JP2007141079A - Program, information storage medium, and image generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a program, an information storage medium and an image generation system capable of attaining real environmental mapping with a reduced resource. <P>SOLUTION: This image generation system includes a tetrahedral environmental texture generating part, a texture storage part secured with a texture area formed by triangular areas TR1, TR2, TR3, TR4, and a texture mapping part. The tetrahedral environmental texture generating part sets sight line directions of a virtual camera along directions D1, D2, D3, D4 to execute lettering processing, and draws images IM1, IM2, IM3, IM4 on the triangular areas TR1, TR2, TR3, TR4 in the texture area to generate a tetrahedral environmental texture in the texture area formed by the areas TR1, TR2, TR3, TR4. <P>COPYRIGHT: (C)2007,JPO&INPIT

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 objects such as cars and characters are arranged and set is known. It is very popular for experiencing so-called virtual reality. In such an image generation system, there is a problem of generating a more realistic image in order to improve virtual reality. One method for solving such a problem is a method called environment mapping. Are known.

  Among these environment mappings, dynamic environment mapping dynamically (real-time) generates an environment texture that represents the environment around the object, and maps the generated environment texture to the object, thereby reflecting the environment on the object. Express.

As environment mapping, tetrahedral environment mapping, cube environment mapping, and the like are known. Cube environment mapping is often supported by hardware, but tetrahedral environment mapping is often not supported by hardware. Therefore, how to realize realistic environment mapping with limited resources such as memory becomes a technical issue.
JP 2001-70633 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a program, an information storage medium, and an image generation system capable of realizing a real environment mapping with few resources. .

  The present invention is an image generation system that generates an image, and includes a tetrahedral environment texture generation unit that generates a tetrahedral environment texture, a first triangular area, and a second that shares an edge with the first triangular area. A texture region formed by the triangular region, the third triangular region sharing the side with the second triangular region, and the fourth triangular region sharing the side with the third triangular region is secured. A texture storage unit, and a texture mapping unit that performs a texture mapping process on the object, wherein the tetrahedral environment texture generation unit changes the line-of-sight direction of the virtual camera in the first, second, third, and fourth directions. The first, second, third, and fourth rendering processes are set and the first, second, third, and fourth rendering processes are used to perform the first, second, third, and fourth rendering processes. The tech A tetrahedral environment is formed in the texture region formed by the first, second, third, and fourth triangular regions by drawing in the first, second, third, and fourth triangular regions of the tea region. The present invention relates to an image generation system for generating a texture. 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 first, second, third, and fourth images generated by setting the viewing direction of the virtual camera to the first, second, third, and fourth directions are the first of the texture regions. , Drawn in the second, third and fourth triangular regions. Then, a tetrahedral environment texture is generated in the texture region formed by the first, second, third, and fourth triangular regions, and environment texture mapping is performed. If the tetrahedral environment texture is generated in the texture area in this way, the used storage capacity of the texture storage unit can be saved, so that realistic environment mapping can be realized with a small amount of resources.

  In the present invention, the first, second, third, and fourth triangular regions are right-angled triangular regions, and the texture storage unit includes the first, second, third, and fourth triangular regions. A rectangular texture region to be formed may be secured.

  As described above, if the secured texture area is rectangular, the texture storage area can be used more efficiently.

  In the image generation system, the program, and the information storage medium according to the present invention, the tetrahedral environment texture generation unit has a triangular area shape of the first, second, third, and fourth images. The tetrahedral environment texture may be generated by performing the first, second, third, and fourth rendering processes so as to be transformed into the shapes of the second, third, and fourth triangular regions. Good.

  The deformation process in this case can be realized by including a matrix for realizing the deformation in a matrix used for the rendering process.

  In the image generation system, the program, and the information storage medium according to the present invention, the tetrahedral environment texture generation unit includes a boundary between the first and second triangular regions, a boundary between the second and third triangular regions, The tetrahedral environment texture may be generated by performing the first, second, third, and fourth rendering processes so that the images are continuous at the boundary between the third and fourth triangular regions. .

  In this way, the image of the boundary between the triangular regions becomes continuous in the tetrahedral environment texture. Accordingly, when a given process is performed on the tetrahedral environment texture, a correct processing result can be obtained, and the quality of the image can be improved.

  The image generation system, the program, and the information storage medium according to the present invention may include an effect processing unit that performs an effect process on the tetrahedral environment texture generated in the rectangular texture region.

  By performing such effect processing, high-quality and realistic environment mapping can be realized. In the present invention, the image of the boundary between the triangular regions is continuous in the tetrahedral environment texture. Therefore, even when such effect processing is performed, a correct processing result can be obtained, and the quality of the image can be improved.

  The image generation system, program, and information storage medium according to the present invention include a cube environment texture generation unit that generates a cube environment texture based on the generated tetrahedral environment texture (the computer functions as the cube environment texture generation unit). The texture mapping unit may perform a texture mapping process based on the generated cube environment texture.

