JPH08110951A - Texture mapping device - Google Patents

Abstract

PURPOSE: To allocate texture data in various states and to effectively utilize a memory. CONSTITUTION: The two-dimensional (2D) display data of a three-dimensional (3D) object are stored in a frame memory 4 by a fill coordinate system corresponding to a display screen. Texture data to be mapped on the surface of the 3D object are stored in a texture memory 5 by a texture coordinate system. A texture mappling part 1 inputs fill coordinates and texture coordinates obtained by regulating a range for texture mapping by both the fill coordinate system and texture coordinate system, successively generates fill addresses of respective picture elements in the range regulated by the fill coordinates and generates texture addresses in the texture coordinate system which correspond to the generated fill addresses. And, texture data are read out from a storage location in the memory 5 which is specified by a certain generated texture address and stored in a storage location of the memory 4 which is specified by the fill address.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a texture mapping device for giving an arbitrary texture to the surface of a three-dimensional model displayed on a display device in a three-dimensional graphics system or the like.

[0002]

2. Description of the Related Art In computer graphics,
Texture mapping is known as one of methods for increasing the reality of displaying a three-dimensional object. The texture mapping is a method of realistically displaying the surface of the display object 31 by pasting a surface roughness or a specific pattern 32 on the surface of the three-dimensional display object 31, as shown in FIG. A system that achieves this is equipped with a texture memory for storing texture data to be mapped. Then, based on the vertex coordinates of the polygon to be filled specified by the fill coordinates corresponding to the two-dimensional display plane, a texture having the same shape as the shape defined by the vertex coordinates of the polygon is specified in the texture memory, The texture data within the range is read from the texture memory and allocated within the designated polygon.

[0003]

However, in the above-mentioned conventional texture mapping device, since the texture having the same shape as the shape defined by the vertex coordinates of the designated polygon is defined in the texture memory. For example, when texture mapping is performed on a cube as shown in FIG. 12A, the (A) plane, the (A) plane, and the (C) plane
Although the surface is a square when viewed from the normal direction of each surface, it is necessary to store the texture corresponding to each of the (A) surface, the (A) surface, and the (C) surface. In other words, when focusing on the (A) plane in FIG. 12B, when this cube is rotated in the direction of the arrow by 90 degrees about the x axis, the (A) plane appears like the (A) plane, and Then, when this cube is rotated 90 degrees about the y-axis, it is desired that the (A) plane appears like the (C) plane, but each texture must be stored. In short, in the conventional texture mapping device, even if the same texture is pasted on a certain surface, the surface rotation,
There is a problem that the memory capacity increases because the texture that takes into consideration the movement, the enlargement, and the like must be stored. There is a limit naturally in increasing the memory capacity, and the degree of freedom in the allocation mode is small. If the memory capacity is not increased, only an unnatural texture as shown in FIG. 12C can be mapped.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a texture mapping device capable of allocating texture data in various modes and reducing the memory capacity.

[0005]

A texture mapping device according to the present invention stores frame storage means for storing two-dimensional display data of a three-dimensional object and texture data to be mapped on the surface of the three-dimensional object. The texture storage means for inputting the fill coordinates and the texture coordinates defining the range to be texture-mapped are sequentially generated, and the fill address of each pixel within the range defined by the fill coordinates is sequentially generated. Texture address is generated, texture data is read from the storage location of the texture storage means specified by the generated texture address, and stored in the storage location of the frame storage means specified by the fill address. And a mapping means.

[0006]

According to the present invention, when the range to be texture-mapped is given by both the fill coordinate and the texture coordinate, the mapping means sequentially generates the fill address of each pixel inside the range defined by the fill coordinate. At the same time, a texture address corresponding to the generated fill address is generated, texture data is read from the storage location of the texture storage means specified by the generated texture address, and the frame storage specified by the fill address is stored. Since the data is stored in the memory location of the means, the texture data can be arbitrarily expanded, reduced, rotated, and deformed and allocated depending on how the texture coordinates are given to the fill coordinates. Therefore, various modes of mapping can be performed, and since only the standard pattern needs to be stored in the texture storage unit, the memory capacity can be reduced.

