JP2005275796A - 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 to realize a realistic representation of a lighting object. <P>SOLUTION: A virtual normal vector N for a lighting effect is set at each point of the lighting object LOB. An angle parameter AP representing how large an angle made by a line of sight direction vector SD of a virtual camera VC and the virtual normal vector N is calculated based on virtual normal vector information. At least one of a size, an α value, luminance, brightness and color saturation of a billboard primitive face BP for a lighting effect, which is disposed and set so as to squarely face the virtual camera VC, is established based on the angle parameter AP, and a billboard primitive face N is drawn. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  Conventionally, an image generation system (game system) that generates an image that can be viewed from a virtual camera (a given viewpoint) in an object space (virtual three-dimensional space) in which an object such as a character is set is known. It is popular as a place to experience so-called virtual reality. Taking an example of an image generation system that generates an image of a baseball game, a defensive player operates a pitcher character to throw a ball, and an attacking player operates a batter character to hit a thrown ball. Generate an image.

  In such an image generation system, it is desirable to be able to express realistically, for example, a highlight effect of night game lighting in a stadium. As a technique for realizing such highlight expression, there is a technique in which a highlight effect object is arranged on a display object, and an image in which a highlight effect image is displayed overlapping the display object is generated.

However, this method has a problem that even if the direction of the line-of-sight vector of the virtual camera changes, the appearance of the highlight effect does not change.
JP 2001-325605 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 that enable realistic expression of a lighting object. .

  The present invention is an image generation system for generating an image that can be viewed from a virtual camera in an object space, and an object space setting unit that sets a plurality of objects including a lighting object in the object space, and a virtual camera control that controls the virtual camera An angle formed by a virtual normal vector information storage unit that stores information on a virtual normal vector for a lighting effect set at each point of the lighting object, and a visual direction vector and a virtual normal vector of the virtual camera An angle parameter that represents the size of a parameter calculation unit that is obtained based on the virtual normal vector information, and the size, α value, brightness, and size of the billboard primitive surface for a lighting effect that is arranged and set to face the virtual camera. Set at least one of brightness and saturation based on the angle parameter A billboard setting unit that relates to an image generation system that includes a drawing unit for drawing the billboard primitive surface. 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.

  According to the present invention, a virtual normal vector for lighting effects is set at each point of the lighting object. Then, an angle parameter indicating the magnitude of the angle formed by the visual line direction vector and the virtual normal vector of the virtual camera is obtained based on the virtual normal vector information. Then, a billboard primitive surface for the lighting effect is drawn in which at least one of the size, α value, luminance, brightness, and saturation is set based on the angle parameter. This makes it possible to realistically represent the lighting object while minimizing the number of primitive surfaces used.

  Further, in the image generation system, the program, and the information storage medium according to the present invention, as the virtual normal vector information storage unit moves from the center point of the illumination surface, which is the surface on which the illumination image of the illumination object is drawn, toward the end side, Information on the virtual normal vector set so that the angle formed by the virtual normal vector and the illumination surface may gradually decrease from 90 degrees may be stored.

  In this way, it is possible to generate a realistic image in which a highlight effect is displayed on the left or right side of the illumination surface of the lighting object when viewed from a virtual camera set on the left front side or right front side of the lighting object, for example. .

  In the image generation system, the program, and the information storage medium according to the present invention, the billboard setting unit sets an α value of a billboard primitive surface based on the angle parameter, and the drawing unit maps an illumination texture. The billboard primitive surface may be drawn by α addition blending based on the set α value.

  In this way, the α value changes according to the angle parameter, and the brightness of the highlight expressed on the billboard primitive surface changes according to the α value, thereby realizing a realistic image expression. .

  In the image generation system, the program, and the information storage medium according to the present invention, the billboard setting unit may perform setting processing for a plurality of types of billboard primitive surfaces having different base sizes.

  In this way, various image representations of illumination can be realized.

  In the image generation system, the program, and the information storage medium according to the present invention, the drawing unit draws a base primitive surface to which the base texture of the lighting effect is mapped, and the building primitive is overlapped with the base primitive surface. The board primitive surface may be drawn.

  In this way, it is possible to generate an image in which the entire lighting object looks shining.

  In the image generation system, the program, and the information storage medium according to the present invention, the drawing unit adds a billboard primitive surface to a point obtained by perspectively projecting each point of the illumination object on which the virtual normal vector is set on the screen. You may make it draw.

  In this way, the billboard primitive surface drawing process can be simplified.

  In the image generation system, the program, and the information storage medium according to the present invention, the billboard setting unit sets the size of the billboard primitive plane based on the angle parameter, and the set size and the coordinates of the perspective projection point are set. Based on the above, the vertex coordinates of the billboard primitive surface may be obtained, and the drawing unit may draw the billboard primitive surface specified by the obtained vertex coordinates.

  In this way, the size of the billboard primitive surface changes based on the angle parameter, and the overall brightness of the highlight expressed on the billboard primitive surface changes, and a realistic image can be generated. .

  In the image generation system, the program, and the information storage medium according to the present invention, the parameter calculation unit rotates the virtual normal vector based on a camera rotation matrix of the virtual camera, and the Z component of the rotated virtual normal vector May be obtained as the angle parameter.

  In this way, the angle parameter can be obtained with a small processing load.

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

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

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

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

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

  The processing unit 100 includes an object space setting unit 110, a movement / motion processing unit 112, a virtual camera control unit 114, a parameter calculation unit 116, a billboard setting unit 118, 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 characters, buildings, stadiums, cars, trees, columns, walls, and maps (terrain). (Object) is set in the object space. That is, the position and rotation angle (synonymous with direction and direction) of the object (model object) in the world coordinate system are determined, and the rotation angle (X, Y, Z axis around the position (X, Y, Z)) is determined. Arrange objects at (rotation angle).

  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, an object (moving 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 (position or rotation angle of each part object) every frame (1/60 second). I do. A frame is a unit of time for performing object movement / motion processing (simulation processing) and image generation processing.

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

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

  The parameter calculation unit 116 performs calculation processing (update processing) of various parameters used for the game processing. Here, the parameter is a variable that qualitatively and quantitatively represents a game situation, a character state, etc., and is used for various determinations in the game processing (determination of game progress, determination of game results, etc.). .

  Specifically, in the present embodiment, the object space setting unit 110 places and sets a lighting object (a model object for expressing lighting) in the object space. The virtual normal vector information storage unit 176 of the storage unit 170 stores information on the virtual normal vector for lighting effects (for example, the X, Y, Z components of the virtual normal vector and the coordinates of the start point of the virtual normal vector). To do. This virtual normal vector (the start point of the virtual normal vector) is set at each point of a lighting object (for example, an object representing night lighting in a stadium or a stadium). For example, when the lighting object has a plurality of lights, each point corresponds to each position of these lights, and may be set on the surface of the lighting object, or may be a position away from the lighting object. It may be set to. The virtual normal vector is a virtual normal vector used for highlight expression of illumination. The direction of the virtual normal vector can be set not only in the direction perpendicular to the surface of the illumination object but also in any other direction, and in this sense, it is called a “virtual” normal vector.

  Then, the parameter calculation unit 116 obtains an angle parameter indicating the magnitude of the angle formed between the visual line direction vector of the virtual camera and the virtual normal vector based on the virtual normal vector information (vector component or the like). As such an angle parameter (AP), a virtual normal vector is rotated (coordinate conversion) based on the camera rotation matrix (rotation matrix around the X axis, Y axis, and Z axis) of the virtual camera, and after rotation Can be obtained by inverting the sign (AP = −NZ) of the Z component (NZ) of the virtual normal vector. Alternatively, the inner product (AP = SD · N) of the visual direction vector (SD) of the virtual camera and the virtual normal vector (N) may be used as the angle parameter.

  The billboard setting unit 118 performs billboard setting processing (generation processing). Specifically, at least one of the size, α value, luminance, brightness, and saturation of a billboard primitive surface (polygon, sprite, etc.) for lighting effect is set based on the angle parameter (AP). In other words, billboard primitive surface data (polygon data, sprite data) whose size, α value, luminance, brightness, and saturation are set by the angle parameter is generated. More specifically, the billboard setting unit 118 is based on each angle parameter obtained from each virtual normal vector set at each point (each vertex) of the lighting object and the visual direction vector of the virtual camera. The size, α value, brightness, lightness, and saturation of each billboard primitive plane placed and set at each point (position corresponding to each point) are set. In this case, the billboard primitive surface is arranged so as to face the virtual camera. In other words, the billboard primitive surface is 180 degrees so that the angle formed by the normal vector of the illumination surface (surface on which the illumination image is drawn. Surface on which the illumination texture is mapped) and the visual direction vector of the virtual camera is 180 degrees. Placement is set. This billboard primitive plane may be placed and set in a three-dimensional object space, or a perspective projection on a two-dimensional screen (perspective projection screen) corresponding to each point (start point of each virtual normal vector) of the illumination object. The arrangement may be set to a point (perspective transformation point).

