JPS60256874A - Triangle dividing system of closed pattern - Google Patents

Abstract

PURPOSE:To decrease the number of using memories and to improve the data transfer performance by showing the data on the coordinate positions of a closed pattern at the apex positions of some continuous triangles. CONSTITUTION:When a closed pattern is divided into triangles and stored, the triangles adjacent to each other on a memory are also adjacent as patterns with a side shared in many cases. In such a case, two of three apexes are equal between both adjacent triangles. Therefore it is possible to omit the data corresponding to two apexes among three of the low-order triangle on the memory. Thus a command showing the continuous triangles and one apex display a triangle. For instance, flags 50-52 are all set at ''0'' with a command 31 which defines first a triangle. While two of flags 50-52 is equal to 1 with the rest one set at ''0'' with commands 32-35 which define a trinangle that shares two spexes with the immediately preceding triangle. Then one of flags 50-52 is equal to ''0'' with the rest wo set at 1 with a command that defines a triangle sharing an apex with the immediately preceding triangle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to graphic processing technology using a computer, and particularly to a triangulation method for closed figures suitable for a three-dimensional graphic processing system.

[Background of the invention] Since it was expressed as a series of several vertex coordinates, closed figures that intersect with themselves (Figure 2 a), closed figures that are not convex (Figure 2 b), and 3-dimensional closed figures are In this case, there can be closed figures whose vertices do not lie on the same plane as data, and each of these has a different algorithm for figure processing, and one closed figure falls into the above classification. The problem is that it requires complicated calculations to determine whether it is true or not, and the processing time is long.

Also, there is no known method of dividing a closed figure into several triangles and storing them in advance. A triangle never intersects with itself, and is always a convex figure except when 3 vertices are on a straight line, and all vertices are always on the same plane. 83 Judgments when the vertices are on a straight line It's relatively easy. However, storing closed figures as triangles has the disadvantage of increasing the amount of data.The 68-sided example must be divided into at least 6 triangles, and the number of vertices to be stored is 18 ( 3iiri.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a triangulation method for closed figures that allows triangulation of closed figures to be carried out without increasing the amount of stored 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, two of the three vertices of these triangles 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. Figure 4 shows an overall diagram of the graphic processing system.

The graphic data is stored in a graphic data file 1.

When an operator requests display of a figure through the input device 5, the computer 3 interprets the signal from the input device 5 and accesses the figure 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. The closed figure IO is divided into five triangles 11-15. Triangle 11 has three vertices 21-23, triangle 12 has three vertices 22-24, triangle 13 has three vertices 23-25, triangle 14 has three vertices 24-26, and triangle 1 has three vertices 22-24.
5 has three vertices 25 to 27, respectively. [Closed figure] 0 is stored in the memory of the figure file 1 in the following order. Command 31 indicating the beginning of triangle 11.
Vertex 21 seat #A41. Coordinates 42 of vertex 22, vertex 23
Coordinates of 43. Command 32 indicating the beginning of a continuous triangle 12. Coordinates of vertex 24, 1iI) 44, command 33 indicating the start of continuous triangle 13
．． Vertex 25 seat #45. Command 34 indicating the beginning of a series of triangles 14. Coordinates 46 of vertex 26. Command 35 indicating the beginning of a continuous triangle 15. Coordinates 4 of vertex 27
7゜Figure 6 shows the command format. The command has a length of 16 bits, and the 0th to 2nd bits 50 to 52 are flags indicating the continuous state of triangles, the 3rd to 7th bits 53 are unused,
Bits 54 from No. 1 to No. 15 are an operation code indicating that it is a triangle.

When the flag 50 is l, it indicates that the first vertex of the immediately preceding triangle on the 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. When the flag 52 is 1, it indicates that the third vertex of the immediately preceding triangle on the memory is also the third vertex of the triangle indicated by this command.

In the command that first defines a triangle (e.g. 31), flags 50 to 52 are all O, and the command to sew a triangle that shares two vertices (one side) with the previous triangle (e.g. 32 to 35) ), any two of flags 50 to 52 are 1 and the other one is O. For commands that define a triangle that shares one vertex with the previous triangle, flags 50~
One of 52 is O and the other two are 1. 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 reduced, 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.
This has the effect of improving data transfer performance. Generally, in the case of a closed figure with n vertices, the amount of data is as follows. Including commands, n=20.16
In the case of bit coordinate values and a three-dimensional closed figure example, the reduction was about 57%.

[Brief explanation of the drawing]

Fig. 1 shows an example of a closed figure, Fig. 2 shows an example of a closed figure that is difficult to process, and Fig. 3 shows an example of triangulation of the closed figure. FIG. 4 shows an example of a graphic processing system, FIG. 5 shows an example of triangulation of a closed figure according to the present invention, and FIG. 6 shows an example of the shape of a command indicating a triangle. 11-15... Triangles obtained by dividing a closed figure, 31-35
...Commands that indicate triangles, 50-52...Triangle/Kuni No. 2 Mouth Palpitation) (b) No. 3 Ku No. 4

Claims (1)

[Claims] A storage device capable of storing data related to an object such as shape, coordinate position and two colors, a transmission path capable of inputting and outputting data to the storage device, and a transmission path capable of inputting data from the transmission path, interpreting said data regarding an object;
In a graphics processing device consisting of a display device capable of displaying a figure corresponding to the data in a manner that can be recognized by an operator, data regarding the coordinate position of a closed figure (plane) is displayed by displaying the closed figure in the form of several consecutive triangles. A triangulation method for closed shapes that is characterized by representation using vertex positions.