JP3089740B2 - Line drawing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line drawing apparatus for drawing a line.

[0002]

2. Description of the Related Art Conventionally, in graphic processing such as a word processor, an arbitrary curve pattern is drawn according to a freehand method using input means such as a cursor key. For example, as shown in FIG. Also, when a new curve RS parallel to the set curve PQ is kept at a constant interval a, a new curve RS is drawn in accordance with a freehand method using a cursor key or the like.

[0003]

By the way, two parallel
When drawing two straight lines, one line segment is drawn according to the freehand method, and then this line segment is copied and the other line segment is drawn, so that two parallel straight lines, etc., are drawn. Can be obtained accurately, but the method of drawing two parallel line segments by copying is limited to relatively simple line segments such as straight lines. For this reason, as shown in FIG. 6, when drawing a curve RS parallel to a curve PQ having a complicated shape at a constant interval a, the curve PQ is drawn according to the freehand method. It has been extremely difficult to draw line segments according to the freehand method. An object of the present invention is to make it possible to automatically draw a line segment having a constant distance interval with respect to a curved line segment having a different degree of curve at each position already drawn. is there.

[0004]

In order to achieve the above object, a line segment drawing apparatus according to the present invention comprises a display means for displaying curved line segments having different degrees of curve at respective positions, and a parallel curve for the curved line segments. Instructing means for instructing the drawing of a line segment, and a plurality of points on the curved line segment which are orthogonal to a tangent passing through each coordinate position of the plurality of points on the curved line segment, based on the drawing instruction by the instructing means. Coordinate position determining means for determining, for each of the normals, the coordinate position of a point on each of the normals and at a predetermined distance from the curved line segment. And drawing means for drawing parallel curve line segments maintaining the predetermined distance interval with respect to the curve line segments by combining the coordinate positions obtained by the coordinate position determination means. Characterized by .

[0005]

[Description of Functional Block Diagram] FIG. 1 is a functional block diagram of the present invention. The interval designating means 1 is used for the first drawing which has already been drawn.
When newly drawing a second line segment parallel to the line segment, the first line segment already drawn and the second
Specify the interval with the line segment. In this case, the start point of the line to be newly drawn may be point-designated by using a cursor key or the like. The line segment analyzing means 2 analyzes the shape of the first line segment already drawn. The drawing unit 3 draws a second line segment while keeping a constant interval with respect to the first line segment based on the analysis result of the line segment analyzing unit 2 and the interval specified by the interval specifying unit 1.

[0006]

An embodiment will be described below with reference to FIGS. FIG. 2 is a block diagram showing the configuration of the line segment drawing apparatus. The CPU 11 controls the overall operation of the line drawing apparatus according to various programs.
Document data and graphic data input from
The data is output from the CRT display device 14 via the M (VRAM) 13 or written into the input buffer 15 and then stored in the text memory 16. Here, when a registration key (not shown) on the key input unit 12 is operated, the contents of the text memory 16 are registered and stored in the external storage device 17.

Particularly, in this embodiment, the CPU 11 is connected to a distance calculating circuit 18, a line segment analyzing circuit 19, a drawing pixel calculating circuit 20, and a drawing circuit 21. Distance calculation circuit 1
Reference numeral 8 denotes a circuit for calculating the distance between the start point of the already drawn line segment and the start point of the newly drawn line segment when drawing a new line segment parallel to the already drawn line segment. The line segment analyzing circuit 19 analyzes a shape (pixel) of a line segment already drawn, and the drawing pixel calculating circuit 20 generates a new line segment from the contents obtained by the distance calculating circuit 18 and the line segment analyzing circuit 19. A circuit for obtaining a pixel for drawing, a drawing circuit 21 draws the pixel obtained by the drawing pixel calculation circuit 20 as a drawing point, and draws a line segment connecting the previously drawn point and the currently drawn point. Circuit.

Next, the operation of this embodiment will be described. Now
It is assumed that a curve PQ as shown in FIG. 4 is drawn on the CRT display device 14. Here, when drawing a new curve parallel to the curve PQ, a parallel drawing key (not shown) on the key input unit 12 is operated. Then, the parallel drawing process is executed according to the flowchart of FIG. First, when the start point R of a newly drawn curve is designated by a cursor key or the like (step S1), the distance calculation circuit 18 determines the start point P of the already drawn curve PQ and the start point R of the newly drawn curve. And the distance A of
Distance from this distance A on the normal passing through point P (drawing distance) a
Is obtained (step S2).

