JPH10134204A - Graphics display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a graphics display device which performs the Z sorting of drawing commands fast with high precision in a hidden-surface erasing process of the graphics display device. SOLUTION: A Z value range detection part 110 detects the maximum and minimum values of the Z values of drawing commands of one frame to set a Z value range (far surface and near surface), and a group decision number calculation part 120 determines the number of divisions of groups. The division number is optimized on the basis of the number of commands and the Z value range. A sorting process part 130 allots drawing commands in issue order which are read out of a command buffer 220 to corresponding the group according to the Z value and then perform Z sorting in the group. The Z-sorted commands and their addresses are written in a group pointer table 200 and a command pointer table 210 and linked. A graphics processor 300 reads commands by tracing the link order of the table back to perform a drawing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graphics display device, and more particularly to a drawing method for performing Z-sorting of graphic drawing commands with high accuracy and high speed using a small-capacity memory.

[0002]

2. Description of the Related Art In general, computer graphics display processing is performed in the order of traversal, geometry, hidden surface processing, rendering, and display. By performing these series of processes, it is possible to draw and display a three-dimensional or textured image closer to a real object using a triangle, a quadrangle, or a figure having more vertices.

A process called a hidden surface process is a portion for performing a process of not drawing a figure hidden behind another figure when the figure to be drawn is viewed from a viewpoint. The hidden surface processing generally includes a Z-sort method and a Z-buffer method, and uses the depth information of the figure after the geometry calculation. This depth information is generally called a Z value.

The hidden surface processing by the Z-buffer method is performed sequentially for each pixel. That is, the Z value of the pixel of the graphic to be drawn is compared with the Z value stored in the Z buffer, and if the Z value of the graphic stored in the Z buffer is smaller, the Z value is drawn in the frame buffer and the Z buffer. Update the value. As a result of the comparison, if the Z value stored in the Z buffer is larger, the pixel is not drawn and the Z buffer is not updated. By performing such processing, a graphic hidden by the shadow of the graphic using the Z buffer is not drawn, and a more natural display graphic can be obtained.

[0005] Since the Z-buffer method operates on a pixel-by-pixel basis,
In addition, the speed is increased because of hardware processing. However, the system needs to have a Z-buffer of the same size as the display screen on which the Z value is stored, which makes it difficult to apply in fields where low cost is important, such as personal computers, game consoles, and car navigation systems. I have.

In the Z-sort method, before drawing a figure, the drawing order is rearranged using a distance in a three-dimensional space. In general, the graphics are rearranged in order from the furthest graphics to the graphics in the foreground, the drawing order is determined, and the graphics are drawn in accordance with this order.

[0007] As a known example of the Z-sort method, Japanese Patent Laid-Open No. 7-2
No. 96186. In this method, a three-dimensional space is divided into a plurality of blocks according to a distance, and when a drawing command is generated, it is first determined to which block the drawing command belongs. When a block is determined, links are made so that drawing commands are drawn in the order in which they were generated. Then, the block is linked from the block at the back to the block at the front, or from the block at the front to the block at the back, so that the drawing processing is performed. According to this, a memory area for storing graphic data is small, and sorting of graphic data is performed at high speed.

[0008]

The Z-buffer method is fast,
Although the drawing process can be performed with high accuracy, there is a problem that the graphics display device becomes expensive because it is necessary to have a large-capacity buffer.

In the above-described Z-sort method, since only sorting into divided blocks is performed, the intra-block sorting is not performed, so that the accuracy of drawing a figure is poor. Further, the division of the block is fixedly performed in a predetermined Z value range, and a drawing command that cannot be distributed to the block occurs, or an empty block in which the drawing command is not distributed occurs. This results in wasted allocation of memory.

Further, in the conventional Z-sort method, for example, a drawing command is created in order from the back to the front when viewed from the viewpoint in a three-dimensional space, or a drawing command is drawn over many frames such as a background image. Even when the command does not change, since the sorting is always performed, there is a problem that the sorting processing time becomes long.

An object of the present invention is to overcome the above-mentioned problems,
It is an object of the present invention to provide a graphics display device which realizes a low-cost drawing process by a high-precision Z-sort method including an intra-group sort.

It is another object of the present invention to provide an easy-to-use graphics display device which is configured so that the necessity and accuracy of Z-sorting can be selected, and which can flexibly respond to the demands of drawing accuracy and processing speed according to the use of a drawing figure. is there.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to detect a range which can exist in a three-dimensional space from a drawing command in one frame in a three-dimensional graphics display device, and divide this range into a plurality of blocks. This is achieved by distributing a drawing command corresponding to each block and drawing each block in ascending or descending order in the existence range.

