JP4318240B2 - Image generation system and information storage medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image generation system and an information storage medium.
[0002]
[Background Art and Problems to be Solved by the Invention]
2. Description of the Related Art Conventionally, an image generation system that generates an image that can be seen from a given viewpoint in an object space that is a virtual three-dimensional space is known, and is popular as being able to experience so-called virtual reality. Taking an image generation system that can enjoy a racing game as an example, a player operates a car (object) to run in an object space, and competes with other players and cars operated by a computer to achieve a three-dimensional Enjoy the game.
[0003]
In such an image generation system, it is an important technical problem to generate a more realistic image in order to improve the player's virtual reality. Therefore, taking a racing game as an example, it is desirable to realize an expression in which dirt gradually adheres to the surface of a car as the course laps are repeated.
[0004]
As one method for expressing the dirt of a car in such a racing game, for example, a technique of sequentially replacing dirt textures mapped to cars (textures representing dirt) can be considered. That is, when the travel distance of the car is short, a dirt texture with a low degree of dirt is mapped to the car. As the mileage of the car increases, a dirt texture with a medium degree of dirt is mapped onto the car. When the travel distance of the car further increases, a dirt texture having a high degree of dirt is mapped onto the car.
[0005]
However, with this method, it is necessary to prepare in advance many types of textures with different levels of dirt. Accordingly, the use storage capacity of the memory for storing the texture increases, which causes the problem of large scale and high cost of the image generation system.
[0006]
The present invention has been made in view of the above problems, and an object of the present invention is to provide an image generation system capable of realizing realistic image expression such as dirt on an object while saving use storage capacity of a texture. And providing an information storage medium.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides an image generation system for generating an image, wherein the first object data including shape data of the first object and the same shape as the first object or Second object data including shape data of a second object having substantially the same shape; a first texture mapped to the first object; a first texture mapped to the second object; Is a drawing means for drawing the second object on the first object based on the second texture having a different texture pattern, and a transparency control means for variably controlling the transparency of the second object; It is characterized by including. The information storage medium according to the present invention is an information storage medium that can be used by a computer, and includes a program for executing the above means. The program according to the present invention is a program (including a program embodied in a carrier wave) that can be used by a computer, and includes a processing routine for executing the above means.
[0008]
According to the present invention, the second object to which the second texture is mapped is overlaid on the first object to which the first texture is mapped. Then, the transparency of the second object is variably controlled. Therefore, by changing the transparency and gradually changing the second object from completely transparent to semi-transparent, it is possible to express an image such that the second texture gradually becomes noticeable. On the other hand, by changing the transparency and gradually changing the second object to be transparent, it is possible to express an image such that the second texture gradually disappears and disappears. Therefore, compared to the technique of sequentially replacing a plurality of textures, a more diverse and realistic image expression can be realized with a small storage capacity of the texture.
[0009]
The image generation system, the information storage medium, and the program according to the present invention are characterized in that the second texture is a texture for expressing dirt on the first object. By doing in this way, it is possible to perform an image expression in which the dirt of the object becomes conspicuous and an image expression in which the dirt of the object gradually disappears.
[0010]
The image generation system, information storage medium, and program according to the present invention include means (or a program or processing routine for executing the means) for calculating movement or motion of the first object, and the second object. The object moves or moves following the first object. By doing in this way, realistic expression such as dirt of an object moving or operating in the object space becomes possible.
[0011]
In the image generation system, the information storage medium, and the program according to the present invention, the second object is composed of a plurality of part objects, and the transparency control means independently sets the transparency of each of the plurality of part objects. It is characterized by controlling. In this way, it is possible to vary the degree of change in transparency in each part of the object, and more various image representations are possible.
[0012]
In the image generation system, the information storage medium, and the program according to the present invention, the drawing unit has the same shape or substantially the same shape as the first object, and the third texture is different in texture pattern from the first texture. The third to Nth objects to which the Nth (N ≧ 3) texture is mapped are drawn on the first object together with the second object, and the transparency control means includes the second to second objects. The transparency of each of the Nth objects is controlled independently. In this way, for example, when the first event occurs, the transparency of the second object is changed, and when the second event occurs, the transparency of the third object is changed. It becomes possible, and the realism of an image can be increased.
[0013]
In the image generation system, information storage medium, and program according to the present invention, the first object data after geometry processing is stored in the storage means, and the drawing means stores the stored first object data after geometry processing. , And used as the second object data.
[0014]
According to the present invention, the first object data after the geometry processing is stored in the storage means and saved without being erased. Then, the first object is drawn based on the first object data after the geometry processing and the first texture. Then, the second object drawn by the saved first object data after the geometry processing and the second texture is overlaid on the first object. By doing so, it is possible to reduce the burden of the process of drawing the second object on the first object.
[0015]
The image generation system, information storage medium, and program according to the present invention include a Z shift unit that adds or subtracts a Z shift value to at least one of the Z value of the first object and the Z value of the second object. Or a program or a processing routine for executing the means. In this way, the second object can always be displayed in front of the first object.
[0016]
In the image generation system, the information storage medium, and the program according to the present invention, the Z shift means may perform the Z value of the primitive surface of the first object after the geometry processing and the Z value of the primitive surface of the second object after the geometry processing. A Z shift value is added to or subtracted from at least one of the values. In this way, it is possible to solve the problem that an error occurs in hidden surface removal due to a calculation error of the interpolation processing with a small processing load.
