JPH0785301A - Information processor - Google Patents

Abstract

PURPOSE:To provide an information processor which can specify a graphic at a high speed by reducing the objects of an on-line judgement processing. CONSTITUTION:When a designated point is inputted from an input means 1, a rectangle area calculation means 2 calculates two rectangle areas consisting of the designated points and four control points, and a first judgement means 3 judges whether the designated points are included in the rectangle areas or not. When the designatd points are included in the rectangle areas, a second judgement means 4 judges whether the designated points and a segment exist within prescribed distances or not. When they exist, a Bezier curve specification means 5 specifies a Bezier curve including the segment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing apparatus, and more particularly to an information processing apparatus having a Bezier curve drawing function.

[0002]

2. Description of the Related Art Personal computers, office computers, workstations, electronic publishing systems, word processors and other various information processing devices are used in offices,
Widely used in factories, design offices, homes, etc. When creating various drawings such as road maps and architectural drawings in such an information processing apparatus, it is necessary to draw a curve of an arbitrary shape, and as a method therefor, a Bezier curve using a Bezier function may be used. . The Bezier curve is drawn by four control points, and is a curve that passes over the start point and the end point and passes inside two control points designated between them.

On the other hand, in the information processing apparatus having such various graphic processing functions, it is necessary to perform a process of specifying a predetermined graphic that has already been created. For example, when performing various processes such as deleting, moving, copying, and transforming an already created figure, the figure specifying process described below is performed. First, the operator moves a cursor on a Bezier curve to be specified among a plurality of Bezier curves displayed on the display and inputs a designated point. Then, the information processing device recognizes the Bezier curve on this designated point. For recognition, it is determined whether or not there is a designated point in a predetermined region including the Bezier curve, and if it is included in the region, it is further determined whether or not there is a designated point on the Bezier curve. Make a linear decision. Here, the line determination is
Repeatedly divide the segment (the smallest unit Bezier curve between the input anchor points) and approximate it with a straight line connecting each anchor point, and for each straight line, whether the specified point is included in the rectangular area containing the straight line To judge. If the designated point is included, the distance between the designated point and the straight line is calculated, and if it is within the allowable range, it is determined that the designated point is on the Bezier curve.

[0004]

The line determination in the Bezier curve specifying process requires time. This takes time to approximate the straight line of the segment by dividing the Bezier curve, and it also takes time to determine the inside / outside of the rectangular area including each approximated straight line and to calculate the distance. This is because it is necessary to process as many as the number of straight lines that have been formed. This on-line determination processing is performed on all Bezier curves whose specified points are determined to be within the area in the area determination. However, in the conventional intra-region determination process, since the determination as to whether or not the designated point exists is performed on the rectangular region including the Bezier curve, the target of the line determination process often increases.

FIG. 14 is a diagram for explaining a conventional area determination process for determining a Bezier curve to be a target of line determination. FIG. 14 is an example of a case where many figures are overlapped and the inside of each figure is painted while changing the color little by little to express a stereoscopic effect. In such a figure, for example, it is assumed that the designated point 89 (indicated by X in the drawing) is designated at the position shown. In this case, FIG. 14 (b)
As shown in, when the in-region determination is performed on the rectangular regions 90b to 94b including the Bezier curves 90a to 94a, the specified point 89 is included in all the rectangular regions.
Therefore, for all Bezier curves 90a to 94a,
It is necessary to perform the on-line determination processing that requires a long time, and the processing time is longer as a whole. In this way, in the conventional graphic identification processing, the area determination is performed by the rectangular area, so that it is more often determined that it is within the area, and as a result, the target of the line determination processing that takes time also increases. As a result, high speed processing could not be performed.

Therefore, an object of the present invention is to provide an information processing apparatus capable of specifying a graphic at high speed by reducing the number of objects of line determination processing.

[0007]

According to a first aspect of the present invention, as shown in principle in FIG. 1, there are four control points, two anchor points through which a curve passes and two control points that do not pass through. In an information processing apparatus for drawing a curve, an input means 1 for inputting a specified point for specifying a drawn Bezier curve and a predetermined point on a segment of the Bezier curve are calculated, and the predetermined point, the starting point, or one of the control points is calculated. A triangular area composed of points and a triangular area calculating means 2 for calculating a triangular area composed of the predetermined point, the end point and the other control point, and the input means for inputting the two triangular areas calculated by the triangular area calculating means 2. The first judging means 3 for judging whether or not the designated point inputted from 1 is included, and the designated points are included in the two triangular areas by the first judging means 3. With respect to the segment judged to be present, the second judging means 4 for judging whether or not the designated point exists within a predetermined distance, and the second judging means 4 judges that the designated point exists within the predetermined distance. The Bezier curve specifying means 5 for specifying the Bezier curve including the selected segment is provided in the information processing apparatus to achieve the above object.

