JP2006277488A - Program, information storage medium, and image generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a program, an information storage medium, and an image generation system capable of expressing shadows and shadows like a hand-drawn picture.
An original image is generated by drawing an object after perspective transformation, and a shadow color (Rc) corresponding to the original color is based on the original colors (Rw, Gw, Bw) that are the colors of each pixel of the original image. , Gc, Bc), the shadow information of the object is obtained, and the original color and the shadow color corresponding to the original color are combined based on the shadow information.
[Selection] Figure 3

Description

  The present invention relates to a program, an information storage medium, and an image generation system.

  Conventionally, an image generation system (game system) that generates an image viewed from a virtual camera (a given viewpoint) in an object space that is a virtual three-dimensional space is known. Taking an image generation system capable of enjoying a role-playing game (RPG) as an example, a player operates a character (object), which is his or her own character, and moves it on a map in the object space to play against an enemy character. Play games by interacting with other characters or visiting various towns.

  In recent years, non-photorealistic rendering (NPR) that generates hand-drawn images simulating cartoons and paintings such as toon shading has attracted attention, in contrast to photoreal rendering that generates images that pursue virtual reality. Various image generation methods have been developed.

  In such an image generation method, for example, when generating an image of a character or a background, when a shade or shadow is given to an object, the color representing the object is black or the like. It was expressed with a biased color in a specific color direction. The process of determining shades and shadows depends largely on human visual characteristics, especially when trying to create hand-drawn expressions, and conventional methods have found methods that realize color expression based on these characteristics. It was not put out.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a program, an information storage medium, and an image generation system that can express shadows and shadows like a hand-drawn picture.

  The present invention is an image generation system for generating an image in which an object space is viewed from a given viewpoint, a drawing unit that draws an object after perspective transformation to generate an original image, and each of the original images Based on an original color that is a pixel color, a shadow color setting unit that sets a shadow color corresponding to the original color, a shadow information calculation unit that obtains shadow information of the object, the original color, and the original color The present invention relates to an image generation system including a color composition unit that composes the corresponding shadow color based on the shadow information. The present invention also relates to a program that causes a computer to function as each of the above-described units. The present invention also relates to an information storage medium that can be read by a computer, and stores (records) a program that causes the computer to function as each of the above-described units.

  Shading information depends on the brightness of the shaded part that appears in the object itself and the influence of the object, depending on the angle between the light beam from the light source and the object when the object is placed in the object space. This information is obtained based on the brightness of the shadow portion appearing in the object. Accordingly, in this specification, the term “shadow” is used as a term including a shade and a shadow.

  According to the present invention, the shadow color corresponding to the original color (the drawing color of the pixels of the original image) is set. The shadow color is not a monotonous color reduction of the original color but a color set for each color according to the brightness of the original color. In the present invention, based on the shadow information of the object obtained by light source calculation or the like, the original color and the shadow color are combined to generate an image in which the object is shaded like a hand-drawn picture. can do.

  In the image generation system, the program, and the information storage medium according to the present invention, the shadow color setting unit performs a process of multiplying each color component of the RGB color system constituting the original color by a given conversion coefficient to perform the shadow color setting. When a color is set and the conversion coefficient to be multiplied by the R component is Kr, the conversion coefficient to be multiplied by the G component is Kg, and the conversion coefficient to be multiplied by the B component is Kb, the relationship of Kb> Kr> Kg You may have. The shadow color may be obtained based on the shadow color setting method. In this way, in the color components of the RGB color system, the G component that is more sensitive to humans' sensitivity to color brightness is reduced more greatly, as if it was selected based on human sensitivity. A simple shadow color can be set.

  In the image generation system, the program, and the information storage medium of the present invention, the shadow color setting unit further applies given correction coefficients Br, Bg, and B to the values of the respective color components obtained by multiplying the conversion coefficients. The shadow color may be set based on the value of each color component after the power correction by correcting the power to a power of Bb. The shadow color may be obtained based on the shadow color setting method. Even if the shadow color is set according to the brightness of the original color, it is not possible to set an appropriate shadow color for all the original colors, and an unnatural shadow color for a small part of the original colors. It may be set. However, if the correction coefficient is raised to the power of the converted value, the shadow color can be corrected to a natural color according to human visual characteristics even for a color that may be set with an unnatural color. it can.

  In the image generation system, the program, and the information storage medium of the present invention, the shadow color setting unit calculates the value of each color component obtained by multiplying the conversion coefficient and the value of each color component after the power correction, Linear interpolation may be performed based on a given interpolation parameter L set according to the lightness of the original color, and the shadow color may be set based on a value after linear interpolation. The shadow color may be obtained based on the shadow color setting method. In this way, the brighter the original color, the stronger the effect of power correction, and the natural shaded shadow color can be set.

  In the image generation system, program, and information storage medium of the present invention, the shadow color setting unit obtains the interpolation parameter L based on the maximum value and the minimum value of each color component of the RGB color system constituting the original color. You may do it. The shadow color may be obtained based on the shadow color setting method. In this way, the interpolation parameter L whose value changes according to the lightness of the original color can be obtained.