Usually, when displaying a three-dimensional moving image, the polygon once displayed is enlarged, reduced, rotated, etc.
It often stays on the screen for a while. At that time, if the texture mapping device of the present invention is used, the external CPU needs to store only the texture coordinates corresponding to each polygon. Therefore, even if the fill coordinates change due to the change of the moving image. By using the texture coordinates stored as it is, the texture mapping process can be performed according to the change of the moving image. Therefore, natural texture mapping can be performed, and the load on the external CPU can be reduced.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the structure of a texture mapping device according to an embodiment of the present invention. This texture mapping device includes a texture mapping unit 1
And the image memory 2. The texture mapping unit 1 is composed of, for example, one chip, and has an external CP.
It is connected to U3. The image memory 2 is composed of a frame memory 4 and a texture memory 5, and the frame memory 4 stores three-dimensional image data to be texture-mapped in a fill coordinate system corresponding to a display plane. Stores the texture data to be mapped in the texture coordinate system.

From the CPU 3, the three vertex coordinates (fill coordinates) of the triangle to be mapped in the fill coordinate system.
And the three vertex coordinates (texture coordinates) of the triangle to be pasted in the texture coordinate system corresponding to each vertex. These coordinates are C according to the user's intention.
It is set by PU3. Note that the user may specify only the initial coordinates, and thereafter, the CPU 3 may calculate the fill coordinates only by giving control data such as rotation, movement, enlargement, and reduction. What is important here is that the initial coordinates of the fill coordinates and the texture coordinates are set to the CPU3
After being given to the texture mapping unit 1, the fill coordinates are updated with the rotation, movement, enlargement, and reduction of the object, but the stored initial coordinate values can be used for the texture coordinates as they are. This significantly reduces the burden on the user or the CPU 3.

These coordinate data are supplied to the fill address generator 12 and the texture address generator 13 via the CPU interface 11. As used herein, the term "address" does not necessarily indicate a memory address, but is synonymous with x, y coordinate values. In a general memory, memory address cells arranged two-dimensionally are designated by row / column addresses, so that the memory address and the x, y coordinates correspond one to one. Therefore, "memory address" is also "x,
There is no big difference in the "y coordinate value". The fill address generation unit 12 determines, from the given fill coordinates, the frame memory 4 for all pixels in the triangle defined by the fill coordinates.
The above fill addresses are sequentially generated along the horizontal scanning direction. The texture address generation unit 13 generates a texture address on the texture memory 5 corresponding to the fill address generated by the fill address generation unit 12. The texture address generated by the texture address generation unit 13 is supplied to the gate circuit 14. Gate circuit 1
Reference numeral 4 limits the given texture address to an address within a predetermined storage area of the texture memory 5 and converts it into a texture address of a designated pattern. The output of the gate circuit 14 is supplied to one input terminal of the selector 15. The fill address from the fill address generation unit 12 is supplied to the other input end of the selector 15. The selector 15 switches between the two addresses under the control of the control unit 16 and supplies it to the image memory 2 as a read address or a write address. The data processing unit 17 performs predetermined processing on the data read from the image memory 2 as needed. The control of each of these units is executed by the control unit 16.

Next, the operation of the texture mapping device configured as described above will be described. FIG. 2 is a flowchart showing a processing procedure when the texture mapping processing is executed by this apparatus. When the fill coordinates A, B, C and the texture coordinates TA, TP, TC are input from the CPU 3, the fill address generation unit 12 of the texture mapping unit 1 first sets the fill coordinates A, B, C in ascending order of y coordinates. After sorting, the texture coordinates TA, TB, and TC are rearranged correspondingly. Then, the names are changed again from A, B, and C in the ascending order of the y-coordinates, and TA, TB, and TC are also changed correspondingly (S1). The relationship between the sorted points is as shown in FIGS. 3 (a) and 3 (b), for example. The coordinate values of these points are stored in the following variables xa, ya, xb, yb, ... (S2).

[0012]

Xa = x coordinate of A point ya = y coordinate of A point xb = x coordinate of B point yb = y coordinate of B point xc = x coordinate of C point yc = y coordinate of C point txa = TA point X-coordinate of tya = y-coordinate of TA point txb = x-coordinate of TB point tyb = y-coordinate of TB point txc = x-coordinate of TC point tyc = y-coordinate of TC point

Subsequently, ya is stored as the initial value of y (S3), and the x coordinate xd of the point D and the x coordinate of the point E are calculated by the following equation 2.
Coordinate xe, x, y coordinates txd, tyd of TD point, and T
The x and y coordinates txe and tie of point E are obtained (S
4).

[0014]

## EQU00002 ## xd = xa + (xb-xa) * (y-ya) /
(Yb-ya) xe = xa + (xc-xa) * (y-ya) / (yc-
ya) txd = txa + (txb-txa) * (y-ya) /
(Yb-ya) txe = txa + (txc-txa) * (y-ya) /
(Yc-ya) tyd = tya + (tyb-tya) * (y-ya) /
(Yb-ya) type = tya + (tyc-tya) * (y-ya) /
(Yc-ya)

Next, xd is stored as the initial value of x (S
5), x, y, xd,
Transfer xe, txd, txe, tyd, and tie. The texture address generation unit 13 calculates the
The x, y coordinates tx, ty of the point are calculated (S6).

[0016]

## EQU00003 ## tx = txd + (txe-txd) * (xx
d) / (xe-xd) ty = tyd + (tye-tyd) * (x-xd) /
(Xe-xd)

Then, the output of the texture address generator 13 is selected by the selector 15 to read the texture data at the address (tx, ty) of the TP point in the texture memory 5 (S7), and then the selector 1
By selecting the output of the fill address generation unit 13 by 5, the data is stored in the address (x, y) of the point P of the frame memory 4 (S8). At this time, the data processing unit 17 may perform shading processing or the like on the stored data before storing the data.

The above processing is repeatedly executed while incrementing x by 1 until x reaches xe (S9,
(S10), when x reaches xe, y is incremented by 1 (S1
2) The next D point and E point are obtained, and the x and y coordinates of the P point and the TP point are calculated by the same operation. In this operation, y is yc
It continues until it reaches (S11). When y reaches yb, the following formula 4 is used instead of the formula 2 for the calculation formulas of xd, txd, and tyd in step S4.

[0019]

Xd = xb + (xc-xb) * (y-yb) /
(Yc-yb) txd = txb + (txc-txb) * (y-yb) /
(Yc-yb) tyd = tyb + (tyc-tyb) * (y-yb) /
(Yc-yb)

By this operation, the texture data stored in the texture memory 5 is mapped to the area designated by the fill coordinates.

Now, assuming that the texture data as shown in FIG. 4 is stored in the texture memory 5, the coordinates of the vertices A, B and C of the slightly flattened triangle as shown in FIG. 3A as fill coordinates. When TA, TB, and TC of FIG. 4 are specified as the texture coordinates, the texture mapped to the triangle specified by the fill coordinates is deformed slightly flat as shown in FIG. 5A. It becomes an image. Similarly, if TA ′, TB ′, and TC ′ of FIG. 4 which are slightly rotated with respect to the previous example are designated as the texture coordinates, the texture becomes as shown in FIG. 5B.
The image will be slightly rotated. If TA ", TB", and TC "of Fig. 4 smaller than the previous example are designated as the texture coordinates, the texture becomes an enlarged image as shown in Fig. 5C. According to this apparatus, the texture to be mapped can be freely transformed, rotated, enlarged, or reduced by setting the texture coordinate to an arbitrary value with respect to the fill coordinate.

According to this device, for example, FIG.
As shown in FIGS. 7A, 7B and 7C, the texture data shown in FIG. 7A is made to correspond to the six squares forming each surface of the cube as shown in FIG. When rotated, the coordinates of each vertex of the cube are calculated and input by the CPU 3, but the texture coordinate may be the value initially set regardless of how the cube is rotated.
Therefore, the calculation load of the CPU 3 can be reduced.

By the way, when the texture data is composed of repetitive patterns as in the above example, it is not economical to store the texture data corresponding to the entire fill coordinate system in the texture memory 5. Therefore, in this apparatus, as shown in FIG. 8, only a part of the texture data is stored, and various texture data are also stored so that the texture memory 5 can be effectively used. In the illustrated example, the relationship between each texture address range and texture data is as shown in Table 1 below.