The drawing command has a Z value indicating three-dimensional depth information, and the existence range is determined by a maximum value and a minimum value of the Z value of the drawing command in one frame.

The number of divisions of the block is optimized for each frame. This optimization is determined based on the number of drawing commands and / or the existence range.

In the three-dimensional graphics display device, when the three-dimensional depth is divided into a plurality of groups, at least one of the frontmost and the rearmost groups from the viewpoint is added to each of the groups. This is achieved by providing means for dividing the drawing commands so that they are distributed.

In the three-dimensional graphics display device, the issued drawing commands are distributed to a plurality of groups according to the Z value, and sorted within each group according to the Z value. This is achieved by performing drawing processing in ascending order or descending order of the Z value and the Z value in the group.

The Z sort of the drawing command in the group is as follows.
Command Z-sort link table (GPT and CPT)
Is linked to the corresponding group in the table each time a command is issued, and is performed by a link replacement process within the group.

Another object of the present invention is to provide a three-dimensional graphics display device with the necessity of Z-sorting and the accuracy of graphics (whether only distribution to groups or sorting within groups is performed).
Is achieved by providing a means for appropriately selecting

Further, means for selecting a representative point of the Z value is provided for selecting the graphic precision. That is, a point to be referred to at the time of Z sorting of a drawing command such as a triangle or a quadrangle is selected from the first vertex Z value, the center of gravity Z value, or the minimum Z value.

Further, in order to efficiently perform the drawing processing of the graphics processor and the drawing command generation processing for drawing the next frame, a plurality of the drawing command holding units and the drawing pointer holding units, and writing and reading thereof are performed. Is specified alternately or cyclically. Alternatively, a part of the plurality of drawing command holding units holds a drawing command shared by a plurality of frames, such as a background image, and the processing is speeded up by omitting transfer of the drawing command and Z-sorting of the drawing command.

FIG. 2 shows a conceptual diagram of the Z-sort method according to the present invention. Numerals 1 to 5 in the squares in the figure indicate the order in which drawing commands are issued. The order in which the drawing commands are issued is irregular, and in order to display a correct image from the viewpoint, the order from the largest command to the smallest command (in ascending order) with respect to the distance in the three-dimensional space, in particular, the Z value as depth information. ) Must be drawn.

In the case of FIG. 2, the three-dimensional space to be drawn is divided into groups 1 to 3 according to the range of the Z value of the command. This division number is optimized based on the number of commands and the like. Each time a command is issued, it is determined which group the Z value belongs to. The determined command is linked to the corresponding group in the Z-sort link table, and the commands belonging to the group are sequentially compared with the Z value, and the link is reassigned in the order of the command having the largest Z value such as Gr2. In the case of the illustrated example, starting from the command 4, the Z sort is performed so that drawing is performed in the order of 1, 3, 2, and 5 below.

If this operation is performed for all the drawing commands of one frame and the drawing is performed first from the group having a large Z value, a desired image can be displayed. Even within the group, since the processing is as simple as following the link of the Z sort pointer table, high-speed drawing can be performed in the order from the command having the larger Z value to the command having the smaller Z value. if,
If it is important to draw the object in front in the three-dimensional space, replace the link and follow the link.
What is necessary is just to carry out in reverse with respect to a Z value.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A Z-sort system according to an embodiment of the present invention and a graphics display device using the Z-sort system will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram of a graphics display device according to an embodiment of the present invention. The display device includes a processing unit 10 that performs data processing, display processing, input / output processing, and Z-sort processing; a main memory 20 that stores data and drawing commands; and a display unit such as a CRT 40 that performs data reading or writing processing. And an I / O device 50 that performs input / output processing with other processing devices and storage devices.

The processing unit 10 includes a CPU 600 for controlling data processing and other processors, a graphics processor 300 for processing drawing data, a display processor 500 for processing display timing of a display unit, and a CPU.
The system includes a memory controller 400 that arbitrates access to the in-memory 20 such as the graphics processor 300, the graphics processor 300, and the display processor 500, and a Z sort unit 100.

In this embodiment, the CPU 600, the graphics processor 300, the display processor 500,
The memory controller 400 and the Z sort unit 100
Although it is constituted by a chip LSI, it is not limited to this.

