JPS5915289A - Display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention is a rask scanning square display device, more specifically, a drawing method for filling the interior of an arbitrary polygon specified by a graph display function according to a given pattern. Related to display devices.

Conventionally, in the graph drawing function of a rask scanning display device, the content of the video refresh memory is read (-1) to determine the boundary line of the polygon based on the logical value of the read data, as a method to fill in a polygon of arbitrary shape. A method of filling in the inside of the designated area is used.However, this method has the following drawbacks.

First, if a figure has already been drawn in the video refresh memory and you want to overlay a figure to fill it, there is a difference between the border of the figure you are currently trying to fill and the figure that has already been drawn. I can't tell. Therefore, in this case, there is a restriction that no figure or character must be drawn in the designated area of the figure to be filled.

2nd K: If the boundary line of the polygon is specified as a line other than a solid line, such as a broken line or a dashed-dotted line, the boundary cannot be detected and therefore cannot be filled.

Third, the fill must be specified to form a closed area. In other words, you cannot fill in the spaces between lines in a line graph.

Fourth, it is necessary to detect valid internal points within the closed region.

In the rask scanning method that plots on grid points, even if one closed area is specified analogously, there is a possibility that an area containing two or more closed areas is specified digitally. In such cases, unpainted areas occur. Therefore, the internal points must be set so that no unpainted areas occur.

An object of the present invention is to solve the above-mentioned drawbacks that occur when filling in a polygon of arbitrary shape on a terminal display device by reading out the contents of the video refresh memory and determining the boundaries (-1). The object of the present invention is to provide a display device that can perform the following without any restrictions.

The display device according to the present invention is a rack scanning type display device having a graph drawing function. This display device uses a work memory that has a number of drawing dots equal to the number of drawing dots assigned to each color of red, green, and blue in the video refresh memory, thereby creating a closed area of a specified figure in the memory. . Furthermore, this device has a means for detecting valid internal points in this closed area, and calculates the next filled line segment by sequentially moving the internal points in the Y-axis direction along the left edge of the boundary line by unit pitch. means for sequentially stacking the points of change between adjacent filled lines from a state where a difference exists to a state where there is no difference as branch internal points; ．． After that, the branch internal point is set as a new internal point.

Embodiments of a display device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a display device equipped with functions for realizing polygon filling of arbitrary shapes. In FIG. 1, a bus 1 includes a central processing unit 2 and an RA
M3 and the graph display control section 4 are connected. A video refresh memory 5 consisting of three areas 51 to 53 such as a red light, a green light, and a green light, and a work memory 8 for work.
is controlled by the central processing unit 2 via the graph display control unit 4. Further, three areas 51 to 53 of the red signal, green signal, and blue signal of the video refresh memory 5 are connected to the video signal control section 6, and the contents of the video refresh memory 5 are converted into video signals suitable for display and sent to the CRT. Display section 7
1C is output. Central processing unit 2 must be specified.

The computer analyzes the command, calculates parameters necessary for graph display, and provides the calculated parameters to the graph display control section 4.

RAM 3 fd Equipped with work areas such as an A stack and a B stack for stacking internal points when the central processing unit 2 performs calculations, and is also used as a buffer for reading/writing the video refresh memory 5. do. The graph display control unit 4 draws graphic patterns such as points, straight lines, circles, and arcs in the refresh memory 5 using a parameter provided by the central processing unit 2. It also reads data stored in the refresh memory 5.

As already explained, the video refresh memory 5 is composed of three areas 51 to 53 for red signal, green signal, and blue signal, respectively, and the contents thereof are displayed on the CR, T display section 7. The work memory 8 is a working memory that has the same functionality as the video refresh memory 5 prepared for filling in, and is used to draw figures in the work area when filling in and to obtain the address of the filled area. It is something. The contents of this work area are not output to the video signal processing unit 6.The second example shows the case of filling in a polygon of arbitrary shape.
It is shown in the figure and its processing order will be explained below.

First, the contents of the work memory 8 are cleared and set to 00.

Second, the red signal, green signal of the video refresh memory 5,
Among the three areas 51 to 53 of the green light, a boundary line is constructed by drawing a straight line with a line type that is divided into an area corresponding to a designated color.

Third, a copy of the boundary line is drawn in the work memory 8 as a solid line. At this time, if a boundary line source closed region is not formed, an auxiliary line is added to form a closed region.

Fourth, in the work memory 8, a valid internal point M (XM, YM) of the closed area surrounded by the boundary line is determined, and the value is saved in the A stack of the RAM 3.

Fifth, read the contents of the work register 8σ) in the negative and positive directions of the X-axis from the internal point M, and find the address where the logical value becomes 1 (XIIYM).

(X2.YM).

Sixth, draw a straight line from (Xi, YM)7)) to (X2°YM) using the specified line type on the specified face of either red, green, or helmet.

Seventh, from (X1+1, YM+1) in the X-axis direction, (
X2-1)'! The point where the logic value is 0 first is defined as the internal point M'. If there is no point whose logical value is O, skip to the 10th step.

Eighth, similarly to the fifth step, the address where the logical value first becomes 1 in each of the negative and positive directions of the X-axis is found from the internal point M', and (Xi').

