JPH0683320A - Sprite control method - Google Patents

Abstract

(57) [Summary] [Purpose] In a computer screen forming method for forming a screen by a method of overlapping two types of screens of a background and a sprite, the sprite is efficiently controlled. [Structure] A field for designating a pattern registered in the sprite generator in the sprite attribute table, a field for designating sprite coordinates, a field for designating up / down and left / right inversion, and a field for designating sprite connection in the X and Y directions. To control sprites.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer screen forming method for forming a screen by a method of superposing two kinds of screens of background and sprite. Specifically, it relates to a sprite control method.

[0002]

2. Description of the Related Art As a method for forming a computer screen,
Generally, there are a bitmap display method and a method of using a dedicated text VRAM which is often used for displaying characters. In addition to these general screen forming methods, as a method often used in games, there is a method of forming a screen by superimposing two kinds of screens of a background, a background representing a main display object, and a sprite.

Generally, when taking a picture or taking a video, considering the object to be photographed and its background, 1
Two objects of the background and the main display are mixed in one picture. Photographs and videos can naturally be expressed by blending the two.

However, when displaying graphics such as games on a computer, all display objects must be managed by a program. Therefore, it is necessary to consider a design that is easy to manage and easy to program. Therefore, such two types of screens of background and sprite are used to manage the screen separately for the background and the main display object. Hereinafter, description will be given based on an example.

The entire background screen is composed of patterns called "characters". Here, a case where the character is 8 × 8 dots as one unit will be described as an example.

FIG. 1 is a diagram showing set values of each register constituting the display screen. The setting value in each horizontal direction is in units of the number of characters, and the vertical direction is in units of the number of rasters.
Consider a case where the entire screen is composed of 32 × 32 characters as shown in FIG. The numbers in the boxes indicate addresses in hexadecimal.

The background attribute table is a table set in the VRAM in order to specify what character and what color is displayed at each character position on the virtual screen. FIG. 3 is a diagram showing the position of the background attribute table in the VRAM and its contents.

A character code representing a character pattern and a CG color code representing a color are designated for each address. As shown in FIG. 4, in this example, the CG color code is designated by 4 bits and the character code is designated by 12 bits of data.

As the character code, a character number defined by a character generator (CG) in the VRAM is designated, and an actual character pattern is registered in the CG in correspondence with this number.

In the character generator (CG), the character pattern is defined as shown in FIG. Since a character composed of 8 × 8 dots on the screen needs to define a 4-bit color code for each dot, four 8 × 8 dot surfaces are used in the character generator. Each surface is called CH0, CH1, CH2, CH3,
One pattern is defined by a total of 16 words of information.

The background display control is performed during the horizontal display period. The data flow for displaying one character will be described with reference to FIGS. As shown in FIG. 6, first, an address is generated from the raster position, the background attribute table is read, and the character code and CG COLOR are obtained.

Next, as shown in FIGS. 7 and 8, the address of the character generator is generated from the character code, the pattern is read, and the result is loaded into the shift register in the video display controller. In this case, the character generator access is 2 for 16-color display.
Word (CH0, CH1 and CH2, CH3) 1 word in 4 color display (CH0, CH1 or CH2, CH
3) Read in.

Then, as shown in FIG. 9, CG COLO
Both R and the captured pattern data are output from the shift register. The video output at this time is shown in FIG.
As shown in. VD7 to VD4 are CG COLOR
However, each bit of CH3 to CH0 appears in VD3 to VD0. 0 is output to VD8 (SPBG).

The display output during the blanking period is VD8 (SPBG) = 1, VD7 to VD0 =, as shown in FIG. 10 (b).
It becomes 0.

The background screen can be smoothly scrolled horizontally and vertically by the video controller. The vertical scroll is the BG shown in FIG.
By controlling the Y scroll register, it can be performed in a raster unit, and horizontal scrolling can be performed in a dot unit by controlling the BGX scroll register.

By drawing the background with such a character, the main display object can be managed as an image different from the background. The background is a display target that represents a surrounding situation that automatically changes according to the movement of the main display object. It is a display object).

The main display object is composed of a pattern in which a predetermined number of dots are used as a unit, and this is called a "sprite".

[0018]

In the method of constructing the two types of screens of the background and the sprite as described above, the sprite display method is left to the individual. For this reason, the content of the program that displays the sprite is not constant, and when multiple people develop one application, it is necessary to negotiate the interface each time. For this reason, it took a long time to develop, and because the programs were not uniform, it was difficult to maintain and manage the software.

There were many problems not only in terms of development and management, but also in terms of display method and memory management. For example, when a vehicle running to the right in the X direction is run in the opposite direction, it is necessary to prepare a pattern of the vehicle in the reverse direction. Also, when drawing a large display object that exceeds the basic unit of sprites, it was the responsibility of each programmer to manage the pattern. This was a very tedious task, making programming more complicated.

The present invention provides a unified sprite display method,
The aim is to develop a table management and usage method to facilitate programming, and to consider effective use of memory in order to make effective use of resources.

[0021]

The present invention is a method of introducing a table for managing sprites, managing sprites based on this table, and achieving an efficient display method and management method. Define the display rules for sprites,
In order to realize that, a sprite attribute table and a sprite generator are set on the RAM.

In the sprite attribute table of the present invention, a field for designating a pattern registered in the sprite generator, a field for designating the coordinates of the sprite, a field for designating up / down / left / right inversion, and a concatenation of sprites in the X and Y directions. Contains a field that specifies

Regarding the sprite management method of the present invention,
The following description is based on one example. FIG. 11 is an example in which (32, 64) of the real screen system is assigned to (0, 0) of the sprite coordinate system. As shown in this figure, each coordinate position can take a value from 0 to 1,023.

Of course, this value may vary depending on the hardware and system, but since it is the coordinate position on the virtual screen (sprite screen), the advantage is that the sprite position can be specified without being aware of the actual screen coordinates. is there. The real screen and the virtual screen need only be associated with each other once before the display, and after that, the system automatically takes the correspondence with the real screen and performs the display. In this example, the sprite has a size of 16 × 16 dots as a unit, and the main display object is represented by a pattern having a size that is an integral multiple thereof.

Each sprite can freely move within the display screen by changing the coordinates, and does not require any redefinition of the pattern. In addition, if the sprites have priorities set and two or more sprites overlap, the sprites can be erased in ascending order.

In order to manage sprites that follow such rules, the sprite attribute table (SA
T) is introduced. The sprite attribute table is a table defined in VRAM similarly to the background attribute table described above, and has a structure as shown in FIG.

The meaning of each component of the sprite attribute table is as follows. As shown in FIG. 13, in the sprite attribute table, the X coordinate,
Y coordinate, pattern number, SPLITE COLOR, Y
There are fields such as bar, CGY, X bar, CGX, SPBG.

As shown in FIG. 14, in this example, 64 sprite attribute tables SP # 0 to SP # 63 can be defined.

The X coordinate and the Y coordinate are fields for specifying the vertical position and horizontal position for displaying the sprite.
By changing the X and Y coordinates, the sprite can be moved to any position on the screen without redefining the sprite pattern.

The pattern number is a number for designating a sprite pattern, and is composed of 11 bits as shown in FIG. 15, and the VRA in which the pattern is stored in the upper 10 bits.
Specify the address of M. This area where patterns are stored is called a sprite generator (SG). Figure 1
6 is an explanatory diagram showing that the sprite pattern is stored in the sprite generator.

The least significant bit of the pattern number field is when the dot width of the sprite is 2 dots and 4 colors,
Used to specify which of (SG0, SG1) or (SG2, SG3) is selected.

In the case of 16-color selection display out of 256 colors, since the pattern defined in the sprite generator includes color information, as shown in FIG. 16, SG0, SG1, SG2,
It consists of four sides of SG3. In the case of four-color display, since two color information is sufficient, either (SG0, SG1) or (SG2, SG3) is selected. In the actual display, sprites are displayed with this superposition. In this way, the sprite attribute table and the sprite generator are associated with each other by the pattern number.

The pattern number in the sprite attribute table is the address of the sprite generator. However, since the address is one word (= 16 bits), the upper 10 bits of the pattern number correspond to the upper 10 bits of the address.