The Z sorting section 100 of this embodiment has a Z value range detecting section 110, a group division number calculating section 120, and a sorting section 130. The Z value range detection unit 110
The maximum value Zmax and the minimum value Zmin are obtained from the Z values of all the drawing commands of the frame or one scene, and the existing range (near plane and far plane) of the drawing data is determined without excess or deficiency. The group division number calculation unit 120 determines the optimal division number of the group based on the number of commands and the size of the Z value range, and divides the Z value range into a plurality of groups.
Each time a drawing command is issued, the sort processing unit 130 allocates the drawing command to a corresponding group based on the Z value, and performs Z sorting by link reassignment within the group. The Z sort may be in descending order instead of ascending order of the Z value.

The CPU 600 has the function of the Z sort unit 100 when it is processed by software. Alternatively, it may be built in the graphics processor 300.

The main memory 20 includes a group pointer table (hereinafter abbreviated as GPT) 200, a command pointer table (hereinafter abbreviated as CPT) 210, a command buffer 220 and a frame buffer 230. The command buffer 220 temporarily holds a drawing command processed by the graphics processor 300. The command buffer 2 is stored in the frame buffer 230.
The drawing of the drawing command read from 20 is performed.

The Z sort link table is GPT2
00 and CPT 210, link information indicating the processing order of the drawing commands is written. For example, as shown in FIG. 10, the GPT 200 manages the start and end addresses of drawing commands belonging to each group for each group. The CPT 210 manages, for each command, the address of the drawing command and the link destination address of the Z sort.

Next, the processing procedure of the graphics display device will be described. First, the geometry calculation of the graphic data is performed in the CPU 600. The drawing command on which the geometry operation has been performed is transferred to the Z sort unit 100 under the control of the memory controller 400. In the geometry calculation of the CPU 600, the Z value of the drawing command is calculated based on a representative point such as a triangle or a quadrangle of the command. As will be described later, when the representative point is selected and designated as the minimum Z value or the center of gravity Z value, an arithmetic routine corresponding to each is prepared.

As will be described later, the Z sort unit 100
Rewrite the table contents of T200 and CPT210, Z
The link is re-assigned in order from the command having the larger value to the command having the smaller Z value. When Z-sorting is performed on a drawing command for one scene, the Z-sorting unit 100 sends the graphics command to the graphics processor 3 via the memory controller 400.
A signal for starting drawing is sent to 00.

The graphics processor 300 mainly includes:
Performs arithmetic processing on graphic data of three-dimensional graphics.
That is, the head address of the GPT 200 in the main memory 20 is read and interpreted, and the graphic data as the calculation result is drawn in the frame buffer 230. At this time, GPT2
By sequentially following the link information stored in the 00 or CPT 210, desired graphic data can be drawn.

In tracing the link information, first, the group having the largest Z value is accessed for reading. Drawing processing is performed by referring to commands belonging to the group based on the address of the CPT 210. Next, a command belonging to the immediately preceding group is drawn.

Hereinafter, the configuration and operation of the Z sort unit 100 will be described in detail. FIG. 3 shows a setting example of the near surface (the foreground surface) and the far surface (the innermost surface) in the Z value range. As shown, when the actual depth information is not covered, n
Since the front side of the ear plane and the back side of the far plane are not drawn, the drawing accuracy is reduced. In general, a near plane with respect to depth is fixed at a viewpoint position, and a far plane is fixedly set with a maximum value that can be set by the system, and often covers a wider range than actual depth information.
In this case, if there are many empty data among the plurality of divided groups, the memory area reserved for sorting is wasted.

FIG. 4 shows the configuration of the Z value detecting section according to the present embodiment. The Z value range detection unit 110 includes a maximum Z value detection unit 11.
1 and the minimum Z value detection unit 114. Before performing Z sorting, the Z values of all commands in one frame are checked and the maximum Z value is determined.
Find the value and the minimum Z value. Then, the maximum Z value is far
By setting the Z value of the surface and the minimum Z value as the Z value of the near surface, all of the issued drawing commands are guaranteed.

In the initial state, a small value, for example, 0 is set in the maximum Z value register 112. A large value is set in the minimum Z value register 115. For example, if the data being handled is 16 bits, (2 16 -1) is set. Then, the Z value of the sequentially issued command and the value of the maximum Z value register are compared by the comparators 113 and 116. If the Z value of the command is larger than the value of the maximum Z value register 112, the Z value of the command is changed. Set in the maximum Z register 112. If the Z value of the command is smaller than the value of the minimum Z value register 115,
The value is set in the minimum Z value register 115. This process is 1
For all commands in the frame and set the minimum Z value to n
The Z value of the ear plane and the maximum Z value are defined as the Z value of the far plane.

