Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Reexamination Certificate
2000-09-15
2003-04-01
Nguyen, Phu K. (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
Reexamination Certificate
active
06542151
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to three-dimensional image display techniques and, more particularly, to a technique for displaying three-dimensional images by using polygons.
2. Description of the Related Art
One of the known techniques for displaying three-dimensional images is to use polygons. Generally, in the image displaying technique using polygons, the surface of a three-dimensional object having a complicated configuration is divided into polygons, and a pattern or a design, which is referred to as a “texture”, is pasted on each polygon.
In this polygon-based image display technique, moving pictures can appear very realistic while requiring only a small amount of data compared to graphic images, such as photographs. Additionally, this polygon-based technique makes it possible to display three-dimensional images. Accordingly, with these advantages, the polygon-based techniques are widely used in game machines in which images must be quickly moved in response to player's instructions. In view of this background, research is being conducted on the polygon-based image display techniques so as to reduce a load on game machines and also to display realistic images while providing three-dimensional effects.
Along with the use of polygons, attention is sometimes focussed on the advantage of displaying realistic images while requiring only a small amount of data. For example, if moving pictures created by using a large number of cell images are replaced by moving pictures using polygons, not only the load on the machines, but also human resources required for creating cell images, can be reduced.
However, polygon-based moving pictures appear very realistic because of its development purposes, and images consisting of edges and solid portions, which are generally unique to the moving pictures created by cell images, cannot be expressed very well by this polygon-based display technique. Accordingly, by using the polygon-based image display technique, moving pictures similar to those created by cell images cannot be obtained.
SUMMARY OF THE INVENTION
Accordingly, in view of this background, it is an object of the present invention to increase the range of applicability of a polygon-based image display technique by making it possible to add edges to polygon-based three-dimensional images.
In order to achieve the above object, according to one aspect of the present invention, there is provided a polygon-image display method for use in an apparatus for displaying a polygon image on a predetermined display unit, the polygon image being generated by combining basic polygons for rendering a three-dimensional object. The polygon-image display method includes the step of rendering a similar polygon, the reverse surface of which faces the obverse surface of the basic polygon. The similar polygon is larger than the basic polygon and has a similar shape to the basic polygon, and forms a pair with the basic polygon.
The above-described polygon-image display method utilizes the feature unique to the polygon-based image display technique. That is, for preventing image flickering, it is determined that polygons with their reverse surfaces facing a certain viewpoint are not seen. According to the above method, since an image of the similar polygon is displayed together with an image of the basic polygon, the entire three-dimensional object represented by a combination of the basic polygons is covered with the similar polygon, the reverse surface of which faces the obverse surface of the basic polygon. With this arrangement, the similar polygon which is pasted on the basic polygon and is located behind the basic polygon can be displayed as the edge of the three-dimensional object. In other words, the portion of the similar polygon outside the basic polygon can be used as the edge of the basic polygon.
As is seen from the foregoing description, since the similar polygon must be located outside the basic polygon, it is determined to be larger than the basic polygon. Additionally, the similar polygon used as an edge of the basic polygon has substantially the same thickness, and thus, the similar polygon has a similar shape to the basic polygon. Because of this figure, the similar polygon can be easily generated from the basic polygon data.
To promote edge enhancement of the similar polygon, a different texture from that of the basic polygon is pasted on the similar polygon.
In this case, the similar polygon may be created by being calculated based on the basic polygon data when a polygon image is displayed, or similar polygon data may be prepared to form a pair with the basic polygon data. In the second case, the similar polygon data may be stored in a storage unit, and may be displayed based on the similar polygon data. Also in the second case, calculations are not required for indicating the similar polygon, and thus, this technique can be extensively used not only for displaying predetermined images, but also for game fields in which images must be quickly displayed in response to player's instructions.
According to the foregoing polygon-image display method, the center of gravity of the similar polygon may coincide with that of the corresponding basic polygon. With this arrangement, the widths of the portion of the similar polygon outside the basic polygon can be consistent, and can thus be suitably used as an edge of the basic polygon.
In the aforementioned method, the order of rendering the basic polygon and the similar polygon is not particularly restricted. Either of the polygons may be rendered first, or both the polygons may be rendered simultaneously. If the similar polygon is rendered first followed by rendering of the basic polygon, the basic polygon image is provided with a perimeter edge. That is, if a plurality of similar polygons or basic polygons overlap, the polygon closest to the viewpoint is preferentially displayed. Accordingly, by rendering the similar polygon first and then by pasting the basic polygon on the similar polygon, the portion of the similar polygon outside the adjacent basic polygons is located behind the basic polygons and is thus unseen on the polygon image. As a result, only the perimeter edge of a three-dimensional object represented by a set of basic polygons is displayed as viewed from the current viewpoint, thereby providing edge effects.
The above-described method may further include the steps of: detecting normal vectors of other basic polygon which are adjacent to each of the vertices of the basic polygon corresponding to the similar polygon; determining a unit vector having a direction identical to the direction of a sum vector of the normal vectors; setting the forward end of the unit vector to an edge point for each of the vertices of the basic polygon as an original point; and shifting the vertices of the similar polygon to the edge points.
With this arrangement, the vertices of the similar polygon which determine the width of the portion outside the basic polygon can be located away from the vertices of the basic polygons by the corresponding unit vectors. It is thus possible to maintain a constant width of the edge to be drawn by the outside portion of the similar polygon, thereby facilitating edge enhancement from an aesthetic point of view.
The above-described steps may be prepared when the data for rendering the similar polygon is created. In this case, by displaying only the similar polygon and the basic polygon, a sharp edge can be displayed without the need for performing specific calculations.
In the aforementioned method, the unit vector may be multiplied by a predetermined coefficient so as to determine a displacement vector, and the forward end of the displacement vector may be set to be the edge point for each of the vertices of the basic polygon as an original point, thereby shifting the vertices corresponding to the similar polygon to the edge points. With this arrangement, it is possible to draw each edge with a predetermined width by the portion of the similar p
Minami Tatsuma
Murayama Takanori
Bachman & LaPointe P.C.
Konami Corporation
Nguyen Phu K.
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