Computer graphics processing and selective visual display system – Computer graphics processing – Graph generating
Reexamination Certificate
1998-05-15
2001-05-29
Vo, Cliff N. (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Graph generating
C345S441000
Reexamination Certificate
active
06239809
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processing device based on a computer, and more particularly, to an image processing device whereby the process of generating colour data for frames comprising a plurality of polygons can be conducted efficiently in a short period of time, or this process can be conducted efficiently in a short period of time using a small hardware composition, and it relates to a method for same and a storage medium for storing image processing programs for same.
2. Description of the Related Art
Image processing technology based on computers is used in simulation devices and game devices. Normally, data for polygons to be drawn on a screen and colour data for each pixel in these polygons are determined from image data generated by the simulation or game sequence program, and this colour data is stored in a frame buffer memory corresponding to the screen pixels. An image is then displayed on a display device, such as a CRT, or the like, in accordance with the colour data in the frame buffer memory.
The process of determining the aforementioned polygon data is usually carried out by a geometry processing section, and the process of determining colour data for each pixel is generally conducted by a rendering processing section.
The polygon data produced by the geometry processing section generally comprises vertex data. The colour data for pixels in a polygon is determined by interpolation of the parameter values contained in the vertex data.
However, in some cases, a frame may contain a plurality of polygons which overlap with each other, and in this event, only the portions of polygons which are foremost in the screen are displayed, whilst the portions of polygons which are covered by another polygon are not displayed. Therefore, conventionally, a Z-value buffer memory corresponding to the pixels in each frame is provided, and when the colour data for a pixel is written into the frame buffer memory, the Z-value for that pixel is written into a region of the Z-value buffer memory corresponding to the pixel. The operation of deciding whether or not a pixel in a polygon processed subsequently is positioned in front of a pixel already written to the memory is carried out by comparing their respective Z values. Alternatively, as a further algorithm, the colour data may always be written to the frame buffer starting from the polygon which is rearmost in the frame. The Z-value described above means depth value indicating a depth in a screen. For the convenience, the depth value is referred to z-value here in after.
However, when a plurality of polygons overlap with each other, it may occur that, after colour data for a pixel positioned to the rear of the frame has been calculated and colour data for that pixel has been written to the frame buffer memory, colour data for a pixel in a different polygon, positioned in front of the aforementioned pixel, is calculated and this colour data is written to the same address in the frame buffer memory. Therefore, the rendering process for the pixel positioned to the rear, which has already been carried out, becomes completely purposeless, thus causing the efficiency of the rendering process to decline.
Furthermore, in a conventional method, the rendering process for a particular pixel in a particular polygon is conducted simultaneously with the interpolation of parameters in the vertex data and the interpolation of Z values. Therefore, the hardware composition for this section becomes very large. Consequently, if it is sought to process a plurality of these sections in parallel, the hardware will become colossal, which will be impractical. This is one factor which restricts improvements in the efficiency of rendering.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide an image processing device, method and storage medium for storing programs for same, whereby image processing using a computer can be conducted more efficiently.
It is a further object of the present invention to provide an image processing device, method and storage medium for storing programs for same, whereby, in image processing, rendering for generating colour data for pixels can be conducted more efficiently.
According to the present invention, the aforementioned objects are achieved by providing, in an image processing device comprising a rendering processing section for generating colour data for pixels which are to be displayed from polygon data including, at least, a polygon ID, positional co-ordinates data and parameters for generating colour data attributed thereto, the image processing device comprising: a polygon buffer memory for storing the polygon data; and
a frame buffer memory for storing colour data for the pixels in a frame; wherein the rendering processing section comprises: a first processing section for generating Z values (depth values) indicating the depth in a screen of pixels in respective polygons, for a plurality of polygons located in the frame, and storing the Z values for pixels to be displayed on the screen and the polygon IDs corresponding thereto in a Z value buffer memory, in which the Z values for pixels in the frame are stored; and a second processing section for generating colour data from the parameters attributed to the polygon IDs stored in the Z value buffer memory, for each pixel in the frame; wherein the colour data for each pixel generated by the second processing section is stored in the frame buffer memory.
By means of this composition, firstly, the Z values for the pixels are determined for all polygons in a frame and the pixels that are to be displayed on the screen are determined according to their Z values, whereupon colour data can be generated for the pixels to be displayed in the frame. Therefore, it is possible to avoid wasteful generation of colour data for pixels in overlapping regions.
Furthermore, in the present invention, by providing a plurality of levels in the first processing section, Z values can be generated for a plurality of pixels in parallel. Furthermore, by providing a plurality of levels in the first processing section, Z values for pixels can be generated for a plurality of polygons in parallel.
According to the present invention, the aforementioned objects are also achieved by providing, in an image processing method comprising a rendering process step for generating colour data for pixels which are to be displayed from polygon data including, at the least, a polygon ID, positional co-ordinates data and parameters for generating colour data attributed thereto, wherein the rendering process step comprises: a first processing step for generating Z values (depth values) indicating the depth in a screen of pixels in respective polygons, for a plurality of polygons located in the frame, and storing the Z values for pixels to be displayed on the screen and the polygon IDs corresponding thereto in a Z value buffer memory, wherein the Z values for pixels in the frame are stored; and a second processing step for generating colour data from the parameters attributed to the polygon IDs stored in the Z value buffer memory, for each pixel in the frame, and storing the generated colour data for each pixel in the frame buffer memory.
According to the present invention, the aforementioned objects are also achieved by providing, in a computer-readable storage medium storing a program for causing a computer, which comprises, at least, a central processing device for performing calculations and a frame buffer memory for storing colour data for pixels in a frame, to execute an image processing routine comprising a rendering process whereby colour data for pixels which are to be displayed is generated from polygon data including, at the least, a polygon ID, positional co-ordinates data and parameters for generating colour data attributed thereto; wherein the programs comprise a program for causing a computer to execute: a first processing routine for generating Z values (depth values) indicating the depth in a
Morioka Seisuke
Yasui Keisuke
Dickstein , Shapiro, Morin & Oshinsky, LLP
Sega Enterprises Ltd.
Vo Cliff N.
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