According to this, at least one drawing command belongs to the foreground and the backmost group, and waste of memory allocation of the GPT 200 is eliminated as compared with the case where the range is fixed. Further, there is an advantage that the resolution is increased. Thereafter, if the Z sort is performed, all the drawing commands can be displayed.

FIG. 5 shows the configuration of the group division number calculator according to the present embodiment. Group division number calculation unit 120 of this example
Has a command number dependent optimization unit 121. The optimization unit 121 includes a command number setting unit 1211 and a mask unit 1
212, a register 1213 for storing the division shift amount and a shift unit 1214. The register 1213 stores information on the number of commands to be distributed to one group, for example, when the number of commands is represented by a power of two, the power is stored. On average 8 (3 in 2) in one group
When the command of (square) is to be distributed, 3 is stored.

When the number of commands is set in the command number setting unit 1211, the mask unit 1212 calculates a power of 2 not exceeding the command number. For example, the number of commands = 7
In the case of 00, an exponent = 512 is output. Shift unit 1
Reference numeral 214 shifts the output value of the mask unit 1212 rightward by the amount of shift of the number of divisions, and outputs the value 1 when the result becomes 0. When the output of the mask unit 1212 is 512 and the shift amount of the number of divisions is 3, the output of the shift unit 1214 is 64, which is the number of group divisions. The average number of commands in one group in this example is 11 (700/64), which is a value close to the desired eight.

The number of commands varies greatly depending on the frame. When the number of commands is small, if the number of divisions is too large, the sorting process will be slowed down, and tables such as GPT will be wasted. In addition, when the number of commands is large, if the number of divisions is too small, the sorting process becomes slow. However, according to the present embodiment, the number of group divisions is optimized according to the number of commands, so that the sorting processing time can be shortened and unnecessary memory allocation is eliminated.

In this embodiment, it is also possible to adopt a fixed division number 123 which is set in advance from the highest priority. The selection in this case is performed by the selector 122. The shift amount of the number of divisions is set to an empirically appropriate numerical value based on the memory capacity of the system, the average number of commands of the frame, and the like.

FIG. 6 shows the configuration of a group division number calculation unit according to another embodiment. Group division number calculation unit 12 of this example
A Z-value dependent optimizing unit 125 is added to 0 'in the configuration of FIG. This is because in the case of optimization depending on the number of commands, depending on the resolution of the Z value, the number of group divisions may be too large and wasted.

In this embodiment, the command number dependent optimizing unit 1
The 21 division number (for example, 64) is input to the exponent calculation unit 1251, and the exponent (= 6) is calculated. On the other hand, the subtractor 1254 outputs a subtraction value (for example, 32) of the maximum Z value 1252 and the minimum Z value 1253. Shift unit 1255
Shifts the subtraction value (= 32) to the right by the power number (= 6) and optimizes the resolution (==
0.5).

Further, a comparator 1257 compares the value with a preset Z value resolution 1256 (for example, 2). If the Z value resolution is larger than 1256, the output value (= 64) of the command number dependent optimizing unit 121 is directly used. Output. In this example, the power is smaller than the Z-value resolution. Therefore, the power-number calculator 1258 calculates the power (= 1) of the Z-value resolution 1256, and the shift unit 1259 calculates the command-number-dependent optimizing unit 1.
The number of divisions from 21 is shifted to the right by an exponent + 1 = 2, and the number of divisions (= 16) optimized with Z-value resolution is output. However, the output value of the shift unit 1259 is rounded up to an integer.

As a result, the number of divisions optimized by the present embodiment eliminates waste of the number of group divisions while guaranteeing that the depth of one group always exceeds the resolution of the Z value.

FIG. 7 shows a schematic processing flow by the Z sort unit of this embodiment. First, the Z-value range from the Z-value range detection unit 110 is used to determine the near plane and far of the figure to be drawn.
A plane (the innermost plane) is set (S1), and the number of group divisions by the group division number calculation unit 120 is fetched (S2).

Next, the processing shifts to the processing by the sort processing unit 130, and the GPT 200 and the CPT 210 are initialized according to the number of divisions (S3). That is, a group ID corresponding to the number of divisions is set in the GPT 200, and "NOP" is set in all the command addresses. At this time, CPT
210 is empty. Next, the issued drawing commands are sequentially input (S4). Then, using the Z value added to the drawing command, it is determined which of the divided groups belongs (S5).

