JPH07182536A - System and device for plotting - Google Patents

Abstract

PURPOSE:To provide high-speed display performance by parallelly executing plotting for the unit of a command at a display system for receiving plural plotting commands. CONSTITUTION:When the plotting command for new plotting is received, '1' is added to the reception order number of plotting commands stored in a counter 205, this number is stored again, this new reception order number is added to the plotting command and distributed to a processor as depth information to be used for a Z buffer, at the time of plotting execution, the depth information added to the plotting command is compared with the depth information already written in the Z buffer 109 for each dot on the display screen and only when the depth information added to the plotting command is larger, the new depth information is written in the Z buffer 109 and plotted into a display memory 108. Since the Z buffer 109 is used, plotting can be parallelly executed regardless of the limitation of a plotting order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to display on a computer terminal and the like, and more particularly to speeding up display in a client-server type window system.

[0002]

2. Description of the Related Art In a conventional display method in a client-server type window system, when a drawing command is sent from a client side, which is an application program, to a server side, which is a display program, the drawing commands are sequentially displayed in the order in which they are received. It was An example of this is the X window system. For the protocol of server / client communication in the X window system, see "Xlib P
rogramming Manual by Adrian Nye, O'Reilly & Associa
tes, Inc.``X Protocol Reference Manual by Robert
W. Scheifler, O'Reilly & Associates, Inc. ”. One of the characteristics is that the communication path is a message stream that maintains order.

[0003]

In the conventional sequential display method, the drawing commands received from the client are sequentially displayed, so there is a limit to speeding up, which is the first problem. When it is attempted to improve the performance by displaying them in parallel, the second problem is display injustice due to overtaking of the processing of the drawing command.

Fraud due to overtaking will be described using an example. Consider drawing a small blue triangle on top of a large red circle on the display screen. In the sequential display method, when a drawing command for writing a red circle is first sent and then a drawing command for writing a blue triangle is sent, the drawing commands are sequentially displayed, thereby achieving the purpose. On the other hand, in the parallel display method, if you start drawing a small blue triangle while drawing a large red circle, the drawing process will be overtaken in the overlapping area, the small blue triangle will be drawn first, and then the large red circle will be drawn. This is a problem in which small blue triangles do not remain on the display screen.

[0005]

In order to solve the above problems, a Z buffer for drawing order control, means for storing an acceptance sequence number of drawing commands in the Z buffer, and a plurality of accepted drawing commands are provided. Distributes to multiple processors and executes: 1) When a drawing command to be newly drawn is accepted, the stored drawing command acceptance order number is incremented by 1 and stored again, and this new acceptance order number Is added to the drawing command as depth information used in the Z buffer and distributed to the processors. 2) When drawing is executed, the depth information added to the drawing command and the depth information already added to the Z buffer are already written for each dot on the display screen. The depth information added to the drawing command is compared, and new depth information is written to the Z buffer only when the depth information added to the drawing command is larger. For drawing to the display memory, and the configuration of the.

[0006]

With the above structure, the drawing commands executed in parallel have the depth information of a small value added to the drawing command received first and the depth information of a large value added to the drawing command received later. Therefore, even if the drawing command processing is overtaken, the depth information stored in the Z buffer can be compared, and only the command received later can be overwritten. Disappear.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3. In this embodiment, the flow of FIG.
The computer system in FIG. 1 functions as a server by operating each of a plurality of CPUs in the computer. The computer system shown in FIG. 1 includes a computer main body 101 and a display device 102. Multiple CPUs in the computer body 101
(Processor) 104, 105, main memory 106, drawing control device 107, display memory 108, and Z buffer 10
Including 9. The CPUs 104 and 105, the main memory 106, and the drawing control device 107 are connected by a bus 103. On the extension of the bus 103, a client-side device (not shown) is connected via a communication control device. C as an illustration
Although only two of the PU 104 and the CPU 105 are shown, this does not limit the number of CPUs.

FIG. 2 is a diagram in which the data structure of the embodiment is added to the main part of FIG. A reception buffer 201 and a reception order counter 205 are formed in a partial area of the main memory 106. Drawing commands sent from the application program as a client are buffered in the reception buffer 201 like drawing commands 202, 203, and 204. The number of commands actually buffered may change during system operation, and the buffer may become empty. Reception order counter 20
Reference numeral 5 is a counter whose count value is updated when the received drawing command is a drawing execution command. On the other hand, the display storage 108 and the Z buffer 109 are
It has an address corresponding to each pixel of the display screen of the display device 102. In the display memory 108, color information 207 indicating the brightness of each of the red, green, and blue components of the pixel is Z
The buffer 109 stores depth information 206 for referring to whether or not drawing should be performed for the pixel, that is, whether or not the color information 207 at the corresponding address should be updated.

