JP3445568B2 - Water surface image forming method, computer-readable storage medium for realizing the method, and game system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an image suitable for use in expressing a water surface.

[0002]

2. Description of the Related Art With the improvement in image processing capability of computers, video games in recent years are becoming mainstream using three-dimensional realistic images. When forming a three-dimensional image by a computer, generally, an object to be displayed on the game screen is represented as a three-dimensional model composed of a large number of polygons, the model is arranged in a virtual three-dimensional space, and then each polygon is arranged. The game screen is formed by converting the vertex coordinates into two-dimensional coordinates in a predetermined screen coordinate system, and further performing rendering processing such as hidden surface processing and texture mapping.

[0003]

By the way, in image processing applied to a computer such as a home game machine or a personal computer, it is an important issue to realistically represent the water surface. In order to solve such a problem, an attempt has been made to express the movement of the water surface by configuring the water surface with a large number of polygons and to precisely express the reflection of the water surface by performing a complicated light source calculation.
However, these processings impose a heavy burden on the computer, and as a result, it is still impossible to represent a realistic water surface with hardware having low image processing capability.

Therefore, according to the present invention, an image forming method capable of expressing a moving water surface with sufficient quality and requiring a relatively small calculation processing load, a storage medium suitable for realizing the image forming method, and The purpose is to provide a game system.

[0005]

The present invention will be described below. In addition, in order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are added in parentheses, but the present invention is not limited to the illustrated forms.

In the method of forming an image of the water surface according to the present invention, a large number of polygons (2) for constructing the water surface model (1) are used.
And data relating to the coordinates of each vertex of, for a plurality of textures representing the water surface pattern to be mapped to the polygon (3) included in a predetermined range of the water surface model
The storage means (55) storing the data and the vertical coordinate (Y-axis direction) of the coordinates of the vertices of each polygon recorded in the storage means are changed based on the information designating the movement of the water surface. Means (58) and recorded in said storage means
The means for mapping the texture to each polygon while changing the vertical coordinate functions to variables of the vertex correspondence between the predetermined range into coordinates on the texture and the vertices of each polygon included (58) and
The above-described problems are solved by making the computer function .

According to the image forming method of the present invention, a state in which the water surface swells up and down can be expressed by changing the positions of the vertices of each polygon constituting the water surface model in the vertical direction. Moreover, by changing the coordinates on the texture associated with each vertex according to the change in the height of the vertex, the water surface pattern expressed by the texture seems to move in synchronization with the movement of the water surface model,
It is possible to express a high quality water surface. Since the position corresponding to each vertex on the texture is simply changed according to the change in the Y coordinate of the vertex of the polygon, it is not necessary to move the vertex of the polygon intricately, and the load of arithmetic processing associated with image formation is relatively small. You may

In the image forming method of the present invention, various forms can be considered for the relationship between the predetermined range of the water surface model and the texture. For example, the entire water surface model may be set as one predetermined range, and only one texture corresponding to this may be prepared. A plurality of predetermined ranges may be set in the water surface model, and the same or different textures may be prepared for each range. The texture preferably represents a water surface pattern when the water surface is in a static state. The calm state here refers to a state in which an appropriate fluctuation occurs on the water surface due to a natural phenomenon, such as a state in which the water surface of a swimming pool is moderately undulated by wind. The movement of the water surface is caused by an external factor such as a dive, a wave dragged by an object moving on or under water, strong wind, or vibration. In the present invention, the information for specifying these external factors is acquired as the information for specifying the movement of the water surface, thereby changing the vertical coordinates of the vertices of each polygon and responding to the external factors. Express the movement of the water surface.

In the present invention, the correspondence between the change in the coordinates of the vertices of the polygon in the vertical direction and the coordinates on the texture is such that the texture changes depending on whether the vertices of the polygon move upward or downward. It is advisable to set the upper coordinates so that they change in opposite directions on the texture. As a result, the area on the texture to be mapped to each polygon expands and contracts according to the vertical movement of the water surface, and the movement of the water surface pattern is well expressed.

