JPH044628B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to graphic processing technology using a computer,
In particular, the present invention relates to a display figure definition method suitable for a three-dimensional figure processing system.

[Background of the invention]

Conventional closed figure data was expressed as a series of several vertex coordinates, as shown in Figure 1.
In the case of a closed figure that intersects with itself (Figure 2 a), a closed figure that is not convex (Figure 2 b), and a three-dimensional closed figure, the data includes closed figures whose vertices do not lie on the same plane. Each of these uses a different algorithm for figure processing, and it requires complicated calculations to determine which of the above classifications a single closed figure falls into, which has the disadvantage of taking a long processing time. It was hot.

A method is also known in which a closed figure is divided into several triangles and stored in advance. A triangle never intersects with itself, and is always a convex figure except when three vertices are in a straight line, and all vertices are always on the same plane. It is also relatively easy to determine when the three vertices are on a straight line. However, storing closed figures as triangles has the disadvantage that the amount of data increases. In the octagon example, it must be divided into at least 6 triangles,
The number of vertices to be memorized is 18 (Figure 3).

[Purpose of the invention]

An object of the present invention is to provide a display graphic definition method that can be implemented without increasing the amount of stored closed graphic data.

[Summary of the invention]

When a closed figure is divided into triangles and stored, adjacent triangles in the stored memory are also adjacent as figures and often share one side. In such a case, these triangles have two of their three vertices.
The vertices are the same, and therefore data corresponding to two of the three vertices of the lower triangle in the memory can be omitted. In the present invention, we have devised a command that indicates that a triangle is a continuous triangle, and a method that expresses one triangle using one vertex.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 4 to 6. FIG. 4 shows an overall diagram of the graphic processing system. Graphic data is stored in a graphic data file 1. When an operator requests display of a graphic through the input device 5, the computer 3 interprets the signal from the input device 5 and accesses the graphic data file 1. Graphic data is input to the computer 3 via the bus 2. The computer 3 interprets the graphic data, converts it into pixel data for display, and outputs it to the display device 4. The display device 4 arranges pixel data on its screen.

FIG. 5 shows an example of closed graphic data stored in the graphic file 1. Closed figure 10 has 5 triangles 1
It is divided into 1 to 15. Triangle 11 has three vertices 21 to 23, and triangle 12 has three vertices 22.
~24 Triangle 13 has 3 vertices 23-25 Triangle 14 has 3 vertices 24-26 Triangle 15 has 3 vertices 2
5 to 27, respectively. The closed figures 10 are stored in the memory of the figure file 1 in the following order. Command 31 indicating the start of triangle 11, coordinates 41 of vertex 21, coordinates 4 of vertex 22
2, coordinates 43 of vertex 23, command 32 indicating the start of continuous triangle 12, coordinates 4 of vertex 24
4. Command 33 indicating the start of continuous triangle 13, coordinates 45 of vertex 25, continuous triangle 14
Command 34 indicating the start of , coordinate 4 of vertex 26
6. Command 35 indicating the start of the continuous triangle 15; coordinates 47 of the vertex 27;

Figure 6 shows the format of the command. command is 16
In the bit length, the 0th to 2nd bits 50 to 52 are flags indicating the continuous state of a triangle, the 3rd to 7th bits 53 are unused, and the 8th to 15th bits 54 are an operation code indicating that it is a triangle. be.

When flag 50 is 1, it indicates that the first vertex of the immediately preceding triangle in memory is also the first vertex of the triangle indicated by this command. When the flag 51 is 1, it indicates that the second vertex of the immediately preceding triangle on the memory is also the second vertex of the triangle indicated by this command. flag 52
When is 1, 3 of the triangle immediately before in memory
The 3rd vertex indicates the 3rd vertex of the triangle indicated by this command.

Commands that define a triangle first (e.g. 31)
In this case, flags 50 to 52 are all 0, and in a command (e.g. 32 to 35) that defines a triangle that shares two vertices (one side) with the previous triangle, any two of flags 50 to 52 are 1. the other one is 0
It is. In a command that defines a triangle that shares one vertex with the immediately preceding triangle, one of flags 50 to 52 is 1 and the other two are 0. By using such a command, it is possible to store a minimum amount of data, including closed figures that intersect with itself.

According to this embodiment, since the amount of data transferred can be eliminated, there is an effect that the response time for the operator can be shortened.

〔Effect of the invention〕

According to the present invention, triangulation of a closed figure can be stored in approximately the same amount of storage space as when it is not divided, resulting in memory savings and improved data transfer performance. Generally, in the case of a closed figure with n vertices, the amount of data is the conventional method...3(n-2) vertices and the present method...n vertices. Including commands, n=20,
In the example of a three-dimensional closed figure with 16-bit coordinate values, the conventional method: 180 words (1 word = 16 bits) The present method: 78 words (1 word = 16 bits), a reduction of approximately 57%.

[Brief explanation of drawings]

Figure 1 is an example of a closed figure, Figure 2 is an example of a closed figure that is difficult to process, Figure 3 is an example of triangulation of a closed figure, Figure 4 is an example of a figure processing system, and Figure 5 is an example of a closed figure. is an example of triangulation of a closed figure according to the present invention, No. 6
The figure shows an example of a command shape that shows a triangle. 11-15...Triangles that divide closed figures, 31
~35...Command showing a triangle, 50~52...
...Flag indicating the continuous state of the triangle.

Claims (1)

[Scope of Claims] 1. Storage means for storing data defining a closed figure to be displayed, means for inputting and outputting the data to the storage means, and means for inputting and outputting the data to the storage means, In a display figure definition method in a figure processing device comprising a display means for displaying a corresponding figure, the closed figure to be displayed is divided into triangles, the definition data is created by an array of a plurality of the triangles, and the definition data is stored in the storage means. When one of the triangles to be stored and defined shares the vertex data that is the definition data of the previously defined triangle, the shared vertex data defined by the previous triangle is shared, and the vertex A display figure definition method characterized in that when data is not shared, vertex data is newly created as the definition data and stored in the storage means.