JP4804120B2 - Program, information storage medium, and image generation system - Google Patents

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 that can be viewed from a virtual camera (a given viewpoint) in an object space (virtual three-dimensional space) in which an object such as a character is set is known. It is popular as a place to experience so-called virtual reality.

  In such an image generation system, an effect color may be reflected on an object arranged in the object space to display a scene with fog, haze, smoke, dust, or the like. In this case, in order to improve the virtual reality of the player, it is desirable to change the density of the effect color according to the distance from the virtual camera (viewpoint) to express the real world fog characteristics and the like. As a technique for controlling the density of the effect color, there is a conventional technique disclosed in Japanese Patent Laid-Open No. 2003-323630.

However, in the conventional image generation system, the change in the density of the effect color is only controlled by the α value (the amount of fog) according to the distance from the virtual camera, and there is a limit to the image expression by the fog effect. .
JP 2003-323630 A

  The present invention has been made in view of the problems as described above, and an object of the present invention is to add another change characteristic to an effect color density change characteristic according to the distance from the virtual camera. The present invention provides a program, an information storage medium, and an image generation system capable of further increasing the reality by increasing the effect color and thereby realizing the image expression with a light processing load. is there.

(1) The present invention includes a field-of-view image generation unit that generates a field-of-view image viewed from a virtual camera by projecting an object set in an object space onto a screen;
A post-effect processing unit that performs post-effect processing for adjusting the color of the view image,
The post-effect processing unit
Set a post-effect area for the screen,
First color adjustment information for changing the gradation of the first effect color in a part or the whole of the post-effect area, and a second for changing the first effect color according to the depth value of the view field image And color adjustment information for
Based on the first color adjustment information and the second color adjustment information, the color of the view image is adjusted by reflecting the first effect color in an area corresponding to the post effect area of the view image. The present invention relates to an image generation system characterized by performing post-effect processing.

  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 a computer-readable information storage medium that stores (records) a program that causes a computer to function as each unit.

  In the present invention, the field-of-view image may be image data at a stage output to the frame buffer, or may be image data at an intermediate stage output to an intermediate buffer such as a work buffer as a previous stage output to the frame buffer. Good.

  In post-effect processing, the effect color may be reflected in the image data of the view image output to the frame buffer, or the effect color may be reflected in the image data of the view image output to the work buffer. The image data may be output to the frame buffer.

  In addition, the post-effect processing for adjusting the color for the view image is not only for directly adjusting the color for the view image, but also for the view image after other color adjustment processing is added. Including adjusting. Also, reflecting the first effect color in the view image means that the first effect color is directly reflected in the view image and the first view color is added to the view image after other color adjustment processing or the like is added. Including reflecting the effect color.

  Further, the depth value of the view image can be the Z value of the view image stored in the Z buffer, or predetermined distance information obtained by converting the Z value.

  According to the present invention, the first effect color can be reflected in the visual field image by the change characteristic in which the change characteristic of the effect color that changes in gradation in the predetermined region is added to the change characteristic of the effect color according to the depth value. it can. For example, if an area near the horizon or horizontal line of the view image is set as a post-effect area, the sky color can be changed in gradation as the distance from the horizon or horizontal line increases.

  Therefore, in an area such as the sky in which the depth value is set to be the most distant view, the reflection of the effect color cannot be changed only by the color adjustment information according to the depth value of the view field image. For example, changes in the color of the sky near the horizon or the horizon can be expressed.

  Moreover, when an object on the near side is present in the post-effect area set for the screen, the first effect color is adjusted by the second color adjustment information corresponding to the depth value of the view field image. . Therefore, even if the gradation of the first effect color is changed in the post effect area, it does not look unnatural.

  Furthermore, in the conventional image generation system, when expressing changes in the color of the sky near the horizon or the horizontal line, a sphere or the like is set in a region corresponding to the sky, and the normal vector of the celestial sphere is set. Based on the direction and the direction of the line of sight of the virtual camera, calculations for adjusting changes in the sky color are performed. However, according to the present invention, a change in the color of the sky near the horizon or the horizon can be realistically expressed with a light processing load without adopting such a method.

(2) In the image generation system, program, and information storage medium according to the present invention,
In the invention of (1),
The post-effect processing unit
A first α value is set as the first color adjustment information, and a second α value is set as the second color adjustment information.
The post-effect processing may be performed on the field-of-view image by performing α blending based on a multiplication result of the first α value and the second α value.

  According to the present invention, the depth is obtained by performing α blending based on the multiplication result of the first α value that changes the gradation of the first effect color and the second α value corresponding to the depth value of the view field image. The first effect color can be reflected in the field-of-view image by a change characteristic in which an effect color change characteristic that changes gradation in a predetermined region is added to the effect color change characteristic corresponding to the value.

(3) In the image generation system, the program, and the information storage medium according to the present invention,
In any of the inventions of (1) and (2),
The post-effect processing unit
The post effect area may be set based on the control information of the virtual camera.

  In the present invention, the post-effect area can be set based on control information related to the position, orientation, and angle of view of the virtual camera, and information obtained based on the information. Setting the post-effect area may be such that the reference position of the post-effect area may be set, or the range of the post-effect area may be set.

  According to the present invention, when the position on the screen of the area to be subjected to post-effect processing changes due to the change in the position, orientation, and angle of view of the virtual camera, the change in the position, orientation, and angle of view of the virtual camera. The post-effect area can be set to match.

  For example, if the position of the virtual camera becomes higher or the orientation of the virtual camera becomes upward, the horizon and horizontal lines projected on the screen are relatively positioned below the screen. Therefore, by setting the post-effect area according to changes in the position, orientation, and angle of view of the virtual camera, even if the position, orientation, and angle of view of the virtual camera change, for example, the post-effect processing near the horizon or the horizontal line It can be a target area.

(4) In the image generation system, the program, and the information storage medium according to the present invention,
In any one of the inventions of (1) to (3),
The post-effect processing unit
The coordinate information in the screen coordinate system corresponding to the height information is acquired based on the height information from the predetermined reference plane of the object space, and the post-effect area is set based on the acquired coordinate information. Good.

