JPH03250270A - Elliptical drawing system - Google Patents

Abstract

PURPOSE:To always draw an ellipse with high quality by calculating difference between respective coordinates on a true circle and respective coordinates of the ellipse calculated from the true circle, and calculating coordinates perpendicularly positioning to the tangential direction of respective points on the ellipse so as to draw a straight line with prescribed width from the respective coordinates of the ellipse based on the change rate of this difference. CONSTITUTION:Difference dy' between coordinate data (X1,Y1) of the true circle and coordinate data (X1',Y1') of the ellipse is calculated for each coordinate data. Based on this difference, the straight line is drawn while calculating the coordinate data (X1',Y1') so as to draw the straight line for width (t) of the line on the inside from the coordinate data of the ellipse. Therefore, on the display of a display device 5 or on the recording sheet of a printer 6, the ellipse can be drawn with the line of the width (t) perpendicularly to the tangential direction of the ellipse. Thus, the ellipse with high quality can be always drawn with the fixed line width.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ellipse drawing method, and more particularly to an ellipse drawing method that equalizes the thickness of lines when drawing an ellipse using lines of a predetermined thickness.

(Prior art) Conventional ellipse drawing methods, for example, aim to draw with a uniform thickness, and generate an ellipse based on the ratio of the major axis to the minor axis of each coordinate of a perfect circle whose radius is the major axis. There is a way to draw. In this method, when drawing an ellipse with a thickness of 2 dots or more, when calculating the ellipse from a perfect circle, draw a line equal to the thickness in the vertical or horizontal direction from each coordinate of the calculated ellipse. Draws an ellipse of dots.

The branching point of whether to draw a straight line in the vertical direction or in the horizontal direction is a point (first quadrant) where 456 straight lines tangent to each coordinate data of the ellipse form, as shown in FIG.

(Intelligence to be Solved by the Invention) However, in such a conventional ellipse drawing method, when drawing an ellipse with a line of a predetermined thickness, at the branch point between the vertical direction and the horizontal direction, as shown in FIG. As shown, overlapping portions of straight lines occur, causing a problem in which logical operations cannot be performed during drawing. Another problem is that the lines drawn at the vertical and horizontal branching points become thinner, making it impossible to draw an ellipse with a uniform line thickness.

Furthermore, when drawing an ellipse using a pattern such as a dotted line, the dotted line can only be drawn in the vertical and horizontal directions, so only poor quality ellipses can be drawn.

(Object of the Invention) Therefore, the present invention calculates the difference between each coordinate on a perfect circle and each coordinate of an ellipse obtained from the perfect circle, and calculates the difference between each coordinate of the ellipse based on the rate of change of the difference. By determining the coordinates perpendicular to the tangential direction of each point on the ellipse for drawing a straight line of a predetermined thickness, it is possible to draw an ellipse of uniform thickness, resulting in a high-quality ellipse. The purpose is to provide an ellipse drawing method that can be used to draw ellipses.

(Structure of the Invention) In order to achieve the above object, the present invention calculates coordinate data forming a perfect circle that is tangent to the major axis direction based on input center coordinate data, major axis and minor axis data, and Obtaining coordinate data forming an ellipse from the coordinate data forming the axis and the ratio of the major axis to the minor axis, and drawing the ellipse,
In this ellipse drawing method, when drawing the ellipse with a line of a predetermined thickness, the ellipse is drawn by drawing a straight line of the predetermined thickness perpendicular to the tangent direction of each point on the ellipse from coordinate data on the ellipse. a difference calculation means for calculating a difference between each coordinate data of the perfect circle and each coordinate data of the ellipse; The present invention is characterized in that it includes a coordinate calculation means for calculating coordinate data perpendicular to the tangential direction of each point on the ellipse.

Hereinafter, the present invention will be specifically explained based on examples.

1 to 5 are diagrams showing an embodiment of the present invention, which is applied to a word processing sensor.

FIG. 1 is a block diagram of the Food Pro Sensor 1, and the word processor 1 includes an input device 2, a central processing unit 3,
It is composed of a storage device 4, a display device 5, a printing device 6, and the like.

The input device 2 is equipped with a numeric keypad, various function keys, etc., and inputs text data, data for drawing an ellipse (to be described later), etc. to the central processing unit 3.

As shown in FIG. 2, the central processing unit 3 has memories 11 to 1.
4, perfect circle generator 15, computing units 16 to 18, straight line generator 1
9. Pattern generator 20 and page buffer 2
It consists of 1st class. The memory 11 stores data for drawing an ellipse input from the input device 2, and outputs the stored data to the perfect circle generator 15 and the arithmetic unit 18.

The perfect circle generator 15 calculates coordinate data for forming a perfect circle based on the data for drawing an ellipse inputted from the memory 11, and outputs it to the calculation units 16-18. A computing unit (difference computing means) 16 computes the distance jWdy' (difference in the Y-axis direction) between the coordinate data of the ellipse and the coordinate data of the perfect circle based on the coordinate data of the perfect circle, and stores the result in the memory 12. The arithmetic unit 17 calculates the coordinate data of the ellipse based on the coordinate data of the perfect circle and outputs the result to the memory 13.