In the present invention, the computer is associated with the change in the vertex coordinates of the polygon (2) in the vertical direction, and the brightness at the vertices of each polygon is such that the upper vertices are bright and the lower vertices are dark. Is preferably changed, and also functions as a means (58) for setting the brightness in each polygon so as to interpolate the brightness of each vertex.

When the brightness is changed in this way, the portion displaced above the water surface is relatively brighter than the original texture, and the portion displaced below is relatively darker than the original texture. It will be expressed, and the movement of the water surface will be expressed in higher quality. The interpolation here means a process of determining the brightness of each pixel inside the polygon based on the brightness of each vertex of the polygon so that the brightness changes smoothly between each vertex.

In the present invention, the polygons forming the water surface model can be triangular or quadrangular. A triangular polygon is desirable for drawing a fine water surface, but a quadrangular polygon is preferable for reducing the processing load by reducing the number of polygons. In particular, the processing can be easily performed by arranging a large number of rectangular polygons in a grid to form a water surface model.

The technical idea of the present invention may be embodied as a storage medium for realizing the above-described image forming method.

That is, the storage medium (55) of the present invention is
Computer, and data relating to a number of the coordinates of each vertex of the polygon (2) for constituting the water surface model (1),
Storage means (5 ) for recording data regarding a texture (3) representing a water surface pattern to be mapped to a plurality of polygons included in a predetermined range of the water surface model.
5) and the memory based on the information designating the movement of the water surface
A means (58) for changing the vertical coordinates among the coordinates of the vertices of each polygon recorded in the means;
The texture is mapped to each polygon while changing the correspondence between the vertices of each polygon included in the recorded predetermined range and the coordinates on the texture by a function having the vertical coordinate of the vertex as a variable. Means (5
8), and is characterized in that a program for functioning as is recorded.

According to the technical idea of the present invention, a computer-readable storage medium (55) having recorded therein information for executing any one of the above-described image forming methods by a computer (53), or any one of the above. It may be embodied as a game system including a game control device (53) configured as a computer for realizing the image forming method.

The water surface of the present invention is not limited to water and includes liquid surfaces formed by various liquids. That is, the present invention can be applied with the front side or the back side of the liquid surface formed at the boundary between various liquids and gas as the water surface.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An example of a method for expressing a water surface according to the present invention will be described with reference to FIGS. 1 and 2. Figure 1 (a)
And (b) show the water surface model 1 and the texture 3 corresponding to it, which are used in the present embodiment, respectively.

The water surface model 1 of FIG. 1 (a) is constructed by arranging rectangular polygons 2 ... 2 in a grid pattern. Polygon 2 has 10 polygons in the X-axis direction and 12 polygons in the Z-axis direction for a total of 120
It is provided individually. However, the number of polygons 2 may be appropriately changed according to the processing capacity of the computer.

On the other hand, one texture 3 shown in FIG. 1B is prepared for each of the above 120 polygons 2. Texture 3 represents a water surface pattern when the water surface is in a static state. The size of the texture 3 is set to be the same as or larger than the size of the water surface model 1. A two-dimensional coordinate system (UV coordinate system) is set for the texture 3.
The U-axis direction of the texture 3 corresponds to the X-axis direction in the water surface model 1, and the V-axis direction corresponds to the Z-axis direction in the water surface model 1. Note that the coordinate system shown in FIG. 1 is set for convenience of description, and the direction of the coordinate axis and the position of the origin may be changed as appropriate according to the circumstances of actual calculation. However, in the present embodiment, the Y-axis direction of the water surface model 1 corresponds to the vertical direction in the game space, and the upper side in the Y-axis direction is the vertically upward direction in the game space. The game space is a virtual three-dimensional space in which objects such as the water surface model 1 are placed.

The water surface model 1 shown in FIG. 1A is when the water surface is in a calm state. In the method of the present invention, the coordinates of the vertices of each polygon 2 forming the water surface model 1 in the Y-axis direction are
The polygon 2 is changed according to the change of the Y coordinate of the vertex of each polygon 2 while changing so as to represent the swell of the water surface.
The correspondence between the apex of and the coordinates on the texture 3 is changed.

FIG. 2A shows a state in which the coordinates of the vertices of one polygon 2 in the Y-axis direction (hereinafter referred to as the Y coordinate) are changed from the stationary state. Here, 4 of polygon 2
One vertex is 0 to 3, and the Y coordinate of each vertex 0 to 3 is py
When defined as [1] to py [3], since the Y coordinate corresponds to the vertical direction of the game space, the Y coordinates of the vertices 0 to 3 of each polygon 2 have the same value when the water surface is in a stationary state. Therefore, py [1] to py in a calm state
[3] Assuming that 0, the Y coordinate takes a positive value proportional to the movement amount when the vertex moves upward, and the negative value proportional to the movement amount when the Y coordinate moves downward. I shall.

FIG. 2B shows the correspondence between the vertices of the polygon 2 and the coordinates on the texture 3. When the water surface is in a static state, positions P0 to P3 on the texture 3 are added to the vertices 0 to 3 of the polygon 2 arranged at specific positions of the water surface model 1.
, P0 to P, respectively.
A rectangular area surrounded by 3 becomes a mapping area 4 for the polygon 2. That is, in this embodiment, 12
Although one texture 3 is attached to 0 polygons 2, the pattern of the corresponding mapping area 4 in the texture 3 is attached individually from the viewpoint of each polygon 2.

In the example of FIG. 2 (b), when the water surface model 1 is in a stationary state, U at corresponding positions P0 to P3 on the texture 3 are obtained.
Regarding coordinates in the −V coordinate system, P0 is (Ua, V
a), P1 is (Ub, Va), P2 is (Ub, Vb),
P3 is given as (Ua, Vb). These coordinates are polygons 2 when it is assumed that the texture 3 is bonded to the water surface model 1 in a static state without being deformed.
The coordinates on the texture 3 correspond to the vertices of. Therefore, the above-mentioned coordinate values Ua, Ub, Va, and Vb are the polygon 2
It takes a different value for each.

When the Y-coordinates of the vertices of the polygon 2 change from the static state, the positions on the texture 3 corresponding to the vertices of each polygon 2 also change accordingly. The coordinates of the changed positions P0 to P3 in the UV coordinate system are (U0, V0) for the position P0 and (U1, V for the position P1.
1), the position P2 is (U2, V2), and the position P3 is (U3, V3), the coordinates are as a function of the Y coordinates py [1] to py [3] of the vertices of the polygon 2 by the following formula. Given.

[0025]

[Equation 1]   U0 = Ua + i · py [0], V0 = Va + j · py [0]   U1 = Ub + i · py [1], V1 = Va + j · py [1]   U2 = Ub + i · py [2], V2 = Vb + j · py [2]   U3 = Ua + i · py [3], V3 = Vb + j · py [3]

Here, i and j are Y of each vertex of the polygon 2.
It is a coefficient that associates the amount of change in coordinates with the amount of change in reference coordinates on the texture 3. The coefficients i and j may be adjusted to optimum values while checking the texture of the water surface expressed by the present invention. Further, as described above, Ua, Ub, Va, V
b is the U and V coordinates on the texture 3 to be associated with the respective vertices 0 to 3 of the polygon 2 in the stationary state.

From the above equation, the vertices 0 to 0 of each polygon 2
3 and the coordinates on the texture 3 to be associated with each vertex (sometimes referred to as reference coordinates) correspond to the Y coordinates of the vertices of the polygon 2 py [1] to py [3].
Change according to. For example, when the vertices of the polygon 2 change in the Y-axis direction as shown by the imaginary line in FIG. 2A, the position on the texture 3 shown in FIG. Move to the top of. The hatched portion surrounded by the quadrangle becomes the mapping area 4 for the polygon 2 after the water surface change shown by the imaginary line in FIG.
That is, in this embodiment, the mapping area 4 on the texture 3 to be attached to each polygon 2 changes according to the change in the Y coordinate of the vertex of the polygon 2. Moreover, as is clear from the above equation, the change is that the coordinates on the texture 3 associated with the vertices of each polygon 2 are the texture when the vertices of each polygon 2 move upward and downward. 3 will change in opposite directions. So to speak, each polygon 2 on texture 3
The mapping area 4 corresponding to is expanded or contracted in the opposite directions in the UV coordinate system according to the vertical movement of the water surface.

By associating the Y coordinates of the vertices of each polygon 2 with the reference coordinates on the texture 3 corresponding to each vertex as described above, the movement of the water surface represented by the water surface model 1 and the texture 3 can be obtained. The movement of the drawn water surface pattern is synchronized, and the moving water surface can be expressed in high quality.

When the texture 3 is formed to have the same size as the water surface model 1, the vertices of the polygon 2 located at the outer peripheral edge of the water surface model 1 may have U depending on the direction of change of the Y coordinate. The corresponding position in the −V coordinate system may deviate from the texture 3 and the texture 3 may not be mapped. In order to prevent such an inconvenience, the Y coordinates of the vertices of the polygons 2 that form the outer peripheral edge of the water surface model 1 may be fixed in a stationary state. Alternatively, the upper and lower limits are limited to the range in which the Y coordinates of the vertices of the polygon 2 change, and even when the Y coordinates of the vertices of the polygon 2 located on the outer peripheral edge of the water surface model 1 are the upper and lower limits, the U-V coordinates. The texture 3 may be larger than the water surface model 1 so that the corresponding position of the system exists in the texture 3.

Further, in this embodiment, in order to further enhance the texture of the water surface, as shown in FIG. 2A, the vertices 0 to 3 of the polygon 2 are set to the luminances L0 to L3, respectively, and the water surface is in a quiet state. When the water surface is moving, the brightnesses L0 to L3 are changed according to the Y coordinates py [1] to py [3] of the vertices of the polygon 2 when the water surface is moving. I was allowed to. This can be expressed by the following formula.

[0031]

## EQU2 ## Ln = Lm + f (py [n])

Here, n is an integer of 0 to 3 representing a vertex, and Lm is a luminance given to each vertex when the user is at rest.
f (py [n]) means that it is a function of the Y coordinate of the vertices 0 to 3 of the polygon 2, and the Y coordinate is 0 (that is, at the time of calmness).
Takes a value of 0, and changes in the bright direction as the Y coordinate increases in the positive direction, and changes in the dark direction as the Y coordinate decreases in the negative direction. As a result, the vertices that have moved to the upper side of the rest position are bright, and the vertices that have moved to the lower side are dark.
The upper limit and the lower limit are set in the range of the brightness Ln obtained by the above formula, and the function f (py [n]) needs to be determined in consideration of the upper limit and the lower limit. Further, after determining the brightness L0 to L3 of the vertices 0 to 3 of the polygon 2, the brightness of each position in the polygon 2 is continuously changed by further interpolating the brightness of each of the vertices 0 to 3 in the present embodiment. Let

By the brightness processing as described above, a complicated light source calculation is performed for a change in light that cannot be obtained by setting a single light source for the water surface model 1 and performing light source calculation. It can be expressed without it, and the texture of the water surface is further improved.

FIG. 3 shows an example of the water surface drawn as described above, and FIG. 4 shows an enlarged view of the central portion of the water surface. In each drawing, in order to show the relationship between the texture and the polygon, the vertices of the polygon are connected by a line, but of course, such a grid-like line is not displayed on the actual screen. In the examples shown in these figures, after a character (not shown) of the game jumps into the approximate center of the water surface, the water surface at the jumped-in position is rising due to the reaction.

FIG. 5 shows an example of a game system for realizing the above-mentioned image forming method. The game system 51 includes an input device 52, a game control device 53,
And a display device 54. The input device 52 has a plurality of operation members operated by the player, and outputs an operation signal corresponding to the operation state of these operation members. As the input device 52, for example, a known device having a hand-held housing provided with a plurality of input members such as buttons and joysticks can be used. The game control device 53 is configured as a computer in which a microprocessor and various peripheral parts necessary for its operation are combined. The game control device 53 executes various calculations and image processing necessary for executing a predetermined game in accordance with the game program recorded in the storage medium 55. The display device 54 receives the video signal from the game control device 53 and displays an image corresponding to the video signal.

The storage medium 55 includes a CD-ROM and a DVD.
Various media such as an optical storage medium such as a ROM, a magneto-optical storage medium such as an MO, a magnetic storage medium such as a floppy disk or a hard disk, and a semiconductor memory such as a flash ROM can be used. In the storage medium 55, in addition to the game program described above, various data necessary for executing the game are recorded. For example, the polygon information in which the coordinates of the vertices of each polygon 2 forming the water surface model 1 are described according to the coordinate system (object coordinate system) related to the water surface model 1 and the information on each pixel forming the texture 3 are UV.
The texture information described by the coordinate system is stored in the storage medium 55.
Recorded in.

The game program and data recorded in the storage medium 55 are read by the game control device 53 via a predetermined reading device 56, and the game control device 53 is read as necessary.
Stored in the memory 60. The memory 60 is a RAM that provides a work area for the game control device 53 and a ROM that stores an OS required for the basic operation of the game control device 3.
Etc.

When the game control device 53 reads the game program from the storage medium 55 and executes it, the game calculation part 57,
An image calculation unit 58 and an image data generation unit 59 are configured. In the game calculation section 57, calculation for specifying the progress status of the game is repeatedly executed according to the operation status of the input device 52. For example, the position and orientation of the character appearing in the game in the game space, the change of the viewpoint according to the operation of the input device 52, and the like are calculated.

The image calculation section 58 performs various calculations necessary to generate a game screen according to the calculation result of the game calculation section 57. This arithmetic processing includes various arithmetic operations for drawing the water surface described above. When the image calculation unit 58 executes the calculation necessary for drawing the game screen, the image data generation unit 59 generates the image data to be output to the display device 54 according to the calculation result.
The image data is generated. The generated image data is output to the display device 54 according to a predetermined synchronization signal. The configuration of the game system 51 as described above is widely adopted in a general arcade game machine, a home-use game machine, a portable game machine, or a personal computer.

FIG. 6 shows the procedure of processing executed by the game control device 53 when forming an image of the water surface.
When the game calculation unit 57 calculates the progress of the game and, as a result, it becomes necessary to give a motion to the water surface, the game calculation unit 57 generates information designating the motion. For example, if a character jumps into the water,
The position at which the user jumped in, the speed at which the user jumped in, and the like are generated as information designating the movement. When this information is generated, the processing of FIG. 6 is started in the image calculation unit 58, and first, the Y coordinate of the apex of each polygon 2 of the water surface model 1 is calculated based on the given information specifying the movement of the water surface. (Step S1). Next, the reference coordinates on the texture 3 corresponding to the vertices of each polygon 2 are calculated based on the calculated Y coordinates (step S2). Based on the calculation result, the texture 3 is mapped to each point of the water surface model to determine the color of each pixel forming the water surface (step S3).

Further, the brightness to be given to the vertices of each polygon 2 is calculated based on the calculation result of step S2, that is, the Y coordinate of the vertices of each polygon 2 (step S4), and then the brightness given to the vertices is interpolated. In this way, the brightness of each pixel in each polygon 2 is calculated (step S
5). This completes the processing of FIG.

When the color and brightness of each pixel forming the water surface are determined by the processing of FIG. 6, the image calculation section 58 further performs various kinds of rendering processing necessary for image formation. The calculation result of the image calculation unit 58 is passed to the image data generation unit 59, where the image data reflecting the calculation result of the game calculation unit 57 is generated, and the image data is output to the display device 54 to display the game screen including the water surface. Is displayed.

The present invention is not limited to the above embodiments and may be implemented in various forms. For example, when a water surface of sufficient quality can be drawn only by changing the corresponding position (reference coordinates) on the texture 3 in correspondence with the change of the Y coordinate of the vertex of the polygon 2, the change in brightness may be omitted. One water surface model may be divided into a plurality of areas, and the same texture may be used for each area. One water surface model may be divided into a plurality of areas, and different textures may be prepared for each area for mapping. The polygons forming the water surface model may be triangular, for example. Although the present invention has been described for the case of forming an image in which the water surface is looked down from above the water, the present invention is also applicable to the case of forming an image in which the water surface is looked up from underwater. The water surface formed by the present invention may be a water surface limited to a narrow range such as a pool, or a wide water surface such as a seawater surface.

[0044]

As described above, according to the image forming method of the present invention, the movement of the water surface is expressed by changing the coordinates in the vertical direction of the vertices of the polygons forming the water surface model, and By changing the reference coordinates on the texture corresponding to the vertices of each polygon according to the change, the water surface pattern drawn by the texture appears to move in synchronism with the movement of the water surface model. Can be expressed. Since the position corresponding to each vertex on the texture is simply changed according to the change of the Y coordinate of the vertex of the polygon, it is not necessary to move the vertex of the polygon in a complicated manner. It can be small. Further, particularly when the brightness of the polygon is changed according to the present invention, it is possible to express the change of the brightness according to the vertical movement of the water surface without setting the light source, so that the complicated light source calculation is unnecessary. At the same time, the water surface can be drawn with higher quality by expressing changes in light that cannot be obtained by a simple light source calculation.

[Brief description of drawings]

FIG. 1 is a diagram showing a water surface model and a texture used in an image forming method of the present invention.

FIG. 2 is a diagram showing a relationship between changes in the vertices of a polygon due to movement of the water surface and changes in reference coordinates on a texture.

FIG. 3 is a diagram showing an example of an image of a water surface formed by the present invention.

FIG. 4 is an enlarged view showing a central portion of the water surface in FIG.

FIG. 5 is a functional block diagram of a game system for realizing the image forming method of the present invention.

6 is a flowchart showing an image forming procedure executed by the game control device of the game system of FIG.

[Explanation of symbols]

1 Water surface model 2 Polygons that compose the water surface 3 Textures mapped to the water surface model 51 game system 52 Input device 53 Game control device 54 display device 55 storage media 56 reader 57 Game operation section 58 Image calculator 59 Image data generator

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G06T 15/70 A63F 13/00 G06T 15/00 300

Claims (8)

(57) [Claims] 1. A number of polys for constructing a water surface model.
De data relating coordinates of each vertex of the polygon, regarding texture representing the water surface pattern to be mapped to a plurality of polygons included in a predetermined range of the water surface model
Storage means in which a chromatography data is recorded, and means for varying the vertical coordinate of the water surface of the vertices of each polygon stored in said storage means based on information specifying the motion coordinates,
While changing the correspondence relationship between the vertices of each polygon included in the predetermined range recorded in the storage means and the coordinates on the texture by a function having the coordinates of the vertices in the vertical direction as a variable, A method of forming an image of a water surface, characterized by causing a computer to function as a means for mapping texture. 2. The image forming method according to claim 1, wherein the texture represents a water surface pattern when the water surface is in a static state. 3. The coordinates on the texture associated with the vertices of each polygon change in opposite directions on the texture when the vertices of the polygon move upward and downward. The method for forming an image according to claim 1 or 2. 4. The computer is associated with a change in vertex coordinates of the polygon in the vertical direction, and the brightness at each vertex of the polygon is changed such that the upper vertex is bright and the lower vertex is dark, and hand setting the brightness in each polygon so as to interpolate the luminance of each vertex
The image forming method according to claim 1, wherein the image forming method also functions as a step . 5. The image forming method according to claim 1, wherein the water surface model is configured by arranging a large number of rectangular polygons in a grid pattern. 6. A computer is used to express data regarding coordinates of vertices of a large number of polygons for forming a water surface model and a water surface pattern to be mapped to a plurality of polygons included in a predetermined range of the water surface model. a storage unit and data regarding the texture is recorded, serial in said storage means based on the information specifying the water surface movements
Correspondence between the means for changing the vertical coordinates of the recorded vertex coordinates of each polygon and the vertex of each polygon included in the predetermined range recorded in the storage means and the coordinate on the texture. A computer-readable storage medium having a program recorded thereon for causing the polygon to function as a means for mapping the texture on each polygon while changing the coordinate of the vertex in the vertical direction as a variable. 7. A computer-readable storage medium having recorded therein information for executing the image forming method according to any one of claims 2 to 5 by a computer. 8. A game system provided with a game control device configured as a computer for realizing the image forming method according to claim 1.