FIG. 3 is a flow chart showing the operation of the embodiment. The operation of the embodiment will be described along the flow of this flowchart. The program of this flowchart operates on a plurality of CPUs such as the CPU 104 and the CPU 105.

First, in step 301, synchronization is confirmed. The request for synchronization is made in step 309, which will be described later. Then, the acceptance buffer 201 is examined (step 3
02), if it is empty, the process is interrupted (step 303). If the reception buffer 201 is not empty, a drawing command is taken out from the reception buffer (step 304), and it is checked whether it is a drawing execution command (step 305). If it is not a drawing execution command, the corresponding other processing is executed (step 306). ), And returns to step 301. If it is a drawing execution command, the value of the reception order counter 205 is incremented by 1 (step 307), and the value of the reception order counter 205 is checked (step 308). If the reception order counter 205 overflows and has returned to 0, the process proceeds to step 309. Otherwise, steps 309 to 311 are skipped and the process proceeds to step 312. In step 309, all processors are synchronized. Then, the drawing control device 107
To clear the Z buffer 109 (step 31
0), and the synchronization is released (step 311). Step 31
Go to 2. The drawing control device 107 sets all the depth information 206 that corresponds to dots in the Z buffer 109 to 0. In step 312, the updated reception order counter 2
The value of 05 is set as "depth information", which is added to the drawing command extracted in step 305, thereby instructing the drawing control device to perform drawing. The drawing control device 107 draws in a pixel unit according to a command. In particular,
For each pixel to be drawn, the depth information 206 in the Z buffer is compared with the depth information in the drawing command, and only when the depth information in the drawing command is larger,
The depth information 206 in the Z buffer is updated with the depth information in the drawing command, and the color information 20 in the display memory 108 is updated.
7 is updated with the drawing color in the drawing command. If the depth information 206 in the Z buffer is greater than the depth information in the drawing command, the color information 207 is not updated for that pixel, and a similar comparison is made for the next pixel indicated by the drawing command. Transfer to processing. When all the drawing targets indicated by the drawing command have been processed in the same way for the pixels, the process returns to step 301.

As described above, the plurality of CPUs 104, 10
Any of the 5 requests sync at step 309,
Except for a special period until the synchronization is released in step 311, the flow of FIG.
Executed in parallel. That is, a plurality of drawing commands are executed in parallel. However, when viewed on a pixel-by-pixel basis, the pixel is overwritten (color information is overwritten) only when the overwriting is performed by a drawing command received later than the drawing command for which the color information currently stored in the display memory 108 is set. Update) is not executed. Therefore, even if the progress of the execution of drawing commands that are executed asynchronously and in parallel with each other is overtaken, the display of the drawing result of the drawing command accepted later is overwritten by the drawing command accepted first and disappears. There is no display fraud.

According to this embodiment, the synchronization is required only when the Z buffer is cleared, and the drawing can be executed in a highly parallel manner.

[0013]

According to the present invention, in a display system that accepts a plurality of drawing commands, by using the mechanism of the Z buffer, it is possible to execute drawing in parallel regardless of restrictions on the drawing order.

[Brief description of drawings]

FIG. 1 is a computer system showing an embodiment of the present invention.

FIG. 2 is a data structure showing an embodiment of the present invention.

FIG. 3 is a flowchart showing an embodiment of the present invention.

[Explanation of symbols]

101 ... Computer main body, 102 ... Display device, 103 ... Bus, 104, 105 ... CPU, 106 ... Main memory, 107
... drawing control device, 108 ... display memory, 109 ... Z buffer.

Claims (4)

[Claims] 1. A drawing method in which drawing is performed using a plurality of drawing commands, and the Z buffer is used for drawing order control of drawing commands by setting the order of acceptance of drawing commands as depth information in the Z buffer. Method. 2. The drawing method according to claim 1, wherein a plurality of received drawing commands are distributed to a plurality of processors and drawing is executed simultaneously. 3. The drawing method according to claim 2, wherein when the depth information of the Z buffer reaches the maximum value, all the processors synchronously clear the Z buffer. 4. A drawing processing apparatus comprising a plurality of processors, each of which receives a drawing command generated by an application program which is a client, and performs drawing processing on the same display screen according to the drawing command received by each of the plurality of processors. A counter that indicates the order in which the drawing commands are accepted by the processor as a whole and a storage unit that indicates the display information and the depth information of the display information corresponding to each pixel of the display screen are provided. Is received as depth information of the received drawing command, and for each pixel of the above-mentioned storage means, when the depth information taken in indicates a later acceptance order as compared with the depth information of the pixel already stored. Update the display information and depth information of the pixel based on the drawing command received only Run the drawing process Te, already drawing processing apparatus characterized by not performing drawing processing for the pixel when the depth information captured than the depth information stored indicates the earlier accepted order.