JP4651436B2 - Program, information storage medium, and image generation system - Google Patents

Description

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

  Conventionally, an image generation system (game system) that generates an image that can be viewed from a virtual camera (a given viewpoint) in an object space (virtual three-dimensional space) in which an object such as a character is set is known. It is very popular for experiencing so-called virtual reality.

  In such an image generation system, in order to enhance the virtual reality of the player, it is desirable to be able to realistically express how snow, ash, and the like accumulate, for example. However, in the prior art, in order to realistically represent a model in which the deposition amount changes from moment to moment, it was necessary to prepare model data for deposit representation for each mode of change. If the real-time property of the change in the deposition amount is pursued, the amount of model data prepared in advance becomes enormous, which is not realistic.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a program, an information storage medium, and an image generation system capable of realistically expressing a quantitative change in deposits with a small amount of data. It is in.

  (1) The present invention is an image generation system for generating an image, wherein an event determination unit that determines whether or not a deposition event in which a deposition amount of a deposit increases in an object space has occurred, and the deposition event When it is determined that the object has occurred, vertex shading is performed to change the vertex data of the original object of the deposit model, and the object space is viewed from a given viewpoint based on the vertex data after the vertex shading. An image generation unit that generates a vertex shading that moves the vertices of the original object of the deposit model in the deposition direction based on the vertex movement information that fluctuates over time. Related to image generation system. 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 an information storage medium that can be read by a computer, and stores (records) a program that causes the computer to function as each of the above-described units.

  The vertex movement information is a parameter that determines the amount of movement of the vertices constituting the object and the movement direction of the vertices, and can be defined as a function having time as an argument, for example.

  Further, the deposition direction means a direction in which the amount of deposit increases, in other words, a direction in which the volume of the object increases. In addition, when referring to the reverse direction of the deposition direction, it is not necessary to be in the opposite direction of the deposition direction, as long as it is a direction in which the amount of deposited material decreases, in other words, a direction in which the volume of the object decreases. Means.

  According to the present invention, the original object of the deposit model is deformed with the passage of time, and an image showing how the accumulation amount increases is generated. For this reason, even when the viewpoint position and the line-of-sight direction are changed, it is possible to perform realistic expression that can grasp how the solid shape of the deposit is gradually changed. And since it is possible to generate an image in which the amount of deposits changes with the passage of time using a common source object, it is not necessary to prepare a large amount of model data in advance, thus saving memory usage Can do.

  (2) In the image generation system, the program, and the information storage medium of the present invention, height map data in which height information is set in a grid pattern is associated with the original object of the deposit model, The image generation unit obtains height information set in the grid points with reference to height map data associated with the original object of the deposit model, and the vertex movement information including the obtained height information Based on this, vertex shading may be performed in which the vertex of the original object of the deposit model is moved in the accumulation direction. In this way, the original object can be deformed by dynamically controlling the positions of the vertices constituting the object of the deposit model as the deposit amount increases with time.

  (3) In the image generation system, the program, and the information storage medium of the present invention, normal map data in which normal vector information is set in a grid pattern is associated with the original object of the deposit model. The image generation unit obtains normal vector information set at the grid points with reference to normal map data associated with the original object of the deposit model, and includes the obtained normal vector information Based on the vertex movement information, vertex shading that moves the vertex of the original object of the deposit model along the direction of the normal vector may be performed. Even in this case, the original object can be deformed by dynamically controlling the positions of the vertices constituting the object of the deposit model as the deposit amount increases with time.

  (4) In the image generation system, program, and information storage medium of the present invention, the event determination unit generates a contact event in which another object contacts the object of the deposit model whose vertex is moved in the deposition direction. Height map data in which height information is set in a grid pattern is associated with the other object, and the image generation unit is associated with the other object. The height information set for the grid point is acquired with reference to the height map data, and the vertex of the object of the deposit model is moved in the direction opposite to the deposition direction based on the acquired height information. Vertex shading may be performed. In this way, it is possible to realistically represent a state in which the object of the deposit model once deformed is depressed according to the shape of another object in contact therewith. In addition, when moving the vertex in the direction opposite to the deposition direction, it is not necessary to move the vertex in the direction opposite to the deposition direction, so that the deposit amount is reduced, in other words, the deposit model. The vertices may be moved so that the volume of the object decreases.

  (5) In the image generation system of the present invention, the event determination unit includes a first hit check area set for the object of the deposit model and a second hit check area set for the other object. It is determined that the contact event has occurred when the objects overlap, and when the vertex of the original object of the deposit model is moved in the deposition direction, or the object of the deposit part model whose vertex is moved in the deposition direction A hit check area setting unit may be included that resets the first hit check area based on the position of the apex after the movement when the apex is moved in a direction opposite to the accumulation direction. In the program and information storage medium of the present invention, the computer may function as the event determination unit and the hit check area setting unit. In this way, the influence of the change in the position of the deposition surface accompanying the increase or decrease in the amount of deposit can be reflected in the hit check.

  (6) The image generation system according to the present invention further includes a deposition restriction area setting unit that sets a deposition restriction area in the original object of the deposit model, and the image generation unit is configured for the original object of the deposit model. When the accumulation restriction area is set, vertex shading for restricting the movement of the vertex in the accumulation restriction area may be performed. In the program and the information storage medium of the present invention, a computer may function as the accumulation limited area setting unit and the image generation unit. In this way, for example, when expressing snow as sediment, an area close to the heat source is set as a volume restriction area so that snow does not accumulate in the high temperature area, and the event where snow accumulates is realistic. Can be expressed.

  (7) In the image generation system, the program, and the information storage medium of the present invention, when vertex shading is performed in which the image generation unit moves the vertex of the original object of the deposit model, You may make it perform the pixel shading which changes image information per pixel about the object of a deposit model. In this way, for example, when expressing snow as a deposit, image information such as pixel color, reflectance, and refractive index is changed to change the degree of light reflection according to the amount of snow piled up. It is possible to realistically represent an event where snow falls.

  (8) In the image generation system, the program, and the information storage medium of the present invention, when the deposition event ends, the image generation unit sets the vertex of the object of the deposit model in a direction opposite to the deposition direction. You may make it perform the vertex shading to move. In this way, for example, when snow is represented as a deposit, it is possible to realistically represent a state in which the snow has stopped falling and the snow has melted due to sunlight falling on the accumulated snow.