  In the image generation system, the program, and the information storage medium of the present invention, the shadow color setting unit includes a color conversion image including color components obtained by multiplying the conversion coefficient, and color components of pixels of the color conversion image. A color-corrected image made up of color components obtained by correcting the power of may be α-blended using the interpolation parameter L as an α value. The shadow color may be obtained based on the shadow color setting method. In this way, an appropriate shadow color corresponding to the original color can be set by a simple process called α blending.

  In the image generation system, the program, and the information storage medium of the present invention, the color composition unit obtains the original image and a shadow color image in which each pixel of the original image is drawn with the shadow color from the shadow information. Α blending may be performed using the obtained α value. In this way, it is possible to generate an image that expresses a shadow or shadowed object by a shadow color by a simple process called α blending.

  The present invention also relates to an image generation system for generating an image of an object space viewed from a given viewpoint, a texture mapping unit that maps a texture to a perspective-transformed object, and an object to which the texture is mapped A drawing unit that generates an image by drawing the image, the texture mapping unit using an original image of the object generated using a given original color and a shadow color corresponding to the original color The present invention relates to an image generation system that texture-maps the texture generated by subjecting the generated shadow color image of the object to α blending based on the shadow information of the object. The present invention also relates to a program that causes a computer to function as each of the above-described units. The present invention also relates to an information storage medium that can be read by a computer, and stores (records) a program that causes the computer to function as each of the above-described units. According to the present invention, it is possible to generate an image in which an object is shaded like a hand-drawn picture.

  Hereinafter, this embodiment will be described. In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. In addition, all the configurations described in the present embodiment are not necessarily essential configuration requirements of the present invention.

1. Configuration FIG. 1 shows an example of a functional block diagram of an image generation system (game system) of the present embodiment. Note that the image generation system of the present embodiment may have a configuration in which some of the components (each unit) in FIG. 1 are omitted.

  The operation unit 160 is for a player to input operation data of a player object (player character operated by the player), and the function is realized by a lever, a button, a steering, a microphone, a touch panel display, or a casing. it can. The storage unit 170 serves as a work area for the processing unit 100, the communication unit 196, and the like, and its function can be realized by a RAM (VRAM) or the like.

  The information storage medium 180 (computer-readable medium) stores programs, data, and the like, and functions as an optical disk (CD, DVD), magneto-optical disk (MO), magnetic disk, hard disk, and magnetic tape. Alternatively, it can be realized by a memory (ROM). The processing unit 100 performs various processes of the present embodiment based on a program (data) stored in the information storage medium 180. That is, the information storage medium 180 stores a program for causing a computer to function as each unit of the present embodiment (a program for causing a computer to execute processing of each unit).

  The display unit 190 outputs an image generated according to the present embodiment, and its function can be realized by a CRT, LCD, touch panel display, HMD (head mounted display), or the like. The sound output unit 192 outputs the sound generated by the present embodiment, and its function can be realized by a speaker, headphones, or the like.

  The portable information storage device 194 stores player personal data, game save data, and the like. Examples of the portable information storage device 194 include a memory card and a portable game device. The communication unit 196 performs various controls for communicating with the outside (for example, a host device or other image generation system), and functions thereof are hardware such as various processors or communication ASICs, programs, and the like. It can be realized by.

  Note that a program (data) for causing a computer to function as each unit of this embodiment is distributed from the information storage medium of the host device (server) to the information storage medium 180 (storage unit 170) via the network and communication unit 196. May be. Use of the information storage medium of such a host device (server) can also be included in the scope of the present invention.

  The processing unit 100 (processor) performs processing such as game processing, image generation processing, or sound generation processing based on operation data and programs from the operation unit 160. Here, as the game process, a process for starting a game when a game start condition is satisfied, a process for advancing the game, a process for placing an object such as a character or a map, a process for displaying an object, and a game result are calculated. There is a process or a process of ending a game when a game end condition is satisfied. The processing unit 100 performs various processes using the main storage unit 172 in the storage unit 170 as a work area. The functions of the processing unit 100 can be realized by hardware such as various processors (CPU, DSP, etc.), ASIC (gate array, etc.), and programs.

  The processing unit 100 includes an object space setting unit 110, a movement / motion processing unit 112, a virtual camera control unit 114, an image generation unit 120, and a sound generation unit 130. Note that some of these may be omitted.

  The object space setting unit 110 includes various objects (primitive surfaces such as polygons, free-form surfaces, and subdivision surfaces) representing display objects such as characters, buildings, stadiums, cars, trees, columns, walls, and maps (terrain). A part object or a model object composed of a plurality of part objects) is set in the object space. In other words, the position and rotation angle of the object in the world coordinate system (synonymous with direction and direction) are determined, and the rotation angle (rotation angle around the X, Y, and Z axes) is determined at that position (X, Y, Z). Arrange objects.

  The movement / motion processing unit 112 performs a movement / motion calculation (movement / motion simulation) of an object (such as a character, a car, or an airplane). That is, based on operation data input by the player through the operation unit 160, a program (movement / motion algorithm), various data (motion data), or the like, the object is moved in the object space, or the object is moved (motion, animation). ) Is performed. Specifically, a simulation process for sequentially obtaining object movement information (position, rotation angle, speed, or acceleration) and motion information (position or rotation angle of each part object) every frame (1/60 second). I do. A frame is a unit of time for performing object movement / motion processing (simulation processing) and image generation processing.

  The virtual camera control unit 114 performs a virtual camera (viewpoint) control process for generating an image viewed from a given (arbitrary) viewpoint in the object space. Specifically, a process for controlling the position (X, Y, Z) or the rotation angle (rotation angle about the X, Y, Z axes) of the virtual camera (process for controlling the viewpoint position and the line-of-sight direction) is performed.

  For example, when an object (eg, character, ball, car) is photographed from behind using a virtual camera, the position or rotation angle of the virtual camera (the direction of the virtual camera is set so that the virtual camera follows changes in the position or rotation of the object. ) To control. In this case, the virtual camera can be controlled based on information such as the position, rotation angle, or speed of the object obtained by the movement / motion processing unit 112. Alternatively, the virtual camera may be controlled to rotate at a predetermined rotation angle or to move along a predetermined movement path. In this case, the virtual camera is controlled based on the virtual camera data for specifying the position (movement path) or rotation angle of the virtual camera. When there are a plurality of virtual cameras (viewpoints), the above control process is performed for each virtual camera.

  The image generation unit 120 performs drawing processing based on the results of various processes (game processing) performed by the processing unit 100, thereby generating an image and outputting the image to the display unit 190. When generating a so-called three-dimensional game image, first, geometric processing such as coordinate transformation (world coordinate transformation, camera coordinate transformation), clipping processing, perspective transformation, or light source calculation is performed, and based on the processing result, Drawing data (position coordinates of object vertices, texture coordinates, color data, normal vector, α value, etc.) is created. The drawing data is stored in the main storage unit 172. Then, based on the drawing data (object data), an object (one or a plurality of primitive surfaces) after perspective transformation (after geometry processing) is drawn into a drawing buffer 174 (a frame buffer, a work buffer (intermediate buffer), etc.) Draw in a buffer (VRAM) that can store information. Thereby, an image that can be seen from the virtual camera (given viewpoint) in the object space is generated. When there are a plurality of virtual cameras (viewpoints), an image that can be seen from each virtual camera is generated as a divided image so that it can be displayed on one screen.

  The image generation unit 120 includes a vertex shader 120VS and a pixel shader 120PS.

  The vertex shader 120VS receives a vertex list including vertex data (vertex position coordinates, texture coordinates, color data, normal vector, α value, etc.) of each vertex of the object, and vertex data included in the input vertex list Based on this, vertex shading (vertex processing in a broad sense) is performed. When performing vertex shading, vertex generation processing (tessellation, curved surface division, polygon division) for subdividing a polygon may be performed as necessary. In vertex shading, according to a vertex shader program (first shader program in a broad sense), vertex movement processing, coordinate conversion (world coordinate conversion, camera coordinate conversion), clipping processing, or geometric processing such as perspective conversion are performed. Based on the processing result, the vertex data given to the vertex group constituting the object is changed (updated or adjusted). Then, rasterization (scan conversion) is performed based on the vertex data after the vertex shading.

  The pixel shader 120PS performs pixel shading (pixel processing and fragment processing in a broad sense) that draws pixels (fragments that configure a screen) that configure an image. In pixel shading, according to the pixel shader program (second shader program), texture reading (texture mapping), setting / changing of color data (luminance value, α value), α blending (translucent composition), anti-aliasing, etc. Processing is performed to determine the pixel drawing color of the final display image, and the drawing color of the perspective-converted object is stored in pixel units such as the drawing buffer 174 (frame buffer or work buffer (intermediate buffer)). Output (drawing) to a VRAM. That is, in pixel shading, processing for setting or changing image information (color, normal, luminance, α value, etc.) is performed in units of pixels.

  The pixel shader 120PS includes a shadow information calculation unit 121, a shadow color setting unit 123, a color synthesis unit 125, and a drawing unit 127.

  The shadow information calculation unit 121 performs a process of calculating the shadow information for each drawing pixel of the object based on the shadow information for each vertex obtained as a result of the light source calculation performed by the vertex shader 120VS. Specifically, shade information in units of pixels can be obtained by performing linear interpolation processing on luminance information (color information in a broad sense) and normal vector information based on scanning line information.

  The shadow color setting unit 123 performs a process of setting a shadow color corresponding to the original color based on the original color (the color of each pixel of the original image). Specifically, the color information (luminance information) for the RGB components constituting the original color is multiplied by a given conversion coefficient to obtain the color information (luminance information) for the RGB components constituting the shadow color. Perform the requested process. The conversion coefficient is for each color component of the R component (first color component in a broad sense), G component (second color component in a broad sense), and B component (third color component in a broad sense). Thus, specific coefficients Kr, Kg, and Kb can be given. Further, when setting the shadow color, power correction may be performed by further raising a given correction coefficient to the RGB component value multiplied by the conversion coefficient. As the correction coefficient, specific coefficients Br, Bg, and Bb can be given to the respective color components of the R component, the G component, and the B component. Further, color information of the RGB components constituting the shadow color is obtained by linearly interpolating the RGB component value multiplied by the conversion coefficient and the RGB component value after the power correction based on a given interpolation parameter L. May be requested. Linear interpolation can be realized by α blending using the interpolation parameter L as an α value. The interpolation parameter L can be set to a value corresponding to the lightness of the original color, for example.

