JP2003091740A - Image forming system, program and information storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming system, a program, and an information storage medium capable of processing the formation of an image for reflecting a field obtained by a simulation operation in real time. SOLUTION: The field of changing the size or the dividing number of a flow field of 1 or influence of the field is set in an object space. When arranging an object WOBJX in the flow field or a position for reflecting influence of the flow field, a position of a constitution point of the object WOBJX and information (color information, and transparency information) related to the constitution point changes on the basis of information on respective lattice points of the flow field. When the positions of the constitution point of the object are respectively changed on the basis of flow field information (for example, a speed vector) on the respective lattice points of the flow fields HFX1 to HFX3 different in size or dividing number, the object WOBJ is deformed as objects OBJX1 to OBJX3. The size of the flow fields may be changed according to an occurrence state of an event and a processing load.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, it has been possible to artificially represent natural phenomena such as movement of water by using techniques such as texture animation. However, the expression became monotonous and could not be expressed in a more realistic manner.

As a realistic representation of such a natural phenomenon, a flow field is obtained by fluid simulation,
There is a method to reflect this flow field in the operation of the object.

However, the conventional fluid simulation has a heavy processing load, and since the purpose is to visualize the operation of the flow field in the end, real-time processing has not been performed. Therefore, it is not possible to reflect the influence of the flow field obtained by the fluid simulation on the object image based on the external factors that occur interactively.

The present invention has been made in view of the above problems, and an object of the present invention is to generate an image capable of processing in real time the generation of an image reflecting a field obtained by a simulation operation. To provide a system, a program, and an information storage medium.

[0006]

In order to solve the above-mentioned problems, the present invention relates to an image generation system for generating an image, which is formed on the basis of a physical quantity at each point obtained by dividing a simulation space. , A size, the number of divisions, a setting position, a setting number, and a field setting means for changing and setting at least one of the shapes; A means for changing the position of the primitive or information associated with the primitive by using the physical quantity at each point of, and means for generating an image viewed from a given viewpoint in the object space in which the primitive is arranged. Is characterized by. A program according to the present invention causes a computer to function as the above means. An information storage medium according to the present invention is a computer-readable information storage medium,
A program that causes a computer to function as the above means is stored.

Here, the object space means a virtual three-dimensional space in which objects (primitives) whose shapes are specified by, for example, definition points (vertex of polygons or control points of free-form surface) are arranged.

The field means a region where physical quantities are spatially distributed.

It should be noted that not only the physical quantity of the field obtained by the simulation calculation but also the information that changes based on the information of the flow field of the field (for applying to the object, based on the information of the flow field of the above physical quantity) Result of calculation)
The present invention can also include the case where the position of the primitive is changed by using.

Further, the information associated with the primitive means color (luminance) information, transparency information and the like given to each primitive.

According to the present invention, at least one of the field size, the number of divisions, the set position, the set number, and the shape is changed, and the position of the primitive or the primitive is changed based on the field information obtained by the simulation calculation. Since the information associated with is changed to generate the image in the object space, the processing load of the simulation can be made variable. Therefore, if realism is required, the processing load of the simulation is sacrificed by making the number of divisions smaller, and if realism is not needed, the number of divisions is made coarser. The processing load can be reduced.

Thus, in consideration of the balance between the processing load of the simulation calculation and the generation of a realistic image in which the position and the state are changed based on the simulation calculation,
The image generation process can be optimized.

Further, the image generating system, the program and the information storage medium according to the present invention include means for changing the position of the particle or the information associated with the particle by using the physical quantity at each point of the field. To do.

Here, the information associated with the particles means, for example, the life, size, color information and transparency information of the particles.

According to the present invention, the position and the state of the particles are changed by using the field information obtained by the simulation calculation in the simulation space. Therefore, the influence of external factors interactively generated in the object space can be reduced. It becomes possible to generate a realistic image representing the reflected natural phenomenon.

The image generation system, the program and the information storage medium according to the present invention include means for monitoring the processing load (store a program that causes a computer to function as the means or causes the computer to function). The field setting means changes and sets at least one of the size, the number of divisions, the set position, the set number, and the shape of the field according to the processing load.

In the present invention, for example, when it is determined that the processing load is high, the size of the field is reduced or the number of divisions is set roughly so that the realism of the expression is sacrificed to some extent. Can be reduced.
On the other hand, when it is determined that the processing load is low, the size of the field is increased or the number of divisions is set finely to further improve the position of the primitive at the position where the field state is referenced or the change in the state. It can be expressed realistically.

The image generation system, the program and the information storage medium according to the present invention include means for detecting a given event (which stores a program which causes a computer to function as the means or causes the computer to function as the means. ), The field setting means changes and sets at least one of the size, division number, setting position, setting number and shape of the field based on the detection result of the event.

According to the present invention, by appropriately changing the size of the field upon the occurrence of a given event, the real factors reflecting the interactive external factors are reflected without increasing the processing load of the simulation. It becomes possible to generate various images in real time.

Further, the image generation system, the program and the information storage medium according to the present invention are characterized in that the field or a virtual field influenced by the field is set at a position associated with the event.

Here, the position associated with an event means a position determined in correspondence with each detected event, and for example, there is a position where an event factor occurs.

The field or the influence of the field is not limited to the field for the physical quantity directly obtained by the simulation, but also for the spatial information about the information that changes based on the physical quantity directly obtained by the simulation. It is meant to include a region.

According to the present invention, the field size and the like can be optimized according to the event that has occurred, so that the processing load and the realistic image generation can be optimized more efficiently. .

Further, the image generation system, the program and the information storage medium according to the present invention are characterized in that the position where the event occurs and the position where the field or the virtual field influenced by the field is set are different. .

According to the present invention, it is not necessary that the position to which the state of the field or the virtual field affected by the field is referred to be the same as the position to which the state is applied, so that various positions can be used in various situations. You will be able to apply it to effects.

Further, in the image generating system, the program and the information storage medium according to the present invention, the information of one field where the simulation calculation is performed is the information of the field set at a plurality of positions in the object space or the information of the field. It is characterized by being used as affected information.

According to the present invention, the result obtained by the simulation in one field can be reflected in the primitives arranged at each position, so that a realistic and unprecedented expression can be processed with less processing. It can be realized under load.

Further, in the image generation system, the program and the information storage medium according to the present invention, the field or the virtual field affected by the field is set at a position that follows a primitive moving in the object space. Characterize.

According to the present invention, by following the primitive, it is not necessary to set a wide space for calculation. In addition, it is possible to generate a real-time image that reflects, for example, the moving method of moving primitives (objects) and the moving speed in real time without monotonizing the expression of the effect by moving the primitives or objects in the object space. .

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings.

The present embodiment described below does not limit the content of the present invention described in the claims. Further, not all of the configurations described in the present embodiment are essential as the solving means of the present invention.

1. Configuration FIG. 1 shows an example of a functional block diagram of an image generation system (game system) of this embodiment.

In the figure, this embodiment may include at least the processing unit 100 (or the processing unit 100 and the storage unit 170, or the processing unit 100, the storage unit 170 and the information storage medium 180). Other blocks (for example, the operation unit 160, the display unit 190, the sound output unit 19
2. The portable information storage device 194 and the communication unit 196) may be arbitrary constituent elements.

Here, the processing section 100 performs various processing such as control of the entire system, instruction of commands to each block in the system, game processing, image processing, sound processing, etc., and its function is: Various processors (CPU, DSP
Etc.) or hardware such as ASIC (gate array etc.) or a given program (game program).

The operation section 160 is for the player to input operation data, and its function can be realized by hardware such as a lever, a button, a microphone, or a case.

The storage unit 170 includes the processing unit 100 and the communication unit 1.
A work area such as 96, whose function is RAM
It can be realized by hardware such as.

An information storage medium (a storage medium usable by a computer) 180 stores information such as programs and data, and its function is that of an optical disc (C
D, DVD), magneto-optical disk (MO), magnetic disk, hard disk, magnetic tape, or memory (RO
It can be realized by hardware such as M). Processing unit 10
0 performs various processes of the present invention (this embodiment) based on the program (data) stored in the information storage medium 180. That is, the information storage medium 180 stores a program for causing a computer to realize (execute, function) the means of the present invention (the present embodiment) (particularly, the blocks included in the processing unit 100). Alternatively, it includes a plurality of modules (including objects in object orientation).

A part or all of the information stored in the information storage medium 180 will be transferred to the storage unit 170 when the system is powered on. The information storage medium 1
80 includes a program for performing the process of the present invention, image data, sound data, shape data of a display object, information for instructing the process of the present invention, or information for performing the process according to the instruction. Can be made.

The display unit 190 outputs the image generated by the present embodiment, and its function is CRT,
LCD or HMD (head mounted display)
It can be realized by hardware such as.

The sound output unit 192 outputs the sound generated by this embodiment, and its function can be realized by hardware such as a speaker.

The portable information storage device 194 stores player's personal data, game save data, and the like. As the portable information storage device 194, consider a memory card, a portable game device, or the like. You can

The communication unit 196 performs various controls for communicating with the outside (for example, a host device or another image generation system), and its function is various processors or communication ASICs. It can be realized by the hardware or the program.

A program (information) for realizing (execution, function) each means of the present invention (this embodiment) is information from an information storage medium of a host device (server) via a network and a communication unit 196. It may be delivered to the storage medium 180. Use of such an information storage medium of the host device (server) is also included within the scope of the present invention.

The processing unit (processor) 100 is the operation unit 1
Various processing such as game processing, image generation processing, or sound generation processing is performed based on operation data from 60, programs, and the like. In this case, the processing unit 100 includes the storage unit 17
Various processes are performed by using the main storage unit in 0 as a work area.

Here, as the processing performed by the processing unit 100, coin (price) acceptance processing, various mode setting processing, game progress processing, selection screen setting processing, objects (one or more primitives. The same applies to the description) processing for obtaining the position and rotation angle (rotation angle around the X, Y or Z axis), processing for moving the object (motion processing), position of the viewpoint (position of the virtual camera) and line-of-sight angle (virtual camera). Rotation angle), processing for arranging objects such as map objects in the object space, hit check processing, processing for computing game results (results, results), for allowing multiple players to play in a common game space Processing, game over processing, or the like can be considered.

The processing section 100 includes a simulation calculation section 110, a field setting section 115, a primitive processing section 120,
Processing monitor 125, image generator 140, sound generator 150
including. Note that the processing unit 100 does not need to include all of these functional blocks 110 to 150, and may have a configuration in which some functional blocks are omitted.