  In the present invention, for example, the post-effect processing unit may acquire coordinate information calculated by a calculation unit such as a CPU, or the post-effect processing unit may acquire coordinate information by calculating the coordinate information. It may be.

  The height information from the predetermined reference plane of the object space can be arbitrarily determined according to the object arrangement in the object space, the movement range of the virtual camera, and the like.

  According to the present invention, for example, coordinate information in the screen coordinate system corresponding to predetermined height information in the object space can be used as a reference when setting the post-effect area. Therefore, when the position on the screen of the area that should be subject to post-effect processing changes due to changes in the position, orientation, and angle of view of the virtual camera, posts are made according to changes in the position, orientation, and angle of view of the virtual camera. The effect area can be set.

(5) In the image generation system, the program, and the information storage medium according to the present invention,
In any one of the inventions of (1) to (4),
The post-effect processing unit
The first color adjustment information may be set so that the gradation changes from one end to the other end of the gradation adjustment area that is a part of the post-effect area.

  According to the present invention, the first effect color can be reflected in the view field image so that the first effect color changes in gradation from one end to the other end of the gradation adjustment region.

(6) In the image generation system, the program, and the information storage medium according to the present invention,
In the invention of (5),
The post-effect processing unit
As the process of setting the first color adjustment information, a process of drawing a first polygon in which different α values are set for the vertex on one end side and the vertex on the other end side may be performed.

  In the present invention, the first polygon may be, for example, a rectangular polygon having a certain size corresponding to the horizontal width of the screen. Here, “corresponding to the horizontal width of the screen” may be a polygon whose horizontal width is equal to the horizontal width of the screen, or may be a polygon whose width is slightly wider or narrower than the horizontal width of the screen.

  According to the present invention, the density of the first effect color can be changed in gradation in the gradation adjustment region by the α value set for the vertex of the polygon. For example, if the α values set at the upper right and upper left vertices of a rectangular polygon are 0.0 (transparent) and the α values set at the lower right and lower left vertices are 1.0 (opaque), The alpha value is linearly interpolated from the upper end to the lower end of one polygon, so that the density of the first effect color gradually increases.

(7) In the image generation system, the program, and the information storage medium according to the present invention,
In any of the inventions of (5) and (6),
The post-effect processing unit
The first color adjustment information may be set to color adjustment information set at the other end of the gradation adjustment area in an area other than the gradation adjustment area in the post-effect area.

  According to the present invention, in the post-effect area, the change characteristics of the first color adjustment information (first α value) can be made continuous between the gradation adjustment area and the other areas. Therefore, it is possible to prevent an unnatural image from being generated due to abrupt changes in the color adjustment information (for example, α value) that is set in the gradation adjustment region and other regions.

  In the area where the depth value of the visual field image is on the near side, the post-effect area is finally set by the second color adjustment information (for example, the second α value) corresponding to the depth value of the visual field image. Color adjustment information (for example, α value) is set to 0 or a value close to 0. Therefore, even if the first color adjustment information (for example, the first α value) is fixedly set for an area other than the gradation adjustment area, the first effect color of the area where the depth value is on the near side is set. The concentration can be 0 or very low.

(8) In the image generation system, the program, and the information storage medium according to the present invention,
In the invention of (7),
The post-effect processing unit
As the processing for setting the post-effect area, color adjustment information at the other end of the gradation adjustment area is set for all vertices, and a second area corresponding to an area other than the gradation adjustment area in the post-effect area. You may make it perform the process which draws a polygon.

  In the present invention, the second polygon may be a polygon whose horizontal width is equal to the horizontal width of the screen, or may be a polygon whose horizontal width is slightly wider or narrower than the horizontal width of the screen. The size of the second polygon may be changed according to the setting position or setting range of the gradation adjustment area.

  According to the present invention, the α value set for the vertex of the polygon is fixed by setting the α value in the region other than the gradation adjustment region in the post-effect region to the α value at the other end of the gradation adjustment region. be able to.

(9) In the image generation system, the program, and the information storage medium according to the present invention,
In any one of the inventions (1) to (8),
The post-effect processing unit
Setting third color adjustment information for changing the second effect color according to the depth value of the view field image;
Based on the third color adjustment information, post-effect processing for adjusting the color of the visual field image by reflecting the second effect color in the entire region of the visual field image may be further performed.

  According to the present invention, in addition to the first effect color, the second effect color different from the first effect color can be reflected in the entire region of the view field image according to the depth value. Therefore, it is possible to perform a delicate image expression in which the first effect color in the post-effect adjustment area is merged with the second effect color.

(10) An image generation system according to the present invention includes:
Including a post-effect processing unit that performs post-effect processing for adjusting the color of the field-of-view image obtained by projecting the object set in the object space onto the screen;
The post-effect processing unit
An area including at least one of the horizon and the horizon in the view image is set as a post-effect area,
In the post effect area, the first effect color is changed in gradation so that the first effect color becomes lighter as it moves away from at least one of the horizon and the horizontal line, and the first effect color is changed according to the depth value of the visual field image. One effect color may be changed, and post-effect processing for reflecting the first effect color in the view field image may be performed.

  The present invention also relates to a program that causes a computer to function as the post-effect processing unit. The present invention also relates to a computer-readable information storage medium that stores (records) a program that causes a computer to function as the post-effect processing unit.

  According to the present invention, the first effect color can be reflected in the visual field image by the change characteristic in which the change characteristic of the effect color that changes in gradation in the predetermined region is added to the change characteristic of the effect color according to the depth value. it can. Then, by setting the area near the horizon or the horizontal line of the field-of-view image as the post-effect area, the color of the sky can be changed in gradation as it moves away from the horizon or horizontal line.

  Hereinafter, the present embodiment will be described with reference to the drawings.

  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. In this figure, the present embodiment only needs to include at least the processing unit 100 (or include the processing unit 100 and the storage unit 170), and the other units (functional blocks) may be optional components. it can.

  The operation unit 160 is for the player to input operation data, and the function can be realized by hardware such as a lever, button, steering, shift lever, accelerator pedal, brake pedal, microphone, sensor, or housing. .