  The color synthesis unit 125 uses the α blending function of the pixel shader 120PS to synthesize the original image and a shadow color image obtained by drawing each pixel of the original image with a shadow color based on the shadow information. That is, the color composition unit 125 uses the α value obtained from the shadow information, and combines the original color that is the color of the pixel of the original image and the shadow color that is the color of the pixel of the shadow color image in units of pixels. Perform synthesis processing. Note that the concept of “combining colors” here includes replacing a drawing pixel corresponding to a shadow portion of an object in an original image with a shadow color corresponding to the original color. That is, when the original color and the shadow color are combined based on the α value, the term “composite” is used even if the application rate of one color to the drawing pixel is 0%.

  Note that α blending is a translucent composition process (usually α blending, addition α blending, subtraction α blending, or the like) based on an α value (A value). For example, in the case of normal α blending, the following processes (1) to (3) are performed.

R _Q = (1−α) * R ₁ + α * R ₂ (1)
G _Q = (1−α) * G ₁ + α * G ₂ (2)
B _Q = (1−α) * B ₁ + α * B ₂ (3)
In addition, in the case of addition α blending, the following expressions (4) to (6) are performed.

R _Q = R ₁ + α * R ₂ (4)
G _Q = G ₁ + α * G ₂ (5)
B _Q = B ₁ + α * B ₂ (6)
In the case of subtractive α blending, the processing of the following equations (7) to (9) is performed.

R _Q = R ₁ −α * R ₂ (7)
G _Q = G ₁ −α * G ₂ (8)
B _Q = B ₁ −α * B ₂ (9)
Here, R ₁ , G ₁ , B ₁ are RGB components of an image (original image) already drawn in the drawing buffer 174, and R ₂ , G ₂ , B ₂ should be drawn in the drawing buffer 174. It is an RGB component of an image (shadow color image). R _Q , G _Q , and B _Q are RGB components of an image obtained by α blending. The α value is information that can be stored in association with each pixel (texel, dot), for example, plus alpha information other than color information. The α value can be used as mask information, translucency (equivalent to transparency and opacity), bump information, and the like.

  The drawing unit 127 performs an object drawing process. Specifically, based on drawing data (primitive surface data) created by geometry processing, an object (one or a plurality of primitive surfaces) after perspective transformation (after screen coordinate transformation) is drawn into a drawing buffer 174 (frame buffer, work piece). Draw in a buffer (intermediate buffer). Thus, an image that can be seen from the virtual camera in the object space is generated. The drawing unit 126 draws an original image in which a normal texture is mapped to an object in a frame buffer.

  The sound generation unit 130 performs sound processing based on the results of various processes performed by the processing unit 100, generates game sounds such as BGM, sound effects, or sounds, and outputs the game sounds to the sound output unit 192.

  Note that the image generation system of the present embodiment may be a system dedicated to the single player mode in which only one player can play, or may be a system having a multiplayer mode in which a plurality of players can play. Further, when a plurality of players play, game images and game sounds to be provided to the plurality of players may be generated using one terminal, or connected via a network (transmission line, communication line) or the like. Alternatively, it may be generated by distributed processing using a plurality of terminals (game machine, mobile phone).

  FIG. 2 shows a modification of the functional block of the image generation system of this embodiment. The function block of FIG. 1 is suitable for a method of calculating shadow information of an object and setting a shadow color in real time (every frame update). However, in the system shown in FIG. An image is generated by texture-mapping a texture created by combining an image and an image created with a shadow color corresponding to the original color based on the shadow information of the object onto a perspective-transformed object. The texture obtained by combining the image created with the original color and the image created with the shadow color is stored in the texture storage unit 176. The image generation system shown in FIG. 2 is suitable, for example, when a texture to be mapped to a background object is created in advance when creating a background image with a fixed light source position. Note that it may be applied to a texture mapped to a character object. The main differences from the functional block shown in FIG. 1 will be described below. Specifically, the function of the image generation unit 120 will be described. The drawing unit 127 has the same function as that of the image generation system shown in FIG.

  In the image generation system illustrated in FIG. 2, the image generation unit 120 includes a geometry processing unit 122, a texture mapping unit 124, and a drawing unit 127. That is, the geometry processing unit 122 perspective-transforms the object into the screen coordinate system, and the texture mapping unit 124 maps a given texture to the perspective-transformed object. The drawing unit 127 draws an image of the object to which the texture is mapped in the drawing buffer 174.

  The geometry processing unit 122 performs geometry processing on the object. More specifically, geometric processing such as coordinate transformation, clipping processing, perspective transformation, or light source calculation is performed. Then, the object data (position coordinates of the vertex of the object, texture coordinates, color data, normal vector, α value, etc.) after the geometry processing (after perspective transformation) is stored in the main storage unit 172 of the storage unit 170. .

  The texture mapping unit 124 performs processing for mapping the texture (texel value) stored in the texture storage unit 176 to the object. Specifically, the texture (surface properties such as color and α value) is read from the texture storage unit 176 using texture coordinates or the like set (given) to the vertex of the object. Then, a texture that is a two-dimensional image is mapped to an object. In this case, processing for associating pixels and texels, bilinear interpolation (texel interpolation), and the like are performed. In the image generation system shown in FIG. 2, the texture storage unit 176 stores a texture for expressing an object subjected to shading or shadowing using the original color and a shadow color corresponding to the original color. .

