JPH03156686A - Z buffer circuit provided with logarithmic converter - Google Patents

Abstract

PURPOSE:To reduce the capacity of a Z buffer memory installed in a Z buffer memory part by changing logarithmically the weighting of every one bit according to distance between the viewpoint of a driver and an objective body in respect of the viewpoint of the driver and a memory value representing the distance (Z value) to the objective body. CONSTITUTION:A logarithmic conversion part 10 calculates beforehand log.2/ZMAX from the maximum value Zmax of the Z value of objective input, and makes the Z value of the input into a logarithm by using it as a conversion parameter. The Z value added to the logarithmic conversion part 10 is given necessary logarithm converting processing, and the output Z' as this result is added to a comparator 21A in the Z buffer memory part 20A. On the other hand, in a reading register 23A, Z'' in the Z buffer memory 24A is read out in response to a necessary address signal, and it is compared with Z' by the comparator 21A, and when Z'< Z'', Z' is written in a memory position shown by the address signal. Thus, the capacity of the Z buffer memory 20A can be curtailed.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a 115171 circuit with a logarithmic converter, and in particular, a logarithmic converter in which concealment processing in CGI is performed with a small memory capacity. The present invention relates to a Z-buffer circuit with an integrated circuit.

[Conventional technology 1] For example, in order to learn driving techniques for a vehicle such as a passenger car, one does not practice using an actual vehicle from the beginning, but first practices driving in a simulated manner using a so-called simulator device, and then practices driving an actual vehicle. It is practical to practice using
This is also suitable for ensuring the safety of those undergoing training.

By the way, when practicing simulated driving using such a simulator device, the scenery in front of the driver's seat of the simulated vehicle changes every moment to give the trainee a sense of reality while driving the vehicle. It is necessary to have it. Therefore, various types of simulated video display devices have been developed and are currently being used appropriately.

FIG. 2 is a schematic configuration diagram showing a conventional Z buffer circuit as used in the above-mentioned simulated video display device. In this Figure 2, (21) is a comparator, (22) is a write register, (23) is a read register, (2
4) is a Z buffer memory, which constitutes a conventional Z buffer memory section (20).

[Problems to be Solved by the Invention] According to the conventional two-buffer memory unit described above, the memory value representing the distance (Z value) between the driver's viewpoint and the object is 1 regardless of its distance. There is a problem in that the weighting for each bit is constant, which increases the capacity of the Z buffer memory provided in the Z buffer memory section.

This invention was made in order to solve the above-mentioned problems, and the memory value representing the distance (Z value) between the driver's viewpoint and the object is divided into bits according to the distance of the object. An object of the present invention is to obtain a Z-buffer circuit with a logarithmic converter that can logarithmically change weighting and save the capacity of a Z-buffer memory provided in a Z-buffer memory section.

[Means for Solving the Problems] A Z buffer circuit with a logarithmic converter according to the present invention includes: a Z buffer memory section that stores video information corresponding to a Z value as a distance from a driver's viewpoint to an object; and , a logarithmic conversion unit that performs logarithmic conversion calculation processing on the Z value;

[Operation] According to this invention, the distance between the driver's viewpoint and the object (Z
The weighting of each bit is logarithmically changed depending on the distance of the memory value representing the value (value), so that the capacity of the Z-buffer memory provided in the Z-buffer memory section can be reduced. Ru.

[Embodiment 1] Fig. 1 shows a Z with a logarithmic converter which is an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram showing a buffer circuit.

In this Figure 1, (11) is the #1 multiplier, (12)
is an adder, and (13) is a #2 adder, which constitute the logarithmic conversion unit (10) in the embodiment of the present invention. In addition, (21A) is a comparator, (22A) is a write register, (23A) is a read register, (
24A) is a Z buffer memory, which constitutes the Z buffer memory section (20A) in the above embodiment.

According to the logarithmic conversion unit (10) in FIG.
/Zwax) is calculated in advance, and the input Z value is logarithmized using this as a conversion parameter.

Also, the capacity of the above Z buffer memory (24A>) corresponds to the screen (for example, 1024 x 1280),
It has the required depth (for example, 12 bits).

The Z value applied to the logarithmic conversion unit (10) is subjected to necessary logarithmic conversion processing, and the resulting output Z° is applied to the comparator (21A) in the Z buffer memory unit (2OA). On the other hand, in the read register (23A), Z buffer memory <24A
)G, :z'' in the comparator (21A
) to compare with Zo.

Here, when z'<z'', Zo is written to the memory location indicated by the address signal.On the other hand, when Z'≧Z'°, the above writing is not performed.

It should be noted that the Z value used in the embodiments marked with "Y" is a positive number, and there is a property that the smaller the Z value, the higher the accuracy is required. Therefore, by logarithmically converting and retaining this Z value, the Z buffer memory (24A) in the Z buffer memory section (2OA) is
capacity can be reduced.

Now, assuming that the range of Z values mentioned above is 0 to Z IIIAK, the conversion to make this range correspond to 1 to 2 is the formula % Formula % (1) Taking the logarithm of this formula (1), the following formula (2) becomes as follows.

1ogz(1+(Z/Z,,x)) + H+
(2) Next, by performing Taylor expansion on the above equation (2), an approximate equation (3) is obtained.

Iogt (1+ (Z / Z PIAg))ζ(l
og, 2/Z, AX)iZ (Z2/2)l ・・
(3) In the embodiment of the present invention, the logarithmic transformation process of the Z value is performed using the above equation (3).

[Effect of the Invention 1] As explained above, the two-buffer circuit with a logarithmic converter according to the present invention has the following advantages: and a logarithmic conversion unit that performs logarithmic conversion calculation processing on the Z value. , the weighting of each bit is changed logarithmically depending on its distance, and it is possible to save 40% of the Z-buffer memory provided in the Z-buffer memory section. .

[Brief explanation of the drawing]

FIG. 1 shows a Z
Schematic block diagram showing a buffer circuit. FIG. 2 is a schematic block diagram showing a conventional Z buffer circuit. (10) is the logarithmic conversion unit, (11 is the #1 multiplier, (12 is the adder, (13 is the #2 multiplier, (20, (2OA> is the Z buffer memory unit, (21, (
21A) is a comparator, (22122A) is a write register, (23, (23
A) is a read register.

Claims (1)

[Claims] (1) A Z buffer memory unit that stores video information corresponding to the Z value as the distance from the driver's viewpoint to the object; and a logarithmic conversion unit that performs logarithmic conversion calculation processing on the Z value. A Z-buffer circuit with a logarithmic converter.