Abstract:
An apparatus for displaying three-dimensional graphics, is disclosed, which comprises: a reader for reading coordinate data of objects to be displayed; another reader for reading coordinate data of a complete floor to be displayed; a generator for generating coordinate data of each partial floor disposed under a lower surface of each object; an input device for inputting viewpoint position data; and a generator for generating display data to which a hidden surface process have been applied on the basis of the coordinate data of the objects, the complete floor, and the partial floors and the viewpoint position data.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to method and apparatus for displaying three-dimensional graphics, and in particular, to those that allow an object to be displayed in accordance with physical laws. 
     2. Description of the Related Art 
     In a conventional three-dimensional representation, when a three-dimensional object is disposed and displayed in a three-dimensional space including a floor, if the three-dimensional object is disposed at a position higher than the floor, the three-dimensional object is displayed in such a manner that the three-dimensional object floats above the floor. 
     However, the related art has the following disadvantages. 
     A first disadvantage is that it is difficult to intuitionally perceive the object. 
     This is because the expression that an object floats in a space contradicts the real world in which objects are put on a floor by gravity and is lack of reality. 
     A second disadvantage is that a process for adding a partial floor to only objects that float in the space becomes complicated. 
     This is because it is necessary to determine whether or not each object floats in the space. 
     A third disadvantage is that detailed data for objects and process treating the data are required. 
     This is because it is difficult to inhibit looking up an object that floats in the space from lower viewpoint, and the data needed to be displayed when the object is looked up from the lower viewpoint must be provide. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide apparatus and method for displaying three-dimensional graphics that prevent an object from being displayed in the state that it simply floats in the space. 
     According to an aspect of the present invention, there is provided an apparatus for displaying three-dimensional graphics, comprising: means for reading coordinate data of objects to be displayed; means for reading coordinate data of a complete floor to be displayed; means for generating coordinate data of each partial floor disposed under a lower surface of each object; means for inputting viewpoint position data; and means for generating display data to which a hidden surface process have been applied on the basis of the coordinate data of the objects, the complete floor, and the partial floors and the viewpoint position data. 
     In the apparatus, the coordinate data of each partial floor may be generated in such a manner that the distance between the partial floor and a lower surface of the object corresponding thereto is longer than the distance between the complete floor and an object disposed thereon. 
     These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of a best mode embodiment thereof, as illustrated in the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram showing the structure of a three-dimensional graphics displaying apparatus according to an embodiment of the present invention; 
         FIG. 2  is a flow chart for explaining the operation of the three-dimensional graphics displaying apparatus according to the embodiment of the present invention; 
         FIG. 3  is a schematic diagram showing an example of floors and objects that the three-dimensional graphics displaying apparatus according to the embodiment of the present invention displays; 
         FIG. 4A  is a schematic diagram showing a complete floor shown in  FIG. 3  that an output device displays on the basis of display data that the three-dimensional graphics displaying apparatus according to the embodiment of the present invention generates; 
         FIG. 4B  is a schematic diagram showing an object and a partial floor viewed from a viewpoint shown in  FIG. 3 ; and 
         FIG. 5  is a block diagram showing the structure of a three-dimensional graphics displaying apparatus according to another embodiment of the present invention. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     According to the present invention, in three-dimensional computer graphics, when a three-dimensional object (hereinafter simply referred to as object) is disposed and displayed in a three-dimensional space that includes a complete floor, a partial floor is always disposed below the object so that the object appears to be supported by the partial floor, to prevent that the object appears to be float in the space if the bottom of the object disposed in the space does not contact the complete floor. In such a manner, an object is disposed in accordance with the physical law of the real world. As a result, the reality of the three-dimensional computer graphics is improved and they are well intuitionally perceived. 
     However, the distance between the object and the partial floor that is always disposed at a lower portion of the object is predetermined so that the partial floor is disposed at a position lower than the upper surface of the complete floor when the object is disposed on the complete floor. As a result, the partial floor is hidden when the object is put on the complete floor. 
     In  FIG. 3 , data for a partial floor corresponding to each object is added to original data for each object and a complete floor. As a result, an object disposed adjacent to a complete floor appears to be put on the complete floor. On the other hand, an object that is disposed apart from the complete floor appears to be put on a partial floor. 
     In such a manner, partial floors are added below all the objects. Thus, an unnatural graphics in which an object appears to simply float in the space is prevented from being displayed. Thus, the graphics can be naturally perceived. 
     Referring to  FIG. 1 , the three-dimensional displaying apparatus according to the embodiment of the present invention comprises a storing apparatus  1  that stores written data and reads the stored data, a data processing apparatus  2  operated corresponding to a program, and an output apparatus  3  that displays a three-dimensional graphics. 
     The storing apparatus  1  contains a solid structure coordinate data storing device  11 . The data processing apparatus  2  comprises a display data generating device  21  and a viewpoint managing device  22 . The output apparatus  3  comprises a display device. 
     These devices operate as follows. 
     The solid structure coordinate data storing device  11  stores coordinate data of objects to be displayed and coordinate data of a complete floor. 
     The display data generating device  21  reads the coordinate data of the objects and the coordinate data of the complete floor from the solid structure coordinate data storing device  11  and adds coordinate data of partial floors each disposed at a position apart from the lower surface of each object to be displayed by a predetermined distance of ε as data for the partial floor. 
     For an object to be disposed adjacent to the complete floor, it is predefined that the lower surface of the object is disposed at a position higher than the upper surface of the complete floor by a predetermined distance of δ. In this case, the value of δ is smaller than the value of ε. 
     The viewpoint managing device  22  manages viewpoint position data. 
     Thereafter, the display data generating device  21  generates display data using coordinate data and viewpoint position data referenced from the viewpoint managing device  22  and outputs the generated display data to an output device  31 . 
     The output device  31  displays three-dimensional graphics on the basis of the display data that is input from the display data generating device  21 . 
     Next, with reference to the block diagram shown in  FIG. 1  and a flow chart shown in  FIG. 2 , the overall operation of the embodiment of the present invention will be described. 
     First of all, the display data generating device  21  reads coordinate data of objects to be displayed and coordinate data of a complete floor from the solid structure coordinate data storing device  11  (at step S 101 ). Thereafter, the display data generating device  21  adds coordinate data of partial floors each disposed at a position lower than the lower surface of each object to be displayed by a predetermined distance of ε (at step S 102 ). Thereafter, the display data generating device  21  references the latest viewpoint position data from the viewpoint managing device  22  (at step S 103 ). The viewpoint position data varies time after time. Thereafter, the display data generating device  21  generates display data for each object, the complete floor, and each partial floor viewed from a viewpoint on the basis of the coordinate data for the objects, the complete floor, and the partial floors to be displayed and the viewpoint position data (at step S 104 ). Thereafter, the display data generating device  21  outputs the generated display data to the output device  31  (at step S 105 ). 
     Thus, the output device  31  displays three-dimensional graphics on the basis of the display data that is input from the display data generating device  21 . 
     Next, with a concrete example, the operation of the embodiment will be described. 
     As shown in  FIG. 3 , it is assumed that in a three-dimensional space in which there are a complete floor A and two objects, one object B 1  is disposed adjacent to the complete floor A and the other object C 1  is disposed at an upper position apart from the complete floor A. First of all, the display data generating device  21  reads coordinate data of the complete floor A, the object B 1 , and the object C 1  from the solid structure coordinate data storing device  11  (at step S 101 ). Thereafter, according to the embodiment, partial floors are disposed at lower portions of the respective objects. In other words, a partial floor B 2  for the object B 1  and a partial floor C 2  for the object C 1  are added. In other words, the display data generating device  21  generates and adds coordinate data of the partial floors B 2  and C 2  so that they are disposed at positions lower than the lower surfaces of the objects B 1  and C 1  by a predetermined distance of ε (at step S 102 ). Thereafter, the display data generating device  21  references the latest viewpoint position data from the viewpoint managing device  22  (at step S 103 ). Thereafter, the display data generating device  21  generates partial data for a visible part of the complete floor A, partial data for a visible part of the object B 1 , partial data for a visible part of the object C 1 , and partial data for a visible part of the partial floor C 2  as display data viewed from a viewpoint in consideration of the overlaps of the complete floor A, the objects B 1  and C 1 , and the partial floors B 2  and C 2  on the basis of the complete floor A, the objects B 1  and C 1 , the partial floors B 2  and C 2 , the coordinate data, and the viewpoint position data. In this case, since the partial floor B 2  is hidden below the complete floor A, the partial floor B 2  is not displayed. Thus, the visible partial data for the partial floor B 2  is not included in the display data (at step S 104 ). Thereafter, the display data generating device  21  outputs the generated display data to the output device  31  (at step S 105 ). The output device  31  displays three-dimensional graphics as shown in  FIGS. 4A and 4B  on the basis of the display data that is input from the display data generating device  21 . 
     In addition, as shown in  FIG. 5 , the functions and methods performed by the display data generating device  21  and the viewpoint managing device  22  of the data processing device may be embodied by a computer  2 B that executes a program that the computer  2 B reads from a record medium  4  or a program that the computer  2 B receives from a server  7  of an ASP (Application Service Provider)  6  through a network  5 . 
     As was described above, the present invention takes the following effects. 
     A first effect is that three-dimensional computer graphics in which a three-dimensional object is disposed and displayed in a three-dimensional space including a floor can be intuitionally perceived. 
     This is because each object always appears to be displaced on a floor rather than to be floating in the space, similar to the real world in which the gravity exists. 
     A second effect is that a partial floor can be added to only an object that requires it without need to determine whether or not each object is disposed on a complete floor. 
     This is because although partial floors are added to all objects, with a hidden surface process performed for all the floors and all the objects upon generation of display data, a partial floor of an object disposed adjacent to the complete floor is hidden by the complete floor. 
     A third effect is that display data for each object which is looked up from a lower viewpoint may be omitted. 
     This is because all the objects are disposed on a floor which hide the bottom of the objects. 
     Although the present invention has been shown and described with respect to the best mode embodiment thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions, and additions in the form and detail thereof may be made therein without departing from the spirit and scope of the present invention.