JPH06266853A - Shading processing method and its device - Google Patents

Abstract

PURPOSE:To execute the real time processing of shading by simple constitution. CONSTITUTION:This shading processor is provided with computing elements 43, 44 for rotating a light beam vector around the normal of a polygon end point so as to align the vector to any one of x, y and z coordinate axes, computing elements 47, 48 for rotating a visual line vector only by a difference between the light beam direction and the visual line direction so as to align the vector to the coordinate axis and a shading computing element 51 for calculating the intensity of diffusely radiated light based upon the rotated light beam vector, calculating the intensity of mirror face reflected light based upon the rotation of the visual line vector and finding out the color values of R, G and B of the polygon based upon the intensity of diffusely radiated light and the intensity of mirror face reflected light to shade a polygon graphic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shading processing method and device for adding a shadow to a three-dimensional image representing a solid to facilitate the understanding of the solid.

[0002]

2. Description of the Related Art Two-dimensional (flat) such as CRT display
When a three-dimensional solid figure is displayed on a display device by perspective conversion processing, perspective processing, and the like, shading processing, that is, shading processing is performed based on a light reflection model in order to give a natural feeling to a displayed object.

As a method of this shading,
Towing Fong (Bui, Tung, Phon)
g) Phong shading and the like are known.

This phong shading is expressed by the following equation 1.
Based on the formula, the light intensity in the line-of-sight direction is calculated based on the vector function shown in FIG.

[0005]

[Equation 1]

Further, as a shading method which ignores specular reflection, the Lambert shown in the following equation 2 is used.
t) There is a shading method.

[0007]

[Equation 2]

When applying this algorithm, it is necessary to calculate the ray vector and the surface normal vector as needed.
Requires large-scale dedicated hardware that operates extremely fast.

An apparatus for realizing the Lambertian shading method with a simple circuit is proposed in Japanese Patent Application Laid-Open No. 2-51789 (International Patent Classification G06F 15/72).

This apparatus first calculates the surface normal of the object,
After that, inverse rotation of the rotation of the object is performed only on the ray vector, and the shadow is added by the above model, so it is not necessary to recalculate the normal vector with the rotation of the object,
It is intended to realize high-speed operation with a simple circuit.

[0011]

However, the above-mentioned device is established only in the relationship between the surface normal of the object and the ray vector as in the Lambert model, and considering the specular reflection as in the Fong model, the line-of-sight vector becomes The reflection vector must also be considered and cannot be applied when expressing a realistic image.

Further, when the light ray vector moves, in order to calculate the unit vector, it is necessary to perform a complicated calculation shown in the following expression (3).

[0013]

[Equation 3]

As shown in the equation (3), this calculation is complicated and it is difficult to speed up the square root. Also,
The same applies to the ray vector.

For this reason, conventionally, there is a problem in that there is a delay in a system capable of transmitting a user's steering wheel operation in real time, such as a game machine, a flight simulator, a drive simulator, etc. for changing the direction of a light ray and the direction of a line of sight in real time. there were.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a method capable of performing real-time shading processing with a simple configuration.

[0017]

According to the present invention, a ray vector is X, Y, Z = 0, 0, 1 by performing X, Y, Z rotations in the ray direction with respect to a polygon normal vector.
Then, the diffuse reflection intensity of each of R, G and B is calculated.
Then, only the difference between the ray vector and the line-of-sight vector is X,
By performing Y and Z rotations, the line-of-sight vector is changed to X,
It is fixed to Y, Z = 0, 0, 1 and the specular reflection intensity of each of R, G, B is calculated.

[0018]

According to the present invention, it is not necessary to calculate the line-of-sight and the ray vector by complicated calculation, and the line-of-sight and the ray can be changed in real time.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a stereoscopic image display device using the shading device of the present invention, and FIG. 2 is a block diagram showing the configuration of the shading device of the present invention.

This device is shown as an example suitable for use in, for example, a game machine such as a racing game or an airplane control simulation. The overall configuration of a stereoscopic image display device using the shading device of the present invention will be described with reference to FIG.

In this embodiment, simulation images under various conditions are given as a plurality of pieces of polygon information to the polygon end point memory 1 as X, Y, Z coordinate values.

The normal vector values (ANX, ANY, ANZ) of each polygon end point are stored in the polygon end point normal vector memory 2. The vector memory 2 further includes the red diffuse reflection coefficient (Rk) of each polygon.
d), a green diffuse reflection coefficient (Gkd), a blue diffuse reflection coefficient (Bkd) and a red specular reflection coefficient (Rks) of each polygon, a green specular reflection coefficient (Gks),
The blue specular reflection coefficient (Bks), the red ambient light value (Rambient), the green ambient light value (Gambient), and the blue ambient light value (Bambient) are stored. These respective data are given to the shading device 4, which is a feature of the present invention.

The CPU represents all three-dimensional objects as an aggregate of a plurality of polygons, reads out end point information indicating each end point of the polygon, and based on the operation content of an operation unit (not shown) configured by handle access or the like. The situation data corresponding to this situation is calculated according to the converted electric signal, and the data is given to the geometric transformation device 3 and the shading device 4, respectively.

The geometrical transformation device 3 reads data from the polygon end point memory 1 while referring to various polygon data according to a command from the CPU, and performs visual field conversion and perspective projection conversion for rotating the values of the end points of the polygon in the direction of the line of sight. The end point coordinates of the polygon are geometrically transformed and the two-dimensional X, Y coordinates (SX, SY) are given to the screen memory 6. Also,
A field-transformed representative value of the center of the polygon, that is, a representative value (Z value) of the distance from the viewpoint of the polygon is determined, and the data is given to the screen memory 6. The shading device 4 processes the normal vector value of the polygon end point read from the vector memory 2 according to the flowcharts shown in FIGS. 4 and 5, calculates the color of the polygon end point, and determines the color of this polygon end point as the polygon end point. It is given to the color memory 5. Details of the shading device 4 will be described later.

The drawing processing device 7 reads the end point information from the screen memory 6 and the color memory 5 with respect to the polygons contained in the processing area divided in the Y direction of the screen screen, and extracts the polygons associated with the scan lines required by the CRT 9. It is drawn on the bitmap and the data is given to the frame memory 8.

Next, the shading device 4 of the present invention will be further described with reference to FIG. Shading device 4
The normal vector value, the diffuse reflection coefficient, the specular reflection coefficient, and the ambient light value are read from the vector memory 2, and the read data are temporarily stored in the memory interface 41. The vector memory 2 is accessed by the address generated by the address generation circuit 42,
The data is read from the memory.

The data stored in the memory interface 41 is first given to the Y rotation calculator 43. This Y
As shown in FIG. 3A, the rotation calculator 43 rotates the normal vector by the angle (LYO) between the ray vector given by the CPU and the Y axis based on the rotation of the object. The angle LYO value of the ray vector from the CPU with respect to the Y axis is given to the register 45.

Subsequently, the data rotationally moved by the Y rotation calculator 43 is given to the X rotation calculator 44. The X rotation calculator 44 rotates the normal vector by the angle (LXO) between the ray vector given from the CPU and the X axis. This C
The ray vector from the PU, the X axis and the angle (LXO) are given to the register 46. Vectors of these arithmetically processed data are moved as shown in FIG.

Then, the data processed by the X rotation calculator 44 is given to the Y rotation calculator 47. The Y-rotation calculator 47 is configured to calculate the light ray vectors LX, LY, LZ = 0,
0, 1, the line of sight of the processing result of the X rotation calculator 44,
Rotation processing is performed by the difference amount (DEYO) of the ray vector. This difference amount is calculated by DEYO = EYO-LYO. This calculation is performed by the CPU and is given to the register 49 by the CPU. The processing result processed by the Y rotation calculator 47 is given to the X rotation calculator 48.

The X rotation calculator 48 performs a rotation process by the difference amount (DEXO) between the line of sight and the ray vector. This difference amount is calculated by DEXO = EXO-LXO. This calculation is performed by the CPU and is given to the register 50 by the CPU.

Then, the processing result of the X rotation calculator 44,
The processing result of the X rotation calculator 48 is the shading calculator 5
Given to 1. The shading computing unit obtains a color value from the processing result of the X rotation computing unit 44 and the processing result of the X rotation computing unit 48 based on the diffuse reflection coefficient of R, G, B, the specular reflection coefficient, and the ambient light value. The calculated color value is output to the memory interface 52.

The color value stored in the memory interface 52 is stored in the area of the polygon end point color memory 5 designated by the address value generated by the address generation circuit 53.

Each of these arithmetic units is controlled by the controller 54, and the controller 54 operates according to the flowcharts shown in FIGS.

Next, the operation of the present invention will be further described with reference to the flow charts of FIGS.

When the shading operation is started, first,
As shown in FIG. 3A, the angles LXO, LYO, LZO between the ray vector and each coordinate axis and the angles EXO, EYO, EZO between the line-of-sight vector and each coordinate axis are input from the CPU, and the registers 45, 46 is input (step S1). Then, subsequently, the differences DEXO and DEYO between the ray vector and the line-of-sight vector are calculated, and the register 49,
They are stored in the registers 50 (step S2).

Next, the R, G, B diffuse reflection coefficients (Rk
d, Gkd, Bkd) and specular reflection coefficient (Rks, Gk
s, Bks) is input (step S3), and further, the normal vector (ANX, ANY, ANZ) of the polygon end point is input (step S4). After the normal vectors are exchanged (step S5), the X rotation calculator 44,
Y rotation calculator 43, polygon end point, normal vector (N
(X, NY, NZ) the ray vector as X, Y, Z = 0.0
LXO rotation processing so that it becomes 01 (step S6), LY
O rotation (step S7) processing is performed. FIG. 3A shows the state before this rotation process and FIG. 3B shows the state after rotation.

According to this process, it has been conventionally necessary to integrate the light source vector with the normal vector.
Since it is fixed at NX, LNY, LNZ = 0, 0, 1,
As shown in step S8, the internal coefficient (INNER) =-
It can be set to NZ, LX = 0, LY = 0, and LZ = -1.

Using this internal coefficient, the shading calculator 1 calculates the diffuse reflection intensity of R, G, B after rotation. That is, each of the diffuse reflection intensities of R, G, and B is IN
NER = -NZ, that is, -NZ is integrated and R, G,
The diffuse reflection intensity of B is calculated (step S9). Subsequently, in the Y rotation calculator 47 and the X rotation calculator 48, as the rotation processing for setting the light ray vectors LX, LY, LZ to 0, 0, 1, rotation processing is performed by the angle of the difference between the light ray vector and the normal vector. Perform (steps S10 and S11). Figure 3
(B) is before this rotation processing, and (c) is after rotation.

By this processing, the above-mentioned INNE is conventionally used.
Although a complicated process of integrating the line-of-sight vector with the result of subtracting the ray vector and the calculated value of R and the normal vector is required, the process is simplified as shown in step S12. That is, ENX, ENY, ENz = 0,
Since it is fixed at 0 and 1, the second internal coefficient (INNER
2) can be calculated by INNER2 = LZ−2 × NZ × INNER.

Using the second internal coefficient, the shading calculator 51 accumulates the second internal coefficient on the specular reflection intensities of R, G, and B after rotation, respectively, and The specular reflection intensity is calculated (step S13).

Subsequently, in step S14, the shading calculator 51 adds the diffuse reflection intensity after rotation, the same specular reflection intensity and the ambient light value to calculate the colors R, G and B, and the R, G thereof. , B data is output to the memory interface 52.

Then, in step S15, R, G, B
The data is written in the color memory 5, and it is determined in step S16 whether or not the processing of all the polygon end points of the polygon is completed. If not, the process returns to step S3 described above and the above operation is repeated. . When the processing is completed, the process proceeds to step S17, and it is determined in step S17 whether or not the processing of all polygons is completed.
If the processing is not completed, the process returns to step S4,
The above operation is repeated. If it is determined in step S17 that the processing has ended, this shading processing ends.

[0044]

As described above, according to the present invention, it is not necessary to calculate the line-of-sight and ray vector by complicated calculation, and the line-of-sight and the ray can be changed in real time.

[Brief description of drawings]

FIG. 1 is a block diagram showing a stereoscopic image display device using a shading device of the present invention.

FIG. 2 is a block diagram showing a shading device of the present invention.

3A and 3B are schematic diagrams showing a relationship between coordinate axes and a line-of-sight vector and a ray vector, FIG. 3A is a state before rotation processing, FIG. 3B is a state in which a ray vector is rotated according to the present invention,
(C) shows a state in which the line-of-sight vector is rotated according to the present invention.

FIG. 4 is a flowchart showing the operation of the present invention.

FIG. 5 is a flowchart showing the operation of the present invention.

FIG. 6 is a schematic diagram showing a relationship between Fong shading vectors.

[Explanation of symbols]

 1 polygon end point memory 2 polygon end point normal vector memory 4 shading device 5 polygon end point color memory 43,47 Y rotation calculator 44,48 X rotation calculator 51 shading calculator

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tatsuya Nakajima 1-3-3 Nakamagome, Ota-ku, Tokyo Stock company Ricoh Co., Ltd. (72) Inventor Yasuhiro Izawa 1-3-6 Nakamagome, Ota-ku, Tokyo Stocks Company Ricoh

Claims (2)

[Claims] 1. A difference amount between a ray direction and a line-of-sight direction after rotating a ray vector with respect to a normal line of a polygon end point so as to match with any of x, y, and z coordinate axes and calculating diffuse reflected light intensity. A shading processing method characterized in that the line-of-sight vector is rotated so as to match the coordinate axis to calculate the specular reflection light intensity, and the polygon figure is shaded. 2. A means for rotating a light ray vector with respect to a normal line of a polygon end point so as to be aligned with any of x, y, and z coordinate axes, and a diffused radiation intensity is calculated based on the rotated light ray vector. Means, means for obtaining the difference between the ray direction and the line-of-sight direction, means for rotating the line-of-sight vector by the calculated difference so as to match the coordinate axis, means for calculating the specular reflection light intensity based on the rotation of the line-of-sight vector, and the diffuse radiation A shading processing apparatus comprising: means for shading a polygon figure based on the light intensity and the specular reflection light intensity.