  In this way, for example, in an image generation system that supports cube environment mapping, real environment mapping can be realized with a small processing load.

  In the image generation system, the program, and the information storage medium according to the present invention, the cube environment texture generation unit includes the first, second, and second drawn in the first, second, third, and fourth triangular regions. The cube environment texture may be generated using a tetrahedral object in which the third and fourth triangular images are mapped to the first, second, third and fourth primitive surfaces.

  In this way, it is possible to realize cube environment mapping using a tetrahedral environment texture only by preparing a tetrahedral object.

  In the image generation system, the program, and the information storage medium according to the present invention, the cube environment texture generation unit sets the line-of-sight direction of the virtual camera set in the tetrahedral object to the fifth, sixth, seventh, The cube environment texture may be generated by performing the fifth, sixth, seventh, eighth, ninth, and tenth rendering processes by setting the eighth, ninth, and tenth directions. .

  In this way, the cube environment texture can be generated with a simple process.

  In the image generation system, the program, and the information storage medium according to the present invention, the texture mapping unit includes the first, second, third, and third drawn in the first, second, third, and fourth triangular regions. The fourth triangular image may be subjected to environment mapping with respect to the object using a tetrahedral object mapped to the first, second, third, and fourth primitive planes.

  In this way, various environment mappings such as sphere environment mapping can be realized.

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

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

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

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

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

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

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

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

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

  The object space setting unit 110 includes various objects (primitive surfaces such as polygons, free-form surfaces, and subdivision surfaces) representing display objects such as cars, trains, characters, buildings, stadiums, trees, pillars, walls, and maps (terrain). The object is placed and set in the object space. In other words, the position and rotation angle of the object in the world coordinate system (synonymous with direction and direction) are determined, and the rotation angle (rotation angle around the X, Y, and Z axes) is determined at that position (X, Y, Z). Arrange objects. Specifically, the model data storage unit 176 of the storage unit 170 stores model data of a moving object (car), a fixed object (building), and a background object (map, celestial sphere). Then, the object space setting unit 110 performs an object setting (arrangement) process in the object space using the model data.

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

  The virtual camera control unit 114 performs a virtual camera (viewpoint) control process for generating an image viewed from a given (arbitrary) viewpoint in the object space. Specifically, 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 (eg, character, ball, car) is photographed from behind using a virtual camera, the position or rotation angle of the virtual camera (the direction of the virtual camera is set so that the virtual camera follows changes in the position or rotation of the object. ) To control. In this case, the virtual camera can be controlled based on information such as the position, rotation angle, or speed of the object obtained by the movement / motion processing unit 112. Alternatively, the virtual camera may be controlled to rotate at a predetermined rotation angle or to move along a predetermined movement path. In this case, the virtual camera is controlled based on the virtual camera data for specifying the position (movement path) or rotation angle of the virtual camera. When there are a plurality of virtual cameras (viewpoints), the above control process is performed for each virtual camera.

  The 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, model data including vertex data (vertex position coordinates, texture coordinates, color data, normal vector, α value, etc.) of each vertex of the model (object) is first input. Based on the vertex data included in the input model data, vertex processing (shading by a vertex shader) is performed. 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. 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 final drawing color of the constituent pixels is determined, and the drawing color of the perspective-transformed model is output (drawn) to the drawing buffer 174 (a buffer capable of storing image information in units of pixels; VRAM, rendering target). That is, in pixel processing, per-pixel processing for setting or changing image information (color, normal, luminance, α value, etc.) in units of pixels is performed. As a result, an image that can be seen from the virtual camera (given viewpoint) in the object space is generated.

  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, hidden surface removal processing, α blending, 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, model 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 storage unit 170. .

  As the hidden surface removal processing, hidden surface removal processing can be performed by a Z buffer method (depth comparison method, Z test) using a Z buffer (depth buffer) in which Z values (depth information) of drawing pixels are stored. . That is, when drawing pixels corresponding to the primitive of the object are drawn, the Z value stored in the Z buffer is referred to. Then, the Z value of the referenced Z buffer is compared with the Z value at the drawing pixel of the primitive, and the Z value at the drawing pixel is a Z value (for example, a small Z value) on the near side when viewed from the virtual camera. In some cases, the drawing process of the drawing pixel is performed and the Z value of the Z buffer is updated to a new Z value.

  α blending (α synthesis) is a translucent synthesis process (usually α blending, addition α blending, subtraction α blending, or the like) based on an α value (A value).

  The α value is information that can be stored in association with each pixel (texel, dot), for example, plus alpha information other than color information. The α value can be used as mask information, translucency (equivalent to transparency and opacity), bump information, and the like.

  The drawing unit 120 includes a tetrahedral environment texture generation unit 122, an effect processing unit 124, a cube environment texture generation unit 126, and a texture mapping unit 128. Note that some of these may be omitted.

  The tetrahedral environment texture generation unit 122 performs a tetrahedral environment texture generation process. Specifically, for example, a rectangular texture area is secured in the texture storage unit 178. This rectangular texture area (texture area in a broad sense) shares a long side (side in a broad sense) with the first right triangle area (first triangle area in a broad sense) and the first right triangle area (in a broad sense). The second right triangle region (second triangle region in a broad sense) and the third right triangle region (second in a broad sense) that share a short side (side in a broad sense) with the second right triangle region. 3 triangle regions) and a fourth right triangle region (fourth triangle region in a broad sense) sharing a long side (side) with the third right triangle region. Then, the tetrahedral environment texture generation unit 122 performs the first, second, third, and fourth rendering processes by setting the viewing direction of the virtual camera to the first, second, third, and fourth directions. Then, an image that is visible when the viewing direction of the virtual camera is in the first, second, third, and fourth directions is generated. Specifically, for example, the shape of the triangular area (regular triangular area) of the first, second, third, and fourth images is the first, second, third, and fourth right triangle areas (first, second, The first, second, third, and fourth rendering processes are performed so as to be transformed into the shape of the second, third, and fourth triangular regions. This deformation of the shape can be realized by a matrix used in the rendering process. The tetrahedral environment texture generation unit 122 also includes the boundaries (long sides) of the first and second right triangle regions, the boundaries (short sides) of the second and third right triangle regions, and the third and fourth right triangles. The first, second, third, and fourth rendering processes are performed so that the images (pixel images) are continuous at the boundary (long side) of the region. The order of the first, second, third, and fourth rendering processes is arbitrary.

  Then, through these first, second, third, and fourth rendering processes, the first, second, third, and fourth images (triangle images and equilateral triangle images) are converted into texture regions of the texture storage unit 178. It is drawn in the first, second, third and fourth right triangle regions. As a result, an environment texture for tetrahedral environment mapping is generated (drawn) in a rectangular texture region (texture storage unit 178) constituted by the first, second, third, and fourth right triangle regions.

  The effect (blurring) processing unit 124 performs effect processing on the tetrahedral environment texture generated in the rectangular texture region of the texture storage unit 178. The effect processing in this case includes various filter processing such as blur processing and edge extraction processing. The blurring processing includes pixel value averaging processing, pixel replacement processing, and the like.

  The cube environment texture generation unit 126 (texture conversion unit) performs a cube environment texture generation process based on the tetrahedral environment texture generated by the tetrahedral environment texture generation unit 122. Specifically, the first, second, third, and fourth right triangle images (first, second, and second in a broad sense) drawn in the first, second, third, and fourth right triangle regions. 3 and 4 triangular images) are prepared as tetrahedral objects to be mapped to the first, second, third and fourth primitive surfaces (polygons). That is, a tetrahedral object in which texture coordinates are set so that the first, second, third, and fourth right triangle images are mapped to the first, second, third, and fourth surfaces is prepared. The data of this tetrahedral object can be stored in the model data storage unit 176. The cube environment texture generation unit 126 generates a cube environment texture by performing a rendering process using the tetrahedral object. Specifically, the line-of-sight direction of the virtual camera arranged in the tetrahedral object is set to the fifth, sixth, seventh, eighth, ninth, and tenth directions (front, right, rear, left, down, The cube environment texture is generated by performing the fifth, sixth, seventh, eighth, ninth, and tenth rendering processing with the upward setting.

  The texture mapping unit 128 performs texture mapping processing on the object (model). Here, the texture mapping process is a process for mapping the texture (texel value) stored in the texture storage unit 178 of the storage unit 170 to the object. Specifically, texture (surface property such as color and α value) data is read from the texture storage unit 178 using texture coordinates or the like set (given) to the vertex of the object. Then, a texture that is a two-dimensional image is mapped to an object. In this case, it is possible to perform processing for associating pixels with texels, bilinear interpolation or the like as texel interpolation.

  In this embodiment, the texture mapping unit 128 performs processing for mapping the environment texture generated by the tetrahedral environment texture generation unit 122, the cube environment texture generation unit 124, and the like to the object. In this case, if necessary, texture coordinate calculation processing such as converting the coordinates of the normal vector set in the object into texture coordinates is performed.

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

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

2. 2. Method of this Embodiment 2.1 Generation of Tetrahedral Environment Texture In this embodiment, as shown in FIG. Are dynamically generated as a tetrahedral environment texture in real time.

  Specifically, as shown in FIG. 3A, the line-of-sight direction of the virtual camera VC set at the center point CPC of the virtual cube object OBC is set to the D1 direction. The direction D1 is a direction from the center point CPC of the cubic object OBC toward the vertex VC1. In FIG. 2, this corresponds to directing the line-of-sight direction of the virtual camera VC set at the center point CPC of the tetrahedral object OBT to the center point (center of gravity) of the regular triangle surface SF1 constituting the OBT. In this case, the vector in the direction D1, which is the line-of-sight direction of the virtual camera VC, and the surface SF1 are orthogonal to each other.

  Then, the first image IM1 of FIG. 4A is generated by the rendering process (first rendering process) of the image of the surrounding environment seen from the virtual camera VC in which the line-of-sight direction is set to the D1 direction. The For example, the virtual camera VC is set at the position of the representative point (for example, the center point) of the moving object. The line-of-sight direction of the virtual camera VC is set to the D1 direction, and an image of the environment (background of sky, building, etc.) around the moving object (car, train) is generated as the first image IM1.

  In the present embodiment, the first image IM1 is drawn in the first right triangle region TR1 as shown in FIG. That is, the view port of the virtual camera VC is set in the areas TR1 and TR2, and only the TR1 out of TR1 and TR2 is set as the drawing area and the image IM1 is drawn.

  Here, the texture storage unit 178 has a rectangular (rectangular, square) texture region RER as a dynamic environment texture generation region. The rectangular texture region RER includes a first right triangle region TR1, a second right triangle region TR2 sharing TR1 and its long side LS1, and a third right triangle region TR3 sharing TR2 and its short side SS1. And TR4 and a fourth right triangle region TR4 sharing its long side LS2. The shapes of the regions TR1, TR2, TR3, and TR4 may be isosceles right triangles, right triangles that are not isosceles, or triangles other than right triangles.

  The rendering process of the image IM1 into the right triangle region TR1 is realized by the method shown in FIG. That is, the rendering process is performed so that the shape of the triangular area (surface SF1 in FIG. 2) of the image IM1 is transformed into the shape of the right-angled triangular area TR1. Specifically, the transformation process is performed so that the vertices VA, VB, and VC of the triangle area (regular triangle area) coincide with the vertices VTA, VTB, and VTC of the right triangle area TR1. By doing so, the image of the triangular area of the image IM1 is deformed and drawn in the right triangle area TR1.

  Next, as shown in FIG. 3B, the line-of-sight direction of the virtual camera VC is set to a second direction D2 that is a direction from the center point CPC of the cube object OBC to the vertex VC8. This corresponds to directing the visual line direction of the virtual camera VC in FIG. 2 to the center point (center of gravity) of the regular triangular surface SF2 constituting the tetrahedral object OBT. In this case, the vector in the D2 direction of the virtual camera VC and the surface SF2 are orthogonal to each other. The angle θ1 formed by the first direction D1 and the second direction D2 is θ1 = arctan (−1/3).

  With the rendering process (second rendering process) of the image of the surrounding environment seen from the virtual camera VC in which the line-of-sight direction is set to the D2 direction, the second image IM2 is the second image IM2 as illustrated in FIG. Two right triangle regions TR2 are drawn. That is, only the TR2 of the regions TR1 and TR2 is set as the drawing region, and the image IM2 is drawn. In this case, the rendering process of the image IM2 to the right triangle region TR2 is realized by the same method as in FIG.

  Next, as shown in FIG. 3C, the line-of-sight direction of the virtual camera VC is set to a third direction D3 that is a direction from the center point CPC of the cube object OBC toward the vertex VC6. This corresponds to directing the viewing direction of the virtual camera VC in FIG. 2 to the center point (center of gravity) of the regular triangular surface SF3 constituting the tetrahedral object OBT. In this case, the vector in the D3 direction of the virtual camera VC and the surface SF3 are orthogonal to each other. The angle θ2 formed by the second direction D2 and the third direction D3 is θ2 = arctan (−1/3).

  With the rendering process (third rendering process) of the image of the surrounding environment seen from the virtual camera VC in which the line-of-sight direction is set to the D3 direction, as shown in FIG. 3 is drawn in a right triangle region TR3. That is, the view port of the virtual camera VC is switched from the TR1 and TR2 areas to the TR3 and TR4 areas, and only TR3 of TR3 and TR4 is set as the drawing area and the image IM3 is drawn. In this case, the rendering process of the image IM3 to the right triangle region TR3 is realized by the same method as in FIG.

  Next, as shown in FIG. 3D, the line-of-sight direction of the virtual camera VC is set to a fourth direction D4 that is a direction from the center point CPC of the cube object OBC to the vertex VC3. This is equivalent to directing the direction of the line of sight of the virtual camera VC in FIG. 2 to the center point (center of gravity) of the regular triangular surface SF4 constituting the tetrahedral object OBT. In this case, the vector in the D4 direction of the virtual camera VC and the surface SF4 are orthogonal to each other. The angle θ3 formed by the third direction D3 and the fourth direction D4 is θ3 = arctan (−1/3).

  With the rendering process (fourth rendering process) of the image of the surrounding environment seen from the virtual camera VC in which the line-of-sight direction is set to the D4 direction, as shown in FIG. It is drawn in four right triangle regions TR4. In this case, the rendering process of the image IM4 to the right triangle region TR4 is realized by the same method as in FIG.

  FIG. 6 shows an example of a tetrahedral environment texture generated by this embodiment. As shown in FIG. 6, in this embodiment, tetrahedral environment textures are stored in a rectangular texture area in a compact manner. Therefore, the storage capacity of the texture storage unit can be saved, and realistic environment mapping can be realized with few resources.

  In addition, if an attempt is made to dynamically generate a cube environment texture in real time, rendering processing of an environment image with a heavy processing load is required six times. On the other hand, according to the present embodiment, the environment image rendering process only needs to be performed four times, so that the processing load can be reduced.

  Further, for example, in the method of the comparative example shown in FIG. 5B, the deformation process to the right triangle shape as shown in FIG. 5A is not performed. For this reason, the texture area in which the tetrahedral environment texture is written becomes large, and the used storage capacity of the texture storage unit is compressed as compared with the method of the present embodiment shown in FIGS.

  Further, in the method of the comparative example in FIG. 5B, the boundary BL2 and BL3 of the triangular region, BL4 and BL5, and BL6 and BL7 do not match. Therefore, there is a problem that it is difficult to perform effect processing such as blurring processing on the tetrahedral environment texture. For example, in FIG. 5C, a blurring process is performed in which the color information of the pixel PX is determined based on the color information (pixel information in a broad sense) of surrounding pixels PXA, PXB, PXC, and PXD. Specifically, a blurring process is performed in which the color information of the pixel PX is obtained based on the average value of the color information of PXA, PXB, PXC, and PXD.

  In the comparative example of FIG. 5B, since the boundary of the triangular region does not match, when such blurring processing is performed, the pixels PXB and PXC are not pixels of the adjacent triangular region, and therefore the result of the blurring processing is The result is not correct.

  On the other hand, in this embodiment, as indicated by A1 in FIG. 7, images are continuous at the boundary BL12 of the right triangle regions TR1 and TR2, the boundary BL23 of the right triangle regions TR2 and TR3, and the boundary BL34 of the right triangle regions TR3 and TR4. A rendering process is performed to generate a tetrahedral environment texture. Accordingly, as shown in A2 of FIG. 7, when the blurring process is performed on the tetrahedral environment texture, the blurring process results are correct in the pixels near the boundaries BL12, BL23, and BL34, and the correct blurring process is performed. Can be realized. Also, for example, it is easy to generate a blurred image that can be used for mipmaps and low-index specular reflection. By performing such blurring processing, high-quality and realistic environment mapping can be realized.

  Note that the effect processing applied to the tetrahedral environment texture generated in the present embodiment is not limited to the blurring processing as shown in FIG. 5C, and various processing can be considered. For example, not only pixel color information (pixel information) averaging processing, but also weighted averaging processing, processing using a predetermined function, pixel replacement processing, and the like may be used. Further, effect processing such as edge detection (emphasis) processing other than blur processing may be used. In other words, the effect processing according to the present embodiment may be effect processing so that a correct result can be obtained when images at the boundary between right-angled triangular regions are continuous.

2.2 Conversion to Cube Environment Texture Cube environment mapping may be supported in hardware in the image generation system. On the other hand, tetrahedral environment mapping is often not supported by hardware. Therefore, in the present embodiment, a method of generating a cube environment texture by converting a tetrahedral environment texture is adopted.

  Specifically, a tetrahedral object OBS as shown in FIG. A tetrahedral environment texture dynamically generated in real time is mapped to the tetrahedral object OBS. In this embodiment, the cube environment texture is generated using the tetrahedral object OBS to which the tetrahedral environment texture is mapped in this way.

  Specifically, as shown in FIG. 8A, the tetrahedral object OBS is configured by first to fourth primitive surfaces SS1, SS2, SS3, and SS4 (polygons). Then, as shown in the development view of the tetrahedral object OBS of C1 in FIG. 8B, these primitive surfaces SS1, SS2, SS3, and SS4 have a right triangle by the method of FIGS. 4A to 4D. The right triangle images IMT1, IMT2, IMT3, and IMT4 drawn in the regions TR1, TR2, TR3, and TR4 are mapped.

  That is, texture coordinates are set for the vertices VSA, VSB, and VSC of the tetrahedral object OBS so that these right triangle images IMT1, IMT2, IMT3, and IMT4 are mapped to the primitive surfaces SS1, SS2, SS3, and SS4. . Based on the texture coordinates, the tetrahedral environment texture indicated by C2 in FIG. 8B is read from the texture storage unit 178 and mapped to the tetrahedral object OBS. By performing such texture mapping, the image transformed into the right triangle image in FIG. 5A returns to the original equilateral triangle image.

  Then, the virtual camera VC is arranged in the tetrahedral object OBS (center point), and the line-of-sight directions of the virtual camera VC are set to the fifth, sixth, seventh, eighth, ninth as shown in FIG. , 10th directions D5, D6, D7, D8, D9, D10. Then, fifth, sixth, seventh, eighth, ninth, and tenth rendering processes are performed. By doing so, a cube environment texture as shown in FIG. 9B is generated.

  Specifically, for example, the visual line direction of the virtual camera VC arranged in the tetrahedral object OBS is set to the D5 direction and the fifth rendering process is performed, and the generated image is drawn in the square (rectangular) region CR5. To do. Similarly, the line-of-sight direction of the virtual camera VC arranged in the OBS is set to the D6, D7, D8, D9, and D10 directions, and the sixth, seventh, eighth, ninth, and tenth rendering processes are performed. The generated image is drawn in square (rectangular) regions CR6, CR7, CR8, CR9, and CR10. By doing so, a cube environment texture as shown in FIG. 10 can be generated.

  Then, a cube environment mapping process to an object is performed using the generated cube environment texture. For example, cube environment mapping is performed using an image generation system that supports cube environment mapping. For example, by performing cube environment mapping using a cube environment texture on a moving object such as a car or train, a realistic image in which the surrounding environment is reflected on the moving object can be generated.

  For example, if the cube environment texture is dynamically generated in real time, the environment image rendering process is required six times. In this regard, in the present embodiment, as shown in FIGS. 3A to 4D, the tetrahedral environment texture is generated by four rendering processes. Therefore, it is possible to reduce the number of rendering processes for generating dynamic environmental textures with a heavy processing load. Also, the cube environment texture generation process described with reference to FIGS. 8A to 9B has a lighter load than the environment image rendering process that requires the drawing of the background object around the moving object. Therefore, according to the present embodiment, the overall processing load can be reduced.

  Note that the environment mapping to the object (moving object) in the present embodiment is not limited to the cube environment mapping. For example, sphere environment mapping, paraboloid environment mapping, cylinder environment mapping, or the like may be used.

  For example, FIG. 11 shows an example of sphere environment mapping. In FIG. 11, an object OB (moving object) that is a target of environment mapping is arranged in a tetrahedral object OBS. A reflection vector RL is obtained based on the line-of-sight vector SL of the virtual camera and the normal vector N of the object. Then, the image information of the intersection IP of the straight line in the direction of the reflection vector RL and the tetrahedral object OBS is set as the image information of the reflection point RP of the object OB. By doing so, an image of the tetrahedral environment texture mapped to the tetrahedral object OBS is mapped to the object OB, and sphere environment mapping can be realized. Thus, in FIG. 11, the right triangle images IMT1, IMT2, IMT3, and IMT4 drawn in the right triangle regions TR1, TR2, TR3, and TR4 in FIG. Environment mapping for the object OB is performed using the tetrahedral object OBS to be mapped.

  When performing paraboloid environment mapping, for example, by mapping the generated tetrahedral environment texture to a mesh-like object, two paraboloid environment textures that appear as seen from the fisheye lens are generated, and paraboloid environment mapping is performed. Should be realized.

2.3 Detailed Processing Example Next, a detailed processing example of the present embodiment will be described with reference to the flowcharts of FIGS.

  First, the position and direction of a moving object such as a car or train are calculated (step S1). Specifically, based on operation data from the operation unit 160, a program, and the like, changes in the position and direction of the moving object for each frame are calculated in real time.

  Next, the position of the virtual camera is determined (step S2). Specifically, the position of the virtual camera is determined based on the position of the moving object. For example, the virtual camera is arranged at the position of the representative point of the moving object.

  Next, as shown in FIG. 3A, the line-of-sight direction of the virtual camera is set to the D1 direction to determine the matrix M1 (step S3). FIG. 14 shows an example of this matrix M1. In addition, the right triangle area TR1 of the texture area is set as a drawing area (step S4). That is, the viewport is set in the areas TR1 and TR2, and only TR1 is set in the drawing area. Then, as shown in FIG. 4A, a rendering process in the direction D1 is performed based on the matrix M1, and drawing is performed in the right triangle region TR1 (step S5).

  Next, as shown in FIG. 3B, the line-of-sight direction of the virtual camera is set to the D2 direction to determine the matrix M2 (step S6). Further, the right triangle region TR2 is set as a drawing region (step S7). Then, as shown in FIG. 4B, rendering processing in the direction D2 is performed based on the matrix M2, and drawing is performed in the right triangle region TR2 (step S8).

  Next, as shown in FIG. 3C, the line-of-sight direction of the virtual camera is set to the D3 direction to determine the matrix M3 (step S9). Further, the right triangle region TR3 is set as a drawing region (step S10). Then, as shown in FIG. 4C, a rendering process in the D3 direction is performed based on the matrix M3, and drawing is performed in the right triangle region TR3 (step S11).

  Next, as shown in FIG. 3D, the line-of-sight direction of the virtual camera is set to the D4 direction to determine the matrix M4 (step S12). Further, the right triangle region TR4 is set as a drawing region (step S13). Then, as shown in FIG. 4D, rendering processing in the D4 direction is performed based on the matrix M4, and drawing is performed in the right triangle region TR4 (step S14).

  By doing so, a tetrahedral environment texture as shown in FIG. 6 is generated.

  Next, the matrices M1, M2, M3, and M4 in FIG. 14 will be described. For example, the matrix M1 is a matrix obtained by multiplying the view matrix V1, the projection matrix P, and the matrices m1, m2, m3, and m4.