  The storage unit 170 serves as a work area such as the processing unit 100 or the communication unit 196, and its function can be realized by hardware such as a RAM.

  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 hardware such as a memory (ROM). The processing unit 100 performs various processes of this embodiment based on a program (data) stored in the information storage medium 180. That is, the information storage medium 180 stores (records and stores) a program for causing the computer to function as each unit (each unit) of the present embodiment (a program for causing the computer to implement each unit).

  The display unit 190 outputs an image generated according to the present embodiment, and the function thereof can be realized by hardware such as a CRT, LCD, or HMD (head mounted display).

  The sound output unit 192 outputs the sound generated by the present embodiment, and its function can be realized by hardware such as a speaker or headphones.

  The portable information storage device 194 stores player personal data, game save data, and the like. As the portable information storage device 194, a memory card, a portable game device, and the like can be considered.

  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 a communication ASIC, It can be realized by a program.

  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 the communication unit 196. You may do it. Use of such an information storage medium of the host device (server) is also included in the scope of the present invention.

  The processing unit 100 (processor) performs various processes such as a game process, an image generation process, and a sound generation process based on operation data from the operation unit 160, a program, and the like. In this case, the processing unit 100 performs various processes using the main storage unit 172 in the storage unit 170 as a work area. The function of the processing unit 100 can be realized by hardware such as various processors (CPU, DSP, etc.) or ASIC (gate array, etc.) and a program (game program).

  The processing unit 100 includes a movement / motion processing unit 110, an object space setting unit 112, a virtual camera control unit 114, a drawing unit 120, and a sound generation unit 130. Note that the processing unit 100 does not need to include all these units (functional blocks), and some of them may be omitted.

  The movement / motion processing unit 110 performs processing for obtaining movement information (position, rotation angle) and motion information (position, rotation angle of each part of the object) of the object (moving body). That is, based on operation data input by the player through the operation unit 160, a game program, or the like, processing for moving an object or moving (motion, animation) is performed.

  The object space setting unit 112 includes various objects (polygons, free-form surfaces, subdivision surfaces, etc.) such as moving objects (characters, cars, tanks, robots), columns, walls, buildings, maps (terrain), and the like. A process for arranging and setting (object) in the object space is performed. More specifically, the position and rotation angle (direction) of the object in the world coordinate system are determined, and the rotation angle (rotation around the X, Y, and Z axes) is determined at that position (X, Y, Z). Arrange objects.

  The virtual camera control unit 114 performs processing for controlling a virtual camera set in the object space. That is, virtual camera information such as the position (X, Y, Z) or rotation (rotation around the X, Y, Z axes) of the virtual camera is obtained, and the virtual camera is controlled (controls the viewpoint position and line-of-sight direction). .

  For example, when a moving object is photographed from behind with a virtual camera, the position or rotation (direction of the virtual camera) of the virtual camera may be controlled so that the virtual camera follows changes in the position or rotation of the moving object. desirable. In this case, the virtual camera is controlled based on information such as the position, direction, or speed of the moving object obtained by the movement / motion processing unit 110. Alternatively, the virtual camera may be rotated at a predetermined angle while being moved along a predetermined movement route. In this case, the virtual camera is controlled based on virtual camera data for specifying the position (movement path) and rotation angle of the virtual camera.

  The drawing unit 120 performs drawing processing based on the results of various processing (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, a vertex list including vertex data (vertex position coordinates, texture coordinates, color data, normal vector, α value, etc.) of each vertex of the object is input and input. Vertex processing (vertex shading) is performed based on the vertex data included in the vertex list. When performing vertex shading, vertex generation processing (tessellation, curved surface division, polygon division) for subdividing a polygon can be performed as necessary. In vertex shading, according to the vertex shader program (first shader program in a broad sense), vertex movement processing, coordinate transformation (world coordinate transformation, camera coordinate transformation), clipping processing, or geometric processing such as perspective transformation is performed. On the basis of 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 vertex shading, and pixel shading (pixel processing and fragment processing in a broad sense) that draws pixels (fragments that configure the display screen) that constitute the display image Is done. In pixel shading, according to the pixel shader program (second shader program), various processes such as texture reading (texture mapping), color data setting / change, translucent composition, anti-aliasing, etc. are performed, and the final display image is displayed. The drawing color of the pixel is determined, and the drawing color of the perspective-transformed object is output (drawn) to the drawing buffer 172. That is, in pixel shading, per-pixel processing for setting or changing image information (color, normal, luminance, α value, etc.) for each pixel of a display image is performed. As a result, an image (frame image) that can be seen from the virtual camera (given viewpoint) in the object space is generated. In addition, when there are a plurality of virtual cameras (viewpoints), a frame image can be generated so that an image seen from each virtual camera can be displayed on one screen as a divided image.

  The drawing buffer 172 and the display buffer 173 are buffers (image buffers) that can store image information in units of pixels, such as a frame buffer and a work buffer, and are secured on the VRAM of the image generation system, for example. In this embodiment, the drawing buffer 172 (back buffer) and the display buffer 173 (front buffer) may be configured as a double buffer, or may be configured as a single buffer or a triple buffer. Alternatively, four or more buffers may be used.

  The drawing unit 120 can perform texture mapping processing, hidden surface removal processing, and α blending processing.

  Here, the texture mapping process is a process of mapping a texture (texel value) stored in the texture storage unit 174 to an object. Specifically, the texture (surface properties such as color and α value) is read from the texture storage unit 174 using the texture coordinates set (given) at the vertices of the object (primitive surface). Then, a texture that is a two-dimensional image or pattern is mapped to the object. In this case, processing for associating pixels and texels, bilinear interpolation (texel interpolation), and the like are performed.

  The hidden surface removal process is realized, for example, by a Z buffer method (depth comparison method, Z test) using a Z buffer 176 (depth buffer) in which the Z value (depth information) of each pixel is stored. That is, when drawing each pixel on the primitive surface of the object, the Z value stored in the Z buffer 176 is referred to. Then, the Z value of the referenced Z buffer 176 is compared with the Z value at the drawing target pixel of the primitive surface, and the Z value of the primitive surface is the front side when viewed from the virtual camera (for example, a large Z value). ), The pixel drawing process is performed and the Z value of the Z buffer 176 is updated to a new Z value.