[0017]
The image generation system, the information storage medium, and the program according to the present invention include a scaling unit (or a unit for executing the unit) that performs a process for slightly increasing the size of the second object than the size of the first object. Program, processing routine). In this way, the second object can always be displayed in front of the first object.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Hereinafter, a case where the present invention is applied to a racing game will be described as an example. However, the present invention is not limited to this and can be applied to various games.
[0019]
1. Constitution
FIG. 1 shows an example of a block diagram of this embodiment. In this figure, the present embodiment may include at least the processing unit 100 (or may include the processing unit 100 and the storage unit 170, or the processing unit 100, the storage unit 170, and the information storage medium 180), and other blocks. (For example, the operation unit 160, the display unit 190, the sound output unit 192, the portable information storage device 194, and the communication unit 196) can be arbitrary constituent elements.
[0020]
Here, the processing unit 100 performs various processes such as control of the entire system, instruction instruction to each block in the system, game processing, image processing, sound processing, and the like. , DSP, etc.) or ASIC (gate array, etc.) or a given program (game program).
[0021]
The operation unit 160 is for a player to input operation data, and the function can be realized by hardware such as a lever, a button, and a housing.
[0022]
The storage unit 170 serves as a work area such as the processing unit 100 or the communication unit 196, and its function can be realized by hardware such as a RAM.
[0023]
An information storage medium (storage medium usable by a computer) 180 stores information such as programs and data, and functions thereof are an optical disk (CD, DVD), a magneto-optical disk (MO), a magnetic disk, and a hard disk. It can be realized by hardware such as a magnetic tape or a memory (ROM). The processing unit 100 performs various processes of the present invention (this embodiment) based on information stored in the information storage medium 180. That is, the information storage medium 180 stores information (program or data) for executing the means of the present invention (this embodiment) (particularly, the blocks included in the processing unit 100).
[0024]
Part or all of the information stored in the information storage medium 180 is transferred to the storage unit 170 when the system is powered on. Information stored in the information storage medium 180 includes program code, image data, sound data, display object shape data, table data, list data, and data for instructing the processing of the present invention. It includes at least one of information, information for performing processing according to the instruction, and the like.
[0025]
The display unit 190 outputs an image generated according to the present embodiment, and the function thereof can be realized by hardware such as a CRT, LCD, or HMD (head mounted display).
[0026]
The sound output unit 192 outputs the sound generated by the present embodiment, and its function can be realized by hardware such as a speaker.
[0027]
The portable information storage device 194 stores player personal data, save data, and the like. As the portable information storage device 194, a memory card, a portable game device, and the like can be considered.
[0028]
The communication unit 196 performs various controls for communicating with the outside (for example, a host device or other image generation system), and functions as hardware such as various processors or a communication ASIC. Or by a program.
[0029]
The program or data for executing the means of the present invention (this embodiment) may be distributed from the information storage medium of the host device (server) to the information storage medium 180 via the network and the communication unit 196. Good. Use of such an information storage medium of the host device (server) is also included in the scope of the present invention.
[0030]
The processing unit 100 includes a game processing unit 110, an image generation unit 130, and a sound generation unit 150.
[0031]
Here, the game processing unit 110 receives coins (cost), various mode setting processing, game progress processing, selection screen setting processing, object position and rotation angle (rotation angle around X, Y, or Z axis). Processing for moving objects, processing for moving objects (motion processing), processing for determining viewpoint positions (virtual camera positions) and line-of-sight angles (virtual camera rotation angles), processing for placing objects such as map objects in the object space, Operation data from the operation unit 160 includes various game processes such as a hit check process, a process for calculating game results (results, results), a process for a plurality of players to play in a common game space, or a game over process. Or based on personal data, stored data, game programs, etc. from the portable information storage device 194. Carried out.
[0032]
The game processing unit 110 includes a movement / motion calculation unit 114.
[0033]
Here, the movement / motion calculation unit 114 calculates movement information (position data, rotation angle data) and movement information (position data of each part of the object, rotation angle data) of an object such as a car. Based on operation data input by the player through the operation unit 160, a game program, or the like, a process of moving or moving an object is performed.
[0034]
More specifically, the movement / motion calculation unit 114 performs processing for obtaining the position and rotation angle of the object every frame (1/60 seconds), for example. For example, the position of the object in the (k-1) frame is PMk-1, the speed is VMk-1, the acceleration is AMk-1, and the time of one frame is Δt. Then, the position PMk and speed VMk of the object in the k frame are obtained by the following equations (1) and (2), for example.
[0035]
PMk = PMk-1 + VMk-1 * .DELTA.t (1)
VMk = VMk-1 + AMk-1 * .DELTA.t (2)
The image generation unit 130 performs various types of image processing in accordance with instructions from the game processing unit 110, for example, generates an image that can be seen from a given viewpoint in the object space, and outputs the image to the display unit 190. In addition, the sound generation unit 150 performs various types of sound processing in accordance with instructions from the game processing unit 110, generates sounds such as BGM, sound effects, and voices, and outputs them to the sound output unit 192.
[0036]
Note that all of the functions of the game processing unit 110, the image generation unit 130, and the sound generation unit 150 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.
[0037]
The image generation unit 130 includes a geometry processing unit 132 (three-dimensional coordinate calculation unit), a transparency control unit 134, a Z shift unit 136, and a drawing unit 140 (rendering unit).
[0038]
Here, the geometry processing unit 132 performs various types of geometry processing (three-dimensional coordinate calculation) such as coordinate transformation, clipping processing, perspective transformation, or light source calculation. In the present embodiment, object data after geometric processing (after perspective transformation) (shape data such as vertex coordinates of objects, vertex texture coordinates, luminance data, etc.) is stored in the main memory 172 of the storage unit 170. Saved.
[0039]
The transparency control unit 134 performs a process of variably controlling the transparency (equivalent to translucency and opacity) of the dirt expression object (second object) drawn on the car object (first object). Here, the dirt expression object has the same shape (or almost the same shape) as the car object, but a texture (dirt texture) of a pattern different from the texture mapped to the car object (car ground texture) is mapped. The
[0040]
Note that the transparency to be controlled by the transparency control unit 134 is particularly preferably the transparency set for each polygon (primitive surface in a broad sense) from the viewpoint of reducing the processing load. It may be set transparency (alpha value of each pixel). That is, the transparency control unit 134 may directly rewrite the transparency (α value) of the texture stored in the texture storage unit.
[0041]
The Z shift unit 136 performs a process of adding or subtracting (adding or subtracting) the Z shift value to at least one of the Z value (depth value) of the car object and the Z value of the dirt expression object. More specifically, the Z shift value is added to or subtracted from at least one of the Z value of the polygon (primitive surface) of the car object after geometry processing and the Z value of the polygon of the dirt expression object after geometry processing. In this way, it is possible to always display the dirt expression object in front of the car object. Also, the problem of hidden surface removal errors in the Z buffer method can be solved.
[0042]
Instead of providing the Z shift unit 136, a scaling unit 138 may be provided. The scaling unit 138 performs a process for slightly increasing the size of the dirt expression object to be larger than the size of the car object. This also makes it possible to always display the dirt expression object in front of the car object.
[0043]
The drawing unit 140 stains the car object based on the object data of the car object, the object data of the dirt expression object, the background texture mapped to the car object, the dirt texture mapped to the dirt expression object, and the like. A process of drawing the representation object in an overlapping manner is performed. In the present embodiment, the transparency of the dirt expression object is changed by the control process of the transparency control unit 134. This makes it possible to realize various and realistic stain expressions while suppressing the use storage capacity of the texture.
[0044]
Note that the interpolation unit 142 included in the drawing unit 140 obtains the Z value of each pixel of the polygon by interpolation calculation such as DDA based on the Z value of the vertex (for example, three vertices) of the polygon. The above-described Z shift unit 136 adds or subtracts a Z shift value larger than the calculation error in the interpolation unit 142 with respect to the polygon Z value.
[0045]
The hidden surface removal unit 144 included in the drawing unit 140 performs hidden surface removal according to the algorithm of the Z buffer method using the Z buffer 178 in which the Z value is stored.
[0046]
Note that the image generation system of the present embodiment may be a system dedicated to the single player mode in which only one player can play, or not only the single player mode but also a multiplayer mode in which a plurality of players can play. The system may also be provided.
[0047]
Further, when a plurality of players play, game images and game sounds to be provided to the plurality of players may be generated using one terminal, or connected via a network (transmission line, communication line) or the like. Alternatively, it may be generated using a plurality of terminals.
[0048]
2. Features of this embodiment
(1) Control of transparency
In this embodiment, as shown in FIG. 2, a car object OB1 (first object) and a dirt expression object OB2 (second object) having the same shape as OB1 but having a different texture to be mapped are prepared. Then, OB2 is drawn on the vehicle object OB1 while variably controlling the transparency TRANS (translucency, opacity) of the dirt expression object OB2. Thereby, as shown in B1 of FIG. 2, the dirt of the car can be expressed realistically.
[0049]
For example, when the vehicle starts to run, the transparency TRANS of the dirt expression object OB2 is set to 0 (%). By doing so, the vehicle OB2 becomes completely transparent, and a car without dirt is displayed.
[0050]
Then, when an event such as a car entering a muddy water area or the like occurs or the travel distance of the car increases, the transparency TRANS of OB2 is gradually increased. As a result, OB2 changes from transparent to translucent, and the dirt on the car gradually becomes noticeable.
[0051]
On the other hand, when an event occurs such as the car getting out of the muddy water area or taking a clean water, the transparency TRAN of OB2 is gradually reduced. This makes it possible to express how the dirt on the car gradually drops.
[0052]
For example, as another technique for expressing dirt on a car, a technique of sequentially replacing dirt textures mapped on the car can be considered.
[0053]
However, with this method, it is necessary to prepare in advance many types of textures with different levels of dirt. Therefore, the use storage capacity of the texture increases, which causes the problem of large scale and high cost of the image generation system.
[0054]
According to the present embodiment, it is possible to express a plurality of stages of dirt states with a simple process of simply changing the transparency TRANS of the dirt representing object OB2. Since only the texture mapped to OB2 needs to be prepared as the dirt texture, the use storage capacity of the texture can be saved. That is, it is possible to express more realistic and diverse stains with a small storage capacity.
[0055]
Note that the second texture mapped to the second object is particularly preferably a texture for expressing the dirt of the first object, but is not limited thereto. For example, various textures such as an environmental texture for expressing the reflection of a car and a bump texture for expressing surface irregularities can be considered.
[0056]
In the present embodiment, as shown in FIG. 3, the dirt expression object OB2 moves (or moves) following the car object OB1. That is, when the car object OB1 moves (parallel movement, rotational movement), the position PM (representative point) of the car object OB1 and the position PM ′ of the dirt expression object are always the same, and the direction (rotation angle) that faces is also the same. Always the same. By doing so, it becomes possible to express dirt on an object that moves and rotates like a car.
[0057]
In this embodiment, as shown in FIG. 4, the dirt expression object OB2 is composed of a plurality of part objects OB2-1, OB2-2, and OB2-3, and these OB2-1, OB2-2, and OB2-3. The transparency levels of TRANSA, TRANSB, and TRANSC may be controlled independently.
[0058]
For example, when the increase rates of transparency TRANSA, TRANSB, and TRANSC with respect to the travel distance of the vehicle are ΔTRANSA, ΔTRANSB, and ΔTRANSC, respectively, ΔTRANSA>ΔTRANSB> ΔTRANSC is set. In this way, when the mileage of the vehicle increases, the front portion of the vehicle becomes more noticeable in the dirt earlier than the rear portion. As a result, the realism and diversity of car dirt expression can be increased.
[0059]
The configuration form of the part object of the dirt expression object OB2 is not limited to that shown in FIG. For example, you may divide | segment into a finer part object like a car bumper, a fender, a bonnet, a door, a windshield, a window, and a trunk. Alternatively, the transparency of only part of the part object may be changed, and the transparency of other parts may not be changed.
[0060]
In this embodiment, as shown in FIG. 5, two or more dirt expression objects OB2, OB3, OB4... Having different texture patterns are prepared, and these OB2, OB3, OB4. You may make it draw on OB1. Then, the transparency levels of OB2, OB3, OB4,..., TRANSA, TRANSB, TRANSC,.
[0061]
For example, when the car enters the muddy water area, the transparency TRANSA of the muddy water dirt expression object OB2 is changed. When the vehicle enters the dust area, the transparency TRANSB of the dust dirt expression object OB3 is changed. When the car enters the rain area, the transparency TRANSC of the rain dirt expression object OB4 is changed. If it does in this way, according to the running area and running situation of a car, it will come to be attached to dirt which is different in a car. This result can further increase the variety of stain expression and the realism of the image.
[0062]
(2) Reuse of object data after geometry processing
Now, as a technique to draw a dirt object on a car object, prepare a car object and a dirt object separately, and perform geometry processing (coordinate transformation, clipping processing, perspective transformation) on each of these objects. Or a light source calculation etc.) can be considered separately.
[0063]
However, according to this method, the processing load is about twice that in the case where only the car object is drawn without using the dirt expression object. This increase in processing load becomes a serious problem in an image generation system that requires real-time processing that all drawing processing must be completed within one frame.
[0064]
Therefore, in the present embodiment, the object data of the car object after the geometry processing is saved in the main memory, and the saved object data after the geometry processing is reused as the object data of the dirt expression object. . Thereby, the problem of the increase in the processing burden can be solved.
[0065]
More specifically, as shown in FIG. 6A1, geometry processing is performed based on the object data (vertex coordinates, vertex texture coordinates, luminance, normal vector, etc.) of the car object in the main memory, and the geometry The object data after processing (after perspective transformation) is stored in the main memory and saved without being erased.
[0066]
Next, as shown in FIG. 6A2, the background texture of the car is transferred to the texture storage unit (texture storage area) of the VRAM (may be transferred before the geometry process).
[0067]
Next, as shown in (A3) of FIG. 6, the car object is drawn in the frame buffer of the VRAM based on the object data after the geometry processing and the background texture of the car stored in the texture storage unit. As a result, the car object to which the background texture is mapped is drawn on the frame buffer.
[0068]
Next, as shown in (A4) of FIG. 6, the dirt texture is transferred to the texture storage unit, and the texture mapped to the object is changed.
[0069]
Next, as shown in (A5) of FIG. 6, the frame buffer is used for expressing dirt based on the object data after geometry processing stored in the main memory and the dirty texture stored in the texture storage unit. Draw objects by alpha blending. Thus, the dirt expression object to which the dirt texture is mapped is drawn on the car object to which the ground texture is mapped.
[0070]
By performing the above processing in one frame, it becomes possible to draw a dirt expression object on a car object.
[0071]
In this embodiment, the object data of the car object after the geometry processing already stored in the main memory is reused as the object data of the dirt expression object. Accordingly, it is not necessary to perform the geometry processing on the dirt expression object again, and only one time is required, so that the car dirt expression can be realized without increasing the processing load so much.
[0072]
In particular, the geometry processing (three-dimensional coordinate calculation) needs to be performed on all the vertices of the object, and is a very heavy processing. Therefore, the processing load can be greatly reduced by performing this geometry processing only once instead of performing it twice.
[0073]
(3) Z shift processing and scaling processing
Now, when drawing a car object and a dirt expression object on top of each other, if the dirt expression object does not always come in front of the car object, the car dirt will be hidden behind the ground and will not be displayed. Arise.
[0074]
In order to prevent such a situation, it is desirable to add or subtract the Z shift value with respect to the Z value (depth value) of the car object or the Z value of the object for expressing dirt. That is, Z shift processing for adding / subtracting the Z shift value to at least one of these objects is performed so that the dirt expression object is always displayed in front of the car object. By doing in this way, the situation where the dirt of a car hides in the ground can be prevented.
[0075]
Instead of adding and subtracting such a Z shift value, a scaling process may be performed in which the size of the dirt expression object is slightly larger than the size of the car object. In this way, the dirt expression object can always be displayed in front of the car object. However, such scaling processing has a drawback that the processing load is heavy compared to the Z shift processing. Therefore, the Z shift process is more desirable from the viewpoint of reducing the processing load.
[0076]
Now, in the image generation system as in the present embodiment, it is necessary to erase the hidden surface in order to erase the portion that cannot be seen from the viewpoint and display only the portion that can be seen from the viewpoint. Typical examples of hidden surface removal include what is called a depth sorting method and what is called a Z buffer method.
[0077]
In the depth sorting method (Z sorting method), polygons (primitive surfaces) are sorted according to the distance from the viewpoint, and the polygons are drawn in order from the viewpoint. On the other hand, in the Z buffer method, a Z buffer for storing Z values (depth values) for all pixels (dots) on the screen is prepared, and hidden surface erasure is performed using this Z buffer.
[0078]
When performing hidden surface removal using such a Z-buffer method, the following method may be employed to always display the dirt expression object in front of the car object.
[0079]
That is, first, the geometry processing unit 132 in FIG. 1 transfers the object data (polygon data) of the car object to the drawing unit 140, and then transfers the object data of the dirt expression object to the drawing unit 140. Then, the hidden surface removal unit 144 included in the drawing unit 140 performs processing so as to overwrite the pixel to which the object data is transferred later for pixels having the same Z value. By adopting such a method, it is possible to always display the dirt expression object in front of the car object without performing the Z shift process and the scaling process.
[0080]
However, even when such a method is adopted, it is caused by an error in the interpolation calculation (calculation for obtaining the Z value of each pixel of the polygon based on the Z value of each vertex of the polygon) in the interpolation unit 142 of FIG. Thus, it has been found that a display error occurs in which each part of the vehicle object that should be displayed behind is displayed in front of the dirt expression object. Hereinafter, this display error problem will be described in detail.
[0081]
For example, the polygon shape that can be handled by the drawing unit 140 of FIG. 1 may be fixed to a fixed shape in order to speed up the drawing process. More specifically, the drawing unit 140 may handle only triangular polygons due to its specifications. In such a case, a polygon having four or more vertices needs to be divided into triangular polygons before transferring the data to the drawing unit 140.
[0082]
However, in such polygon division, it has been found that even if polygons have vertices with the same coordinates, the vertex configuration of the triangular polygon after division may be different depending on the division method. did.
[0083]
For example, in FIG. 7A, the polygon PL1 is divided into triangular polygons PA1 and PB1, and the polygon PL2 is divided into triangular polygons PA2 and PB2. In this case, PA1 and PA2, and PB1 and PB2 are triangular polygons having the same shape (vertex), so that correct display is performed.
[0084]
On the other hand, in FIG. 7B, the polygon PL1 is divided into triangular polygons PA1 and PB1, and the polygon PL2 is divided into triangular polygons PC2 and PD2. In this case, PA1 and PC2, and PB1 and PD2 are triangular polygons having different shapes, which causes a display error. That is, the context of the polygons is out of order, and a situation occurs in which pixels of the polygon PL1 that should be hidden behind are displayed in front of the polygon PL2.
[0085]
That is, the interpolation unit 142 in FIG. 1 calculates the Z value of each pixel (dot) of the polygon by a technique such as DDA based on the Z value of the vertex of the polygon. However, this interpolation processing usually has a calculation error (cumulative error) of about 1 LSB, for example. This calculation error can be reduced if the hardware configuration or the like of the interpolation unit 142 is made high-performance, but this causes an increase in hardware cost. Therefore, it is substantially extremely difficult to make this calculation error zero.
[0086]
On the other hand, when the Z value is the same, the hidden surface removal unit 144 in FIG. 1 is normally set to overwrite the data transferred later.
[0087]
In the case of FIG. 7A, the triangular polygons PA1 and PA2 and PB1 and PB2 have the same shape (vertex). Therefore, the Z value of each pixel of PA1 and PA2 obtained by the interpolation processing is the same even if there is a calculation error. Similarly, the Z value of each pixel of PB1 and PB2 obtained by the interpolation processing is the same even if there is a calculation error. Accordingly, in this case, in all the pixels, the polygon PA2 is overwritten on the polygon PA1, and the polygon PB2 is overwritten on the polygon PB1. Therefore, the polygon is drawn as set and the display is correct.
[0088]
However, in the case of FIG. 7B, the shapes of the triangular polygons PA1 and PC2 and PB1 and PD2 are different. Therefore, the Z value of each pixel of PA1 and PC2 obtained by the interpolation process should be the same value, but may have a different value due to the existence of an operation error. Similarly, the Z value of each pixel of PB1 and PD2 obtained by the interpolation process may be different due to the existence of a calculation error. For this reason, a situation occurs in which the pixels of the polygons PA1 and PB1 that should be hidden are displayed in front of the polygons PC2 and PD2, resulting in an error display.
[0089]
Therefore, in the present embodiment, a technique as shown in FIG. 8 is adopted in order to solve such a problem.
[0090]
That is, the Z shift value is added to or subtracted from at least one of the Z value of the polygon PL1 of the car object after the geometry process and the Z value of the polygon PL2 of the dirt expression object after the geometry process. For example, in FIG. 8, the Z shift value is added to the Z value of the polygon PL1, or the Z shift value is subtracted from the Z value of the polygon PL2 (when the Z value increases as the distance from the viewpoint increases). By doing so, even if there is a calculation error in the interpolation processing, the polygon PL2 of the dirt expression object is correctly overwritten on the polygon PL1 of the car object. As a result, the dirt expression object is always displayed in front of the car object, and an appropriate car dirt expression can be realized.
[0091]
Now, it is desirable that the magnitude of the Z shift value to be added to or subtracted from the Z value is larger than the DDA calculation error in the interpolation unit 142 in FIG.
[0092]
More specifically, as shown in FIG. 9, when the DDA calculation error is, for example, −N × LSB to N × LSB, the magnitude of the Z shift value to be added or subtracted is − (N + K) × LSB to (N + K) × LSB (where K ≧ 1). In this way, it is possible to effectively solve the problem of hidden surface removal errors caused by calculation errors.
[0093]
It is desirable to determine which polygon's Z value the Z shift value is added to or subtracted from based on identification information set in advance in association with the polygon (or object).
[0094]
For example, in the table of FIG. 10, a shift flag SFL (identification information for identifying whether a polygon is a target of addition / subtraction of a Z shift value) indicating whether or not to perform Z shift processing is associated with each polygon in advance. Is set. For example, in FIG. 10, Z shift processing is performed for polygons PL1, PL3, and PL4 with SFL of 1, and Z shift processing is not performed for polygon PL2 with SFL of 0. . By making such settings in advance, it becomes possible to easily determine which polygon is the processing target in the Z shift processing. Thereby, the processing burden can be greatly reduced.
[0095]
3. Processing of this embodiment
Next, a detailed example of the processing of this embodiment will be described using the flowcharts of FIGS.
[0096]
FIG. 11 is a flowchart relating to the transparency control processing of the dirt expression object.
[0097]
First, it is determined whether or not the vehicle has entered the muddy water area (step S1). This determination is made based on vehicle position data, muddy water position data, and the like.
[0098]
If the car has entered the muddy water area, the transparency TRANS of the dirt expression object is increased (step S2). As a result, the dirt expression object that was initially completely transparent becomes translucent, and the dirt on the car gradually becomes more noticeable. On the other hand, when the vehicle has not entered the muddy water area, the process proceeds to step S5.
[0099]
Next, it is determined whether or not the transparency TRANS is 100 (%) or higher (step S3). If it is 100 (%) or higher, TRANS = 100 (%) is fixed (step S4).
[0100]
Next, it is determined whether or not the vehicle has escaped from the muddy water area (step S5). Then, when the car escapes from the muddy water area, it is determined whether or not the transparency TRANS is larger than 50 (%) (step S6). If it is larger, the transparency TRANS is gradually reduced (step S7). As a result, the object for expressing dirt gradually becomes transparent, and it becomes possible to express a situation in which the dirt on the car gradually falls.
[0101]
Next, it is determined whether or not the transparency TRANS of the dirt expression object is 0 (%) (step S8). If TRANS is not 0 (%), the dirt expression object is superimposed on the car object with the transparency TRANS. Drawing is performed (step S9). On the other hand, when TRANS = 0 (%), the processing in step S9 is omitted to reduce the processing load.
[0102]
FIG. 12 is a flowchart illustrating a processing example of a method of reusing object data after geometry processing.
[0103]
First, geometry processing is performed based on object data. That is, the vehicle object is coordinate-transformed from the local coordinate system to the world coordinate system (step S11), and then coordinate-transformed from the world coordinate system to the viewpoint coordinate system (step S12). Then, clipping processing is performed (step S13), and perspective transformation to the screen coordinate system is performed (step S14).
[0104]
Next, as described with reference to FIG. 6, the object data of the car object after the perspective transformation (after the geometry processing) is stored in the main memory and saved (step S15). Then, the background texture to be mapped to the car object is transferred to the VRAM (step S16).
[0105]
Next, the car object is drawn in the frame buffer based on the object data after the perspective transformation stored in the main memory in step S15 and the background texture of the car transferred to the VRAM in step S16 (step S17).
[0106]
Next, the dirt texture is transferred to the VRAM (step S18). Then, based on the object data after perspective transformation saved in the main memory in step S15 and the dirt texture transferred to the VRAM in step S18, a dirt expression object is drawn in the frame buffer (step S19). That is, the dirt expression object to which the dirt texture is mapped is overwritten on the car object already drawn in step S17 by α blending processing or the like.
[0107]
When performing the Z shift process as shown in FIG. 8, for example, after step S14 in FIG. 12, it is determined based on the shift flag SFL in FIG. 10 whether or not to perform the Z shift process on the polygon to be processed. Insert processing. If it is determined that the Z shift process is to be performed, a given Z shift value may be added to or subtracted from the Z value of the polygon (Z value of the vertex of the polygon).
[0108]
4). Hardware configuration
Next, an example of a hardware configuration capable of realizing the present embodiment will be described with reference to FIG.
[0109]
The main processor 900 operates based on a program stored in the CD 982 (information storage medium), a program transferred via the communication interface 990, or a program stored in the ROM 950 (one of information storage media). Various processes such as processing, image processing, and sound processing are executed.
[0110]
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, if a physical simulation for moving or moving an object requires processing such as matrix operation, a program operating on the main processor 900 instructs (requests) the processing to the coprocessor 902. )
[0111]
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 computation, and performs matrix computation (vector computation). Run fast. For example, when processing such as coordinate transformation, perspective transformation, and light source calculation is performed, a program operating on the main processor 900 instructs the geometry processor 904 to perform the processing.
[0112]
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. As a result, a moving image compressed by the MPEG method or the like can be displayed on the opening screen, the intermission screen, the ending screen, or the game screen. Note that the image data and sound data to be decoded are stored in the ROM 950 and the CD 982 or transferred from the outside via the communication interface 990.
[0113]
The drawing processor 910 performs 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 transfer the texture to the texture storage unit 924 if necessary. Then, the rendering processor 910 renders the object in the frame buffer 922 at high speed while performing hidden surface removal using a Z buffer or the like based on the object data and texture. The drawing processor 910 can also perform α blending (translucent processing), mip mapping, fog processing, trilinear filtering, anti-aliasing, shading processing, and the like. When an image for one frame is written in the frame buffer 922, the image is displayed on the display 912.
[0114]
The sound processor 930 includes a multi-channel ADPCM sound source and the like, and generates high-quality game sounds such as BGM, sound effects, and sounds. The generated game sound is output from the speaker 932.
[0115]
Operation data from the game controller 942, save data from the memory card 944, and personal data are transferred via the serial interface 940.
[0116]
The ROM 950 stores system programs and the like. In the case of an arcade game system, the ROM 950 functions as an information storage medium, and various programs are stored in the ROM 950. A hard disk may be used instead of the ROM 950.
[0117]
The RAM 960 is used as a work area for various processors.
[0118]
The DMA controller 970 controls DMA transfer between the processor and memory (RAM, VRAM, ROM, etc.).
[0119]
The CD drive 980 drives a CD 982 (information storage medium) in which programs, image data, sound data, and the like are stored, and enables access to these programs and data.
[0120]
The communication interface 990 is an interface for transferring data to and from the outside via a network. In this case, as a network connected to the communication interface 990, a communication line (analog telephone line, ISDN), a high-speed serial bus, or the like can be considered. By using a communication line, data transfer via the Internet becomes possible. Further, by using the high-speed serial bus, data transfer between other image generation systems and other game systems becomes possible.
[0121]
All of the means of the present invention may be executed by hardware alone, or may be executed only by a program stored in an information storage medium or a program distributed via a communication interface. Alternatively, it may be executed by both hardware and a program.
[0122]
When each means of the present invention is executed by both hardware and a program, a program for executing each means of the present invention using hardware is stored in the information storage medium. Become. More specifically, the program instructs each processor 902, 904, 906, 910, 930, etc., which is hardware, and passes data if necessary. Each processor 902, 904, 906, 910, 930, etc. executes each means of the present invention based on the instruction and the passed data.
[0123]
FIG. 14A shows an example in which the present embodiment is applied to an arcade game system. The player enjoys the game by operating the lever 1102, the button 1104, and the like while viewing the game image displayed on the display 1100. Various processors and various memories are mounted on the built-in system board (circuit board) 1106. Information (program or data) for executing each means of the present invention is stored in a memory 1108 which is an information storage medium on the system board 1106. Hereinafter, this information is referred to as storage information.
[0124]
FIG. 14B shows an example in which the present embodiment is applied to a home game system. The player enjoys the game by operating the game controllers 1202 and 1204 while viewing the game image displayed on the display 1200. In this case, the stored information is stored in the CD 1206, which is an information storage medium that is detachable from the main system, or in the memory cards 1208, 1209, and the like.
[0125]
FIG. 14C shows a host apparatus 1300 and terminals 1304-1 to 1304-n connected to the host apparatus 1300 via a network 1302 (a small-scale network such as a LAN or a wide area network such as the Internet). An example of applying this embodiment to a system including In this case, the stored information is stored in an information storage medium 1306 such as a magnetic disk device, a magnetic tape device, or a memory that can be controlled by the host device 1300, for example. When the terminals 1304-1 to 1304-n can generate game images and game sounds stand-alone, the host device 1300 receives a game program and the like for generating game images and game sounds from the terminal 1304-. 1 to 1304-n. On the other hand, if it cannot be generated stand-alone, the host device 1300 generates a game image and a game sound, which is transmitted to the terminals 1304-1 to 1304-n and output at the terminal.
[0126]
In the case of the configuration shown in FIG. 14C, each unit of the present invention may be executed in a distributed manner between the host device (server) and the terminal. The storage information for executing each means of the present invention may be distributed and stored in the information storage medium of the host device (server) and the information storage medium of the terminal.
[0127]
The terminal connected to the network may be a home game system or an arcade game system. When connecting the arcade game system to a network, a portable information storage device capable of exchanging information with the arcade game system and exchanging information with the home game system. It is desirable to use (memory card, portable game device).
[0128]
The present invention is not limited to that described in the above embodiment, and various modifications can be made.
[0129]
For example, in the invention according to the dependent claims of the present invention, a part of the constituent features of the dependent claims can be omitted. Moreover, the principal part of the invention according to one independent claim of the present invention can be made dependent on another independent claim.
[0130]
Further, the texture mapped to the second object according to the present invention is particularly preferably a texture representing the dirt of the first object, but is not limited to this.
[0131]
Further, it is sufficient that the first object and the second object have the same shape (or almost the same shape) in a part thereof.
[0132]
In addition, the drawing process may be performed so that the first object is on the second object.
[0133]
In the present embodiment, coordinate transformation or perspective transformation is given as an example of the geometry processing, but the geometry processing of the present invention is not limited to these.
[0134]
Further, the texture mapped to the object is not limited to the texture of color information, but luminance information, translucent information (α value), surface shape information (bump value), reflectance information, refractive index information, or depth information. The texture about etc. may be sufficient.
[0135]
In addition to the racing game, the present invention can be applied to various games (a fighting game, a shooting game, a robot battle game, a sports game, a competition game, a role playing game, a music playing game, a dance game, etc.).
[0136]
Further, the present invention can be applied to various image generation systems such as a business game system, a home game system, a large attraction system in which a large number of players participate, a simulator, a multimedia terminal, and a system board for generating game images.
[Brief description of the drawings]
FIG. 1 is an example of a block diagram of an image generation system according to an embodiment.
FIG. 2 is a diagram for explaining a method for controlling the transparency of a dirt expression object.
FIG. 3 is a diagram for explaining a technique for causing a dirt expression object to follow a car object;
FIG. 4 is a diagram illustrating a method of configuring a dirt expression object with a plurality of part objects.
FIG. 5 is a diagram for explaining a method of overwriting two or more dirt expression objects on a car object.
FIG. 6 is a diagram for explaining a method of reusing object data after geometry processing.
FIGS. 7A and 7B are diagrams for explaining a display error problem caused by polygon division. FIGS.
FIG. 8 is a diagram for describing a Z shift process of the present embodiment.
FIG. 9 is a diagram for explaining a method for determining the magnitude of a Z shift value based on the magnitude of a calculation error of DDA.
FIG. 10 is a diagram for explaining a shift flag SFL (identification information).
FIG. 11 is a flowchart illustrating a detailed processing example of the present embodiment.
FIG. 12 is a flowchart illustrating a detailed processing example of the present embodiment.
FIG. 13 is a diagram illustrating an example of a hardware configuration capable of realizing the present embodiment.
FIGS. 14A, 14B, and 14C are diagrams illustrating examples of various types of systems to which the present embodiment is applied.
[Explanation of symbols]
OB1 car object (first object)
OB2 Dirt expression object (second object)
TRANS Transparency
100 processor
110 Game processor
114 Movement / motion calculation unit
130 Image generator
132 Geometry processing part
134 Transparency controller
136 Z shift section
138 Scaling unit
140 Drawing part
142 Interpolator
144 Hidden surface removal part
150 sound generator
160 Operation unit
170 Storage unit
172 Main memory
174 frame buffer
176 texture storage
178 Z buffer
180 Information storage medium
190 Display
192 sound output section
194 Portable information storage device
196 Communication Department

Claims (14)

An image generation system for generating an image,
First object data including shape data of the first object, second object data including shape data of a second object having the same shape or substantially the same shape as the first object, and the first object Based on the first texture mapped to the second object and the second texture mapped to the second object and having a texture pattern different from the first texture, the second object is the second object. A drawing means for drawing in layers,
Look contains a transparency control means for variably controlling the transparency of the second object,
The second object is composed of a plurality of part objects;
The transparency control means comprises:
An image generation system, wherein the transparency of each of the plurality of part objects is independently controlled . An image generation system for generating an image,
First object data including shape data of the first object, second object data including shape data of a second object having the same shape or substantially the same shape as the first object, and the first object Based on the first texture mapped to the second object and the second texture mapped to the second object and having a texture pattern different from the first texture, the second object is the second object. A drawing means for drawing in layers,
Transparency control means for variably controlling the transparency of the second object ;
An image generation system including a scaling unit configured to perform a process of slightly increasing the size of the second object to be larger than the size of the first object . Oite to claim 1,
An image generation system comprising Z shift means for adding or subtracting a Z shift value to at least one of a Z value of a first object and a Z value of a second object. In claim 3 ,
The Z shift means is
An image characterized by adding or subtracting a Z shift value to at least one of the Z value of the primitive surface of the first object after geometry processing and the Z value of the primitive surface of the second object after geometry processing Generation system. In any one of Claims 1 thru | or 4 ,
The image generation system, wherein the second texture is a texture for expressing dirt of the first object. In any one of Claims 1 thru | or 5 ,
Means for calculating movement or movement of the first object;
The image generation system, wherein the second object moves or moves following the first object. In any one of Claims 1 thru | or 6 .
The first object data after geometry processing is stored in the storage means,
The drawing means;
An image generation system using the stored first object data after geometry processing as the second object data. A computer- readable information storage medium,
First object data including shape data of the first object, second object data including shape data of a second object having the same shape or substantially the same shape as the first object, and the first object Based on the first texture mapped to the second object and the second texture mapped to the second object and having a texture pattern different from the first texture, the second object is the second object. A drawing means for drawing in layers,
Storing a program for causing a computer to function as a transparency control means for variably controlling the transparency of the second object,
The second object is composed of a plurality of part objects;
The transparency control means comprises:
An information storage medium characterized by independently controlling the transparency of each of the plurality of part objects . A computer- readable information storage medium,
First object data including shape data of the first object, second object data including shape data of a second object having the same shape or substantially the same shape as the first object, and the first object Based on the first texture mapped to the second object and the second texture mapped to the second object and having a texture pattern different from the first texture, the second object is the second object. A drawing means for drawing in layers,
Transparency control means for variably controlling the transparency of the second object ;
An information storage medium storing a program for causing a computer to function as scaling means for performing processing for slightly increasing the size of the second object than the size of the first object . In claim 8 ,
A program for further causing the computer to function as Z shift means for adding or subtracting a Z shift value to at least one of the Z value of the first object and the Z value of the second object is stored. Information storage medium. In claim 10 ,
The Z shift means is
Information on adding or subtracting a Z shift value to at least one of the Z value of the primitive surface of the first object after geometry processing and the Z value of the primitive surface of the second object after geometry processing Storage medium. In any of claims 8 to 11 ,
The information storage medium characterized in that the second texture is a texture for expressing dirt on the first object. In any one of Claims 8 thru | or 12 .
Further storing a program for causing a computer to function as means for calculating the movement or operation of the first object,
The information storage medium, wherein the second object moves or moves following the first object. In any one of Claims 8 thru | or 13 .
The first object data after geometry processing is stored in the storage means,
The drawing means;
An information storage medium using the stored first object data after geometry processing as the second object data.

Images