Next, the Z value is compared with a command that already belongs to the group (S6), and link reconnection for connecting in order of the Z value is performed (S7). Finally, it is determined whether the issued drawing command is the last command of one frame by checking whether the number of processing commands has reached the total number of commands (S8). If it is the last drawing command, the Z sort is completed, and the graphics processor 30
Drawing with 0 is started. If not the last, the next drawing command is received, and the above sorting process is repeated.

The in-group determination (S6) and the link replacement process (S7) will be described in detail with reference to FIGS. In this processing, the commands set in the start command section and the end command section of the GPT 200 are
M, ECOM, PCOM is the command for which the Z value was compared immediately before in the group, NCOM is the link destination, and COM is the presently issued self-command. NOP indicates a state in which there is no link to the drawing command (in the initial state) and nothing is executed during drawing.

First, it is determined whether SCOM is NOP in the corresponding group of the GPT 200 (S10). If the determination result is “true”, no drawing command currently belongs to the corresponding group.
The address of the own command COM is set to M and ECOM (S130).

If the judgment result is "false" in the process S10, the Z value of COM is compared with the Z value of SCOM (S2).
0). If the Z value of COM is “true (large)” (S3
0), own command COM has the largest Z value in the corresponding group. Therefore, the address of the SCOM is set to the link destination of the COM (S140), and the address of the COM is set to the SCOM of the GPT 200 (S150).

When the Z value of COM becomes "false (small)" in the process S30, it is determined whether the link destination of SCOM is NOP (S40). This is to determine whether the number of drawing commands in the group is one or more. When the result of the process S40 becomes “true (NOP)”, it means that the number of drawing commands belonging to the group is one. Since the Z value of COM has already been found to be smaller, the order of the links is SC
The order is OM and COM. That is, the address of the COM is set to the link destination of the SCOM (S160), and the GPT 20 is set.
The address of COM is set to ECOM of 0 (S17)
0).

If "false" in step S40, a plurality of commands belong to the group. COM
Has been found to be smaller than SCOM,
The Z value in the group is the second or lower. Therefore,
The link destination of the command PCOM immediately before the Z value comparison in the same group is set to NCOM (S50). This operation can be easily obtained by following the link information. That is, the NCOM can be set by tracing the address of the CTP 210 and the link destination from the address of the SCOM or the ECOM set in the GPT 200 in the order of command setting or in the reverse order.

Next, the Z value of COM and NCOM is compared (S60), and it is determined whether the Z value of COM is large (S7).
0), if the result of the comparison is “true (large)”, the address of COM is set as the link destination of PCOM (S110), and C
Set the NCOM address to the OM link destination (S1
20).

If "false" (small) is obtained in step S70, it is determined whether the link destination of the NCOM is a NOP (S80). If the result is "true (NOP)",
It can be seen that COM has the smallest Z value in the group.
Therefore, the address of COM is set to the link destination of NCOM (S90), and COM is set to ECOM of GPT200.
Is set (S100).

If the result is "false" in step S80, there is a possibility that there is a drawing command having a smaller Z value than the own command COM, so the process returns to step S50, and the Z value is maintained until the link is completed. Is repeated.

FIGS. 10 to 13 show the structure of the GPT and CPT and the transition of the set contents by Z-sort. The sort process is an example of the command shown in FIG. In the initial state, the GPT 200 and the CPT 210 all contain NOP.

When COM1 is first issued, GPT2
In the SCOM and ECOM of the Gr2 of 00, processing S10,
After S130, the address C1 of COM1 is set as shown in FIG. The link destination of COM1 of CPT 210 is NOP.

Next, when COM2 is issued, since the Z value is smaller than COM1 with the same Gr2 as COM1, processing S1 is executed.
0 through S40, S160, and S170, FIG.
(A) and (b) are obtained. The link destination of COM2 is N
OP.

In the case of COM3, the same Gr as COM1 is used.
Since the Z value is smaller than COM1 and larger than COM2 at 2, the link replacement process is performed. That is, S10 to S
Through steps 70, S110, and S120, the link replacement operation is completed, as shown in FIGS. 12 (a) and 12 (b).

Further, COM4 and Gr3 belonging to Gr1
2 are linked, and the drawing commands 1 to 5 located in the three-dimensional space of FIG.
The data is Z-sorted as shown in FIG.

According to the Z sort of this embodiment, the GPT 20
The sorting within the group by 0 and the CPT 210 is performed by replacing the start command to the last command and the respective link destinations with the link indicated by the command address.

