JPS6232571A - Chart display device - Google Patents

Abstract

PURPOSE:To decrease the discontinuity of a surface pattern due to the difference between the sampling interval on the surface of an object and that or a prescribed surface pattern by calculating the value of the surface pattern under consideration of the inclination of the surface of the object. CONSTITUTION:When supplying the desired pattern information about a point p1 on the plane of a three-dimensional object to display it as a display picture element d1 on a display screen S, the pattern information of the point p1 is calculated in accordance with the facing direction of the plane P at the point p1. Now, the write pattern information is calculated corresponding to the point p1, a second point p2 on the plane P is obtained in accordance with the angle of the inclination of the plane P against the point p1. A coordinate transformation is executed in accordance with a prescribed correspondence-relation between the picture S and a prescribed surface pattern information T defined on a prescribed coordinate system tx, ty, and the coordinate values of points a1 and a2 that correspond to the points p1 and p2 on the coordinate system tx, ty. Consequently, the average value of an surface pattern information in the area determined by the two points a1 and a2 as shown by the slant lines in the fugure is made to be the pattern information of the object's surface at the point p1 and is displayed the value of the display picture element d1 on the display screen S.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a surface display device for displaying the surface of a three-dimensional object in combinatorial graphics, and particularly to a surface display device for displaying the surface of a three-dimensional object in combi-compiled graphics. Color CRT for a 3D object
The present invention relates to a surface display device that displays high quality images on a display screen such as the following.

(Prior art and its problems) Conventional surface display devices use a technique called texture mapping. As an example of a conventional texture mapping method, surface pattern information representing the pattern or shape change desired to be expressed on the surface of a three-dimensional object is defined in advance in a coordinate system different from the object's coordinate space. , calculate the coordinate values of the corresponding points on the registered surface pattern by performing coordinate transformation according to a predetermined correspondence from the coordinate values of the points on the object surface corresponding to the six pixels on the display screen, and calculate the coordinate values of the corresponding points on the registered surface pattern. There is a method of displaying information on a surface pattern on a display screen as pattern information on the surface of an object. but,
Surface display devices using this method have the disadvantage that the surface pattern may be missing and displayed in a discontinuous manner on the object surface due to the short sampling interval on the object surface and the sampling interval on the surface pattern. are doing.

Furthermore, as another example of a conventional texture mapping method, the surface pattern and subsequent pixels are used as reference to obtain pattern information of a point on an object displayed at the previous pixel in the scanning line direction on the display screen. There is a method in which the average value of the values of the surface pattern corresponding to points on the surface of the object to be displayed is adopted as the value of the surface pattern to be displayed. However, although this method reduces the discontinuity of the surface pattern in the direction of the scanning line on the display screen, it still has the disadvantage that discontinuity of the surface pattern still occurs in the direction perpendicular to the scanning line. have.

Furthermore, as an example of another method used in conventional surface display devices, a plurality of surface patterns f1m corresponding to the sampling interval *a are registered in advance, and the previous pixel in the scanning line direction on the display screen is A surface pattern in which the value of the corresponding position should be displayed from the surface pattern according to the sampling interval indicated by the coordinate value of the point on the object displayed by and the change in the coordinate value of the point on the object surface displayed by the subsequent pixels. There is a method to adopt it as the value of . However, this method requires extra calculations because multiple surface patterns are determined in advance, and although the discontinuity of the surface pattern in the scanning line direction on the display screen is reduced as in the above method, It still has the disadvantage that discontinuities in the surface pattern occur in the direction perpendicular to the scanning line.

(Object of the Invention) In consideration of the above circumstances, the object of the present invention is to provide a method for displaying a three-dimensional object surrounded by a surface having arbitrary pattern information on a display screen. By calculating the value of the surface pattern taking into account the inclination of the object surface with respect to the screen surface, discontinuities in the surface pattern due to the difference between the sampling interval on the object surface and the predefined sampling interval on the surface pattern can be eliminated. It is an object of the present invention to provide a surface display method and device that can reduce the amount of light in all directions on a display screen.

(Structure of the Invention) According to the present invention, there is provided a screen, a surface information means for obtaining information on the surface of a three-dimensional object, a pattern information means for obtaining surface pattern information to be expressed on the surface, and each display pixel on the screen. display point calculation means for calculating a display point that is a point on the surface displayed on the surface; surface direction calculation means for calculating the orientation of the surface at the display point; A surface display device is obtained, comprising display pixel value calculation means for calculating a value of a pattern displayed in the corresponding display pixel from surface pattern information.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a conceptual diagram illustrating a surface display method according to an embodiment of the present invention. In the figure, when desired pattern information is given on one point pi on a plane P that constitutes a part of the surface of a three-dimensional object and displayed on the display pixel dlK on the display screen S, the plane P at the point pi The pattern information of the point p1 is calculated according to the direction of the point p1. Here, for convenience of explanation, when displaying the three-dimensional object surface P on the display screen S, it is assumed that the observer's viewpoint is placed at the point pO, and the display screen S and the surface P to be displayed are expressed one-dimensionally. The extension of the straight line connecting the display pixel d1 on the display screen S from the point po intersects the plane P at the point p1, and the angle θ between the straight line po-1)l and the normal vector N of the plane P at the point plK Let be the direction of plane P. At this time, in order to calculate the pattern information to be written corresponding to point 1) 1, a second point p2 is found on the surface P according to the inclination angle θ of the surface P with respect to the point pl. The method for finding the point p2 is that the distance between the points pl and p2 increases as the angle θ increases, or the area of the area described by the two points p1 and p2 increases as the t angle θ increases. The position of the point p2 may be set so that the angle θ becomes a function of the angle θ. As a specific example, find a point nl on the normal vector N that is a certain distance away from the intersection p1, and let p2 be the point where the extension of the straight line connecting po and 01 intersects the plane P. p2 is found. When the angle θ is large, the point p2 is located far from the point pl, and when the angle θ is small, the point p2 is located close to the point p1.K
Become. Point p1. Once p2 is determined, coordinate transformation is performed using a predetermined correspondence relationship between another coordinate system (tx, ty) and the defined surface pattern information T as shown in FIG. to find the coordinate values of points Jat and az corresponding to point pl+92 on the coordinate system (tx, ty), and within the area defined by two points al and a2 (two points With al and a2 as vertices, coordinate axis/tx
, ty) is displayed as the value of the display pixel d1 on the display screen S as the pattern information of the object surface at the point p1.

FIG. 3 is a block diagram showing an embodiment of the surface display device of the present invention. In FIG. 3, reference number 1 is a control circuit, 2
1 is a graphic information reading circuit, 3 is a graphic memory, 4 is a display point calculation circuit, 5 is a surface direction calculation circuit, 6 is a display pixel value calculation circuit, 7 is a pattern memory, 8 is an image memory, 9 is a display circuit, 1゜ represents the display.

The operation of the embodiment shown in FIG. 3 will be described below with reference to the reference numerals shown in FIGS. 1 and 2. The graphic information reading circuit 2 receives a surface display processing start signal sent from the control circuit 1 through the signal line 101 and displays the graphic information on the display screen S from among the graphic information stored inside the graphic memory 3. The surface information of the surface P is searched through the signal line 102 to determine the surface to be displayed, and the surface information is outputted to the display point calculation circuit 4 through the signal line 103.

The display point calculating circuit 4 calculates the point pl displayed on the display pixel S on the display from the surface information sent from the graphic information reading circuit 2. The specific processing of the display point calculation circuit 4 includes the plane P obtained through the signal line 103.
A calculation is performed to obtain the coordinates of the intersection of the line and the straight line connecting the display pixel d1 on the display screen S and the viewpoint pO as a point pl.

The obtained intersection point coordinates are output as position information on the plane P displayed on the display pixel d1 of the display to the plane direction calculation circuit 5 through the signal line 104 and to the display pixel value calculation circuit 6 through the signal line 105.

The surface direction calculation circuit 5 calculates the direction of the surface P obtained by the graphic information reading circuit 2 at the intersection point p1 obtained by the display point calculation circuit 4. As a specific means of calculating the direction, the direction of the normal vector N of the surface at the intersection point is determined. intersection p
The determined direction N of the plane in lK is output to the display pixel value calculation circuit 6 through the signal line 106.

The display pixel value calculation circuit 6 calculates the positional coordinate information of the intersection p1 obtained by the display point calculation circuit 4 and the surface direction N at the intersection p1 obtained by the surface direction calculation circuit 5 in advance through a signal line 107. While referring to the surface pattern information T stored in the pattern memory 7, the value of the display pixel d1 of the display corresponding to the position of the intersection p1 is calculated. That is, point pi
A point p2 corresponding to the direction N is determined, and the average value of the surface pattern information T determined corresponding to the point 1)ltp2 is written into the image memory 8 through the table signal line 108.

The pattern memory 7 stores pattern information necessary to calculate the value of each display pixel. Note that the pattern information can be stored in two ways: a case in which all the pattern information is calculated in advance for each display pixel, and a case in which a program necessary to obtain the value of each pixel is set.

In the image memory 8, the value of each display pixel is stored in a position corresponding to each display pixel on the screen display by the above processing.

When the display circuit 9 receives a display start signal from the control unit 1 through a signal line 109, it reads screen data to be displayed on the display screen from the image memory 8 through a signal line 110 and outputs it to the display 10 through a signal line 111 as image information.

The display 10 receives and displays the display pixel values stored in the image memory 8 as image information via the display circuit 9.

(Effects of the Invention) As explained above, the surface display device of Pa-Ni-Haimei can display a three-dimensional object with various patterns and shape changes on the surface as an image on a display screen such as a color CRT without causing discontinuity. There are 7 effect methods that can prevent this and display it in high quality.
be.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing a geometrical arrangement for explaining a surface display method according to an embodiment of the present invention, and FIG. 2 is a conceptual diagram showing a surface pattern information set on the three-dimensional object surface P shown in FIG. 1. A conceptual diagram illustrating the processing, and FIG. 3 is a block diagram of an embodiment of the present invention. l... Control circuit, 2... Graphic information reading circuit, 3...-- Graphic memory, 4...
Display point calculation circuit, 5...plane direction calculation circuit, 6.
...Display pixel value calculation circuit, 7...Pattern memory, 8...Image memory, 9-...
...Display circuit, lO...Display, P...
・・・・Surface, S・・・・Display screen, pO・
·····perspective. S de) sub'shii && half 1 figure 弗

Claims (1)

[Claims] a screen; a surface information means for obtaining information about the surface of a three-dimensional object;
a pattern information means for obtaining surface pattern information to be expressed on the surface; a display point calculation means for obtaining a display point that is a point on the surface displayed in each display pixel on the screen; surface direction calculation means for calculating the direction of the
A surface display device comprising display pixel value calculation means for calculating a value of a pattern displayed on the corresponding display pixel from the surface pattern information according to the direction for each display point.