According to the second aspect of the invention, as shown in principle in FIG. 2, in the information processing apparatus according to the first aspect, a rectangular area calculating means 6 for calculating a rectangular area including four control points of a segment is provided. The triangular area calculating means 2 is provided with a third judging means 7 for judging whether or not the rectangular area calculated by the rectangular area calculating means 6 includes the designated point input from the input means 1. A triangular area is calculated for the segment judged by the third judging means 7 when the rectangular area includes a designated point.

[0009]

In the information processing apparatus according to claim 1, the input means 1
When the designated point is input from, the triangular area calculation means 2 calculates two triangular areas consisting of the designated point and four control points, and first determines whether or not the designated area is included in this triangular area.
Judgment is made by the judging means 3. When the designated point is included in the triangular area, the second determination means 4 determines whether or not the designated point and the segment are within a predetermined distance, and if there is, the Bezier curve identification means 5 includes the Bezier curve including the segment. Specify.

In the information processing apparatus according to the second aspect, the rectangular area including the four control points of the segment is calculated by the rectangular area calculating means 6, and the rectangular area includes the designated point input from the input means 1. When judged by the third judging means 7, the triangular area calculating means 2 calculates a triangular area.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the information processing apparatus of the present invention will be described in detail below with reference to FIGS. Figure 3
Shows the hardware configuration of the information processing apparatus in the first to third embodiments. As shown in FIG. 1, the information processing apparatus includes a CPU (central processing unit) 11 that performs various processing operations such as Bezier curve drawing processing according to this embodiment. The CPU 11 includes a bus line 1 such as a data bus.
3 through ROM15, RAM17, image memory 1
9, an input device 21, a scanner 23, a printer 25, a display 27, and a communication control unit 29 are connected.

The ROM 15 is a read only memory in which various programs for controlling the entire apparatus by the CPU 11 and various data are stored. The ROM 13 stores a graphic processing program such as a Bezier curve specifying processing program according to the present embodiment, a Bezier function, and other various data. The RAM 17 is a random access memory used as a working memory used in various processing operations performed by the CPU 11 and used for storing various data. The RAM 17 stores graphic drawing data for specifying a coordinate value and a graphic type for a straight line and various graphics drawn by graphic processing. Further, the control points automatically set in the Bezier curve drawing processing according to the present embodiment and the input anchor points are also stored in the RAM 17 as Bezier curve drawing data. The programs and data for performing various operations according to this embodiment may be installed in the RAM 17 from another storage medium such as a floppy disk, and the programs and the like may be read from the RAM 17 to operate.

The image memory 19 stores image data, stores graphics drawn by the graphic drawing data stored in the RAM 17, and the data stored in the image memory 19 is stored in the printer 25 or the display. 27
It is designed to be output to. The input device 21 includes various input devices such as a mouse 211 as a pointing device and a keyboard 213. In addition, various input devices such as a tablet and a digitizer (not shown) can be connected to the input device 21. The scanner 23
The input device for reading image data stores the read image data in the image memory 19. The printer 25 and the display 27 are devices that output the graphic data expanded in the image memory 19 according to the graphic drawing data. As the printer 25, various devices such as a dot printer, a laser printer, and an XY plotter are used. Also, as the display 27, CR
Various displays such as T displays and liquid crystal displays are used.

The communication control unit 29 includes a LAN (local area network), a facsimile communication network, and an ISDN.
Personal computers, office computers, etc. via various communication networks such as (service integrated digital network)
It is connected to work stations, electronic publishing systems, word processors and other various information processing devices, and devices of different models. Communication of various data such as graphic drawing data is performed between other information processing devices via the communication control unit 29.

Next, the operation of the embodiment thus constructed will be described. [Principle of Bezier Curve Drawing Process] FIG. 4 shows a drawing state of a curve by a Bezier curve. As shown in FIG. 4, anchor points P0, which constitute four control points,
Of P3 and control points P1 and P2, the starting point P
0, end point P3, two control points P1,
The Bezier curve L0 determined by the direction and distance of P2 will be drawn. This Bezier curve L0 is
It is calculated by the next Bezier function B (t). B (t) = (1- t) 3 · P0 +3 (1-t) 2 · t · P1 +3 (1-t) · t 2 · P2 + t 3 · P3 where a 0 ≦ t ≦ 1.

