JP5253118B2 - Image generation system, program, and information storage medium - Google Patents

Description

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

  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 that is a virtual three-dimensional space is known, and is popular as a so-called virtual reality experience. Is expensive. Taking an image generation system capable of enjoying a fighting game as an example, a player performs operations (attack operation, defense operation, movement operation, etc.) related to a moving body (character, etc.) using an operation unit (game controller, etc.). Enjoy a game of fighting with the moving bodies of other players (including computer players).

By the way, regarding the above-described image generation system, a method for generating an image having a high visual effect by synthesizing an effect image representing particles such as flame, smoke, and flash light with an original image obtained by viewing the object space from a virtual camera. However, since many effect images have a heavy processing load at the time of drawing, a method of combining the original image with a resolution of the effect image lower than that of the original image has been proposed (Non-Patent Document). 1).
Masaki Kawase, real-time CG expression technique in mud OUBLE-STEAL 煤 A [online], 2002, Bunka Co., Ltd. Game Development Division, [searched November 14, 2008], Internet <URL: http: // www.bunkasha-games.com/cedec2002/kawase_ppt.html>

  However, with such a conventional method, although the processing load when drawing the effect image is reduced, the resolution of the original image in the area overlapping with the effect image is also lowered, so that the image is deteriorated. There was a problem.

  The present application has been made in view of the above circumstances, and an object of the present application is an image generation system, a program, and a program that can avoid image degradation while reducing the processing load when rendering an effect image. An object is to provide an information storage medium.

(1) The present invention
An image generation system for generating an image,
An original image drawing unit that performs processing of drawing an original image obtained by viewing an object set in the object space from a virtual camera in the first color buffer;
An effect processing unit that performs effect processing for combining the original image and an effect image for adjusting the color of the original image;
The effect processing unit as the effect processing,
Processing to draw the original image drawn in the first color buffer in a second color buffer having a resolution lower than that of the first color buffer;
Drawing the effect image in the second color buffer;
Processing to draw a stencil image for designating pixels for drawing the effect image in a stencil buffer having a resolution higher than that of the second color buffer based on the depth value of the original image and the depth value of the effect image;
Processing to draw the effect image drawn in the second color buffer in the first color buffer based on the stencil image;
It is related with the image generation system characterized by performing. The present invention also relates to a program that causes a computer to function as each of the above-described units, and a computer-readable information storage medium that stores such a program.

  In the present invention, since the stencil image is drawn based on the depth value of the original image and the depth value of the effect image, when the object overlaps the effect image as viewed from the virtual camera, the pixel corresponding to the object Is designated as a pixel that is not drawn, and a stencil image that is designated as a pixel to be drawn is drawn for a pixel corresponding to an effect image that does not overlap the object. Therefore, according to the present invention, in such a case, among the pixels of the first color buffer, for the pixel corresponding to the object overlapping before the effect image when viewed from the virtual camera, the original image drawn in the first color buffer is the same. For the remaining pixels corresponding to the effect image that does not overlap the object, the effect image drawn in the second color buffer is drawn. Thus, according to the present invention, it is possible to avoid image degradation while reducing the processing load when rendering an effect image.

(2) In the image generation system, program, and information storage medium of the present invention,
The effect processing unit
You may make it perform the process which sets the position of the said effect image behind a specific object seeing from the said virtual camera.

  In this way, since the plurality of effect images are not set to overlap the specific object before and behind the specific object when viewed from the virtual camera, when the effect image is drawn in the second color buffer, Even if drawing is not performed based on the depth value of the original image and the depth value of the effect image, it is possible to avoid image degradation due to the stencil image.

(3) In the image generation system, program, and information storage medium of the present invention,
The effect processing unit
A process of drawing the effect image in the second color buffer may be performed based on the depth value of the original image and the depth value of the effect image.

  In this way, even if a plurality of effect images are set to overlap the specific object when viewed from the virtual camera in front and behind the specific object, when the effect image is drawn in the second color buffer, By rendering based on the depth value and the depth value of the effect image, it is possible to avoid degradation of the image due to the stencil image while accurately rendering these front-rear relationships.

(4) In the image generation system, program, and information storage medium of the present invention,
The effect processing unit
A first effect process for performing the effect process on a first effect image set in front of the specific object when viewed from the virtual camera, and a second effect set at the back of the specific object as viewed from the virtual camera. You may make it perform the 2nd effect process which performs the said effect process about an effect image.

  In this way, even if the first effect image and the second effect image are set to overlap the specific object when viewed from the virtual camera before and behind the specific object, the first effect processing for the first effect image is performed. And the second effect processing for the second effect image, when the effect image is drawn in the second color buffer, it is not necessary to draw based on the depth value of the original image and the depth value of the effect image. The stencil image can avoid the deterioration of the image while accurately drawing these contexts.

(5) In the image generation system, program, and information storage medium of the present invention,
The effect processing unit
Mapping the effect texture to the effect object to render the effect image in the second color buffer;
A process of drawing the stencil image in the stencil buffer may be performed based on the depth value of the effect object.

  In this way, it is possible to reduce the processing load when drawing a stencil image.

(6) Further, in the image generation system, program and information storage medium of the present invention,
The effect processing unit
A process of drawing the stencil image in the stencil buffer may be performed based on the shape of the effect object.

  In this way, the processing load when drawing a stencil image can be further reduced.

(7) In the image generation system, program, and information storage medium of the present invention,
The effect processing unit
A process of drawing the stencil image in the stencil buffer may be performed based on the effect texture.

  In this way, the detailed stencil image corresponding to the texture for the effect is drawn, so that deterioration of the image can be further avoided.

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

1. 1. First embodiment 1-1. Configuration FIG. 1 shows an example of a functional block diagram of the image generation system (game system) of the first 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 10 is for a player to input operation data of a player object (an example of a moving object, a player character operated by the player, etc.), and its functions are lever, button, steering, microphone, touch panel type. It can be realized by a display or a housing.

