JP3302455B2 - Information processing device - Google Patents

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 function of drawing a Bezier curve.

[0002]

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

On the other hand, in an information processing apparatus having such various graphic processing functions, it is necessary to perform processing for specifying a predetermined graphic that has already been created. For example, when performing various processes such as deletion, movement, copying, and deformation of an already created graphic, a graphic specifying process described below is performed. First, an 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 the designated point. Recognition is performed by determining whether or not there is a designated point in a predetermined area including a Bezier curve, and if it is included in the area, further determining whether or not there is a designated point on the Bezier curve. Perform on-line determination. Here, the determination on the line is
Repeat the segment (the smallest unit Bezier curve between the input anchor points), approximate with the straight line connecting each anchor point, and check if the specified point is included in the rectangular area including the straight line for each straight line 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 on-line determination in the Bezier curve specifying process requires time. This requires time to approximate a straight line of a segment by dividing a Bezier curve, and also requires time to determine the inside and outside of a rectangular area including each approximated straight line and to calculate a distance. Each of these processes is divided into segments. This is because it is necessary to perform processing for the number of straight lines. This on-line determination processing is performed on all Bezier curves for which the designated point is determined to be within the region in the within-region determination. However, in the conventional in-area determination processing, the determination of whether or not a designated point exists is performed on a rectangular area including a Bezier curve.

FIG. 14 is a diagram for explaining a conventional area determination process for determining a Bezier curve to be subjected to on-line determination. FIG. 14 shows an example of a case in which a large number of figures are overlapped and the inside of each figure is painted while changing the color little by little, thereby expressing a three-dimensional effect. In such a diagram, for example, it is assumed that a designated point 89 (indicated by a cross in the drawing) is designated at the illustrated position. In this case, FIG.
As shown in (5), 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 a long-time on-line determination process, and it takes more processing time as a whole. As described above, in the conventional graphic identification processing, the in-area determination is performed based on the rectangular area, so that the number of cases where the determination is made within the area increases, and as a result, the target of the time-consuming on-line determination processing increases. As a result, high-speed processing could not be performed.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an information processing apparatus capable of specifying a figure at high speed by reducing the number of targets of the on-line determination processing.

[0007]

According to the first aspect of the present invention, as shown in FIG. 1, two anchor points through which a curve passes and two control points through which no curve passes.
In an information processing apparatus that draws a Bezier curve from the four control points of Int , input means 1 for inputting a designated point for specifying the drawn Bezier curve, and a predetermined point on a segment of the Bezier curve are calculated. predetermined point, the start point, one of the co
Control means for calculating a triangular area consisting of control points , the predetermined point, the end point, and a triangular area consisting of the other control point; and inputting the triangular areas calculated by the triangular area calculating means 2 into the two triangular areas. A first determining means 3 for determining whether or not the designated point input from the means 1 is included; and a segment for which the first determining means 3 determines that the two triangular regions include the designated point, Second determining means 4 for determining whether or not the specified point exists within a predetermined distance, and specifying a Bezier curve including the segment for which the specified point is determined to be within the predetermined distance by the second determining means 4 The object is achieved by providing the information processing apparatus with the Bezier curve specifying means 5.

According to a second aspect of the present invention, as shown 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. A third determining means 7 for determining whether or not the rectangular area calculated by the rectangular area calculating means 6 includes the designated point input from the input means 1; and the triangular area calculating means 2 comprises: A triangular area is calculated for the segment determined by the third determining means 7 when the specified point is included in the rectangular area.

[0009]

In the information processing apparatus according to the first aspect, the input means 1
When a designated point is input from the triangular region calculating means 2, the triangular region calculating means 2 calculates two triangular regions each including the designated point and four control points, and determines whether or not the specified point is included in the triangular region.
The judgment is made by the judging means 3. If the specified point is included in the triangular area, the second determining means 4 determines whether or not the specified point and the segment are within a predetermined distance, and if so, the Bezier curve specifying means 5 causes the Bezier curve including the segment to be present. To identify.

