JPH01200481A - Picking method for three-dimensional graphic - Google Patents

Abstract

PURPOSE:To quickly pick a three-dimensional graphic as a program of a graphic processor GPU by using a hardware for comparing a Z value which is outputted from the GPU and a Z value in a Z buffer, and applying interruption to the GPU, when they are coincided and informing it. CONSTITUTION:An operator instructs one point on the display surface by using a pointing device, by which XY coordinate positions are shown. Subsequently, a Z comparison control part 3 leaves only a Z value of a Z buffer 6 of an address corresponding to these XY coordinate values (Xv, Yv), and clears all Z values of other coordinate positions. Next, a Z value which s generated from a GPU 1 and the Z value of the Z buffer 6 are compared, but in all other points, the Z value of the Z buffer 6 is larger, therefore, a control part 3 can execute a control so that write to a frame buffer FB 4 and the Z buffer 6 is not executed. In such a state, when coordinate positions which are outputted from the GPU 1 go to (Xv, Yv, Zv), the control part 3 detects the coincidence and applies the interruption to the GPU 1 through an interruption signal line 31, and informs that these coordinate position points show a graphic derived by a three- dimensional graphic.

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention converts three-dimensional graphic information (in this specification, "figures" include figures and images) into a two-dimensional plane in a form that is easy for humans to understand. The present invention relates to a method for surprising a three-dimensional figure displayed on a display surface using a three-dimensional figure display device.

"Prior Art" When displaying a three-dimensional figure on a two-dimensional plane such as the display surface of a cathode ray tube display, it is necessary to display the figure with shading or to remove hidden surfaces (lines).
display in a form that is easy for humans to understand.

FIG. 2 is a block diagram showing an example of a conventional device. In the figure, (1) is a graphic processor (hereinafter abbreviated as GPU), (2) is a graphic database, (3) is a Z comparison control unit, and (4) is a Frame buffer (hereinafter abbreviated as FB), (5) is a display device (hereinafter abbreviated as CRT)
, (6) is a Z buffer.

Data of graphics to be displayed on the CRT (5) is stored in a graphics database <2). For example, one polygon (in this case, a polygon on one plane in three dimensions) can be transferred to a CRT.
(5), the coordinate position of each vertex of the polygon (coordinate position regarding the XYZ orthogonal coordinates with the Z-axis in the direction perpendicular to the display surface of the CRT (5)) and the brightness at which the polygon should be displayed. (B value, however, the B value in this specification includes color information in the case of color display) is stored. The GPU (1) inputs this type of data from the graphic database (2) and sends this polygon (to be precise, the projection of this polygon onto the XY plane) to the CRT (5) using a raster scan method. Generate the B value to be displayed and write it to F B (4). F B (4)
is the XY of each pixel (pixel, minimum unit pixel)
The B value is written using the coordinate position as an address.

For example, if the B value inside the polygon is Bl (for example, green) and the B value outside is 0 (black), B1 is written at the XY coordinate position inside the polygon, and O is written at the XY coordinate position outside the polygon. A polygon filled in green is displayed on the CRT (5).

To display hidden surface removal, the Z comparison control unit (3) refers to the data in the Z buffer (6) and executes writing to F B (4). Z values are stored in the Z buffer (6) using XY coordinate positions as addresses. G.P.
U In (1), calculate the Z value corresponding to the XY coordinates of the polygon, compare it with the Z value of the same XY point in the Z buffer, and if the latter is smaller (assuming a left-handed coordinate system. Below) same), that part of this polygon is already F B
(4) means that it is hidden by the part of another figure stored in the CRT (5).
) indicates that it must not be displayed. GPU (1
) is compared with the Z value in the Z buffer at the same XY coordinate value, and the Z value in the polygon is compared with the Z value in the Z buffer (6). Only when the value is smaller, the B value of the polygon in that part is written to F B (4), and the Z value of the polygon is written to the Z buffer (6).

By the way, it is difficult for an operator to use a pointing device to indicate a figure displayed on a CRT (5) and for the machine to recognize which drawing is indicated.
This function is often used in machine communication and is called BIC, but the conventional BIC method requires a large amount of data processing and therefore takes a long time, making it unsuitable for man-machine communication. I couldn't say yes. That is, the conventional Bick method is executed based on clipping processing, assuming a rectangular parallelepiped containing points defined by XY coordinates specified on the display screen and arbitrarily set Z values, and storing it in the figure database (2). The state of intersection between the three-dimensional polygon data and this rectangular parallelepiped is checked, and if they intersect, it is determined that there is a possibility that the data of this polygon is the specified data.

Such processing is performed on all polygon data while changing the Z value of the rectangular parallelepiped, and for rectangular parallelepipeds that intersect with one or more Booligons, the one with the smallest Z value is selected, and the same Z value is
When two or more polygons intersect, the volume of the rectangular parallelepiped is reduced and one polygon is selected.

``Problems to be Solved by the Invention'' The conventional methods described above place a large load on the GPU for processing, require a large amount of processing time, are slow to respond after the operator starts, and are difficult for both man and machine. - There was a problem that it was not suitable for communication.

The purpose of the present invention is to solve this problem and provide a method that enables high-speed processing using a simple algorithm for three-dimensional figures.

"Means for solving the problem" In this invention, the Z value output by the GPU and the Z value in the Z buffer are
When the values match, the GPU
using hardware that interrupts and informs G
This was realized as a PU program.

"Operation" When the operator reads the Z buffer using the XY coordinates of the point indicated by the pointing device as an address, the Z value of that point of the indicated figure is obtained, so the three-dimensional figure containing the same coordinate position is indicated. This figure can be detected by comparing it with the Z value output from the GPU.

"Embodiments" Examples of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing an embodiment of the present invention. In the figure, the same reference numerals as in FIG. 2 indicate the same or corresponding parts.
1) represents an interrupt signal line.

When performing a big operation, the brightness of each pixel is stored in FB (4) at an address corresponding to the XY coordinate position of that pixel, and CRT (5) reads and displays the contents of FB (4). ing. Further, the Z value of the XY coordinate point is stored in the address position corresponding to the XY coordinate of the Z buffer (6).

The operator uses a pointing device to point to a point on the display surface. This means that the XY coordinate position is specified. The Z comparison control unit (3) calculates the Z value of the address corresponding to this XY coordinate position (X=Xv, Y=Yv).
All Z values at other coordinate positions are cleared (maximized), leaving only the binary value (Z=Zv) in buffer (6).

Next, the Z comparison control unit (3) compares the Z value generated from the GPU (1) and the Z value of the Z buffer (6).
Since the Z value of Z buffer (6) is larger in all other respects, it is possible to control so that F B <4) and writing to Z buffer (6) is not performed. GPU (1
) The coordinate position output from X=Xv, Y=Yv, Z=
When Zv, the Z comparison control unit (3) detects a match and issues an interrupt to the GPU (1) via the interrupt signal line (31), confirming that the three-dimensional figure containing this coordinate position point is the desired figure. Let me know.

In this way, the graphic is easily completed.

The method of this invention can be effectively applied in the field of CAD when constructing a man-machine interface with good response characteristics.

"Effect of the Invention" As described above, according to the present invention, the GP
With the simple process of interrupting U, a three-dimensional figure can be quickly read.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an apparatus used in a conventional method. (1) is GPU (graphics processor), (
2) is the figure database, (3) is the Z comparison control unit, (4
) is an FB (frame buffer), (5> is a CRT (display device), (6) is a Z buffer, and (31) is an interrupt signal line. Note that the same reference numerals in each figure indicate the same parts.

Claims (1)

[Claims] Based on a graphic database that stores graphic data, and graphic data read from this graphic database, the graphic (graphic, A graphics processor that determines the Z value (hereinafter referred to as Z value) and brightness information (hereinafter referred to as B value) of the XY coordinate point of each pixel (minimum unit pixel) constituting a figure (including an image); A Z buffer that stores Z values using point information as addresses; a frame buffer that stores B values using XY coordinate point information as addresses; and a Z value determined by the graphic processor and the same XY coordinate position in the Z buffer. and means for updating the contents of the Z buffer and the frame buffer according to the result of this comparison;
Using a three-dimensional graphics processing device having means for displaying the contents of the frame buffer on a display device, an operator uses a pointing device to display the contents of the frame buffer on the display surface.
In a three-dimensional figure picking method that allows the machine to recognize which figure is the figure whose Y coordinate position is specified, the above Z buffer is read out using the XY coordinates of the point specified by the operator with the pointing device as an address, and all points other than that point are read out. The step of clearing the contents of the Z buffer at all addresses of the graphics processor compares the Z values of all graphics generated by the graphics processor with the Z values of the same XY coordinates in the Z buffer, and if they match, the graphics processor A method for picking a three-dimensional figure, comprising the step of applying an interrupt.