  The storage unit 20 serves as a work area for the processing unit 100, the communication unit 70, and the like, and its functions can be realized by a RAM (main memory 22), a VRAM (video memory 24), or the like.

  An information storage medium 30 (a computer-readable medium) stores programs, data, and the like, and functions as an optical disk (CD, DVD), a magneto-optical disk (MO), a magnetic disk, a hard disk, and a 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 30. That is, the information storage medium 30 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 portable information storage device 40 stores player personal data, game save data, and the like. The portable information storage device 40 can be realized by a memory card, a portable game device, or the like.

  The display unit 50 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 60 outputs the sound generated by the present embodiment, and its function can be realized by a speaker, headphones, or the like.

  The communication unit 70 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 the present embodiment is transmitted from the information storage medium of the host device (server) to the information storage medium 30 (or the main memory of the storage unit 20) via the network and communication unit 70. 22). 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 10. Here, the game process includes a process for starting a game when a game start condition is satisfied, a process for advancing the game, a process for generating an event when the event generation condition is satisfied, and an object such as a character or a map. There are a process for arranging, a process for displaying an object, a process for calculating a game result, a process for ending a game when a game end condition is satisfied, and the like. The processing unit 100 performs various processes using the main memory 22 in the storage unit 20 as a work area. The functions of the processing unit 100 can be realized by hardware such as various processors (CPU (main processor), GPU (drawing processor), 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, a drawing unit 120, and a sound generation unit 130. Note that some of these may be omitted.

  The object space setting unit 110 represents display objects such as a character, a car, a building, a tree, a pillar, a wall, a course (road), and a map (terrain) based on the object data stored in the object data storage unit 22A. Various kinds of objects (objects composed of primitives such as polygons, free-form surfaces or subdivision surfaces) and light sources indicating the direction, intensity and color of light travel are set in the object space. That is, the position and rotation angle (synonymous with direction and direction) of the object in the world coordinate system are determined, and the determined rotation angle (about the X, Y, and Z axes) is determined at the determined position (X, Y, Z). Rotate the object and light source.

  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, the object is moved in the object space or the object is moved (motion, animation) based on the operation data input by the player through the operation unit 10, the program (movement / motion algorithm), various data (motion data), or the like. ) Is performed. Specifically, object movement information (position, rotation angle, speed, or acceleration) and motion information (position or rotation angle of each part that constitutes the object) are sequentially transmitted every frame (1/60 seconds). Perform the required simulation process. 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, processing for controlling the position (X, Y, Z) or rotation angle (rotation angle about the X, Y, Z axis) of the virtual camera (processing for controlling the viewpoint position, the line-of-sight direction or the angle of view) I do.

  For example, when an object (for example, a character or a car) is photographed from behind with a virtual camera, the position or rotation angle (the direction of the virtual camera) of the virtual camera is set so that the virtual camera follows changes in the position or rotation of the object. Control. In this case, the virtual camera can be controlled based on information (an example of predetermined control information) such as the position, rotation angle, or speed of the object obtained by the movement / motion processing unit 112. Alternatively, control may be performed such that the virtual camera is rotated at a predetermined rotation angle or moved along a predetermined movement path. In this case, the virtual camera is controlled based on virtual camera data (an example of predetermined control information) 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 drawing 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 50. When generating a so-called three-dimensional game image, first, object data (model data) including vertex data (vertex position coordinates, texture coordinates, color data, normal vector, α value, etc.) of each vertex of the object (model) ) Is input from the object data storage unit 22A, and vertex processing (shading by a vertex shader) is performed based on the vertex data included in the input object data. When performing the vertex processing, vertex generation processing (tessellation, curved surface division, polygon division) for re-dividing the polygon may be performed as necessary. In the vertex processing, according to the vertex processing program (vertex shader program, first shader program), vertex movement processing, coordinate conversion (world coordinate conversion, camera coordinate conversion), clipping processing, perspective processing, and other geometric processing are 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 the vertex processing, and the surface of the polygon (primitive) is associated with the pixel (pixel). Subsequent to rasterization, pixel processing (shading or fragment processing by a pixel shader) for drawing pixels (fragments forming a display screen) constituting an image is performed. In pixel processing, according to a pixel processing program (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 an image is processed. The drawing color of the pixel to be configured is determined, and the drawing color of the perspective-transformed object is rendered as a rendering target (a buffer capable of storing image information in units of pixels. The frame buffer 22B of the main memory 22; the first color buffer 24A of the video memory 24; 2nd color buffer 24B, stencil buffer 24E, etc.). That is, in pixel processing, per-pixel processing for setting or changing image information (color (color value, luminance value), normal, α value, etc.) in units of pixels is performed. Thereby, an image that can be seen from the virtual camera (given viewpoint) in the object space is generated. Note that when there are a plurality of virtual cameras (viewpoints), an image can be generated so that an image seen from each virtual camera can be displayed as a divided image on one screen.

  The vertex processing and pixel processing are realized by hardware that enables polygon (primitive) drawing processing to be programmed by a shader program written in a shading language, so-called programmable shaders (vertex shaders and pixel shaders). Programmable shaders can be programmed with vertex-level processing and pixel-level processing, so that the degree of freedom of drawing processing is high, and expressive power is greatly improved compared to conventional hardware-based fixed drawing processing. Can do.

  The drawing unit 120 performs geometry processing, texture mapping, hidden surface removal processing, α blending, stencil test, and the like when drawing an object.

  In the geometry processing, processing such as coordinate conversion, clipping processing, perspective projection conversion, or light source calculation is performed on the object. Then, object data (positional coordinates of object vertices, texture coordinates, color data (luminance data), normal vector, α value, etc.) after geometry processing (after perspective projection conversion) is stored in the object data in the main memory 22. Stored in the part 22A.