Here, the simulation calculator 110 is
Elapsed time at each point (lattice point in a narrow sense) of a two-dimensional or three-dimensional simulation space (game space, virtual space) (elapsed virtual time, elapsed real time, or progressing frame)
Physical quantities (such as velocity, acceleration, force, position, temperature,
Change of electricity or magnetism etc. is obtained by simulation calculation, and the flow field (fluid field, velocity field,
An acceleration field, a vector field) or a virtual field affected by the flow field is obtained. More specifically, the simulation calculation unit 110 obtains flow field information (for example, velocity vector, acceleration vector, temperature change) indicating a change in the flow field in a two-dimensional or three-dimensional simulation space by a fluid simulation calculation. Alternatively, the simulation calculation unit 110 may change the information based on the flow field information about the obtained physical quantity (for example, velocity vector) at each point (for applying to the object, the flow field information about the physical quantity may be used). A field that is a result of calculation based on, for example, position information, velocity information, temperature information, physical quantity, etc.) is obtained as a virtual field affected by the field of the physical quantity.

Here, the fluid simulation means, for example, numerically modeling and expressing a stationary state or a motion state of a fluid such as a liquid or gas which changes its shape with respect to an external force and flows. .

The flow field (field in a broad sense) is a region where the above-mentioned physical quantity indicating the stationary state or the operating state of the fluid is spatially distributed. For example, the state of the flow field can be represented by dividing the simulation space of the fluid simulation into a grid shape and determining the physical quantity at each grid point. Then, by performing a fluid simulation calculation in accordance with the passage of time (frame progression), it is possible to give each grid point a physical quantity according to its position and time, and to represent a change in the state of the flow field. Therefore, the virtual field affected by the flow field can be represented by obtaining information at the same grid point or another grid point calculated based on the physical quantity at each grid point of the flow field.

The field setting unit 115 performs a process of setting the flow field obtained by the simulation calculation unit 110 or the virtual field affected by the flow field in the object space.

Here, the object space means a virtual three-dimensional space in which primitives whose shapes are specified by, for example, definition points (vertex of polygons or control points of free-form surface) are arranged.

More specifically, the field setting unit 115 sets the obtained flow field or the virtual field influenced by the flow field at an arbitrary position in the object space, or the object placed in the object space. (In a broad sense, it is a primitive). At that time, the field setting unit 115 can change at least one of the size of the flow field, the number of divisions performed in a grid, the setting position, the setting number, and the shape (field or grid shape). ing.
The field setting unit 115 can set a plurality of fields (flow fields) or a virtual field influenced by the fields at a plurality of positions in the object space, and can also set one field (flow field) or the influence of the fields. The received virtual field can be set at a plurality of positions in the object space. The flow field set by the field setting unit 115 or the virtual field affected by the flow field may be two-dimensional or three-dimensional.

The field setting unit 115 may set a flow field or a virtual field influenced by the flow field from the start of a series of object image generation processing. The place may be temporarily set only when it is detected.

The primitive processing unit 120 arranges a two-dimensional flow field obtained by the simulation calculation unit 110 or a virtual field affected by the flow field in a three-dimensional object space (consisting of primitives. Objects and particle primitives). The primitive reflected by the primitive processing unit 120 may be two-dimensional or three-dimensional.

More specifically, the primitive processing unit 12
0 is information on the position of the primitive or information associated with the primitive (color information, transparency information) using information on the field obtained by the simulation calculation unit 110 or information affected by the field for the primitive before simulation. Etc.) and the information (lifetime, size, color information, transparency information, density, etc.) associated with the position of the particle (particle primitive) and the particle is updated. As a result, the primitive processing unit 120
For example, the position of the particle can be changed according to the velocity vector as the information of the flow field, and the life and color information of the particle can be changed according to the temperature information obtained as the information of the flow field.

Further, the primitive processing unit 120 uses the flow field information to perform billboard processing on the primitive whose operation or state is updated. More specifically, the primitive processing unit 120 sets the primitive surface of the updated primitive so as to be substantially perpendicular to, for example, the virtual camera (the direction of the line of sight, the line of sight vector), and creates a texture representing an effect or the like. Perform mapping process.

Therefore, by changing the texture representing the effect or the like according to the updated flow field information of the flow field, the change in the operation or state of the two-dimensional flow field obtained by the fluid simulation is calculated in three dimensions. Can be represented as an object image viewed from a virtual camera (given viewpoint) in the object space of.

The process monitoring unit 125 performs a process of detecting the occurrence of a given event or monitoring the load of various processes performed in the processing unit 100. For example, the field setting unit 115 changes the size of the field to be set, etc., based on the event detected by the process monitoring unit 125. Further, the processing monitoring unit 125 is, for example, the processing unit 1.
The load is calculated for each processing performed at 00, and it is determined that the processing load is high when the load exceeds a given threshold. Then, for example, when the processing monitoring unit 125 determines that the processing load is high, the field setting unit 115 changes the size of the field to be set or the like.

The image generation section 140 performs image processing based on the results of various processing performed by the processing section 100 to generate a game image and outputs it to the display section 190. For example, in the case of generating a so-called three-dimensional game image, geometry processing such as coordinate conversion, clipping processing, perspective conversion, or light source calculation is performed first, and based on the processing result, primitive data (primitive configuration points Position coordinates of (vertices) or control points, texture coordinates, color (luminance) data, normal vector or α value, etc.) are created. Then, based on this primitive data (primitive data such as polygon, free-form surface or subdivision surface), the image of the object (one or more primitives) after the geometry processing is stored in the storage unit 17.
It is drawn in a drawing buffer of 0 (a buffer that can store image information in pixel units such as a frame buffer and a work buffer). As a result, an image viewed from the virtual camera (given viewpoint) in the object space is generated.

In the present embodiment, the image generator 140
Performs image generation processing based on the flow field obtained by the simulation calculation unit 110 or the virtual field affected by the flow field. More specifically, the flow field or information of the flow field obtained by the simulation calculation unit 110 is first set in the object space by appropriately changing the size and the like by the field setting unit 115. At this time, the size and position of the flow field may be determined based on the monitoring result of the process monitoring unit 125. Then, the primitive processing unit 120 uses the primitives (including the texture-mapped primitives) in which the flow field or the virtual field affected by the flow field is reflected, and the image generation unit 140 uses the irregular shape (water, Cloud, fog, smoke, air flow, electromagnetic waves, flames, etc.) is generated. For example, particles were generated in the direction of the velocity vector starting from each point (lattice point) of the obtained flow field, or a texture corresponding to the change in the temperature distribution at each point of the obtained flow field was mapped. Generate an image of a primitive. Further, for example, an image of the object that reflects the state of each point (lattice point) in the field mapped to the object arranged in the object space is generated.

The sound generation section 150 performs various kinds of sound processing according to the result of the game processing, generates sounds such as BGM, sound effects, and voice, and outputs them to the sound output section 192.

The functions of the simulation calculation unit 110, the field setting unit 115, the primitive processing unit 120, the processing monitoring unit 125, the image generation unit 140, and the sound generation unit 150 are as follows.
All of them may be realized by hardware, or all of them may be realized by a program. Alternatively, it may be realized by both hardware and a program.

The image generation system of this embodiment is
The system may be a system dedicated to the single player mode in which only one player can play, or a system having not only such a single player mode but also a multiplayer mode in which a plurality of players can play.

When a plurality of players play,
The game image and the game sound to be provided to the plurality of players may be generated using one terminal, or a plurality of terminals (game machine, mobile phone) connected by a network (transmission line, communication line) or the like. ) May be used.

2. Features of this Embodiment Next, features of this embodiment will be described with reference to the drawings.
In the following, a case where a fluid simulation calculation is performed using a flow field (velocity field, velocity field, fluid field, vector field) will be mainly described as an example. However, the present invention is not limited to the flow field, and can be applied to an image expression that reflects various fields other than the fluid expression.

2.1 Flow Field In this embodiment, for example, an image in which the operation result of the fluid simulation is reflected in the operation of the primitive (including the particle primitive) arranged in the object space is generated.

In the fluid simulation, when the calculation is performed in a three-dimensional space, the amount of calculation becomes enormous, so that it is difficult to perform real-time processing of interactively generating an image reflecting external factors. Here, the real-time processing means, for example, all processing such as game processing, image generation processing, and sound generation processing in one frame (1/60 second, 1
/ 30 seconds).

Therefore, in this embodiment, a fluid simulation is performed on a two-dimensional plane without considering the depth to obtain a flow field, or a virtual field affected by the flow field (flow field information or the influence of the flow field). The flow rate information or the information affected by the flow field is applied to the three-dimensional object space to reduce the processing load and enable real-time processing.

If the flow field or the virtual field affected by the flow field is set so as to cover the entire object space, the simulation space becomes large,
Real-time processing becomes impossible.

Therefore, in the present embodiment, the flow field or the virtual field affected by the flow field is mapped only to the place where the representation of the irregular image by the fluid simulation is required (flow field information or the flow field The affected information is mapped) to reduce the processing load of the fluid simulation. Mapping the flow field or the virtual field affected by the flow field can be synonymous with mapping the information of the flow field or the information affected by the flow field.

Furthermore, even when it is not necessary to generate an image reflecting the flow field as described above, it is not efficient to perform the fluid simulation in each frame. When it is not necessary to generate an image that reflects the flow field, it is desirable to allocate the processing load for that to other processing.

Therefore, in this embodiment, at least one of the size, the number of divisions, the setting position, the setting number, and the shape of the flow field set in the object space is made variable.

With this, external factors that are generated interactively are reflected without impairing the expressiveness of the realistic image generated based on the flow field, and the constituent points of the object in the flow field, the constituent points of the free-form surface or the control are controlled. Since the position or state of points or particles can be changed,
It will be possible to represent movements of objects, state changes (including deformation), etc. that have never been seen before.

The flow field (field in a broad sense, the same applies in the following description) is generated by dividing the simulation space (game space, virtual space) into an appropriate number in a grid pattern. Flow field information at each grid point (each point in a broad sense. The same applies in the following description) that changes with the passage of time (frame progression) due to a fluid simulation calculation (a simulation calculation in a broad sense. The same applies to the following description). (For example, a velocity vector) is obtained, and the field information is updated.

In the fluid simulation, the physical quantity to be obtained has temporal and spatial continuity under given boundary conditions, and the influence of a given external force (external factor) directly or indirectly on the flow field. It is done by a given formula that can affect all grid points. When simulating the motion of a continuum such as water or air, the incompressible Navi
The flow field can be calculated using the er-Stokes equation.

Next, a procedure for performing fluid simulation (fluid dynamics calculation) will be described.

Space for simulating fluid (flow field)
After setting the state at a certain moment (for example, a certain frame), the Navier-Stokes equation or the like is solved to obtain the state of the flow field at the next moment (the next frame).

FIG. 2 shows a schematic diagram for explaining the procedure when performing fluid calculation. Further, FIG. 3 shows a flowchart for explaining the procedure when performing the fluid simulation calculation.

