas 40 and 41 are designated points 5 respectively.
The x coordinate and the y coordinate of 5 are stored, and the areas 42 and 43 store the x coordinate and the y coordinate of the designated point 56, respectively. The area 44 stores the designated line width d shown in FIG. 5, and the area 45 stores the correction line width d'used for straight line drawing. Area 46 stores a line pattern for realizing a line style. The line pattern is represented as a bit string, and bits having two states of φ ... not drawn and 1 ... drawn are prepared for the number of pixels in one cycle of the line style.

The table shown in FIG. 6 (b) is a work table for drawing a straight line.

In FIG. 6 (b), areas 47 and 48 are respectively obtained as described later, and the x coordinate and y of the reference point 57 shown in FIG. 7 are obtained.
The coordinates are stored, and the areas 49 and 50 also store the x coordinate and the y coordinate of the reference point 58 shown in FIG. 7, respectively. Also, the offset array 51 is a GP as described later.
24 is the coordinate value of the point sequence forming a straight line centered on the specified point and perpendicular to the direction of the straight line to be drawn and having a length for the correction line width in the y-axis direction, from the reference point. After the deviations of the x-coordinate and the y-coordinate are obtained, the deviation value of the x-coordinate of the point is stored in order from the point having the smallest deviation of the y-coordinates obtained. The size of the offset array 51 is determined by the maximum specifiable value of the designated line width d.

The table shown in FIG. 6 (c) is a line width correction table, which is used to obtain the correction line d'from the inclination of the straight line and the designated line width d. As can be seen from FIG. 5, the relationship between d and d ′ is d ′ = dcosθ (Equation (2)), and the slope of the straight line Substituting into equation (2), Is represented. Since the actually required value of d'is an integer value, Let d ′ be the integer value closest to the value of. Therefore, equation (3)
For each of the line widths d that can be specified, the respective maximum values of the slopes of the straight lines for obtaining the respective integer values of the corrected line width d ′ are respectively obtained, and these are stored in FIG. 6 (c). ) Is a line width correction table shown in FIG.

In FIG. 6 (c), the numbers arranged at the upper end indicate the value of the line width d, and the characters arranged at the left end indicate the value of the corrected line width d '(d is the value of the line width d described above. Substituted numbers) and the numbers with a decimal point in each block indicate the value of the slope of the straight line.

That is, in this line width correction table, the contents in the block of the i-th row from the first block in the column corresponding to a certain specified line width d is the maximum value of the inclination of the straight line with the correction line width d ′ being d−i + 1. Is stored. The angle of the straight line is from 0 °
In the range of 45 °, the correction line width d ′ becomes maximum when the angle is 45 °, that is, the inclination is 1 according to the equation (2). Therefore, the last value in the table of slopes corresponding to each line width d is 1,
It will be 000.

The above is the table required for straight line drawing.

Now, the processing operation of GP24 performed using these tables will be described.

In the processing operation described above, first, the GP 24 derives the slope of a straight line from the coordinate values of the two designated points 55 and 56 stored in the attribute table (see FIG. 6A) in the SM 23.
Next, based on the value of the inclination of this straight line and the value of the designated line width d stored in the attribute table, the correction line width d ′ is used by using the line width correction table in SM23 (see FIG. 6 (c)). The value of is calculated as follows. That is, if the calculated slope value of the straight line is larger than the value of the i-1th row from the beginning of the column corresponding to the designated line width d and smaller than the value of the i-th row, the corrected line width d ′ is d ′.
= D-i + 1 can be calculated. For example, if the value of the slope of the straight line thus obtained is "0.800" and the designated line width d is "9", the sixth line
In the figure (c), the column corresponding to the designated line width "9" is 1 at the right end.
It is a column, and in that column, the value of the slope of the straight line “0.800” is
Since it is larger than the value "0.633" on the second line from the beginning and smaller than the value "0.958" on the third line, i is obtained as "3", and therefore,
Substituting into the formula: d ′ = d−i + 1 respectively, the correction line width d ′ is obtained as “7”.

Next, the above-mentioned processing operation will be described with reference to FIG.

FIG. 7 is an explanatory diagram for explaining the operation of obtaining the point sequence at the end of the straight line.

First, the GP24 is continuous from the designated point 55 in a direction perpendicular to the straight line, and the increment in the y-axis direction is [d '/ 2] (the symbol [] means integerization), that is, the correction line width. A point sequence having a length obtained by converting half of d'to an integer is obtained by DDA processing. In Fig. 7, the circle indicated by the dashed arrow is the DDA
It is the passing pixel obtained by the processing. Next, the GP 24 sets the point thus reached as the reference point 57, and performs the DDA processing on the point sequence whose increment in the y-axis direction from the reference point 57 toward the designated point 55 is the length of the correction line width d ′. Thus, as shown by the solid arrow in FIG. 7, the points are sequentially obtained to obtain a point sequence having the designated point 55 as the center. In FIG. 7, the pixels surrounded by a square are the obtained point sequences.