In the information processing apparatus according to the present invention, a rectangular area including four control points of a 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 determined by the third determining 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 according to the present invention will be described below in detail with reference to FIGS. FIG.
Represents a 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 the present embodiment. The CPU 11 includes a bus line 1 such as a data bus.
3, a ROM 15, a RAM 17, an image memory 1
9, the input device 21, the scanner 23, the printer 25, the display 27, and the 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 identification processing program according to the present embodiment, a Bezier function, and other various data. The RAM 17 is used as a working memory used in various processing operations performed by the CPU 11, and is a random access memory 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 figures drawn by the figure processing. 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.
It is stored in. The programs and data for performing various operations according to the present 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 and operated.

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

The communication control unit 29 includes a LAN (local area network), a facsimile communication network, an ISDN
(Personal computer, office computer, etc.)
It is connected to a workstation, an electronic publishing system, a word processor, and various other information processing devices, as well as heterogeneous devices. Communication of various data such as graphic drawing data is performed between the other information processing apparatuses via the communication control unit 29.

Next, the operation of the embodiment configured as described above will be described. [Principle of Bezier Curve Drawing Processing] FIG. 4 shows a drawing state of a curve by a Bezier curve. As shown in FIG. 4, the anchor points P0, P3 and the control points P constituting the four control points
Of 1, P2, passes through the starting point P0, the end point P3, 2 two co
A Bezier curve L0 determined by the directions and distances of the control points P1 and P2 is drawn. This Bezier curve L0 is calculated by the following cubic 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 specifying the Bezier curve will be described. [Outline of Operation] In the processing for specifying a Bezier curve according to the present embodiment, when a designated point 89 is input from the mouse 211 by the operator, the Bezier curve on the designated point 89 is specified. In this embodiment, the determination of the input designated point 89 in the area is performed by determining the anchor points P0 and P3 for drawing the Bezier curve and the control point.
Int P1, P2 and t = 0.5 of the Bezier curve
Is determined for two triangular regions consisting of the point P4.

FIGS. 5 to 12 are for explaining the operation for specifying a Bezier curve. As shown in FIG.
It is assumed that three curves L1, L2, L3 have already been drawn and are displayed on the display 27. Then, of these curves, when the operator inputs the designated point 89 by operating the mouse 211 or the like to specify the curve L2,
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 inputted. As shown in FIG. 12, when the designated point 89 is inputted (Step 1; Y), the parameters n and m are set to 1 respectively. (Step 2). Then, as shown in FIG. 6, each of the curves L displayed on the display 27 is displayed.
The smallest rectangular areas Q1, Q2, Q3 including 1, L2, L3
Is calculated and stored in the RAM 17 (step 3).
Each of these rectangular areas may be calculated in advance at the time of drawing a curve, and data indicating the rectangular area may be stored in the RAM 17 together with data indicating the figure. In this case, the CPU 11 calculates a minimum rectangular area including each curve from the RAM 17.

Then, the CPU 11 reads the rectangular area Qn stored in the RAM 17, and sequentially determines whether or not the designated point 89 exists in the rectangular area Qn (step 4).
When the specified point 89 is included in the rectangular area Qn (step 4; Y), as shown in FIG. 7, the four control points constituting the segment Lnm of the Bezier curve Ln, namely, 2
One anchor point (start point, end point) and two control points
The minimum rectangular area Rnm including the rule point is calculated (step 5). The CPU 11 calculates the calculated rectangular area Rn.
It is determined whether or not the specified point 89 is included in m (step 6). When the designated point 89 is included (Step 6; Y),
A 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, a cubic Bezier curve L0 defined by 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
nm corresponds to the control point P9. 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 without limit by repeatedly applying the division recursively.