A1 in FIG. 2 is a flow field H at a certain moment.
2 schematically shows the state of F, and A2 in FIG.
It is a schematic representation of the state of the flow field HF at the next moment. In FIG. 2, the state of the flow field HF is the velocity vector (FV1, FV2, FV3 ...) Set at each grid point (GP1, GP2, GP3 ...) At a certain time.
-) Can be represented.

Although the flow field HF is shown two-dimensionally in FIG. 2 in order to make it easier to see, the flow field may be three-dimensional. In addition, in FIG. 2, each grid point (GP
1, GP2, GP3 ...) and velocity vector (FV1,
Although the start points of FV2, FV3 ...) Are shifted, they may be the same.

When obtaining the state of A2 from the state of A1 in FIG. 2, fluid calculation (fluid dynamics calculation) is performed in the procedure as shown in FIG.

First, for each grid point (grid point) in the simulation space, at a certain moment (frame "N-
1)), the flow field information (for example, velocity vector) is set (step S1. See A1 in FIG. 2). That is, the initial condition of the fluid simulation is set.

Next, fluid calculation is performed based on the flow field information set at each grid point (step S2).

Then, the flow field information of each grid point obtained by the fluid operation becomes flow field information (information of each grid point) representing the flow field at the next moment (frame "N") (step S3, FIG. 2 A2).

After that, the flow field information of each grid point obtained in step S3 is set as the flow field information of each grid point in step S1 (initial condition of fluid simulation), and the fluid of step S2 is set again. It is possible to change the state of the flow field by performing the calculation recursively.

Since the initial condition (step S1) can be basically set freely, it is also possible to apply an external force (eg velocity vector) to an arbitrary point at an arbitrary time.

In order to reflect the external force in the flow field, the corresponding grid point (for example, the grid point close to the position to which the external force is applied)
On the other hand, flow field information corresponding to an external force (for example, when the external force is a velocity vector, a velocity vector having a magnitude and a direction corresponding to the external force) may be given.

In FIGS. 4A, 4B, and 4C, the flow field H
The figure which represents typically the state change of the field when the velocity vector EFV corresponding to an external force is given with respect to F is shown.

In FIGS. 4 (A), 4 (B) and 4 (C), the grid points and the start points of the velocity vectors are shifted for the sake of clarity, but they may be the same.

For example, if a velocity vector EFV corresponding to an external force as shown in FIG. 4 (B) is given to the flow field HF as shown in FIG. 4 (A), after fluid calculation, as shown in FIG. 4 (C). Such a flow field HF can be obtained.

Here, as a method of reflecting the external force in the fluid simulation, for example, a method of giving a velocity vector EFV obtained according to the direction and magnitude of the external force to the nearest grid point of the position to which the external force is applied as an initial condition. Can think of. Alternatively, the velocity vector EFV obtained in the magnitude and direction of the external force may be distributed to the lattice points GP13, GP14, GP18, GP19 around the position to which the external force is applied and given as the initial condition.

By applying the external force to the flow field in this way, it becomes possible to make the simulation space in which the fluid operation is performed interactive.

Next, the boundary conditions when setting the flow field will be described. Here, how to give flow field information (for example, velocity vector) at the boundary of the space to be simulated is called a boundary condition.

The boundary condition is a very important factor in performing a fluid simulation, and various behaviors of a fluid can be virtually reproduced only by changing the way of giving this value.

For example, if the direction of the velocity vector at the lower boundary is set to be downward, it is possible to virtually express a fluid that moves like river water flowing from top to bottom.

If all the values at the boundary are set to 0,
It is possible to virtually express the movement of fluid in a closed space such as the surface of a bathtub in a bathroom, and to express how the fluid swirls.

For example, as shown in FIG. 5, if a velocity vector that blows upward is set as the boundary condition at the lower end, it is possible to generate a field in which gas always flows from bottom to top.

If left in this state, a steady flow will be obtained after a while, and the merit of performing the fluid simulation will diminish. However, by using the fluid simulation, it is possible to easily express the influence of the flow field to which an external factor such as “send the wind” is added.

2.2 Fluid simulation using the Navier-Stokes equation The equation governing the motion of a continuum such as water or air is Navi
Called the er-Stokes equation. If the fluid flow is sufficiently smaller than the speed of sound, incompressibility may be assumed, and the Navier-Stokes equation in this case is as follows.

[0100]

[Equation 1]

Where V is the flow velocity, p is the pressure, ρ is the density,
μ is the viscosity of the fluid. Further, ∇ represents a gradient operator and Δ represents Laplacian.

By differentiating these equations, the solution at each lattice point can be obtained numerically. The space to be analyzed by the difference is divided into a flow field (fluid field, vector field) in a grid shape, and each grid point is provided with flow field information (for example, velocity vector) for calculation.

Hereinafter, an example of the method of making a difference will be specifically described.

(E1) is a partial differential equation representing the law of conservation of mass, and is called "equation of continuity". Further, (E2) represents the law of conservation of momentum, and is called (Narrowly defined) Navier-Stokes equation.

In this equation, a typical length of the flow is L, and a typical velocity is U.

[0106]

[Equation 2]

Substituting these into (E1) and (E2) leads to the following equation.

[0108]

[Equation 3]

Re is a Reynolds number and is a dimensionless parameter defined by the following equation.

[0110]

[Equation 4]

There is only one parameter that appears in this equation, and when no external force acts, the flow changes according to the Reynolds number.

From the definition, the fact that the flow velocity is small, the scale of the flow is small, and the viscosity is large are all
It has the same effect in the sense of reducing the ynolds number.

The Reynolds number physically represents the ratio of the inertial force to the viscous force, and the small Reynolds number means that the viscous force is superior to the inertial force. That is, it intuitively becomes a viscous fluid flow.

The following equations can be obtained by replacing the variables (E1) 'and (E2)' with x, V, t, and p.

[0115]

[Equation 5]

The expressions (E3) and (E4) are given by the following (1)
Characteristic such as (3) is expressed. (1) The second term on the left side of the equation (E4) is non-linear. (2) The derivative of the highest rank is the second rank of the second term on the right side of the equation (E4) and further includes a parameter. (3) The velocity V is a time evolution type, but the pressure p is not a time evolution type.

In particular, (3) is a problem peculiar to incompressibility and is a factor that makes the numerical solution of the Navier-Stokes equation difficult. That is, when the velocity V is obtained over time, it is necessary to determine the pressure p so as to satisfy the continuous equation (E3) at each time step.

As a method for numerically solving the incompressible Navier-Stokes equation, the method of independently obtaining pressure is adopted as follows.

In equation (E4), if the divergence of both sides is taken,

[0120]

[Equation 6]

Setting D = ∇V gives the following.

[0122]

[Equation 7]

According to the equation (E3) of continuity, D = 0 should be obtained, but when the difference (E5) is solved, the discretization error may be accumulated and D may be a large value. , I left it on purpose. Now, in (E5), the pressure distribution obtained with D = 0 satisfies the following equation.

[0124]

[Equation 8]

However, (E6) does not necessarily mean D = 0. It can be seen from the fact that D = constant (≠ 0) satisfies (E6). If D = 0 is always satisfied on the boundary and the initial condition is given so that D = 0 is satisfied in all the regions, the formula (E6) means D = 0. Have difficulty.

Therefore, the equation (E5) is first discretized with respect to t.

[0127]

[Equation 9]

If D ^{n + 1} = 0 is set here, (E5) is as follows.

[0129]

[Equation 10]

Even if D ⁿ ≠ 0, p obtained in this way is determined so that D ^{n + 1} = 0. Therefore, p is always D with respect to inaccuracy of boundary conditions and error accumulation due to time progress.
Can be kept small.

If the pressure is determined from the expression (E7), the expression (E
By substituting the pressure into 4), it becomes possible to obtain V over time. This method is generally called the MAC method.

At (E7), since Δt is sufficiently small, it can be regarded as α = 0.

Therefore, in order to solve the incompressible Navier-Stokes equation, the following two equations must be solved.

[0134]

[Equation 11]

As a two-dimensional Cartesian coordinate system, (E
8) and (E9) are displayed as components as follows.

[0136]

[Equation 12]

The equation (E10) is the Poisson equation regarding pressure.

Regarding the equations (E11) and (E12), the following equations can be used for the respective nonlinear terms uu _x + vu _y and uv _x + vv _y .

[0139]

[Equation 13]

Now, the cavity problem will be taken up as an example of the calculation.

FIGS. 6A, 6B, and 6C are diagrams used for explaining a specific calculation example.

The cavity problem referred to here is shown in FIG.
Consider a fluid that fills a square region like (A),
This is to numerically obtain the movement of the fluid inside when moving rightward on DC at speed 1.

First, considering the boundary condition of velocity, AD,
U = v = 0 on AB and BC, and u = 1 and v = 0 on CD.

Next, consider the boundary condition of pressure.

In the equation (E9), V =
When 0 is substituted, the following formula is established.

[0146]

[Equation 14]

This equation holds u = 0 along the y direction on AD and BC, and therefore the following equation holds.

[0148]

[Equation 15]

On AB and CD, v along the x direction
Since = 0, the following equation holds.

[0150]

[Equation 16]

Here, a grid called a staggered grid is used for the differentiation. This is because, as shown in FIG. 6B, the definitions of the individual physical quantities are not the same, and on the contrary, the lattice in which all the physical quantities are defined at the same point is called a regular lattice.

As can be seen from FIG. 6B, one advantage of the staggered grid is that a continuous expression can be naturally expressed in one grid cell, and the pressure gradient in each direction determines the velocity in that direction. The point is that the properties of the Stokes equation can be expressed naturally.

Specifically, the following formula is established by approximating the formula of continuity in the cell of FIG. 6 (B).

[0154]

[Equation 17]

As a point to be noted when solving the Navier-Stokes equation using a staggered lattice, for example, when considering the equation for u, the following terms appear in the equation.

[0156]

[Equation 18]

Originally, v in this term should take a value at the defining point of u, but when a staggered grid is used, the value of v is not defined at that point. Therefore,
It is necessary to somehow determine the value from the definition point of v. Here, it is determined by the average value of surrounding points.

That is, in the case of the previous example, it is as follows.

[0159]

[Formula 19]

The same applies to the equation concerning v.

Also, the Poisson equation (E1 regarding pressure)
Similar processing is performed on the right side of 0).

Now that the conditions necessary for solving the Navier-Stokes equation have been set, the rest of (E10),
(E11) and (E12) may be differentiated and calculated.

As a precaution, the difference results will be shown below.

[0164]

[Equation 20]

In each of the expressions, the upper subscript n is omitted.

The procedure for solving the equation is as follows: The Poisson equation of (F1) is solved from the initial condition of the velocity or the velocity at the previous time step to obtain the pressure, and the pressure and the velocity are used (F2). , (F3), and the speed at the next time step is obtained. By repeating this procedure, it becomes possible to obtain a solution in a time evolution manner.

In the present embodiment, (F1) to (F3) are solved for each grid point forming the flow field (fluid field, vector field) to obtain the velocity vector given to each grid point.

