JP2787510B2 - Graphic display device and display method thereof - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to a graphic display device suitable for enhancing operability for moving, enlarging, and reducing a displayed figure.

[Conventional technology]

In a conventional graphic display device, as shown in FIG.
A graphic processor (hereinafter, referred to as GDP) 12 for performing graphic processing, a memory (hereinafter, referred to as a segment buffer) 16 for storing graphic information, and an I / O controller 17 are connected to each other. The GDP 12 is connected via a graphic bus 13 to a memory (hereinafter referred to as a frame memory) 14 for storing graphic data corresponding to a graphic to be displayed on a display. An I / O mechanism such as a keyboard 18 is connected to the I / O controller 17. In such a system, a clipping process for cutting out a portion protruding from a display area to be displayed is performed as a graphic process corresponding to an interactive operation such as moving, enlarging, and reducing the graphic displayed on the display 15. It is.
The clipping process is performed as follows. In FIG. 9, an area surrounded by straight lines X1, X2, Y1, and Y2 is defined as a display area 1, and four areas of 9 areas including the display area 1 are provided with 4-bit codes. Then, it is checked where the start point and end point of the input line segment are in the nine areas. In the case of the line segment 26, since both the start point and the end point are the code “0000”, they all enter the display area 1. For the line segments 21 and 22, the logical product of the codes at the start point and the end point is calculated, and the result is not "0", so that the line segments 21 and 22 are all outside the display area. Since the start point or the end point of the line segment 23 is “0000”, the display area 1
Intersects. For line segments 24 and 25, display area 1
Since the line may intersect, the line segment is divided into two, and the same processing as in the preceding paragraph is performed for each line segment. When the line segment crosses the display area 1, the following processing is performed. FIG. 10 shows a line segment intersecting with the display area 1. The distance between the start point and the end point of the line segment is bisected to obtain C1, and it is determined whether or not each line segment is in the display area 1. Divide the line segment (starting point-C1) intersecting with the display area 1 into two equal parts, C2
And perform the same processing as in the previous section to obtain an intersection with display area 1.
Find C3 and display the line segment from the starting point to C3. Hereinafter, C4 and C5 are obtained in the same manner, and line segments are displayed. Here, a case in which clipping processing of a circle, an ellipse, an arc, an elliptical arc, and the like is performed will be described with reference to an example of the arc clipping processing shown in FIG. The arc 2 is a figure drawn from the starting point to the end point with a radius r from the origin (center point). When actually drawn, the arc 2 is formed by a set of short line segments. Is performed. Therefore, the processing time of clipping becomes enormous. A conventional method for speeding up the clipping process will be described below. Defines a rectangular area with the smallest area that contains the figure. When moving, enlarging, or reducing a figure,
When the display area 1 is entirely within the display area 1 as shown in the figure, all the graphics in the display area 41 are displayed. Conversely, when the image is not in the display area 1 as in the rectangular area 43, the graphic in the rectangular area 43 is not displayed. However, when a part is included in the display area 1 as in the rectangular area 42, it is necessary to perform the clipping processing for each line segment as described in the preceding paragraph. FIG. 12 shows world coordinates 45.

[Problems to be solved by the invention]

In a conventional graphic display device, operations such as moving, enlarging, and reducing a figure are frequently performed. Therefore, high-speed graphic display is required. On the other hand, only a part of a graphic enters a display area. In many cases, there is a problem that the display speed is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a graphic display device capable of realizing a high display speed even when a part of a graphic is in a display area, and a display method thereof.

[Means for solving the problem]

In order to achieve the above object, a graphic display device according to the present invention defines a rectangular region including a graphic represented by a set of line segments, and maps each line segment of the graphic to a rectangular region intersecting the display region. In a graphic display device having a graphic processor that performs a clipping process and a display that cuts out a graphic by the clipping process and displays the graphic in a display area, at least one quadrangular region including the circular graphic is orthogonally inserted through a center point of the circular graphic. Means for dividing each quadrangular region into four by lines, means for determining whether or not each of the divided quadrangular regions intersects with the display region, Clipping processing is omitted and clipping processing of the other divided rectangular area is omitted. Configured to with that and means to the graphics processor.