Next, another embodiment of the present invention will be described. FIG. 14 shows a configuration of the Z sort unit according to the present embodiment. The configuration other than the Z sort unit is the same as that of the graphics display device of FIG. The representative point selecting unit 14 is included in the Z sorting unit 100 '.
0, a sort selection unit 150, and a sort processing unit 130. The Z value range detection unit 110 and the group division number calculation unit 110 shown in FIG. 1 are not essential, but are better provided.

The representative point selecting section 140 is a means for selectively designating which point of the figure to use the Z value when the issued drawing command is Z-sorted. The drawing accuracy and processing speed can be varied depending on the representative point Z value used.

FIG. 15 is an explanatory diagram of a typical example usable as a representative point of the Z value. (A) is the minimum Z value of the point where the Z value is the minimum, (b) is the Z value of the center of gravity, and (c) is the first vertex Z
Each vector and its drawing figure are shown by values (points first given by a drawing command among a plurality of vertex data).

Regarding the drawing accuracy, the minimum Z value of (a) is the highest, and drawing according to the command is obtained. The center of gravity Z value of (b) obtains the same result in this example, but in general, (a)
Inferior. As for the first vertex coordinates in (c), the drawing accuracy in the depth direction is not guaranteed, as illustrated in FIG. However, the processing time is the opposite,
(C) is the shortest because calculation of the representative point is unnecessary. Then
The order is (b) and (a).

The representative point selection unit 140 of this embodiment uses
A representative point flag holding unit 141 for specifying any of the types is included. The user designates the representative point flag through an application program. This representative point flag is provided to the CPU 600 via the memory controller 400, and is reflected in the Z value calculation in the geometry calculation of the drawing command. As a result, the user can select a desired representative point according to the type and use of the drawing figure, and can appropriately change the priority of the figure accuracy and the processing speed.

On the other hand, the sort selection section 150 includes a group sort selection section 151, a group sort flag storage section 153,
It has an intra-group sort selection section 152 and a group sort flag storage section 154. The selection units 151 and 152 respond to the designation by corresponding flag storage units 153 and 15.
4 is set / reset. Sort processing unit 13
0 includes a non-sorting unit 131, a group sorting unit 132, and an in-group sorting unit 133, and a sort selecting unit 150.
Performs sorting according to the type of the sort flag specified from.

With this configuration, when the processing speed is the highest priority ignoring the display accuracy, the non-sort flag is set, and the drawing commands are issued in the order of issuance via the non-sort unit 161 which is merely a wiring. Write to buffer 220. In this case, since the GPT 200 and the CPT 210 are unnecessary, a memory area for the GPT 200 and the CPT 210 is not secured on the main memory 20.

When the display speed is prioritized over the display accuracy, the group sort flag is set, only the group sort unit 162 is activated, and the drawing commands are distributed to the groups for each Z value. If the display accuracy is given the highest priority, the intra-group sort flag is set, and the group sort unit 1
62 and the in-group sort 163 are activated, and the Z sort shown in FIG. 7 is performed.

According to this embodiment, the processing performance of the system can be realized in accordance with the priority of the drawing accuracy or the drawing speed, so that the optimum use can be made in accordance with the type and purpose of drawing. Further, the memory area in the system can be more effectively utilized.

Next, still another embodiment of the present invention will be described. The graphics display device of the present embodiment is characterized in that the main memory 20 includes a plurality of buffers.

FIG. 16 shows an example of the structure of a graphics display device having a double buffer structure. The GPTBs 240 and CPTs are respectively applied to the GPTA 200, the CPTA 210, and the command buffer A220 as in FIG.
B250 and the command buffer B260 are paired. The control of the double buffer is performed by a buffer selection section 160 provided in the Z sort section 100. In addition,
Other elements provided in the Z sort unit 100 in FIG. 1 are not shown, but are provided better.

The buffer selecting section 160 includes a table buffer selecting section 161 and a table buffer flag holding section 162.
With. Which of the two buffers and tables to use for reading and which to use for writing depends on the CPU.
600 is performed by setting / resetting the table buffer flag holding unit 162 via the table buffer selecting unit 161.

For example, the table buffer flag holding unit 1
If the flag is set to 62, GPTA20
0, CPTA 210, and command buffer A 220 are used for writing, and GPTB 240, CPTB 250, and command buffer B 260 are used for reading. As a result, since reading and writing are performed in parallel, useless waiting time is reduced, and the drawing process of the graphics display device is sped up.