2. Next, the method of this embodiment will be described with reference to the drawings.

2.1 Color Composition Method Using Shadow Color In this embodiment, the shadow color set for each pixel drawing color of the original image is used to determine the pixel drawing color of the original image and the shadow color corresponding to that color. A color composition method is employed to synthesize the image based on the shadow information of the object. Hereinafter, this will be specifically described with reference to FIG.

  First, an image in which a texture with only a pattern is mapped to an object is created as an original image. “Pattern only” means that no shading or shadowing is performed. The color of each pixel of this original image is the original color. Further, a shadow image in which the shadow information obtained as a result of light source calculation for the object is set as an α value is created on the α plane of the original image. The original image and the shadow image can be drawn in the frame buffer. If necessary, it may be drawn in the work buffer. This shaded image is a grayscale image in which the α value is set so that the brighter the result of light source calculation, the higher the value (closer to 1) and the darker the value (closer to 0). Since the shadow information is a parameter that determines the application rate of the original color and the shadow color, as an extreme example, it may be binarized, and a shadow part (α = 0), a non-shadow part (α = 1). In this case, a final image is created by a process of replacing pixels drawn with the original color and pixels drawn with the shadow color.

  Next, in order to create a shadow color image from the original image, a copy image of the original image is created. The copy image can be drawn in a work buffer different from the frame buffer. Then, a shadow color corresponding to the color of the drawing pixel of the copy image of the original image is obtained to create a shadow color image. The shadow color image may be drawn over a work buffer in which a copy image of the original image is drawn, or may be drawn in another work buffer.

  Next, referring to the shadow information of the shadow image drawn on the α plane of the original image, the original image and the shadow color image are synthesized in units of pixels by α blending. An image drawn with a composite color with the shadow color can be generated. Specifically, assuming that the color information of the original image is (Rw, Gw, Bw) and the color information of the shadow color image is (Rc, Gc, Bc), the color information (Rn) of the finally obtained object image , Gn, Bn) are determined by the following formulas (A1) to (A3).

Rn = Rw * α + Rc * (1-α) (A1)
Gn = Gw * α + Gc * (1−α) (A2)
Bn = Bw * α + Bc * (1−α) (A3)
When shadow expression is performed according to the conventional concept, the process simply multiplies the color of the original image (original color) and the color of the shadow image (grayscale color). Instead, the overall color becomes dark and dark. However, according to the color composition method of the present embodiment, the original color is not monotonously reduced, and shadow expression using a shadow color set for each color according to the brightness of the original color is possible. Then, according to the color composition method of the present embodiment, based on the shadow information of the object obtained by light source calculation or the like, the original color and the shadow color are synthesized by using α blending of the original image and the shadow color image. With this simple process, it is possible to generate an image in which the object is shaded like a hand-drawn picture.

2.2 Shadow Color Setting Method In this embodiment, a shadow color setting method for determining the shadow color (Rc, Gc, Bc) from the color of the drawing pixel of the original image (original color (Rw, Gw, Bw)) is adopted. To do.

  Specifically, as shown in FIG. 4, a shadow color can be set by performing a process of multiplying each color component of the RGB color system constituting the original color by a given conversion coefficient Kr, Kg, Kb. . That is, the color conversion image (R1, G1, B1) is created based on the copy image (Rw, Gw, Bw) of the original image drawn in the first work buffer. This color-converted image can be drawn in a buffer (second work buffer) different from the copy image of the original image. In this case, the conversion coefficient multiplied by the R component (Rw) of the original color is Kr, the conversion coefficient multiplied by the G component (Gw) of the original color is Kg, and the conversion is multiplied by the B component (Bw) of the original color. Assuming that the coefficient is Kb, color information (luminance information) about the RGB components of the pixels of the original image is multiplied by a conversion coefficient having a relationship of Kb> Kr> Kg. For example, if the coefficients multiplied by the respective components in the conversion formula when converting the RGB components to gray scale are Gr (˜0.299), Gg (˜0.587), and Gb (˜0.114), Based on the coefficients Gr, Gg, and Gb, conversion coefficients Kr, Kg, and Kb can be obtained. Specifically, Kr = 1−Gr (˜0.701), Kg = 1−Gg (˜0.413), and Kb = 1−Gb (˜0.886).

  The reason for determining the degree of color reduction of each color component in accordance with the ratio of the coefficient multiplied to each color component at the time of gray scale conversion is as follows.

  First, in hand-drawn paintings, for example, when the original color is white, the shadow represented in that part is often expressed in a reddish or bluish color instead of black or gray. When the original color is a skin color, the shadow color is often expressed as a reddish color rather than a color obtained by simply reducing the skin color in the black direction. This is because, for example, the shadow color when the object is near the wall receives the light reflected by the wall, and the reflected light is affected by the red color of the wall color, for example, a red wall. It is thought that it is close to the phenomenon in the real world that the shadow of the received color can be seen. For example, for an object on a desk, a shadow color affected by the color of the desk should be visible. In this way, the color expression of the shadow largely depends on the sensibility of the author, that is, the visual characteristics of the human being.Therefore, in the handwritten painting, the inventors of the present invention have a law in the color expression of the shadow depending on the style of the author. I thought about it. In the gray scale image, the brightness of the gray scale conversion color is set according to the brightness of the original color. Human visual characteristics are generally more sensitive to changes in brightness than to changes in color. From these facts, the inventors of the present invention have the G component that most influences the brightness of the original color in each color component of the RGB color system, and the brightness of the original color in order of the R component and the B component. We thought that there was little contribution. If each color component of the RGB components of the original color is reduced according to the value of the gray scale conversion coefficient, it is possible to set a color that a human will actually select as a shadow color corresponding to the original color. I considered it. That is, when reducing the original color (decreasing luminance), the color component that has little influence on the brightness of the color has a low influence when determining the shadow color in human sensitivity. Therefore, as in this method, by setting the conversion coefficients Kr, Kg, and Kb multiplied by the respective color components of the original color so as to have a relationship of Kb> Kr> Kg, the G component of the original color is most reduced. , G component, R component, and B component are reduced in the order of color reduction, an appropriate shadow color can be set, and the texture of the image can be drastically improved.

