JP2674127B2 - 3D graphics processor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional graphic processing apparatus, and more specifically, it performs predetermined coordinate conversion processing on world coordinate system data and predetermined clip processing. The present invention relates to a three-dimensional graphic processing device that obtains device coordinate system data by performing the above.

<Prior Art and Problems to be Solved by the Invention> Conventionally, three-dimensional graphic processing apparatuses having various configurations have been provided.
Flow of 3D graphics processing based on 3D graphics standard (hereinafter referred to as viewing pipeline)
Has been adopted.

As the viewing pipeline, the standard PHIGS (Programmer's Hierarchical Inter
Active Graphics System) compliant and standard GKS-3D (Graphical Kernel System-3D)
It is generally compliant with.

More specifically, the viewing pipeline conforming to the above-mentioned standard PHIGS, as shown in FIG. 5, applies the modeling conversion processing to the structure element data defined in the modeling coordinate system so that each structure is processed. Data in the world coordinate system (hereinafter abbreviated as world coordinate system data) is generated by combining the element data.

Then, the field of view conversion processing is performed on the world coordinate system data to obtain data in the view reference coordinate system (hereinafter abbreviated as view reference coordinate system data), and the view reference coordinate system data is transferred to the projection viewport. Data in a normalized projection coordinate system (hereinafter, abbreviated as normalized projection coordinate system data) is obtained by performing projection processing and clipping processing based on the projection viewport. After that, by performing clipping processing based on the workstation window and workstation conversion processing on the normalized projection coordinate system data, data in the device coordinate system (hereinafter abbreviated as device coordinate system data) is obtained, and the CRT is used. A visual display is performed by a display device or the like.

The process until the world coordinate system data is obtained is executed in a processing part independent of the workstation, and the process after the visual field conversion process is executed in the process part depending on the workstation.

As shown in FIG. 6, the viewing pipeline conforming to the standard GKS-3D described above performs data conversion in a normalized coordinate system by performing a normalization conversion process on primitive data defined in the world coordinate system. Hereinafter, the data will be abbreviated as normalized coordinate system data), subjected to segment conversion processing as necessary, and then subjected to normalized clipping processing to extract only necessary portions of the normalized coordinate system data.

Then, the view reference coordinate system data is obtained by subjecting the extracted normalized coordinate system data to the view conversion process, and the view reference coordinate system data is clipped based on the view volume and the projection viewport is projected. To obtain normalized projection coordinate system data. After that, clip processing based on the workstation window for the normalized projection coordinate system data,
Also, the device coordinate system data is obtained by performing the workstation conversion process, and is visually displayed on the CRT display device or the like.

The processing until the above-mentioned normalized coordinate system data is obtained is performed in a processing section independent of the workstation,
The processing after the field-of-view conversion processing is performed in the processing portion that depends on the workstation.

As is clear from the above description, in the viewing pipeline conforming to any of the above standards, the world coordinate system data or the normalized coordinate data is generated in the processing portion independent of the workstation, and the workstation The device coordinate system data is generated by sequentially performing the view conversion process, the clip process based on the view volume or the viewport, the projection process, the clip process based on the workstation window, and the workstation conversion process after clipping in the processing part that depends on Has been done.

Therefore, when generating device coordinate system data based on world coordinate system data, it is essential to perform clip processing based on the view volume or viewport, and clip processing based on the workstation window, increasing the number of clip processing times. Because
There is a problem that the overhead as a whole viewing pipeline becomes large, and eventually the graphic display speed decreases.

<Objects of the Invention> The present invention has been made in view of the above problems, and it is possible to greatly simplify the clip processing in the workstation-dependent portion, and to greatly improve the graphic display speed. An object is to provide a graphic processing device.

<Means for Solving the Problem> To achieve the above object, a three-dimensional graphic processing apparatus according to the present invention comprises a projection means for projecting a view volume onto a projection viewport, a projection viewport and a workstation window. It has area extraction means for extracting the common area and clipping means for performing clipping processing based on the common area.

However, the area extracting means may be one that extracts a common area based on the projection viewport and the workstation window set on the normalized projection coordinate system and normalizes the extracted common area. preferable.

Further, it is preferable that the clipping means performs the homogeneous coordinate clipping process based on the normalized common area.

Further, it is preferable that the three-dimensional graphic processing device conforms to the three-dimensional graphics standard PHIGS or GKS-3D.

<Operation> In the case of the three-dimensional graphic processing apparatus having the above-described configuration, the predetermined coordinate conversion processing is performed on the world coordinate system data, and the predetermined clip processing is performed to obtain the device coordinate system data and display the data. In the case of obtaining three-dimensional graphic data, the area extracting means extracts a common area between the projection viewport and the workstation window, the view volume is projected onto the projection viewport by the projection means, and then the clipping means. By performing the clipping process on the basis of the extracted common area, it is possible to obtain three-dimensional graphic data corresponding to the area to be actually displayed.

When the area extracting means extracts the common area based on the projection viewport and the workstation window set on the normalized projection coordinate system and normalizes the extracted common area, By performing the clipping process on the basis of the extracted and normalized common area, it is possible to obtain three-dimensional graphic data corresponding to the area to be actually displayed.

If the clipping means performs the homogeneous coordinate clipping process based on the normalized common area, the view volume clipping process and the workstation window clipping process are performed only by performing the homogeneous coordinate clipping process. It is possible to obtain the same result as the case where the treatments are sequentially performed.