  For light source calculation, various parameters set for the light source (light source intensity, color, position, light source vector, etc.), various parameters set for objects (primitives) and vertices (vectors such as reflection attributes, normals, etc.) Then, light reflection is simulated based on various parameters (gaze vector, viewpoint position, etc.) set in the virtual camera, and a basic color (diffuse) and a specular reflection component (specular) are obtained for each vertex.

  Texture mapping is a process for mapping a texture (texel value, UV coordinate value) stored in the texture storage unit 24C of the video memory 24 to an object. Specifically, the texture (surface properties such as color (RGB) and α value) is read from the texture storage unit 24C of the video memory 24 using the texture coordinates set (given) at 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 with texels, bilinear interpolation, trilinear interpolation, etc. are performed as texel interpolation.

  As the hidden surface removal processing, hidden surface removal processing is performed by a depth comparison method (depth test, Z test) using a depth buffer 24D (depth buffer) in which the depth value (Z value) of the drawing pixel is stored. That is, when drawing pixels corresponding to the primitives of the object are drawn, the depth value stored in the depth buffer 24D is referred to for each pixel. Then, the depth value of the referenced depth buffer 24D is compared with the depth value at the primitive drawing pixel, and the depth value at the drawing pixel is the front side when viewed from the virtual camera (for example, a small depth value). If it is, the drawing process of the drawing pixel is performed, and the depth value of the depth buffer 24D is updated to a new depth value.

  As the α blending, a translucent synthesis process (usually α blending, addition α blending, subtraction α blending, or the like) based on the α value (A value) is performed. 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. In the case of simple addition, α = 1 and the following formulas (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. In the case of simple subtraction, α = 1 and the following formulas (7) to (9) are processed.

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 and B ₁ are RGB components (color values) of an image (original image) already drawn in the frame buffer 22B or the first color buffer 24A and the second color buffer 24B, and R ₂ , G ₂ , and B ₂ are RGB components of an image to be drawn in the frame buffer 22B or the first color buffer 24A and the second color buffer 24B. 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.

  As the stencil test, the value of the stencil buffer 24E (stencil image) and the stencil reference value that can be arbitrarily set are compared for each pixel based on a comparison function that can be arbitrarily set, and the image of the first color buffer 24A Processing for determining whether to use or discard the data of each pixel of the image of the two-color buffer 24B in the subsequent processing is performed. For example, for the pixel in which “1” is stored among the pixels in the stencil buffer 24E, the color in the second color buffer 24B is used in the subsequent processing, and the pixel in which “0” is stored among the pixels in the stencil buffer 24E. The color of the second color buffer 24B can be prevented from being used in the subsequent processing.

  In the present embodiment, the drawing unit 120 includes an original image drawing unit 122 and an effect processing unit 124.

  As described above, the original image drawing unit 122 performs a process of drawing the original image obtained by viewing the object space from the virtual camera in the first color buffer 24A.

  Based on the result of the game process performed by the processing unit 100, the effect processing unit 124 synthesizes an effect image that expresses flame, smoke, flash, or the like with the original image when an event such as an explosion or a fire occurs. Process.

  Specifically, as the effect processing, the effect processing unit 124 first has a lower resolution than the first color buffer 24A for the colors (RGB components) of the pixels constituting the original image drawn in the first color buffer 24A (see FIG. A process of drawing (copying) in the second color buffer 24B (reduction buffer) having a small number of pixels and a small size is performed. In the present embodiment, the resolution of the second color buffer 24B is half the resolution of the first color buffer 24A (the number of pixels and the size is a quarter).

  Then, the effect processing unit 124 performs processing for drawing an effect image for adjusting the color of the original image in the second color buffer 24B. More specifically, the effect processing unit 124 functions as the object space setting unit 110 described above, and uses a rectangular polygon at a position (world coordinate system) where an explosion or a flame occurs in the object space determined by the result of the game processing. Set the configured effect object. Then, the effect processing unit 124 performs the above-described geometry processing on the effect object, maps the effect texture that expresses flame, smoke, flash, or the like to the effect object, and performs the effect image without performing the depth test. A drawing process is performed in the second color buffer 24B.

  Then, the effect processing unit 124 draws the stencil image that specifies the pixel for drawing the effect image in the first color buffer 24A in the stencil buffer 24E having a higher resolution than the second color buffer 24B based on the shape of the effect object. Perform the process. In this embodiment, the resolution of the stencil buffer 24E is twice the resolution of the second color buffer 24B (the number of pixels and the size is four times), and is the same as the resolution of the first color buffer 24A.

  Specifically, the effect processing unit 124 functions as the object space setting unit 110 described above, and sets an effect object at a position (world coordinate system) where an explosion or a flame has occurred in the object space determined by the result of the game processing. To do. Then, the effect processing unit 124 performs the above-described geometry processing on the effect object, and the depth value of the original image stored in the depth buffer 24D and the depth value included in the position of the effect object set by the effect processing unit 124. While performing the depth test based on the comparison result with (an example of the depth value of the effect image), a process of drawing the shape of the effect object visible from the virtual camera in the stencil buffer 24E as a stencil image is performed. In the present embodiment, the effect processing unit 124 stores “1” for the pixel in the stencil buffer 24E where the effect object is closest, and stores “0” for the pixel whose effect object is not closest. Thus, a stencil image is drawn.

  The effect processing unit 124 may perform processing for setting the position of the effect object (an example of the position of the effect image) so that it is always behind the specific object (such as a character) when viewed from the virtual camera. Good. In this case, the effect processing unit 124 sets the position of the effect object so that it is always behind the specific object when viewed from the virtual camera, based on the position of the virtual camera and the position of the specific object. Alternatively, the position and moving range of the effect object may be set in advance in an area that is always behind the specific object as viewed from the virtual camera.