The distance Mdy data stored in the memory 12 is output to the calculator 18, and the ellipse coordinate data stored in the memo January 3 is output to the calculator 18 and the straight line generator 19. A computing unit (coordinate computing means) 18 receives ellipse drawing data input from the memo January 1, perfect circle coordinate data input from the perfect circle generator 15, distance 11dy input from memory 2 and memory 1.
Based on the coordinate data of the ellipse input from 3, calculate the coordinate data (coordinate data for drawing the ellipse with a line of a predetermined thickness) inside the ellipse, which will be described later, and output the result to Memo January 4. . The coordinate data stored in the memory 14 is output to a straight line generator 19.

The straight line generator 19 is a page buffer that writes data for drawing a straight line to the page buffer 21 according to the output of the pattern generator 20 based on the coordinate data of the ellipse inputted from the memory 13 and the coordinate data inputted from the memory 14. The data written in 21 is output to the display device 5 or printing device 6, and an ellipse is drawn on the display or recording paper. Storage device 4
has an area for storing text data input from the input device 2 and results of calculations performed by the central processing unit 3.

Next, the effect will be explained.

In this embodiment, the process for drawing an ellipse as shown in FIG. 3 using a line of a predetermined thickness will be explained with reference to the flowchart shown in FIG. 4.

First, if the center coordinates, major axis Rh, minor axis Rν, and line thickness data t are input as data for drawing an ellipse from the input device 2 (step P1), the perfect circle generator 15 generates a perfect circle. Coordinate data (Xn,
Step P2) Next, the calculator 17 calculates the coordinate data (Xn') of the ellipse according to the following formula fl) and (2).
, Yn'), and the arithmetic unit 16 calculates the path 1'dy' according to the following equation (3) (Step 7, P3).

Xn =Xn (11Y
n' = Yn(e)Rv/Rh ・--(2)dy'
=Yn-Yn' ・-・(3) However, n=o~
Next, the calculator 18 calculates the coordinate data (Xn', Yn') inside the ellipse to draw a line of thickness t from the coordinate data of the ellipse obtained using equations (1) and (2) using the following equation (4). ,(5)
Calculation is performed according to (step P4).

Yn'→△yL, (dy-dy') ・t/dy
−・−−−(4)Xn′→Δx=FU:Kp
--------(5) Next, the arithmetic unit 12 and the arithmetic unit 13
After storing the results calculated in the memories 13 and 14, respectively, the linear generator I9 generates the coordinate data of the ellipse (Xn,
Yn) and the coordinate data inside the ellipse (Xn', Yn'
) to write data for drawing a straight line to the page buffer 21 and connect the two points with a straight line (Step P5)
. At this time, the signal output from the pattern generator 20 determines whether to draw a straight line with bit "0" or with bind pattern 1. Next, the processing of steps PI-P5 is completed for all coordinates. If the process has not been completed, the process returns to step P2 and continues to process the data for the next coordinate, repeating steps P2 to P5 until the process for all coordinates is completed.

Through the above processing, the coordinate data of a perfect circle (x,, Y,) and the coordinate data of an ellipse (x, as shown in FIG. 3) are obtained.

■, ') is calculated for each coordinate data, and based on this difference, the coordinate data (XI'
.

Therefore, it is possible to always draw a high-quality ellipse with a constant line thickness, and even if the ellipse is made up of a pattern such as dotted lines as shown in Figure 5, the tangential direction of the ellipse can be drawn in the same way. Since it is drawn with vertical straight lines, it can also be drawn with good quality.

(Effect) According to the present invention, the difference between each coordinate on a perfect circle and each coordinate of an ellipse obtained from the perfect circle is determined, and a predetermined thickness is determined from each coordinate of the ellipse based on the rate of change of the difference. Since we are calculating the coordinates perpendicular to the tangent direction of each point on the ellipse to draw a straight line, we can draw an ellipse of uniform thickness and always draw an ellipse of good quality. I can do that.

[Brief explanation of drawings]

1 to 5 are diagrams showing one embodiment of the ellipse drawing method according to the present invention. FIG. 1 is a block diagram of the overall configuration of a food processor that is compatible with the ellipse drawing method, and FIG. Figure 3 is a diagram showing an example of drawing the ellipse, Figure 4 is a flowchart showing the process for drawing the ellipse, and Figure 5 is a diagram showing the process for drawing the ellipse. It is a figure which shows an example of drawing. FIG. 6.7 is a diagram showing an example of drawing an ellipse using the conventional ellipse drawing method. 1...-Word processor sensor 2...Input device, 3...Central processing unit, 4...-Storage device, 5...Display device, 6--Printing device, 11-14...Memory, 15...Perfect circle generator, 16... Arithmetic unit (difference computing means) 17...
...Arithmetic unit, 18...Arithmetic unit (coordinate calculation means) 19...
... Linear generator, 20... Pattern generator, 21-...
...Page buffer. Substitute Patent Attorney Yugagun Figure Figure 1 Figure Figure Figure 1

Claims (1)

[Claims] Based on the input center coordinate data, major axis and minor axis data, calculate the coordinate data that forms a perfect circle that is tangent to the major axis direction, and calculate the ellipse from the coordinate data that forms the perfect circle and the ratio of the major axis and minor axis. At the same time, when drawing the ellipse with a line of a predetermined thickness, a straight line of the predetermined thickness is drawn perpendicular to the tangent direction of each point on the ellipse from the coordinate data on the ellipse. An ellipse drawing method for drawing an ellipse by drawing, the method comprising: a difference calculation means for calculating a difference between each coordinate data of the perfect circle and each coordinate data of the ellipse; coordinate calculation means for calculating coordinate data perpendicular to the tangential direction of each point on the ellipse for drawing a straight line of the predetermined thickness;
An ellipse drawing method characterized by the provision of .