[0024]

[Table 1]

Therefore, the upper 4 bits of each of the texture addresses tx and ty generated by the texture address generation unit 13 are replaced by the gate circuit 14 with a fixed value corresponding to the texture data. For example, in the case of a repeating pattern of "F", the upper 4 bits of tx and ty are 0 and 0, respectively. As a result, as shown in FIG. 8, as the texture address, the address TA (1 −−−, 0 −−−), which exceeds the storage range of the texture data of “F”,
TB (0 ---, 1 ---), TC (1 ---, 1 ---
Even if −) is given, each upper 4 bits are replaced with “0”, so that each address is TA ′ (0 −−−, 0 −−−).
-), TB '(0 ---, 0 ---), TC' (0 ---
-, 0 ---)), resulting in FIG.
It is possible to assign a repeating pattern of "F" as shown in FIG. Similarly, if the upper 4 bits of the address are respectively set to "1, 0", the pattern assigned by TA, TB, TC shown in FIG.
The repetitive pattern of “T” is as shown in FIG.

Such a gate circuit 14 is shown in FIG.
It can be configured as 0. The mask circuit 21 is
Masking is performed by replacing the upper bits of the output from the texture address generation unit 13 with "0". If the texture coordinates are 11 bits, the pattern size of the texture data and the mask circuit 24 for each x and y coordinate.
The relationship with the output of is as shown in Table 2 below. Here, the numbers in the upper column are output bit numbers of the mask circuit 21,
"0" part is the masked bit, bx is the address x
This means passing the bit as it is. If the bit “0” portion of the output of the mask circuit 21 is replaced with the texture pattern number by the OR gate 22,
It is possible to select 2 ⁸ = 256 types of texture data of size 8 × 8.

[0027]

[Table 2]

Further, for example, instead of the OR gate 22 of FIG. 10, by using the adder 23 as shown in FIG. 11, it is possible to offset the texture address by a designated value. Desired texture mapping is possible even if the sizes of the regions are different.

As described above, in the case of using a repeating figure as texture data, in extreme cases, if only the minimum repeating unit is stored as texture data, texture coordinates can be specified at arbitrary coordinates for texture mapping. The memory capacity can be saved and the texture coordinates can be easily specified.

In the above embodiments, the range of mapping is described as a triangle, but it goes without saying that other polygons such as a quadrangle may be mapped.

[0031]

As described above, according to the present invention,
Depending on how to give texture coordinates to fill coordinates,
Since the texture data can be arbitrarily enlarged, reduced, rotated, and deformed and allocated, various modes of mapping can be performed, and only the standard pattern need be stored in the texture storage means. So
The memory capacity can also be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of a texture mapping device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure of mapping processing by the apparatus.

FIG. 3 is a diagram showing an example of fill coordinates and texture coordinates given to the apparatus.

FIG. 4 is a diagram showing a relationship between a texture memory and texture coordinates in the same device.

5 is a diagram showing a mapping result corresponding to each texture coordinate in FIG. 4;

FIG. 6 is a diagram showing an example of a cube and a texture pattern mapped to the cube.

FIG. 7 is a diagram showing a change in pattern when the cube is rotated.

FIG. 8 is a diagram showing an example of an effective use method of a texture memory.

FIG. 9 is a diagram showing an example of mapping using the same memory.

FIG. 10 is a diagram showing a specific example of a gate circuit.

FIG. 11 is a diagram showing another example of the gate circuit.

FIG. 12 is a diagram for explaining texture mapping.

[Explanation of symbols]

1 ... Texture mapping unit, 2 ... Image memory, 3 ... C
PU, 4 ... Frame memory, 5 ... Texture memory, 1
DESCRIPTION OF SYMBOLS 1 ... CPU interface, 12 ... Fill address generation part, 13 ... Texture address generation part, 14 ... Gate circuit, 15 ... Selector, 16 ... Control part, 17 ... Data processing part.

Claims (1)

[Claims] 1. A frame storage means for storing a two-dimensional display data of a three-dimensional object on a display screen, a texture storage means for storing texture data to be mapped on the surface of the three-dimensional object, and texture mapping. By inputting fill coordinates and texture coordinates defining a range, a fill address of each pixel inside the range defined by the fill coordinates is sequentially generated, and a texture address corresponding to the generated fill address is generated. Mapping means for reading texture data from the storage location of the texture storage means specified by the generated texture address and storing it in the storage location of the frame storage means specified by the fill address. Texture mapping device.