SG0 can be handled by the upper 10 bits.
This is because it is designed so that the lower 6 bits of the address of are set at the position where (000000) ₂ . Note that () ₂ represents a binary number. Data is recorded in the actual sprite generator as shown in FIG.

Since one sprite has four 16 × 16 dot surfaces, each surface SG0, SG1, S
The lower 8 bits of the addresses of G2 and SG3 are (0000
0000) ₂ , (0100 0000) ₂ , (1000
0000) ₂ and (11000000) ₂ .

If the pattern number is (XX XXXXX XXX
X) ₂ is specified, the address of SG0 pointed to by this pattern number is (XXXX XXXXX XX
000000) ₂ and the remaining 3 faces can be calculated automatically. Designation of a 10-bit pattern number is easy to handle and also makes effective use of memory.

SPRATE COLOR is a field for designating an area color code of sprite by 4 bits.

SPBG is a bit that designates the priority of background display and sprite display. "0" performs background display and "1" performs sprite display.

The X bar and the Y bar give instructions to invert the sprite pattern. When the X bar is set to "1", the sprite is displayed by flipping it left and right, and when the Y bar is set to "1", the sprite is displayed upside down. This can reduce the number of patterns to be defined.

FIG. 17 is a display example of a sprite using the X bar and the Y bar. (1) is a pattern registered in the sprite generator, where X bar = 0 and Y bar = 0
Is a sprite that is displayed when is specified.

(2) is a sprite displayed when X bar = 1 and Y bar = 0, and the left and right are inverted. (3)
Indicates that when X bar = 0 and Y bar = 1 are designated, the top and bottom are inverted. In (4), when X bar = 1 and Y bar = 1 are designated, the display is reversed horizontally and vertically.

By providing such inversion designation items in the sprite attribute table, one pattern can be registered in the sprite generator and four patterns can be expressed. Therefore, there is little troublesome pattern registration and the memory is saved.

CGX is a field for specifying joining in the horizontal direction (X direction), and CGG is a field for specifying joining in the vertical direction (Y direction). In this example, CGX has 1 bit, and therefore is either "0" or "1".

FIG. 18 is an example of a sprite attribute table for sprites when CGX = 1.
As shown in FIG. 19, addresses of sprite generators (0000 1000 1000 1000 0000) ₂ to 6
In the 4th word, the first half of the car is the address (0000
1000 1100 0000) The _second half is registered in ₂ to 64 words.

Since the information on the address of the pattern number in the sprite attribute table is the upper 10 bits, the upper 10 bits are (00 0010 001
1) ₂ means that the address (0000 1000 11,000,000) ₂ of the sprite generator is pointed to.

That is, the pattern portion in the rear half of the automobile is pointed. CGY = 0, CG
When X = 0, only one unit of the sprite is displayed on the screen, so only the rear half of the car is displayed.

When CGX is set to "1", the sprite with bit 1 (PC1) of the pattern number of the sprite designated for display as "0" is on the left side, and the sprite with PC1 as "1" is on the right side. Display by connecting the pieces horizontally. That is, according to the values of the X bar and the Y bar, the front half of the automobile is connected to the left and the rear half is connected to the right, and displayed as shown in FIG.

In the conventional method, the upper 10 bits of the pattern number of the SAT must be prepared by the programmer using two SATs, with (0000 1000 10) ₂ on the left and (0000 1000 11) ₂ on the right. did not become. And to make sure the two connect well,
It was necessary to calculate the X coordinate correctly.

By introducing the designation of CGX and X bar to this complexity, a sprite that extends over two can be handled as if it were one sprite, and the complexity of the program is eliminated. As a result, the burden on the programmer is reduced and the program development period can be shortened.

Next, the field CGY will be described. Since CGY has 2 bits, four combinations are possible. However, one is unused. FIG. 21 is a diagram illustrating four combinations of CGY. Bit number 3 (PC3) and bit 2 (PC
By the combination of 2), (0,0), (0,1),
Two or four sprites (1,0) and (1,1) are vertically connected and displayed. That is, sprites are individually displayed when normal is designated, and two are spliced when 2CGY is designated and four are spliced when 4CGY is displayed.

