JPH02140882A - Picking method for graphic display device - Google Patents

Abstract

PURPOSE:To contrive the high speed of a picking processing by deciding the picking processing by means of the arithmetic processing of prescribed numeric data. CONSTITUTION:When a prescribed position on a screen is designated by a pointing device, prescribed small rectangular areas A and B surrounding it are defined, and the coordinate values of graphic element data P stored into a segment buffer are converted into coordinate value data for the nearest side or angle of the external periphery of the rectangular areas, namely the converted coordinate value data. When the graphic element data P are regarded as vectors returning from a prescribed start point to the start point, the locus of the coordinate value data after the conversion can be decided to be the rectangular area in the graphic element when the sum of the vectors for any sides of the rectangular area is not zero, and the designated graphic element data can be specified. Thus, since the graphic element data can be specified by the arithmetic processing of the numeric data, the high speed of the processing can be contrived.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a picking method in a graphic display device, such as a graphic display or work station, which displays graphics.

[Background Art] With the rapid progress of computer-related technology in recent years, the data handled by computers has expanded to include not only data such as numbers and characters, but also data such as figures and images. However, in the case of processing such graphic images, since the amount of data is enormous, there is a problem that the processing time for various processes becomes extremely long, and it is desired to shorten this time.

Here, an example of the configuration of a conventional graphic display device will be described in the eighth section.
This will be explained based on the diagram.

Graphical elements such as straight lines (vectors) and polygons (polygons) represented by X and Y coordinate data are stored in the segment buffer 10 as coordinate value data for each graphical element. The graphic drawing device 12 develops the graphic element data from the segment buffer 10 into pixel data for each pixel on the display screen. This pixel data for each pixel is stored in the frame buffer 16 as screen data in which one pixel on the screen of the display device 14 corresponds to one bit.
will be written to.

Therefore, by reading out the screen data stored in the frame buffer 16 in synchronization with the display timing of the display device, graphics and the like can be displayed on the screen of the display device 14. Note that this display device 14 includes:
For example, a CRT (cathode ray tube) is suitable; in this case,
Reading from the frame buffer 16 is synchronized with the timing of CRT scanning.

In addition, in the graphic display device, contrary to the display procedure described above, a graphic element expressed by multiple coordinate values, such as a polygon, displayed on the screen of the display device 14 is specified using a pointing device such as a mouse or a tablet. , picking processing can be performed to specify which graphic element data in the segment buffer 10 the designated graphic element corresponds to. This picking process is performed by the picking processing device 18, and is performed in the following procedure.

That is, the display device 14 is
If a specific point above is specified, a small rectangular area is defined around this point. Then, the picking processing device 18 sequentially draws the graphic element data in the segment buffer 10 into the work area of the frame buffer 16 for each graphic element.

Then, the graphic element in the segment buffer 10 is specified based on which graphic element data is drawn within the above-mentioned rectangular area.

Problems to be Solved by the Invention: I As described above, in the conventional picking process, graphic element data in the segment buffer 10 is sequentially drawn in the work area of the frame buffer 16. Therefore, the time required to draw in this frame buffer 16 and the time to read the contents and determine whether or not the drawing has been completed are necessary. Therefore, there was a problem that the picking process took a long time.

The present invention has been made with the aim of solving these problems, and provides a graphic display device that realizes faster picking processing by determining picking processing through arithmetic processing of predetermined numerical data. The purpose is to provide a picking method for

[Means for Solving the Problems] As shown in FIG. 8, the picking method in the graphic display device according to the present invention uses a segment buffer that stores graphic element data expressed by a plurality of coordinate values for each graphic element. 10, a graphic drawing device 12 that develops the graphic element data stored in this segment buffer 10 into pixel data for each pixel on the display screen, and displays the pixel data developed by this graphic drawing device 12. A frame buffer 16 that stores screen data corresponding to the screen to be displayed.
, a display device 14 that displays according to the screen data stored in the frame buffer 16, and a pointing device that specifies a predetermined position of the screen data, and a graphic element specified by the pointing device. As shown in FIG. 1, a picking method in a display device specified in a segment buffer 10 includes a step 100 of defining a predetermined small rectangular area surrounding a position specified by a pointing device; and the above-mentioned graphical element. A step 110 of converting the data into converted coordinate value data about the nearest edge or vertex on the outer periphery of this rectangular area, and considering this converted coordinate value data as a vector returning from a predetermined starting point in the graphic element data to that starting point, Step 130 of calculating the sum of the vectors for the sides of
0.

[Operation] When a predetermined position on the screen is specified using a pointing device, a predetermined small rectangular area surrounding the specified position is defined. Then, the coordinate values of the graphic element data stored in the segment buffer are compared with this rectangular area, and the graphic element data is converted to coordinate value data for the side or corner closest to the outer periphery of the rectangular area, that is, converted coordinate value data. do.

When such a conversion is performed, the trajectory of the converted coordinate value data will be different depending on whether the graphic element is outside the rectangular area or the rectangular area is inside the graphic element. In other words, if graphic element data is regarded as a vector returning from a predetermined starting point to that starting point, the locus of the coordinate value data after conversion will be such that if the rectangular area is outside the graphic element, the sum of the vectors for each side is 0. becomes. Therefore, if the vector sum of any side is not 0, it can be determined that there is a rectangular area within the graphic element, and the designated graphic element data can be specified.

In this way, graphical element data can be specified by arithmetic processing of numerical data, so that processing speed can be increased.

[Example] Hereinafter, a picking method in a graphic display device according to the present invention will be described based on the drawings.

Here, since the configuration of the graphic display device used in the present invention is the same as that of the above-mentioned conventional example, the explanation thereof will be omitted here.

Therefore, the specific operation of the picking process will be explained.

As shown in FIG. 2, on the screen of the display device 14,
A polygon P is displayed as a graphic element. This polygon P is (XI, Yl), (X2.

Y2), (X2, Y3), (X4.Y4), (X
This is a polygon specified by six coordinate values: 5, Y5) and (X6, Y6). Let this polygon P represent a set of vectors that sequentially connect each point.

Then, the coordinate a is specified using the light pen 20, which is one of the pointing devices. When this coordinate a is specified, the picking processing device 18 defines a small rectangular area A centered on the coordinate a inside it. Furthermore, when a coordinate is specified by the light pen 20, a small rectangular area B centered on this coordinate is defined inside the rectangular area B.

If the coordinate a is specified, it is determined that the polygon P is outside, and this polygon P is not picked. Further, when the coordinates S are specified, it is determined that the polygon P is inside, and this is checked.

Therefore, this determination will be explained in terms of processing, that is, picking processing.

FIG. 3 shows the processing when the coordinate a is designated by the light pen 20. When the coordinate a is specified by the light pen 20, the X coordinate is
A straight line parallel to the Y axis that is L, XH, and a Y coordinate value of YL,
A small rectangular area A defined by a straight line parallel to the X axis in YH
Define.

Next, each vertex (Xl, Yl
) to (X8.Y6) are converted as shown in FIG. 4 from the relative positions of the rectangular area A and each point.

That is, each vertex (Xi, Yl) of polygon P ~
(X6.Y8) is converted into the coordinate value of the nearest point in the rectangular area A, that is, converted coordinate value data.

Specifically, in Figure 4! For a point in the area, (X, Y) - (XL, YL), for a point in the J area, (X, Y) → (XL, Y), for a point in the C area, (X
, Y)-(XL, YH), for the D region (X,
Y) → (X, Yl(), for E area (X
, Y) → (XH, Yll), for the F region (X,
Y) → (XH, Y), for C area (X, Y
) → (XI, YL), for H region (X, Y) →
Perform the conversion (X, YL).

Therefore, in the example of FIG. 3, the following transformation is performed on the polygon P. In addition, FIG. 5 shows an enlarged view of the main part of FIG. 3.

(Xi, Yl) → (XL, YL), (X2.Y2) → (
XL, YH), (X3, Y3) → (XH.

YH), (X4.Y4)-(XL, Y4), (X5, Y
5) → (XL, YL), (X6.Ye) → (XH, YL
) In this way, the coordinate value (X
i, Yl) to (X8.Ye) are converted coordinate value data (X 11°Y 11), respectively, as shown in FIG.
(X22. Y22), (X33. Y33)
, (X34, Yl4), (X44. Y44
), (X55. Y55), (X8B, Y2O)
is converted to

In this embodiment, the frame vector for the converted coordinate value data corresponding to the outer frame of the rectangular area A converted onto X-XL, that is, (Xll.

Yll) → (X22. Y22), (X34. YB2
) → (X44, Y44), (X44. Y44) → (
X55. Let's focus on Y55). Then, treat this as a directional vector connecting each point, and define the starting point of each vector on X-XL as (XL
.