Next, the operation of identifying the Bezier curve will be described. [Summary of Operation] In the Bezier curve specifying process according to the present embodiment, when the operator inputs the specified point 89 from the mouse 211, the Bezier curve on the specified point 89 is specified.
In the present embodiment, the determination of the input designated point 89 within the area is performed by the anchor points P0 and P that draw the Bezier curve.
3. The in-region determination is performed on two triangular regions including the control points P1 and P2 and the point P4 of the Bezier curve at t = 0.5.

5 to 12 are for explaining the Bezier curve specifying processing operation. As shown in FIG.
It is assumed that the three curves L1, L2, L3 have already been drawn and displayed on the display 27. Then, in the case where the operator inputs the designated point 89 by operating the mouse 211 or the like to specify the curve L2 among these curves,
A specific processing operation of the curve L2 by the information processing device will be described. The CPU 11 monitors whether or not the designated point 89 has been input. As shown in FIG. 12, when the designated point 89 is input (step 1; Y), the parameters n and m are set to 1 respectively. (Step 2). Then, as shown in FIG. 6, each curve L displayed on the display 27 is
Smallest rectangular area Q1, Q2, Q3 containing 1, L2, L3
Is calculated and stored in the RAM 17 (step 3).
Note that each of these rectangular areas may be calculated in advance when drawing a curve, and the data indicating the rectangular area may be stored in the RAM 17 together with the data indicating the figure. In this case, the CPU 11 calculates the smallest rectangular area including each curve from the RAM 17.

Then, the CPU 11 reads out the rectangular area Qn stored in the RAM 17 and sequentially judges whether or not the designated point 89 exists in the rectangular area Qn (step 4).
When the rectangular region Qn includes the designated point 89 (step 4; Y), as shown in FIG. 7, the four control points forming the segment Lnm of the Bezier curve Ln, that is, 2
A minimum rectangular area Rnm including one anchor point (start point and end point) and two control points is calculated (step 5). The CPU 11 determines whether or not the designated point 89 is included in the calculated rectangular area Rnm (step 6). When the designated point 89 is included (step 6; Y),
Point tnm at which the Bezier curve Lnm is divided at t = 0.5
Is calculated (step 7).

FIG. 8 shows a point tnm at which the Bezier curve L0 is divided at t = 0.5. For example, the cubic Bezier curve L0 defined by the four control points P0, P1, P2, and P3 shown in FIG. 8 can be divided into two cubic Bezier curves without changing the shape. That is, the Bezier curve L0 can be divided into a cubic Bezier curve L1 defined by four points P0, P4, P7 and P9 and a cubic Bezier curve L2 defined by four points P9, P8, P6 and P3. Where point t
The control point P9 corresponds to nm. Here, P4 = (P0 + P1) / 2 P5 = (P1 + P2) / 2 P6 = (P2 + P3) / 2 P7 = (P4 + P5) / 2 = (P0 + 2P1 + P2) /
4 P8 = (P5 + P6) / 2 = (P1 + 2P2 + P3) /
4 P9 = (P7 + P8) / 2 = [P0 + 3 (P1 + P2)
+ P3] / 4. As described above, the cubic Bezier curve has a property that it can be subdivided endlessly by repeatedly applying the division recursively.

When the CPU 11 calculates the point tnm, the two triangular areas P0, P1 and tnm are calculated as shown in FIG.
Then, two triangular areas Snm of tnm, P2, and P3 are calculated, and it is determined whether or not the designated point 89 is within the triangular area Snm (step 8). When the designated point 89 is within the triangular area Snm (step 8; Y), the line determination processing is performed for that segment Lnm (segment L22 in FIG. 9) as in the conventional case (step 9). In addition, in the line determination processing in the present embodiment, the segment L
It is approximated by connecting anchor points obtained by dividing nm by 256 with straight lines. The CPU 11 determines whether or not the distance between the approximated straight line and the designated point is within a predetermined tolerance value by the line determination processing, and if it is within the tolerance value (step 1
0), the curve Ln including the segment Lnm is specified, and a predetermined display is performed on the display 27 (step 11), and the specifying process ends.

When the judgments at step 6, step 8 and step 10 are N, the CPU 11 judges whether or not m is the final value (step 12). If m is not the final value (step 12; N), 1 is added to m (step 13), and the processing from step 5 is performed on the next segment L.
nm. Here, when the determination in step 6 is N, it means that the designated point 89 is not included in the rectangular area Rnm, and for example, the rectangular area R11 and the rectangular area R13 shown in FIG. When the determination in step 8 is N, the designated point 89 is included in the rectangular area Rnm, but the designated point 89 is not included in the triangular area Snm. For example, for the rectangular area R12 shown in FIG. The triangular area S12 (see FIG. 11) corresponds to this.