  However, if the shadow color corresponding to the original color is uniformly determined according to the influence of the brightness of each color component of the RGB color system as described above, an appropriate shadow is obtained for some of the original colors. It may not be a color. Therefore, color correction may be performed so that the lighter the shadow color, the larger the correction amount. Specifically, as shown in FIG. 4, given correction coefficients Br, Bg, Bb are further added to the RGB color component values (R1, G1, B1) multiplied by the conversion coefficients Kr, Kg, Kb. Power correction that raises to a power may be performed. That is, the color correction image (R2, G2, B2) is created based on the color conversion image (R1, G1, B1) drawn in the second work buffer. This color correction image can be drawn in a different buffer (first work buffer) from the color conversion image. In this way, the shadow color can be corrected to a natural hue according to human visual characteristics even for a color that may be set with an unnatural color. When power correction is performed, for example, Br, Bg, and Bb are set so that the R component value (R1) and the B component value (B1) are corrected to be larger than the G component value (G1). can do.

  Further, when setting the shadow color, as shown in FIG. 4, the values (R1, G1, B1) of the respective color components obtained by multiplying the conversion coefficients Kr, Kg, Kb, and the respective color components after the power correction. (R2, G2, B2) and linear interpolation (for example, α blending) based on a given interpolation parameter L set according to the lightness of the original color (drawing color of each pixel constituting the original image) ). In this case, the shadow color is set based on the values (Rc, Gc, Bc) after linear interpolation. The interpolation parameter L is obtained based on the maximum value and the minimum value of each color component constituting the color of each pixel constituting the original image. For example, if a process of converting RGB color system color components into HLS color system color components is performed, the L component (brightness) of the HLS color system can be calculated as the interpolation parameter L. The image in which the interpolation parameter L is set (interpolation parameter setting image) can be drawn on the α plane of the color correction image (the α plane of the first work buffer). That is, by obtaining the brightness of the original image from the average of the brightest and darkest colors of each pixel of the original image, and changing the application rate of the power correction according to the brightness according to the color of the original image, Shadow colors (Rc, Gc, Bc) can be obtained by an α synthesis process (linear interpolation process in a broad sense) as shown in FIG. Specifically, the color information (Rc, Bc, Gc) of the shadow color is obtained by the following formulas (B1) to (B3).

Rc = R1 * (1-L) + R2 * L (B1)
Gc = G1 * (1-L) + G2 * L (B2)
Bc = B1 * (1-L) + B2 * L (B3)
In this way, the brighter the original color, the stronger the power correction effect can be made, and an appropriate shadow color corresponding to the original color can be set by a simple process called α blending. The interpolation parameter L can also be obtained from luminance information obtained by performing gray scale conversion on the original image and performing gray scale conversion on the original color.

3. Processing of this embodiment Next, a detailed processing example of this embodiment will be described with reference to the flowcharts of FIGS.

  As shown in FIG. 5, it is first determined whether or not it is a frame update (1/60 second) update timing (step S10). If it is the frame update timing (YES in step S10), a game calculation process is performed (step S11). That is, an object arrangement setting process, an object movement / motion process, a virtual camera control process, and the like are performed in accordance with an operation input from the player.

  Next, the shader program for the vertex shader and the pixel shader is transferred, and various parameters necessary for executing the rendering process by executing the shader program are set and transferred (steps S12 and S13). Then, the vertex list of the object is transferred to the vertex shader (step S14), and the vertex shader program and the pixel shader program transferred in step S13 are sequentially executed (steps S15 and S16).

  In the vertex shader and the pixel shader, the shader program is executed according to the flowchart of FIG. First, an original image is generated by drawing an object in the frame buffer (step S20). Next, a shadow image is drawn on the α plane of the frame buffer using the shadow information of the object as an α value (step S21). At this time, the α value is set based on the shadow information of the object so that the brighter part approaches 0 and the darker part approaches 1. Next, the original image of the frame buffer is copied to the first work buffer (step S22). Based on the copied original image, a shadow color image is created as shown in FIG.

  First, the original image copied to the first work buffer is converted into a color-converted image and drawn in the second work buffer (step S23). That is, the luminance value of each color component of the pixel of the original image is multiplied by the conversion coefficients Kr, Kg, and Kb to obtain the luminance value of the color component of the pixel of the color converted image. Next, the interpolation parameter L is obtained from the color of the original image copied to the first work buffer, and is substituted into the α plane of the first work buffer (step S24). That is, the brightness of the original image can be calculated based on the maximum and minimum luminance values of the RGB components of all pixels of the original image, and this brightness can be used as the interpolation parameter L. Next, a color corrected image obtained by performing power correction on the color converted image in the second work buffer is drawn in the first work buffer (step S25). Then, the color conversion image of the second work buffer and the color correction image of the first work buffer are subjected to α composition (α blending) with reference to the α plane of the first work buffer, and the combined shadow color The image is drawn in the second work buffer (step S26).

  Finally, the original image of the frame buffer and the shadow color image of the second work buffer are subjected to α synthesis (α blending) with reference to the α plane of the frame buffer (step S27). That is, the original image and the shadow color image are combined using the shadow information of the object as a combining ratio.

4). Hardware Configuration FIG. 7 shows an example of a hardware configuration capable of realizing this embodiment. The main processor 900 operates based on a program stored in a DVD 982 (information storage medium, which may be a CD), a program downloaded via the communication interface 990, a program stored in the ROM 950, or the like. Perform processing, sound processing, etc. The coprocessor 902 assists the processing of the main processor 900, and executes matrix operation (vector operation) at high speed. For example, when a matrix calculation process is required for a physical simulation for moving or moving an object, a program operating on the main processor 900 instructs (requests) the process to the coprocessor 902.

  The geometry processor 904 performs geometry processing such as coordinate conversion, perspective conversion, light source calculation, and curved surface generation based on an instruction from a program operating on the main processor 900, and executes matrix calculation at high speed. The data decompression processor 906 performs decoding processing of the compressed image data and sound data and accelerates the decoding processing of the main processor 900. Thereby, a moving image compressed by the MPEG method or the like can be displayed on the opening screen or the game screen.

  The drawing processor 910 executes drawing (rendering) processing of an object composed of primitive surfaces such as polygons and curved surfaces. When drawing an object, the main processor 900 uses the DMA controller 970 to pass the drawing data (vertex data and other parameters) to the drawing processor 910 and, if necessary, the texture to the texture storage unit 924. Forward. Then, the drawing processor 910 draws the object in the frame buffer 922 while performing hidden surface removal using a Z buffer or the like based on the drawing data and texture. The drawing processor 910 also performs α blending (translucent processing), depth cueing, mip mapping, fog processing, bilinear filtering, trilinear filtering, anti-aliasing, shading processing, and the like. Programmable shaders such as a vertex shader and a pixel shader are also mounted on the drawing processor 910. According to the shader program that realizes the method of this embodiment, the creation / change (update) of vertex data and the drawing color of pixels (or fragments) are changed. Make a decision. When an image for one frame is written in the frame buffer 922, the image is displayed on the display 912.

  The sound processor 930 includes a multi-channel ADPCM sound source and the like, generates game sounds such as BGM, sound effects, and sounds, and outputs them through the speaker 932. Data from the game controller 942 and the memory card 944 is input via the serial interface 940.

  The ROM 950 stores system programs and the like. In the case of an arcade game system, the ROM 950 functions as an information storage medium, and various programs are stored in the ROM 950. A hard disk may be used instead of the ROM 950. The RAM 960 is a work area for various processors. The DMA controller 970 controls DMA transfer between the processor and the memory. The DVD drive 980 (may be a CD drive) accesses a DVD 982 (may be a CD) in which programs, image data, sound data, and the like are stored. The communication interface 990 performs data transfer with the outside via a network (communication line, high-speed serial bus).

  The processing of each unit (each unit) in this embodiment may be realized entirely by hardware, or may be realized by a program stored in an information storage medium or a program distributed via a communication interface. Also good. Alternatively, it may be realized by both hardware and a program.

  When the processing of each part of this embodiment is realized by both hardware and a program, a program for causing the hardware (computer) to function as each part of this embodiment is stored in the information storage medium. More specifically, the program instructs the processors 902, 904, 906, 910, and 930, which are hardware, and passes data if necessary. Each processor 902, 904, 906, 910, 930 realizes the processing of each unit of the present invention based on the instruction and the passed data.

  The present invention is not limited to that described in the above embodiment, and various modifications can be made. For example, terms (original color, R component, G component, B component, etc.) cited as broad or synonymous terms in the description or drawings (original pixel color, first color component, first color component, The second color component, the third color component, etc.) can be replaced with terms having a broad meaning or the same meaning in other descriptions in the specification or the drawings. Further, the color composition method, the shadow color setting method, and the like are not limited to those described in the present embodiment, and methods equivalent to these methods are also included in the scope of the present invention.

  In the present embodiment, the case where a shadow is applied to an object has been described as an example. However, the present invention is not limited to this, and for example, the object can also be used for highlight expression. In this case, highlight information (specular reflection information) is obtained instead of shadow information, and a specular reflection color (specular. (Rw, Gw, Bw)) is obtained from the original color (Rc, Gc, Bc). it can. That is, it is possible to obtain a specular reflection color brighter than the original color using the shadow color described above as the original color.

  The present invention can also be applied to various games (such as fighting games, shooting games, robot fighting games, sports games, competitive games, role playing games, music playing games, dance games, etc.). Further, the present invention is applied to various image generation systems such as a business game system, a home game system, a large attraction system in which a large number of players participate, a simulator, a multimedia terminal, a system board for generating a game image, and a mobile phone. it can.

The functional block diagram of the image generation system of this embodiment. The functional block diagram of the modification of the image generation system of this embodiment. Explanatory drawing of the method of this embodiment. Explanatory drawing of the method of this embodiment. The flowchart which shows the specific process example of this embodiment. The flowchart which shows the specific process example of this embodiment. An example of a hardware configuration.

Explanation of symbols

100 processing unit,
110 Object space setting unit, 112 Movement / motion processing unit,
114 virtual camera control unit,
120 image generator, 120VS vertex shader, 120PS pixel shader,
121 shadow information calculation unit, 123 shadow color setting unit, 125 color composition unit,
122 geometry processing unit, 124 texture mapping unit, 127 drawing unit,
130 sound generation unit, 160 operation unit,
170 storage unit, 172 main storage unit, 174 drawing buffer,
176 texture storage unit, 180 information storage medium, 194 portable information storage device,
190 Display unit, 192 Sound output unit, 196 Communication unit

Claims (15)

A program for generating an image of an object space viewed from a given viewpoint,
A drawing unit for drawing an object after perspective transformation to generate an original image;
A shadow color setting unit that sets a shadow color corresponding to the original color based on the original color that is the color of each pixel of the original image;
A shadow information calculation unit for obtaining shadow information of the object;
As a color synthesis unit that synthesizes the original color and the shadow color corresponding to the original color based on the shadow information,
A program characterized by causing a computer to function. In claim 1,
The shadow color setting unit is
The shadow color is set by performing a process of multiplying each color component of the RGB color system constituting the original color by a given conversion coefficient,
The relationship is Kb>Kr> Kg, where Kr is the transform coefficient multiplied by the R component, Kg is the transform coefficient multiplied by the G component, and Kb is the transform coefficient multiplied by the B component. Program. In claim 2,
The shadow color setting unit is
The value of each color component obtained by multiplying the conversion coefficient is further subjected to power correction by raising a given correction coefficient Br, Bg, Bb to the power, and based on the value of each color component after power correction, A program characterized by setting a shadow color. In claim 3,
The shadow color setting unit is
Linear interpolation is performed on the value of each color component obtained by multiplying the conversion coefficient and the value of each color component after the power correction based on a given interpolation parameter L set according to the brightness of the original color. And the shadow color is set based on the value after linear interpolation. In claim 4,
The shadow color setting unit is
A program characterized in that the interpolation parameter L is obtained based on the maximum value and the minimum value of each color component of the RGB color system constituting the original color. In claim 4 or 5,
The shadow color setting unit is
A color-converted image composed of color components obtained by multiplying the conversion coefficients, a color-corrected image composed of color components obtained by correcting the color components of pixels of the color-converted image to a power, and the interpolation parameter L as an α value A program characterized by alpha blending. In any one of Claims 1-6,
The color composition unit
A program characterized in that the original image and a shadow color image obtained by drawing each pixel of the original image with the shadow color are α-blended using an α value obtained from the shadow information. A program for generating an image of an object space viewed from a given viewpoint,
A texture mapping unit for mapping a texture to an object after perspective transformation;
As a drawing unit that draws an object to which the texture is mapped and generates an image,
Make the computer work,
The texture mapping unit is
Based on the shadow information of the object, an original image of the object generated using a given original color and a shadow color image of the object generated using a shadow color corresponding to the original color, A program characterized by texture-mapping the texture generated by α blending. In claim 8,
The shadow color is obtained by multiplying each color component of the RGB color system constituting the original color by a given conversion coefficient,
The relationship is Kb>Kr> Kg, where Kr is the transform coefficient multiplied by the R component, Kg is the transform coefficient multiplied by the G component, and Kb is the transform coefficient multiplied by the B component. Program. In claim 9,
The shadow color is obtained by performing a power correction to a power of a given correction coefficient Br, Bg, Bb on the value of each color component obtained by multiplying the conversion coefficient. Program to do. In claim 10,
The shadow color is obtained by multiplying the value of each color component obtained by multiplying the conversion coefficient and the value of each color component after the power correction by a given interpolation parameter L set according to the lightness of the original color. A program characterized by being obtained by linear interpolation based on the above. In claim 11,
The program according to claim 1, wherein the interpolation parameter L is obtained based on a maximum value and a minimum value of each color component of the RGB color system constituting the original color.   An information storage medium readable by a computer, wherein the program according to any one of claims 1 to 12 is stored. An image generation system for generating an image of an object space viewed from a given viewpoint,
A drawing unit for drawing an object after perspective transformation to generate an original image;
A shadow color setting unit that sets a shadow color corresponding to the original color based on the original color that is the color of each pixel of the original image;
A shadow information calculation unit for obtaining shadow information of the object;
A color synthesis unit that synthesizes the original color and the shadow color corresponding to the original color based on the shadow information;
An image generation system comprising: An image generation system for generating an image of an object space viewed from a given viewpoint,
A texture mapping unit for mapping a texture to an object after perspective transformation;
A drawing unit that draws an object to which the texture is mapped to generate an image;
Including
The texture mapping unit is
Based on the shadow information of the object, an original image of the object generated using a given original color and a shadow color image of the object generated using a shadow color corresponding to the original color, An image generation system, wherein texture mapping is performed on the texture generated by α blending.

Images