When the CPU 11 calculates the point tnm, as shown in FIG. 9, the two triangular areas P0, P1, tnm
, Tnm, P2, and P3 are calculated, and it is determined whether or not the designated point 89 exists in the triangular area Snm (step 8). If the designated point 89 is within the triangular area Snm (Step 8; Y), a line determination process is performed on the segment Lnm (segment L22 in FIG. 9) in the same manner as in the related art (Step 9). In the on-line determination process in the present embodiment, the segment L
Approximation is made by connecting the anchor points obtained by dividing nm by 256 using straight lines. CPU11 is the line determination process, the distance between the straight line and the designated point that approximates it is determined whether or not within a predetermined allowable value, if it is within tolerance (Step 1
0; Y) , the curve Ln including the segment Lnm is specified, a predetermined display is displayed on the display 27 (step 11), and the specification processing ends.

If the determination in steps 6, 8 and 10 is N, the CPU 11 determines whether 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 after step 5 is performed on the next segment L
nm. Here, when the determination in step 6 is N, the specified point 89 is not included in the rectangular area Rnm, and corresponds to, for example, the rectangular area R11 or the rectangular area R13 shown in FIG. If the determination in step 8 is N, the specified point 89 is included in the rectangular area Rnm, but the specified point 89 is not included in the triangular area Snm. For example, the rectangular area Rnm shown in FIG. This corresponds to the triangular area S12 (see FIG. 11).

Then, the CPU 11 determines in step 12 and step 4 that m is the final value (step 12; N) and that there is no designated point 89 in the rectangular area Qn (step 4; N). , N is a final value (step 14). If n is not the final value (Step 14; N), 1 is added to n (Step 1).
5) The processing after step 4 is performed on the rectangular area Qn of the next curve Ln. If n is the final value, designated point 8
The fact that there is no curve corresponding to the position specified in 9 is displayed on the display 27 (step 16), and the specific processing is terminated.

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

[0024]

As described above, according to the information processing apparatus of the present invention, the number of objects of the on-line determination processing is reduced.
A figure can be specified at high speed.

[Brief description of the drawings]

FIG. 1 is a principle diagram showing the principle of an information processing apparatus according to the first aspect of the present invention.

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

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

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

FIG. 5 is an explanatory diagram exemplifying a Bezier curve to be subjected to 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 specification processing operation.

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

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

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

FIG. 11 is an explanatory diagram in a case where a designated point is not included in a triangular area Snm in the Bezier curve specifying processing operation.

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

FIG. 13 is an explanatory diagram of a segment Lnm to be subjected to the on-line determination process in the embodiment.

FIG. 14 is an explanatory diagram of a conventional area determination process for determining a Bezier curve to be subjected to on-line determination.

[Explanation of symbols]

 Reference Signs List 1 input means 2 triangular area calculating means 3 first determining means 4 second determining means 5 Bezier curve specifying means 6 rectangular area calculating means 7 third determining 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

Continuation of front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G06T 1/00 G06T 11/00-17/50 G06F 17/50 G06F 3/00 G06F 3/14-3/153

Claims (2)

(57) [Claims] 1. An information processing apparatus for drawing a Bezier curve from four control points , two anchor points through which a curve passes and two control points through which no curve passes, a designated point for specifying the drawn Bezier curve. An input means for inputting, calculating a predetermined point on the segment of the Bezier curve, and calculating the predetermined point, the starting point, a triangular area including one control point , and the predetermined point, the ending point, and the other control;
A triangular area calculating means for calculating a triangular area consisting of points; and a first judging means for judging whether or not the two triangular areas calculated by the triangular area calculating means include the designated point input from the input means. And a second determining means for determining whether or not the specified point exists within a predetermined distance with respect to the segment determined by the first determining means to include the specified point in the two triangular areas; An information processing apparatus comprising: a Bezier curve specifying unit that specifies a Bezier curve that includes a segment for which the specified point is determined to be within a predetermined distance by the second determining unit. 2. A rectangular area calculating means for calculating a rectangular area including four control points of a segment, and whether or not the rectangular area calculated by the rectangular area calculating means includes a designated point input from the input means. And a third determining means for determining whether the triangular area is calculated for the segment determined by the third determining means to include the designated point in the rectangular area. Claim 1.
An information processing apparatus according to claim 1.