  (9) In the image generation system, the program, and the information storage medium of the present invention, the image generation unit is configured to store the original object of the deposit model based on the first vertex movement information during the occurrence of the accumulation event. The vertex is moved in the deposition direction, and after the deposition event is finished, the vertex of the object of the deposit model in which the vertex is moved in the deposition direction based on the second vertex movement information different from the first vertex movement information. Vertex shading that moves in the direction opposite to the deposition direction may be performed. In this way, for example, when expressing snow as a deposit, it is possible to represent the object realistically by changing the degree of deformation of the object depending on how the snow suddenly accumulates and how the accumulated snow gradually melts. .

  (10) In the image generation system, the program, and the information storage medium of the present invention, after the deposition event ends, image information is obtained in pixel units for the deposit model object whose vertex is moved in the direction opposite to the deposition direction. Pixel shading to be changed may be performed. In this way, for example, when snow is represented as a deposit, it is possible to realistically represent how the snow surface shines with snow melting water.

  (11) In the image generation system, the program, and the information storage medium of the present invention, the event determination unit generates a deposit movement event in which the deposit moves from the first area to the second area in the object space. In the first area, when the image generation unit determines that the deposit movement event has occurred, the vertex of the object of the deposit model is opposite to the deposition direction. In the second area, vertex shading for moving the vertex of the object of the deposit model in the deposition direction may be performed. In this way, it is possible to realistically represent how the deposit falls or slides down according to gravity.

  (12) In the image generation system, the program, and the information storage medium of the present invention, different vertex movement information is set in a plurality of areas that divide the original object of the deposit model, and the image generation unit You may make it perform the vertex shading which moves the vertex of the original object of a deposit model to a deposition direction based on the vertex movement information set for every said area. In this way, it becomes possible to realistically express the accumulation of deposits and the like.

  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 of a player object (player character operated by the player), and the function is realized by a lever, a button, a steering, a microphone, a touch panel display, or a casing. it can. 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.

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

  The processing unit 100 (processor) performs processing such as game processing, image generation processing, or sound generation processing based on operation data and programs from the operation unit 160. Here, as the game process, a process for starting a game when a game start condition is satisfied, a process for advancing the game, a process for placing an object such as a character or a map, a process for displaying an object, and a game result are calculated. There is a process or a process of ending a game when a game end condition is satisfied. The processing unit 100 performs various processes using the main storage unit 171 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 111, a movement / motion processing unit 112, a virtual camera control unit 113, an event determination unit 114, a hit check area setting unit 115, a deposition limit area setting unit 116, an image generation unit 120, and sound generation. Part 130. Note that some of these may be omitted.

  The object space setting unit 111 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. 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.

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

  The virtual camera control unit 113 performs a virtual camera (viewpoint) control process for generating an image that can be seen 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. When there are a plurality of virtual cameras (viewpoints), the above-described control process is performed for each virtual camera.

  The event determination unit 114 performs processing for determining whether or not a deposition event in which the amount of deposits increases in the object space has occurred, sets a deposition event occurrence flag based on the determination result, and gives a given The flag is stored in the storage buffer.

  In addition, the event determination unit 114 performs processing for determining whether or not a contact event (collision event) in which the object of the deposit model and another object contact (collision) has occurred, and based on the determination result, the contact Sets the event occurrence flag and stores the flag in a given storage buffer. Specifically, it is determined whether or not contact between objects occurs by hit check area (hit check (hit determination process) using a bounding volume and a bounding box). The first set for the object of the deposit model When hit check is performed based on the positional relationship between the hit check area and the second hit check area set for another model object, and the first hit check area and the second hit check area overlap. It is determined that a touch event has occurred.

  In addition, the event determination unit 114 performs a process of determining whether or not a deposit movement event (avalanche event or fall event) in which the deposit moves from the first area to the second area in the object space has occurred. Based on the determination result, a sediment movement event occurrence flag is set, and the flag is stored in a given storage buffer.

  The accumulation event, the contact event, or the deposit movement event may be generated in accordance with a program when a given condition is satisfied, or the player moves the character object by operating the character of the player. It may be generated on the basis of the intention.

  The hit check area setting unit 115 performs the deposition when the vertex shader 122, which will be described later, performs vertex shading that moves the vertices constituting the original object of the deposit model in the deposition direction or the vertex group is moved in the deposition direction. When vertex shading is performed to move the vertices that make up the object of the object model in the direction opposite to the deposition direction, the deposit model (original model object or vertex shading) is based on the position of the moved vertex group. The first hit check area set for the (subsequent object) is reset (updated). In this way, the influence of the change in the position of the deposition surface accompanying the increase or decrease in the amount of deposit can be reflected in the hit check.

  Specifically, the hit check area setting unit 115 has a maximum value and a minimum value for each component (X-axis component, Y-axis component, Z-axis component) of the vertex position coordinates with respect to the deposit model object whose vertex has been moved. And the position coordinates of the vertices constituting the object (volume) of a simplified shape such as a cube or a sphere containing the object are calculated from the maximum value and the minimum value, and the simplified object (volume) ) Is set as a new hit check area.

  The accumulation restriction area setting unit 116 performs processing for setting the accumulation restriction area in the original object of the deposit model. For example, the texture storage unit 175 of the storage unit 170 prepares a deposition limit area setting texture in which a deposition limit area and a non-deposition limit area are set according to texel color information (tone values) for the original object of the deposit model. deep. In the texture for setting the accumulation limit area, a low luminance value (including 0) is set as the texel color information in the accumulation limit area, and a higher luminance value is set as the texel color information in the non-deposition limit area. Keep it. In this way, at the time of vertex shading described later, by referring to the accumulation limit area setting texture and associating each vertex of the original model object of the deposit with the texel, for the vertices belonging to the accumulation restriction area, The deformation of the original model object can be restricted (or prohibited). As a method for setting the accumulation limit area, a given vertex movement amount determination parameter is set for each vertex, and in particular, a low value (including 0) is set for the vertex movement amount determination parameter for the accumulation limitation area. Can also be realized.