Then, in the display of the graphic display method apparatus, a rectangular area containing a figure represented by a set of line segments is defined, and each line segment of the figure is clipped to a rectangular area intersecting the display area, and the figure is cut out. In the display of the graphic display method apparatus for displaying in a display area, at least one quadrangular area including a circular figure is divided into four by dividing each square area by an orthogonal line passing through the center point of the circular figure, and each is divided. Determine whether there is an intersection between the divided rectangular area and the display area,
The clipping process is performed on the divided circular figure of one of the divided quadrangular regions for which the intersection is determined, and the clipping process of the other divided rectangular region is omitted.

[Action]

According to the graphic display device of the present invention, the process of dividing a circular figure (a circle, an ellipse, an arc, and an ellipse arc) symmetrical about the origin (center point) into right, left, up, and down is performed by:
Since it is more easily possible than the data (data of origin coordinates, radius, etc.) required to display the figure and a defined rectangular area is also easily obtained, it does not become a bottleneck in processing time.

〔Example〕

One embodiment of the present invention will be described with reference to FIGS.

As shown in FIGS. 1 to 3, a rectangular area 20 including a figure represented by a set of line segments is defined, and each line segment of the figure 2 is defined with respect to the rectangular area 20 intersecting with the display area 1. Graphic processor 12 for clipping
And a display 15 for displaying, in the display area, a graphic 22 obtained by clipping a portion protruding from the display area 1 by clipping processing, at least one rectangular area including the circular graphic 2.
Means for dividing the quadrangular region 20 into four by orthogonal lines passing through the center point O of the circular figure 2, and determining whether or not each of the divided quadrangular regions 3 to 6 intersects the display region 1. The graphic processor 12 includes means and means for clipping the divided circular figure 22 included in one of the divided quadrangular regions 3 determined to intersect and omitting the clipping processing for the other divided rectangular regions 4 to 6. Configuration.

In the configuration of the apparatus, as shown in FIG. 3, a GDP 12, a segment buffer 16, and an I / O controller 17 are connected via a system bus 11 centering on a CPU 10. GDP
A frame memory 14 is connected to 12 via a graphic bus 13, and a keyboard 18 is connected to the I / O controller 17.
And other I / O mechanisms are connected.

In such a configuration, as shown in FIG.
Taking a circle as an example of a circular figure composed of an ellipse, a circular arc, an elliptical arc, and the like, a quadrangular region (divided quadrangular region) in the first quadrant thereof
3 will be described. In GDP12, the area is recognized by the coordinate value. Therefore, coordinate data is added to the display area 1 and the rectangular area 3. The coordinate data is stored in the segment buffer 16 from the CPU 10 as shown in FIG.
Refers to the data. The coordinate data of the area can be defined by the coordinate points of the lower left vertex (points at which the X and Y values are minimum) and the coordinate values of the upper right vertex (points at which the X and Y values are maximum). In the example of FIG. 4, the coordinate values for recognizing the rectangular area 3 are (Xmin1, Ymin1) and (Xmax1, Ymax1). Similarly, the coordinate values of the display area 1 are represented by (Xmin2, Ymin2) and (Xmax2, Ymax
2) Here, it is checked whether or not the rectangular area 3 is included in the display area 1 at all. In this case, it can be determined whether the following condition is satisfied. When a rectangular area exists at the position of the square 51 as shown in FIG. 6, Xmax1 <Xmin2
Holds. In the case of the square 52, Ymax1 <Ymin2 holds. Similarly, for squares 53 and 54, Xmin1
> Xmax2 and Ymin1> Ymax2. In the case where any one of the four conditions is satisfied, the rectangular area 3 does not enter the display area 1 at all, so that the divided circular figure (1/4 of a circle) in the rectangular area 3 is displayed without performing clipping processing. Not sure. Conversely, when the entire rectangular area 3 is included in the display area 1 (corresponding to the square 55 in FIG. 6), it can be determined whether the following condition is satisfied. Xmin1> Xmax2, Y
When all four conditions of min1> Ymax2, Xmax1 <Xmin2, and Ymax1 <Ymax2 are satisfied, the entire rectangular area 3 is included in the display area 1, so the divided circular figure (1/1 of the circle) in the rectangular area 3
4) displays all without performing clipping processing. In other cases, since the rectangular area 3 intersects the display area 1, clipping processing is performed as before. The above operation is also performed for the divided quadrangular regions 4 to 6 shown in FIG.

