JPH02191991A - Multiwindow display system - Google Patents

Abstract

PURPOSE:To obtain a graphic to be finally needed at high speed by adding identification data showing the most preferential order of each window to the data of a prescribed coordinate axis, writing the data to a depth buffer memory and executing the preferential processing of the multiwindow simultaneously with hidden surface or hidden line processing. CONSTITUTION:In order to display the data of the first window, identification data W to show the priority order of the window and coordinate data Z are set to a maximum value and the shape of the window is written to a depth buffer memory 8. A background color is written to a frame buffer memory 9. Then, the data of the first window are displayed. In such a case, the identification data W are still the preferential data of the window and to the coordinate data Z, data Z of the window data are successively set. This operation is repeated until all the processing is finished. As a result, the data of the window, which is covered by the window of the high priority order, of the low priority order are processed samely as the hidden surface processing and the display of the multiwindow to be preferentially controlled is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multi-window display system particularly suitable for three-dimensional graphic display devices.

(Prior Art) Conventionally, as this type of multi-window display system, for example, Japanese Patent Laid-Open No. 63-89144 or Japanese Patent Laid-Open No. 62
The one shown in Japanese Patent No. 275287 is known. FIG. 3 is a block diagram showing the configuration of a conventional graphic display device that performs such multi-window display. Here, an example of a raster scan type three-dimensional graphic display device that performs hidden surface processing using a depth buffer memory is shown. It shows. In the figure, 1 is an interface signal with a computer (not shown), 2 is an interface circuit, 3 is a control device for converting display data, display commands, etc. sent from the computer through this interface circuit 2 into an internal format, 4 is a storage circuit that stores the display data, display commands, etc. that have been converted into an internal format, and the data stored in this storage circuit 4 is sent to the coordinate conversion circuit 5 and the clip processing circuit 6 based on instructions from the control device 3. It is input to the straight line generator 7 through the line generator 7. 8 is a depth buffer memory, 9 is a frame buffer memory, 10 is an interface circuit for a display CRT (cathode ray tube) 11, and 12 is a human-powered device for the control device 3.

Clip processing (“clipping”) by the clip processing circuit 6 is described, for example, in the literature “Graphic Processing Engineering Using Computer Displays” (written by Yamaguchi Fuji University, published by Nikkan Kogyo Shimbun on January 25, 1981), Nos. 138 to 144. As described in the section “Two-dimensional clipping” on page
Since the determination is made based on the upper and lower limit values of the coordinate and Y coordinate, the display is always a rectangular area. Furthermore, in the case of three-dimensional clip processing, the processing is more complicated, but the display is a rectangular area, just as in the two-dimensional case.

FIG. 4 is a block diagram showing the details of the surroundings of the depth buffer memory 8 for executing the hidden surface processing algorithm described above, and reference numerals 1 to 12 indicate the same components as shown in FIG. 3, respectively. It shows. In the figure, 13.14.
15 are respective coordinate data Xc, Yc, Zc generated by the linear generator 7 in the three-dimensional coordinate system of X-Y-Z.
16 is a strobe signal transmission line for sampling each coordinate data Xc, Yc, Zc, 17
is a transmission line for Z coordinate data Z read out from the depth buffer memory 8, and 18 is a comparator for comparing the data value Z, which compares the coordinate data Zc and Z and outputs an output signal to the transmission line 19. do. This output signal becomes a flag signal indicating Zc≦Z, and becomes a write signal for the depth buffer memory 8 and a write signal for the frame buffer memory 9.

Next, the operation will be explained. The straight line generator 7 sequentially generates coordinate data from the start point to the end point based on the start point coordinate data (Xs, Ys, Zs) and the end point coordinate data (XE, YE, Ztt), and applies the hidden surface processing algorithm to the coordinate data. The depth buffer memory 8 is provided for execution. The depth buffer memory 8 reads the coordinate data Z from the memory position determined by the data Xc and Yc among the coordinate data Xc, Yc, and Zc generated by the linear generator 7, and when Zc≦Z, the depth buffer memory 8 reads the coordinate data Z from the memory position determined by the data Xc and Yc. The data is written to the memory location, and coordinate data xc, yc and a flag signal indicating that the mesori contents have been updated are provided to the frame buffer memory 9. In addition, the depth buffer memory 8
If the coordinate data and flag signal are not updated, the coordinate data and flag signal are not manually input to the frame buffer memory 9.

When the frame buffer memory 9 receives the flag signal, it writes preset display data such as brightness or color into the memory location whose address is determined by the coordinate data Xc, Yc. The data written in the frame buffer memory 9 is read out according to the display address generated by the CRT interface circuit 10, and is sequentially read out from the CRT interface circuit 10.
It is sent to I and displayed. Furthermore, data is provided from the input device 12 to the control device 3 as needed.

FIG. 5 is a diagram showing a processing process when multiple windows are superimposed, and FIGS. 5(a) and 5(b) show the process.

(c) shows the display graphic on the CRTII, and the broken line part shows the outline of the window. Further, FIG. 5(b) shows a state in which the windows overlap each other with slight shifts, and the operation will be explained below with reference to these.

The processing order for graphics in each window is such that the windows located at the back are processed first. For this reason, first, the clip processing circuit 6
, the clipping process is executed for window number 1 (Wl), and the linear generator 7 writes the clipping process to the depth buffer memory 8 and frame buffer memory 9, so that the window number is displayed on the CRTII as shown in FIG. 5(a). 1 (Wl) are displayed.

Next, from the clip processing circuit 6 to the linear generator 7,
Point coordinates for filling the entire area of window number 2 (Wl) and a colorless code or a zero brightness code are sent. As a result, the contents of the depth buffer memory 8 and the frame buffer memory 9 are updated, and the window number t (Wl
) is displayed with the portion hidden by the area of window number 2 (Wl) erased. Thereafter, a graphic writing process is performed for window number 2 (W2), and as a result, the entire screen is displayed in a manner that corresponds to how the two windows overlap, as shown in FIG. 5(e).

In this example, the case of two windows has been described, but even if there are more windows as shown in FIG. 5(b), overlapping is performed by repeating the above process.

[Problem to be solved by the invention]

The conventional multi-window display method is as described above, so when multiple windows are overlapped, it is necessary to erase the area of that window before writing figures in the next window. As shown in FIG. 5(d), when each window has a large area and overlaps with a slight shift, there is a problem in that it takes a very long time to update the drawing.

This invention was made in order to solve the above-mentioned problems, and the difference in how windows overlap does not affect the update speed of the figure, making it possible to finally obtain the required figure at high speed. The purpose of this project is to provide a multi-window display method that can display multiple windows.

[Means to solve the problem] The multi-window display method according to the present invention is as follows.

In the multi-window display method of a raster scan graphic display device that is equipped with a depth buffer memory and performs hidden surface processing or hidden line processing, identification data indicating the priority of each window is added to the data of a predetermined coordinate axis. 7 memory, hidden surface processing or hidden line processing, and simultaneous multi-window priority control and display.

[Effect]

In the multi-window display method of the present invention, hidden surface and hidden line processing is performed by comparing the priorities of each window in the depth buffer memory, so that differences in how windows are overlapped do not affect the graphic update speed.

〔Example〕

The multi-window display method according to the present invention adds identification data indicating the priority order of each window to the data of a predetermined coordinate axis and writes it into the depth buffer memory, and performs multi-window priority control at the same time as hidden surface processing or hidden line processing. It was designed so that it can be displayed by going there. That is, by initializing the depth buffer memory with identification data indicating the priority of the window, and writing and comparing the window identification data with the data of the predetermined coordinate axes when displaying the data in the window, This makes it possible to prioritize and display windows of arbitrary shapes.

FIG. 1 is a block diagram showing the configuration of a graphic display device that performs such display control, and the same reference numerals as in the conventional FIG. 4 indicate the same components. That is, this graphic display device is a raster scan type three-dimensional graphic display device that performs hidden surface processing or hidden line processing. In the figure, reference numeral 20 indicates identification data ( 21 is a transmission line for identification data (W) indicating the priority order of windows read out from the depth buffer memory 8.

The above identification data We (W) is added to the Z-axis coordinate data ZC (Z) and stored in the depth buffer memory 8.
FIG. 2 shows the bit positional relationship of these data in the depth buffer memory 8.

Next, the operation will be explained.

The comparator 18 in FIG. 1 compares data Wc+Z in the format shown in FIG. 2 with data W+Z to determine the magnitude relationship. Here, conventionally, the comparator 18 updates the contents of the depth buffer memory 8 when Zc≦2, but in this embodiment, the contents of the depth buffer memory 8 are updated when wc+zc≦W+Z. At this time, the identification data WC is determined to be ascending in order of priority, and Wc=0 is the data with the highest priority. Then, this priority control is performed simultaneously with the hidden surface processing and hidden line processing using the algorithm of the depth buffer memory 8, and the desired updated figure is displayed on the CRTII.

That is, to summarize, the flow of processing is as follows.

(a) First, the depth buffer memory 8 is initialized to the maximum value. At the same time, the frame buffer memory 9 is initialized.

(b) In order to display the data of the first window, the identification data Wc indicating the priority order of the window and the coordinate data ZC are set to maximum values, and the window shape is written into the depth buffer memory 8. Also, the background color of the window is written into the frame buffer memory 9.

(C) Display the data in the first window.

At this time, the identification data Wc remains the priority data of that window, and the coordinate data zc is successively set to the data Z of the window data.

(d) Above (b) until all windows are processed, (
Repeat operation c).

As a result of the above, the data of a window with a lower priority that is covered by a window with a higher priority is removed in the same way as hidden surface processing, and multi-window display with priority control is realized. Therefore, the difference in how the windows overlap does not affect the update speed of the graphic, and it is possible to finally obtain the required graphic at high speed.

In the above embodiment, a three-dimensional display has been described, but a two-dimensional display can also be easily realized assuming that the data Zc is constant.

(Effects of the Invention) As described above, according to the present invention, identification data indicating the priority of each window is added to the data of a predetermined coordinate axis and written into the depth buffer memory, and simultaneously with hidden surface processing or hidden line processing. Because multi-window priority processing is performed, differences in how windows overlap do not affect the update speed of graphics, and the effect is that the final graphics required can be obtained at high speed.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of a graphic display device that performs multi-window display according to the present invention, FIG. 2 is a configuration diagram showing the format of data written to the depth buffer memory 8 of FIG. 1, and FIG. 3 is a conventional diagram. FIG. 4 is a block diagram showing the configuration of a graphic display device that displays cell window
5A, 5B, 5C, and 5D are explanatory diagrams illustrating the conventional process of overlapping multiple windows. It is. 3.---Control device 8---- Depth buffer memory 9---- Frame buffer memory 11------
-CRT 18-... Comparator Note that the same reference numerals in the drawings indicate the same or corresponding parts. Figure 5 (a) (b) (c) (d)

Claims (1)

[Claims] In the multi-window display method of a raster scan graphic display device that is equipped with a depth buffer memory and performs hidden surface processing or hidden line processing, identification data indicating the priority of each window is added to the data of the predetermined coordinate axes to display the depth A multi-window display method characterized by performing multi-window priority control and displaying at the same time as writing to a buffer memory, hidden surface processing or hidden line processing.