  The image generation unit 120 performs drawing processing based on the results of various processes (game processing) performed by the processing unit 100, thereby generating an image and outputting the image to the display unit 190. When generating a so-called three-dimensional game image, first, a vertex list including vertex data (vertex position coordinates, texture coordinates, color data, normal vector, α value, etc.) of each vertex of the object is input and input. Based on the vertex data included in the vertex list, vertex shading (vertex processing in a broad sense) is performed. When performing vertex shading, vertex generation processing (tessellation, curved surface division, polygon division) for subdividing a polygon can be performed as necessary. In vertex shading, according to the vertex shader program (first shader program in a broad sense), vertex movement processing, coordinate transformation (world coordinate transformation, camera coordinate transformation), clipping processing, or geometric processing such as perspective transformation is performed. On the basis of the processing result, the vertex data given to the vertex group constituting the object is changed (updated or adjusted). Then, rasterization (scan conversion) is performed based on the vertex data after vertex shading, and pixel shading (pixel processing and fragment processing in a broad sense) that draws pixels (fragments that configure the display screen) that constitute the display image Is done. In pixel shading, according to the pixel shader program (second shader program), various processes such as texture reading (texture mapping), color data setting / change, translucent composition, anti-aliasing, etc. are performed, and the final display image is displayed. The drawing color of the pixel is determined, and the drawing color of the perspective-transformed object is output (drawn) to the frame buffer 173 (buffer that can store image information in units of pixels, VRAM). That is, in pixel shading, per-pixel processing for setting or changing image information (color, normal, luminance, α value, etc.) for each pixel of a display image is performed. As a result, an image (frame image) that can be seen from the virtual camera (given viewpoint) in the object space is generated. In addition, when there are a plurality of virtual cameras (viewpoints), a frame image can be generated so that an image seen from each virtual camera can be displayed on one screen as a divided image.

  The image generation unit 120 includes a vertex shader unit 122 and a pixel shader unit 124. Note that some of these may be omitted.

  The vertex shader unit 122 is a type of programmable shader that performs vertex shading, which is processing performed in units of vertices. In particular, the vertex shader unit 122 receives the vertex data of the original object of the deposit model when the event determination unit 114 determines that a deposition event has occurred, that is, when the deposition event generation flag is set to ON. Perform vertex shading to change. Specifically, vertex shading is performed to move the vertices of the original object of the deposit model in the accumulation direction based on the vertex movement information that varies with time. That is, the position coordinates of the moved vertex are calculated based on the vertex movement information, and the vertex is moved to the obtained position coordinates. When the accumulation event ends, vertex shading that moves the vertex of the object of the deposit model in the direction opposite to the accumulation direction may be performed. Further, the amount and direction of movement of the vertex due to vertex shading may be changed during the occurrence of the accumulation event and after the end of the accumulation event.

  The vertex movement information includes information for determining the vertex movement amount and the vertex movement direction (movement angle). For example, the moving amount of the vertex and the moving direction of the vertex can be set by the image information (color component, luminance, normal line, etc.) of the texel constituting the texture. Such a texture may be a color image including all color components (R component, G component and B component), a gray scale image, or a single color component. It may be an image (R component image, G component image, B component image). Note that apex movement information different from other areas may be set in a given area of the original object of the deposit model. In this case, the vertex shader unit 122 performs vertex shading that moves the vertices of the original object of the deposit model in the accumulation direction based on the vertex movement information set for each area. In this way, it is possible to locally change the state of deposition, for example, to express a puddle.

  Then, the vertex shader unit 122 associates the texel and the vertex with reference to the texture, and acquires image information set in the texel corresponding to each vertex. This image information is changed (updated) over time. Then, based on the acquired texel image information, processing for determining the amount and direction of movement of the vertices and calculating the position coordinates of the vertices after movement by vector operation (matrix operation) is performed for a given vertex shader program ( In a broad sense, it is executed according to the first shader program. Note that the texel image information does not necessarily have to be changed (updated) over time. For example, by individually providing the time parameter to the vertex shader unit 122, the amount of movement and the direction of movement of the vertex can be determined based on the acquired image information and the time parameter. The vertex movement information obtained from the image information may be at least one of the vertex movement amount or the vertex movement direction.

  More specifically, a height map texture in which texel image information is changed according to height information (displacement from a given reference plane), and texel image information in normal vector information (normal vector direction) The normal map texture that is changed according to These textures are stored in the texture storage unit 175 (height map data storage unit, normal map data storage unit) of the storage unit 170.

  In addition, the vertex shader unit 122 determines that the contact event occurrence flag is set when the event determination unit 114 determines that a contact event occurs in which another object (character, car, or the like) contacts the deposit model object. If it is set to on, vertex shading is performed in which a given vertex shader program is executed to move the vertices constituting the deposit model object in the direction opposite to the deposition direction. In other words, vertex shading is performed so that the volume occupied by the object of the sediment model decreases along the shape of another object that contacts the object of the sediment model.

  Further, the vertex shader unit 122 restricts (prohibits) the movement of the vertex in the accumulation limitation area when the accumulation limitation area is set for the original object of the deposit model by the accumulation limitation area setting unit 116. Perform vertex shading.

  The vertex shader unit 122 also turns on the sediment movement event occurrence flag when it is determined that a sediment movement event in which the sediment moves such as an event where snow falls from a high place or an avalanche event has occurred. The sediment model object placed in the first area is moved in the direction opposite to the deposition direction, and the deposit model object placed in the second area is moved. Vertex shading is performed to move the vertices in the stacking direction. In this way, it is possible to simply express how the deposit moves. Note that a state in which the deposit moves from the first area to the second area by animation processing during the vertex shading performed in the first area and the second area may be expressed.

  When the vertex shading for moving the vertex of the original model object of the deposit is performed, the pixel shader unit 124 stores image information (color, luminance, α value, etc.) on the model object of the deposit after the vertex shading. ) Change pixel shading. For example, after the deposition event ends, pixel shading can be performed in which image information is changed in pixel units for a model object of a deposit whose vertex is moved in a direction opposite to the deposition direction. Specifically, vector data whose direction is randomly changed is given to the pixel of the part where the snow is melted in the model object, and the inner product of the vector and the line-of-sight vector of the virtual camera is obtained. By controlling the reflectivity accordingly, it is possible to express how the accumulated snow melts and shines.

  Further, the pixel shader unit 124 performs processing for reading out the texture (texel value) stored in the texture storage unit 175 and mapping it to the model object. Specifically, the texture (surface properties such as color and α value) is read from the texture storage unit 175 using the texture coordinates set (given) to the vertices of the model object. Then, a texture that is a two-dimensional image or pattern is mapped to a model object. In this case, processing for associating pixels and texels, bilinear interpolation (texel interpolation), and the like are performed.

  Here, the vertex shader unit 122 and the pixel shader unit 124 described above are a kind of so-called programmable shader that can program polygon (primitive) drawing processing by a shader program described in a shading language. Programmable shaders can be programmed with vertex-based processing and pixel-by-pixel processing, so the degree of freedom of polygon drawing processing is high, and the expressive power is greatly improved compared to fixed processing in conventional hardware. be able to.

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

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

2. 2.1 Method of Present Embodiment 2.1 Deposition Event Representation Method In this embodiment, the vertex shading is performed to move the vertex of the original object of the snow surface model placed and set on the terrain object, in the state of snow falling on the ground surface. It expresses by. Of course, the present invention is not limited to expressing an event in which snow falls on the ground surface, but expresses a state in which deposits such as snow, ash, dead leaves or sand accumulate on various objects arranged and set in the object space. Can be applied when.

  For example, when a height map texture is used, vertex shading for expressing a deposition event can be performed as follows.

  First, a height map texture (height map data in a broad sense) in which height information is set for texels (grid points) arranged in a grid pattern is associated with the original object of the deposit model.

  Next, the height information set in the texel (grid point) is acquired with reference to the height map texture associated with the original object of the deposit model. The height information set in each texel of the height map texture is set as a function having time as a parameter, and the value changes according to the elapsed time from the occurrence of the deposition event. In addition, information for determining the moving direction of the vertex is also acquired. The information for determining the movement direction is a parameter that gives permission to move in the X axis direction, the Y axis direction, and the Z axis direction of the world coordinate system.

  Next, based on the vertex movement information including the acquired height information and information for determining the movement direction, the position coordinates after the movement of the vertex are calculated. Finally, the vertex of the original model object of the deposit is moved to the obtained position coordinates, and vertex shading is performed in which the vertex moves in the deposition direction with time. Information for determining the moving direction of the vertex may be given as normal vector information set in a texel of a normal map texture described later.

  This will be described more specifically with reference to FIGS. 2 (A) to 2 (E). FIG. 2A shows a height map texture. In the height map texture, height information h (t) that changes according to time t is set in the texel TXL. The height information h (t) is a function value having the elapsed time t after the occurrence of the deposition event as a parameter, and the height information h at the elapsed time t is obtained by multiplying or adding the time parameter to the deposition rate parameter. (T) can be obtained. Different deposition rate parameters may be set for each texel. In the method of this embodiment, the amount of movement of the vertex of the original object of the snow surface model is determined based on the height information h (t). In this example, at a time t by matrix calculation (vector calculation) by a vertex movement matrix (vertex movement vector) that displaces the vertex in the positive direction (upward direction; in a broad sense, the accumulation direction) of the Y axis of the world coordinate system. Find the vertex coordinates.

  In FIG. 2B, a snow accumulation event occurs, and the snow surface model original object MOB is placed on the terrain object GOB representing the ground. The height information h (t) set in the texel of the height map texture changes with the passage of time t, and each vertex of the original object MOB of the snow surface model is associated with the texel of the height map texture. When the resolution of the height map texture (texel resolution) is lower than the resolution (vertex resolution) of the original object MOB of the snow surface model, height information corresponding to the vertex can be obtained by linear interpolation. Assuming that the time t1 has elapsed since the correspondence between the vertex and the texel has been completed and the deposition event has started, the vertex movement matrix (in which the position coordinate of the vertex is displaced by the movement amount h (t1) in the positive direction of the Y axis ( Using the vertex movement vector, position coordinates (X, Y + h (t1), Z) after movement of the vertex P (position coordinates (X, Y, Z)) of the original object are obtained. That is, as shown in FIG. 2C, each vertex of the original object of the snow surface model is moved by h (t1) in the positive direction (upward direction) of the Y axis. This kind of vertex shading eliminates the need to prepare a large amount of model data, which not only saves memory usage but also reduces the amount of data that changes the height of the snow surface over time. Can be expressed realistically.

  When the accumulation event ends, the snow surface model object MOB ′ whose vertex has moved in the accumulation direction, in other words, the direction in which the volume increases, has its vertex in the direction opposite to the accumulation direction, in other words, the volume decreases. You may perform vertex shading which moves a vertex to a direction. That is, when the deposition event occurrence flag is reset, that is, when the flag is set from the on state to the off state, it is determined that the deposition event has ended, and the volume of the deposit model increases with time. Vertex movement processing is performed in which the vertexes constituting the object of the deposit model that has been moved are moved in a direction in which the volume of the deposit model decreases. In this way, for example, after the accumulation event in which snow is accumulated, it is possible to express how the accumulated snow gradually melts.

  Specifically, in the height map texture, height information h ′ (t) that determines the amount of movement of the apex in the negative direction of the Y axis (downward; in a broad sense, the direction opposite to the deposition direction) is set in the texel. Keep it. That is, the height information h ′ (t) is given as a function value that changes with the time t as a parameter. Then, the height information h ′ (t) is referred to the height map texture set in the texel, and the texel is associated with the vertex of the object MOB ′ of the snow surface model. When the association between the vertex and the texel is completed, the vertex is moved in the negative direction of the Y axis as shown in FIG. Similarly, the displacement of the position coordinates is performed using the vertex movement matrix (vertex movement vector). If the time t2 has elapsed since the deposition event ended, as shown in FIG. 2 (E), P (X, The position coordinates are converted so that the vertex is moved from Y + h (t1), Z) to P2 (X, Y + h (t1) −h ′ (t2), Z). In this way, it is possible to realistically express how snow that has accumulated has melted.

  It should be noted that during the occurrence of a deposition event as shown in FIGS. 2B and 2C, vertex movement information (first vertex in a broad sense) in which the amount of movement in the deposition direction increases with time. 2D and FIG. 2E, the vertex of the original object MOB of the deposit model is moved in the positive direction of the Y axis (upward direction; in a broad sense, the accumulation direction) based on the movement information). After completion of such a deposition event, apex movement information (in a broad sense, the amount of movement in the negative direction of the Y axis (downward; in the broad sense, the direction opposite to the deposition direction) increases with time. Based on the second vertex movement information), the vertex of the deposit model object whose vertex is moved in the deposition direction is moved in the negative direction of the Y axis (downward; in the broad sense, the direction opposite to the deposition direction). You may make it make it. In this way, it is possible to express how the snow is falling and increasing in height while the accumulation event occurs, and how the snow is gradually melting after the accumulation event is completed.

  In addition, the expression of the deposition event according to the present embodiment can be realized using a normal map texture. When using a normal map texture, vertex shading for expressing a deposition event can be performed as follows.

  Even in this case, first, a normal map texture (normal map data in a broad sense) in which normal vector information (direction of the normal vector) is set to the texel (grid point) for the original object of the sediment model. ). Next, the normal vector information set in the texel (grid point) is acquired with reference to the normal map texture associated with the original object of the deposit model. In addition, information for determining the amount of movement of the vertex that changes according to the elapsed time after the occurrence of the deposition event is also acquired. Then, based on the vertex movement information including the direction of the obtained normal vector and the amount of movement of the vertex, the position coordinates of the vertex obtained by moving the vertex of the original object of the sediment model along the direction of the normal vector are obtained. calculate. That is, in this method, the moving direction of the vertex is given by the direction of the normal vector.