  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. In the case of generating a so-called three-dimensional game image, first, geometric processing such as coordinate transformation (world coordinate transformation, camera coordinate transformation), clipping processing, or perspective transformation is performed, and drawing data ( The position coordinates, texture coordinates, color data, normal vector, α value, etc.) of the vertexes of the primitive surface are created. Based on the drawing data (primitive surface data), the object (one or a plurality of primitive surfaces) after perspective transformation (after geometry processing) is stored as image data in units of pixels such as a drawing buffer 172 (frame buffer, intermediate buffer, etc.) Can be drawn in a VRAM). Thereby, an image that can be seen from the virtual camera (given viewpoint) in the object space is generated.

  The drawing unit 120 includes a texture mapping unit 122 and an α blending unit 124.

  The texture mapping unit 122 performs processing for mapping the texture (texel value) stored in the texture storage unit 174 to an object. Specifically, the texture (surface properties such as color and α value) is read from the texture storage unit 174 using the texture coordinates set (given) at the vertices of the object (primitive surface). Then, a texture that is a two-dimensional image or pattern is mapped to the object. In this case, processing for associating pixels and texels, bilinear interpolation (texel interpolation), and the like are performed.

  The α blending unit 124 performs α blending processing (usually α blending, α addition blending, α subtraction blending, or the like) based on the α value (A value). For example, in the case of normal α blending, the following processing is 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)
On the other hand, in the case of addition α blending, the following processing is 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)
Here, R ₁ , G ₁ , and B ₁ are RGB components of an image (original image) already drawn in the drawing buffer 172, and R ₂ , G ₂ , and B ₂ should be drawn in the drawing buffer 172. This is the RGB component of the image. R _Q , G _Q , and B _Q are RGB components of an image obtained by α blending. The α value is information that can be stored in association with each pixel (texel, dot), for example, plus alpha information other than color information. The α value can be used as mask information, translucency (equivalent to transparency and opacity), bump information, and the like.

  In the present embodiment, the billboard setting unit 118 sets the α value of the billboard primitive surface based on the angle parameter obtained by the parameter calculation unit 116. Then, the texture mapping unit 122 (drawing unit 120) maps the illumination texture (highlight texture) stored in the texture storage unit 174 to the billboard primitive surface. Further, the α blending unit (drawing unit 120) sets the position (each point) corresponding to each point of the lighting object based on the α value set by the billboard setting unit 118 for the billboard primitive surface to which the lighting texture is mapped. , The perspective projection points of each point, etc.) are drawn by α addition blending. Thereby, the highlight of illumination can be expressed realistically.

  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. Next, the method of this embodiment will be described with reference to the drawings. In the following, the case where the method of the present embodiment is used for highlight expression of the night game lighting of the stadium (the stadium) will be mainly described. However, the method of the present embodiment is only the highlight expression of such night game lighting. It can be applied to various image representations.

2.1 Highlight Expression Using Virtual Normal Vector FIG. 2 shows an example of a lighting object LOB. This LOB is a model object for expressing lighting installed in a stadium or the like. This illumination object LOB has a plurality of lights, and in the present embodiment, the fact that these lights are directed in different illumination directions is expressed in a pseudo manner using virtual normal vectors.

  FIG. 3 shows an example of the virtual normal vector N set at each point of the illumination object LOB. As shown in FIG. 4A, these virtual normal vectors N are not necessarily orthogonal to the illumination surface of the illumination object LOB (surface on which the illumination image is drawn, surface on which the illumination texture is mapped). In this sense, in the present embodiment, this vector is referred to as a “virtual” normal vector.