As another embodiment of the present invention, a case will be described in which a wire frame in which a shape is expressed only by lines in three-dimensional display is performed. As shown in FIG. 7, figures applicable to three dimensions are limited to circular figures of a rotating body such as a sphere, a cylinder, and a cone. Therefore, in the present embodiment, a cylinder will be described as an example.

In the three-dimensional wire frame display, a minimum unit figure (circle, straight line) forming a cylinder is stored in the segment buffer 16 by the CPU 10. Also, information on the rotation angle is added so that the viewing angle can be freely changed. The GDP 12 reads the rotation angle information from the segment buffer 16. Next, the figure information forming the cylinder is read out one by one, the shape after rotation is calculated based on the rotation angle information read out earlier, the dots are developed in the frame memory 14 and displayed on the monitor 15. In the present embodiment, the processing described in the preceding paragraph is performed on all of the circle 1, the circle 2, the circle 3, the straight line 4 and the straight line 5, and finally, a cylindrical wire frame is displayed on the monitor 15.

Here, when the clipping process is performed as shown in FIG. 8, the straight lines 4 and 5 are omitted from FIG. As can be seen from FIG. 8, since a set of circles or ellipses forming a rotator (in the present embodiment, a cylinder), each circular area such as a circle or an ellipse has Make a decision. In this embodiment, since the divided quadrangular area of the quadrant of the hatched portion in FIG. 8 is not included in the display area 1, the graphic in the hatched portion is not subjected to clipping processing and display.

According to the present invention, a figure (a figure formed by a set of line segments that is symmetrical with respect to the origin and the left and right and up and down, for example, a circle,
When performing clipping processing of an ellipse, an arc, an elliptic arc, and the like, a large unit called a quadrilateral area is divided into quadrants, and when clipping processing is unnecessary, the area can be omitted. Shortening became possible. In a three-dimensional figure, a display method used when drawing a sphere, a rotating body, or the like, and a wire frame model expressing a shape only by a line is a set of circles, ellipses, and the like. .

〔The invention's effect〕

According to the graphic display device of the present invention, the rectangular area is divided into four parts, and each divided rectangular area is determined whether there is an intersection with the display area, and only the circular figure of the intersecting divided rectangular area is clipped. It is possible to increase the display speed including the dimensional figure and shorten the processing time.

[Brief description of the drawings]

FIG. 1 to FIG. 3 are configuration diagrams showing an embodiment of the present invention, and FIG.
FIG. 6 to FIG. 6 illustrate an embodiment, FIG. 7 and FIG. 8 illustrate another embodiment of the present invention, FIG. 9 and FIG. FIG. 12 and FIG. 12 are diagrams for explaining a conventional technique. 1 ... display area, 2 ... circular figure, 3-6 ... divided square area, 20 ... square area, 22 ... divided circular figure.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-117070 (JP, A) JP-A-1-283679 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G06T 15/30

Claims (2)

(57) [Claims] 1. A graphic processor for defining a rectangular area containing a graphic represented by a set of line segments and clipping each line of the graphic to the rectangular area intersecting a display area, and the clipping A graphic display device having a display that cuts out a graphic by processing and displays the graphic in the display area, wherein at least one quadrangular area including the circular graphic is defined by an orthogonal line passing through the center point of the circular graphic. , A means for determining whether or not each of the divided rectangular areas intersects with the display area, and the clipping processing of the divided circular figure of one of the divided rectangular areas for which the intersection is determined. Means for omitting the clipping processing of the other divided quadrangular area and Graphic display apparatus characterized by comprising La Fick processor. 2. A rectangular area including a figure represented by a set of line segments is defined, and each line segment of the figure is clipped with respect to the rectangular area crossing a display area.
In the display method of a graphic display device that cuts out a graphic by the clipping process and displays the graphic in the display area, at least one rectangular area including the circular graphic is defined by an orthogonal line passing through a center point of the circular graphic. It is determined whether or not each of the divided quadrangular regions obtained by dividing the region into four and the display region intersect with each other. A clipping process of the divided quadrangular region of the above is omitted.