Further, even when the three-dimensional graphic processing device complies with the three-dimensional graphics standard PHIGS or GKS-3D, the same operation as above can be achieved.

<Example> Hereinafter, an example will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram showing a main part of an embodiment of the three-dimensional graphic processing apparatus according to the present invention. The area setting data set by an external operation is used as an input for the projection viewport on the normalized projection coordinate system. A viewport setting unit (1) for setting (see FIG. A) and a window data holding unit for holding a workstation window area (see FIG. 3B) preset corresponding to the normalized projection coordinate system. (2), a common area extraction unit (3) that extracts a common area (see FIG. 3C) between the projection viewport and the workstation window area on the normalized projection coordinate system, and the common area is three-dimensional. A normalized projection unit (4) for projecting onto a region (see FIG. 4) normalized so that the coordinate values are between -1 and 1, and the extracted and normalized region ( (See FIG. 4), a clip processing unit (5) that performs a homogeneous coordinate clip process based on the common area projected, and a workstation conversion unit (6) that performs a workstation conversion process on the clipped data. ) And is composed of.

FIG. 1 is a schematic diagram showing the viewing pipeline of the present invention, showing only the workstation dependent portion.

That is, the view reference coordinate system data is generated by subjecting the world coordinate system data to the field-of-view transformation process, and the projection transformation process from the view volume to the projection viewport is performed. Device coordinate system data is obtained by performing clipping processing based on the common area and further performing workstation conversion processing.

Therefore, for many world coordinate system data,
It is necessary to perform the necessary conversion processing for each, but with regard to clip processing, it only has to be performed once based on the common area between the projection viewport and the workstation window, which reduces the number of clip processing executions. Accordingly, the time required for processing the graphic data can be shortened, and the overall graphic display speed can be increased.

More specifically, in a graphic display device, there are a world coordinate system that defines a target figure and a device coordinate system for performing visual display, and it is a rectangular parallelepiped that defines the display limit in the device coordinate system. A workstation window (see FIG. 3B) having a rectangular shape, and a projection viewport having a rectangular parallelepiped shape that defines the display area of the target graphic (see FIG. 3A).
See). Therefore, the target graphic is visually displayed only in the common area of the projection viewport and the workstation window (see FIG. 3C).

Therefore, if the coordinate coordinate clip processing is performed based on the common area between the projection viewport and the workstation window defined on the normalized projection coordinate system, the view volume clip processing and the workstation window clip processing are sequentially performed. The same result can be obtained as in the case. After that, by further performing the workstation conversion process, the finally displayable device coordinate system data can be obtained.

As is clear from the above description, if the common area between the projection viewport and the workstation window is extracted once, then only the clip processing is performed using the extraction result. Since the same data as when the workstation window clipping process is sequentially performed can be obtained, the process can be simplified as a whole, and the graphic display speed can be improved.

<Effect of the Invention> As described above, in the first invention, the common area between the projection viewport and the workstation window is extracted in advance, and the extracted common area is projected in a state in which the view volume is projected onto the projection viewport. Since the clip processing based on the above is performed, the clip processing can be simplified as a whole, and the graphic display speed can be improved, which is a unique effect.

In the second invention, since the common area extracted based on the projection viewport and the workstation window is normalized, it is only necessary to perform the clip processing by the normalized common area, and the clip processing is simplified as a whole. Therefore, it is possible to achieve the unique effect that the graphic display speed can be improved.

The third aspect of the invention has a unique effect that the same result as when the view volume clipping process and the workstation window clipping process are sequentially performed can be obtained only by performing the homogeneous coordinate clipping process.

The fourth aspect of the invention has a unique effect that the clip processing in the workstation-dependent part can be greatly simplified without impairing the state of conforming to the three-dimensional graphics standard.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a viewing pipeline according to the present invention, FIG. 2 is a block diagram of essential parts showing an embodiment of a three-dimensional graphic processing apparatus of the present invention, and FIGS. 3 and 4 are clip processings. 5 is a schematic diagram showing a conventional example of a viewing pipeline compliant with the standard PHIGS, and FIG. 6 is a schematic diagram showing a conventional example of a viewing pipeline compliant with the standard GKS-3D. Fig. (1) ...... Viewport setting unit, (2) …… Window data holding unit, (3) …… Common area extraction unit, (4) …… Normalization projection unit, (5) …… Clip processing unit, ( 6) …… Workstation conversion unit

Claims (4)

(57) [Claims] 1. A three-dimensional graphic processing apparatus for subjecting world coordinate system data to predetermined coordinate conversion processing and predetermined clip processing to obtain device coordinate system data, and projecting a view volume onto a projection viewport. Projection means, area extraction means (3) (4) for extracting a common area between the projection viewport and the workstation window, and area extraction means (3)
A three-dimensional graphic processing apparatus comprising: a clipping unit (5) for performing a clipping process based on the common area extracted in (4). 2. A region extracting means (3) (4) extracts a common region based on a projection viewport and a workstation window set on a normalized projection coordinate system, and normalizes the extracted common region. The three-dimensional graphic processing apparatus according to claim 1, which is to be realized. 3. A three-dimensional graphic processing apparatus according to claim 1, wherein the clipping means (5) carries out the homogeneous coordinate clipping processing based on the normalized common area. 4. A three-dimensional graphic processing apparatus according to claim 1, which complies with the three-dimensional graphics standard PHIGS or GKS-3D.