JPH0378888A - Graphic data processor - Google Patents

Abstract

PURPOSE:To shorten processing time required for determining a dividing number and to attain the high speed of graphic processing including the curve processing of a polygonal line by calculating a distance on a straight line, for which a curve is approximated, and calculating the dividing number of the curve. CONSTITUTION:A graphic processing part 4 is equipped with a curve processing part 5 to execute processing to curve the polygonal line, and the curve processing part 5 is composed of a curve dividing part 7, which further determines a mid point between the end points of the curve and calculates the dividing number of the midpoint of the curve, and a curve calculating part 6 to calculate a curve equation and to calculate the coordinates of a point dividing the curve. When the polygonal is curved, at first, the midpoint between the both ends parts is calculated on the curve by the curve equation and the dividing number is determined according to the linear distance between the both end points and the midpoint. Next, the curve between the end point is divided by the dividing number and the coordinates of the dividing point are calculated. Thus, the time required for the curve processing of the polygonal line can be shortened.

Description

[Detailed Description of the Invention] (Summary) This invention relates to a graphic data processing device that sets an equation for curving a polygonal line in order to process the polygonal line into a curve, and displays a figure obtained by the curve processing on a display. For the purpose of shortening the processing time required to curve a polygonal line in , the polygonal line consisting of points A, B, and C, with point A1 and point C as the end points, and point B as the apex, is to be curved. a curve calculation unit that calculates a curving equation that gives a curve passing through two end points A and C;
Find one intermediate point on the above curve with the above two points A and C as the end points, and depending on the length of each straight line distance from the end points A and C,
a curve dividing section that determines the number of divisions into which the curve is to be divided with points A and C as end points, and the curve calculation section determines points A and C as end points based on the number of divisions determined by the curve dividing section. It has a configuration that calculates the coordinates of dividing points on the above curve.

[Industrial application field]

The present invention relates to a graphical data processing device having a function of converting a polygonal line into a curve, and more particularly, to a graphical data processing device that curves any polygonal line according to a curving equation and displays the curved line on a display.

[Conventional technology]

In conventional graphic data processing devices, when displaying a polygonal line as a curve, a curve equation for a spline curve, etc. is calculated using the coordinates of both end points and apex of the polygonal line, and the coordinates of a series of points on the curve are determined. To create a series of points on this curve (referred to as dividing points here), first find the length of the arc of the curve at both end points, then determine the number of divisions according to the length of the arc.
The seat of the dividing point! It can be obtained by finding 1. Thereafter, the coordinates of the dividing points are connected with straight lines to display a curved figure.

A conventional curve processing method will be specifically explained with reference to FIGS. 6 and 7.

FIGS. 6(1), (2), and (3) are explanatory diagrams of the conventional curve processing method.

In FIG. 6(1), a polygonal line ABC consisting of endpoints A and C and vertex B is the polygonal line to be curved.

The curve formation is performed by calculating an equation for curve formation such as a spline curve according to the coordinate data of points A, B, and C.

L in FIG. 6(2) is a curve calculated in this way, and although it has not been calculated yet at this stage, it is shown hypothetically for convenience.

In Figure 6 (2), the distance W of the arc length AC of the curve to be found
12 is calculated using the integral calculation formula derived from the curve equation, and the distance @1. Based on the arc length AC1, that is, the end point A,
The number of divisions n of the curve between C is determined. Then, the coordinates of each dividing point on the curved line divided by the number of divisions n are determined using a curve forming equation.

In FIG. 6 (3), points tl, t2...tn are
A point on the coordinates of the division point obtained is L.

is a curved figure of a polygonal line ABC connecting the dividing points, and this figure is displayed on the display.

FIG. 7 shows a flowchart of the procedure of the conventional curve processing method described above.

[Problem to be solved by the invention]

Conventionally, the distance on the curve between the end points of the curve as described above was determined by integral calculation, and the number of divisions was determined based on the length, which required a long time for calculation processing.

SUMMARY OF THE INVENTION An object of the present invention is to shorten the time required for curve processing of polygonal lines in a graphic data processing device.