Ys), and the end point is (XL, Ye), and the sum of Ye-Ys is calculated for these vectors.

In the case of Fig. 5, ΣΔY−(Y22−Yll) +(Y44−YB2)+
Find the value of (Y55-Y44). In the case of this Fig. 5, ΣΔY−
Since the value is 0, the polygon P is determined to be outside the coordinate a (rectangular area A) and is not picked.

Next, a case where coordinates are specified by the light ben 20 will be described. Similarly to the above case, a small rectangular area B defined by XL, Yll, and YLSYl+ is defined with the coordinates S as the center, as shown in FIG. Next, each vertex forming the outer frame of the polygon P is subjected to the transformation shown in FIG. 4, and converted into transformed coordinate value data.

FIG. 7 shows details of the conversion of the converted coordinate value data when this process is performed on the polygon P in FIG. 6.

In this case, the vector on X-XL is the polygon P(7)
The outer frame vector (Xi, Yl) → (X2.Y2) is the frame vector (Xll, Yll) of the converted coordinate value data → (
X22. Y22). Therefore,
Calculating the sum of vectors on X-XL, that is, the value of Ye-Ys, yields ΣΔY-Y22-Yll≠0.

Therefore, the polygon P has a rectangular area B at its internal coordinates, and the polygon P is picked.

In this way, in this embodiment, after performing the conversion process shown in FIG. 4 on the graphic elements, the sum of the values of the converted vectors (end point Ye - start point YS) on X-XL is calculated. , if the value is 0, it is determined to be outside, and if it is not 0, it is determined to be inside. Since such processing can be performed only by calculation of numerical data, the determination processing can be performed without developing the graphic element data in the segment buffer 10 into pixel-by-pixel data and writing it into the frame buffer 16 as in the conventional case. Therefore, picking processing can be performed at high speed.

Note that the direction of the vector when determining the outer frame vector can be arbitrarily determined, and the sides of the rectangular area for determining whether or not the calculation result is 0 can also be arbitrarily determined.

[Effects of the Invention] As explained above, according to the picking method in the graphic display device according to the present invention, graphic element data expressed by a plurality of coordinate values of a polygonal figure, etc., is obtained by simple numerical data calculation. However, it can be determined whether the location is inside or outside the specified coordinates, and picking processing can be performed at high speed. Therefore, the response speed of the pointing device can be significantly improved, and the man-machine interface of the graphic display device can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a flowchart for explaining the operation of a picking method in a graphic display device according to the present invention; FIG. 2 is an explanatory diagram showing the relationship between polygons P developed on a frame buffer and specifications by a pointing device; Figure 3 is an explanatory diagram to explain an execution example of picking processing when no picking is performed, Figure 4 is an explanatory diagram to explain coordinate transformation in picking processing, and Figure 5 is an enlarged view of the main part of Figure 3. An explanatory diagram, FIG. 6 is an explanatory diagram for explaining an example of the execution of the picking process when picking, FIG. 7 is an explanatory diagram that enlarges the main part of FIG. 6, and FIG. 8 is an explanatory diagram of the configuration of the graphic display device. FIG. 2 is a block diagram showing an example. 10... Segment buffer 12... Graphic drawing device 14... CRT 16... Frame buffer 18... Picking processing device

Claims (1)

[Claims] (1) A segment buffer that stores graphic element data expressed by multiple coordinate values for each graphic element, and converts the graphic element data stored in this segment buffer into pixel data for each pixel on the display screen. A graphics drawing device that develops, a frame buffer that stores the pixel data developed by this graphics drawing device as screen data corresponding to a display screen, and a display that displays according to the screen data stored in this frame buffer. A picking method for a display device comprising a device and a pointing device for specifying a predetermined position of screen data, in which a graphic element specified by the pointing device is specified in a segment buffer. Accordingly, a step of defining a predetermined small rectangular area surrounding this rectangular area; a step of converting the graphic element data into converted coordinate value data for the nearest edge or vertex of the outer periphery of this rectangular area; and a step of converting the converted coordinate value data. is regarded as a vector returning from a predetermined starting point in the graphic element data to that starting point, and a step of calculating the sum of the vectors on either side; and a step of identifying the graphic element data if the result of this calculation is not 0, A picking method in a graphic display device, comprising: