JP2006195938A - Glare rendering circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make an algorithm into a circuit, by which both problems are solved, i.e., the appropriate display of glare in drawing a dynamic image and a display arithmetic load. <P>SOLUTION: A glare rendering circuit renders a glare phenomenon respectively through the use of: a means for storing the ratio value of a point (glare light emitting source) to environmental light in a register file when a rendering point comes to have not less than a prescribed intensity relative to the environmental light during a process for rendering an object in a view point coordinate system; a means for storing the maximum and minimum values of the distributed x and y coordinate values and a value most close to the view point of a z coordinate value in the register file when the glare generating source exists on the object having the same identifier, through the use of the identifier and detecting existence of light shielding by using hidden surface erasure after rendering the whole objects concerning the values; a means for giving polygons and flare vectors to generate bloom and flare with the coordinate point as a center to the glare light emitting source; and a means for determining glare luminance with the use of a function table, based on a distance from the glare light emitting source and a distance from a flare vector. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a computer graphics video technology, and belongs to a rendering logic circuit technical field for drawing a glare phenomenon generated in an eyeball by reflected light or light emission source having strong luminance.

  Bloom and flare patterns that occur around the light source as a glare phenomenon are caused by the non-uniformity of eyeball cells and the lens arrangement of lenses. As a means for drawing these glare phenomena by computer graphics, many conventional techniques draw a blue or flare pattern in advance as a two-dimensional pattern and map this pattern to a light source. Mapping techniques have been used. In the technique using the texture pattern for the glare image, it is assumed that there is no light blocking object between the glare light source and the viewpoint. However, in real-time drawing, the positional relationship between the light-emitting object and the other object always changes with the movement of the viewpoint, and the light-emitting source is frequently located behind the other object. Since this field-of-view conversion is normally performed at the rendering (pixel drawing) stage separated from the application processor, it is impossible to determine at high speed in the rendering process whether or not the light source is shielded from light on the application side. . If the application side ignores this positional relationship, unconditionally adds a bloom or flare image to the light source, and uses these images together with hidden surface removal from the depth value of the general image, the light source Even if the light is shielded, a part of the bloom or flare is not shielded, or an image in which a part of the glare is shielded is generated. Since glare is generated in the eyeball, in the real world, a phenomenon in which some rays of glare are blocked by an obstacle does not occur. As a result, the image becomes unnatural. On the other hand, in Japanese Patent Application No. 2003-107094, as a means for solving the above problem, a two-dimensional array flag memory corresponding to the image memory is provided separately from the image memory, and the contrast ratio exceeds a predetermined range during rendering. In this case, the flag is set in the two-dimensional flag memory together with hidden surface erasure, and at the same time, when all the renderings are completed, the two-dimensional flag memory is scanned and a bloom or flare is drawn at the detection position. . Although this method solves the problems of the texture-mapping method, a set of flags distributed in a two-dimensional plane is calculated while scanning the two-dimensional flag memory after the first pass, and for each set region. Since the intensity of the bloom and flare is expressed by obtaining the integrated amount of the number of flags, the calculation load becomes heavy, which is not preferable for real-time drawing.

  An object of the present invention is to make an algorithm circuit that solves both the problems of proper display of glare and display calculation load at the time of dynamic video rendering of the above technique. As details of the problem, the present invention does not use a two-dimensional flag memory, and means for improving the calculation load by two digits or more as compared with Japanese Patent Application No. 2003-107094; In this case, the glare generating means for covering a part, and the definition variables (information for determining the shape) of the bloom and flare are simplified, and the circuit scale is reduced to about 1/4. The means of the present invention for solving each of the above problems will be described below.

  In the present invention, it is noted that there are not so many light emitting sources that generate glare in one video scene, and it is not a two-dimensional flag memory used in Japanese Patent Application No. 2003-107094 but a one-dimensional register. Create a file. Here, the register file of the present invention stores (Xmin, Ymin), (Xmax, Ymax), Zmax, ID (object identifier) of the glare source region and the luminance of the light source for each glare source. zmax is the coordinate value closest to the viewpoint of the z value stored in the register file for each source. The ID is used to identify the light source object. When a luminance higher than a predetermined luminance is detected in the rendering process, the ID is registered in the register file and the ID defined for the light source object (already registered at the same coordinate point). If the IDs match, add the brightness with the same ID in the register file, and if the IDs do not match, newly store the coordinate value, ID, and brightness in the register file. To do. An ID is normally defined for an object to be rendered. In the present invention, when the luminance of a rendering point exceeds a certain value, the ID of the object is compared with the ID stored in the register file. Also, regarding the coordinate value of the glare occurrence point stored in the register file, unlike the prior art, the hidden surface is not erased from the z buffer of the image memory in the rendering stage, and z of the same ID already stored in the register file. Compare with the value only, and replace it if it is close to the viewpoint. As described above, since only the register file having the glare generation brightness is stored in the register file, the stored data is less than one hundredth compared with the two-dimensional flag memory.

  When the rendering step is completed, the register file stores the (Xmin, Ymin), (Xmax, Ymax), Zmax, ID indicating the glare occurrence area, and the accumulated luminance in the area. In the present invention, after rendering, a test is performed to determine whether each light emitting area is located in front of or behind the light-shielding object. In the present invention, (Xmax−Xmin) / 2 and (Ymax−Ymin) / 2, which are the emission center points, are calculated from the maximum and minimum coordinate values of X and Y in the register file, and the center point of each axis is calculated. In contrast, the z value stored in the z buffer of the image memory is compared with Zmax in the register file. When the glare generation area is large, a plurality of sampling points are set in the (Xmin, Ymin) and (Xmax, Ymax) areas, and a hidden surface removal test is performed for each sampling point. When sampling points located before and after the light-shielding object are mixed, count the number of sampling points that are front and rear, respectively, and multiply the ratio by the integrated luminance to obtain the light emitting area. Let it be luminance. As a result, in the conventional two-dimensional flag memory, if the resolution is 500 × 500, for example, 250,000 hidden surface removal tests are required in the rendering stage. In the present invention, for example, 32 glare occurrence points are required. In some cases, a 32-point hidden surface removal test is sufficient. In this way, the processing of 3 digits or more can be reduced by the hidden surface removal processing.

  When the hidden surface erasure test is completed, according to the present invention, based on the integrated value of brightness, the blue drawing is performed in a predetermined area centered on the light emission center point, and the flare drawing is performed together with the flare vector and the light emission center point and the flare vector. A predetermined area surrounding the image is defined as a polygon, and the glare brightness is determined while filling the polygon. The polygon surface for bloom drawing is usually given as a quadrangular area. On the other hand, flare vectors and polygon planes are defined using random numbers in a processor generally called a graphics engine. The distribution of random numbers (flare length) and period (number of flares) depend on the luminance of the light emitting area read from the register file. Higher brightness generally results in longer and thicker flares.

  When an object at the glare generation point passes through, for example, a lens or a cut glass, it is necessary to determine the length and number of flares in consideration of not only the integrated luminance but also the material attribute conditions. The graphics engine manages the attributes of the object in advance, reads the coordinate values and brightness of the register file, and refers to the ID of the glare generation area to refer to the glare generation environment conditions (light source shape, filter presence, etc.) Can be recognized. In the glare rendering circuit, when the emission center point and the polygon are given from the graphics ethidine, the polygon coordinates are interpolated and the distance between the interpolation point (rendering point) and the emission center point is obtained for each rendering point.

（Ａ）式において、レンダリング点とグレア発光中心点間の距離をｒ、発光点からレンダリング点とを結ぶ直線方向とフレアベクトルとがなす方向余弦をｃｏｓθとする。ここで本発明では、距離ｒと方向余弦ｃｏｓθのそれぞれを入力アドレスとするＲＡＭを設け、ＲＡＭには距離ｒを変数とする（１）式のＧ（ｒ）と、また方向余弦ｃｏｓθを変数とする（２）式のＳ（ｃｏｓθ）の関数値をテ−ブル化してそれぞれを記憶する。この結果得られた（２）式のＳ（ｃｏｓθ）から（３）式に示す距離ｒと前記ｓｉｎθを乗算器で乗算した後、再び、（３）式のｄをＲＡＭのアドレスとして与えることにより（４）式を得る。さらに（１）式と（４）式を乗算して（５）式を得る。（５）式のＩｐはレンダリング点のグレア輝度となる。ここでＲＡＭテ−ブルは物理的に１つのＲＡＭのアドレスをシェア−して用いることができる。また乗算器も同様である。またｋ_０〜ｋ_２はそれぞれ係数を示す。
本発明では（１）、（２）および（４）式の関数値をＲＡＭに記憶する一方、（３）および（５）式はこのＲＡＭで得られた出力値を乗算器により演算したものである。式（Ａ）はレンダリング点と発生点からの距離ｒが大きくなればなるほど減衰する関数Ｇ（ｒ）と、レンダリング点とフレアラインまでの距離ｄが大きくなればなるほど減衰するＦ（ｄ）との積で表す。（１）式はブル−ムを、また（５）式はフレアラインを描画する場合に用いる。それぞれの係数は輝度のグラデ−ションを調整する。（１）式の指数部−ｋ_１ｒの距離ｒをＲ−ｒ、Ｇ−ｒおよびＢ−ｒに置き換えると、それぞれ３原色に対応したＧ（ｒ）を描画が可能となる。これはハロ−映像を示す。ここでＲ、ＧおよびＢは発光中心点からの任意の距離となる。（１）式から明らかなように、グラフィックスエンジンが与えるポリゴンが４角形であっても、円形の輝度分布となる。またフレアはフレアベクトルラインに沿って線形の輝度分布となる。
一方、（Ａ）式のＧ（ｒ）およびＦ（ｄ）はテ−ブルで生成されているため非線形な任意関数を記憶することができる。例としてＦ（ｄ）を一定値として、Ｇ（ｒ）のみを使用すれば円形のブル−ムを表現することができる。またＧ（ｒ）およびＦ（ｄ）を適当な曲線でテ−ブル化することにより、楕円形状のブル−ム描画が可能となる。以上から本発明では少ないレンダリング情報から多様な形状を表現可能とする。
（Ａ）式における２点間の距離計算や２点が結ぶ直線方向とフレアベクトルとの内積ｃｏｓθはグレア回路内に実装することもできるが、通常、光反射計算回路に含まれており、２点間の距離や内積計算は乗算器、加減算器および平方根回路で構成されるが詳細は本発明の範囲ではない。In the present invention, three of the polygon, the glare emission point coordinate value, and the flare vector are defined as glare generation variables. The distance from the light emitting point to the drawing point (polygon interpolation point or rendering point) is used to determine the bloom or halo, and the flare is determined from the direction cosine formed by the linear direction connecting the two variables and the flare vector. To do. This relationship is shown in equation (A).

In equation (A), the distance between the rendering point and the glare emission center point is r, and the direction cosine formed by the linear direction connecting the light emission point to the rendering point and the flare vector is cos θ. Here, in the present invention, a RAM having the distance r and the direction cosine cos θ as input addresses is provided, and the RAM has G (r) in the equation (1) with the distance r as a variable, and the direction cosine cos θ as a variable. The function value of S (cos θ) in the equation (2) is converted into a table and stored. By multiplying the distance r shown in equation (3) by the sin θ obtained from S (cos θ) in equation (2) and the sin θ obtained as a result of this, and again giving d in equation (3) as the RAM address. (4) Equation is obtained. Further, equation (1) and equation (4) are multiplied to obtain equation (5). Ip in equation (5) is the glare luminance at the rendering point. Here, the RAM table can be used by physically sharing the address of one RAM. The same applies to the multiplier. K _{0 to} k ₂ represent coefficients.
In the present invention, the function values of the expressions (1), (2) and (4) are stored in the RAM, while the expressions (3) and (5) are obtained by calculating the output value obtained by the RAM by a multiplier. is there. Equation (A) is a function G (r) that attenuates as the distance r from the rendering point to the generation point increases, and F (d) that decreases as the distance d from the rendering point to the flare line increases. Expressed as a product. Equation (1) is used for drawing a bloom, and equation (5) is used for drawing a flare line. Each coefficient adjusts the gradient of brightness. If the distance r of the exponent part -k ₁ r in the equation (1) is replaced with Rr, Gr, and Br, G (r) corresponding to the three primary colors can be drawn. This shows a halo-picture. Here, R, G, and B are arbitrary distances from the light emission center point. As is clear from the equation (1), even if the polygon provided by the graphics engine is a quadrangle, a circular luminance distribution is obtained. The flare has a linear luminance distribution along the flare vector line.
On the other hand, since G (r) and F (d) in the formula (A) are generated as a table, a nonlinear arbitrary function can be stored. For example, if F (d) is a constant value and only G (r) is used, a circular bloom can be expressed. Further, by rendering G (r) and F (d) with a suitable curve, it is possible to draw an elliptical bloom. As described above, in the present invention, various shapes can be expressed from a small amount of rendering information.
The distance calculation between the two points in equation (A) and the inner product cos θ between the straight line connecting the two points and the flare vector can be mounted in the glare circuit, but are usually included in the light reflection calculation circuit. The distance between points and the inner product calculation are constituted by a multiplier, an adder / subtracter and a square root circuit, but the details are not within the scope of the present invention.

  As described above, in the present invention, when the luminance of the object exceeds a certain level in the rendering in the viewpoint coordinate system, each of the coordinate value, luminance, and identifier information of the rendering point is provided and stored in the register file. Means and, when storing the information in the register file, compares the identifiers in the register file already stored, and if the identifiers match, means for integrating the information and the luminance in the register file; The register file is provided with a storage area for storing the maximum and minimum values of the x and y coordinates and the z coordinate value closest to the viewpoint, and the z value in the register file is compared with the z value of the rendering point. If the z value of the rendering point is close to the viewpoint, the z value of the register file is replaced with the z value of the rendering point. If the maximum and minimum values of the x and y coordinates of the rendering point are compared with the coordinate values in the register file, and the coordinate value of the rendering point is the maximum or minimum value, the corresponding register file Means for updating the coordinate value of the storage area, means for writing the coordinate value, luminance and identifier of the rendering point in a new storage area of the register file if the identifiers do not match; When the luminance of the register file, the maximum and minimum values of the x and y coordinates are sequentially read out, the z value of the register file is compared with the z value of the z buffer, and the z value of the register file is closer to the viewpoint A method of generating glare proportional to the read luminance intensity with the center point of the area surrounded by the maximum and minimum values as the origin. And each means that does not draw glare if it is far from the z value of the z buffer, means for obtaining an area from the maximum and minimum values of x and y coordinates read from the register file, and the area Means for providing a plurality of sampling points in the region of the maximum / minimum coordinate values when a predetermined size is exceeded and the result of comparison with the z value of the z buffer is far from the z value of the z buffer And a means for comparing the z value of the z buffer for each sampling point and determining the glare intensity from the ratio of the number of sampling points in the front or rear, and the intensity of the luminance read from the register file. As a means for drawing a flare having a proportional size, a flare origin, a flare vector, and a polygon surrounding the flare vector are defined, and the polygon Means for interpolating a polygon from the vertex coordinate values defined in the process to obtain an interpolation point, a distance between the interpolation point and the flare origin, and a direction vector connecting the flare origin and the polygon interpolation point And a RAM for obtaining a direction cosine formed by the flare vector and the flare vector, and a RAM for obtaining a damping function value having the distance and the direction cosine as variables, and a distance between the interpolation point and the flare vector. The function value is stored, the distance and the direction cosine are used as input addresses, the respective function values are read out, and then the flare and the brightness around the flare are determined using a multiplier and an adder / subtractor. Features.

  With the circuit of the present invention, a glare phenomenon such as a night view or a car headlight can be displayed in real time, and the expression of glare can be changed according to the intensity of the light source and environmental conditions.

  The technology of the present invention is implemented in an LSI, a programmable logic circuit or the like or implemented in the form of IP (Intelligent Property), and is applied as a computer graphics video generation processor.

  Examples of the present invention will be described below. FIG. 1 shows a glare generation area storage circuit of the present invention, which is a circuit for storing the glare generation point coordinate value and the luminance. In FIG. 1, a shader 10 indicates the interpolation interpolation point from the information obtained by interpolating the three-dimensional coordinate value, texture coordinate value, normal line, light source incident angle, viewing angle, etc., defined at the polygon vertex. This is a circuit for determining luminance. The luminance Ip at the interpolation point is compared with the ambient light Ie by the luminance comparator 11. The luminance Ip is the sum of diffusion and specular reflection in the case of reflected light, and the light source luminance in the case of a light source. When the difference absolute value Ic between the luminance and the ambient light exceeds a predetermined magnitude, the identifier coincidence detection circuit 12 performs coincidence detection with the IDs of the interpolation point and the IDd stored in the register file 14. When the IDs match, the maximum / minimum calculation circuit 13 receives the already stored maximum / minimum values of the X and Y axes and the maximum value of the Z axis (value closest to the viewpoint) from the register file 14, The magnitudes are compared from the (X, Y, Z) values input from the shader side. If the new coordinate value (X, Y, Z) input from the shader is either maximum or minimum compared to the maximum / minimum value of the register file, the corresponding value is replaced and the register file is updated. . The register with the maximum Z coordinate value is stored in the register file. That is, the maximum / minimum calculation circuit 13 compares the maximum and minimum values of the X and Y coordinates and the maximum value of the Z coordinate from the register file with the coordinate values from the shader input, and replaces the values. A subtractor and multiplexer are implemented. On the other hand, if the IDs do not match, X, Y, Z, ID, and the luminance difference value Ic are newly stored in the register file 14. In this case, the X and Y values are stored as initial values in both the maximum and minimum bit fields. If the register file capacity is 32 words, for example, a glare occurrence area of 32 coordinate points can be stored. One word is composed of the maximum and minimum values of the X and Y coordinates, the maximum Z coordinate value, the identifier and the bit field of the luminance, the range of the X and Y coordinate values is 11 bits, the Z coordinate value is 32 bits, If the identifier is 8 bits and the luminance range is 10 bits, 1 word is 94 bits.

  In the present invention, when the glare generation point is on a polygon having the same identifier, it is handled as one generation source even if it is spread over the area. Therefore, the maximum and minimum values of X and Y are stored in correspondence with a case where a plurality of generation points are distributed and become planar. The size of the glare surface can be determined from the maximum and minimum values. When Ic exceeds a predetermined value, it is compared whether or not IDs given from the shader have been registered in the register file 14. If the same ID has already been registered, the physical address of the register file of the matched ID register is read, this is given to the register file 14, the stored luminance Ir is read, and the difference value between Ip and Ie Ic is added by the adder 15 and the addition value Σ (Ic + Ir) is stored in the register file 14. On the other hand, if the IDs from the shader do not exist in the register file 14, they are newly registered in the ID bit field of the register file, and at the same time, an address for the register file is allocated, and the glare occurrence point coordinate value and the luminance Ic (Ir = 0) is stored in the register file 14 of the allocated address.

  When all the renderings are completed, the maximum and minimum coordinate values of X and Y, the Z maximum value, and the total luminance value stored in the register file 14 are read out. Normally, this reading is performed for each word by a processor called a graphics engine which is responsible for visual field conversion. From the read coordinate values, the sizes of the X and Y regions are checked from the maximum and minimum values. If it is within the predetermined range, access is made at the X and Y center coordinate points read from the register file from the z buffer storing the image data and its Z value normally stored in the drawing process. The value is compared with the maximum z value of the register file (this processing is performed by the graphics engine software, so the circuit is not shown). If the z value of the z buffer is larger, the glare occurrence point is ignored and the next register file information is read. On the other hand, if the z maximum value of the register file is larger than the z value of the z buffer, the X and Y coordinate center points are set as glare occurrence points. For the shape of glare, a polygon consisting of a quadrangle determined from the total value of the luminance is defined, and this is interpolated. That is, if the total luminance value is large, the polygon size is increased. Further, when the luminance exceeds a predetermined magnitude, the flare vector is given to the glare function calculation circuit (FIG. 2). Polygon generation and flare vectors are determined by the graphics engine. The graphics engine creates a polygon size table corresponding to the luminance level, and the flare vector creates a random number distribution value and a periodic value table corresponding to the luminance level in advance. Refer to the bull. The flare vector generates a random number having a glare generation point as an origin from the distribution and the periodic value, and generates a flare vector using a straight line connecting the origin and the random point as a flare line. The graphics engine also generates a polygon surrounding the size of the flare vector (a linear distance connecting the origin and the random number point), and outputs this to the renderer. Reading from the register file 14 ends when all registered IDs are completed.

よって、距離計算回路２０には加減算器、乗算器および平方根回路を実装する。距離ｒおよびｃｏｓθがマルチプレクサ２１で選択された後、これらの値を関数テ−ブル２２のアドレスとして与える。関数テ−ブルはＲＡＭで構成され、前記（Ａ）式による関数値を記憶する。関数テ−ブルから出力する情報は、１例としてFIG. 2 shows a function operation circuit of the glare rendering circuit of the present invention. When the graphics engine determines the glare generation point and the polygon size, it sends the generation point coordinate value, the polygon coordinate value, and the flare vector to the renderer. The rendering circuit interpolates the inside of the polygon from the polygon vertex coordinate values to obtain coordinate values inside all the polygons (the interpolation circuit is a general circuit and is not shown in FIG. 2). In FIG. 2, the distance calculation circuit 20 receives the flare vector F, the glare occurrence point coordinates (X0, Y0, Z0), and the interpolation point (Xr, Yr, Zr). The distance calculation circuit 20 calculates the difference for each coordinate component, adds the squares thereof, and then calculates the distance between the two points, the direction R connecting the glare occurrence point and the interpolation point, and the flare vector F. And an arithmetic circuit for obtaining a direction cosine. This processing is based on equation (B).

Therefore, an adder / subtracter, a multiplier, and a square root circuit are mounted on the distance calculation circuit 20. After the distance r and cos θ are selected by the multiplexer 21, these values are given as the addresses of the function table 22. The function table is composed of a RAM and stores a function value according to the equation (A). The information output from the function table is an example

G (r) and S (cos θ) in the term formula (A). That is, the function table stores equations (1) and (2) of equation (A) with r and cos θ as inputs. S (cos θ) output from the function table by the input cos θ is multiplied by the distance r obtained by the distance calculation circuit 20 and the multiplier 23 through the multiplexer 25, and the expression (3) in the expression (A) is executed. To do. The multiplication result d is further returned to the multiplexer 21 and again given to the function table to output F (d) in the equation (A). This F (d) is temporarily stored in the register 24. Next, r is given to the function table input again to output the expression (1) of the expression (A), and F (d) stored in the register 24 and the function table output G (r) through the multiplexer 25. ) Is multiplied by the multiplier 23 to obtain the expression (5) in the expression (A). As described above, by performing the recursive calculation using each of the function table, register, multiplexer, and multiplier, various information can be processed with a few circuits.

  By mounting the circuit of the present invention as an IP (Intelligent Property) or on a graphics processor LSI chip, real-time drawing can be performed in a system such as video production or CG game.

FIG. 1 “Shows the glare generation area storage circuit of the present invention.”
FIG. 2 "shows a function operation circuit of the present invention."

Explanation of symbols

FIG.
10 Shader
11 luminance comparator 12 identifier coincidence detection circuit 13 maximum / minimum value calculation circuit 14 register file 15 addition circuit diagram 2
20 Distance Calculation Circuit 21 Multiplexer 22 Function Table 23 Multiplier 24 Register 25 Multiplexer

Claims (4)

  When the contrast ratio between the rendering point and the ambient light exceeds a predetermined size, the coordinate value of the rendering point is stored in the glare video rendering circuit by computer graphics. In the means for generating glare as a generation source, a register file is provided for storing information of each of the coordinate value of the rendering point, the luminance, and the identifier of the rendering object, and when storing the information in the register file, the identifier and the register Means for comparing the identifiers already stored in the file, and if the identifiers match, means for storing in the register file a value obtained by adding the luminance of the rendering point and the luminance of the register file; The maximum and minimum coordinate values, and the z coordinate value is the viewpoint When a storage area for storing the closest value is provided, and the xy coordinate value of the rendering point is compared with the maximum / minimum coordinate value in the register file, the coordinate value of the rendering point becomes the maximum or minimum value. The means for updating the corresponding register file storage area is compared with the rendering point and the z value in the register file, and if the z value of the rendering point is close to the viewpoint, the z value of the register file is used as the z value of the rendering point. When the identifier does not match, the means for writing the coordinate value, the luminance and the identifier of the rendering point respectively in a new storage area of the register file, and after the rendering, the xy coordinate of the register file The maximum / minimum values and luminance are read sequentially, and the register area is set to the center point of the surface area surrounded by the maximum / minimum values If the z value of the register file is closer to the viewpoint, the means for generating the glare proportional to the read luminance intensity and the z value of the z buffer are compared. A glare rendering circuit that draws a glare video by each means that does not draw glare when it is far away.   2. The circuit according to claim 1, wherein means for determining a surface area of a glare light source from the maximum and minimum values of xy coordinates stored in the register file, the surface area exceeds a predetermined size, and the z value of the register file As a result of the comparison with the z value of the z buffer, a plurality of sampling points are provided in the surface region, and the z value of the z buffer is set for each sampling point. And a glare rendering circuit comprising means for determining the glare intensity from the ratio of the number of sampling points located at the front and rear.   The circuit according to claim 1, wherein the flare origin, the flare vector, and a polygon surrounding the flare vector are defined and applied to the glare rendering circuit as means for drawing a flare having a size corresponding to the intensity of the luminance read from the register file. In the glare rendering circuit, means for obtaining an interpolation point from the vertex coordinate value of a polygon, a distance between the interpolation point and the flare origin, and a direction vector toward the flare origin and the polygon interpolation point, Means for obtaining each direction cosine formed by the given flare vector, a RAM table, a damping function value having the distance and direction cosine as variables, and a distance between the interpolation point and the flare vector are provided. Each of the function values for obtaining is stored, and the distance and the direction cosine are input addresses, respectively. After reading the function value, glare rendering circuit having respective means for determining the brightness of the surrounding flare and the flare using multiplier and adder-subtracter.   3. The circuit according to claim 1, wherein the flare origin is a center point of a region indicated by the maximum / minimum values of the xy coordinates, and the center point of the region is farther from the z value of the z buffer. Means that a sampling point located in front of a plurality of sampling points defined in the region is set as a flare origin, and the flare vector is a random number having a distribution region and a period corresponding to the magnitude of the luminance. A glare rendering circuit comprising means for determining and a means for referring to the identifier of the register file to determine the length and number of flare vectors according to the object attribute of the glare source in addition to the magnitude of the luminance .

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