Then, the CPU 11 judges in the steps 12 and 4 that m is the final value (step 12; N) and that the designated point 89 does not exist in the rectangular area Qn (step 4; N). , N are final values or not (step 14). If n is not the final value (step 14; N), add 1 to n (step 1
5), the processing from step 4 is performed on the rectangular area Qn of the next curve Ln. If n is the final value, the designated point 8
The fact that there is no curve corresponding to the position designated by 9 is displayed on the display 27 (step 16), and the specifying process is ended.

FIG. 13 is for explaining the segment Lnm which is the target of the on-line determination processing (step 9) of this embodiment. This FIG. 13 is shown corresponding to FIG. As shown in FIG. 13, in the present embodiment, since it is determined whether or not the designated point 89 is included in the triangular area Snm (step 8), the segment Lnm to be subjected to the line determination processing is 90a only. As described above, in the conventional specific processing, as shown in FIG. 14B, it is necessary to perform the line determination processing that requires a long time for all Bezier curves 90a to 94a. In the example, the number of segments to be subjected to the line determination processing is small, so that the graphic can be specified at high speed.

[0024]

As described above, according to the information processing apparatus of the present invention, the number of lines to be processed is reduced.
The figure can be specified at high speed.

[Brief description of drawings]

FIG. 1 is a principle diagram showing a principle of an information processing apparatus according to the invention of claim 1;

FIG. 2 is a principle diagram showing a principle of an information processing apparatus according to the invention of claim 2;

FIG. 3 illustrates a hardware configuration of an information processing apparatus according to an exemplary embodiment of the present invention.

FIG. 4 is an explanatory diagram of a curve drawing state using a Bezier curve.

FIG. 5 is an explanatory diagram exemplifying a Bezier curve that is a target of a Bezier curve identification processing operation.

FIG. 6 is an explanatory diagram of a minimum rectangular area Qn including each curve in a Bezier curve identification processing operation.

FIG. 7 is an explanatory diagram of a minimum rectangular area Rnm including four control points of a segment in a Bezier curve identification processing operation.

FIG. 8 is an explanatory diagram of a point tnm at which the Bezier curve L0 is divided at t = 0.5 in the Bezier curve identification processing operation.

FIG. 9 is an explanatory diagram of two triangular regions in the Bezier curve identification processing operation.

FIG. 10 is an explanatory diagram of a case where a rectangular region Rnm includes a specified point and a case where the specified point is not included in the Bezier curve specifying processing operation.

FIG. 11 is an explanatory diagram in the Bezier curve identification processing operation when a specified point is not included in the triangular area Snm.

FIG. 12 is a flowchart showing a Bezier curve identification processing operation.

FIG. 13 is an explanatory diagram of a segment Lnm that is a target of the line determination processing according to the embodiment.

FIG. 14 is an explanatory diagram of a conventional area determination process for determining a Bezier curve that is a target for line determination.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input means 2 Triangle area calculation means 3 1st judgment means 4 2nd judgment means 5 Bezier curve specification means 6 Rectangular area calculation means 7 3rd judgment means 11 CPU 13 Bus line 15 ROM 17 RAM 19 Image memory 21 Input device 211 Mouse 213 keyboard 23 scanner 25 printer 27 display 29 communication control unit

Claims (2)

[Claims] 1. An information processing apparatus that draws a Bezier curve from four control points, two anchor points through which a curve passes and two control points that do not pass, a designated point for specifying a drawn Bezier curve. The input means for inputting and a predetermined point on the segment of the Bezier curve are calculated, and the predetermined point, the starting point, a triangular area composed of one control point, and the triangular area composed of the predetermined point, the end point, and the other control point. Triangular area calculating means for calculating, first judging means for judging whether or not the two triangular areas calculated by the triangular area calculating means include the designated point inputted from the input means, and the first judging. Whether the designated point exists within a predetermined distance with respect to the segment determined by the means to include the designated point in the two triangular areas An information processing apparatus, comprising: a second determination means for determining; and a Bezier curve identification means for identifying a Bezier curve including a segment whose designated point is determined to be within a predetermined distance by the second determination means. . 2. A rectangular area calculating means for calculating a rectangular area including four control points of a segment, and whether the rectangular area calculated by the rectangular area calculating means includes a designated point input from the input means. And a third judgment means for judging whether or not the triangular area calculation means calculates a triangular area for the segment judged by the third judgment means to include a designated point in the rectangular area. Claim 1 characterized by
The information processing device described.