By the way, in surveillance images and the like, an image that fluctuates every moment, such as a person or a vehicle, and an image that hardly fluctuates, such as a background, are often synthesized and drawn. FIG.
FIG. 8A shows this example, in which a fluctuating human A and a building B in the background that do not fluctuate are drawn. In this case, if there is no figure between A and B, the resolution of the GPT 200 at the time of the Z sort is reduced, and the accuracy of the figure data drawn in the frame buffer 230 may be deteriorated. In many cases, the drawing command of a background graphic such as B does not change over a plurality of frames, and Z-sorting on a frame basis increases overhead.

Thus, this drawback is overcome by treating drawing commands that do not change over a plurality of frames separately.
FIG. 17 shows a graphics display device having a triple buffer structure.

The triple structure has a GPTC 27 for handling background images and the like in addition to the double buffer structure shown in FIG.
0, a CPTC 280, and a command buffer C290. In the double buffer structure unit, writing and reading are performed alternately on a frame basis by the table buffer flag 162. On the other hand, for this additional portion, the table buffer selecting unit 161 of the buffer selecting unit 160 Only when the table processing order flag 163 is set from the CPU 600, the link reassignment by the GPT 270 and the CPT 280 and the writing processing of the corresponding frame are performed.

According to this, the drawing process including the Z sort can be speeded up, and still images such as background figures are not subjected to the Z sort every time, so that the drawing accuracy can be maintained and the process can be sped up. FIG. 18B illustrates a screen example of the car navigation according to the present embodiment. The illustrated frame portion and the lower right button are fixed objects, and it is not necessary to issue a command for each frame. Therefore, the processing order flag 163 for these drawing commands is only set first. The background graphic such as a road or a building is updated when the position of the car indicated by the arrow changes by a certain distance or more. At this time, the flag 163 is issued and the background is redrawn.

Therefore, drawing commands and links such as still images and background graphics are stored in the GPTC, CPTC, and command buffer C, updated when the table processing order flag 163 is set, and always operated as a double buffer. , CPTA, command buffer A and GP
If Z-sorting and drawing of a car figure is executed by the TB, CPTB, and command buffer B, and then drawing of the command buffer C is executed, high-speed drawing can be realized with a small command transfer amount.

[0084]

According to the three-dimensional graphics display device of the present invention, when performing Z-sorting, which is one of the hidden surface elimination methods of graphics processing, the number of group divisions is optimized and the drawing command is assigned to each group. By distributing, high-speed and high-accuracy drawing processing becomes possible.

Further, since the Z value range is detected from the command for each frame and group division is performed, all commands can be distributed to the corresponding Z value groups, and useless groups to which commands are not distributed can be reduced.

According to the present invention, Z-sorting within a group is a simple process only by following the link in the Z-sort table. In particular, since the link is changed based on the previous command of the same group or its link destination, the Z sort in the group can be speeded up.

As a result, a high-quality three-dimensional graphics display device can be provided by applying the present invention to personal information terminal devices and the like that require low price and high speed.

According to the present invention, Z used for sorting is
Since the value can be selected from a plurality of representative points, the value can be appropriately selected according to the requirements of display accuracy and processing speed, and the performance and usability of the system can be improved.

Further, according to the present invention, the necessity of sorting and the sort level (whether only group distribution or sorting within a group are included) can be selected. Can be selected appropriately, and the performance and usability of the system can be improved.

Further, according to the present invention, since a plurality of Z sort tables and a command buffer are provided and their writing and reading can be controlled, the drawing processing by the conventional double buffer or triple buffer can be directly performed. Applicable.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a graphics display device of the present invention.

FIG. 2 is an explanatory diagram showing the concept of the Z-sort method of the present invention.

FIG. 3 is an explanatory diagram showing a problem when a near plane and a far plane are fixed.

FIG. 4 is a configuration diagram illustrating an embodiment of a Z value range detection unit.

FIG. 5 is a configuration diagram showing an embodiment of a group division number calculation unit.

FIG. 6 is a configuration diagram showing another embodiment of a group division number calculation unit.

FIG. 7 is a flowchart showing an outline of a Z-sort processing method according to an embodiment of the present invention.

FIG. 8 is a flowchart showing details of the in-group determination and link reassignment processing of the Z-sort processing method of FIG. 7;

FIG. 9 is a flowchart showing a continuation of FIG. 9;

FIG. 10 is an explanatory diagram showing the configuration of GPT and CPT and the initial contents of a table.

FIG. 11 is an explanatory diagram showing transition contents from FIG. 10;

FIG. 12 is an explanatory diagram showing transition contents from FIG. 11;

FIG. 13 is an explanatory diagram showing transition contents from FIG. 12;

FIG. 14 is a configuration diagram showing another embodiment of the Z sort unit.

FIG. 15 is an explanatory diagram of a minimum Z value, a center of gravity Z value, and a first vertex Z value which are representative points of the Z value.

FIG. 16 is a configuration diagram of a main memory having a double buffer structure and a Z sort unit.

FIG. 17 is a configuration diagram of a main memory and a Z sort unit having a triple buffer structure.

FIG. 18 is an explanatory diagram showing a figure to which a triple buffer is applied.

[Explanation of symbols]

10 processing section, 20 main memory, 100 Z sorting section, 110 Z value range detecting section, 111 maximum value detecting section,
114: minimum value detection unit, 120: group division number calculation unit, 121: command number dependence optimization unit, 125: Z value dependence optimization unit, 130: sort processing unit, 131: non-sort unit, 132: group sort unit 133: within-group sort section, 140: representative point selection section, 150: sort selection section, 151: group sort selection section, 152: within-group sort selection section, 160: buffer selection section, 161: table buffer selection section, 162 ... Table buffer flag, 163 ... Table processing order flag, 200 ... GPT
(Group pointer table), 210 ... CPT (command pointer table), 220 ... command buffer,
230: frame buffer, 300: graphics processor, 400: memory controller, 500: display processor.

Continuing from the front page (72) Inventor Ichiro Iimura 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside the Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Norito Watanabe 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture No. Hitachi, Ltd.Hitachi Research Laboratories (72) Inventor Jun Sato 5-2-1, Josuihonmachi, Kodaira-shi, Tokyo Semiconductor Company, Hitachi Ltd.

Claims (9)

[Claims] 1. A three-dimensional graphics display device comprising: a memory for storing a drawing command of graphic data including depth information; a processor for reading and drawing the drawing commands in a predetermined order; and a display unit for displaying a screen. Existence range detecting means for detecting a range that can exist in a three-dimensional space from drawing commands in a frame, block dividing means for dividing the existing range into a plurality of blocks, and sorting for distributing drawing commands corresponding to each block Means for rendering each block in ascending or descending order in the existence range. 2. The method according to claim 1, wherein the existence range detection unit detects a Z value range based on a maximum value and a minimum value of the depth information (hereinafter, referred to as a Z value). And distribute drawing commands corresponding to each block based on the Z value of
A graphics display device, wherein drawing commands in a block are Z-sorted in ascending order or descending order of the Z value range. 3. The graphics display according to claim 1, wherein the block dividing unit optimizes the number of divided blocks based on the number of drawing commands in one frame or the value of the existence range. apparatus. 4. A three-dimensional graphics display device comprising: a memory for storing a drawing command of graphic data including a Z value; a processor for reading and drawing the drawing commands in a predetermined order; and a display unit for displaying a screen. When dividing the value direction into a plurality of blocks, block dividing means for dividing so that at least one drawing command in one frame is distributed to each of the foreground and backmost groups from the viewpoint, A graphics display device provided with sorting means for distributing the rendered drawing command to a group corresponding to the Z value. 5. The method according to claim 1, wherein the sorting unit has a Z sort link table for grouping and sorting the drawing commands, and each time the drawing command is issued. A graphics display device for linking to a corresponding group of the table according to the Z value, and re-linking a plurality of drawing commands existing in the group in ascending or descending order of the Z value. 6. The method according to claim 2, wherein the method of calculating the Z value included in the drawing command is the minimum Z value, the center of gravity Z value, or the first Z value of a polygon represented by the drawing command. A graphics display device comprising Z value representative point selecting means for selecting from any one of vertex Z values. 7. A three-dimensional graphics display comprising: a memory for storing a drawing command of graphic data including a Z value in a plurality of buffers; a processor for reading and drawing the drawing commands in a predetermined order; In the apparatus, a block dividing unit that divides a Z value range included in a drawing command of one frame into a plurality of blocks, distributes the issued drawing command to a group corresponding to the Z value, and increases the Z value in the group. Or a sorter for sorting in descending order and the same number of Z sort link tables as the buffers for storing the drawing order of the sorted drawing commands. 8. The graphics display device according to claim 7, wherein a set of the buffer and the Z-sort link table is configured in a double manner, and writing and reading of each set are performed alternately for each frame. 9. The system according to claim 7, wherein the set of the buffer and the Z-sort link table is formed in triple, and the two sets are alternately written and read for each frame, and the remaining set is written as a background figure. A graphics display device which is performed at the time of updating.