  The α blending process is a process performed based on the α value (A value), and includes normal α blending, addition α blending, subtraction α blending, and the like. For example, in the case of normal α blending, the following processing is performed.

R _Q = (1−α) × R ₁ + α × R ₂
G _Q = (1−α) × G ₁ + α × G ₂
B _Q = (1−α) × B ₁ + α × B ₂
On the other hand, in the case of addition α blending, the following processing is performed.

R _Q = R ₁ + α × R ₂
G _Q = G ₁ + α × G ₂
B _Q = B ₁ + α × B ₂
In the case of subtractive α blending, the following processing is performed.

R _Q = R ₁ −α × R ₂
G _Q = G ₁ −α × G ₂
B _Q = B ₁ −α × B ₂
Here, R ₁ , G ₁ , B ₁ are RGB components of an image (view image) already drawn in the drawing buffer 172 (frame buffer), and R ₂ , G ₂ , B ₂ are drawing buffers 172. Are RGB components of the image to be drawn. 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 translucency (equivalent to transparency and opacity) information, mask information, or bump information. In the present embodiment, the effect color (fog, cloud, steam) is applied to the view image by setting the R, G, B components of the effect color in R ₂ , G ₂ , B ₂ and performing the α blending process as described above. , Haze, dust, dust, smoke, tornado or dew).

  In particular, in the present embodiment, the drawing unit 120 includes a view image generation unit 122 and a post-effect processing unit 124. The view image generation unit 122 projects an object on a screen to generate a view image. That is, the object (one or a plurality of primitive surfaces) after perspective transformation (after geometry processing) is output to the drawing buffer 172. Further, the post effect processing unit 124 performs post effect processing for adjusting the color of the view image based on the α value as the color adjustment information.

  More specifically, the post-effect processing unit 124 sets the post-effect area for the screen based on the virtual camera control information and the like, and the first effect in part or all of the set post-effect area. A process for setting a first α value for changing the gradation of the color and a second α value for changing the first effect color according to the depth value of the visual field image; Based on the second α value, a process of adjusting the color of the area corresponding to the post-effect area of the visual field image by reflecting the first effect color in the visual field image is performed.

  Specifically, the post-effect processing unit 124 acquires coordinate information in a screen coordinate system corresponding to the height information based on height information from a predetermined reference plane in the object space, and based on the acquired coordinate information. To set a part of the post-effect area as a gradation adjustment area.

  Further, as a process for setting the first α value in the gradation adjustment region, the post-effect processing unit 124 sets different α values for the vertex on the one end side and the vertex on the other end side, and is a constant corresponding to the horizontal width of the screen. A process of drawing the first polygon having the size is performed. In addition, as a process of setting the first α value in the area other than the gradation adjustment area in the post-effect area, the α value at the other end of the first polygon is set for all the vertices, and the areas other than the gradation adjustment area are set. A process of drawing a variable-sized second polygon corresponding to the region is performed.

  Further, the post-effect processing unit 124 uses a texture mapping process as a process for setting the second α value in the post-effect area, and uses the Z value of each pixel of the view field image stored in the Z buffer 176 or the Z value. Based on a depth value such as distance information obtained by converting the value, a process of setting an α value corresponding to the depth value and R, G, and B components of the effect color is performed. For example, by performing texture mapping using an LUT (lookup table) for index color / texture mapping stored in the LUT storage unit 179, the second α value corresponding to the depth value of each pixel of the view image The effect color R, G, and B components can be set.

  In this case, the LUT storage unit 179 stores a look-up table for index color / texture mapping that associates the index number with the α value and the effect color, and the post-effect processing unit 124 uses the look-up table for the depth value of the visual field image. The second alpha value corresponding to the depth value of each pixel of the field-of-view image by performing index color / texture mapping on the first polygon and the second polygon using the lookup table And the first effect color.

  Here, when the lookup table for index color / texture mapping is set as 256 colors, the post-effect processing unit 124 sets the Z value of the view image in the Z buffer to a 256-step distance from 0 to 255. It may be converted into information and handled as an index number.

  Further, as the process of setting the third α value, the post-effect processing unit 124 treats the depth value of the view field image as the index number of the lookup table, similarly to the process of setting the second α value. The third alpha value and the second effect color corresponding to the depth value of each pixel of the field-of-view image are obtained by performing index color / texture mapping on the third polygon of screen size or divided screen size using the up table. And set.

The post-effect processing unit 124 then α blends the color of the view image with the colors of the first polygon and the second polygon based on the multiplication result of the first α value and the second α value. Thus, a process of reflecting the first effect color on the view field image is performed. That is, when the first α value is α ₁ and the second α value is α ₂ , the above-described normal α blending and addition α blending are performed using the α value obtained as α = α ₁ × α _2. Alternatively, the subtractive α blending formula is processed. Furthermore, a process for reflecting the second effect color on the view image is performed by α blending the color of the view image and the color of the third polygon based on the third α value.

  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 not only the single player mode but also a multiplayer mode in which a plurality of players can play. The system may also be provided.

  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 using a plurality of terminals (game machine, mobile phone).

2. Next, the method of this embodiment will be described with reference to the drawings. In the following, a case where the post-effect processing method of the present embodiment is applied to fog expression will be mainly described as an example, but the method of the present embodiment can also be applied to image representation other than fog. It is.

2.1 Change in fog density according to distance When generating an image of the object space viewed from a virtual camera, in order to express a more realistic fog effect, the fog density depends on the distance from the virtual camera (viewpoint). It is desirable to change the concentration. That is, the fog effect in the real world can be expressed by increasing the fog density as the distance from the virtual camera increases.

