JPS63271580A - Graphic data transfer system - Google Patents

Abstract

PURPOSE:To reduce the amount of data transfer and to facilitate data control by providing a lane command for the shading display of the curved surface of a three-dimensional figure and a plane command for displaying a plane cut by a polygon, a curved surface, etc., as different commands. CONSTITUTION:A plane command for the brightness interpolating shading display of a curved surface, a plane command for normal interpolating shading display, a plane command for displaying a surface on an original plane cut by the polygon, curved surface, etc., with given brightness, and a plane command for calculating brightness from a given normal and performing display are provided as different commands, and geometric shape definition and display definition data are put together in one command. Namely, commands 2 and 3 are divided according to the kinds of the shading display method and display object surfaces and then a selection command for them is not necessary, thereby facilitating data control.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of transferring graphic data defined in a computer using computer graphics technology to a display device equipped with a CRT or the like, and in particular, The present invention relates to a graphic data transfer method suitable for shading display of a three-dimensional figure composed of a combination of planes and planes.

[Conventional technology]

Conventionally, as a method of displaying each face of a polyhedron that approximates a three-dimensional surface using computer graphics technology on a display device such as a CRT, 7 Olay, Fundamentals Opken Interactive Computer Graphics by Pan Dam. (Addison Unisley Publishing Company, 1982), pp. 580-584 (J.

D, Fole7 and A, Van Dam:
F'undamentalBof In-terao
tive Computer Graphics,
Addison - Wesle7 Publishing
Company (1982)pp, 5ao-584)
As described in , there are three types of shading methods: constant, luminance interpolation, and normal interpolation.

On the other hand, work is underway to standardize the method for transmitting graphic data necessary for displaying and defining graphics. Regarding two-dimensional figures, currently GKS (Gra-physical
Kernel S7S75te is the world standard. Regarding the standardization of three-dimensional figures, GKS-3D and PH
I G S (Programmer'''s Hler
aromatic InteractiveGraph
There are two proposals (iog 5tard), which are currently under discussion. Information Processing Society of Japan, Graphics Interface and Standardization Seminar Materials @GKS-3
D and IQBS' (September 17, 1985), pages 20 to 24, and the same document 'PHIGS', pages 10 to 14 and pages 19 to 20. GMS-5P and PHIGS inherit the two-dimensional concept, and the idea is to separate the commands that define the geometry of the surface from the commands that define the display method such as display color.

Note that in GKS-3D and PHIGS, the surface display method is only constant shading, and luminance interpolation and normal interpolation shading are not considered.

In addition, “@GRIP-n overview book” written by Daikin Industries, Ltd.
Pages 5 to 11 and page 18 show a method of transferring luminance interpolation shading data in addition to constant shading. Again, the constant shading data is transferred using a separate command from the surface geometry data, and which shading data to transfer is specified using the selection command.

Furthermore, in Japanese Patent Application No. 61-28024, after receiving a polyhedral approximation surface command for displaying a curved surface using brightness interpolation or normal interpolation shading, flatness is determined.
[Problem to be solved by the invention] First, in the above-mentioned prior art, geometric shape definition data and display method definition are used. The idea is that data is transferred using separate commands. Conventionally, the target was mainly two-dimensional figures, and the display method was often changed depending on the meaning of one figure (the figure's display object), so we defined the display method such as the command that defines the geometric shape of the surface and its display color. Separate commands would have reduced the amount of data and made it easier to change the display method. However, when displaying a three-dimensional figure, the display density generally changes for each part of a curved surface and for each surface of a plane depending on the direction of the surface. At this time, if the geometry definition command and display method definition command are separate commands, they will always be transferred as a pair.

It is also necessary to simultaneously transfer commands or data indicating that they are a pair. Therefore, the amount of data transferred increases.

Also, if you want the recipient of the command to be able to remember this, and then modify the memorize command with the modify command, both the geometry definition command and the representation definition command can be used. must be able to be corrected.

To do this, a command or data that pairs the geometry definition command and display method definition command is required as described above, and a function to modify the geometry definition command and display method definition command based on this is required. implementation is required, which complicates data management.

In addition, in the case of two-dimensional figures, they are only figures on a plane,
There are no geometrically different shapes.

However, in the case of three-dimensional figures, two types of surfaces with different geometric meanings coexist: a surface for approximating a three-dimensional curved surface and a surface for displaying the surface itself in a three-dimensional plane. appears. Therefore, apart from the geometry definition command and display method definition command, the above conventional method:
A selection command is transferred each time to indicate which one is available. Therefore, the amount of transferred data increases. Furthermore, on the side that receives the transferred data and performs display processing, there are two stages of branching to the processing program, one based on the geometry definition command and the other based on the selection command, which complicates the processing.

Therefore, in order to make the process as simple as possible using the conventional method, it is important to transfer all data using as few types of commands as possible.

This can be achieved with a total of three commands: one geometry definition command and two display method definition commands for brightness interpolation and normal interpolation. However, the display method definition command at this time is the display method definition command for curved surface display even in the case of flat display.

This results in unnecessary data being transferred, which increases the amount of transferred data. Furthermore, up to that hawk, the processing for flat display and curved display is the same, and the display processing time becomes longer. In order to speed up the processing, flatness determination processing is required.

The present invention aims to reduce the amount of data transferred, thereby shortening the transfer time and reducing the data storage area.
Another object of the present invention is to provide a graphic data transfer method that eliminates the need for flatness determination processing and facilitates data management for display method selection determination and partial correction of storage commands.

[Means for solving problems]

The above purpose is to use the surface command to display a curved surface with brightness interpolation shading, the surface command to display normal interpolation shading, and to display a surface on a plane cut by an original polyhedron or curved surface with a given brightness. Separate commands are used for the surface command for folding and the surface command for calculating and displaying the brightness from the given normal.
This is accomplished by combining geometry definition and representation definition data into one command.

[Effect]

It is possible to divide the commands into commands according to the shading display method and the type of surface to be displayed, and there is also a method that eliminates the need for these selection commands, and a rounding method that transfers the data necessary for each command and its display method in the same command. , commands or data that pair geometry definition commands and display method definition commands are no longer required.

Furthermore, by selecting appropriate commands, the amount of data transferred can be reduced, and as a result, the command transfer time and command storage area can be reduced. Furthermore, since flatness determination processing is not necessary and geometric shape definition data and display method definition data can be handled at once, data management in displaying and deleting some graphical commands is facilitated.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are explanatory diagrams of an embodiment of the graphic data transfer method according to the present invention, in which FIG. The figure is an explanatory diagram of a figure to be displayed and a data transfer command in the case of normal interpolation shading display.

In FIGS. 1 and 2, 1 is a figure to be displayed created by cutting a spherical surface into 2,000 parallel planes, and 2, 3, 4.degree. 5 is a command format. Consider displaying this spherical part using luminance interpolation and normal interpolation shading. For this purpose, one spherical surface is divided into polyhedra and approximated. Further, the planes cut by the upper and lower spherical surfaces are each approximated and displayed as a polygon.

Now, let us consider, for example, that the spherical portion is a decahedron, and the upper and lower surfaces are approximated by decagons, as shown in FIGS. 1 and 2, for example. Here P, ~P,. sQ1~Q,. C is the approximate decahedron and the vertices of the decagon. In FIG. 1, engineering ~ engineering and J, ~J,. are the points P, ~P, Im and Q, ~Q, respectively. is the brightness on the spherical surface at .

Further, I and J are the brightness of the upper and lower planes, respectively. Also, in FIG. 2, s n1 to n. and m.

~m,. are the points P, ~P, respectively. and Q, ~Q,.

is the normal vector of the sphere at . Further, n and m are normal vectors of the upper and lower planes, respectively.

At this time, in FIGS. 1 and 2, the quadrilateral P1P
2Q2Q is a polygon that constitutes one face of a decahedron that approximates a curved surface. The decagon p, p2 to P1° is a polygon that approximates one of the planes cut by the spherical surface. The transfer of these polygon data is shown in Figures 1 and 2, respectively.
As shown in the figure, the following command format is used depending on the shading display method.

Now, let's consider displaying the image using luminance interpolation.

At this time, as shown in Figure 1, the quadrilateral P1 ''2 q2q,
The definition data is command format 2, and the decagon P, P2
9. .

P. Definition data is transferred in command format 3.

Command 2 is a polygon that approximates a curved surface, gives the brightness data of each vertex, and uses that data to linearly interpolate the brightness 1 degree data of each display point within the polygon to obtain and display the polygon, that is, the vertices. Instruction code PV indicating that it is a polygon with brightness
I, vertex number data (4 in this case) and each vertex x,
Data (X
l + Yl * Zl + K1) In this case, 1=1
~4, K, =I, , K2=I2. K,=J
2°K4=J1). On the other hand, command 3 is a polygon on a plane, and command code PS1. Vertex number data (10 in this case), plane brightness data, x, y, z of each vertex
Coordinate values (xi, y, zi) (in this case, 1 = 1 to 10
).

However, this is a decagon p, p2...P,. Assuming that the light source position and the viewpoint position are sufficiently far apart for the size of the decagon p, p2...P,. This is the case where the brightness appears to be uniform. In general, this assumption is not a practical limitation when displaying for confirming the shape of a three-dimensional figure.

Also, when displaying the display target figure 1 by normal interpolation, use a separate command as shown in Figure 2, and enter the square "l P2 Q
2 Ql is command format 4, with decagons p, p2...
"10 is transferred in command format 5. Command 4 is a polygon that approximates a curved surface, gives normal vector data of each vertex, and linearly interpolates the normal vector of each display locus within the polygon from that data. instruction code PVN indicating that the polygon is a polygon with vertex normal vectors, the number of vertices data (4 in this case), and each The X, Y, Z coordinate values of the vertex and the X, Y, Z co-component data of the normal vector (X,
, Yl.

Zl + xl t 71 + zl ) (in this case, i=1 to 4). Command 5 is a polygon on a plane, and the brightness of each display point within the polygon is determined and displayed from the normal vector of the given surface, the light source, and the direction of the viewpoint, that is, a polygon with surface normal vector. Instruction code PSN indicating that it is a polygon, number of vertices data (10 in this case), x, y, z components of the normal vector of the surface (xtL
z ), the X, Y, Z values of each vertex (Xl, Yl.

2□) (in this case, 1=1 to 10).

Figures 1 and 2 show the case of a combination of curved surfaces and planes, but when a three-dimensional figure is originally composed of a combination of only planes, the surface commands that define each surface are used to display the shading at that time. Select and transfer command format 3 or 5 in FIGS. 1 and 2 depending on the law.

In addition, the polyhedral division is sufficiently finer than the curvature of a single surface,
If each face of the polyhedron can be regarded as a plane, it is transferred using command format 3 or 5 even if the polygon is a curved surface.

〔Effect of the invention〕

As described above, according to the present invention, the surface commands for displaying a curved surface with brightness interpolation shading, normal interpolation, and kneading are made into separate commands, thereby eliminating the need for conventional selection commands. Also,
By selecting appropriate commands depending on the curved surface or plane, the amount of display method definition data transferred can be reduced. As a result, command transfer time and command storage area can be reduced. This reduction effect increases as the number of vertices of a polygon increases, and the amount of transferred data can be reduced by a maximum of 1/6 in the case of luminance interpolation and 1/2 in the case of normal interpolation.

Furthermore, flatness determination processing is no longer necessary, and geometric shape definition data and display method definition data can be handled all at once.
It is possible to provide a graphic data transfer method with excellent functions, such as facilitating data management in displaying graphics and deleting some graphics, while eliminating the drawbacks of the prior art.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a figure to be displayed and a data transfer command in the case of luminance interpolation shading display in an embodiment of the present invention, and FIG. 2 is an explanation of a figure to be displayed and a data transfer command in the case of normal interpolation shading display. It is a diagram. 1... Figure to be displayed 2... Polygon with vertex brightness command 3... Polygon with surface brightness command 4... Polygon with vertex normal vector command 5... Polygon with surface normal vector Command P, ~P,. +Q1~Q
,. ...Polygon vertex work, ~ work,. ,J,~J,.・・・
- Vertex brightness r, J... surface brightness m, ~m,. ,n,~n,. ... Vertex normal vector m
, n... Surface normal vector.

Claims (1)

[Claims] 1. In a graphic data transfer method for displaying a three-dimensional figure on a display device using computer graphics technology, a surface command and a surface command for displaying a curved surface of the three-dimensional figure in shading are provided. , a three-dimensional figure data transfer characterized by reducing the amount of data transferred and facilitating data management by using separate commands for displaying planes cut by polyhedrons, curved surfaces, etc. method. 2. A graphic data transfer method according to claim 1, characterized in that geometric data and data for shading display are included in one command. 3. The graphic data transfer method according to claim 2, further characterized in that a surface command for displaying a curved surface in luminance interpolation shading and a surface command for displaying a curved surface in normal interpolation shading are separate commands. A graphic data transfer method that uses 4. In the graphic data transfer method described in claim 2, a command to define a plane to be displayed with a given brightness and a command to define a plane to be displayed by calculating the brightness from the normal vector of the given surface. A graphic data transfer method characterized by using each as a separate command.