  Then, the effect processing unit 124 performs a process of drawing the effect image drawn in the second color buffer 24B as described above in the first color buffer 24B while performing a stencil test based on the stencil image. In the present embodiment, the effect processing unit 124 draws the color of the second color buffer 24B in the first color buffer 24A for the pixel in which “1” is stored in the stencil image, and “0” is stored in the stencil image. The remaining pixels are left as they are without updating the color of the original image in the first color buffer 24A.

  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 60.

  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).

1-2. Next, the method of the present embodiment will be described with reference to the drawings while comparing with the conventional method.

1-2-1. Conventional Technique FIG. 2 is a diagram for explaining a technique that is employed in a conventional image generation system to reduce the processing load when drawing an effect image. FIG. 2 illustrates an example in which an effect image that expresses smoke is synthesized behind a black spherical object (an example of a specific object) as viewed from the virtual camera. First, as shown in A1 of FIG. 2, in the conventional method, the color of each pixel of the original image obtained by viewing the spherical object set in the object space from the virtual camera has the resolution of the final display image. The depth value of each pixel of the original image drawn in 24A is stored in the first depth buffer 24D1 having the same resolution as the first color buffer 24A.

  Then, as shown in A2 of FIG. 2, the color of each pixel of the original image drawn in the first color buffer 24A is reduced and copied to the second color buffer 24B having a resolution twice that of the first color buffer 24A. The depth value of each pixel of the original image drawn in the first depth buffer 24D1 is reduced and copied to the second depth buffer 24D2 having a resolution half that of the first depth buffer 24D1. As a reduction copy method, the color of one pixel out of the four pixels in the second row and the second column of the first color buffer 24A may be copied as the color of one pixel of the second color buffer 24B. The average value of the colors of the four pixels in the first color buffer 24A may be copied as the color of one pixel in the second color buffer 24B.

  Then, as shown by A3 in FIG. 2, an effect image representing smoke is displayed in the second color buffer 24B based on the position (world coordinate system) where an explosion or a flame has occurred in the object space determined by the result of the game process. Drawn. In the example of FIG. 2, as shown in FIG. 3A, an effect object configured by rectangular polygons in which the α value of vertex data is set to α = 1.0 (opaque) is set. An effect texture that expresses smoke in which the color of smoke particles and an α value that takes a value of 0.0 to 1.0 is set for each texel is mapped to the effect object, thereby creating an effect. The image is drawn in the second color buffer 24B. Specifically, the texture for effects is set to a texel for which the smoke particle color is set, and an α value of 0.0 <α ≦ 1.0 is set for the texel for which the smoke particle color is set. Is set to an α value such that α = 0.0. In the example of FIG. 2, as shown in FIG. 3B, about 10 effect objects are set to overlap while changing the orientation, and the effect texture is mapped to each effect object. An effect image expressing natural smoke that is not uniform is drawn.

  Therefore, in the example of FIG. 2, the color of the original image and the color of about ten effect textures are synthesized by α blending. In addition, in the example of FIG. 2, when the effect texture color is combined with the color of the original image, various parameters used for light source calculation, texture expression, and the like are referred to for each pixel. Will be very heavy. However, in the example of FIG. 2, since the effect image is drawn on the original image reduced and copied to the second color buffer 24B, the processing load is higher than drawing the effect image on the original image in the first color buffer 24A. It has been greatly reduced.

  In the example of FIG. 2, when the effect image is rendered in the second color buffer 24B, the comparison result between the depth value of the effect object and the depth value of the original image stored in the second depth buffer 24D2 is used. Based on the depth test. In the example of FIG. 2, the position where the smoke is generated as a result of the game process is behind the spherical object as viewed from the virtual camera, and thus the effect object is set behind the spherical object. Therefore, as shown by A3 in FIG. 2, among the pixels of the second color buffer 24B, for the pixel corresponding to the spherical object that overlaps in front of the effect object when viewed from the virtual camera, the color of the spherical object is drawn. For pixels corresponding to an effect object that does not overlap with the sphere object when viewed from the perspective, the color of the effect image is drawn.

  In the example of FIG. 2, an effect image is extracted from the image of the second color buffer 24B, and this is doubled in accordance with the resolution of the first color buffer 24A. As shown in A4 of FIG. It is synthesized at a position (pixel) corresponding to the effect image in the color buffer 24A. In this way, in the example of FIG. 2, the effect image is combined with the original image drawn in the first color buffer 24A while reducing the processing load when drawing the effect image.

  However, in such a conventional method, the effect image synthesized with the original image of the first color buffer 24A is twice the image corresponding to the effect object extracted from the image of the second color buffer 24B. Since the image is enlarged, as shown in FIG. 4, the pixel color near the boundary between the spherical object and the effect image is drawn as if blurred. In particular, in the part surrounded by a line in FIG. 4, the color of the effect image is drawn on the pixel where the color of the object is to be drawn, and the color of the object is drawn on the pixel where the color of the effect image is to be drawn. The state that has been marked appears remarkably.

1-2-2. Next, features of the technique of this embodiment will be described. FIG. 5 is a diagram for explaining a technique employed in the image generation system of the present embodiment. In FIG. 5, as in FIG. 2, an example in which an effect image that expresses smoke is synthesized behind the black spherical object as viewed from the virtual camera will be described. First, as in B1 of FIG. 5, in the method of the present embodiment, as in the conventional method, the color of each pixel of the original image obtained by viewing the spherical object set in the object space from the virtual camera is the final display image. The depth value of each pixel of the original image is stored in a depth buffer 24D having the same resolution as the first color buffer 24A. Furthermore, in this embodiment, as shown by B1 in FIG. 5, the value of each pixel of the stencil buffer 24E having the same resolution as the first color buffer 24A is reset to zero.

  Then, as shown in B2 of FIG. 5, the color of each pixel of the original image drawn in the first color buffer 24A is reduced and copied to the second color buffer 24B having a resolution half that of the first color buffer 24A. The However, in the method of the present embodiment, unlike the conventional method, the depth value of each pixel of the original image drawn in the depth buffer 24D is not reduced and copied.

