Computer graphics processing and selective visual display system – Computer graphics processing – Graphic manipulation
Reexamination Certificate
1999-09-01
2002-12-03
Luu, Matthew (Department: 2672)
Computer graphics processing and selective visual display system
Computer graphics processing
Graphic manipulation
C345S629000, C345S634000
Reexamination Certificate
active
06489967
ABSTRACT:
This application is based on Patent Application No. 10-248281 filed on Sep. 2, 1998 in Japan, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image formation apparatus and an image formation method, more specifically to an image formation apparatus and an image formation method for performing a translucent calculation in a short time when displaying a scene on a display screen in which a translucent object and a background object of the translucent object overlap in a virtual space.
2. Description of the Related Art
Recently, with the progress of image depiction technology in three-dimensional computer graphics, a variety of techniques are developed for depicting objects in a virtual space such as used in a three-dimensional game apparatus and the like. In this kind of technology, since formation of a translucent object is useful, there is known a translucent depiction technology as described, for example, in Japanese Patent Application Laying-open Nos. 10-187951(1998) (corresponding to U.S. patent application Ser. No. 09/142,658) and 8-185543(1996). The disclosure of U.S. patent application Ser. No. 09/142,658 is incorporated herein by reference. In the following, translucent depiction and a prior art translucent depiction technology will be described.
FIG. 1
is a diagram for explaining translucent depiction in a virtual space.
In the virtual space of
FIG. 1
, three objects exist which are represented as a polygon A
600
, a polygon B
610
and a translucent polygon T
620
, respectively. Here, the object represented by the polygon T
620
is a translucent object. The polygon A
600
and the polygon B
610
are present in a background of the translucent polygon T
620
. The scene in the virtual space is depicted on a two-dimensional screen
650
. A pattern corresponding to the polygon A
600
is a polygon A
660
in the two dimensional pattern. A pattern corresponding to the polygon B
610
is a polygon B
670
in the two-dimensional pattern, and a pattern corresponding to the translucent polygon T
620
is a translucent polygon T
680
of the two-dimensional pattern. Since the translucent polygon T
620
is translucent, when viewed from the screen
650
side, the polygon A
600
and the polygon B
610
present in the background can be seen through. Therefore, on the screen
650
, the two-dimensional polygon A
660
and the two-dimensional polygon B
670
present in the background of the two-dimensional translucent polygon T
680
are required to be depicted to be seen through. As described above, depiction of a polygon present in the background of a translucent polygon or the like or another object in a virtual space to be seen through is referred to as translucent depiction.
FIG. 2
is a diagram showing an example of a frame buffer (memory)
130
storing a depiction data depicted on the screen
650
of FIG.
1
.
In
FIG. 2
, the depiction data corresponding to the two-dimensional polygon A
660
is data
760
of the polygon A
660
, the depiction data corresponding to the two-dimensional polygon B
670
is data
770
of the polygon B
670
, and the depiction data corresponding to the two-dimensional translucent polygon T
680
is data
780
of the translucent polygon T
680
. The respective depiction data are stored in a unit of pixel
700
,
710
or the like. In the data
780
of the translucent polygon T, there are a background polygon A reference part
720
which is necessary to be referred to for performing translucent depiction and a background polygon B reference part
730
which overlaps with the data of the polygon B
670
present in the background and is necessary to be referred to for performing translucent depiction. For these overlapping parts, after pixel data in the data
760
of the polygon A
660
is read, and calculation for translucent depiction is performed between the pixel data and a corresponding pixel data in the data
780
of the translucent polygon T
680
, and then it is necessary to write depiction data of the calculation result at the position of the above-described pixel. This is the same as for the data
770
of the polygon B
670
and a background B reference part
730
.
FIG. 3
is a diagram showing a construction example of a prior art image formation apparatus for performing translucent depiction.
In
FIG. 3
, as described in the following, a depiction part
100
shown by the dotted line for performing depiction processing has the frame buffer
130
, a translucent calculation part
105
, a controller
125
, a pre-depiction processing part
101
, a texture memory
120
and the like. The frame buffer
130
is a data holding circuit (storage device) for storing the depiction data, and is composed, for example, of a DRAM. The controller
125
performs switching or the like between read from the frame buffer
130
and write to the frame buffer
130
. The depiction part
100
reads a depiction data (hereinafter referred to as “background data”)
108
of background object necessary for translucent calculation from the frame buffer
130
through the controller
125
and outputs it to the translucent calculation part
105
for performing translucent calculation. The translucent calculation includes various color calculations necessary for translucent depiction. The pre-depiction processing part
101
inputs polygon data
102
of translucent object from the CPU part
140
, and then performs pre-depiction processing including texture mapping, and outputs a pixel data
104
resulting from pre-depiction processing to the translucent calculation part
105
. The translucent calculation part
105
executes translucent calculation on inputted background data
108
and pixel data
104
, and writes the resulting depiction data
106
in the frame buffer
130
for each pixel through the controller
125
. The CPU part
140
inputs as necessary an instruction of an operator (not shown) from an operation part
150
, and outputs as necessary a sound data to a sound output part
160
. The texture memory
120
connecting to the pre-depiction processing part
101
is a data holding circuit holding circuit storing data of the result of performing texture mapping on polygons and the like. Data of the frame buffer
130
is outputted to a picture output part
170
through the controller
125
, and finally displayed on a screen of a display apparatus such as a CRT
180
.
FIG. 4
shows an example of time chart schematically showing read of background data
108
in the translucent calculation part
105
of
FIG. 3
from the frame buffer
130
, translucent calculation, and write of depiction data
106
after calculation into the frame buffer
130
.
As shown in
FIG. 4
, in the translucent calculation part
105
of the prior art image formation apparatus, read of background data Dn (R(Dn)) was performed, then translucent calculation (F(Dn)) was performed, and finally write of depiction data Dn* (W(Dn*)) was performed. That is, any of read of background data from the frame buffer
130
, and write of depiction data to the frame buffer
130
is not performed continuously, but performed pixel by pixel. Therefore, an overhead due to switching occurs between read of background data and write of depiction data at each pixel. Read from the frame buffer
130
and write to the frame buffer
130
is high in efficiency when it is performed continuously, however, is low in efficiency when it is performed for each pixel. That is, a total processing time when performing for each pixel is longer than a total processing time when performing continuously. Therefore, the prior art image formation apparatus in which read from the frame buffer
130
and write to the frame buffer
130
are performed for each pixel required a longer processing time.
Further, a total T=T
R
+T
F
+T
W
of a time T
R
required for read of background data, a time T
F
required for translucent calculation, and a time T
W
required for write of depiction data for each pixel is required and it is repeated for each pixel. That is, in
Fitch Even Tabin & Flannery
Good-Johnson Motilewa
Luu Matthew
Namco Limited
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