  Therefore, in the present embodiment, a method of setting the α value and the R, G, and B components of the effect color based on the Z value (Z value of the Z buffer) that is a distance parameter from the virtual camera is employed. Specifically, as shown in A1 of FIG. 2, first, the Z value ZP of the view image (image drawn on the drawing buffer) is converted into the depth distance information D (distance information from the virtual camera, the Z value of the view image). To the second Z value obtained by doing so. In the present embodiment, the Z value ZP of the field-of-view image is converted into 256-step depth distance information D from 0 corresponding to the back side when viewed from the virtual camera to 255 corresponding to the front side. Then, as shown in A2, the depth distance information D is converted into an effect color ECP and an α value αP.

  Then, as shown by A3 in FIG. 2, the color ICP (RGB, YUV, etc.) of the view field image and the effect color ECP are α-blended based on αP. As a result, it is possible to generate an image after fog processing to which a fog effect whose fog density changes according to the distance from the virtual camera.

  When the Z value of the Z buffer is converted into the depth distance information D, the minimum value and the maximum value of the depth distance information D are set between the Z value corresponding to the back side and the Z value corresponding to the near side. It can be set arbitrarily.

2.2 Change in fog density according to distance by index color / texture mapping In this embodiment, the process of converting depth distance information D into effect color ECP and α value αP shown in A2 of FIG. It is realized by using color and texture mapping effectively.

  In normal index color / texture mapping, in order to save the storage capacity of the texture storage unit, an index number, not actual color information (RGB), is associated with each texel of the texture as shown in B1 of FIG. Is memorized. Also, as indicated by B2 in FIG. 3, the color information specified by the index number is stored in the index color / texture mapping LUT (color palette). When texture mapping is performed on an object, the LUT is referred to based on the index number of each texture texel, the corresponding color information is read from the LUT, and the read color information is read from the drawing buffer (frame buffer). Etc.).

  In such texture mapping in the index color mode, the number of colors that can be used is smaller (for example, 256 colors) than in texture mapping in the normal mode that does not use the LUT. However, since there is no need to store actual color information (for example, 24-bit color information) in the texture storage unit, the used storage capacity of the texture storage unit can be greatly saved.

  Therefore, in this embodiment, such index color / texture mapping is used in a form different from normal, and the depth distance information D is converted into the α value and the R, G, and B components of the effect color. Therefore, as shown in FIG. 4, in the lookup table LUT2, the α value (0.0 to 1.0) designated by the index number and the R, G, and B components of the effect color (yellow in the LUT2 in FIG. 4). (Single color).

  FIG. 5 is a graph showing the relationship between the index number (depth distance information D) of the LUT 2 stored in the lookup table LUT 2 of this embodiment and the α value. In the graph of FIG. 5, the horizontal axis represents an index number (depth distance information D), and 255 corresponds to the near side and 0 corresponds to the farthest view (back side). In addition, the vertical axis represents the α value, and 256 levels are represented by 0.0 to 1.0. As shown in FIG. 5, in the lookup table LUT2, the index number 0 corresponding to the depth distance information D of the farthest view reflects the effect color darkly as the α value for the depth value on the far side α = 1.0. (255) is associated, and the index number 255 corresponding to the near-side depth distance information D is associated with α = 0.0 (0) that does not reflect the effect color as the α value for the near-side depth value. It has been. Then, as the depth distance information D changes from the near side to the far side, the α value is stored so that the effect color density increases in accordance with the fog density change characteristic.

  Then, as shown in B3 of FIG. 4, the 256-step depth distance information D is treated as an index number of the lookup table LUT2 (the depth distance information D is regarded as an index number), and LUT2 is used to change to B4 of FIG. As shown, index color / texture mapping is performed on a virtual object (for example, display screen size, screen size sprite, polygon). Thereby, the α value corresponding to the depth value of each pixel of the field-of-view image and the R, G, and B components of the effect color can be obtained. Then, as shown in B5, the color of the visual field image and the effect color are α blended based on the α value corresponding to the depth value, and an image in which the effect color is reflected in the entire region of the visual field image is generated.

  For example, the depth distance information D of the visual field image as shown in FIG. 6 is treated as an LUT2 index number, and index color / texture mapping is performed on a screen-sized polygon (third polygon) using the LUT2 of FIG. . Then, as shown in FIG. 7, it is possible to set an α value (third α value) and a yellow effect color (second effect color) corresponding to the depth distance information D of each pixel of the view field image. Then, the screen-size polygon (third polygon) subjected to the index color / texture mapping is α-blended in the drawing buffer 172 in which the field-of-view image is drawn with all α values of the vertex data set to α = 1.0. draw. Then, as shown in FIG. 8, the yellow effect color (second effect color) is reflected in the entire area of the view image according to the depth distance information D of the view image, and follows the change characteristics of the fog density in the real world. An image reflecting the fog effect can be generated.

  In the above example, texture mapping is performed on screen-sized polygons, but texture mapping may be performed on polygons having a size obtained by dividing the screen.

2.3 Post Effect Processing in Gradation Region As described above, in the image generation system according to the present embodiment, the change in fog density is controlled by the α value (fog riding condition) corresponding to the distance from the virtual camera. However, there is a limit to the image expression by the fog effect by such a method. For example, in the image of FIG. 8, in the region F corresponding to the sky, the depth distance information D is set to be constant as the farthest view, so the effect color density (third α value) is set uniformly, The reflection of the effect color (second effect color) cannot be changed.

  Therefore, in the present embodiment, in addition to the post-effect processing in which the effect color (second effect color) is reflected in the entire area of the above-described visual field image, the horizontal width of the partial area of the visual field image is set to the horizontal width of the screen. The corresponding area is set as the gradation adjustment area, and the first effect color is set in the gradation adjustment area in accordance with the first α value for changing the gradation of the first effect color in the area and the depth value of the view field image. And a second α value for changing. Then, based on the multiplication result of the first α value and the second α value, the post effect that adjusts the color of the visual field image by reflecting the first effect color in the region corresponding to the gradation adjustment region of the visual field image Process.