[Means to solve the problem]

In the present invention, the procedure for determining the number of divisions is a method that does not use integral calculations. Therefore, when converting a polygonal line into a curve, first, the middle point between both end points is placed on the curve using a curving equation. The number of divisions is determined by the straight-line distance between both endpoints and the middle point.

Then, the curve between the end points is divided according to the number of divisions, and the coordinates of the dividing points are calculated.

The principle of the present invention will be explained with reference to the basic configuration diagram shown in FIG.

In FIG. 1, 1 is a mouse, 2 is a keyboard, and 3 is a graphic data input section. 4 is a graphic processing unit that processes input graphics. The graphic processing unit 4 includes a curve processing unit 5 that performs processing to curve a polygonal line, and the curve processing unit 5 further determines an intermediate point between the end points of the curve and calculates the number of divisions at the intermediate point of the curve. The curve dividing section 7 calculates a curve forming equation to obtain the coordinates of the points at which the curve is divided. Reference numeral 8 denotes a display unit equipped with a display device 9 and the like for displaying a curved line based on the coordinates of the dividing points.

The flow of the polygonal line curve processing in the graphic processing section 4 in the basic configuration of the present invention is as follows.

■ Calculate curve data using the curve equation of polygonal line ABC.

■ Determine the midpoint M on the curve between endpoints A and C.

■ Determine the number of divisions based on the straight-line distance between the endpoints A and C and the midpoint M.

■ Divide the curve by the determined number of divisions and find the coordinates of the division points.

[Effect]

The operation of the above basic configuration will be explained with reference to FIG.

In Figure 2 (1), the polygonal line represented by ABC is A
, is a curved line with C as the end point and B as the apex.

First, in the curve processing unit 5 in FIG. 1, an equation for curve formation passing through at least end points A and C is set.

The curving equation may be determined so that the solution curve passes through vertex B.

Next, in the curve dividing section 7 in FIG. 1, as shown in 2) in FIG. 2, an intermediate point M that satisfies the curve forming equation is found between both end points A and C. Furthermore, the curve dividing portion 7 is a straight line A
The lengths 11 and ε2 of M and CM are calculated, and the numbers of divisions nl and n2 of each straight line are determined at predetermined degrees according to the lengths of straight lines AM and CM.

Next, the curve calculation unit 6 in FIG. 1 calculates the number of divisions n1, n
2, calculate the coordinates of each dividing point that divides the curve between end points A and C.

As a result, the display section 8 in FIG. 1 displays the coordinate points sl, . . . snl based on the coordinate data obtained by the curve calculation section 6, as shown in FIG. 2 (3).

Connect tl, ...tn2, with a straight line to create a polygonal line ABC
The curved figure is displayed on the display device 9.

According to the present invention, dividing points of a curve are determined by determining the distance on a straight line that approximates the curve, instead of determining the length of the arc of the curve by integral calculation as in conventional graphic data processing devices. Therefore, the processing time for converting a polygonal line into a curve can be shortened.

〔Example〕

The present invention will be explained in detail with reference to FIGS. 3 to 5.

Note that FIG. 1 is referred to as necessary.

In FIG. 3(1), a polygonal line ABC is a polygonal line to be curved. When the midpoints of line segments AB and BC are x and Y, respectively, the curved line is AX.

This is a case where CY can be approximated by a straight line.

First, an equation for converting the polygonal line ABC into a curve is set in the curve processing unit 5 shown in FIG.

Next, the curve dividing section 7 in FIG. 1 calculates the coordinates of the midpoints X and Y of the line segment AB and the line segment BC, as shown in FIG. 3 (2).

Subsequently, the curve dividing section 7 is
, midpoint M of the curve that satisfies the curving equation with Y as the end point
, and calculate the length of the sum of line segment XM and line segment YM. The curve dividing section 7 determines the number of divisions n based on the degree of the sum XM+YMO value of the line segments XM and YM.