  Here, V1 is a view matrix when viewing the (-1, -1, +1) direction from the origin with the (+1, +1, +1) direction as the upward direction of the virtual camera. With this view matrix V1, the viewing direction of the virtual camera can be set to the D1 direction. Further, the upward direction (tilt) of the virtual camera is set so that the vertices of the equilateral triangle have a positional relationship as shown in FIG.

  Further, as shown in FIG. 15, the isosceles triangle TR is moved by +1/3 along the Y direction by the matrix m1. As a result, the triangle TR enters the quadrangle QD. Note that the equilateral triangle of the tetrahedral object is transformed into an isosceles triangle by the projection matrix P.

  Next, the triangle TR is moved by −1 along the Y direction by the matrix m2. As a result, the origin is located at the bottom of the triangle TR. Next, the triangle TR is transformed into a right triangle by the matrix m3. The triangle TR is moved by +1 along the Y direction by the matrix m4. As a result, the right triangle TR enters the quadrangle QD.

  Next, cube environment texture generation and texture mapping processing will be described using the flowchart of FIG. First, data of the tetrahedral object of FIG. 8A to which the tetrahedral environment texture is mapped is read (step S21).

  Next, as shown in FIG. 9A, the line-of-sight direction of the virtual camera is set to the D5 direction to determine the matrix M5 (step S22). Further, rendering processing is performed based on the matrix M5, and drawing is performed in the region CR5 of FIG. 9B, which is a texture region (step S23).

  Similarly, the line-of-sight direction of the virtual camera is set to the directions D6, D7, D8, D9, and D10 to determine the matrices M6, M7, M8, M9, and M10 (steps S24, S26, S28, S30, and S32). In addition, rendering processing is performed based on the matrices M6, M7, M8, M9, and M10, and rendering is performed in the regions CR6, CR7, CR8, CR9, and CR10 in FIG. 9B that are texture regions (steps S25, S27, S29, and S31) , S33). The generated cube environment texture is mapped to the moving object (step S34). As described above, a realistic image in which the surrounding environment is reflected on the moving object is generated.

3. Hardware Configuration FIG. 16 shows an example of a hardware configuration that can realize this embodiment. The main processor 900 operates based on a program stored in a DVD 982 (information storage medium, which may be a CD), a program downloaded via the communication interface 990, a program stored in the ROM 950, or the like. Perform processing, sound processing, etc. The coprocessor 902 assists the processing of the main processor 900, and executes matrix operation (vector operation) at high speed. For example, when a matrix calculation process is required for a physical simulation for moving or moving an object, a program operating on the main processor 900 instructs (requests) the process to the coprocessor 902.

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

  The drawing processor 910 executes drawing (rendering) processing of an object composed of primitive surfaces such as polygons and curved surfaces. When drawing an object, the main processor 900 uses the DMA controller 970 to pass the drawing data to the drawing processor 910 and, if necessary, transfers the texture to the texture storage unit 924. Then, the drawing processor 910 draws the object in the frame buffer 922 while performing hidden surface removal using a Z buffer or the like based on the drawing data and texture. The drawing processor 910 also performs α blending (translucent processing), depth cueing, mip mapping, fog processing, bilinear filtering, trilinear filtering, anti-aliasing, shading processing, and the like. When a programmable shader such as a vertex shader or a pixel shader is installed, the vertex data is created / changed (updated) and the drawing color of a pixel (or fragment) is determined according to the shader program. When an image for one frame is written in the frame buffer 922, the image is displayed on the display 912.

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

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

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

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

  Although the present embodiment has been described in detail as described above, it will be easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Accordingly, all such modifications are included in the scope of the present invention. For example, in the specification or the drawings, different terms (first, second, third, fourth triangle regions, first, second, third, fourth triangle images, textures) that are broader or synonymous at least once. The terms (first, second, third, fourth right triangle regions, first, second, third, fourth right triangle images, rectangular texture regions, etc.) Alternatively, the different terms can be used anywhere in the drawings.

  Further, the tetrahedral environment texture generation method and the environment texture mapping method are not limited to those described in the present embodiment, and methods equivalent to these methods are also included in the scope of the present invention. For example, the line-of-sight direction of the virtual camera and the order of rendering processing are not limited to those shown in FIGS. 3A to 4D, and various modifications can be made. Also, the rendering processing method is not limited to the method of FIGS. 3 (A) to 4 (D). Also, the environment texture mapping method is not limited to the cube environment mapping method described with reference to FIGS. 8A to 10, and various environment mapping methods can be employed.

  In the present embodiment, the case where the regions TR1, TR2, TR3, and TR4 are right triangle regions has been described. However, these regions TR1, TR2, TR3, and TR4 may be triangular regions that are not right triangles.

  The present invention can be applied to various games. 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 game images, and a mobile phone. it can.

The example of a functional block diagram of the image generation system of this embodiment. Explanatory drawing of tetrahedral environment mapping. 3A to 3D are explanatory diagrams of a tetrahedral environment texture generation method. 4A to 4D are explanatory diagrams of a tetrahedral environment texture generation method. 5A is an explanatory diagram of a tetrahedral environment texture generation method, and FIGS. 5B and 5C are explanatory diagrams of a comparative example method and its problems. The example of the tetrahedral environment texture produced | generated by this embodiment. Explanatory drawing of the effect processing method with respect to a tetrahedral environment texture. 8A and 8B are explanatory views of a cube environment texture generation method. 9A and 9B are explanatory diagrams of a cube environment texture generation method. The example of the cube environment texture produced | generated by this embodiment. Explanatory drawing at the time of using sphere environment mapping. The detailed example of the process of this embodiment. The detailed example of the process of this embodiment. Explanatory drawing of the matrix used by this embodiment. Explanatory drawing of the matrix used by this embodiment. Hardware configuration example.

Explanation of symbols

100 processing unit, 110 object space setting unit, 112 movement / motion processing unit,
114 virtual camera control unit, 120 drawing unit, 122 tetrahedral environment texture generation unit,
124 effect processing unit, 126 cube environment texture generation unit,
128 texture mapping unit, 130 sound generation unit, 160 operation unit,
170 storage unit, 172 main storage unit, 174 drawing buffer,
176 model data storage unit, 178 texture storage unit,
180 information storage medium, 190 display unit, 192 sound output unit,
194 Portable information storage device, 196 communication unit

Claims (11)

A program for generating an image,
A tetrahedral environment texture generation unit for generating a tetrahedral environment texture;
A first triangular region, a second triangular region sharing a side with the first triangular region, a third triangular region sharing a side with the second triangular region, and the third triangular region A texture storage unit in which a texture region formed by the fourth triangular region sharing the side is secured;
As a texture mapping unit that performs texture mapping processing on objects,
Make the computer work,
The tetrahedral environment texture generation unit
The visual line direction of the virtual camera is set to the first, second, third, and fourth directions to perform the first, second, third, and fourth rendering processes, and the first, second, third, By drawing the first, second, third, and fourth images in the first, second, third, and fourth triangular regions of the texture region by the fourth rendering process, the first, A program for generating a tetrahedral environment texture in the texture region formed by the second, third, and fourth triangular regions. In claim 1,
The first, second, third and fourth triangular regions are right triangle regions;
A program characterized in that a rectangular texture area formed by the first, second, third, and fourth triangular areas is secured in the texture storage unit. In claim 1 or 2,
The tetrahedral environment texture generation unit
The first, second, and second shapes of the first, second, third, and fourth images are transformed into the shape of the first, second, third, and fourth triangular regions. A program for generating the tetrahedral environment texture by performing third and fourth rendering processes. In any one of Claims 1 thru | or 3,
The tetrahedral environment texture generation unit
The first, second, and second images are continuous at the boundary between the first and second triangular regions, the boundary between the second and third triangular regions, and the boundary between the third and fourth triangular regions. A program characterized in that the tetrahedral environment texture is generated by performing third and fourth rendering processes. In any one of Claims 1 thru | or 4,
The program characterized by including the effect process part which performs an effect process with respect to the said tetrahedral environment texture produced | generated in the said rectangular texture area | region. In any one of Claims 1 thru | or 5,
Based on the generated tetrahedral environment texture, the computer functions as a cube environment texture generation unit that generates a cube environment texture.
The texture mapping unit
A program for performing texture mapping processing based on a generated cube environment texture. In claim 6,
The cube environment texture generation unit
The first, second, third, and fourth triangular images drawn in the first, second, third, and fourth triangular regions are the first, second, third, and fourth primitive planes. The cube environment texture is generated by using a tetrahedron object mapped to the program. In claim 7,
The cube environment texture generation unit
The line-of-sight direction of the virtual camera set in the tetrahedral object is set to the fifth, sixth, seventh, eighth, ninth, and tenth directions to set the fifth, sixth, seventh, and eighth directions. A program for generating the cube environment texture by performing the ninth and tenth rendering processes. In any one of Claims 1 thru | or 5,
The texture mapping unit
The first, second, third, and fourth triangular images drawn in the first, second, third, and fourth triangular regions are the first, second, third, and fourth primitive planes. A program characterized by performing environment mapping on an object using a tetrahedral object mapped to the object.   A computer-readable information storage medium, wherein the program according to any one of claims 1 to 9 is stored. An image generation system for generating an image,
A tetrahedral environment texture generation unit for generating a tetrahedral environment texture;
A first triangular region, a second triangular region sharing a side with the first triangular region, a third triangular region sharing a side with the second triangular region, and the third triangular region A texture storage unit in which a texture region formed by the fourth triangular region sharing the side is secured;
A texture mapping unit that performs texture mapping processing on the object,
The tetrahedral environment texture generation unit
The visual line direction of the virtual camera is set to the first, second, third, and fourth directions to perform the first, second, third, and fourth rendering processes, and the first, second, third, By drawing the first, second, third, and fourth images in the first, second, third, and fourth triangular regions of the texture region by the fourth rendering process, the first, A tetrahedral environment texture is generated in the texture region formed by the second, third, and fourth triangular regions.