  For example, as shown in FIG. 9, the gradation adjustment area G is set to an area on the screen corresponding to the vicinity of the horizon L of the visual field image of FIG. In the present embodiment, a rectangular first polygon having a fixed size corresponding to the horizontal width of the screen is drawn in an area corresponding to the vicinity of the horizon L of the visual field image of FIG. This first polygon has an α value set to 0.0 (transparent) for the upper right and upper left vertices, and an α value set to 1.0 (opaque) for the lower right and lower left vertices. Yes. Accordingly, the first α value obtained by linearly interpolating the α value 0.0 at the upper end and the α value 1.0 at the lower end is set for each pixel of the first polygon. That is, a first α value that changes in gradation from the upper end to the lower end of the first polygon is set.

  Furthermore, in the area R from the bottom edge of the gradation adjustment area G to the bottom edge of the screen, a rectangular second polygon in which the α value 1.0 at the bottom edge of the gradation adjustment area G is set for all vertices is drawn. To do. Accordingly, the first α value fixed to 1.0 is set for each pixel of the second polygon. Thus, in the present embodiment, the first α value change characteristic is continuous from the upper end of the gradation adjustment region G to the lower end of the screen. In this embodiment, no polygon is set (not drawn) in the area from the upper end of the screen to the upper end of the first polygon, but polygons having an α value of 0.0 are set for all vertices. It may be set.

  Then, similarly to the post-effect processing in which the effect color (second effect color) is reflected in the entire area of the view image described above, the depth distance information D of the view image in FIG. 6 is handled as the index number of the lookup table LUT, Index color / texture mapping is performed on the first polygon and the second polygon using the first effect color lookup table LUT1 prepared separately from the second effect color LUT2. In the LUT 1 used here, the R, G, and B components specified by the index number are set to an orange single color. Further, as shown in FIG. 10, the change characteristic of the second α value specified by the index number is more gradual than the change characteristic of the α value shown in FIG. 5, and the maximum value is 0.7. ing. That is, the second α value is set so that the density of the first effect color in the farthest view does not become as high as the density of the second effect color in the farthest view.

  Then, for each pixel of the first polygon and the second polygon, the first α value set based on the α value set for the vertices of the first polygon and the second polygon, and the index color The α value that is the result of multiplication with the second α value corresponding to the depth distance information D of each pixel of the view field image set by texture mapping is set. Accordingly, as shown in FIG. 11, in the region F corresponding to the farthest view where the second α value is set to the maximum (0.7), at the upper end of the first polygon, the first α value × the second α value = 0.0 × 0.7 = 0.0, and the first effect color is not reflected. However, at the lower end of the first polygon, the first α value × the second α value = 1.0 × 0.7 = 0.7, and the first effect color is reflected deeply. That is, in the region F corresponding to the farthest view, the result of multiplication of the first α value and the second α value is such that the orange color as the first effect color becomes darker toward the bottom of the screen. An α value is set.

  On the other hand, in the region N corresponding to the near side of the farthest view, the first α value is canceled as a result of the multiplication by the second α value corresponding to the depth distance information D of each pixel of the view field image. In the example of FIG. 11, in the gradation adjustment region G in which the first polygon is set, the mountain object M is arranged on the near side of the farthest view, but in the region corresponding to the mountain object M, the near side object is used. Since a small α value (for example, 0.01) is set as the second α value, the first α value set for the first polygon is set to a small value (for example, 0.07). Further, in the region R where the second polygon is set, the terrain object L on the near side is arranged, so that the first α value set for the second polygon is similarly 0 or close to 0. Value. As described above, in the present embodiment, the α value is set so that the first effect color that changes the gradation is reflected in the back object, but the first effect color is not reflected in the near object. can do.

  Then, the first polygon and the second polygon are α blended and drawn in the drawing buffer 172 in which the field-of-view image reflecting the second effect color is drawn. Then, as shown in FIG. 12, the first effect color (orange) in which the second effect color (yellow) corresponding to the depth distance information D is reflected in the entire area of the field-of-view image and the gradation changes in the gradation adjustment area G. An image reflecting the color) can be generated.

2.4 Control of gradation adjustment area In the image generation system according to the present embodiment, the position, orientation, and angle of view of the virtual camera change. When the position, orientation, and angle of view of the virtual camera change, the image is projected onto the screen. The position of the object to be changed also changes, and the position on the screen of the area to be the gradation adjustment area changes. For example, when the position of the virtual camera changes upward from the position where the view image in FIG. 6 is generated, the position of the horizon L in the generated view image moves relatively below the screen. The same applies when the orientation of the virtual camera changes upward, or when the angle of view is narrowed or widened.

  Therefore, in the present embodiment, the gradation adjustment region G is set based on the control information of the virtual camera. Therefore, even if the position on the screen of the region to be the gradation adjustment region G changes due to changes in the position, orientation, and angle of view of the virtual camera, gradation adjustment is performed according to changes in the position, orientation, and angle of view of the virtual camera. Region G can be set.

  FIG. 13 is a conceptual diagram showing the correspondence between the virtual camera CM and the screen SC with respect to the object space OB. In the present embodiment, based on the height information OH from a predetermined reference plane of the object space, coordinate information SH in the screen coordinate system corresponding to the height information OH is acquired, and based on the acquired coordinate information SH. The gradation adjustment area G is set. More specifically, the coordinate information SH is obtained by matrix-converting the height information OH of the world coordinate system into the screen coordinate system, and the first polygon is drawn based on the coordinate information SH.

  Here, the height information OH can be arbitrarily determined according to the object arrangement in the object space OB, the movement range of the virtual camera CM, and the like. In the present embodiment, the height information OH is determined so that the coordinate information SH corresponds to the position of the horizon L in FIG. Accordingly, the position of the horizon L on the screen can be obtained in a pseudo manner according to changes in the position, orientation, and angle of view of the virtual camera. Even if the position, orientation, and angle of view of the virtual camera change, the vicinity of the horizon L The gradation adjustment area G can be set in this area.

  In the present embodiment, a first polygon having a fixed size is drawn with the pixel position of the screen corresponding to the coordinate information SH as the upper end, the vertical width of 30 pixels, and the horizontal width equal to the horizontal width of the screen. Then, the vertical width is set from the lower end of the first polygon to the lower end of the screen, and a second polygon having a variable size equal to the horizontal width of the screen is drawn.