In FIG. 22, 2 in which "11" is designated for CGY
It is an example of a sprite attribute table in the case of CGY. As shown in FIG. 23, the address of the sprite generator (0000 1100 0000 000)
0) ₂ to 64 words is the tip of the pencil, address (0000 1100 1000 0000) ₂ is the top of the pencil axis, address (0000 1101 000)
0 0000) axial bottom of the pencil to _2, address (00
00 1101 1000 0000) ₂ is registered with the rear end of the pencil.

Therefore, when the sprite attribute table is set as shown in FIG. 22, four patterns are connected and displayed as shown in FIG. 24 according to the values of the X bar and the Y bar.

As described above, sprites can be displayed in combination by combining CGX and CGY. This makes it possible to efficiently and easily write a program for connecting and displaying a plurality of sprites.

Since CGX, CGY, X bar, and Y bar can be used in combination, 2 sprites in the horizontal (X) direction,
Combinations of up to 4 sprites in the vertical (Y) direction can be freely expressed in the forward and reverse directions.

The above is an example of the present invention. So two sprites horizontally and four vertically
The two sprites could be joined together at the same time. If needed, more sprites can be joined together. In that case, the above idea can be applied as it is.

That is, it is only necessary to increase the fields of CGX and CGY in the sprite attribute table and prepare a joining routine in the system.

[0057]

The present invention focuses on sprite management by the sprite attribute table and CG. Especially, CGX that connects multiple sprites,
Introduction of CGY and reverse display of sprite direction X
By introducing the bar and the Y bar, the number of patterns to be registered can be reduced, and the image display program that tends to be complicated can be made easy to understand.

The resulting effects are that the program contents are unified, the development time is shortened, and the memory can be effectively used.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a definition of a display screen.

FIG. 2 is an explanatory diagram of addresses in background attributes of characters on a virtual screen.

FIG. 3 is an explanatory diagram showing the positions and contents of background attributes (BAT) in VRAM.

FIG. 4 is an explanatory diagram showing a configuration of a background attribute table.

FIG. 5: Character generator (CG) in VRAM
It is explanatory drawing which shows the position and content.

FIG. 6 is an explanatory diagram of background display control.

FIG. 7 is an explanatory diagram of background display control.

FIG. 8 is an explanatory diagram of background display control.

FIG. 9 is an explanatory diagram of background display control.

FIG. 10 is an explanatory diagram of background video output.

FIG. 11 is an explanatory diagram when (32, 64) in the real screen system is assigned to (0, 0) in the sprite coordinate system.

FIG. 12: Sprite attribute table (SAT) and sprite generator (SG) on VRAM
It is explanatory drawing which shows the state which provided.

FIG. 13 is an explanatory diagram showing the structure of a sprite attribute table.

FIG. 14 is an explanatory diagram showing details of a sprite attribute table on a VRAM.

FIG. 15 is an explanatory diagram of a pattern number field of a sprite attribute table.

FIG. 16 is an explanatory diagram showing details of a sprite generator.

FIG. 17 is an explanatory diagram showing sprite inversion and the like.

FIG. 18 is an explanatory diagram showing a sprite attribute table for connecting sprites in the X direction.

FIG. 19 is an explanatory diagram of an example of an address map of a sprite generator.

FIG. 20 is an explanatory diagram showing a state in which sprites are connected in the X direction.

FIG. 21 is an explanatory diagram of a function of a field CGY.

FIG. 22 is an explanatory diagram showing a sprite attribute table for connecting sprites in the Y direction.

FIG. 23 is an explanatory diagram of an example of an address map of a sprite generator.

FIG. 24 is an explanatory diagram showing a state in which sprites are connected in the Y direction.

Claims (1)

[Claims] 1. A computer screen forming method for forming a screen by superimposing two kinds of screens of a background and a sprite, at least a means for designating a pattern registered in a sprite generator, and a vertical and horizontal inversion of the sprite. A sprite control method comprising: a means for designating and a means for designating connection of sprites in the X direction and the Y direction.