  Then, as in B3 of FIG. 5, an effect image representing smoke is drawn in the second color buffer 24B. Also in the method of the present embodiment, as in the conventional method, the effect object shown in FIG. 3A is located at the position (world coordinate system) where an explosion or a flame has occurred in the object space determined by the result of the game process. The effect image is rendered in the second color buffer 24B by mapping the effect texture to the effect object. Here, in this embodiment as well, as shown in FIG. 3B, about 10 effect objects are set to overlap each other while changing the direction, and the effect texture is mapped to each effect object, thereby uniform. An effect image that expresses natural smoke is not drawn.

  Also in the method of the present embodiment, as in the conventional method, the colors of the original image and the colors of about 10 effect textures are synthesized by α blending, and in this case, they are used for light source calculation, texture expression, and the like. Various parameters are referenced for each pixel.

  However, in the method of the present embodiment, unlike the conventional method, when the effect image is drawn in the second color buffer 24B, the depth value of the effect object and the depth of the original image stored in the second depth buffer 24D2 are used. The depth test is not performed based on the comparison result with the value. Therefore, in the example of FIG. 5, the smoke generation position determined by the game processing result is behind the spherical object as viewed from the virtual camera, but since the depth test is not performed, as shown in B <b> 3 of FIG. 5. In addition, the color of the effect image is overwritten with the color of the original image drawn in the second color buffer 24B.

  Further, in the method of the present embodiment, unlike the conventional method, a stencil image designating a pixel for drawing an effect image in the first color buffer 24A is drawn in the stencil buffer 24E as shown in B4 of FIG. Specifically, in the present embodiment, the effect object is set based on the position (world coordinate system) where smoke determined by the result of the game process is generated. The rectangular effect object is stored in the stencil buffer 24E while the depth test is performed based on the comparison result between the depth value of the original image stored in the depth buffer 24D and the depth value included in the position of the effect object. Drawn. In the present embodiment, “1” is stored for the pixel with the effect object closest to the pixel in the stencil buffer 24E, and “0” is stored for the pixel with the effect object closest to the front. As a result, as shown in B4 of FIG. 5, “1” (white) is stored for pixels other than the pixels corresponding to the spherical object among the pixels corresponding to the area where about 10 effect objects overlap, A stencil image storing “0” for a pixel is drawn.

  In the method of this embodiment, unlike the conventional method, a stencil test is performed on all the pixels of the second color buffer 24B based on the stencil image drawn as described above. For pixels that pass the stencil test, the color of the second color buffer 24B is enlarged and copied to the first color buffer 24B, as shown in B5 of FIG. In the present embodiment, for pixels in which “1” is stored in the stencil image, the color of the second color buffer 24B is drawn in the first color buffer 24A, and for pixels in which “0” is stored in the stencil image, The color of the original image in the first color buffer 24A remains without being updated.

  Therefore, according to the method of the present embodiment, when the effect image is synthesized with the original image of the first color buffer 24A, the stencil image drawn in the stencil buffer 24E having the same resolution as the first color buffer 24A is used. Since the pixel corresponding to the spherical object is masked, the color of the effect image is not drawn in the pixel where the color of the spherical object is to be drawn. Furthermore, according to the method of the present embodiment, the effect image in the second color buffer 24B is overwritten with the color of the effect image over the color of the original image drawn in the second color buffer 24B as shown in B3 of FIG. Therefore, even when the enlarged copy is made in the first color buffer 24A, the color of the spherical object is not drawn in the pixel where the color of the effect image is to be drawn.

  That is, according to the method of the present embodiment, the effect image synthesized with the original image of the first color buffer 24A is twice as large as the image corresponding to the effect object in the image of the second color buffer 24B. However, as shown in FIG. 6, the pixels near the boundary between the spherical object and the effect image are not drawn so that the colors of the pixels blur each other, and the image is degraded as compared with the conventional method. Remarkably avoided.

1-3. Processing of this Embodiment Next, an example of processing of this embodiment will be described using the flowchart of FIG. As shown in FIG. 7, the image generation system of the present embodiment first resets the values of all pixels in the stencil buffer 24E to “0” when the frame update timing arrives (Y in step S10) (step S12). ). Then, the color of the original image in the first color buffer 24A is reduced and copied to the second color buffer 24B (step S14). Then, the effect object is set at a position in the object space determined by the result of the game process, the effect texture is mapped to the effect object, and the color of the effect image is set to the second color buffer 24B without performing the depth test. (Step S16). Then, while performing a depth test based on a comparison result between the depth value of the original image in the depth buffer 24D and the depth value of the effect object, a stencil image in which the pixel closest to the effect object is “1” is converted into a stencil image. Drawing in the buffer E (step S18). Then, the color of the effect image drawn in the second color buffer 24B is drawn for the pixels for which “1” is set in the stencil image among the pixels in the first color buffer 24A (step S20).

1-4. Hardware Configuration Example Next, an example of a hardware configuration for realizing the image generation system of the present embodiment will be described with reference to FIG. Note that FIG. 8 shows only main components, and hardware (such as a memory controller and a speaker) not shown in FIG. 8 can be provided as necessary.

  The main processor 200 operates based on a program stored on the optical disk 272 (an information storage medium such as a CD, DVD, or Blu-ray disc), a program transferred via the communication interface 280, or a program stored on the hard disk 260. The main memory 240 accessible via the internal bus b4 is used as a work area (work area) to execute various processes such as game processing, image processing, and sound processing.

  The main processor 200 includes a single processor 210 and a plurality of vector processors 212. The processor 210 executes various processes such as OS execution, hardware resource management, game processing, and operation management of the vector processor 212. The vector processor 212 is a processor specialized in vector operations, and mainly executes processes such as geometry processing and codec processing of image data and sound data.

  The drawing processor 220 is configured to be accessible to the video memory 230 via the internal bus b1 (first internal bus). The drawing processor 220 also includes an internal bus b2 (second internal bus) that connects the drawing processor 220 and the main processor 200, a bus b3 inside the main processor 200, and an internal bus b4 that connects the main processor 200 and the main memory 240. The main memory 240 can be accessed via the. That is, the drawing processor 220 can use the video memory 230 and the main memory 240 as a rendering target.

  The drawing processor 220 performs geometric processing such as coordinate transformation, perspective transformation, light source calculation, and curved surface generation, and 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 200 instructs the rendering processor 220 to perform the processing.

  The drawing processor 220 executes image rendering processing of an object after geometry processing (an object composed of a primitive surface such as a polygon or a curved surface) at high speed. In the multi-pass rendering process, the drawing processor 220 performs the hidden surface removal using the Z buffer 234 and the like based on the drawing data (vertex data and other parameters) and the like, and displays the image in the video memory 230 or the main memory. Render to one of 240 memories. Then, a process of rendering a new image in the other memory based on the image stored in one of the video memory 230 and the main memory 240 is performed as many times as necessary. The rendering processor 220 can perform filter processing (effect processing) such as glare filter processing, motion blur processing, depth of field processing, and fog processing as the multi-pass rendering processing.

  When the image is rendered in the frame buffer 232 provided in the video memory 230 in the final rendering pass, the image is output to the display 250. When an image is rendered in the main memory 240 in the final rendering pass, the image is copied (written) to the frame buffer 232 and output to the display 250.

  The hard disk 260 stores system programs, save data, personal data, and the like.

  The optical drive 270 drives an optical disk 272 (information storage medium) that stores programs, image data, sound data, and the like, and enables access to these programs and data.

  The communication interface 280 is an interface for performing data transfer with the outside via a network. In this case, as the network connected to the communication interface 280, a communication line (analog telephone line, ISDN), a high-speed serial bus, and 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.

  As described above, the image generation system (computer) according to the present embodiment can access the video memory 230 via the internal bus b1 (first internal bus) and also uses the internal bus b2 (second internal bus). The drawing processor 220 is accessible to the main memory 240 via the optical disk 272 (an example of an information storage medium) or the hard disk 260 (an example of an information storage medium). Various shader processes are executed according to the shader program.

  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 the processors 200, 220, etc., which are hardware, and passes data if necessary. Each processor 200, 220, etc., implements each unit of the present invention based on the instruction and the passed data.

2. Second Embodiment 2-1. Configuration Next, an image generation system (game system) according to a second embodiment will be described. In the following, the configuration of functional blocks in the image generation system of the second embodiment will be described with reference to FIG. 1, but the same points as the configuration of functional blocks in the image generation system of the first embodiment will be described in detail. The main differences will be described.

  In the present embodiment, unlike the first embodiment, the depth buffer 24 in FIG. 1 includes a first depth buffer 24D1 having the same resolution as the first color buffer 24A and a second depth having the same resolution as the second color buffer 24B. And a buffer 24D2.

  In the present embodiment, the effect processing unit 124 first performs a process of drawing (reducing and copying) the color of each pixel constituting the original image drawn in the first color buffer 24A in the second color buffer 24B. The depth value of each pixel constituting the original image drawn in the 1-depth buffer 24D1 is drawn (reduced copy) in the second depth buffer 24D2 (reduced buffer).

  Furthermore, in the present embodiment, unlike the first embodiment, the effect processing unit 124 performs a depth test when performing a process of drawing an effect image in the second color buffer. Specifically, the effect processing unit 124 uses a rectangular polygon in which the alpha value of the vertex data is set to be opaque at a position (world coordinate system) where an explosion or a flame has occurred in the object space determined by the game processing result. Set the configured effect object. Then, the effect processing unit 124 performs the above-described geometry processing on the effect object, and maps the effect texture that expresses flame, smoke, flash, or the like to the effect object, while the original image of the second depth buffer 24D2 is mapped. While performing a depth test based on a comparison result between the depth value and the depth value of the effect object, a process of rendering the color of the effect image in the second color buffer 24B is performed.

2-2. Next, features of the technique of this embodiment will be described. In the image generation system of the first embodiment described above, since the color of the effect image is overwritten on the color of the original image drawn in the second color buffer 24B as shown in B3 of FIG. When the spherical object, the first effect image set in front of the spherical object as viewed from the virtual camera, and the second effect image set in the back of the spherical object as viewed from the virtual camera overlap, Inconvenient cases may occur in which the front-and-rear relationship is not accurately drawn. Therefore, in the image generation system of this embodiment, such inconvenience is prevented from occurring.

  FIG. 9 is a diagram for explaining a technique employed in the image generation system of the present embodiment. In FIG. 9, as in FIG. 5, an example in which an effect image that expresses smoke is synthesized behind the black spherical object as viewed from the virtual camera will be described. First, as in C1 of FIG. 9, in the method of the present embodiment, the color of each pixel of the original image obtained by viewing the spherical object set in the object space from the virtual camera is the same as the method of the first embodiment. The depth value of each pixel of the original image is stored in the first depth buffer 24D1 having the same resolution as that of the first color buffer 24A. Then, as indicated by C1 in FIG. 9, the value of each pixel of the stencil buffer 24E having the same resolution as the first color buffer 24A is reset to zero.

  Then, as shown in C2 of FIG. 9, the color of each pixel of the original image drawn in the first color buffer 24A is reduced and copied to the second color buffer 24B having a resolution twice that of the first color buffer 24A. The In the method of the present embodiment, unlike the method of the first embodiment, the depth value of each pixel of the original image drawn in the first depth buffer 24D1 has a resolution twice that of the first depth buffer 24D1. The reduced copy is made to the second depth buffer 24D2.

  Then, as in C3 of FIG. 9, an effect image representing smoke is drawn in the second color buffer 24B. In the method of the present embodiment, as in the method of the first embodiment, the effect object shown in FIG. 3A is set, and the effect image is mapped to the effect object by mapping the effect texture. The image is drawn in the two-color buffer 24B. Then, as shown in FIG. 3B, about 10 effect objects are overlapped while changing the direction, and the effect texture is mapped to each effect object. The effect image that expresses is drawn.