Next, the curve calculating section 6 calculates the coordinates of successive dividing points of the curve that satisfy the curve forming equation using the number of divisions n, with X and Y as the end points.

The display section 8 in FIG. 1 is between A and Y.

A straight line connects C and Y and the coordinates determined by the curve calculation unit 6, and a curved figure of the polygonal line ABC is displayed on the display device 9.
Display above.

FIG. 4 is a flowchart of an embodiment of the curve forming process of the present invention.

The flow will be explained according to the diagram.

■ Define the equation to curve the polygonal line ABC.

■ Find the midpoint X of line segment AB.

■ Find the midpoint Y of the line segment BC.

(2) Find the midpoint M on the curve that satisfies the curving equation with X and Y as the end points and B as the vertex.

■ Find the sum of the lengths of line segments XM and YM.

■ Find the number of divisions corresponding to the value found in step (■). Calculate the coordinates of the division points that divide the curve using the number of divisions found in step (2).

A straight line connecting the coordinate points obtained through the above processing is output on the display and displayed as a curve.

FIG. 5 shows an example of a method for determining the intermediate point M.

The intermediate point M is determined at a position that is easy to calculate and is as close to a straight line as possible.

FIG. 5(1) shows a case where the intersection point of the curved line and the median line connecting the midpoint of the line segment AC and the vertex B is selected as the intermediate point M.

FIG. 5(2) shows a case where the intersection of the bisector of angle ABC and the curved line is set as the intermediate point M.

In addition, the intersection point between the vertex B and the perpendicular to the line segment AC can be selected at a position that is easy to calculate based on the function of the isocurve.

In the above embodiment, the number of divisions of a curve can be easily obtained by simply calculating the distances between straight lines XM and YM, and
Since only the midpoints X and Y of C are curved, the number of dividing points is small, and the lengths of the line segments AM and CM are calculated by finding the midpoint M on the curve with the end points at points A and C. The curve processing time can be reduced compared to the case where

〔Effect of the invention〕

According to the present invention, when converting a polygonal line into a curve, the length of the arc of the curve is not determined by integral calculation as in conventional graphic data processing devices, but by determining the distance on a straight line that approximates the curve. Since the number of divisions of the curve is determined, the processing time required for determining the number of divisions can be significantly shortened, and graphic processing including curve processing of polygonal lines can be sped up.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the present invention. FIG. 2 is an explanatory diagram of the operation of the basic configuration of the present invention. FIG. 3 is a diagram showing an embodiment of the curve forming process of the present invention, and FIG. 4 is a flow diagram of the embodiment of the curve forming process of the present invention. FIG. 5 is a diagram showing an embodiment of the method for determining the intermediate point M of the present invention. FIG. 6 shows a conventional curve processing method. FIG. 7 is a flow diagram of conventional curve forming processing time. In FIG. 1, 3: Graphic data input section, 4: Graphic processing section, 5: Curve processing section, 6: Curve calculation section, 7: Curve division section, 8: Display section, lO bicurve division processing figure.

Claims (2)

[Claims] (1) In a graphic data processing device that has the function of displaying a polygonal line or polygon of input data as a curve, a polygonal line consisting of points A, B, and C, with point A and point C as the end points and point B as the apex. In order to curve, at least the above 2
A curve calculation unit 6 calculates a curve forming equation that gives a curve passing through the two end points A and C, and a curve calculation unit 6 that calculates an intermediate point on the curve having the two end points A and C as the end points, and calculates an intermediate point between the intermediate point and the end point A.
, and a curve dividing unit 7 that determines the number of divisions into which the curve with end points A and C is divided according to the length of each straight line distance between the points A and C, the number of divisions determined by the curve dividing unit 7. A graphic data processing device characterized in that the curve calculating section 6 calculates coordinates of dividing points on the curve having points A and C as end points based on the above. (2) In claim (1), line segment @AB@, line segment @B
Find the midpoints X and Y of each line segment on C@, and
A graphic data processing device characterized in that a polygonal line XBY having an end point of XBY and a point B of an apex is turned into a curve.