  Further, even if the position, orientation, and angle of view of the virtual camera change greatly, for example, even if the lower end of the first polygon is positioned above the horizon L, gradation adjustment is performed below the first polygon. A second polygon that draws the change characteristic of the first effect color in the region G is drawn. Therefore, even if the position of the coordinate information SH and the horizon L on the screen may be shifted, an unnatural image is generated in which the first effect color is not reflected at the boundary of the line with the first effect color. Can be prevented.

3. Processing of this Embodiment Next, the processing of this embodiment will be described with reference to the flowchart of FIG.

  First, in step S1, a view field image (an object after perspective transformation) is output to a frame buffer.

  In step S2, the Z buffer value of the view field image is converted into 256 steps of depth distance information D and stored in the work buffer.

  In step S3, the depth distance information D of the work buffer is set as an index texture of 256 colors, and the LUT2 for the second effect color is set as an LUT for index color / texture mapping.

  In step S4, the third polygon subjected to the index color / texture mapping using the LUT2 is α blended and drawn in the frame buffer with all α values of the vertex data set to α = 1.0.

  In step S5, the drawing position of the first polygon is obtained.

  In step S6, the depth distance information D of the work buffer is set as an index texture of 256 colors, and the LUT1 for the first effect color is set as the LUT for index color / texture mapping.

  In step S7, the first polygon subjected to index color / texture mapping using LUT1 is obtained with the alpha value of the vertex data set to α = 0.0 at the upper end and α = 1.0 at the lower end. In the frame buffer, α blending is rendered in the frame buffer, and the second polygon subjected to index color / texture mapping is framed at a position determined from the rendering position of the first polygon, with all alpha values of α = 1.0. Draw alpha blending in the buffer.

4). Hardware Configuration Next, an example of a hardware configuration capable of realizing the present embodiment will be described with reference to FIG.

  The main processor 900 operates based on a program stored in the CD 982 (information storage medium), a program transferred via the communication interface 990, or a program stored in the ROM 950 (one of information storage media). Various processes such as processing, image processing, and sound processing are executed.

  The coprocessor 902 assists the processing of the main processor 900, has a product-sum calculator and a divider capable of high-speed parallel calculation, and executes matrix calculation (vector calculation) at high speed. For example, when processing such as matrix calculation is required for physical simulation for moving / moving an object, a program operating on the main processor 900 instructs (requests) the processing to the coprocessor 902. To do.

  The geometry processor 904 performs geometry processing such as coordinate transformation, perspective transformation, light source calculation, and curved surface generation, has a product-sum calculator and a divider capable of high-speed parallel computation, and performs matrix computation (vector computation). Run fast. For example, when processing such as coordinate transformation, perspective transformation, and light source calculation is performed, a program operating on the main processor 900 instructs the geometry processor 904 to perform the processing.

  The data decompression processor 906 performs a decoding process for decompressing the compressed image data and sound data, and a process for accelerating the decoding process of the main processor 900. As a result, a moving image compressed by the MPEG method or the like can be displayed on the opening screen, the intermission screen, the ending screen, or the game screen. Note that the image data and sound data to be decoded are stored in the ROM 950 and the CD 982 or transferred from the outside via the communication interface 990.

  The drawing processor 910 performs drawing (rendering) processing of an object composed of primitives (primitive surfaces) such as polygons and curved surfaces at high speed. When drawing an object, the main processor 900 uses the function of the DMA controller 970 to pass the object data to the drawing processor 910 and transfer the texture to the texture storage unit 924 if necessary. Then, the rendering processor 910 renders the object in the frame buffer 922 at high speed while performing hidden surface removal using a Z buffer or the like based on the object data and texture. The drawing processor 910 can also perform α blending (translucent processing), depth cueing, mip mapping, fog processing, bilinear filtering, trilinear filtering, anti-aliasing, shading processing, and the like. In addition, a programmable shader such as a vertex shader or a pixel shader is also mounted on the drawing processor 910, and creation / change (update) of vertex data and pixel (or fragment) drawing are performed according to the shader program that realizes the method of this embodiment. Make a color 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, and generates high-quality game sounds such as BGM, sound effects, and sounds. The generated game sound is output from the speaker 932.

  Operation data from the game controller 942 (lever, button, chassis, pad type controller, gun type controller, etc.), save data from the memory card 944, and personal data are transferred via the serial interface 940.

  The ROM 950 stores system programs and the like. In the case of the 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 used as a work area for various processors.

  The DMA controller 970 controls DMA transfer between the processor and memory (RAM, VRAM, ROM, etc.).

  The CD drive 980 drives a CD 982 (information storage medium) in which programs, image data, sound data, and the like are stored, and enables access to these programs and data.

  The communication interface 990 is an interface for transferring data to and from the outside via a network. In this case, as a network connected to the communication interface 990, a communication line (analog telephone line, ISDN), a high-speed serial bus, or the like can be considered. By using a communication line, data transfer via the Internet becomes possible. Further, by using the high-speed serial bus, data transfer with other image generation systems becomes possible.

  Note that all the units (units) of the present embodiment may be realized only by hardware, or only by a program stored in an information storage medium or a program distributed via a communication interface. May be. Alternatively, it may be realized by both hardware and a program.

  And when each part of this embodiment is implement | achieved by both hardware and a program, the program for functioning hardware (computer) as each part of this embodiment is stored in an information storage medium. Become. More specifically, the program instructs each processor 902, 904, 906, 910, 930, etc., which is hardware, and passes data if necessary. Each of the processors 902, 904, 906, 910, 930 and the like implements each unit of the present invention based on the instruction and the passed data.

5. Modifications The present invention is not limited to that described in the above embodiment, and various modifications can be made. For example, terms (sprites, polygons, etc.) cited as broad terms (virtual objects) in the description in the specification can be replaced with broad terms in other descriptions in the specification.

  In the above-described embodiment, the example in which the first effect color is changed in gradation by the first α value set based on the α value set at the vertex of the polygon has been described. A gradation texture in which the first effect color changes in gradation may be prepared, and this may be texture-mapped to the first polygon. In this case, the effect is based on the α value of the gradation texture, the α value set at the vertex of the polygon, or the α value as the result of multiplying the α value of the gradation texture and the α value set at the vertex of the polygon. It is possible to α blend the texture color as the color and the color of the view image.