Here, (F1) is an equation for obtaining the pressure, (F2) is an equation for obtaining the velocity in the x direction,
(F3) is an equation for obtaining the velocity in the y direction. I and j are two-dimensional flow fields (fluid field, vector field).
Is a subscript representing the x and y coordinates of each grid point in. The subscript n + 1 of u means the value of u at the next moment.

In this embodiment, when the velocity vector given to the flow field based on an external factor is reflected in the fluid simulation calculation, the x component of the velocity vector is used as u _{ij in the} equation (F2), and (F3 ), The y component of the velocity vector may be used as v _ij .

Finally, the boundary condition will be described.

Regarding the boundary condition of velocity, the wall surface is shown in FIG.
At the position shown in (C), u _W= 0.

Regarding the boundary condition of the pressure, for example, if the pressure at the virtual point P is p ', from the equation (E14),
It looks like this:

[0173]

[Equation 21]

The second-order differential of the velocity needs to be evaluated at the point W in the figure, but it is as follows when it is approximated by the one-sided difference of the first-order accuracy.

[0175]

[Equation 22]

The value of u at the virtual point A is required for approximation by the central difference. In this case, u _A = u _B.
When v needs a value at a virtual point, v _D = -v _E
Take (At this time, if v _W is the average of four surrounding points, v _W = 0 holds.) 2.3 Application of two-dimensional flow field to three dimensions As described above, in the present embodiment, the fluid simulation is performed. Based on the information of the two-dimensional flow field obtained by
Primitives (including particle primitives forming a particle system) whose positions and states (information associated with (related to) primitives such as color (luminance) and transparency) are controlled are arranged in a three-dimensional object space.

FIG. 7 schematically shows the relationship between the two-dimensional flow field and the three-dimensional object space in this embodiment.

That is, in this embodiment, Navier-Stoke
As the information of the two-dimensional flow field HF obtained by the fluid simulation using the s equation, the flow field information (for example, velocity vector) obtained for each grid point or the information affected by the flow field is used to The position (including the constituent points and control points of the object) and information associated with the primitive (for example, color (luminance), α value, etc.) are obtained and reflected in the primitive. And
The primitives thus obtained are arranged in a three-dimensional object space, and a given viewpoint (virtual camera) VC
Generate an object image visible from.

More specifically, by using the information on the flow field or the information affected by the flow, for example, the position, color, or transparency of the constituent points of the object in the flow field HF is changed, or the object is changed. The weight, which is the information associated with the control point of (for example, the control point of NURBS), is changed.

As a result, the load of fluid calculation for realistically expressing a natural phenomenon such as a flame is reduced, and an image in which an external factor (for example, a velocity vector EFV corresponding to an external force) interactively reflected is reflected in real time. Will be able to generate.

The actual flow field is shown in FIGS. 2, 4 and 5.
It is divided into a grid shape as described in 1. and has flow field information (velocity vector) at each grid point. However, if there is no particular problem for the convenience of explanation, it occurs in the flow field for easy viewing. Only the flow is schematically illustrated.

FIG. 8 shows an example of an object image when the two-dimensional flow field described above is applied to the expression of a bonfire flame.

Here, the case where a bonfire flame is represented by a particle system is shown. In this way, the particles PT generated from the center of the bonfire are
By updating the position and state in the two-dimensional flow field HF and displaying the image of the flame as a texture on the particle PT and displaying the texture, it is possible to express the state of the flame burning brilliantly.

In this case, the position of the particle generated from the position of the external cause is set by setting the position of the external factor generated interactively as the center of the bonfire and setting the direction of the velocity vector corresponding to the external force as the external factor upward. Refers to the state of the flow field and gradually diffuses, and the information (color and α value) associated with the particles gradually changes with reference to the state of the flow field to express a more realistic flame.

Further, by reflecting such a flow field or a virtual field affected by the flow field in the positions of the constituent points or control points of the primitive, it is possible to deform the primitive. Furthermore, information related to the flow field or the virtual field affected by the flow field (for example, color information, transparency information, etc.) or information related to the control point of the primitive (for example,
It is possible to express the color change and the transparency change according to the fluid simulation by reflecting the change in the weighting etc.), and it is possible to change the image which could not be expressed so far.

Further, based on the information of the flow field HF affected by the externally generated interactive factor or the information affected by the flow field, the primitive whose normal vector is changed in direction and size is generated. The associated normal vector may be obtained. When shading an object using a normal vector associated with such a primitive, it is possible to generate an image in which shading changes according to external factors.

Furthermore, in order to reflect the change of the flow field in the position and state of the primitive in the three-dimensional object space, the sprite polygon (in a broad sense) is placed at the position of the primitive (particle primitive) that reflects the two-dimensional flow field. May be arranged.

Here, the sprite polygon is a billboard-processed polygon. Further, the billboard processing means processing to always face the direction of the virtual camera.

As a result, even if the position of the virtual camera is changed, the two-dimensional plane (flow field) always faces the direction of the virtual camera.
A primitive moves above, and a billboard-processed sprite polygon is placed at the position of this primitive. Therefore, the load of drawing processing can be reduced by reducing the number of polygons and texture mapping.

2.4 Mapping Two-Dimensional Flow Field to Three-Dimensional Object Further, in the present embodiment, the flow field obtained by the fluid simulation or the virtual field affected by the flow field is associated with the mapped object. Primitives in the flow field (including the particle primitives that make up the particle system) at the specified position (for example, the position around the object or the surface that is affected by the flow field) (in a broad sense, another primitive) An image that reflects the fluid motion is generated.

The flow field to be mapped or the virtual field affected by the flow field may be two-dimensional or three-dimensional. However, in the case of two-dimensional, the processing load is increased by that amount as described above. Can be reduced. The object to which the flow field or the virtual field affected by the flow field is mapped may be two-dimensional or three-dimensional.

FIG. 9 schematically shows a field mapped to an object in this embodiment.

Here, the case where the two-dimensional flow field HF is mapped to the three-dimensional object is shown.

In this embodiment, the above-mentioned Navier-Stokes is used.
The flow field HF obtained by the fluid simulation using the equation is mapped to the object OBJ arranged in the object space.

The flow field HF can be obtained, for example, by obtaining the flow field information (for example, velocity vector) at the position of each grid point divided into a grid by a fluid simulation calculation using the Navier-Stokes equation. .

Therefore, by mapping the flow field HF thus obtained on the surface of the object OBJ, for example, the change of the position of the primitive in the flow field HF and the color information as the information associated with the primitive, The motion of the fluid can be reflected in the change in the state of the primitive due to the transparency information. That is,
The position and state of the primitives in the flow field HF can be controlled according to the fluid simulation.

For example, in the case of expressing sweat flowing down a human arm, by mapping the flow field HF on the surface of the arm object and controlling the position and state of the sweat object on the surface of the arm object according to the fluid simulation, it is possible to realize realistically. Can be expressed. Also, for example, when expressing water drops flowing down the windshield of a car,
By mapping the flow field HF on the surface of the windshield object and controlling the position and state of the water drop object on the surface of the windshield object according to the fluid simulation, it is possible to realistically represent.

The virtual field affected by the flow field can be reflected in the object by similarly mapping.

Further, for example, when the flow field HF is mapped on the surface of the object OBJ by UV mapping, the flow field HF can be mapped on the surface even when the shape of the object OBJ changes.
Regardless of the shape of the surface of the object OBJ, the position or state of the primitive can be controlled according to the fluid simulation.

In FIG. 10, in the present embodiment, the U of the two-dimensional flow field HF performed on the object OBJ1.
The figure for demonstrating V mapping is shown.

Here, the vertex coordinates of the object OBJ1 are (X, Y) = (0, 0), (Xmax, 0), (0,
Ymax), (Xmax, Ymax). For such an object OBJ1, the vertex coordinates of the flow field HF subjected to UV mapping are (U, V) =
Let (0,0), (1,0), (0,1), (1,1).

In UV mapping, for example, each vertex of the flow field HF is associated with each vertex of the object OBJ1. That is, at the vertex coordinates (X, Y) = (0, 0) of the object OBJ1, the vertex coordinates (U,
V) = (0,0) to the vertex coordinates (X, Y) = (Xmax, 0) of the object OBJ1 and the vertex coordinates (U, V) = (1,0) of the flow field HF to the vertex of the object OBJ1. At the coordinates (X, Y) = (0, Ymax), the vertex coordinates (U, V) = (0,1) of the flow field HF are set to the object OBJ.
The vertex coordinates (U, V) = (1,1) of the flow field HF are coordinated with the vertex coordinates (X, Y) = (Xmax, Ymax) of 1.

Thus, when the object OBJ1 is drawn, each point of the object OBJ1 is flow field HF.
Since it is possible to determine which position in the flow field HF is being referred to, when a velocity vector is obtained as the flow field information of each point, the velocity vector of the grid point GP of the flow field HF corresponds to the surface of the object OBJ1. It can be the velocity vector of the position GP '. As a result, the position or state of the primitive on the surface of the object OBJ1 can be changed.

FIG. 11 shows the flow field HF on the surface of the object.
An example of the object image to which is mapped is shown.

Here, the objects OBJ2 and OBJ3 are arranged in the object space, and the flow field HF is mapped on the surface of each by UV mapping.
In FIG. 11, the velocity vector obtained for each grid point of the flow field is indicated by an arrow.

As described above, since the flow field HF can be mapped on the surface of the object to be mapped, the position and state of the primitive on the object surface are calculated based on the flow field information obtained according to the Navier-Stokes equation. Can be changed and expressed.

As described above, the flow field HF or the virtual field influenced by the flow field can be arranged at an arbitrary position of the object arranged in the object space. Therefore, since it is only necessary to perform mapping on a place where an irregular image is to be represented by the fluid simulation, it is possible to reduce the processing load of the fluid simulation. In addition, the position or state of the primitive reflecting the fluid motion can be changed on the surface of the object, and it becomes possible to generate an unprecedented realistic image.

2.4.1 Operation in Mapped Flow Field In this embodiment, the flow field HF or the virtual field affected by the flow field is mapped to an object to perform the following expression. be able to. The case of mapping a flow field will be described below, but the same expression can be applied to the case of mapping a virtual field affected by the flow field.

For example, the direction and size of the normal vector associated with the object to which the flow field HF is mapped, and the vertex information (color information, transparency information, position information) of the object can be changed.

12 (A) and 12 (B), in order to explain the case where the normal vector associated with the object to which the flow field HF is mapped in this embodiment is changed based on the information of the flow field HF. The figure is shown.

The flow field HF is mapped on the surface of the object, and as shown in FIG.
In the GPO4, velocity vectors VV1 to VV are used as flow field information.
It is assumed that V4 is required.

For example, the grid points GPO1 to GPO of the flow field HF
If the vertices of PO4 and the object match, the normal vector NVO associated with the object
1 to NVO4 as velocity vectors VV1 to VV4
You may make it change according to the magnitude | size of. Also,
Even if the grid points GPO1 to GPO4 of the flow field HF and the vertices of the object do not match, the magnitudes of the normal vectors NVO1 to NVO4 associated with the object are changed by the ratio of the magnitudes of the velocity vectors VV1 to VV4. You may allow it.

Alternatively, the direction of the normal vectors NVO1 to NVO4 associated with the object is changed according to the direction of the velocity vectors VV1 to VV4, and the normal vectors NVO1 'to NVO4 associated with the object are changed.
′ May be generated.

As a result, when shading an object using the normal vectors NVO1 'to NVO4' associated with such an object, it is possible to generate an image in which the shading of the surface of the object changes, which has never been seen before. it can. In addition, when grass grows in the direction of the normal vector on the surface of the ground object having the shape of the undulating ground, the normal vectors NVO1 ′ to NVO4 associated with the object by wind or gust added as an external factor. 'Is generated. Therefore, it is also possible to express grass fluttering in the wind using the normal vectors NVO1 'to NVO4' associated with this object.

FIGS. 13A and 13B are views for explaining the case where the position of the vertex of the object onto which the flow field HF is mapped in this embodiment is changed based on the information of the flow field HF. Show.

A flow field HF is mapped on the surface of the object, and grid points (vertices) G are formed as shown in FIG.
Velocity vector V as flow field information to PO1 to GPO4
It is assumed that V1 to VV4 are required.

In this case, the grid point GPO1 of the object
~ The position of GPO4 is used as the flow field information for the velocity vector V
You may make it change according to the direction or magnitude | size of V1-VV4. Further, the positions of the grid points GPO1 to GPO4 may be changed according to the directions and sizes of VV1 to VV4 of the velocity vector.

Also, the grid points GPO1 to GP of the flow field HF
Even if O4 and each vertex of the object do not match,
The positions of the vertices of the object are velocity vectors VV1-V
You may make it change with the ratio of the direction of V4. Alternatively, the position of the vertices of the object may be calculated as
It may be changed according to the ratio of the magnitudes of VV4 to VV4.

As a result, according to the fluid simulation, the object itself on which the flow field HF (or the virtual field affected by the flow field) is mapped can be deformed, and the deformation of the object which has never existed is possible. Images can be generated. In addition, it is possible to generate a deformed image of an object that reflects the influence of external factors that occur interactively in real time.

FIGS. 14A and 14B are for explaining the case where the particles generated from the surface of the object on which the flow field HF is mapped in this embodiment are changed based on the information of the flow field HF. The figure is shown.

The flow field HF is mapped on the surface of the object, and as shown in FIG.
In the GPO4, velocity vectors VV1 to VV are used as flow field information.
It is assumed that V4 is required.

For example, the position of the particle PT generated in the flow field HF may be changed according to the velocity vectors VV1 to VV4 of the lattice points PO1 to GPO4. Further, information associated with the particle PT, such as color information or transparency information of the particle PT (for example, life, color information, transparency information), is assigned to each grid point P.
You may make it change according to the velocity vector VV1-VV4 of O1-PO4.

As a result, it is possible to generate particles whose position and state change corresponding to the fluid simulation from the object surface, and it is possible to more realistically express a phenomenon such as dusting or dusting.

Here, the case of mapping a flow field has been described, but the same applies to the case of mapping a virtual field affected by the flow field.

2.5 Variable Control of Flow Field In this embodiment, the flow field obtained by the fluid simulation is the size, the number of divisions performed in a grid pattern,
At least one of the set position, the set number, and the shape (field or grid shape) can be changed. Then, an image in which the fluid motion is reflected is generated in the primitive (including the particle primitive that constitutes the particle system) (in a broad sense, another primitive) at a position where the changed field is reflected.

The flow field may be two-dimensional or three-dimensional, but in the case of two-dimensional flow, the processing load can be reduced by that amount as described above.

FIG. 15 is a diagram for explaining variable control of the flow field.

The case of applying a two-dimensional flow field to a two-dimensional object will be described below, but the same applies to the case of applying a two-dimensional or three-dimensional flow field to a two-dimensional or three-dimensional object.

Here, the flow field obtained by the fluid simulation using the above Navier-Stokes equation is
Consider a case where an image reflected on the object WOBJX is generated.

The object W is placed at a position that reflects the flow field.
When the OBJX is arranged, it is associated with the positions of the constituent points or the control points of the object OBJX, the information associated with the constituent points (color information, transparency information, etc.) and the control points based on the information of each grid point of the flow field. The information (weighting etc.) that is given changes. This allows the object WOBJX
Will generate an image according to the size of the flow field or the number of divisions.

For example, as shown in FIG. 15, the object OBJX has a flow field HFX1 different in size or the number of divisions.
When the positions of the constituent points of each object are changed based on the flow field information (eg velocity vector) of each lattice point of HFX3 to HFX3, the objects OBJX1 to OBJX3
It transforms like.

[0232] Here, the flow field HFX1 and the flow field HFX2
Have the same number of divisions but different sizes. Also, the flow field H
The FX1 and the flow field HFX3 have the same size and different division numbers.

When the flow field HFX2 is set, the number of divisions is the same as in the case where the flow field HFX1 is set, so the accuracy of expressing the flow field is reduced. However, in this case, the state of the flow field can be expressed in an area wider than the flow field HFX1 without increasing the processing load of the fluid simulation.

On the other hand, when setting the flow field HFX3,
Compared to the case where the flow field HFX1 is set, the number of divisions is large, so the processing load of the fluid simulation becomes heavy. However, in this case, the flow field HFX1
Since the state of the flow field can be expressed more accurately than that, it becomes possible to generate a more realistic image.

As described above, by changing the size of the flow field or the number of divisions of the object in consideration of the processing load and the realism of expression, the image generation based on the information of the flow field obtained by the fluid simulation. The processing can be optimized.

In the present embodiment, the size or the number of divisions of the flow field is not limited, and the size of the flow field, the number of divisions of the flow field, the position to set the flow field, the number to be set and the shape of the flow field. At least 1 (including grid shape)
Similarly, it is possible to optimize the processing load and the highly accurate image generation.

2.5.1 Flow Field Setting Changed According to Occurrence of Event In this embodiment, the occurrence of a given event triggers the size of the flow field, the number of divisions of the flow field, and the flow field. At least one of the position to be set, the number to be set, and the shape of the flow field (including the shape of the grid) can be changed.

In the following, the case where the number of divisions of the flow field is changed triggered by the occurrence of a given event will be described.
Here, the given event refers to an event that occurs in association with an object, and is not limited to the type of event. As such an event, for example, there is a hit check processing start event when another object approaches the object that refers to the state of the flow field.

Therefore, for example, when an object image always reflecting the flow field is generated, when the expression is not so realistic, the processing load is prioritized and the flow field with a coarse division number is set. When an event that requires realistic expression occurs, the flow field with a finer number of divisions is set at the cost of an increase in processing load, so that movement or changes in state can be made more realistic and efficient. It is possible to perform an image generation process to be reflected on.

FIG. 16 is a diagram for explaining the setting of the flow field triggered by the occurrence of the event in this embodiment.

Here, a case will be described in which the spread of the flame when the ball is thrown into the flame is represented by a particle system based on the information of the two-dimensional flow field obtained by the fluid simulation.

As for an image of a burning flame, for example, as shown in FIG. 5, according to flow field information obtained by fluid simulation in which an upward velocity vector corresponding to the center of the flame of a bonfire is given as an external factor, particles ( The position of the particle primitive) and the information associated with the particle (for example, lifetime, color information, transparency information, temperature information) are changed. A plate polygon on which a texture representing a flame is mapped is arranged at the position of the particle. For example, a particle maps a texture that shows how it fires with a given color, provided that the temperature information satisfies a given firing condition, and the color of the flame changes with life and eventually smoke, soot, etc. It can be expressed as changing. This temperature information, life, etc. are changed according to the flow field information. Also,
The texture may be changed according to the distance from the center of the flame, the life, and the like.

At this time, the burning of the flame is represented by a texture, and since it is not necessary to faithfully reproduce the influence of the flow field for the change in the position and the state, as shown in FIG. 16, the number of divisions of the flow field HF4 is divided. By coarsely setting, it is possible to allocate an extra processing load to other processing.

Here, the flow field HF4 is set, and the ball object B is placed in the flame represented by the particles whose position changes with reference to the state of the flow field HF4.
It is assumed that the OBJ is thrown.

In this embodiment, the number of divisions of the flow field HF4 is increased to the set position of the flow field HF4, triggered by an event that occurs on condition that the ball object BOBJ approaches the particle expressing the flame. The flow field HF4 'is newly set. And this flow field HF4
The hit check process between the area of the particle and the ball object BOBJ is performed by using ‘. That is,
The start of the hit check process is an event, and the flow field HF4 'with a small number of divisions is set so that the grid points corresponding to the hit positions can be accurately obtained.

Further, in this embodiment, the flow field with the number of divisions changed as described above can be set at the position associated with the detected event. Here, the position associated with the detected event refers to a position determined corresponding to each detected event, and includes, for example, a position where an event factor occurs.

In the above example, the ball object BOB
When the start event of the hit check process occurs due to J approaching the area of the particle (invading within the given distance), the number of divisions is set to the position where the particle is arranged as the position associated with this start event. A fine flow field is set.

Thus, the ball object BOBJ
Position where the particle entered the particle area (hit position)
Therefore, external factors can be accurately reflected in the field. In this case, it is possible to more realistically represent how the surrounding flame spreads when the ball object passes through the flame.

Although only the number of divisions of the flow field is changed here, the size of the flow field may be changed. For example, the ball object BOB
When J expresses the situation of passing through the flame, only that part is set as the flow field, and in other cases, the flow field is set for the entire flame including smoke that rises. While realizing the expression, it is possible to generate an image that pursues the unprecedented realism of the situation of passing through the flame.

As described above, by appropriately changing the size of the flow field with the occurrence of a given event, the processing load of the fluid simulation is not increased.
It becomes possible to generate a real image that reflects external factors that occur interactively in real time.

Although the case where the size of the flow field is changed has been described here, the same is true when the size of the virtual field affected by the flow field is changed.

2.5.2 Setting of flow field changed according to processing load In this embodiment, the size of flow field is changed according to processing load,
At least one of the number of divisions of the flow field, the position at which the flow field is set, the number to be set, and the shape of the flow field (including the shape of the grid) can be changed.

The processing load can be expressed by, for example, integrating the weighted numerical values for each processing performed by the processing unit 100. As a result, it is possible to determine whether the processing load is high or low by determining whether or not the processing load is equal to or higher than a given threshold.

Therefore, for example, when it is determined that the processing load is high, the size of the flow field is made small or the number of divisions is roughly set to reduce the processing load at the expense of the realism of the expression. be able to. On the other hand, when it is determined that the processing load is low, the size of the flow field may be increased or the number of divisions may be set finely to more realistically represent the movement or the change in the state.

Although the case where the size of the flow field is changed has been described here, the same applies to the case where the size of the virtual field affected by the flow field is changed.

2.5.3 Setting one flow field at a plurality of positions In this embodiment, one flow field can be set at a plurality of positions in the object space. That is, it is possible to apply field information that reflects the influence of external factors interactively generated by fluid simulation in one flow field to fields set at a plurality of positions in the object space.

FIG. 17 is a diagram for explaining a case where one flow field in this embodiment is set at a plurality of positions.

The two-dimensional one flow field HF6 is located at a plurality of positions in the object space.
-2, ..., HF6-M is set.

In this case, the information of each grid point of one flow field HF6 updated by the fluid simulation is the flow field HF set at a plurality of positions in the object space.
6-1, HF6-2, ..., Used as field information of HF6-M.

Therefore, the one flow field HF6 is converted into the flow fields HF6-1, HF6-2, ..., HF6− at each position by the fluid simulation in the one flow field HF6.
The state of M can be reflected in each object arranged at a position where the state is referred to.

As a result, an unprecedented realistic and complicated expression can be realized with a smaller processing load.

Here, the case where the size of the flow field is changed has been described, but the same applies to the case where the size of the virtual field affected by the flow field is changed.

2.5.4 Place of Application of External Factor In this way, by applying an external force (external factor) to the flow field in this embodiment to reflect the fluid motion and update the flow field, the output corresponding to the external force is output. Can be reflected at any position in the flow field. That is, it means that the position where the external factor (including an event) given to the flow field is generated and the position where the flow field is set can be different.

This makes it possible to give an effect based on the flow field so that the position where the external factor is applied to the flow field differs from the position where the result of the flow field is applied.

FIG. 18 is a diagram for explaining the relationship between the position where the external factor is generated and the position where the result is applied in this embodiment.

Consider a case where the airplane object FOBJ passes over the two-dimensional flow field HF7 set on the water surface in the object space.

An initial value of the velocity vector is set at each grid point of the flow field HF7. For example, a velocity vector corresponding to a situation where the water surface is calm without wind is set.

At this time, in the present embodiment, the airplane object FOBJ moves in the flow field HF in the traveling direction DIR.
The velocity vector EFV7 as an extrinsic factor is given to a given grid in the flow field HF7 on the condition that the vehicle has passed over 7 above.

That is, the passing position of the airplane object FOBJ as the generation position of the external factor given to the flow field is set to a position different from the position where the flow field is reflected, and the velocity vector of the external factor as the position to which the result of the flow field is applied. EFV7
Is spatially separated from the exogenous position. In FIG. 18, the starting point of the velocity vector EFV7 given as an external factor is shown as being shifted from the grid point.

Therefore, the velocity vector EF is obtained by performing a fluid simulation in the flow field HF7.
Field information is updated to reflect V7. As a result, the information about the field near the grid point to which the velocity vector EFV7 is given changes significantly, and an image can be generated such that the water column WC stands on the water surface, for example. This makes it possible to more realistically represent the water column standing on the water surface when the airplane object FOBJ passes through the water surface.

Although the flow field HF7 has been described as being two-dimensional here, the flow field HF7 may be three-dimensional. When the flow field HF7 is three-dimensional, by reflecting the external factors corresponding to the flow of air due to the passage of the airplane object FOBJ on each grid point of the flow field HF7, the information of the grid point on the water surface is finally changed, Based on this, it is possible to generate an image in which the water column WC stands up.

2.5.5 Detailed Example of Variable Processing of Flow Field Next, a detailed example of the processing of this embodiment in the case of variably controlling the above-mentioned flow field will be described.

FIG. 19 shows an example of processing for setting a flow field in accordance with the occurrence of an event in this embodiment.

First, the process monitoring unit 125 of the processing unit 100 monitors the occurrence of a given event (step S).
10).

[0275] Then, when the process monitoring unit 125 detects the occurrence of a given event, the position setter 115 associates the position with the given event (position determined corresponding to the generated event). For example, a flow field with a changed size or the number of divisions is set at the event occurrence position (step S11).

Next, the simulation operation section 110 performs the fluid simulation as described above to obtain the flow field information of each grid point of the flow field at the next moment (frame) (step S12).

The processing section 100 obtains the flow field information of each grid point and updates the flow field (step S13).

Subsequently, the primitive processing unit 120 positions the constituent points of the object (primitive) at the position where the updated state of the flow field is referred to, color information and transparency information set at each constituent point, and the like. The flow field is applied to the object by changing, for example, using the field information (step S14).

Next, the object whose position or state has changed is generated as an object image viewed from a given viewpoint in the object space, and is output to the display unit or the like (step S15).

Finally, when a given end condition is satisfied (step S16: Y), a series of processes is ended (end), but when the end condition is not satisfied (step S1).
6: N), returning to step S10, the event is monitored again.

By performing the above, a fluid simulation operation can be performed using a flow field of an appropriate size or the number of divisions according to the event occurrence state. Therefore, as shown in FIG. It is possible to achieve both the realism of an image and the efficiency of processing.

FIG. 20 shows an example of processing for setting the flow field according to the processing load in this embodiment.

First, the processing monitoring section 125 of the processing section 100 monitors the processing load (step S20). The process monitoring unit 125 determines the high or low of the process load by, for example, summing and expressing the numerical values obtained by weighting the load for each process performed by the process unit 100 and determining whether or not the value is equal to or more than a given threshold. You can

Then, when the processing monitoring unit 125 determines that the value is equal to or larger than the given threshold value (step S21:
Y), the field setting unit 115 sets the flow field whose size or the number of divisions is changed according to the processing load (step S22).

When it is determined in step S21 that the processing load is smaller than the given threshold value by the processing monitoring unit 125 (step S21: N), or the flow field whose size or the like has been changed is set in step S22. The simulation calculation unit 110 performs the fluid simulation as described above to obtain the flow field information of each grid point of the flow field at the next moment (frame) (step S23).

The processing section 100 obtains the flow field information of each grid point and updates the flow field (step S24).

Subsequently, the primitive processing unit 120, the position of the constituent point of the object (primitive) at the position where the updated state of the flow field is referred to, the color information and the transparency information set at each constituent point, etc. Is applied to the object by changing, for example, using the field information (step S25).

Next, the object whose position or state has changed is generated as an object image viewed from a given viewpoint in the object space, and is output to the display unit or the like (step S26).

Finally, when a given end condition is satisfied (step S27: Y), a series of processes is ended (end), but when the end condition is not satisfied (step S2).
7: N), returning to step S20, the processing load is monitored again.

By doing so, the fluid simulation calculation can be performed using the flow field of an appropriate size or the number of divisions according to the processing load, so that the real-time processing can be performed in a realistic range. Images can be generated.

FIG. 21 shows an example of the processing for setting one flow field at a plurality of positions in the object space in this embodiment.

First, the field setting unit 115 of the processing unit 100 sets one flow field at a plurality of positions in the object space (step S40).

Subsequently, the processing section 100 carries out step S40.
An external input is received for the flow field set in step 1 or the flow field set at each position in the object space (step S41). Here, as external input, flow field information corresponding to external force is accepted. When the flow field information is a velocity vector, the velocity vector EFV having the magnitude and direction corresponding to the external force becomes an external input.

Then, the simulation operation unit 110 performs the fluid simulation as described above in one flow field applied to a plurality of positions in the object space, and each grid point of the flow field at the next moment (frame). The flow field information of (step S42).

The processing section 100 obtains the flow field information of each grid point of the one flow field obtained by the simulation, and updates the flow field (step S43).

Subsequently, the primitive processing unit 120 sets the position of the constituent point of the object (primitive) at the position set at each position and referred to the state of the flow field updated in step S43, and the position of each constituent point. The flow field is applied to the object by changing the set color information, transparency information, and the like using the field information (step S44).

Next, the object whose position or state has changed is generated as an object image viewed from a given viewpoint in the object space, and is output to the display unit or the like (step S45).

Finally, when a given end condition is satisfied (step S46: Y), a series of processes is ended (end), but when the end condition is not satisfied (step S4).
6: N), and returns to step S41 to accept the external input again.

As described above, as shown in FIG. 17, it is possible to realize a change in the position of various objects, color information, and the like, which changes according to a fluid simulation that has never existed before, with a smaller processing load. .

Although the variable process of the flow field has been described, the variable process of the virtual field affected by the flow field can be similarly realized.

2.6 Inheritance of Information to the Outside of the Field In this embodiment, the processing load of the fluid simulation is reduced by setting the size of the above-mentioned two-dimensional flow field to a finite size. More specifically, among the primitives placed in the object space, the flow field is reflected in the primitive located in the field (flow field or virtual field affected by the flow field) set in the object space. Let Furthermore, in the present embodiment, the field is reflected also in the primitive located outside the flow field set in the object space, thereby reducing the processing load without increasing the size of the flow field of the fluid simulation target. ,
It enables real-time processing of fluid simulation.

This point will be described below by taking particles as an example.

Regarding the particles (particle primitives) that refer to the field state, by handling the particles inside and outside the flow field as follows,
It is possible to reduce the processing load and prevent changes in position and state (information related to particles such as lifetime, color, and transparency) from becoming unnatural.

That is, for the particles in the field set in the object space, the position and state of the particles are changed based on the field information or the information influenced by the field. On the other hand, with respect to particles that go out of the flow field set in the object space, according to the information of the field at the time of going out of the field or the information affected by the field (for example, velocity vector), the position and Change the state.

In this case, for the particles inside and outside the flow field, the life calculation is performed according to the generation time from the generation point, and whether the information of the flow field is used for the change of the position or the state is determined. different.

22 (A) and 22 (B) are schematic views for explaining particles that have flowed out of the flow field HF.

As described above, the particle PT₀Is
Life according to the generation time from a given particle generation point
Life calculation is performed, but particles in the flow field HF
PT ₀Position and state change based on the flow field information
It And the flow field information at the time of going out of the flow field HF
Particle PT determined based on₀Information (eg speed
Vector FV₀) Take over. Therefore, the flow field HF
For example, without reference to the flow field information outside the
Cutle FV₀According to particles PT₀The position of
Let At this time, the particles PT₀When the life of
The particles PT₀Extinguish.

Alternatively, for example, in the case of changing the position or state of the particle PT ₀ by referring to the flow field information of the nearest lattice point of the flow field HF, as shown in FIG. The particle PT _{0 that} has come out of the flow field HF inherits the information (for example, the velocity vector FV ₀ ) of the particle PT ₀ that is determined based on the flow field information at the time of going out of the flow field HF, and is the closest to the outside of the flow field HF. Velocity vector FV obtained by referencing only the flow field information of grid point GP _M
The position or information at the next moment (frame) may be determined by ₀ '. In addition, the nearest grid point GP _M-1 ,
The position or state may be determined by the velocity vector FV ₀ ′ obtained by referring to the ratio of the flow field information at three points GP _M and GP _{M + 1} .

FIG. 23 shows an example of an object image of particles that have left the flow field HF.

For example, when expressing a flame of a bonfire, the particles PT that have left the flow field HF move according to the velocity vector at the time of leaving the flow field HF. At this time, the sprite polygons arranged on the particles PT are arranged so that polygons representing black smoke are mapped, and disappear when the life ends.

By doing so, in the flow field obtained by the fluid simulation, the position and state of the particles can be changed based on the flow field information obtained for each grid point of the flow field, and outside the flow field. By taking over the information in the flow field, the position and state of the particles can be changed as they are. Therefore, it is possible to reduce the size of the flow field and reduce the processing load of real-time processing of image generation that represents a natural phenomenon due to particles expressed based on the flow field.

Although the information about the flow field is reflected here, the same applies to the case where the information affected by the flow field is reflected.

2.6.1 Processing Example of Handing Over Flow Field Information FIG. 24 shows an example of processing for changing the position and state of particles.

First, the primitive processing unit 120 initializes information associated with the particle primitive, such as the life of the particle (particle primitive) and the number of particles generated (step S90).

Next, particles are generated from a given generation point (step S91). When expressing the flame of a bonfire, the center of the flame of the bonfire can be set as the particle generation position.

When the particles are in the flow field HF set in the object space (step S92:
Y), the flow field information is given to the particles, and the position and state of the particles are updated (step S93). More specifically, the velocity vector, color, and transparency of particles are updated based on the flow field information of each grid point.

When the particles are outside the flow field HF (step S92: N), the particles are in the flow field H.
The position and state of the particles are updated using the flow field information at the time of going out of F (step S94). More specifically, when the particles go out of the flow field HF, without referring to the flow field information of the flow field HF, only the flow field information at the time when the particles go out of the flow field HF, For example, the velocity vector, color, and transparency of particles are updated.

Incidentally, here, the position and state of the particles that have gone out of the flow field HF are supposed to be updated without referring to the information of the flow field. For example, FIG.
As shown in, the flow field information of the nearest grid point of the flow field HF may be referred to and the position and state thereof may be updated, which is appropriately selected according to what is to be expressed. .

The life of the particles whose position and state have been updated in step S93 or step S94 is determined and the life is updated (step S9).
5).

When it is determined that the life is exhausted (step S96: Y), the process of extinguishing the particles is performed, and when it is determined that the life is not exhausted (step S96).
96: N), returning to step S92, the position and state of the particles are updated again.

By the above, in the flow field obtained by the fluid simulation, the position and state of the particles can be changed based on the flow field information obtained for each grid point of the flow field. Outside the flow field, the position and state of the particles can be changed without changing the information in the flow field. Therefore, as shown in FIG. 23, it is possible to further reduce the processing load of the real-time processing of image generation that represents a natural phenomenon due to particles expressed based on the flow field.

Regarding the particles described above,
Although the case of applying the flow field has been described, the present invention is not limited to this, and the same applies to the case of applying a virtual field affected by the flow field.

2.7 Application Example of this Embodiment With regard to the flow field in this embodiment as described above, for example, an effect is set by following a moving object in the object space and interactively reflecting external factors. It can give an effect.

FIG. 22 is a diagram for explaining the flow field set following the moving object in this embodiment.

Here, the car object COBJM as a moving object is followed to follow the car object CO
The flow field HFM or a virtual field influenced by the flow field is set on the ground behind the rear wheel of the BJM. More specifically, the two-dimensional flow field HFM or the virtual field affected by the flow field is mapped on the surface of the ground object on the rear side of the moving object.

Consider a case in which when the car object COBJM moves forward, a situation in which dust, dirt, and the like are soaring behind the car object COBJM due to movement of the vehicle body, rotation of the tires, and the like.

In this case, in the flow field HFM, the field information is updated by reflecting the external factors such as the moving direction and the moving speed of the vehicle body by the fluid simulation, and the speed vector of the dust object SOBJ is obtained, for example.

At this time, for the two-dimensional XY plane, the position and state of the dust object SOBJ are changed by using the field information obtained by the fluid simulation, and a separate calculation formula (for example, for the height direction is used). , Free fall calculation formula that takes gravity into account)
The BJ can be set to slowly drop to the ground.

Therefore, for example, the position or color information of the dust object SOBJ or the like can be changed based on the field information of the flow field HFM, and the dust and fallen leaves soaring due to the running wind of the car, which could not be expressed up to now. The image to be represented can be generated in real time.

In this case, the car object COBJM is always
The flow field HFM ′ in which the size of the flow field to be set is changed according to the position of the car object COBJM may be set so that the flow field is set to the rear side of.

As a result, the moving car object CO
It is possible to realize generation of an effect image such as dust according to the moving direction and moving speed of the BJM.

The flow field can be changed according to the nature of the ground on which the car object COBJM runs (the nature of the road such as an asphalt road or a gravel road), or the flow field can be changed according to the shape of the ground (the unevenness of the road). Can also be set.

As described above, according to the present embodiment, the expression of monotonous dust or the like is avoided, and the dust or the like generated behind the moving object that reflects the way of moving the moving object or the nature of the ground is reflected. An image to be expressed can be generated in real time.

FIG. 26 shows an example of processing for setting a flow field following a moving object in this embodiment.

First, the flow field is set at the position associated with the moving object (step S100). For example, when the moving object is a car object, the flow field is set on the ground behind the rear wheel of the car object as a position associated with the car object.

Subsequently, the processing section 100 carries out step S10.
External input for the flow field set in 0 is accepted (step S101). Here, as external input, flow field information corresponding to external force is accepted. When the flow field information is a velocity vector, the velocity vector EFV having the magnitude and direction corresponding to the external force becomes an external input. For example, when the moving object is a car object, a velocity vector corresponding to the traveling wind of the car is accepted as an external input.

Then, the simulation operation section 110 performs the fluid simulation as described above,
Flow field information at each grid point of the flow field at the next moment (frame) is obtained (step S102).

The processing section 100 updates the flow field by using the flow field information of each grid point, for example, to obtain the temperature distribution and the concentration change (step S103).

Subsequently, the primitive processing unit 120 obtains the positions of the constituent points of the object (primitive) at the position where the updated flow field is reflected, the color information and the transparency information set for each constituent point, and the like. The flow field is applied to the object by changing it using the field information (step S104). Therefore, for example, when the moving object is a car object, it is possible to change the position and color information of each object that expresses fallen leaves, dust and the like rising from the ground due to the running wind of the car according to the fluid simulation.

Next, the object whose position or state has changed is generated as an object image viewed from a given viewpoint in the object space, and is output to the display unit or the like (step S105).

Finally, when a given end condition is satisfied (step S106: Y), a series of processes is ended (end), but when the end condition is not satisfied (step S).
106: N), the flow returns to step S100, and the flow field is set again at the corresponding position of the moving object.

As described above, the position of each moving object moving in the object space changes according to the fluid simulation, and the color information and the like of various objects change. Can be provided.

3. Hardware Configuration Next, an example of a hardware configuration capable of realizing the present embodiment will be described with reference to FIG.

The main processor 900 is a CD982
It operates based on a program stored in the (information storage medium), a program transferred via the communication interface 990, a program stored in the ROM 950 (one of the information storage media), game processing, image processing,
Various processing such as sound processing is executed.

The coprocessor 902 assists the processing of the main processor 900, has a product-sum calculator and a divider capable of high-speed parallel calculation, and executes matrix calculation (vector calculation) at high speed. For example, when a physical simulation for moving or moving an object requires a process such as a matrix calculation, a program operating on the main processor 900 instructs (requests) the coprocessor 902 to perform the process. ) Do.

The geometry processor 904 performs geometry processing such as coordinate transformation, perspective transformation, light source calculation, and curved surface generation, has a product-sum calculator and a divider capable of high-speed parallel calculation, and performs matrix calculation (vector Calculation) is executed at high speed. For example, when processing such as coordinate transformation, perspective transformation, and light source calculation is performed, the program running on the main processor 900 instructs the geometry processor 904 to perform the processing.

The data decompression processor 906 performs a decoding process for decompressing the compressed image data and sound data, and a process for accelerating the decoding process of the main processor 900. Accordingly, a moving image compressed by a given image compression method can be displayed on the opening screen, the intermission screen, the ending screen, the game screen, or the like. The image data and sound data to be decoded are stored in the ROM 95.
0, stored in the CD 982, or transferred from outside via the communication interface 990.

The drawing processor 910 is for executing the drawing (rendering) processing of an object composed of primitive surfaces such as polygons and curved surfaces at high speed. When drawing an object, the main processor 900
Uses the function of the DMA controller 970 to pass the object data to the drawing processor 910 and, if necessary, transfer the texture to the texture storage unit 924. Then, the drawing processor 910 draws the object in the frame buffer 922 at high speed while performing hidden surface removal using a Z buffer or the like based on these object data and texture. Also,
The drawing processor 910 can also perform numb u rendering (semi-transparent processing), depth cuing, mip mapping, fog processing, trilinear filtering, anti-aliasing, shading processing, and the like. Then, when the image for one frame is written in the frame buffer 922, the image is displayed on the display 912.

The sound processor 930 incorporates a multi-channel ADPCM sound source, etc., and generates high-quality game sounds such as BGM, sound effects, and sounds. The generated game sound is output from the speaker 932.

Operation data from the game controller 942, save data from the memory card 944, and personal data are transferred via the serial interface 940.

The ROM 950 stores system programs and the like. In the case of the arcade game system, the ROM 950 functions as an information storage medium,
Various programs are stored in 950. A hard disk may be used instead of the ROM 950.

The RAM 960 is used as a work area for various processors.

The DMA controller 970 is a DM between processors and memories (RAM, VRAM, ROM, etc.).
It controls the A transfer.

The CD drive 980 is a CD 982 for storing programs, image data, sound data and the like.
(Information storage medium) is driven to enable access to these programs and data.

The communication interface 990 is an interface for transferring data with the outside via a network. In this case, a communication line (analog telephone line, ISDN), high-speed serial bus, or the like can be considered as the network connected to the communication interface 990. Then, by using the communication line, data transfer via the Internet becomes possible. Further, by using the high-speed serial bus, data transfer with another game system becomes possible.

All the means of the present invention may be executed by hardware only, or may be executed only by a program stored in an information storage medium or a program distributed via a communication interface. Good. Alternatively, it may be executed by both hardware and a program.

When each means of the present invention is executed by both hardware and a program, the information storage medium stores a program for executing each means of the present invention using hardware. Will be. More specifically, the program instructs each processor 902, 904, 906, 910, 930, which is hardware, to perform processing, and passes data if necessary.
Then, each processor 902, 904, 906, 91
0, 930, etc. will execute each means of the present invention based on the instruction and the passed data.

FIG. 28A shows an example in which this embodiment is applied to an arcade game system. The player enjoys the game by operating the lever 1102, the buttons 1104, etc. while watching the game image displayed on the display 1100. Various processors, various memories, etc. are mounted on the built-in system board (circuit board) 1106. Information (program or data) for executing each unit of the present invention is stored in the memory 1108 which is an information storage medium on the system board 1106. Hereinafter, this information will be referred to as stored information.

FIG. 28B shows an example in which this embodiment is applied to a home game system. While watching the game image displayed on the display 1200, the player operates the game controllers 1202 and 1204 to enjoy the game. In this case, the above-mentioned stored information is stored in the CD 1206 or the memory cards 1208, 1209, which is an information storage medium that can be detachably attached to the main body system.

In FIG. 28C, the host device 1300 and
This host device 1300 and network 1302 (LA
A terminal 130 connected via a small network such as N or a wide area network such as the Internet)
An example in which the present embodiment is applied to a system including 4-1 to 1304-n will be described. In this case, the stored information is, for example, a magnetic disk device that can be controlled by the host device 1300,
It is stored in an information storage medium 1306 such as a magnetic tape device or a memory. When the terminals 1304-1 to 1304-n are capable of standalone generation of game images and game sounds, the host device 1300 sends game images,
A game program or the like for generating a game sound is provided on the terminal 1
It is delivered to 304-1 to 1304-n. On the other hand, when it cannot be generated standalone, the host device 1300 generates a game image and a game sound, and the terminal device 1304-1 ...
It will be transmitted to 1304-n and output at the terminal.

In the case of the configuration of FIG. 28C, the respective means of the present invention may be distributed and executed by the host device (server) and the terminal. In addition, the above stored information for executing each means of the present invention is stored in the host device (server).
The information storage medium and the information storage medium of the terminal may be distributed and stored.

The terminal connected to the network may be a home-use game system or an arcade game system. When the arcade game system is connected to a network, a portable information storage device is capable of exchanging information with the arcade game system and also with the home game system. (Memory card, portable game device) is preferably used.

The present invention is not limited to that described in the above embodiment, and various modifications can be made.

For example, in the present embodiment, the fluid simulation calculation has been mainly described as an example, but the simulation calculation of the present invention is not limited to the fluid simulation calculation. Further, the present invention is not limited to the flow field, and the present invention can be applied to fields related to various physical quantities.

The method of simulation calculation is also shown in FIG.
The method is not limited to the method described in FIG. 6, and the simulation calculation may be performed based on an equation different from the Navier-Stokes equation.

Further, in the present embodiment, the description has been given by taking the lattice point as an example of the point belonging to the vector field, but it is not limited to this. The points may not be arranged in a grid pattern.

Further, in the present embodiment, a flow field (flow field information) can be applied to a virtual field affected by the flow field by the same method (information affected by the flow field).
Can be applied. In addition, a virtual field that is influenced by the flow field (information that is influenced by the flow field) can be applied to the flow field (information of the flow field) by a similar method.

Further, in the invention according to the dependent claims of the present invention, it is possible to omit some of the constituent elements of the dependent claims. Further, a main part of the invention according to one independent claim of the present invention can be made dependent on another independent claim.

In addition, the present invention is applicable to various games (fighting games,
It can be applied to shooting games, robot battle games, sports games, competition games, role playing games, music playing games, dance games, etc.).

The present invention is also applicable to various image generation systems (games) such as an arcade game system, a home game system, a large attraction system in which many players participate, a simulator, a multimedia terminal, and a system board for generating game images. System).

[Brief description of drawings]

FIG. 1 is an example of a functional block diagram of an image generation system of this embodiment.

FIG. 2 is a schematic diagram for explaining a procedure when performing a fluid simulation.

FIG. 3 is a flowchart for explaining a procedure when performing a fluid simulation.

4 (A), (B), and (C) are diagrams schematically showing changes in the state of the field when a velocity vector corresponding to an external force is applied to the flow field.

FIG. 5 is a diagram for explaining boundary conditions.

6A, 6B, and 6C are diagrams for explaining a cavity problem as a specific calculation example.

FIG. 7 is an explanatory diagram schematically showing the relationship between a two-dimensional flow field and a three-dimensional object space in this embodiment.

FIG. 8 is a diagram showing an example of an object image when a two-dimensional flow field is applied to an expression of a bonfire flame.

FIG. 9 is an explanatory diagram schematically showing a field mapped to an object in the present embodiment.

FIG. 10 is a diagram for explaining UV mapping of a two-dimensional flow field performed on an object in the present embodiment.

FIG. 11 is a diagram showing an example of an image of an object space in which sprite polygons are arranged in the present embodiment.

12A and 12B are explanatory diagrams for explaining a case where a normal vector of an object onto which a flow field is mapped according to the present embodiment is changed based on flow field information. is there.

13A and 13B are explanatory diagrams for explaining a case where the position of the vertex of the object onto which the flow field is mapped in the present embodiment is changed based on the flow field information. is there.

14A and 14B are explanatory views for explaining a case where particles generated from the surface of an object on which a flow field is mapped according to the present embodiment are changed based on flow field information. It is a figure.

FIG. 15 is an explanatory diagram for explaining variable control of a flow field in the present embodiment.

FIG. 16 is an explanatory diagram for describing flow field setting triggered by the occurrence of an event in the present embodiment.

FIG. 17 is an explanatory diagram for describing a case where one flow field is set at a plurality of positions in the present embodiment.

FIG. 18 is an explanatory diagram for describing a relationship between an extrinsic occurrence position and an application position of a result in the present embodiment.

FIG. 19 is a flowchart showing an example of processing for setting a flow field according to the occurrence of an event in the present embodiment.

FIG. 20 is a flowchart showing an example of processing for setting a flow field according to processing load in the present embodiment.

FIG. 21 is a flowchart showing an example of processing when one flow field is set at a plurality of positions in the object space in the present embodiment.

22 (A) and 22 (B) are explanatory views schematically showing particles that have come out of the flow field.

FIG. 23 is a diagram showing an example of an object image by particles that have left the flow field in the present embodiment.

FIG. 24 is a flowchart showing an example of processing for changing the position and state of particles in the present embodiment.

FIG. 25 is a flowchart showing an example of a process of setting a flow field following a moving object in the present embodiment.

FIG. 26 is a flowchart showing an example of processing for setting a flow field following a moving object in the present embodiment.

FIG. 27 is a diagram showing an example of a hardware configuration capable of realizing the present embodiment.

28 (A), (B), and (C) are diagrams showing examples of various types of systems to which the present embodiment is applied.

[Explanation of symbols]

100 processing unit 110 simulation calculation unit 115 field setting unit 120 primitive processing unit 125 processing monitoring unit 140 image generation unit 150 sound generation unit 160 operation unit 170 storage unit 180 information storage medium 190 display unit 192 sound output unit 194 portable information storage device 196 Communication unit HFX1 to HFX3 Flow field WOBJX, WOBJX1 to WOBJX3 object

Continued front page    F-term (reference) 2C001 AA03 AA06 AA11 AA14 AA16                       BA02 BA04 BA05 BA06 BA07                       BB01 BB02 BB03 BB04 BC02                       BC03 BC04 BC05 BC06 CA02                       CB01 CB02 CB04 CB06 CB08                       CC01 CC08 DA04                 5B050 BA08 BA11 EA24

Claims (17)

[Claims] 1. An image generation system for generating an image, wherein at least a size, a division number, a setting position, a setting number, and a shape of a field formed based on a physical quantity at each point obtained by dividing a simulation space. A field setting means for changing and setting one, and obtaining a change in the physical quantity by a simulation calculation,
From the given viewpoint of the object space in which the primitive is placed, a simulation calculation means for obtaining the field, a means for changing the position of the primitive or information associated with the primitive by using the physical quantity at each point of the field, An image generation system comprising: a means for generating a viewed image. 2. The image generation system according to claim 1, further comprising means for changing a position of the particle or information associated with the particle by using a physical quantity at each point of the field. 3. The apparatus according to claim 1 or 2, further comprising: a unit for monitoring a processing load, wherein the field setting unit includes a size, a division number, a setting position, a setting number and a shape of the field according to the processing load. An image generation system characterized by changing and setting at least one. 4. The device according to claim 1, further comprising means for detecting a given event, wherein the field setting means is configured to detect the size of the field based on the detection result of the event.
At least one of the number of divisions, setting position, setting number, and shape
An image generation system characterized by changing and setting one. 5. The image generation system according to claim 4, wherein the field or a virtual field influenced by the field is set at a position associated with the event. 6. The image generation system according to claim 4, wherein a position where the event occurs and a position where the field or a virtual field influenced by the field is set are different from each other. 7. The information according to claim 1, wherein the information of one field where the simulation calculation is performed or the information affected by the field is a field set at a plurality of positions in the object space. An image generation system characterized by being used as information. 8. The image according to claim 1, wherein the field or the virtual field affected by the field is set at a position that follows a primitive moving in the object space. Generation system. 9. A field setting means for changing and setting at least one of a size, a division number, a setting position, a setting number and a shape with respect to a field formed based on a physical quantity at each point obtained by dividing the simulation space. And obtain the change in the physical quantity by simulation calculation,
From the given viewpoint of the object space in which the primitive is placed, a simulation calculation unit that obtains the field, a unit that changes the position of the primitive or information associated with the primitive by using the physical quantity at each point of the field, A program that causes a computer to function as a means for generating a viewed image. 10. The program according to claim 9, which causes a computer to function as means for changing the position of a particle or information associated with a particle by using a physical quantity at each point of the field. 11. The computer according to claim 9 or 10, wherein the field setting means causes the size of the field, the number of divisions, the setting position, the number of settings, and the like to function as a means for monitoring the processing load. A program for changing and setting at least one of the shapes. 12. The computer according to any one of claims 9 to 11, wherein the field setting means causes the size of the field, based on a detection result of the event, to cause a computer to function as means for detecting a given event.
At least one of the number of divisions, setting position, setting number, and shape
A program characterized by changing and setting one. 13. The program according to claim 12, wherein the field or a virtual field influenced by the field is set at a position associated with the event. 14. The program according to claim 12, wherein a position at which the event occurs and a position at which the field or a virtual field influenced by the field is set are different from each other. 15. The information according to claim 9, wherein the information of one field where the simulation calculation is performed or the information affected by the field is a field set at a plurality of positions in the object space. A program characterized by being used as information. 16. The program according to claim 9, wherein the field or the virtual field affected by the field is set at a position that follows a primitive moving in the object space. . 17. An information storage medium which can be read by a computer and stores the program according to any one of claims 9 to 16.