  Note that the information for determining the amount of movement of the vertex may be given by the height information set in the texel of the height map texture described above. As information for determining the amount of movement of the vertex, a sine component or cosine component of a normal vector set in a texel of the normal map texture may be used.

  A method of moving the vertices of the original object of the snow surface model using the normal map texture will be described with reference to FIGS. 3 (A) to 3 (C). As shown in FIG. 3A, the normal map texture is a texture in which normal vector information, which is the orientation of the surface of a primitive (polygon) that constitutes an object, is set in a texel. In this method, the direction of the vector (angle around the X axis, angle around the Y axis, angle around the Z axis) given by the normal vector set in the texel of the normal map texture is the vertex movement direction. The amount of movement of the vertex can be obtained by multiplying or adding a normal vector, which is a normalization vector, with a deposition rate parameter d (t) whose value changes with time. The deposition rate parameter d (t) is a function value having the time t as a parameter, and can be individually set for each vertex as a parameter associated with the vertex. For example, since it is difficult for snow to accumulate in the sunny part, the deposition rate parameter d (t) is set so that the amount of movement of the vertex is small. On the other hand, since snow is likely to accumulate in the shaded part, the amount of movement of the vertex is large. The deposition rate parameter d (t) can be set so that The deposition rate parameter d (t) can also be set as a parameter common to each vertex.

  When a snow event occurs in the object space as shown in FIG. 3B, first, the normal map texture is referred to associate the texel with the vertex. Next, with the direction of the normal vector set in the texel associated with each vertex as the vertex moving direction, the vertex based on the normal vector NV and the deposition rate parameter d (t1) set for each vertex Using the movement vector Vd (vertex movement matrix), the position coordinates after the movement of the vertex P are obtained, and the vertex is converted from the coordinates (X, Y, Z) to the coordinates (X * Vdx, Y) as shown in FIG. * Vdy, Z * Vdz). Vdx, Vdy, and Vdz correspond to the X-axis component, the Y-axis component, and the Z-axis component of the vertex movement vector Vd. Even in this case, as in the case of using the height map texture, it is possible to realistically represent the state of snow falling. In addition, it is possible to use a normal map texture to express how snow melts. For example, the deposition rate parameter d ′ (t) is set (defined) with a function value that obtains a negative value, or the normal vector of the model object on the snow surface is inverted, and the direction of the inverted vector is determined. You may obtain | require a vertex movement vector (vertex movement matrix) so that it may become the moving direction of a vertex. For example, the deposition rate parameter d ′ (t) is set so that the amount of movement of the apex is large because the snow is easily melted in the sunny portion, while the snow is covered in the shaded portion. Since it is difficult to solve, the deposition rate parameter d ′ (t) can be set so that the amount of movement of the apex is small.

  In the present embodiment, as shown in FIG. 4A, a hit check area HC (bounding volume, bounding box) is set in the original object MOB of the snow surface model, and contact with other objects is performed. The hit check process to detect is performed. When the accumulation event occurs, the vertex group constituting the original object MOB of the snow surface model is moved, or when the accumulation event ends, the vertex group of the object MOB ′ of the snow surface model is moved in the direction opposite to the accumulation direction. When moved, as shown in FIG. 4B, the hit check area HC ′ is reset (updated) based on the position coordinates of the vertices constituting the moved object. As a result, it is possible to perform hit check processing that reflects the effects of rising and falling of the snow surface.

  Here, the hit check area is set based on an area occupied by a simple object having a simple shape such as a cube or a sphere formed so as to include the vertex of the object to be set. Specifically, the maximum value and the minimum value for all coordinate components (X coordinate component, Y coordinate component, and Z coordinate component) of the vertex of the object are detected, and a plane passing through the vertex that takes the maximum value and the minimum value is included. By setting the arrangement of the simple object, the hit check area can be set as the area occupied by the simple object in the object space.

  Here, as shown in FIGS. 4A and 4B, the hit check area HC may be set to one hit check area for the entire snow surface model. If there is an area where the rising and falling rates of the snow surface are different, there is a case where appropriate hit check processing cannot be performed.

  Therefore, as shown in FIG. 5A, a plurality of hit check areas HC1 to HC2 are set for the original object MOB of the snow surface model, and the hit check areas HC1 ′ to HC3 ′ are set for each hit check area. May be reset (updated). In this way, it is possible to set an appropriate hit check area even when there are areas where the vertex movement amount is large and areas where the vertex movement amount is small.

  In the present embodiment, it is possible to express a state where accumulated snow can be accumulated by locally increasing the amount of movement of the vertex in a given area of the original object of the snow surface model. Specifically, when the height map texture is used, the height information h (t) is set to be locally increased in texels belonging to a given area. Also, when using a normal map texture, the deposition rate parameter d (t) is set to be large for vertices belonging to a given area.

  By the way, when an object that becomes a heat source is placed on the snow surface, for example, near the exhaust port of a car, near the engine of a motorcycle, or around a bonfire, etc., it is difficult for snow to accumulate, or The phenomenon that snow does not pile up occurs. In order to express such a phenomenon, in the present embodiment, the accumulation restriction area may be set for the original object of the snow surface model by preparing a texture for setting the accumulation restriction area.

  Specifically, it is possible to acquire a deposition restriction parameter set in the texel with reference to the deposition restriction texture, and adjust the vertex movement amount based on the deposition restriction parameter. The deposition limitation parameter set in the texel of the deposition limitation texture is a parameter that is multiplied by a parameter that determines the amount of movement of the vertex, and can take a value between 0 and 1, for example. In this case, as shown in FIG. 6, by setting the deposition limit parameter to 1 in the non-deposition limited area and to a value smaller than 1 (for example, 0.5) in the deposition limited area. The amount of vertex movement can be limited. When the deposition limit parameter is set to 0, the vertex movement amount can be set to 0. That is, the movement of the vertex can be locally restricted (prohibited).

  In the expression method of this embodiment, in addition to vertex shading that moves vertices according to the passage of time, pixel shading that changes image information that determines the drawing color of the deposit model according to changes in time or the amount of deposition. May be performed. That is, a flag is set that the texture of the deposit has changed according to the change in time or the amount of deposit. In the pixel shader, the flag is discriminated and the image information (color, luminance, refractive index, reflectance, α value, etc.) of the pixel displaying the deposition model is changed (adjusted) by switching the image to be texture mapped. For example, when the accumulated snow is thawed, pixels corresponding to the thawed portion of the snow surface model can be drawn with a sparkling color. In this case, it is possible to determine whether snow has accumulated or has been solved according to the polarity of the vertex movement rate (deposition rate) of the snow surface model. For example, as shown in FIGS. 2B and 2C, when the apex moves in the positive direction (upward direction; accumulation direction in a broad sense) of the Y axis, it is determined that snow is piled up. If the apex moves in the negative direction of the Y axis (downward; in the broad sense, the direction opposite to the accumulation direction), it can be determined that the snow has melted. If it is determined that the snow has melted, the image information (reflectance) is changed (adjusted) so that the gloss becomes stronger. More specifically, a normal map texture in which the direction of the normal vector is scattered by adding random noise is prepared, and the reflectance of pixels with a normal vector that matches the direction of the light source vector or the line-of-sight vector is set. Can be performed (pixel shading). In other words, the pixel having a high reflectance can be made more glossy by being drawn with a color having a high luminance.

2.2 Method for expressing a contact event In this embodiment, when another object contacts or collides with an object whose vertex has been moved in the deposition direction due to the occurrence of a deposition event, the vertex is displayed in a direction opposite to the deposition direction. Adopt a moving vertex shading technique.

  Specifically, a height map texture (height map data in a broad sense) is associated with other objects as in the deposit model. The height information set in the texels (grid points) of the height map texture associated with other objects does not have to represent the shape of the surface formed by the vertices that make up the other object, It may be set (defined) virtually as a surface shape of another object. For example, for a car tire, a tire-like image is represented by texture mapping an image representing the tire groove on a disk-shaped object that does not have a tire groove, and height information representing the actual groove irregularities is separately provided for the tire. It can be defined (set) with a height map texture associated with the object.

  As shown in FIG. 7A, when a contact event (collision event) occurs in which the ball object (other object) BOB contacts (collises) with the object MOB of the snow surface model, it corresponds to the ball object. With reference to the attached height map texture, the height information set in the texel (grid point) corresponding to the vertex constituting the contact area of the ball object BOB is acquired. The generation of the contact event is performed by hit check. As shown in FIG. 7A, the hit event is generated in the hit check area HC1 (first hit check area) and the ball object BOB set for the object MOB of the snow surface model. On the other hand, when the hit check area HC2 (second hit check area) set for the area overlaps, it is determined that a contact event has occurred, and the contact event occurrence flag is set to ON.

  When the snow surface model is deformed, a new vertex is generated in the contact area of the snow surface model and the polygon is subdivided as shown in FIG. 7B. That is, when a contact event occurs and the vertex group corresponding to the contact area of the deposit model object is moved in the direction opposite to the deposition direction, the vertex generation process is performed to the deposit model object. A new vertex may be generated. In other words, when a contact event occurs, the polygons constituting the deposit model object may be subdivided. Thereby, even if the resolution of the original object of the deposit model is lowered, the contact trace (collision trace) can be expressed in detail.

  Finally, as shown in FIG. 7C, based on the acquired texel value (grid point height information), the vertex group corresponding to the contact area of the object MOB of the snow surface model is represented on the Y axis. A process of moving in the negative direction (downward; in a broad sense, the direction opposite to the deposition direction) is performed. That is, the vertex group is moved in a direction to reduce the volume occupied by the object MOB of the snow surface model. At this time, in the vertex group movement process, the height information obtained from the height map texture is a parameter for determining the vertex movement amount. Further, the movement direction may be given by a parameter instructing movement in a given axial direction (X-axis direction, Y-axis direction, and Z-axis direction) as in this example, or a primitive surface of another object BOB. The direction of the normal vector representing the direction of the vertex may be used as the moving direction of the vertex. When the vertex of the snow surface model object MOB is moved due to the occurrence of the contact event, it is desirable to reset the hit check area HC1 based on the position of the vertex after the movement.

  When a contact event occurs, the level of detail (resolution, resolution) of the deposit model object may be changed according to the distance between the contact position between the deposit model object and another object and the virtual camera. Further, the content of vertex shading may be changed according to the distance between the contact position and the virtual camera.

  For example, as shown in FIG. 8, when the contact position is within the first distance range R1 from the virtual camera VC, vertex shading is performed to move the vertex group corresponding to the contact position of the object of the deposit model, When the contact position is within the second distance range R2 farther than the first distance range R1 from the virtual camera VC, normal mapping or bump mapping is performed on the contact position of the object of the deposit model. The trace of the object can be represented. In addition, when a contact event occurs in the third distance range R3 that is further from the virtual camera VC than the second distance range R2, texture mapping is performed on the contact area of the deposit model object. Thus, it is possible to easily express the contact trace of another object.

  Also, when a contact event occurs, the height set in the texel according to the movement information of other objects, the type of deposit (material information), or the load applied to the deposit model object. A process may be performed in which a plurality of height map textures that differ in at least one of the information and the range of the contact area are switched to move a vertex group constituting the contact area of the object of the deposit model.

2.3 Method for Representing Sediment Movement Event Next, a method for representing the event that the sediment moves will be described. This technique can be applied, for example, to express a sediment fall event or an avalanche event.

  In the present embodiment, when an event in which a deposit such as snow or ash moves in the object space occurs, the vertex of the deposit model object is set in the negative direction of the Y axis (first area). Move downward (in the broad sense, the direction opposite to the deposition direction), and at the destination (second area), move the vertex of the deposit model object in the positive direction of the Y axis (upward; broadly, A method of moving in the deposition direction) is adopted. This makes it possible to generate an image that makes it appear as if the deposit has moved from the source to the destination.

  The vertex group at the movement source and the vertex group at the movement destination may constitute one model object, or may constitute separate model objects. Further, the state of moving from the movement source area to the movement destination area may be interpolated by animation processing using a texture. In this way, the vertex movement process need only be performed in the area of the movement source and the area of the movement destination, so that the calculation load can be reduced without degrading the quality of the video.

  This technique can also be applied to the case where a sediment movement event occurs during the occurrence of a deposition event. For example, if a deposit is deposited to a given height during a deposition event, in other words, if the vertex of the deposit model object has moved to a given set coordinate, a fall event or avalanche event can be generated. That is, when a given condition is satisfied during the deposition event, the sediment movement event occurrence flag is set to ON.

  For example, when an event that snow falls on a tree branch occurs, when the amount of snow that has accumulated on the branch reaches a predetermined amount, the object of the snow surface model that is placed and set on the branch The vertex group corresponding to the fall area of the object of the snow surface model set to be placed on the terrain model without being displayed may be moved in the accumulation direction. In this case, the movement amount of the vertex group of the object of the snow surface model corresponding to the fall area can be moved according to the amount of snow falling from the top of the branch.

  Further, for example, when an avalanche event occurs, as shown in FIG. 9, vertex groups are formed at the upper part (movement source: first area) and lower part (movement destination: second area) of the slope where the snow slides due to the avalanche. It can be expressed by linking movements of That is, at the upper part of the slope, the apex is suddenly moved in the direction opposite to the deposition direction (downward, negative Y-axis direction), and at the lower part of the slope, the deposition direction (upward, positive Y-axis direction) is suddenly moved. ) To move the vertex. In a frame between the movement of the apex at the upper part of the slope and the movement of the apex at the lower part of the slope, an animation during the avalanche may be generated by performing an animation process with a texture expressing the avalanche. For example, while snow is moving, the avalanche and the state of falling can be connected to a plate-shaped polygon (sprite) by texture mapping the avalanche expression texture and the fall expression texture to perform animation processing. Even when the deposit movement event occurs and the vertex group of the deposit model is moved, it is desirable to reset the hit check area based on the position coordinates of the vertex after the movement.

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

  As shown in FIG. 10, it is first determined whether or not it is a frame update (1/60 second) timing (step S10). If it is the frame update timing (YES in step S10), it is determined whether or not a deposition event has occurred (step S11). If it is determined that a deposition event has occurred (YES in step S11), a deposition event occurrence flag is set to on (step S12). If it is determined that no deposition event has occurred, the process proceeds to step S13 and subsequent steps without going through step S12.

  Next, the shader program for the vertex shader and the pixel shader is transferred, and various parameters necessary for performing the rendering process by executing the shader program are set (steps S13, S14, S15). Then, the vertex list of the deposit model is transferred to the vertex shader (step S16), and the vertex shader program and the pixel shader program transferred in steps S13 and S14 are sequentially executed (steps S17 and S18).

  The vertex shader performs vertex shading according to the flowchart shown in FIG. First, the accumulation event occurrence flag is confirmed (step S20). If the accumulation event occurrence flag is ON (YES in step S20), FIG. 2 (A) to FIG. 2 (C) or FIG. 3 (A) to FIG. As described in 3 (C), the amount of movement of each vertex in the direction of each axis of the X axis, Y axis, and Z axis is determined (step S21). For example, when using a height map texture, the amount of movement of the vertex in the Y-axis direction is determined based on the height information set in the texel. Next, it is confirmed whether or not each vertex belongs to the accumulation prohibited area where the movement of the vertex is prohibited (step S22). For vertices belonging to the accumulation prohibited area (YES in step S22), the vertex movement amount is set to 0 (step S23). Note that the amount of movement of the vertex belonging to the accumulation prohibited area may be set to 0 by multiplying the amount of movement obtained in step S21 by the accumulation limit parameter. As for the vertices that do not belong to the accumulation prohibited area, as described in FIG. 2C or FIG. 3C, the vertices are moved according to the movement amounts in the respective axial directions obtained in step S21 (step S24). In other words, processing for converting the position coordinates of the vertex is performed by matrix calculation (vector calculation). Next, coordinate system conversion processing is performed by geometry processing such as perspective conversion, and the screen coordinates of the vertices of the deposit model are calculated (step S25). At this time, texture coordinates are set. Finally, the created vertex data is transferred to the pixel shader and the vertex shader program is terminated.

  Next, the pixel shader executes the pixel shader program according to the flowchart of FIG. First, when the vertex shading is completed, the moving direction and moving amount of each vertex are calculated based on the vertex data transferred from the vertex shader (step S30). That is, displacement data between the position coordinates of the vertex of the original object and the position coordinates after the vertex shading is obtained. Next, the color of each pixel is set based on the obtained moving direction and moving amount of the vertex (step S31). Specifically, texture mapping, α blending, etc. are performed to set the pixel color of the deposit model. decide. For example, if it is determined that the vertex is moving downward, the color of the pixel is determined so as to increase the gloss according to the amount of movement. Then, the determined color data is output to the frame buffer, and the pixel of the deposit model is drawn (step S32).

4). Hardware Configuration FIG. 13 shows an example of a hardware configuration that can realize this embodiment. The main processor 900 operates based on a program stored in a DVD 982 (information storage medium, which may be a CD), a program downloaded via the communication interface 990, a program stored in the ROM 950, or the like. Perform processing, sound processing, etc. The coprocessor 902 assists the processing of the main processor 900, and executes matrix operation (vector operation) at high speed. For example, when a matrix calculation process is required for a physical simulation for moving or moving an object, a program operating on the main processor 900 instructs (requests) the process to the coprocessor 902.

  The geometry processor 904 performs geometry processing such as coordinate conversion, perspective conversion, light source calculation, and curved surface generation based on an instruction from a program operating on the main processor 900, and executes matrix calculation at high speed. The data decompression processor 906 performs decoding processing of the 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 (vertex data and other parameters) to the drawing processor 910 and, if necessary, the texture to the texture storage unit 924. Forward. 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. Programmable shaders such as a vertex shader and a pixel shader are also mounted on the drawing processor 910. According to the shader program that realizes the method of this embodiment, the creation / change (update) of vertex data and the drawing color of pixels (or fragments) are changed. Make a decision. When an image for one frame is written in the frame buffer 922, the image is displayed on the display 912.

  The sound processor 930 includes a multi-channel ADPCM sound source and the like, 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, in the description or drawings, terms that are broad or synonymous (Y-axis positive direction (upward), Y-axis negative direction (downward), virtual camera, pixel, height map texture, normal map texture, etc. ) (Deposition direction, direction opposite to the deposition direction, viewpoint, fragment, height map data, normal map data, etc.) are terms that are broadly or synonymous in the description or other descriptions in the drawings. Can be replaced. Further, the method for expressing the deposition event, the method for expressing the contact event, or the method for expressing the deposit movement event are not limited to those described in the present embodiment, and methods equivalent to these methods are also included in the scope of the present invention.

  In the present embodiment, the case where the original object of the sediment model (for example, the snow surface model) is arranged on the terrain object has been described as an example. However, the present invention is not limited to this, and the terrain object itself Can also be used as the original object of the sediment model.

  The present invention can also be applied to various games (such as fighting games, shooting games, robot fighting games, sports games, competitive games, role playing games, music playing games, dance games, etc.). Further, the present invention is applied to various image generation systems such as a business game system, a home game system, a large attraction system in which a large number of players participate, a simulator, a multimedia terminal, a system board for generating a game image, and a mobile phone. it can.

It is a functional block diagram of this embodiment. 2A to 2E are explanatory diagrams of the vertex shading technique in the deposition event of the present embodiment. FIG. 3A to FIG. 3C are explanatory diagrams of the vertex shading method in the deposition event of the present embodiment. 4A and 4B are explanatory diagrams of a hit check area setting method according to the present embodiment. FIG. 5A and FIG. 5B are explanatory diagrams of a hit check area setting method according to this embodiment. It is explanatory drawing of the setting method of the accumulation | storage limitation area of this embodiment. FIG. 7A to FIG. 7C are explanatory diagrams of the vertex shading technique in the contact event of this embodiment. It is explanatory drawing of the switching method of the detail level according to the distance from the virtual camera of this embodiment. It is explanatory drawing of the vertex shading method in the sediment movement event of this embodiment. It is a flowchart which shows the specific process example of this embodiment. It is a flowchart which shows the specific process example of this embodiment. It is a flowchart which shows the specific process example of this embodiment. It is an example of a hardware configuration.

Explanation of symbols

GOB terrain object,
Original object of MOB sediment model,
MOB ', MOB 煤 @Sediment model object after vertex shading,
HC, HC1-HC3 hit check area
100 processing unit,
111 object space setting unit, 112 movement / motion processing unit,
113 virtual camera control unit, 114 event determination unit,
115 hit check area setting section, 116 accumulation limit area setting section,
120 image generation units, 122 vertex shader units, 124 pixel shader units,
130 sound generation unit, 160 operation unit,
170 storage unit,
171 main storage unit, 173 frame buffer, 175 texture storage unit,
180 information storage medium, 190 display unit, 192 sound output unit,
194 Portable information storage device, 196 communication unit

Claims (13)

A program for generating an image,
An event determination unit that determines whether or not a deposition event in which the amount of deposit increases in the object space has occurred;
When it is determined that the accumulation event has occurred, vertex shading is performed to change the vertex data of the original object of the sediment model, and the object space is viewed from a given viewpoint based on the vertex data after the vertex shading. As an image generator that generates
Make the computer work,
Normal map data in which normal vector information is set in a grid pattern is associated with the original object of the deposit model,
The image generator
The normal vector information set to the grid points is acquired with reference to the normal map data associated with the original object of the deposit model, and includes the acquired normal vector information and varies with time. A program for performing vertex shading for moving a vertex of an original object of the deposit model along a direction of a normal vector based on vertex movement information. In claim 1,
Height map data in which height information is set in a grid pattern is associated with the original object of the deposit model,
The image generator
Reference is made to height map data associated with the original object of the deposit model to obtain height information set at grid points, and based on the vertex movement information including the obtained height information, the deposit A program that performs vertex shading that moves the vertices of an original object of an object model along the direction of a normal vector . In claim 1 or 2 ,
The event determination unit
A determination is made as to whether or not a contact event has occurred in which another object contacts the object of the deposit model whose vertex has been moved along the direction of the normal vector ;
Height map data in which height information is set in a grid pattern is associated with the other object,
The image generator
Above with reference to height map data associated with the other objects acquired height information set in the lattice points, based on the obtained height information which, normals to the vertices of the object of the deposit model A program that performs vertex shading that moves in the direction opposite to the vector direction . In claim 3 ,
The event determination unit
Determining that the contact event has occurred when a first hit check area set for an object of the deposit model and a second hit check area set for the other object overlap;
Vertices said normal vector of the object in the original case the object vertices of is moved along the direction of the normal vector the deposit model or the vertex is moved along the direction of the normal vector, of the deposit model If the orientation has been moved in the opposite direction, based on the positions of the vertices after movement, the hit check area set to reconfigure the first hit check area set for the object of the deposit model A program that causes a computer to function as a section. In any one of Claims 1-4 ,
Causing the computer to function as a deposition limit area setting unit that sets a deposition limit area on the original object of the deposit model;
The image generator
A program for performing vertex shading for restricting movement of vertices in the accumulation restriction area when the accumulation restriction area is set for an original object of the deposit model. In any one of Claims 1-5 ,
The image generator
When vertex shading for moving the vertex of the original object of the deposit model is performed, pixel shading for changing image information in units of pixels is performed on the object of the deposit model after the vertex shading. . In any one of Claims 1-6 ,
The image generator
A program for performing vertex shading for moving a vertex of an object of a sediment model in a direction opposite to a direction of the normal vector when the deposition event is completed. In claim 7 ,
The image generator
During the occurrence of the deposition event, based on the first vertex movement information, move the vertex of the original object of the deposit model along the direction of the normal vector ,
After the deposition event ends, the vertex of the object of the deposit model in which the vertex is moved along the direction of the normal vector based on the second vertex movement information different from the first vertex movement information is the normal vector. A program characterized by performing vertex shading that moves in the direction opposite to the direction of. In claim 7 or 8 ,
The image generator
A program characterized by performing pixel shading for changing image information in units of pixels for an original object of a deposit model whose vertex has been moved in a direction opposite to the direction of the normal vector after the deposition event ends. In any of the claims 1-9,
The event determination unit
Determining whether a deposit movement event has occurred in which the deposit moves from the first area to the second area in the object space;
The image generator
When it is determined that the sediment movement event has occurred, the vertex of the object of the sediment model is moved in the direction opposite to the direction of the normal vector in the first area, and the second area In this area, the program performs vertex shading that moves the vertex of the object of the sediment model along the direction of the normal vector . In any one of Claims 1-10 ,
Vertex movement information different from other areas is set in a given area of the original object of the deposit model,
The image generator
A program for performing vertex shading for moving a vertex of an original object of the deposit model along a direction of a normal vector based on vertex movement information set for each area. An information storage medium readable by a computer, wherein the program according to any one of claims 1 to 11 is stored. An image generation system for generating an image,
An event determination unit that determines whether or not a deposition event in which the amount of deposit increases in the object space has occurred;
When it is determined that the accumulation event has occurred, vertex shading is performed to change the vertex data of the original object of the deposit model, and the object space is determined from a given viewpoint based on the vertex data after the vertex shading. An image generator for generating the viewed image;
Including
Normal map data in which normal vector information is set in a grid pattern is associated with the original object of the deposit model,
The image generator
The normal vector information set to the grid points is acquired with reference to the normal map data associated with the original object of the deposit model, and includes the acquired normal vector information and varies with time. An image generation system characterized by performing vertex shading that moves a vertex of an original object of the deposit model along a direction of a normal vector based on vertex movement information.

Images