Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Reexamination Certificate
2003-02-14
2004-06-15
Vo, Cliff N. (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
Reexamination Certificate
active
06750861
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an information processing device and method thereof, and a transmission medium, and more particularly relates to an information processing device and method thereof and a transmission medium by which an amount of information for an object to be processed is reduced in such a manner that processing can be carried out at high speed.
With information processing devices such as computer games, various three-dimensional figures (objects) are represented, with the objects being possible to be changed in various states.
FIG. 1
is a block diagram showing an example of a configuration of such kind of information processing device. In this example, a CPU
11
carries out various calculations such as coordinate transformations, light source calculations or vector arithmetics etc., as well as controlling of each part. Further, to the CPU
11
, there are connected a main bus
12
that carries out data transfer at a comparatively high speed and a sub-bus
13
that carries out the data transfer at a comparatively low speed, via which data can be exchanged. A CD-ROM drive
14
is connected to the sub-bus
13
so that various data or programs can be read out from a CD-ROM as a recording media installed in the CD-ROM drive
14
using instructions of the CPU
11
.
A main memory
15
and a GPU (Graphics Processing Unit)
16
are connected to the main bus
12
. The main memory
15
stores data such as data read our from the CD-ROM driver
14
and data as computation results of the CPU
11
. The GPU
16
reads out data from the main memory
15
as required, carries out rendering processing, and stores the processed data in a VRAM (Video Random Access Memory)
17
as pixel data. The GPU
16
further reads out pixel data stored in the VRAM
17
and supplies this data to a D/A converter
18
. The D/A converter
18
converts the pixel data supplied from the GPU
16
from a digital signal to an analog signal for being outputted to a monitor (not shown) as a video signal.
With this kind of information processing device, a prescribed object is represented with triangular polygons as the units. One triangle is composed of three vertexes, and coordinate data for these three vertexes is therefore required as data representing this triangle. For example, as shown in
FIG. 2
, when a ribbon-shaped object
21
is formed from triangles
22
—
1
to
22
—
8
(in this drawing, each triangle is shown separately to make the description easier), if the data for each triangle is taken to be expressed as {Pa, Pb, Pc}, the data for this object
21
can be expressed as Triangle {P
0
, P
1
, P
2
}+Triangle {P
1
, P
2
, P
3
}+Triangle {P
2
, P
3
, P
4
}+Triangle {P
3
, P
4
, P
5
}+Triangle {P
4
, P
5
, P
6
}+Triangle {P
5
, P,
6
, P
7
}+Triangle {P
6
, P
7
, P
8
}+Triangle {P
7
, P
8
, P
9
}.
The number of items of data required to define an object formed using N triangles is therefore 3N.
On the other hand, as shown in
FIG. 3
, after, for example, the first triangle
22
—
1
is formed using vertexes P
0
, P
1
and P
2
, the next triangle
22
—
2
can be formed if the vertex P
3
is specified. The triangles for the following stages can then be expressed in a similar manner by sequentially specifying the vertexes P
4
to P
9
one at a time. This is to say that, with the exception of the first triangle
22
—
1
, one triangle can be expressed using one vertex. Such a data format by which a figure (object
21
) where triangles are linked in a ribbon shape is expressed as a series of successive points is referred to as a “Triangle Strip” (hereinafter abbreviated to “strip” according to situations). Data for an object
21
as a strip can then be expressed as a Triangle Strip {P
0
, P
1
, P
2
, P
3
, P
4
, P
5
, P
6
, P
7
, P
8
, P
9
}.
When an object
21
is defined using a series of successive points in this way, the number of items of required data is 3+(N−1)=N+2, and the amount of data (information) can be reduced compared with that in the case shown in FIG.
2
.
Further, as shown in
FIG. 4
, a fan-shaped object
31
can be formed by making vertexes P
1
to P
5
correspond to vertex P
0
. In this case, one triangle can also be represented by one vertex as, Triangle Fan {P
0
, P
1
, P
2
, P
3
, P
4
, P
5
}. This kind of data format is referred to as a triangle fan (Triangle Fan) (hereinafter abbreviated to “fan” according to situations).
Incidentally, a single triangle can be drawn using data for coordinates for three vertexes, three vertex colors and three normal vectors. A description will now be given with reference to
FIG. 5
of, for example, the process for drawing the object
21
shown in
FIG. 3
with individual triangles taken as the units. First, in step S
101
, the CPU
11
reads out three-dimensional coordinate data, color data and a normal vector corresponding to a prescribed vertex of the three vertexes of one triangle from the main memory
15
. In step S
102
, the read out three-dimensional coordinate data is transformed to coordinates in a virtual space.
In step S
103
, the CPU
11
carries out perspective transformation of the three-dimensional coordinate data that has been converted in step S
102
into two-dimensional coordinate data. Namely, the three-dimensional coordinates of the triangle put in the virtual space are converted to coordinates for a state viewed in two dimensions (a state viewed on a monitor). Following this, in step S
104
, the CPU
11
outputs the two-dimensional coordinate data obtained in step S
103
to the GPU
16
.
In step S
105
, the CPU
11
calculates the luminance at each vertex from the position and direction of a light source in virtual space, with color data corresponding to the calculation results of step S
105
being outputted to the GPU
16
in step S
106
.
In step S
107
, a determination is made as to whether or not processing for all (three) of the vertexes for one triangle is complete. When it is determined that there still exist vertexes that have not yet been processed, the process returns to step S
101
and processing for the next vertex is carried out. When it is determined in step S
107
that processing is complete for all of the vertexes, the process proceeds to step S
108
to go to processing of the GPU
16
.
In step S
108
, the GPU
16
draws the triangle formed by three vertexes through Gouraud shading with the data corresponding to the three vertexes supplied by the CPU
11
. In step S
109
, a determination is made as to whether or not drawing for all of the triangles is complete (whether or not drawing of the object
21
is completed). When it is determined that there still exist triangles that have not yet been drawn (drawing of the object
21
is not completed), the process returns to step S
101
and the same processing is carried out on other triangles of FIG.
3
.
When it is determined in step S
109
that drawing is complete for all of the triangles (drawing of the object
21
is complete), the processing is complete.
The processing occurring at the GPU
16
in step S
108
will now be further described. For example, if normal vectors
51
—
1
to
51
—
3
at each vertex A, B and C of a triangle
61
to be processed are taken to be directed in directions shown in
FIG. 6
, a normal vector
51
—
4
at the center point D of the triangle
61
is interpolated by the GPU
16
from these normal vectors. The triangle
61
therefore has a bulge toward a central part. Therefore, when light giving illumination from a light source
41
is considered, as shown in
FIG. 7
, Gouraud shading has to be carried out in such a manner that the triangle
61
is brighter in the center part thereof and becomes darker toward the edges.
Gouraud shading, however, is processing that only interpolates color. Therefore, for example, when each vertex is given with the same color, the triangle
61
becomes completely painted out as shown in
FIG. 8
, and its acc
Frommer William S.
Frommer Lawence & Haug LLP
Kessler Gordan
Vo Cliff N.
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