  Specifically, in the present embodiment, the angle formed by the virtual normal vector N and the illumination surface is 90 degrees from the center point of the illumination surface of the illumination object LOB toward the end sides (first to fourth sides). It is set to decrease (decrease gradually). For example, at the center point of the illumination surface of the illumination object LOB, the angle formed by the virtual normal vector N and the illumination surface is 90 degrees as indicated by C1 in FIG. On the other hand, at the edge of the illumination surface, as shown by C2 and C3, the angle (smaller angle) formed by the virtual normal vector N and the illumination surface is smaller than 90 degrees. Thus, in this embodiment, the direction of the virtual normal vector N is set so as to spread toward the end side from the center point of the illumination surface toward the end side. By doing so, as shown in FIG. 4A, when viewed with the virtual camera VC set on the front left side of the lighting object LOB, for example, an image in which highlights are formed on the left side of the lighting object LOB is displayed. It is possible to create a realistic expression of night lighting.

  The setting of the direction of the virtual normal vector N and the start point position are not limited to the examples in FIGS. 3 and 4A, and various modifications can be made. Further, each point (starting point of N) of the illumination object LOB for which the virtual normal vector N is set may be a point on the illumination surface of the LOB or a point away from the illumination surface. For example, when expressing the illumination as shown in FIG. 2, it is desirable to set each point at the position of each light included in the illumination object LOB. The information of the virtual normal vector N includes the vector component (NX, NY, NZ) of each virtual normal vector N, the coordinates (XS, YS, ZS) of the start point position of each virtual normal vector N, and the like. Can do.

  As shown in FIG. 4B, in the present embodiment, an angle representing the magnitude of the angle θ formed by the virtual normal vector N set as shown in FIG. 4A and the line-of-sight direction vector SD of the virtual camera VC. A parameter AP (magnification parameter) is obtained based on the virtual normal vector information. This angle parameter AP is a parameter corresponding to the inner product of the virtual normal vector N and the line-of-sight normal vector SD. In the present embodiment, the size and α value (brightness, brightness, and saturation) of the billboard primitive plane (billboard polygon, billboard sprite) for lighting effects may be used based on the angle parameter AP. The same) is set.

  For example, when the virtual camera VC is set as shown in FIG. 5A, in D1 of FIG. 5A, the angle formed by the virtual normal vector N and the line-of-sight direction vector SD is close to 180 degrees. Accordingly, the value of the angle parameter AP indicating the magnitude of the angle θ formed by N and SD also increases (for example, AP = about 1.0), and the size of the billboard primitive plane BP set at the starting point of the virtual normal vector N The α value is also set to a large value. And this large-sized billboard primitive surface is added by α blending (α blending in a broad sense) based on the α value set to this large value, and the position corresponding to the starting point of the virtual normal vector N ) Is drawn.

  On the other hand, in D2 of FIG. 5A, the angle formed by the virtual normal vector N and the line-of-sight direction vector SD is close to 90 degrees. Accordingly, the value of the angle parameter AP also decreases (for example, AP = 0.0), and the size and α value of the billboard primitive plane BP set at the starting point of the virtual normal vector N are also set to small values. The small-sized billboard primitive surface is drawn at the position by addition α blending based on the α value set to the small value.

  When the virtual camera VC is set as shown in FIG. 5B, the angle formed by the virtual normal vector N and the line-of-sight direction vector SD is close to 180 degrees at E1 in FIG. 5B. Accordingly, the value of the angle parameter AP is also increased, and the billboard primitive surface BP having a large α value set with a large size is drawn at that position. On the other hand, at E2 and E3 in FIG. 5B, the angle formed by the virtual normal vector N and the line-of-sight direction vector SD is smaller than 180 degrees. Accordingly, the value of the angle parameter AP is also reduced, and the billboard primitive surface BP having a small α value set with a small size is drawn at that position.

  FIG. 6, FIG. 7, and FIG. 8 show examples of images of the illumination object LOB generated by the method of the present embodiment.

  FIG. 6 is an example of an image generated when a virtual camera is arranged on the left front side of the illumination object LOB as shown in FIG. As shown in FIG. 6, a strong highlight is generated on the left side of the illumination object LOB as viewed from the virtual camera. On the other hand, the highlight is weak on the right side of the LOB.

  FIG. 7 is an example of an image generated when a virtual camera is arranged near the front of the illumination object LOB as shown in FIG. As shown in FIG. 7, a strong highlight is generated near the center of the illumination object LOB as viewed from the virtual camera. On the other hand, highlights are relatively weak on the right and left sides of the LOB.

  FIG. 8 is an example of an image generated when a virtual camera is arranged on the right-hand side of the lighting object LOB. As shown in FIG. 8, a strong highlight is generated on the right side of the illumination object LOB as viewed from the virtual camera.

  As described above, in the present embodiment, highlights generated in real-time night lighting are successfully expressed realistically using a pseudo technique.

  For example, the following method is also conceivable as a first comparative example of the present embodiment. That is, when the illumination object is located at the center of the screen, the highlight of the entire illumination surface of the illumination object is strengthened. On the other hand, when the illumination object is located at a position away from the center of the screen, the highlight of the entire illumination surface is weakened.

  However, in the real world, even when the night lighting is located at a position away from the center of the shooting screen of the baseball broadcast camera, for example, as shown in FIG. May cause highlights. Therefore, the above-described method of the first comparative example that controls the intensity of the highlight on the entire illumination surface according to the position of the illumination object on the screen as described above cannot realistically represent such real-world night illumination.

  On the other hand, in this embodiment, by setting a virtual normal vector N as shown in FIGS. 5A and 5B, realistic highlights of night lighting as shown in FIGS. Expression can be realized. For example, if the virtual normal vector N is set as D1 in FIG. 5A, even if the illumination object LOB is reflected at a position away from the center of the screen, the virtual normal vector N of D1 As shown in FIG. 6, a highlight is generated on the left side of the lighting object LOB. Therefore, it is possible to generate an image that looks as if the light directly facing the virtual camera is arranged on the left side of the lighting object LOB, thereby realizing realistic expression of lighting.

  Furthermore, in this embodiment, as shown in FIGS. 5A and 5B, the virtual normal vector N and the billboard primitive plane BP are not necessarily orthogonal. Specifically, the virtual normal vector N and the billboard primitive plane BP are orthogonal to each other at points where strong highlights occur (points indicated by D1, E1), but other points (points indicated by E2, E3) Is not orthogonal.

  The billboard primitive plane BP is arranged and set so as to always face the virtual camera VC regardless of the direction of the virtual normal vector N. In this way, a wide range of illumination images can be generated with a small number of primitive surfaces.

  For example, as a second comparative example of the present embodiment, the billboard primitive plane BP is arranged and set so as to face the virtual camera VC, and the virtual normal vector N is set so as to be always orthogonal to the billboard primitive plane BP. A technique to do this is also possible.

  However, in the method of the second comparative example, the angle formed by the line-of-sight direction vector SD and the virtual normal vector N is always 180 degrees regardless of where the virtual camera VC is placed. ~ Realistic expression of night lighting as shown in Fig. 8 cannot be realized.

  As a third comparative example, there is also a method of arranging a normal primitive surface that is not a billboard so as to be orthogonal to the virtual normal vector set as shown in FIG. 4A without using the billboard primitive surface. Conceivable. However, since the billboard primitive surface is not used in the method of the third comparative example, the number of primitive surfaces necessary for generating an illumination image increases, resulting in an increase in processing load.

  On the other hand, in the present embodiment, as shown in FIGS. 4A to 5B, the billboard primitive plane is set and set independently of the setting of the virtual normal vector. Therefore, while realizing a realistic expression of night lighting as shown in FIGS. 6 to 8 using the virtual normal vector N set as shown in FIG. 4A, FIG. 5A and FIG. By arranging and setting the billboard primitive plane as shown in (2), the number of primitive planes used can be saved. Therefore, realistic highlight expression can be realized with a small processing load and a small memory capacity.

2.2 Setting α Value FIGS. 9A and 9B show examples of illumination textures mapped to the billboard primitive surface. In the present embodiment, the billboard setting unit 118 performs setting processing for a plurality of types of billboard primitive surfaces having different base sizes. The lighting texture of FIG. 9A is mapped to the first type of billboard primitive surface having a small base size, and the lighting of FIG. 9B is applied to the second type of billboard primitive surface having a large base size. Texture is mapped. The second type billboard primitive surface having a large base size is scattered and arranged at several locations on the illumination surface of the illumination object LOB. As a result, it is possible to realistically represent a state in which only some of the lights appear to shine strongly in night lighting or the like. Note that the types of billboard primitive surfaces with different base sizes are not limited to two, and may be three or more. The base size is a basic size (minimum size) when changing the size of the billboard primitive surface based on the angle parameter AP.

  In the present embodiment, the α value of the billboard primitive surface is set based on the angle parameter AP obtained by the method of FIG. Then, positions (for example, perspective projection points) corresponding to each point of the illumination object LOB on the billboard primitive surface to which the illumination texture as shown in FIGS. 9A and 9B is mapped, based on the set α value. For example, drawing is performed by α addition blending. In this way, the billboard primitive plane is drawn on the background image by α addition blending, and images as shown in FIGS. 6 to 8 can be generated. In the left part of the lighting object LOB in FIG. 6, since the billboard primitive surface having a large α value is drawn, the color of the place approaches white due to α addition blending, and a strong highlight is generated. On the other hand, in the right part of the lighting object LOB in FIG. 6, since the billboard primitive surface having a small α value is drawn, the highlight becomes weak. As described above, in the present embodiment, realistic highlight expression is realized by controlling the α value of the billboard primitive surface based on the angle parameter AP.

  In the present embodiment, as shown in FIG. 10, the base primitive surface to which the base texture of the lighting effect is mapped is first drawn. This base texture is a texture serving as a base of the illumination texture shown in FIGS. The base primitive surface is a primitive surface arranged and set along the illumination surface of the illumination object LOB. In this embodiment, for example, a plurality of base primitive surfaces are arranged and set along the illumination surface.

  In this embodiment, the billboard primitive surface to which the illumination textures of FIGS. 9A and 9B are mapped is drawn so as to overlap the base primitive surface to which the base texture as shown in FIG. 10 is mapped. Thereby, an image of a lighting object in which a highlight effect as shown in FIG. 11 is expressed can be generated. For example, if only the billboard primitive surface for the lighting effect is drawn without drawing the base primitive surface as shown in FIG. 10, it becomes difficult to express a state in which the lighting object LOB appears to shine as a whole. On the other hand, if the base primitive surface as shown in FIG. 10 is drawn, the illumination image of the base texture is drawn also in the area between the billboard primitive surfaces. It will be possible to express realistically how it looks shining. Depending on the type of lighting object, a technique that does not draw such a base primitive surface may be employed.

2.3 Size Setting In this embodiment, as shown in FIG. 4B, the size is based on an angle parameter AP (inner product of SD and N) indicating the magnitude of the angle formed by the line-of-sight direction vector SD and the virtual normal vector N. The size (height and width) of the billboard primitive surface is set. For example, when the angle parameter AP is large (for example, AP = 1.0), the size of the billboard primitive surface is increased. When the AP is small (for example, AP = 0.0), the size of the billboard primitive surface is increased. Make it smaller. As described above, the billboard primitive surface drawing process whose size is set by the angle parameter AP can be realized by a technique as shown in FIGS. 12A and 12B, for example.

  In FIG. 12A, each point (starting point of N, light position) of the illumination object for which the virtual normal vector N is set is perspectively projected on the screen SC (perspective projection plane). A billboard primitive surface is drawn at the obtained perspective projection point. In this way, it is possible to draw a billboard primitive surface that is always facing the virtual camera with a simple process.

  In FIG. 12B, the sizes DX and DY (sizes in the X direction and Y direction) of the billboard primitive plane BP are set based on the angle parameter AP, and the set sizes DX and DY and the perspective projection point PP are set. Based on the coordinates (PX, PY), the coordinates of the vertices V1 to V4 of the billboard primitive plane BP are obtained. Then, the billboard primitive plane BP specified by the coordinates of the obtained vertices V1 to V4 is drawn. In this way, it is possible to always draw the billboard primitive surface BP directly facing the virtual camera by a simple process and change the size of the billboard primitive surface to be drawn according to the angle parameter AP. .

  When a sprite is used as the billboard primitive surface BP, the billboard sprite can be drawn only by obtaining and specifying the coordinates of two vertices (for example, V1 and V3). On the other hand, when a polygon is used as the billboard primitive surface BP, it is necessary to obtain and specify the coordinates of four vertices (examples V1 to V4). Therefore, in order to reduce the processing load, it is desirable to use a sprite that only needs to specify two vertices.

  Note that the billboard primitive surface drawing method is not limited to the method shown in FIGS. For example, a billboard primitive surface may be arranged at each point of the lighting object LOB in the three-dimensional object space, and the billboard primitive surface may be drawn by perspective transformation (perspective projection) on the screen. In this case, the rotation angle of the billboard primitive surface (rotation angles on the X, Y, and Z axes) may be controlled so that the billboard primitive surface always faces the virtual camera.

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

  First, the virtual normal vector is rotated based on the camera rotation matrix of the virtual camera (step S1). Thereby, the coordinate components (NX, NY, NZ) of the virtual normal vector in the camera coordinate system (viewpoint coordinate system) are obtained. Then, the angle parameter AP = −NZ is obtained by inverting the sign of the Z component NZ of the virtual normal vector after rotation (step S2). In this case, 0 ≦ AP ≦ 1 when the virtual normal vector is a front-facing vector as viewed from the virtual camera, and −1 ≦ AP <0 when the vector is a back-facing vector. More specifically, AP = −NZ = 1 when the angle formed by the virtual normal vector and the line-of-sight normal vector is 180 degrees, AP = −NZ = 0 when the angle is 90 degrees, and 0 degrees when the angle is 0 degrees. AP = −NZ = −1.

  Next, it is determined whether AP is smaller than 0 (whether it is facing down) (step S3). If AP <0, the process proceeds to step S9. On the other hand, when AP ≧ 0, an α value set for the billboard primitive surface (polygon, sprite) is obtained (step S4). Specifically, for example, the α value is obtained by a formula of α = AP × MAXα. Here, MAXα is the maximum α value.

  Next, as described with reference to FIG. 12A, a point PP (PX, PY) obtained by perspectively projecting each point (start point) of the illumination object to which the virtual normal vector is set on the screen is obtained (step S5). . Then, DX and DY are obtained based on the base sizes MINX and MINY, the enlargement ratios WDTX and WDTY, and the angle parameter AP (step S6). Specifically, DX and DY are obtained by the following formula: DX = MINX + AP × WDTX, DY = MINY + AP × WDTY. Note that MINX = MINY and WDTX = WDTY.

  Next, as described with reference to FIG. 12B, the upper left vertex V1 (X1, Y1) and the lower right vertex V3 (X3, Y3) of the billboard primitive surface are obtained (step S7). Specifically, V1 (X1, Y1) and V3 (X3, Y3) are obtained by the following formulas: X1 = PX-DX, Y1 = PY-DY, X3 = PX + DX, Y3 = PY + DY. Then, the billboard primitive plane (billboard sprite) specified by V1 and V3 is drawn by addition α blending based on the α value obtained in step S4 (step S8). Then, it is determined whether or not the processing for all the lights (virtual normal vectors) has been completed (step S9). If completed, the process returns to step S1, and the processing for the next light (virtual normal vectors) is performed. Migrate to

4). Hardware Configuration FIG. 14 shows an example of a hardware configuration capable of realizing this embodiment. The main processor 900 operates based on a program stored in a CD 982 (information storage medium), a program downloaded via the communication interface 990, a program stored in the ROM 950, or the like, and includes game processing, image processing, sound processing, and the like. Execute. 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 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 CD drive 980 accesses a CD 982 in which programs, image data, sound data, and the like are stored. The communication interface 990 performs data transfer with the outside via a network (communication line, high-speed serial bus).

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

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

  The present invention is not limited to that described in the above embodiment, and various modifications can be made. For example, terms (additional α blending, polygon sprites, etc.) cited as broad or synonymous terms (α blending, primitive surface, etc.) in the description in the specification or drawings are used in other descriptions in the specification or drawings. Can also be replaced with broad or synonymous terms.

  Also, the virtual normal vector placement method, billboard primitive surface placement method and drawing method, billboard primitive surface size and α value setting method are not limited to those described in this embodiment, and are equivalent to these. Techniques are also included in the scope of the present invention.

  In the present embodiment, the case where the brightness of the highlight effect (lighting effect) is controlled by controlling the α value of the billboard primitive surface has been described. However, the present invention is not limited to this, and brightness parameters such as brightness (R, G, B brightness), brightness, and saturation of the billboard primitive surface are controlled to control the brightness of the highlight effect. Also good.

  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 a game image, and a mobile phone. it can.

The example of a functional block diagram of the image generation system of this embodiment. An example of a lighting object. Setting example of virtual normal vector. 4A and 4B are explanatory diagrams of the method of this embodiment. 5A and 5B are also explanatory diagrams of the method of the present embodiment. The example of the image produced | generated by the method of this embodiment. The example of the image produced | generated by the method of this embodiment. The example of the image produced | generated by the method of this embodiment. 9A and 9B are examples of illumination textures. Explanatory drawing of a base texture and a base primitive surface. Explanatory drawing of the method of drawing a billboard primitive surface overlapping with a base primitive surface. FIGS. 12A and 12B are also explanatory diagrams of a drawing method of a billboard primitive surface. The flowchart of the specific process of this embodiment. Hardware configuration example.

Explanation of symbols

LOB lighting object, N virtual normal vector,
VC virtual camera, SD line-of-sight vector, BP billboard primitive surface,
100 processing unit, 110 object space setting unit, 112 movement / motion processing unit,
114 virtual camera control unit, 116 parameter calculation unit, 118 billboard setting unit,
120 drawing unit, 122 texture mapping unit, 124 α composition unit,
130 sound generation unit, 160 operation unit, 170 storage unit, 172 drawing buffer,
174 texture storage unit, 176 virtual normal vector information storage unit,
180 information storage medium, 190 display unit,
192 sound output unit, 194 portable information storage device, 196 communication unit

Claims (10)

A program for generating an image visible from a virtual camera in an object space,
An object space setting unit configured to place and set a plurality of objects including a lighting object in the object space;
A virtual camera control unit for controlling the virtual camera;
A virtual normal vector information storage unit that stores information on a virtual normal vector for a lighting effect set at each point of the lighting object;
A parameter calculation unit for obtaining an angle parameter indicating the magnitude of an angle formed by the visual line direction vector and the virtual normal vector of the virtual camera based on the virtual normal vector information;
A billboard setting unit configured to set at least one of a size, α value, luminance, brightness, and saturation of a billboard primitive surface for a lighting effect arranged and set to face the virtual camera based on the angle parameter; ,
As a drawing unit for drawing the billboard primitive surface,
A program characterized by causing a computer to function. In claim 1,
The virtual normal vector information storage unit is
A virtual set such that the angle formed by the virtual normal vector and the illumination plane gradually decreases from 90 degrees toward the end side from the center point of the illumination plane, which is the plane on which the illumination image of the illumination object is drawn. A program characterized by storing normal vector information. In claim 1 or 2,
The billboard setting unit
Set the alpha value of the billboard primitive surface based on the angle parameter,
The drawing unit
A program characterized in that a billboard primitive surface to which a lighting texture is mapped is drawn by α addition blending based on the set α value. In any one of Claims 1 thru | or 3,
The billboard setting unit
A program that performs setting processing of a plurality of types of billboard primitive surfaces having different base sizes. In any one of Claims 1 thru | or 4,
The drawing unit
A program that draws a base primitive surface to which a base texture of a lighting effect is mapped, and draws the billboard primitive surface so as to overlap the base primitive surface. In any one of Claims 1 thru | or 5,
The drawing unit
A program for drawing a billboard primitive plane at a point obtained by perspectively projecting each point of a lighting object to which the virtual normal vector is set on a screen. In claim 6,
The billboard setting unit
Set the size of the billboard primitive surface based on the angle parameter, determine the vertex coordinates of the billboard primitive surface based on the set size and the coordinates of the perspective projection point,
The drawing unit
A program for drawing a billboard primitive surface specified by the obtained vertex coordinates. In any one of Claims 1 thru | or 7,
The parameter calculation unit is
A program characterized in that the virtual normal vector is rotated based on a camera rotation matrix of a virtual camera, and the Z component of the rotated virtual normal vector is sign-inverted and obtained as the angle parameter.   A computer-readable information storage medium, wherein the program according to any one of claims 1 to 8 is stored. An image generation system for generating an image visible from a virtual camera in an object space,
An object space setting unit configured to place and set a plurality of objects including a lighting object in the object space;
A virtual camera control unit for controlling the virtual camera;
A virtual normal vector information storage unit that stores information on a virtual normal vector for a lighting effect set at each point of the lighting object;
A parameter calculation unit for obtaining an angle parameter indicating the magnitude of an angle formed by the visual line direction vector and the virtual normal vector of the virtual camera based on the virtual normal vector information;
A billboard setting unit configured to set at least one of a size, α value, luminance, brightness, and saturation of a billboard primitive surface for a lighting effect arranged and set to face the virtual camera based on the angle parameter; ,
An image generation system comprising: a drawing unit that draws the billboard primitive surface.