  In the case of using a gradation texture, in order to reflect the second α value corresponding to the depth value, the gradation texture and the index texture may be subjected to the multi-texture mapping using a multi-texture mapping technique. .

  In addition, depending on the game situation (virtual time information on the game, real time information, input information and the type of game event that occurred based on the program, the climate set on the game, etc.) The range of the gradation area G and the height information OH for setting the gradation area G may be changed. Here, when changing the type and change characteristics of the effect color, for example, R, G, B components and α values set in the LUT 1 for the first effect color and the LUT 2 for the second effect color are changed. The change characteristic may be changed, or a plurality of lookup tables LUT may be prepared and the LUT to be used may be changed. Further, when changing the range of the gradation region G, for example, the vertical width of the first polygon may be changed and drawn. By adopting such a configuration, it is possible to express a temporal change from morning to evening, a change in weather, and the like according to the game situation. Further, the type and change characteristics of the effect color and the range of the gradation area G may be changed according to the control information of the virtual camera.

  Also, the blending method of the α value is not limited to the method described in the present embodiment, and various modifications can be made.

  The present invention can also be applied to various games (such as fighting games, competitive games, shooting games, robot battle games, sports games, role-playing games, etc.). The present invention is also applicable to various image generation systems (game 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, and a system board for generating game images. Can be applied.

  In the invention according to the dependent claims of the present invention, a part of the constituent features of the dependent claims can be omitted. Moreover, the principal part of the invention according to one independent claim of the present invention can be made dependent on another independent claim.

The example of a functional block diagram of the image generation system of this embodiment. Explanatory drawing of the method of reflecting an effect color based on (alpha) value according to Z value. Explanatory drawing about index color and texture mapping. Explanatory drawing about index color and texture mapping. Explanatory drawing of LUT of this embodiment. The example of the visual field image produced | generated by the method of this embodiment. The example of the intermediate image produced | generated by the method of this embodiment. The example of the visual field image after the post-effect process produced | generated by the method of this embodiment. The example of the intermediate image produced | generated by the method of this embodiment. Explanatory drawing of LUT of this embodiment. The example of the intermediate image produced | generated by the method of this embodiment. The example of the visual field image after the post-effect process produced | generated by the method of this embodiment. Explanatory drawing of the method of the image generation of this embodiment. The detailed example of the process of this embodiment. Hardware configuration example.

Explanation of symbols

ICP View image color ZP View image Z value FCP Fog color αP Fog α value LUT Lookup table D Depth distance information 100 Processing unit 120 Drawing unit 122 View image generating unit 124 Post-effect processing unit 170 Storage unit 172 Drawing buffer 174 Texture storage unit 176 Z buffer 179 LUT storage unit 190 Display unit

Claims (9)

A program for generating an image,
A field-of-view image generation unit that projects an object set in the object space onto a screen and generates a field-of-view image viewed from a virtual camera;
A post-effect area is set for the screen, and the first color adjustment information for changing the gradation of the first effect color in a part or the whole of the post-effect area and the depth value of the visual field image Second color adjustment information for changing the first effect color is set, and based on the first color adjustment information and the second color adjustment information, the post-effect area of the field-of-view image is set in the post-effect area. Causing the computer to function as a post-effect processing unit that performs post-effect processing for adjusting the color of the field-of-view image by reflecting the first effect color in a corresponding region ;
The post-effect processing unit
Based on the control information of the virtual camera, a gradation adjustment area that is a part of the post-effect area is set, and the first color adjustment information is changed in gradation from one end to the other end of the gradation adjustment area. A program characterized by setting as follows . In claim 1,
The post-effect processing unit
A first α value is set as the first color adjustment information, and a second α value is set as the second color adjustment information.
A program that performs the post-effect processing on the field-of-view image by performing α blending based on a multiplication result of the first α value and the second α value. In any one of Claims 1 and 2 ,
The post-effect processing unit
Acquiring coordinate information in a screen coordinate system corresponding to the height information based on height information from a predetermined reference plane of the object space, and setting the gradation adjustment region based on the acquired coordinate information Program to do. In any one of Claims 1-3 ,
The post-effect processing unit
A program characterized in that, as the process of setting the first color adjustment information, a process of drawing a first polygon in which different α values are set for a vertex on one end side and a vertex on the other end side is performed. In any one of Claims 1-4 ,
The post-effect processing unit
The program according to claim 1, wherein the first color adjustment information is set to color adjustment information set at the other end of the gradation adjustment area in an area other than the gradation adjustment area in the post-effect area. In claim 5 ,
The post-effect processing unit
As the processing for setting the post-effect area, color adjustment information at the other end of the gradation adjustment area is set for all vertices, and a second area corresponding to an area other than the gradation adjustment area in the post-effect area. A program characterized by performing a process of drawing a polygon. In any one of Claims 1-6 ,
The post-effect processing unit
Setting third color adjustment information for changing the second effect color according to the depth value of the view field image;
A program that further performs post-effect processing for adjusting the color of the visual field image by reflecting the second effect color in the entire region of the visual field image based on the third color adjustment information. A computer-readable information storage medium, wherein the program according to any one of claims 1 to 7 is stored. An image generation system,
A field-of-view image generation unit that projects an object set in the object space onto a screen and generates a field-of-view image viewed from a virtual camera;
A post-effect area is set for the screen, and the first color adjustment information for changing the gradation of the first effect color in a part or the whole of the post-effect area and the depth value of the visual field image Second color adjustment information for changing the first effect color is set, and based on the first color adjustment information and the second color adjustment information, the post-effect area of the field-of-view image is set in the post-effect area. A post-effect processing unit that performs post-effect processing for adjusting the color of the view image by reflecting the first effect color in a corresponding region ,
The post-effect processing unit
Based on the control information of the virtual camera, a gradation adjustment area that is a part of the post-effect area is set, and the first color adjustment information is changed in gradation from one end to the other end of the gradation adjustment area. An image generation system characterized by setting as described above .