Next, GP24 uses the obtained point sequence as a deviation from the reference point 57.
Store in SM23. Specifically, if the straight line has an inclination of 0 ° to 45 °, the y coordinate of the obtained point sequence differs by 1 at every point, so the GP24 uses the absolute value of the deviation of the y coordinate value from the reference point 57. Is the index of the offset array 51 in the work table in the SM 23 (see FIG. 6 (b)), and the deviation of the x coordinate value from the reference point 57 is the offset array.
Store it at the location indicated by index 51. In the example of the straight line shown in FIG. 7, the offset array 51 has
It is stored in the order of φ, 1,1,2,2,3,3,4,4.

Next, the processing operation will be described, but before that, the DDA processing used in this embodiment will be described.

FIGS. 8A to 8C are explanatory views for explaining the unidirectional DDA method used for normal line drawing. In FIG. 8, circles represent pixels, and broken line 63 represents an ideal straight line. As shown in FIGS. 8 (a) and 8 (b), the unidirectional DDA is such that if the displacement from the ideal straight line to the center of the pixel is Δy, and when the next point is obtained from one point, if Δy is negative. In this method, the point 60 where the y coordinate is incremented by 1 along with the x coordinate is the next point, and the point 61 where the x coordinate is incremented by 1 is the next point if Δy is positive. The straight line drawn by this method is the 8th
It becomes like FIG.

FIGS. 8 (d) to 8 (f) are explanatory views for explaining the modified DDA in which the above-mentioned DDA is modified so that all regular voids formed inside a straight line having a width can be filled. It is a figure. When the next point is obtained from a certain point, the modified DDA draws the point 60, which is increased by 1 both in the x coordinate and the y coordinate, as the next point when Δy is negative, as shown in FIG. 8 (d). At the same time, it differs from the unidirectional DDA in that it also draws a point 62 that is incremented by 1 for the y coordinate. The straight line drawn by this method is as shown in FIG.

The above is the description of the DDA process.

Next, the above-mentioned processing operation will be described with reference to FIG.

FIG. 9 is an explanatory diagram for explaining an operation for obtaining a point sequence inside a straight line.

The GP24 performs unidirectional DDA processing from the reference point 57 to the other reference point 58 (how to obtain the reference point 58 will be described later), and the midpoint (x _n , y _n ) 70 are sequentially obtained. At this time, as shown in FIG. 9, the GP24 sequentially calculates the effective d ′ elements in the offset array 51 from the beginning to the end each time it finds one point (x _n , y _n ). Each coordinate value 71 of the point sequence with respect to the point (x _n , y _n ) 70 is obtained by subtracting the element index value from y _n and adding the offset value stored in the index to x _n ,
The point information is stored in the memory location in the FM 25 corresponding to those coordinate values 70 and 71. Further, at this time, by using the modified DDA method, point information is also written for points such as the pixel 62 shown in FIG. 8 (d) to eliminate the gap inside the straight line.

Next, the above-mentioned processing operation will be described with reference to FIG.

FIG. 10 is an explanatory diagram for explaining a processing operation for realizing the line style.

The attribute table in the SM 23 (see FIG. 6 (a)) is assumed to store a line pattern sequence 46 as shown in FIG. 10, and a pointer indicating the index of this array is also prepared. Be present.

Therefore, the GP24 starts from the reference point 57 as described in FIG.
When the point (x _n , y _n ) 70 is obtained by the unidirectional DDA method to 58, the contents of the array indicated by the pointer are taken out while incrementing the contents of the pointer of the array 46 shown in FIG. , Whether to draw the point with the coordinate value (x _n , y _n ) 70 and the point sequence with the coordinate value 71 obtained by referring to the offset value from the coordinate value (x _n , y _n ) 70 according to its contents Decide whether or not to write point information in FM25 to correspond to it. That is, if the content is φ, it means that the drawing is not performed as described above, and the point information corresponding to the meaning is stored in the FM25. If the content is 1, the point corresponding to the meaning of drawing is stored. Information is stored. After the pointer of the array 46 indicates the end of the array, the pointer of the array 46 cyclically indicates the beginning of the array.

The above is the description of the processing operation by the GP24. Next, such a processing operation will be further described in accordance with the processing procedure using the flowchart shown in FIG.

A program for realizing the above-described processing operation is usually stored on the SM 23, and the GP 24 interprets and executes the program to draw a straight line having a predetermined line width.

FIG. 1A is a flowchart showing the processing procedure of GP24.

The outline of the processing procedure by GP24 is as shown in FIG. That is, first, when the line width d is 2 or more, the subroutine compensate-winth130 is called to obtain the corrected line width d '(block 103). Then the subroutine find
Call edge140 to determine the offset array 51 (block 104). Finally, the subroutine draw-line150 is called to actually draw a straight line (block 105).

FIG. 1B is a flowchart showing a detailed processing procedure of the subroutine compensate-width 130. As shown in FIG. 1 (b), the GP24 first obtains the slope of a straight line from the ratio of the difference between the x coordinate and the y coordinate of two designated points stored in the attribute table in the SM23 (block 131). , Then SM23
For the line width correction table (see FIG. 6 (c)), the start address of the line width correction table for the specified line width d is obtained, and this is set as φ of the index (block 13).
2). Then, the GP24 sequentially reads the contents of the corresponding table while advancing the index one by one, and compares the contents with the obtained slope of the straight line (block 134). The corrected line width d'is obtained by subtracting the index value from d (block 136).

FIG. 1C is a flowchart showing the detailed processing procedure of the subroutine find-edge140.

In this subroutine, the GP 24 first performs dot expansion by DDA by a distance such that the increment in the y-axis direction is d '/ 2 from the designated point 55 in the direction perpendicular to the straight line, as described with reference to FIG. 7 (block 142). ~ 144), and the reached point is used as the reference point 57 (block 145). Next, the GP 24 performs dot development by DDA in the direction from the reference point 57 to the return designated point 55 by a distance such that the increment in the y-axis direction is d ′ (blocks 147 to 14).
9), the reference point 5
The displacement of the 7 from the x coordinate is stored in the offset array 51 in the work table in the SM 23 (block 148).
Next, the GP 24 obtains the coordinates of the reference point 58 at the other end by adding the deviation of the reference point 57 from the designated point 55 to the designated point 56 (block 146).

FIG. 1D is a flow chart showing the detailed processing procedure of the subroutine draw-line 150.

In the subroutine shown in FIG. 1 (d),
"Drawing a point" means that the GP24 writes point information, which means drawing, at a memory location in the FM25 corresponding to the coordinate value of that point.

As shown in Fig. 1 (d), the GP24 has a reference point 57 to a reference point.
DDA is performed toward 58 to sequentially obtain points (x _n , y _n ) 70 (block 152). Then, the GP24 cyclically looks at the line pattern sequence 46 stored in the attribute table in the SM24 (blocks 153 to 155) every time the DDA is advanced by one pixel, and if the corresponding array element is φ, nothing is drawn. If 1, the dots are drawn as shown below.

First, the GP24 draws a point (x _n , y _n ) 70 represented by a double circle in FIG.
From the beginning to the end of the offset array 51 stored in the table, the index value is subtracted from y _n, and the contents of the array 51 indicated by the index are added to x _n
Are sequentially obtained, and the point 71 is drawn (blocks 158 to 16).
2). In FIG. 9, the dot sequence to be drawn is represented by a square.

In addition, in order to eliminate the points that are not filled inside,
According to the modified DDA, the GP24 has a negative y coordinate deviation Δy from the ideal straight line at the previous point (x _n-1 , y _n-1 ) as shown in FIG. Then, a point such as a point 62 is drawn together with the next point 60 (block 160), and if Δy is positive, only the next point 61 is drawn as shown in FIG. 8 (e) (block 161).

The above is the description of the processing operation by the GP 24 according to the processing procedure.

According to the present embodiment, it is possible to draw a straight line having a uniform line width on both sides of a straight line connecting two specified points and having a specified line width and a specified line style. Further, in this embodiment,
Unlike the conventional method shown in FIG. 11 (c), no complicated calculation is required when obtaining the point sequences at both ends of a straight line, and DDA is performed when obtaining the offset array 51, and any other line is used. Since the DDA can be drawn on a straight line once, the DDA can be drawn at a higher speed than a method of repeatedly drawing the DDA the number of times corresponding to the line width as in the method shown in FIG. 11 (c).

Even when a straight line having a width that is not equal on both sides is drawn, for example, when a straight line having a line width on only one side of two specified points is drawn, when a point sequence at one end of the straight line is obtained. It is only necessary to obtain a series of points from one designated point in the direction perpendicular to the direction of the straight line, and there is no need to change the subsequent processing operation.

〔The invention's effect〕

According to the present invention, the following effects are obtained when drawing a straight line having a line width between two designated points.

For both ends of the straight line and the direction of the line style,
It is possible to draw a straight line that is cut in the vertical direction and that does not cause the omission of the fill inside the straight line.

Since a point sequence of straight lines connecting both ends only once is obtained for a straight line with an arbitrary width, a straight line can be drawn at a higher speed than a drawing method using multiple lines.

A straight line having a uniform width can be drawn on both sides of the straight line connecting the designated points.

[Brief description of drawings]

1 (a) to 1 (d) are flowcharts showing the processing procedure of the graphic processing device according to the present invention, FIG. 2 is a block diagram showing the configuration of the graphic device used for carrying out the present invention, and FIG. 2 is a block diagram showing the configuration of the graphic processing unit of FIG. 4, FIG. 4 is a schematic diagram showing an example of screen output by the straight line drawing method of the present invention, and FIG. 5 is a diagram showing the relationship between the designated line width and the correction line width. Explanatory diagram, FIG. 6 is a schematic diagram showing a table necessary for drawing a straight line in the present invention, FIG. 7 is an explanatory diagram for explaining an operation for obtaining a point sequence at the end of a straight line in the present invention, and FIG. Is an explanatory view for explaining the DAA processing used in the present invention, FIG. 9 is an explanatory view for explaining an operation for obtaining a point sequence inside a straight line in the present invention, and FIG. 10 is a line style in the present invention. To realize FIGS. 11A to 11C are explanatory diagrams for explaining the conventional straight line drawing method, and FIG. 12 is a method for obtaining the four corners of the straight line in the conventional method. FIG. Reference numeral 22 ... Raster display 23 ... Segment memory 24 ... Graphic processor 25 ... Display memory 26 ... Display controller 46 ... Line pattern row, 51 ... Offset array 55,56 ... Specified point, 57, 58 ... Reference point

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoya Ikeda 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Microelectronics Equipment Development Laboratory (72) Inventor Yoshihiro Yokoyama Totsuka-ku, Yokohama-shi, Kanagawa 292 Yoshida-cho, Hitachi, Ltd. Microelectronics Equipment Development Laboratory (56) Reference JP-A-57-159389 (JP, A) JP-A-59-29293 (JP, A) JP-A-59-136784 (JP, A)

Claims (2)

[Claims] 1. An input device, a processing device, a main memory, a raster display, a display memory, and a display control device. The processing device is stored in the main memory according to an instruction from the input device. After extracting and processing the desired graphic data, and storing in the area on the display memory corresponding to the pixels on the screen of the raster display,
In a graphic device in which the display control device reads out data stored from the display memory and displays it as an image on a screen of the raster display, a straight line having a predetermined line width is displayed on the raster display by the input device. When instructed to do so, the processing device obtains a parameter defining the straight line from the main memory in accordance with a program stored in the main memory, and from the parameter, the processing unit determines a parameter perpendicular to the direction of the straight line at one end of the straight line. Each point coordinate of the first point sequence that is continuous in the direction and has a length equal to the line width is obtained, and one point in the first point sequence is used as a first reference point, and the other with respect to the first reference point. After storing the relative position coordinates of each point in the memory in the memory, a second reference point corresponding to the first reference point at the other end of the straight line and the first base point are stored. The coordinates of each point of the second series of points connected to the line connecting the points are obtained, and each time the point coordinates are obtained, the point is referred to with reference to the relative position coordinates also stored in the main memory. When the point coordinates of the relative point existing at each relative position based on each of the position coordinates with respect to are obtained respectively and the point coordinates of the relative point are obtained, both the x coordinate value and the y coordinate value of two adjacent relative points are obtained. , The x coordinate value is the same as one of the two relative points and the y coordinate value is the same as the other relative point, or one of the two relative points. And the y coordinate value are the same, and the other relative point and the point having the same x coordinate value are also obtained, and predetermined point information is respectively stored in the memory position in the display memory corresponding to the obtained coordinate position of each point coordinate. Store and then display control device A straight line in a graphic device, wherein the stored point information is read out and displayed on the screen of the raster display to draw a straight line having a predetermined line width on the screen of the raster display. Drawing method. 2. The straight line drawing method according to claim 1, wherein the parameters defining the straight line specify the point coordinates of two specified points that specify the drawing position of the straight line and the line width of the straight line. When the processing device obtains the first point sequence from the parameter, the processing device includes
From the coordinate position of one of the two designated points, the point sequence is sequentially obtained in the direction perpendicular to the direction of the straight line by the number corresponding to the half of the designated line width, and the reached point is the first point. The reference point is defined as a reference point, and a sequence of points is sequentially obtained from the reference point in the direction of the designated point by a number corresponding to the distance of the designated line width, and the obtained sequence of points is set as the first sequence of points. A straight line drawing method in a characteristic graphic device.