Next, the line analysis circuit 19 sets the main points (pixels) from the start point to the end point on the already drawn curve PQ as P ₀ , P ₁ , P ₂ ... Two matching points P _n and P _{n + 1} (n = 0, 1, 2,...) Are obtained (step S3). At first, P ₀ and P ₁ are obtained as two points (see FIG. 5). The segment analysis circuit 19 obtains a straight line (tangent) f ₁ through the P _0, P ₁ the two points (step S4), and perpendicular to the tangent f _1, two points P _0, P
_A normal g1 passing through the center of ₁ is obtained (step S5).

On the normal line g ₁ thus obtained, the drawing pixel calculation circuit 20 obtains position coordinates at a drawing distance a from the center of the points P ₀ and P ₁ (step S 6), and this is newly drawn. This is the first pixel _R0 to be performed. Next, the drawing circuit 21 connects the pixel R _n obtained in this way and the pixel R _n-1 obtained last time with a straight line (step S7). When the first pixel R ₀ is obtained, step S7 is performed. Skipping is performed, the process proceeds to step S8, and it is determined whether or not all the new line segments have been drawn up to the end point.

As a result, the tangent f passing through the points P ₁ and P ₂
Perpendicular to _2, normal g ₂ a determined (step S5) passing through the center of the points P _1, P _2, obtains the pixel R ₁ with a distance a on the normal line g ₂ (step S6). Then, combine the pixel R ₀ determined pixel R ₁ and the previous obtained this time in a straight line (step S7).

[0012] Hereinafter, the point P _n by repeating the same operation as described above, and perpendicular to the normal line f _n through P n _{+ 1,} the point P _n, P
Pixels R _n and R _n−1 are combined while obtaining a pixel R _n separated by a distance a on a normal g _n passing through the center of _{n + 1} . As a result, a new curve is drawn at a distance a from the already drawn curve PQ, and a curve parallel to the curve PQ is automatically drawn.

The type of the already drawn curve (solid line, broken line, thick line, thin line, etc.) is determined, and a line type similar to the line type of the curve is automatically selected to draw a new curve. You may do so.

[0014]

According to the present invention, based on a drawing instruction, a plurality of points on a curved line segment having different degrees of curve at respective positions are orthogonal to tangents passing through respective coordinate positions,
A normal passing between two adjacent points among the plurality of points on the curved line segment is obtained, and the coordinate position of a point on the individual normal line and at a predetermined distance from the curved line segment is determined by each normal line. By calculating each coordinate position and combining the obtained coordinate positions, a parallel curved line segment that keeps a predetermined distance interval with respect to the curved line segment having a different curve degree at each position is drawn. Therefore, even for a curved line segment having a complicated shape, it is possible to automatically draw a line segment maintaining a predetermined distance interval from the curved line segment. In particular, when a large number of roads are drawn on a map, a large number of curve curves having a constant width can be efficiently drawn.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of the present invention.

FIG. 2 is a block diagram of a line segment drawing apparatus showing an embodiment.

FIG. 3 is a flowchart for explaining the operation of the embodiment.

FIG. 4 is a diagram showing a drawing distance a calculated by designating a start point R of a new line segment when drawing a new line segment parallel to a line segment already drawn;

FIG. 5 is a diagram showing a state in which a new line segment is drawn by analyzing a line segment already drawn.

FIG. 6 is a diagram for explaining a conventional example, showing parallel curves.

[Explanation of symbols]

 Reference Signs List 11 CPU 12 Key input unit 13 VRAM 14 CRT display device 18 Distance calculation circuit 19 Line segment analysis circuit 20 Drawing pixel calculation circuit 21 Drawing circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G06T 11/20

Claims (1)

(57) [Claims] 1. The degree of curve differs at each position.
Display means for displaying a curved line segment; instructing means for instructing drawing of a parallel curved line segment with respect to the curved line segment; and coordinates of a plurality of points on the curved line segment based on a drawing instruction by the instructing means. Perpendicular to the tangent passing through the position,
Two adjacent points among a plurality of points on the curved line segment
A coordinate position determining means for determining, for each of the normals, a coordinate position of a point which is located at a predetermined distance from the curved line segment on each of the normal lines and which determines a normal line passing between the points; By combining the coordinate positions obtained by the means, the distance between the curved line segment and the predetermined distance
Drawing means for drawing a parallel curved line segment keeping a distance, a line segment drawing device comprising: