JP2007164323A - 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 for expressing a state of changes of thunder in real time with a small processing load. <P>SOLUTION: In generating a new parts object POB, the power parameter P of the previously generated parts object POB is attenuated, and the size of the newly generated parts object POB is determined based on the attenuated power parameter P. A parameter C for branch determination is prepared, and branch parts generation processing for generating a plurality of new parts objects POB to be linked to the previously generated parts object POB is operated under such conditions that the parameter C exceeds a threshold Cth. The branch parts generation processing is operated by distributing the power parameters P of the parts object POB at the branch origin according to the distribution rate. <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 an object such as a character is set is known. It is very popular for experiencing so-called virtual reality. For example, an image generation system that generates a game image of an action game in which the player moves the object space by operating the character or causes the character to take some action. It is preferable that a natural phenomenon such as lightning can be expressed realistically.

  By the way, as a method of expressing lightning, there is a method of preparing multiple textures that depict how lightning swells and changing, drawing polygons with textures attached while replacing multiple textures Conventionally known. However, this method has a problem that lightning changes become a pattern and lacks realism of expression, and a large number of textures must be prepared, resulting in an increase in memory consumption.

In addition, in order to more realistically represent how lightning changes, there is also a method of finding an interpolation curve in real time from a certain control point using a function and generating an object that represents lightning based on the obtained interpolation curve. . However, the method for obtaining such an interpolation curve can reduce the data to be prepared in advance, but it requires a complicated calculation process to eliminate the pattern of the interpolation curve by the function, so that the object drawing process is delayed. Therefore, there is a risk that the frame will not be updated in time.
JP 2002-42166 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a program, an information storage medium, and an image generation system that can express how lightning changes in real time with a small processing load.

  (1) The present invention is an image generation system for generating an image, an object generation unit that generates a lightning object in which a plurality of part objects are connected, and an object that sets the generated lightning object in an object space A space setting unit, and a drawing unit that generates an image viewed from a given viewpoint in the object space, wherein the object generation unit sequentially generates the plurality of part objects from a given reference part object, The present invention relates to an image generation system that determines at least one of the size, shape, and number of a newly generated part object according to a power parameter set for the reference part object. The present invention also relates to a program that causes a computer to function as each of the above-described units and an information storage medium that stores such a program.

  According to the present invention, the size of the part object and the number of generated part objects are determined according to the power parameter set for the reference part object. For example, the power parameter is changed according to the lightning occurrence state. For example, it is possible to represent the change of lightning in real time with a relatively small processing load.

  (2) In the image generation system, the program, and the information storage medium of the present invention, the object generation unit changes the power parameter set for the reference part object, based on the changed power parameter, It is also possible to determine at least one of the size and shape of a newly generated part object. The power parameter may be attenuated every time a part object is generated, or may be increased every time a part object is generated. For example, if the power parameter is attenuated as in the former, the size of the newly generated part object is determined based on the attenuated power parameter while attenuating the power parameter set for the reference part object. By doing so, it is possible to realistically express how lightning light weakens as it moves away from the point of occurrence of lightning. Further, for example, if the power parameter is increased as in the latter case, it is possible to realistically express how lightning light becomes stronger as it moves away from the point of occurrence of lightning.

  (3) In the image generation system, the program, and the information storage medium of the present invention, the part object is a polygon polygon, and the object generation unit has at least a size and a shape of the polygon polygon based on a power parameter. One may be determined. For example, a part object may be a rectangular polygon, and the width may be determined based on the power parameter while attenuating and changing the power parameter. In this way, since the part objects generated in order from the reference part object become thinner as the power parameter decays, it is possible to realistically represent how the lightning becomes thinner as it moves away from the lightning point. Can do.

  (4) In the image generation system, the program, and the information storage medium of the present invention, the object generation unit acquires a random value every time the part object is generated, and performs a process of accumulating the acquired random number value. When the cumulative value exceeds the threshold value, a plurality of part objects connected to the previously generated part object may be newly generated. In this way, since the opportunity to generate a plurality of part objects that branch from one part object is randomly given, it is difficult to pattern the shape of the lightning object.

  (5) In the image generation system, program, and information storage medium of the present invention, when the object generation unit newly generates a plurality of part objects connected to the previously generated part object, the previously generated part object The size of multiple part objects branched from the previously generated part object based on the distributed power parameters May be determined. In this case, for example, if the distribution ratio of the power parameter is changed, the pattern property of the shape of the lightning object can be eliminated.

  (6) In the image generation system, program, and information storage medium of the present invention, when the object generation unit generates each part object while changing the attenuation of the power parameter, the attenuated power parameter is a predetermined value. You may make it complete | finish the production | generation process of a part object on condition that it fell below the threshold value.

  (7) In the image generation system, the program, and the information storage medium of the present invention, the object generation unit ends the part object generation process on condition that the leading edge of the lightning object reaches a predetermined position in the object space. You may do it.

  (8) In the image generation system, the program, and the information storage medium of the present invention, the object generation unit performs the part object generation process on the condition that the number of part objects constituting the lightning object has reached a predetermined number. You may make it complete | finish.

  (9) The present invention is also an image generation system for generating an image, wherein an object generation unit that generates a lightning object in which a plurality of part objects are connected, and the generated lightning object is set in an object space. An object space setting unit; and a drawing unit that generates an image viewed from a given viewpoint in the object space, wherein the object generation unit sequentially generates the plurality of part objects from a given reference part object. The present invention relates to an image generation system that performs a process of changing the number of generated part objects according to the size of a power parameter set for the reference part object. The present invention also relates to a program that causes a computer to function as each of the above-described units and an information storage medium that stores such a program.

  According to the present invention, since the number of generated part objects varies depending on the size of the power parameter set for the reference part object, the size of the lightning as a whole, the state of lightning splitting, etc. differ depending on the situation. Realistic lightning can be expressed.

  (10) In the image generation system, the program, and the information storage medium of the present invention, the object generation unit randomly determines the direction of each part object, and the variable range of the direction of the reference part object is another part object. You may make it become smaller than the variable range of direction. In this way, it is possible to eliminate the inconvenience that lightning light tends to be extremely unnatural.

  (11) In the image generation system, the program, and the information storage medium of the present invention, the object generation unit performs a process of correcting the randomly determined direction of the part object so as to be directed to the target point in the object space. It may be. In this way, it is possible to represent a state in which lightning is moving toward the target point as a whole while randomly determining the orientation of the part object.

  (12) In the image generation system, the program, and the information storage medium of the present invention, the object generation unit is at least one of the size, shape, number of generations, branch probability, direction variable range, and color of the part object. The lightning object may be generated by changing one according to an event occurring in the object space. In this way, for example, when the present invention is applied to a game, the state of lightning expressed in accordance with an event that occurs based on the progress of the game, an event that occurs based on the player's operation, etc. Because it can be changed, convenience is enhanced.

  (13) In the image generation system, the program, and the information storage medium of the present invention, when the drawing unit draws the lightning object, the drawing unit performs a process of mapping a given texture to each part object. You may make it change dynamically the color distribution of the texture mapped with respect to an object. In this case, textures having different color distributions may be dynamically generated, or a plurality of textures having different color distributions may be prepared in advance and the texture to be used may be dynamically switched. In this way, appropriate expression can be performed according to the lightning occurrence situation and the like, and convenience is enhanced.

  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.

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

  The operation unit 160 is for a player to input operation data of a player object (an example of a moving object, a player character operated by the player), and functions thereof are a lever, a button, a steering, a microphone, and a touch panel display. Alternatively, it can be realized by 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 main storage unit 172 in the storage unit 170 as a work area. The functions of the processing unit 100 can be realized by hardware such as various processors (CPU, DSP, etc.), ASIC (gate array, etc.), and programs.

  The processing unit 100 includes an object space setting unit 110, a movement / motion processing unit 112, a virtual camera control unit 114, an object generation unit 116, a drawing unit 120, and a sound generation unit 130. Note that some of these may be omitted.

  The object space setting unit 110 is an object composed of various objects (polygons, free-form surfaces, subdivision surfaces, etc.) representing display objects such as characters, buildings, stadiums, cars, trees, pillars, walls, and maps (terrain). ) Is set in the object space. In other words, the position and rotation angle of the object in the world coordinate system (synonymous with direction and direction) are determined, and the rotation angle (rotation angle around the X, Y, and Z axes) is determined at that position (X, Y, Z). Arrange objects. Particularly in this embodiment, the object data of the lightning object generated by the object generation unit 116 is written in the object data storage unit 176 of the storage unit 170, and the generated lightning object is arranged and set in the object space in real time. I do.

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

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

  For example, when an object (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 object generation unit 116 performs a process of generating a lightning object in which a plurality of part objects are connected. The lightning object is an object for expressing lightning light branched by connecting a part object composed of rectangular polygons with one or more other part objects.

  The object generation unit 116 generates a lightning object by generating a plurality of part objects in order from a given reference part object. At this time, the size of the part object, specifically, the width of the rectangular polygon is determined based on the power parameter. When a new part object is generated, the power parameter given to the previously generated part object is multiplied by a given attenuation factor to attenuate the power parameter each time the part object is generated. I do. The initial value of the power parameter can be determined randomly, and the initial value corresponds to the width of the reference part object that is generated first.

  In addition, the object generation unit 116 acquires a random value every time a part object is generated, and performs processing for accumulating the acquired random number value. The accumulated random number is used for the lightning branching process. For example, when the accumulated value exceeds a threshold value, a plurality of part objects connected to the previously generated part object are newly generated. Further, when branching is performed, the power parameter of the previously generated part object is distributed to a plurality of newly generated part objects at a given ratio. That is, the sizes of a plurality of part objects branched from the previously generated part object are determined based on the distributed power parameters. The threshold value may be fixed, but may be changed. By changing the threshold, it is possible to change the state of lightning light branching (number of branches and branching pattern). Further, when changing the threshold value, it may be changed in units of lightning objects, or may be changed in the process of generating one lightning object. The threshold value may be changed according to the initial value of the power parameter set for the reference part object.

  The object generation unit 116 ends the generation of a new part object when a predetermined generation end condition is satisfied. For example, the power parameter attenuation state, the number of components of the lightning object, the size of the lightning object, and the like can be used as criteria for determining the generation end condition. For example, if the generation of a part object is terminated according to the power parameter attenuation state, the number of generated part objects can be varied according to the size of the power parameter set for the reference part object. Can do. A plurality of conditions can be set as the generation end condition. In this case, when any of the plurality of generation end conditions is satisfied, the generation of a new part object is ended. May be.

  The object generation unit 116 randomly determines the direction of each generated part object. At this time, the variable range of the direction of the reference part object is set smaller than the variable range of the direction of the other part objects. This eliminates the inconvenience that lightning is directed in a strange direction and an unnatural image is formed. When the destination of lightning (target point) is determined, the direction of the randomly determined part object can be corrected so as to be directed to the target point in the object space. For example, the target point may be determined by position coordinates in the world coordinate system, and the target point may be set for an object arranged in the object space. The target point may be fixed or moved in the object space.

  The drawing unit 120 performs drawing processing based on the results of various processing (game processing) performed by the processing unit 100, thereby generating an image and outputting the image to the display unit 190. When generating a so-called three-dimensional game image, first, object data (model data) including vertex data (vertex position coordinates, texture coordinates, color data, normal vector, α value, etc.) of each vertex of the object (model) ) Is input, and vertex processing is performed based on the vertex data included in the input object data. When performing the vertex processing, vertex generation processing (tessellation, curved surface division, polygon division) for re-dividing the polygon may be performed as necessary. In vertex processing, geometry processing such as vertex movement processing, coordinate transformation (world coordinate transformation, camera coordinate transformation), clipping processing, perspective transformation, or light source processing is performed, and an object is configured based on the processing result. Change (update, adjust) the vertex data given for the vertex group. 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 (fragment processing) for drawing pixels constituting an image (fragments constituting a display screen) is performed. In pixel processing, various processes such as texture reading (texture mapping), color data setting / changing, translucent composition, anti-aliasing, etc. are performed to determine the final drawing color of the pixels that make up the image, and perspective transformation is performed. The drawing color of the object is output (drawn) to the drawing buffer 174 (buffer that can store 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. Thereby, an image that can be seen from the virtual camera (given viewpoint) set in the object space is generated. Note that when there are a plurality of virtual cameras (viewpoints), an image can be generated so that an image seen from each virtual camera can be displayed as a divided image on one screen.

  The vertex processing and pixel processing performed by the drawing unit 120 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). May be. Programmable shaders can be programmed with vertex-level processing and pixel-level processing, so that the degree of freedom of rendering processing is high, and the expressive power can be greatly improved compared to fixed rendering processing by hardware. .

  The drawing unit 120 performs geometry processing, texture mapping, 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, object data (positional coordinates of object vertices, texture coordinates, color data (luminance data), normal vector, α value, etc.) after geometry processing (after perspective projection conversion) is stored in the main storage unit 172. The

  Texture mapping is a process for mapping a texture (texel value) stored in the texture storage unit 178 of the storage unit 170 to an object. Specifically, the texture (surface properties such as color (RGB) and α value) is read from the texture storage unit 178 of the storage unit 170 using the texture coordinates set (given) at the vertex of the object. Then, a texture that is a two-dimensional image is mapped to an object. In this case, processing for associating pixels with texels, bilinear interpolation or the like is performed as texel interpolation. In particular, in this embodiment, when drawing a lightning object, a process of mapping a given texture to each part object may be performed. In this case, the texture color distribution (texel pattern) mapped to the part object can be dynamically changed. In this case, textures having different color distributions may be dynamically generated, or a plurality of textures having different color distributions may be prepared in advance and the texture to be used may be dynamically switched. Further, the texture color distribution may be changed in units of part objects constituting one lightning object, or the texture color distribution may be changed in units of lightning objects.

  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). For example, in normal α blending, a process for obtaining a color obtained by combining two colors by performing linear interpolation with the α value as the strength of synthesis is performed.

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

  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. In this embodiment, as shown in FIGS. 2A and 2B, different thunder objects LOB are generated in real time and drawn to generate different thunders every time. A technique to express the situation is adopted.

  In this embodiment, as shown in FIG. 3, a celestial sphere object that moves following the virtual camera VC is set in the object space, and the lightning object LOB is projected on the projection plane set in the distant view area in the celestial sphere object. By drawing a scene that can be seen from the virtual camera VC, an image as shown in FIGS. 2A and 2B is generated.

  The lightning object LOB is an object formed by connecting a plurality of part objects POB0 to POB9 as shown in FIG. That is, one or a plurality of part objects are connected to each part object. Each part object is generated in order from the reference part object POB0. In addition, the part object is generated for each line with respect to the lines L1 to L4. When the generation end condition for the part object is determined for each line and the generation end condition for the part object is satisfied for all the lines, the lightning object LOB is Complete. That is, the lightning object LOB can be said to be an assembly of line-shaped part objects in which a plurality of part objects POB are connected.

  FIG. 5A shows an example of the part object POB. The part object POB is composed of a rectangular plate-shaped polygon composed of vertices V1 to V4, and the width component (thickness of lightning light) is obtained based on a power parameter P indicating the intensity of lightning. The length component of the polygon (lightning light length) is obtained by adding an adjustment length D2 obtained randomly using a random number to the basic length D1 fixedly determined in advance. By doing so, the basic length D1 can be obtained as the length component of the polygon even when the adjustment length obtained at random becomes zero.

  In addition, a lightning color (for example, yellow or white) is set for each vertex V1 to V4 of the part object POB. Moreover, transparency (α value) may be set for each vertex V1 to V4 of the POB of the part object. For example, the lightning color of the part object arranged at a position farther from the generation point becomes lighter. The transparency set for the vertices V1 to V4 may be changed.

  Note that instead of setting the vertex colors of the vertices V1 to V4 of the part object, the texture TEX as shown in FIG. Good. The texture TEX has a texel pattern (color distribution) that changes in gradation so that the inner side is yellow (first color) and the outer side approaches white (second color). With such a texel pattern, it can be shown that the lighter the lighter the stronger the yellow.

  Note that the texel pattern can be dynamically changed according to the occurrence of lightning, such as textures TEX2 to TEX4, in addition to the standardly used texture TEX0 shown in FIG. If the part object branches by shifting the yellow part to the left or right as in textures TEX2 and TEX4, the texture TEX2 is mapped to the part object that branches to the left, and the part object that branches to the right On the other hand, by mapping the texture TEX4, it is possible to show the state of lightning branching more clearly. Further, the yellow portion may be made narrower than the texture TEX0 as in the texture TEX3. In this way, when it is desired to extremely weaken the intensity of lightning, a visual effect can be obtained as if the size was changed afterwards without being affected by the size of the part object.

  Next, a method for generating the lightning object LOB will be described in more detail with reference to FIG.

  First, a reference part object POB0 arranged at a lightning occurrence point is generated. At this time, the initial value of the power parameter obtained at random is set as the width P0 of the reference part object POB0. In the present embodiment, a random number value is acquired every time a part object is generated, and it is determined whether or not to divide thunder lightning by accumulating these random number values. Specifically, a threshold value Cth for branch determination is prepared, and the cumulative value C of the random value Cn acquired every time a part object is generated satisfies C> Cth. Thunder lightning is split by generating multiple connected parts objects. In the example shown in FIG. 6, as a result of acquiring the random value C0 for the reference part object POB0, the cumulative value C of the acquired random values does not exceed Cth, so it is determined that no branching occurs.

  Subsequently, when generating the part object POB1 connected to the reference part object POB0, the power parameter is attenuated to determine the width P1 of the part object POB1. Specifically, the width P1 of the part object POB1 generated this time is obtained by multiplying the width P0 of the part object (basic part object POB0) generated last time by the attenuation rate A1 obtained at random. As described above, in the method of the present embodiment, a parent-child relationship is established between the part objects constituting the lightning object LOB, and the child parts are based on the size information (power parameter: width of the rectangular polygon) of the parent part object. You are looking for object size information. More specifically, the size information of the child part object is obtained by multiplying the size information of the parent part object by the attenuation rate (decrease rate of the width of the rectangular polygon). It is possible to generate a lightning object LOB that appears to have weak power.

  Also, when generating the part object POB1, the branch determination random value C1 is acquired, and it is determined whether or not the cumulative value C (= C0 + C1) of the random number acquired so far exceeds the threshold value Cth. . In the example shown in FIG. 6, it is determined that the branch is not taken because the threshold value Cth is not yet exceeded.

  In this way, when the part objects are generated in order while the power parameter corresponding to the polygon width P is attenuated, the cumulative value C of the random values acquired every time the part object is generated exceeds the threshold value Cth. The case will come. In the example shown in FIG. 6, the accumulated value C exceeds Cth by accumulating the random value C2 acquired when the part object POB2 is generated. As a result, a plurality of new part objects POB3 and POB4 are generated so as to branch from the part object POB2. At this time, the widths P3 and P4 of the part objects POB3 and POB4 are determined as follows.

  First, after multiplying the width P2 of the previously generated part object by the attenuation rate A3, the multiplication result (P2 × A3) is multiplied by the distribution rates B1 and B2 (for example, B1 + B2 = 1), The widths P3 (= P2 × A3 × B1) and P4 (= P2 × A4 × B2) of the part objects POB3 and POB4 are obtained.

  In the same way, every time a part object is generated, the size of the part object is determined while a parameter corresponding to the width (power parameter) is attenuated, and each time a part object is generated, a random value is accumulated to branch. The lightning object LOB is generated by determining whether or not to make it occur.

  In the method of the present embodiment described above, random values are accumulated every time the part object POB is generated, and whether or not lightning light is branched is determined based on the accumulated value C. As a result, various types of lightning can be freely generated according to how the threshold value Cth is set.

  For example, if the threshold value Cth is set large, a lighter lightning object LOB with a relatively thick lightning light can be generated as shown in FIG. 7A, and if the threshold value Cth is set small, the threshold value Cth shown in FIG. As shown in B), it is possible to generate a lightning object LOB of lightning light that is finely branched. Further, the threshold value Cth may be changed in the generation process of the lightning object LOB. For example, if the threshold value Cth is gradually lowered every time a new part object is generated, the threshold value Cth is changed to FIG. As shown in FIG. 4, it is possible to generate a lightning object LOB that is thick lightning near the point of occurrence of lightning, but that branches finely toward the end. Thus, the threshold value Cth for determining the branching of lightning light can be set according to the type of lightning to be expressed, and may be changed according to time, weather, etc. When expressing the state of the attack, it can be changed according to various conditions such as the strength and type of the attack or the strength and type of the character.

In the present embodiment, the orientation of the part objects constituting the lightning object LOB is randomly determined using random numbers. However, the angle range in which the direction is variable is changed between the reference part object and the other part objects. Specifically, as shown in FIG. 8, the variable angle range θ _{0 in} the direction of the reference part object POB0 is set to be smaller than the variable angle range θ _{N in} the direction of another part object POBN (N ≧ 1). Yes. By doing so, the direction of lightning is directed in a strange direction from the point of occurrence, for example, an unnatural image is generated in which lightning falling from the sky is directed in a direction other than the ground surface Is preventing.

  The method of determining the orientation of the part object is not limited to the above-described example, and the following method can also be adopted.

  For example, it is possible to generate a lightning object LOB that goes from a lightning occurrence point to a target point in real time. In this case, as shown in FIG. 9, the unit vector Vec1 (first vector) having the origin point as the starting point and the direction component of the reference part object POB0 as the direction component, and the direction from the origin point to the target point An angle correction vector (angle correction matrix) is obtained based on the inner product Vec1 · Vec2 (= cosω) with the unit vector Vec2 (second vector) having components, and the direction of the randomly determined part object is angle corrected. You may make it correct | amend by a vector. In this way, as shown in FIG. 10, it is possible to express a situation in which the lightning object LOB generated in the sky is guided to the tall tree object WOB.

  When a target point is set, the correction amount (the magnitude of the angle correction vector) may be changed according to the positional relationship between the part object and the target point. For example, the correction amount can be increased as the part object located at the end of lightning approaches the target point. Further, as a method for producing the same effect, the variable range of the direction determined at random by a random number may be reduced as the part object located at the end of the lightning approaches the target point.

  The target point may be set according to an operation performed by the player, or may be automatically set by software using a predetermined algorithm. For example, when expressing a case where the player character attacks the enemy character with lightning, the player operates the game controller to specify the attack direction of the player character or the enemy character to be attacked by the player character. A method of setting a target point can be adopted. Also, for example, when expressing a lightning strike on a tree or tall building, obtain the height information of the tree object or building object in the object space and set the target point for the tallest object. It is possible to adopt such a method.

  The lightning object generation method of the present embodiment described above has the following characteristics, and realistically expresses how lightning light diverges randomly as it moves away from the point of occurrence of lightning. Can do.

  First, when generating a new part object, the power parameter of the previously generated part object is attenuated, and the size of the newly generated part object is determined based on the attenuated power parameter. In other words, the power parameter given to the part object is attenuated as the distance from the lightning point increases. Specifically, when a part object is newly generated, the size is reduced by multiplying the power parameter given to the previously generated part object by a parameter A corresponding to the attenuation rate (decrease rate of the width of the rectangular polygon). Yes.

  Next, a branch part generation process for generating a plurality of new part objects connected to the previously generated part object on condition that the parameter C for branch determination is prepared and the parameter C exceeds the threshold value Cth is performed. Do. The parameter C is a cumulative value of random numbers and is a cumulative value of random numbers acquired when generating a part object.

  In addition, when the lightning is branched, a parameter B corresponding to a distribution ratio that determines at what ratio the power parameter is distributed from the branch source part object is used. In the branch part generation process, the power parameter of the branch source part object is distributed to a plurality of branch destination part objects according to the randomly obtained distribution ratio.

  Further, the generation of a new part object can be ended based on the part object generation end condition. The generation end condition is determined for each line for generating a part object. For example, when the power parameter falls below a threshold value, when the number of part objects constituting the lightning object reaches a predetermined number, or at the bottom The case where the part object at the position reaches a predetermined position such as the ground surface can be set as the generation end condition.

  The direction of the part object is determined by a random number, but when the target point is set, the direction of the part object determined at random by the random number may be corrected.

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

  FIG. 11 is a flowchart illustrating a processing example when generating a lightning image.

  First, when a lightning event occurs (Y in step S1), a lightning object is generated (step S2). Next, the generated lightning object is set in the object space (step S3), and an image expressing a lightning strike is generated by drawing the lightning object (step S4).

  12 and 13 are flowcharts illustrating an example of lightning object generation processing.

  First, an initial value P0 of the power parameter P is obtained from a random number, and the width of the rectangular polygon serving as the reference part object is set (step S10).

  Next, the length (D1 + D2) of the rectangular polygon is determined by adding the adjustment length D2 obtained randomly with a random number to the predetermined basic length D1 (step S11). Next, the direction of the rectangular polygon is determined within a given angle range using random numbers (step S12). This completes the part object.

  Next, a random number value for branch determination is acquired and accumulated (step S13), and it is determined whether or not the accumulated value C exceeds the threshold value Cth (step S14).

  If the accumulated value C exceeds the threshold value Cth (Y in step S14), a branch line is generated. When generating a polygon for a branch line (Y in step S15), the power parameter P corresponding to the width of the previously generated rectangular polygon is attenuated by the attenuation factor A and distributed by the distribution factor B to generate the previous time. The width (P = P × A × B) of the rectangular polygon for the branch line among the plurality of rectangular polygons connected to the rectangular polygon is determined (step S16). Thereafter, the processing after step S11 is continued for each branched line.

  On the other hand, when the accumulated value C falls below the threshold value Cth (N in step S14), the power parameter P corresponding to the width of the previously generated rectangular polygon is attenuated by the attenuation factor A and the next generated rectangular polygon. (P = P × A) is determined (step S17).

  When the power parameter P for determining the width of the rectangular polygon falls below a given threshold (Y in step S18), the total number of generated rectangular polygons reaches a predetermined number (Y in step S19). Or, when any of the cases where the rectangular polygon located at the tip reaches the position (surface) corresponding to the ground surface of the object space (Y in step S20) is satisfied, the generation of the new rectangular polygon is terminated. Finish the generation of lightning lines. In this way, it is determined whether or not the generation of a new rectangular polygon is finished for each line, and when the generation of a new rectangular polygon is completed for all the lines, the lightning object is completed.

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 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.

  The present invention is not limited to that described in the above embodiment, and various modifications can be made. For example, terms cited as broad or synonymous terms in the description in the specification or drawings can be replaced with broad or synonymous terms in other descriptions in the specification or drawings.

  The lightning object generation method is not limited to that described in the above embodiment, and a method equivalent to the above method may be used.

  In the above embodiment, the case where the width of the polygon is changed by the power parameter P has been described, but both the width and length of the polygon may be changed by being influenced by the power parameter P. Alternatively, the length of the polygon may be fixed, and only the width of the polygon may be changed by the power parameter P. Various random numbers used when generating the part object may be acquired individually for setting each parameter, or a common random number may be acquired.

  In the above embodiment, the part object is configured by a rectangular polygon. However, the polygon object may not be a rectangular polygon as long as it is a polygonal polygon. In this case, the size and shape of the polygon can be determined by adjusting the distance between vertices constituting the polygon according to the power parameter.

  In the above-described embodiment, a method is adopted in which the power parameter is gradually attenuated every time the part object is generated. However, the power parameter may be changed to gradually increase. For the lines sequentially connected from the reference part object (line L1 in FIG. 4), the part object is generated without changing (attenuating or increasing) the power parameter, and the branch lines (lines L2 to L4 in FIG. 4) are generated. The part object may be generated while changing (attenuating or increasing) the power parameter. In this way, the branch line is generated in a range where the total number of parts that make up the lightning object does not have an excessive influence on the drawing process, and the main line of lightning light surely reaches the ground surface and the target point. Will be able to express the thunder.

  In addition, the lightning object may be generated by changing at least one of the size, shape, number of generations, probability of branching, variable range of orientation, and color according to the event occurring in the object space. Good. In this way, for example, when the present invention is applied to a game, the state of lightning expressed in accordance with an event that occurs based on the progress of the game, an event that occurs based on the player's operation, etc. Because it can be changed, convenience is enhanced. For example, when the size or shape of a part object is changed according to an event, the power parameter change rate (attenuation rate, increase rate) for each part object, and distribution of the power parameter that is multiplied each time the line branches It is possible to change the rate, the change rate of the power parameter for each part object generation line, the initial value of the power parameter set for the reference part object, and the like according to the event.

  The present invention can be applied to various games (action game, racing game, fighting game, shooting game, robot battle game, sports game, competition game, role playing game, simulation game, music playing game, dance game, etc.). The present invention is also applicable 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 functional block diagram of the image generation system of this embodiment. 2A and 2B are examples of images generated using the method of the present embodiment. The figure for demonstrating the method of this embodiment. A configuration example of a lightning object. Example configuration of part object. The figure for demonstrating the production | generation method of a lightning object. FIG. 7A to FIG. 7C are examples of lightning objects generated by the method of this embodiment. The figure for demonstrating the production | generation method of a lightning object. The figure for demonstrating the production | generation method of a lightning object. The example of the image produced | generated using the method of this embodiment. The flowchart which shows the example of the process of this embodiment. The flowchart which shows the example of the process of this embodiment. The flowchart which shows the example of the process of this embodiment. An example of a hardware configuration.

Explanation of symbols

LOB lightning object POB part object, POB0 standard part object,
100 processing unit,
110 Object space setting unit, 112 Movement / motion processing unit,
114 virtual camera control unit, 116 object generation unit,
120 drawing units, 130 sound generation units,
160 operation unit, 170 storage unit, 172 main storage unit, 174 drawing buffer,
176 Object 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 (16)

A program for generating an image,
An object generation unit for generating a lightning object in which a plurality of part objects are connected;
An object space setting unit for setting the generated lightning object in the object space;
As a drawing unit that generates an image viewed from a given viewpoint in the object space,
Make the computer work,
The object generation unit
The plurality of part objects are generated in order from a given reference part object,
A program for determining at least one of a size, a shape, and a number of a newly generated part object according to a power parameter set for the reference part object. In claim 1,
The object generation unit
A program for determining at least one of a size and a shape of a newly generated part object based on the changed power parameter while changing a power parameter set for the reference part object. In claim 1 or 2,
The part object is a polygonal polygon,
The object generation unit
A program for determining at least one of a size and a shape of the polygonal polygon based on a power parameter. In any one of Claims 1-3,
The object generation unit
Every time the part object is generated, a random number value is obtained, and the obtained random number value is accumulated,
A program characterized by newly generating a plurality of part objects connected to a previously generated part object when the accumulated value exceeds a threshold value. In claim 4,
The object generation unit
When newly generating multiple part objects that are linked to the previously generated part object,
The power parameter of the previously generated part object is distributed at a given rate to the newly generated part objects.
A program for determining a size of a plurality of part objects branched from a previously generated part object based on a distributed power parameter. In any one of Claims 1-5,
The object generation unit
A program characterized in that when each part object is generated while the power parameter is attenuated, the part object generation process is terminated on condition that the attenuated power parameter falls below a predetermined threshold value. In any one of Claims 1-6,
The object generation unit
A program for ending a part object generation process on condition that the leading edge of the lightning object reaches a predetermined position in an object space. In any one of Claims 1-7,
The object generation unit
A program for ending a part object generation process on condition that the number of part objects constituting the lightning object has reached a predetermined number. A program for generating an image,
An object generation unit for generating a lightning object in which a plurality of part objects are connected;
An object space setting unit for setting the generated lightning object in the object space;
As a drawing unit that generates an image viewed from a given viewpoint in the object space,
Make the computer work,
The object generation unit
The plurality of part objects are generated in order from a given reference part object,
A program for performing a process of varying the number of part objects to be generated in accordance with the size of a power parameter set for the reference part object. In any one of Claims 1-9,
The object generation unit
Randomly determine the orientation of each part object,
A program characterized in that the variable range of the direction of the reference part object is smaller than the variable range of the direction of the other part object. In claim 10,
The object generation unit
A program for performing a process of correcting a randomly determined direction of a part object so as to be directed to a target point in an object space. In any one of Claims 1-11,
The object generation unit
The lightning object is generated by changing at least one of the size, shape, number of generations, branching probability, variable range of orientation, and color of the part object according to an event occurring in the object space. Program. In any one of Claims 1-12,
The drawing unit
When drawing the lightning object, perform a process of mapping a given texture to each part object,
A program that dynamically changes the color distribution of a texture mapped to a part object.   An information storage medium readable by a computer, wherein the program according to any one of claims 1 to 13 is stored. An image generation system for generating an image,
An object generator for generating a lightning object in which a plurality of part objects are connected;
An object space setting unit for setting the generated lightning object in the object space;
A drawing unit for generating an image viewed from a given viewpoint in the object space;
Including
The object generation unit
The plurality of part objects are generated in order from a given reference part object,
An image generation system, wherein at least one of a size, a shape, and a number of a newly generated part object is determined according to a power parameter corresponding to the width of the reference part object. An image generation system for generating an image,
An object generation unit for generating a lightning object in which a plurality of part objects are connected;
An object space setting unit for setting the generated lightning object in the object space;
A drawing unit for generating an image viewed from a given viewpoint in the object space;
Including
The object generation unit
The plurality of part objects are generated in order from a given reference part object,
An image generation system characterized in that processing for varying the number of generated part objects is performed in accordance with the magnitude of a power parameter set for the reference part object.