  Also in the method of the present embodiment, as in the method of the first embodiment, the colors of the original image and about ten effect texture colors are synthesized by α blending. In this case, light source calculation, texture expression, etc. Various parameters used in the are referred to for each pixel.

  However, unlike the method of the first embodiment, the method of the present embodiment differs from the method of the first embodiment when the effect image is drawn in the second color buffer 24B, and the depth value of the effect object and the original value stored in the second depth buffer 24D2. A depth test is performed based on the comparison result with the depth value of the image. In the example of FIG. 9, the position where smoke is generated as a result of the game process is behind the spherical object as viewed from the virtual camera, and therefore the effect object is set behind the spherical object. Therefore, as shown in C3 of FIG. 9, among the pixels of the second color buffer 24B, for the pixel corresponding to the spherical object that overlaps in front of the effect object when viewed from the virtual camera, the color of the spherical object is drawn. For pixels corresponding to an effect object that does not overlap with the sphere object when viewed from the perspective, the color of the effect image is drawn.

  In the method of the present embodiment, as in the method of the first embodiment, a stencil image that designates a pixel for drawing an effect image in the first color buffer 24A is drawn in the stencil buffer 24E, as in C4 of FIG. . More specifically, in the method of the present embodiment as well, as in the method of the first embodiment, the effect object is set based on the position where smoke determined by the game processing result is generated. Then, a rectangular effect object is drawn in the stencil buffer 24E while performing a depth test based on a comparison result between the depth value of the original image stored in the depth buffer 24D and the depth value included in the position of the effect object. Is done.

  In the method of this embodiment, as in the method of the first embodiment, the stencil test is performed on all the pixels in the second color buffer 24B based on the stencil image drawn as described above. As for C5 in FIG. 9, for the pixel in which “1” is stored in the stencil image, the color of the second color buffer 24B is drawn in the first color buffer 24A, and “0” is stored in the stencil image. For the remaining pixels, the color of the original image in the first color buffer 24A remains without being updated.

  Therefore, according to the method of the present embodiment, when the effect image is synthesized with the original image of the first color buffer 24A, the stencil image drawn in the stencil buffer 24E having the same resolution as the first color buffer 24A is used. Since the pixel corresponding to the spherical object is masked, the color of the effect image is not drawn in the pixel where the color of the spherical object is to be drawn. On the other hand, the effect image of the second color buffer 24B in the present embodiment is drawn after the context is determined by the depth test as shown by C3 in FIG. 9, and therefore when the enlarged image is copied to the first color buffer 24A, The color of the sphere object may be drawn at the pixel where the color of the effect image is to be drawn. However, according to the method of the present embodiment, the effect image of the second color buffer 24B has been determined in the depth test by the depth test, so that the first effect image and the second effect image are the specific object as viewed from the virtual camera. Even if it is set so as to overlap the specific object in the front and back, there is no inconvenience that these front-rear relations are not drawn accurately.

  That is, according to the method of the present embodiment, a plurality of effect images can be set regardless of the positional relationship with the spherical object, and as shown in FIG. The image is not drawn so that the color of the image is blurred with respect to the color of the spherical object, and the deterioration of the image is sufficiently avoided as compared with the conventional method.

2-3. Processing of this Embodiment Next, an example of processing of this embodiment will be described using the flowchart of FIG. As shown in FIG. 11, in the image generation system of the present embodiment, first, when the frame update timing arrives (Y in step S110), the values of all pixels in the stencil buffer 24E are reset to “0” (step S112). ). Then, the original color of the first color buffer 24A is reduced and copied to the second color buffer 24B, and the depth value of the original image of the first depth buffer 24D1 is copied to the second depth buffer 24D2 (step S114). Then, the effect object is set at a position in the object space determined by the result of the game process, and the depth value of the original image in the second depth buffer 24D2 and the effect object are mapped while the effect texture is mapped to the effect object. The color of the effect image is drawn in the second color buffer 24B while performing the depth test based on the comparison result with the depth value (step S116). Then, based on the comparison result between the depth value of the original image in the first depth buffer 24D1 and the depth value of the effect object, a stencil image in which the pixel closest to the effect object is “1” is stored in the stencil buffer E. Drawing is performed (step S118). Then, the color of the effect image drawn in the second color buffer 24B is drawn with respect to the pixel for which “1” is set in the stencil image among the pixels in the first color buffer 24A (step S120).

3. Modifications The present invention is not limited to that described in the above embodiment, and various modifications can be made. For example, terms cited as broad or synonymous terms in the description in the specification or drawings can be replaced with broad or synonymous terms in other descriptions in the specification or drawings. Further, the glare filter technique is not limited to that described in the present embodiment, and techniques equivalent to these techniques are also included in the scope of the present invention.

  In the above-described embodiment, the effect processing unit 124 has been described with an example in which the effect processing is performed once for one frame. However, the effect processing unit 124 may perform the effect processing a plurality of times for one frame. For example, a first effect process that performs effect processing on a first effect image that is set in front of a specific object when viewed from the virtual camera, and a second effect image that is set behind the specific object when viewed from the virtual camera. You may make it perform the 2nd effect process which performs an effect process. In this case, the effect processing unit 124 reduces and copies the original image drawn in the first color buffer 24A to the second color buffer 24B, and also applies it to the third color buffer having the same resolution as the second color buffer 24B. The second color buffer 24B may be used as a rendering target for the effect image in the first effect processing, and the third color buffer may be used as the rendering target for the effect image in the second effect processing.

  In this way, even if the first effect image and the second effect image are set so as to overlap the specific object before and behind the specific object when viewed from the virtual camera, the first effect image for the first effect image is set. When the processing and the second effect processing for the second effect image are performed, the depth value of the original image and the depth value of the effect image when performing the processing of rendering the effect image in the second color buffer and the third color buffer. Based on the above, it is possible to avoid the deterioration of the image by the stencil image while accurately drawing these front-rear relationships without performing the depth test.

  In the above-described embodiment, the example has been described in which the effect processing unit 124 performs the process of drawing the shape of the effect object visible from the virtual camera as the stencil image in the stencil buffer 24E. Based on the texture, a process of drawing the stencil image in the stencil buffer 24E may be performed. Specifically, the effect processing unit 124 maps the effect texture to the effect object that can be seen from the virtual camera, and the pixel in which the color is set in the area to which the effect texture is mapped, that is, the pixel whose α value is larger than 0. In this case, “1” is stored in the pixel and “0” is stored in the pixel having the α value of 0, so that the stencil image may be drawn in the stencil buffer 24E. In this way, it is possible to further avoid image degradation by drawing a detailed stencil image corresponding to the texture for effect.

  Further, in the above-described embodiment, an example in which the effect processing unit 124 performs effect processing for synthesizing an effect image expressing flame, smoke, flash, or the like with an original image when an event such as an explosion or a fire occurs. As described above, when a character uses a specific technique, an effect image representing an aura may be synthesized behind the character, or when the character is attacked by the opponent character, You may make it synthesize | combine the effect image to represent.

  In addition, when the character attacks the opponent character or receives an attack from the opponent character, the effect processing unit 124 determines whether the attack hits the opponent character or the character. Thus, the position of the effect object may be set to be behind the specific object when viewed from the virtual camera, and the attack direction determined based on the direction information input to the operation unit 10 May be set so that the position of the effect object is behind the specific object when viewed from the virtual camera.

  In addition, the position and movement range of the effect object are set not only to the representative point indicating the character position but also to an area farther from the virtual camera than the end of the character's hand or foot. Also good. For example, a bounding volume that includes the range of movement of the character's edge is set for the character, a hit check is performed between the bounding volume and the effect object, and the position of the effect object is viewed from the virtual camera. You may make it set so that it may become behind.

  Further, the first color buffer 24A in which the original image is drawn and the first color buffer 24A in which the effect image is combined may use the physically same buffer or different buffers.

  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 1st Embodiment. Explanatory drawing of the method of the conventional image generation system. Explanatory drawing of the method of the conventional image generation system. Explanatory drawing of the method of the conventional image generation system. Explanatory drawing of the method of 1st Embodiment. The figure which shows an example of the image produced | generated by 1st Embodiment. The flowchart which shows the flow of a process of 1st Embodiment. 1 is a hardware configuration example of an image generation system according to a first embodiment. Explanatory drawing of the method of 2nd Embodiment. The figure which shows an example of the image produced | generated by 2nd Embodiment. The flowchart which shows the flow of a process of 2nd Embodiment.

Explanation of symbols

10 operation unit, 20 storage unit, 22 main memory,
22A object data storage unit, 22B frame buffer,
24 video memory, 24A first color buffer, 24B second color buffer,
24C texture storage unit, 24D depth buffer, 30 information storage medium,
40 portable information storage device, 50 display unit, 60 sound output unit, 70 communication unit 100 processing unit, 110 object space setting unit, 112 movement / motion processing unit,
114 virtual camera control unit, 120 drawing unit, 122 original image drawing unit,
124 effect processing unit, 130 sound generation unit

Claims (8)

A program for generating an image,
An original image drawing unit that performs processing of drawing an original image obtained by viewing an object set in the object space from a virtual camera in the first color buffer;
Causing the computer to function as an effect processing unit that performs effect processing for combining the original image and an effect image for adjusting the color of the original image;
The effect processing unit as the effect processing,
Processing to draw the original image drawn in the first color buffer in a second color buffer having a resolution lower than that of the first color buffer;
Drawing the effect image in the second color buffer;
Based on the depth value of the original image and the depth value of the effect image, a stencil image designating a pixel for drawing the effect image drawn in the second color buffer has a resolution higher than that of the second color buffer. Drawing in a high stencil buffer;
Processing to draw the effect image drawn in the second color buffer in the first color buffer based on the stencil image;
The program characterized by performing. In claim 1,
The effect processing unit
A program for performing a process of setting the position of the effect image behind the specific object as viewed from the virtual camera. In claim 1,
The effect processing unit
A program for performing a process of drawing the effect image in the second color buffer based on a depth value of the original image and a depth value of the effect image. In claim 1,
The effect processing unit
A first effect process for performing the effect process on a first effect image set in front of the specific object as viewed from the virtual camera, and a second effect set in the back of the specific object as viewed from the virtual camera. A program for performing a second effect process for performing the effect process on an image. In any one of Claims 1-4,
The effect processing unit
Mapping the effect texture to the effect object to render the effect image in the second color buffer;
A program for performing a process of drawing the stencil image in the stencil buffer based on a depth value of the effect object. In claim 5,
The effect processing unit
A program for performing a process of drawing the stencil image in the stencil buffer based on the shape of the effect object. In claim 5,
The effect processing unit
A program for performing a process of drawing the stencil image in the stencil buffer based on the effect texture. An image generation system for generating an image,
An original image drawing unit that performs processing of drawing an original image obtained by viewing an object set in the object space from a virtual camera in the first color buffer;
An effect processing unit that performs effect processing for combining the original image and an effect image for adjusting the color of the original image;
The effect processing unit as the effect processing,
Processing to draw the original image drawn in the first color buffer in a second color buffer having a resolution lower than that of the first color buffer;
Drawing the effect image in the second color buffer;
Processing to draw a stencil image for designating pixels for drawing the effect image in a stencil buffer having a resolution higher than that of the second color buffer based on the depth value of the original image and the depth value of the effect image;
Processing to draw the effect image drawn in the second color buffer in the first color buffer based on the stencil image;
The image generation system characterized by performing.