YM+1), (Xz', YM+1).

Ninth, if X'<Xi, (Xi', YM+
1) In the negative direction of the X-axis, the logical value becomes O at first.
If there is a position where the logical value changes from 1 to 0 between L, (Xt'', YM+1) and Xl in the X-axis stop direction, all those addresses are set as the branch internal point MB of 几AM3. Save to A stack. Then X2'>
In the case of X2, (X2゜YM) in the positive direction of the X axis (
If there is a position where the logical value changes from 1 to 0 between
A.M., q.

Save to the A stack. On the other hand, in the case of X2'<X2, if there is a position where the logical value changes from 1 to 0 between (X2' t YM + 1) and (X2-1) in the All branch internal points MB
, save it to the B stack of RAM3 and jump to the sixth step.

Here, M', Xi', and X2' are M, respectively.
Xi.

Process as X2.

10th, load the branch internal point saved in stack A, stack B, or stack B of RAM 3 as a new internal point M, and jump to the 59th step. In this case, from the A stack If the address is loaded, the seventh
and (YM-4-1) in the eighth step to (Y
M-1). Once all the addresses saved in the A stack and the B stack of RAM 3 have been processed, filling in 9 is completed.

Note that if the inside of the polygon is assumed to be filled and includes independent polygons, (Xt+l) in the seventh step.

If the value of YM) is included in the RAM3Q) A stack or B stack, duplicate filling can be avoided by erasing the value on that stack.

Furthermore, in this example, the left end of the vertices of a polygon has been explained, but in addition to methods of finding from the right end, top end, and bottom end, there are other possible applications in which the figure is arbitrarily rotated. All belong to the scope of the present invention.

Here, an effective method for detecting internal points as described in the fourth step will be explained using an example according to FIGS. 3 and 4.

First, among the specified vertices, find the leftmost point N and the adjacent vertices before and after it as (N-1) and (N+1), and find the midpoint between (N- and (N+1)). P. At this time, since there is at least one internal point of the polygon on the straight line μ connecting point N and point P=z, the contents of the work memory 8 are sequentially read out from point N along the straight line μ, and the first Find the point where the logical value becomes 0 as the internal point M. This pattern is shown in Figure 83. However, as shown in the fourth factor, N and (N-
1) Based on the positional relationship between the straight line connecting N and (N+1), the internal point MIF obtained using the above method
'i points N, S.

It is inside the closed region surrounded by T. Therefore, if Ml is treated as a valid interior point, most of the specified polygon will remain unfilled.

Therefore, check the points above, to the left, to the right of the obtained internal point, and if all the logical values are 1, invalidate that internal point.Continue to check on the straight line β, and check if the logical value is 1. 0
A point above, below, to the left, or to the right of which the logical value is not 1 is defined as a valid internal point. In FIG. 4, Ml is an invalid internal point and M2 is a valid internal point. Write a logical value of 1 to the invalid internal point.

As described above, the present invention provides a method in which filling is performed by reading the contents of the video refresh memory and determining boundaries by providing a work memory that can handle drawing data in addition to the video refresh memory. By removing the above-mentioned drawback and using work memory, even if the overlapping stroke fill is specified in an area where a figure has already been drawn, the work memory will still be able to specify it. A graph can be drawn by finding the address of an area, and when the boundary line is other than a solid line, draw a solid line from r using work memory, and when it does not form a closed area, draw an auxiliary line using work memory. It also has the effect of being able to draw graphs. Furthermore, when finding the interior points of a closed region,
By determining invalid internal points and valid internal points, there is also the effect of eliminating unfilled areas inside a specified polygon.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a display device configured according to the present invention and capable of filling the inside of a polygon of arbitrary shape. FIG. 2 is an explanatory diagram of the operation of filling in a polygon in the display device of FIG. 1. FIGS. 3 and 4 are explanatory diagrams for showing valid points and invalid points inside a polygon of arbitrary shape, respectively. 1... Bus 2... Central processing unit 3... RA
M4...Graph display control section 5...Video refresh memory 6...Video signal control section 7...(, RT display section 8.
...Work memory 51...Red light storage area of video refresh memory 52...Green light storage area of video refresh memory 53...Green light storage area of video refresh memory = 548

Claims (1)

[Claims] In a rask scanning display device having a graph drawing function, there is provided a video refresh memory means for individually storing drawing dots corresponding to each color of red, green, and blue; a working memory means having a number of drawn dots equal to the number of drawn dots drawn;
According to the contents of the video refresh memory means and the work memory means, no pixel exists among the points along the direction from the leftmost vertex of the polygon to the midpoint between both adjacent vertices;
and means for detecting at least one point around the point where no pixel exists, treating it as the first internal point, and sequentially detecting the internal point along the left edge of the boundary line. A method for finding the next filled line segment while moving vertically by a unit pitch, and a method that sequentially considers the points of change between adjacent filled lines from a state where a difference exists to a state where there is no difference as an internal point of a branch. ] A polygon filling drawing method comprising means for stacking at ~, and means for generating the branched interior point as a new interior point after the interior point reaches the top end and reaches the bottom end. A display device comprising: