JP2003109035A - Image generation system, program and information storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image generation system capable of generating an image to which a real shadow is projected with little processing addition without performing complicated management of objects which makes a shadow and onto which the shadow is made, a program and an information storage medium. SOLUTION: This system generates an image. The system performs processing that calculates depth data of an object space seen from a light source in a pixel unit shadow image generation processing that uses the depth data of the object space seen from the light source to specify a shadow area made by the object space on a given primitive surface constituting the object space and generates a shadow image corresponding to the given primitive surface on the basis of the shadow area, and processing that maps the shadow image onto a corresponding primitive surface and generates an image in the object space seen from a given viewpoint.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as a method for expressing a shadow, a shadow texture is generated by rendering a shape of an object that produces a shadow as viewed from the light source direction, and a shadow texture is applied to an object affected by the shadow. There is a method called shadow map for mapping.

FIG. 22 is a diagram for explaining a shadow texture generated when performing a shadow map. When performing the shadow map, as shown in the figure, the chair object 810 is projected in the direction of the ray vector 820 to generate the shadow texture 830 of the chair object in the shadow texture region 840.

FIG. 23 is a diagram for explaining a case where a shadow of a chair object is added to a floor wall object by the shadow map method.

Reference numeral 810 is a chair object, and 850
Is a floor wall object. Reference numeral 830 is a shadow texture generated by projecting the chair object 810 in the direction of the ray vector 820.

By mapping the shadow texture 830 onto the floor wall object 850 as shown in the figure, an image of the floor wall object 850 'onto which the shadow of the chair object is mapped can be generated.

The shadow map is an effective method for generating an image in which the shadow of one object is reflected in another object.

However, in such a shadow map method,
Since it is necessary to manage the objects on the side where the shadow is cast and the side where the shadow is cast, there is a problem that the processing becomes complicated.

Further, if an image of a shadow of a certain object falling on itself is to be generated using the shadow map method, the following inconvenience occurs.
FIG. 24 is a diagram showing a state in which a shadow of an object is added to oneself using the shadow map method. Reference numeral 810 ′ is an image when the chair object shadow texture 830 generated by using the shadow map method is mapped to the chair object 810.

As described above, in the shadow map method, when a shadow is projected on an object that produces a shadow, the shadow is cast on all the objects. Therefore, an image in which the shadow is self-projected can be generated in real time. It was difficult. As a result, I couldn't express myself as if the light was blocked by myself and a shadow was cast on myself, resulting in an image that lacked reality.

The present invention has been made in view of the above problems, and an object of the present invention is to add a small amount of processing without performing complicated management of objects on the shadow casting side and the shadow side. An image generation system, an image generation method, a program, and an information storage medium capable of generating an image on which a realistic shadow is projected.

Another object of the present invention is to provide an image generating system, an image generating method, a program and an information storage medium capable of generating an image in which a realistic shadow is self-projected.

[0013]

(1) The present invention is a system for generating an image, and means for obtaining depth data of an object space viewed from a light source on a pixel-by-pixel basis and a given primitive forming the object space. The shadow area cast by the object space on the surface is specified using the depth data of the object space viewed from the light source,
Shadow image generation processing means for generating a shadow image corresponding to a given primitive surface based on the shadow area, and mapping the shadow image to the corresponding primitive surface to generate an image of the object space viewed from a given viewpoint. And means for performing a process of generating.

A program according to the present invention is a program that can be used by a computer (a program embodied in an information storage medium or a carrier wave), and is characterized by causing the computer to implement the above means. An information storage medium according to the present invention is characterized by including an information storage medium usable by a computer and a program for causing the computer to realize the above means.

An image generating method according to the present invention is characterized by including a step of causing a computer to implement the above means.

The depth data of the object space viewed from the light source is the depth data of the scene viewed from the light source to the object space, and is the depth information (for example, Z value) of the object space viewed or projected from the light source. For example, when the light source is a parallel light source, it is the depth data when projection conversion is performed.For example, when the light source is a point light source or spot light source, it is the depth data when perspective conversion is performed with the light source as the viewpoint. is there.

The depth data of the object space viewed from the light source can be obtained, for example, by drawing the state viewed from the light source of the object space.

The shadow area may be specified by using a given determination method of a depth test (for example, Z test) based on the depth data and the constituent points of the primitive surface.

The given primitive surface may be formed of, for example, a polygon or a free-form surface.

According to the present invention, the shadow area dropped by the object space for each primitive forming the object space is specified by using the depth data of the object space viewed from the light source, and each primitive surface is identified based on the shadow area. A corresponding shadow image can be generated.

Therefore, according to the present invention, it is not necessary to perform complicated management of the object on the side where the shadow is cast and the object on the side where the shadow is cast, and management addition and processing addition of the shadow image generation processing can be greatly reduced.

Further, according to the present invention, it is possible to generate a shadow cast on each of the primitive surfaces forming the object space, so that the shadow of each object is given by each object without any special processing. Self-projection can be realized automatically.

(2) Further, in the image generation system, program and information storage medium according to the present invention, the shadow image generation processing means gives a depth value given in relation to a given primitive surface viewed from the light source and an object space from the light source. The scene depth values are compared to determine the area within the drawing area of the given primitive surface viewed from the light source where the light from the light source is blocked by the object existing in the object space, and the given area is determined. It is characterized by performing a process of identifying a shadow area cast on the primitive surface by the object space.

(3) Further, in the image generation system, program and information storage medium according to the present invention, the depth data of the object space viewed from the light source is the depth data of the scene obtained by perspective or projection conversion of the object space viewed from the light source. , Given a depth test using a given decision method based on the depth values of the constituent points of a given primitive surface after perspective transformation or projection transformation seen from the light source and the depth data of the object space seen from the light source. The feature is that a shadow image corresponding to the primitive surface is generated.

The depth test performed here is an area (a shadow area of an object existing in the object space) in which the light from the light source is blocked by another object in the drawing area of the primitive surface perspectively or projected from the light source. Can be determined. That is, it is preferable that the depth test is capable of drawing a portion located deeper in the scene viewed from the light source.

The projection conversion is, for example, a case of parallel projection from a light source, or a case of projection conversion in the light ray direction in the case of a parallel light source.

Here, the depth value is, for example, depth information or Z value.

For example, when the depth data of the object space viewed from the light source is the depth data of the scene perspective-transformed from the light source, the depth of the vertex of a given primitive surface after the perspective conversion viewed from the light source. A depth test using a given judgment method is performed based on the depth data in the object space in terms of the value and the light source, and a shadow image corresponding to a given primitive surface is generated.

When the depth data of the object space viewed from the light source is the depth data of the scene obtained by projecting and converting the object space from the light source, the depth of the vertex of a given primitive surface after the projection conversion from the light source. A depth test using a given judgment method is performed based on the depth data in the object space in terms of the value and the light source, and a shadow image corresponding to a given primitive surface is generated.

(4) The image generation system, program and information storage medium according to the present invention generate the shadow image based on the coordinates of the constituent points of a given primitive surface after perspective transformation or projection transformation as seen from the light source. A feature of the present invention is that the texture coordinate coordinates when mapping to the corresponding primitive surface are determined and the mapping processing is performed.

When a given primitive surface is composed of polygons, the shadow image is mapped to the corresponding polygon based on the coordinates of the vertices of the polygon after perspective transformation or projection transformation as seen from the light source. The texture coordinate coordinates at that time are determined and mapping processing is performed.

When performing the depth test, it is possible to obtain the coordinates after perspective transformation or projection transformation of the constituent points of a given primitive surface as seen from the light source. Therefore, the processing can be efficiently performed by using the coordinates as texture coordinate coordinates such as UV coordinates and ST coordinates.

(5) In the image generation system, program and information storage medium according to the present invention, the shadow image generation processing means inverts the depth value of the constituent point of a given primitive surface after perspective transformation or projection transformation. Means for performing the processing, Z buffer inversion processing means for inverting the Z buffer holding the depth data of the object space viewed from the light source, and Z buffer inversion for a given primitive surface in which the depth values of constituent points are inverted. Means for performing a drawing process using a predetermined determination method of the depth test, using the processed Z buffer.

Here, the Z buffer is a buffer that holds values relating to the context from the viewpoint such as Z value, depth value, depth value, etc. in pixel units, and may be a buffer called by the name of depth buffer, for example.

The depth value represents a value relating to the context of the light source after perspective conversion or projection conversion as viewed from the light source, and may be called Z value or depth value.

Here, the inversion is a process of reversing the magnitude relation of the current depth value, and may be, for example, bit inversion or the like, and may be the case of reversing the magnitude relation of the depth value by another method.

The depth test is a method for determining a pixel to be drawn. When a new primitive is to be drawn, the depth value of the primitive drawn using the Z buffer and the depth value of the primitive drawn now are compared for each pixel. What is called a Z test, for example.

The predetermined determination method of the depth test is a determination method regarding the magnitude relationship between the depth value of the primitive drawn before and the depth value of the primitive drawn now, for example GRE.
ATER judgment, LESS judgment and GREAT REQUA
It is called L determination or LESEQUUAL determination, but the name is not limited to this.

For example, if the depth value of the Z buffer is A and the depth value of the primitive to be drawn is B, GR
The EATER judgment is a judgment method (drawing is successful when A> B) when the depth value (A) of the primitive to be drawn is larger than the depth value (B) of the Z buffer.
The REATEREQUAL judgment is a judgment method (drawing is successful when A ≧ B) when the depth value (A) of the primitive to be drawn is greater than or equal to the depth value (B) of the Z buffer, and the LESS judgment is If the depth value (A) of the primitive to be drawn is smaller than the depth value (B) of the Z buffer, the determination method (A
<Drawing succeeds when B), and the LESSEQUAL judgment is that the depth value (A) of the primitive to be drawn is Z
This is a determination method of drawing when the depth value of the buffer is smaller than or equal to the depth value (B) (drawing success when A ≦ B). Here, the depth values A and B may be smaller in the depth direction or may be larger in the depth direction.

According to the present invention, drawing processing is performed using a given primitive after perspective transformation or projection transformation in which the depth value of the vertex is inverted and the Z buffer subjected to the Z buffer inversion processing.

At this time, when the depth test based on the GREETER determination is performed and the drawing process is performed, the Z value of the vertex is not inverted (normal) The given primitive after the perspective transformation or the projection transformation and the Z buffer inversion processing are performed. It is possible to obtain the same result as when the drawing process is performed by performing the depth test by the LESS determination using the (normal) Z buffer which is not processed.

Therefore, for example, even when the image is generated by using the hardware which cannot make the LESS judgment only by the GREETER judgment, by using the method of the present invention, the L
The depth test based on the ESS judgment can be simulated.

Note that recent hardware often has a function of automatically interpolating the Z value of pixels between the vertices of the primitive surface when drawing the primitive surface after perspective transformation. When such hardware is used, since the interpolation is performed using the depth values of the inverted vertices, the depth values of the interpolated pixels between the vertices are also inverted values. Therefore, by inverting only the constituent points of the primitive surface and performing the GREATER determination, the LESS is automatically interpolated for each pixel of the primitive surface.
It is possible to obtain the same result as the judgment.

Therefore, according to the present invention, the shadow area can be specified by utilizing the depth test function provided by the hardware even when the image is generated by using the hardware which cannot perform the LESS judgment only by the GREATER judgment. .

(6) The image generation system, program, and information storage medium according to the present invention use a polygon enlarged by a given enlargement process when a given primitive surface is formed as a polygon. And performing a process of generating a shadow image corresponding to a given primitive surface.

According to the present invention, since a shadow image can be generated by using a polygon which is originally enlarged, a shadow image larger than usual can be generated for each polygon. Therefore, since mapping is performed using a shadow image larger than usual for each polygon, it is possible to fill the gap between polygons that originally occurs.

Therefore, according to the present invention, a certain hardware has the property of not drawing the right side and the lower side of a polygon, thereby eliminating the problem that the undrawn parts of the right side and the lower side of a shadow image appear as gaps. can do.

(7) Further, the image generation system, program and information storage medium according to the present invention enlarge the polygon by shifting the apex of the polygon from the centroid of the polygon to a point enlarged by a given scale. Characterize.

(8) Further, in the image generating system, program and information storage medium according to the present invention, when a given primitive surface is configured as a polygon, a shadow image is formed depending on the direction of the polygon and the direction of the light beam of the light source. The feature is that a primitive surface that is a target of generation processing is determined, and a shadow image generation processing is performed only for the primitive surface that is a processing target.

The direction of the polygon can be specified by the direction of the normal vector, for example. The direction of the light ray is the direction of the light ray in the case of the parallel light source, and may be the direction connecting the light source and the polygon in the case of the point light source or the spot light source.

According to the present invention, it is possible to determine whether or not a given polygon is a polygon that completely shades, based on the direction of the polygon and the direction of the light beam of the light source.

For example, if the direction of the light ray of the light source and the direction of the normal of the polygon point in the same direction, it is determined that this polygon is a shadow.

When the direction of the light ray of the light source and the direction of the normal of the polygon point in opposite directions, it is determined that this polygon is not a shadow. However, since a shadow of an object forming the object space is generated in such a state, a shadow image generation process is performed in this case.

By performing such processing, the polygons to be processed can be narrowed down, so that the processing load can be reduced and the noise in the image can be reduced.

(9) Further, the image generation system, program and information storage medium according to the present invention are characterized in that the objects forming the object space are contained in a given bounding box.

By doing so, the depth data of the object space viewed from the light source can be drawn and accommodated within the predetermined buffer size.

[0057]

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

1. Configuration FIG. 1 shows an example of a block diagram of this embodiment. It should be noted that in the figure, this embodiment only needs to include at least the processing unit 100, and the other blocks can be arbitrary constituent elements.

Here, the processing section 100 performs various kinds of processing such as control of the entire system, instruction of instructions to each block in the system, game processing, image processing, sound processing, etc., and its functions are various. Processor (CPU, DSP
Etc.) or hardware such as ASIC (gate array etc.) or a given program (game program).

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

The storage unit 170 includes the processing unit 100 and the communication unit 1.
It is a work area such as 96, and the main memory 17
2. It functions as the frame buffer 174 (first frame buffer, second frame buffer) and can be realized by hardware such as RAM.

An information storage medium (storage medium usable by a computer) 180 stores information such as programs and data, and its function is that of an optical disc (C
D, DVD), magneto-optical disk (MO), magnetic disk, hard disk, magnetic tape, or memory (RO
It can be realized by hardware such as M). Processing unit 10
0 performs various processes of the present invention (this embodiment) based on the 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 (the present embodiment) (particularly the block included in the processing unit 100).

A part or all of the information stored in the information storage medium 180 is transferred to the storage section 170 when the system is powered on. The information storage medium 1
Information stored in 80 is a program code for performing the process of the present invention, image data, sound data, shape data of a display object, table data, list data, information for instructing the process of the present invention, and instructions thereof. The information includes at least one of the information for performing the processing according to the above.

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

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

The save information storage device 194 stores the player's personal data (save data) and the like. As the save information storage device 194, a memory card, a portable game device or the like may be considered. it can.

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

The program or data for executing the means of the present invention (this embodiment) is 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. You may Use of such an information storage medium of the host device (server) is also included in the scope of the present invention.

The processing section 100 includes a game processing section 110, an image generating section 130, and a sound generating section 150.

Here, the game processing unit 110 accepts coins (price), sets various modes, progresses the game, sets selection screens, and positions and rotation angles of objects (one or more primitive surfaces). (Process for obtaining (rotation angle around X, Y or Z axis), process for moving object (motion process), process for obtaining viewpoint position (position of virtual camera) and line-of-sight angle (rotation angle of virtual camera), map object Such as arranging objects in the object space, hit check processing, processing for calculating game results (results, achievements), processing for allowing multiple players to play in a common game space,
Alternatively, various game processing such as game over processing,
This is performed based on operation data from the operation unit 160, personal data from the save information storage device 194, a game program, and the like.

The image generating section 130 includes a game processing section 110.
Drawing for drawing various geometry processing (three-dimensional computation) such as coordinate transformation, clipping processing, perspective transformation, or light source calculation, or an object (model) after geometry processing in the frame buffer 174 according to instructions from Various types of image processing such as processing are performed to generate an image viewed from the virtual camera (viewpoint) in the object space and output to the display unit 190.

The image generating section 130 includes a self shadow processing section 140.

The self-shadow processing unit 140 obtains the depth data of the object space viewed from the light source in pixel units, and the shadow area cast by the object space on a given primitive surface forming the object space. A shadow image generation process for identifying a shadow image corresponding to a given primitive surface based on the shadow area, using the depth data of the space, and mapping the shadow image to the corresponding primitive surface, Performs processing to generate an image of the object space viewed from the viewpoint.

As the shadow image generation process, the depth value given in relation to the given primitive surface seen from the light source is compared with the depth value of the scene seen from the light source to the object space to give the given primitive surface seen from the light source. In the drawing area of, the area in which the light from the light source is blocked by the object existing in the object space is determined, and the shadow area cast by the object space on the given primitive surface is specified. Good.

The depth data of the object space viewed from the light source is the depth data of the scene that is perspective-projected or converted from the light source in the object space, and is the depth data of the given primitive surface after perspective conversion or projection conversion viewed from the light source. A depth test using a given determination method may be performed based on the depth values of the constituent points and the depth data of the object space viewed from the light source, and a shadow image corresponding to a given primitive surface may be generated.

Further, based on the coordinates of the constituent points of a given primitive surface after perspective transformation or projection transformation as seen from the light source, the texture coordinate coordinates for mapping the shadow image to the corresponding primitive surface are determined and the mapping processing is performed. May be performed.

As the shadow image generation processing, processing for inverting the depth values of the constituent points of a given primitive surface after perspective transformation or projection transformation, and inverting the Z buffer holding the depth data of the object space viewed from the light source. Z buffer reversal processing to be performed and drawing processing for a given primitive surface in which the depth values of the constituent points are reversed by using the Z buffer subjected to the Z buffer reversal processing by using a predetermined determination method of the depth test. May be performed.

When a given primitive surface is configured as a polygon, a given enlargement processing is performed to generate a shadow image corresponding to the given primitive surface using the enlarged polygon. You may For example, the polygon may be enlarged by shifting the vertex of the polygon from the center of gravity of the polygon to a point enlarged by a given scale.

When a given primitive surface is configured as a polygon, the primitive surface that is the target of the shadow image generation processing is determined based on the direction of the polygon and the direction of the light ray of the light source. Only the shadow image generation processing may be performed.

Further, the sound generator 150 is equivalent to the game processor 1
Perform various sound processing according to the instructions from 10.
Sounds such as GM, sound effects, and voice are generated, and the sound output unit 192 is generated.
Output to.

The game processor 110 and the image generator 1
All of the functions of the sound generation unit 150 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.

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

When a plurality of players play,
The game images and game sounds to be provided to the plurality of players may be generated using one terminal, or may be generated using a plurality of terminals connected by a network (transmission line, communication line) or the like. Good.

2. Features of this embodiment The features of this embodiment will be described with reference to the drawings.

FIG. 2 shows an example of an image which has been subjected to the self-shadowing process of this embodiment.

As shown in the figure, a cube object 210 is arranged on the plane of the object space, and a parallel light source 220 is set in the upper rear part of the cube object 210. Reference numeral 230 is a shadow generated by the self-shadowing process.

FIG. 3 is a diagram for explaining the work buffer of the VRAM used when performing the self-shadowing process.

When performing the self-shadowing process, the VRAM
You may make it secure the work buffer as shown in FIG. 3 above.

Frame Buffer (ODD) 240, Frame Buffe
The r (EVEN) 250 and the Z Buffer 260 are VRAM work buffers for drawing shadowed scenes.

The Work Effect Buffer 260 is a temporary work buffer for performing "LESS conversion of depth data" and a VRAM work buffer for generating a "shadow map" for each polygon. The Work Z Buffer 280 is a VRAM work buffer for temporarily storing “depth data” in which the entire scene of the object space viewed from the light source is drawn and storing “less depth data”.

Next, an example of processing for generating a shadow image using depth data will be described with reference to FIGS.

4A and 4B are depth data of the object space viewed from the light source (depth data of the entire scene).
It is a schematic diagram for explaining about.

Reference numeral 310 in FIG. 4A shows Work Z when the entire scene viewed from the light source is drawn in the Work Z Buffer.
It is the figure which represented the content of Buffer typically. 312 here
Is the whole scene depth data (depth data in the object space) viewed from the light source, and the depth value is indicated by the shade of color for the sake of explanation. That is, it indicates that the depth data (Z value) of the darker color is located closer to the light source. Here, the handling of the depth data about the plane itself on which the object is placed is omitted.

Reference numeral 320 in FIG. 4 (B) is an inversion of the contents of the entire scene depth data 322 in FIG. 4 (A). By this inversion, the Work Z Buffer is ready for the LESS determination from the next operation, and becomes a stencil for generating a shadow part for each polygon. The contents of this depth data are LESS-ized depth data (Z buffer depth data subjected to Z buffer inversion processing). Details of the depth data inverting method will be described later.

In this embodiment, the depth data of FIG. 4 (A) or the depth data of FIG. 4 (B) is used to correspond to each primitive surface for creating a shadow cast on each primitive surface by the object space. A shadow map can be generated.

FIGS. 5A to 5D are views for explaining the process of generating a shadow map corresponding to a given primitive surface forming the object space by using the depth data or the LESS-ized depth data. Is.

Here, a case where the primitive surface is composed of polygons will be described as an example.

First, as shown in FIG. 5A, Work Effect
Clear the contents of Buffer 330. Work Effect Buffer
A depth test is performed for each polygon on the depth data indicated by 310 in FIG. 4A or the LESS-ized depth data indicated by 320 in FIG. 4B, and the result is written in 330. Therefore, when performing the depth test, clear the contents of the Work Effect Buffer in advance. This operation is for the first polygon only. From the next polygon, the polygon used in the previous depth test is overwritten in the buffer with the clear (BG) color as shown in FIG. 5B. Good.

Further, with respect to each vertex coordinate of the polygon to be subjected to the depth test, the same projection conversion as when the depth data of the object space (depth data of the entire scene) viewed from the light source of FIGS. 4A and 4B is generated. Give.

Then, as shown in FIG. 5 (C), Work ZB
A depth test is performed on the depth data of the uffer 332 or the depth data converted into the LESS by a predetermined determination method for each polygon 340, and the result is a Work Effect Buff
draw on er.

In the depth test performed here, it is possible to determine the area where the light from the light source is blocked by another object in the drawing area of the polygon projected in parallel from the light source (area which becomes the shadow of the object existing in the object space). Must be one. That is, it is preferable that the depth test is capable of drawing a portion located deeper in the scene viewed from the light source.

For example, in the case of performing processing by hardware capable of LESS determination described later, by performing a depth test by LESS determination using depth data and vertex coordinates of polygons after projection conversion,
It is possible to draw a part located farther from the scene viewed from the light source.

When the depth test is performed in this way, the result is drawn in the Work Effect Buffer, and a shadow image as shown at 350 in FIG. 5D is generated. In this shadow image, a portion located deeper than the scene viewed from the light source is drawn. Then, a shadow map for each polygon is generated using this shadow image 350.

It is also possible to represent a shadow by a color light by matching the color (for example, the color of the shadow image 350 in FIG. 5D) when writing to the work effect buffer with the color of the light source.

Next, the polygon map viewed from the viewpoint coordinate system is drawn using the generated shadow map. FIG. 6 is for explaining how to draw the polygon in the frame buffer using the generated shadow map. FIG.

As shown in FIG. 6, when a polygon 370 perspectively transformed from the viewpoint is drawn in the frame buffer 360, a shadow map (350 in FIG. 5D) corresponding to the polygon is mapped. . This makes it possible to represent the shadow 380 that has fallen on the polygon 370.

Thus, a shadow map is generated for each polygon forming the object space as shown in FIGS. 5A to 5D, and the shadow map is used for each polygon forming the object space. By performing the processing described with reference to FIG. 6, the shadow cast on each polygon forming the object space can be expressed.

FIG. 7 is a completed view of the two polygons arranged in the object space as viewed from the viewpoint coordinate system. The figure shows a state in which a shadow is cast on the P2-1 area of the polygon P2 by the parallel light source directly above the two polygons P1 and P2 which are objects forming the object space.

FIGS. 8A and 8B show Work Z Buffer and Wor.
It is a schematic diagram for explaining the relationship between k Effect Buffer and Frame Buffer.

FIG. 8A shows Work Z Buffer 420-1 and Work Effect Buffer 430 in the process of drawing polygon P1.
-1, and the state of Frame Buffer 440-1 is shown.

The Work Z Buffer 420-1 shows the state of the depth data of the scene as viewed from the light source for the two polygons projected and converted from the light source direction. Z1 stores the depth data generated by the polygon P1, and Z2 stores the depth data generated by the polygon P2.

Then, a depth test is performed on the polygon P1 using the depth data of the Work Z Buffer 420-1, and a shadow map for the polygon P1 is generated in the Work Effect Buffer 430-1. Here, the polygon P1
Is on the most front side (on the light source side) with respect to the depth data of the scene viewed from the light source, so a shadow image is not drawn (430
-1). Therefore, the image of the polygon P1 without a shadow is drawn in the Frame Buffer 440-1.

FIG. 8B shows Work Z Buffer 420-2 and Work Effect Buffer 430 in the process of drawing polygon P2.
-2, the state of the Frame Buffer 440-2 is shown.

Work Z Buffer 420-2 is Work Z Buffer
It is similar to 420-1. The contents of Work Z Buffer is a stencil for performing the depth test of all polygons, so it is not updated by the depth test.

Work Effec in the state of 430-1
The t Buffer is once cleared, a depth test is performed on the polygon P2 using the depth data of the Work ZBuffer 420-2, and a shadow map for the polygon P1 is generated in the Work Effect Buffer (see 430-2). Here, since the area P2-1 (see FIG. 7) of the polygon P2 is deeper than the depth data of the scene as seen from the light source, the shadow image Z2 is generated. On the other hand, P2-2 of polygon P2
The area (see Fig. 7) is closest to the light source (light source side)
Therefore, the shadow image drawn in a portion located farther from the scene viewed from the light source is not drawn. In this way, the polygon P2 is stored in the Work Effect Buffer 430-2.
A shadow map corresponding to is generated.

Then, the polygon P2 viewed from the viewpoint coordinate system is
When drawing in the Frame Buffer 440-2, by mapping the shadow map as a texture,
An image of a polygon P2 with a shadow cast is drawn in the Buffer 440-2.

FIG. 9 is a diagram for explaining the projection mapping for attaching the shadow map to the object viewed from the viewpoint.

In order to attach the shadow map to the object viewed from the viewpoint, it is necessary to perform projection mapping for each polygon of the object viewed from the light source. That is, when performing a depth test for generating a shadow map, the vertex coordinates (XY) after polygon projection conversion is converted into ST coordinates and used as texture coordinate data.

For example, the vertex coordinates TV1, TV2, TV3 of the polygon P in the Work Effect Buffer 430 are held, and V1, V2, and V2 are used when texture mapping is performed using the Work Effect Buffer 430 as a texture, respectively.
It can be used as texture coordinate coordinates corresponding to V3.

3. Depth test The depth test is a method for determining a pixel to be drawn, such as a Z test. When a new polygon is to be drawn, the Z buffer of the previously drawn polygon and the Z of the polygon to be drawn are used. It is a test that compares the values pixel by pixel to determine the pixel to be drawn.

Here, the judgment method when performing the depth test is as follows:
This is a judgment method regarding the magnitude relationship between the Z values of the polygon drawn before and the polygon drawn from now on.
R determination, LESS determination, and the like are known.

FIGS. 10A and 10B are schematic diagrams for explaining the GREATER determination and the LESS determination.

For example, assuming that the Z value of the Z buffer is A and the Z value of the polygon to be drawn is B, the GREETER determination is that the Z value (A) of the polygon to be drawn is greater than the Z value (B) of the Z buffer. Judgment method for drawing (A>
B is a drawing success), and the LESS judgment is that the Z value (A) of the polygon to be drawn is the Z value (B) of the Z buffer.
The judgment method to draw when it is smaller (drawing is successful when A <B)
Is.

For simplicity of explanation, assume that the value of Z of all pixels in the current Z buffer is Zk. A polygon 500 in FIG. 10A is a polygon after perspective transformation, and is composed of three vertices V1, V2, and V3. The value of Z value of each vertex V1, V2, V3 is Z1, Z
2 and Z3. If Z3 <Zk <Z2 <Z1 at this time, 510 is the area selected by the GREETER determination (see FIG. 10A), and 520 is the LESS.
This is the area selected by the determination (see FIG. 10B).

When the hardware for performing the processing as described above supports the depth test by the LESS determination, the depth data is subjected to the LESS determination for each polygon in the processing of FIG. 5C. This makes it possible to generate a shadow map.

However, when processing is performed using hardware that supports the GREETER method but does not support the LESS method, the pseudo LE as described below is used.
Perform SS determination processing.

In order to generate the LESS-ized depth data as shown in FIG. 4B, a buffer (Work E) which is temporarily used in the VRAM when the contents of the Z buffer is inverted.
secure a ffect buffer).

Then, any depth data (Work Z Buffe
r) is treated as an RGB image, and 0xff, 0xff, 0xff, 0xff (RGB
The Work Effect Buffer cleared in A) is synthesized with an arbitrary α blending formula. This makes Work Effect Bu
It is possible to generate a negative image of the Work Z Buffer image on the ffer.
The RGB image is converted to depth data and copied to the Buffer) to create LESS depth data.

FIG. 11 is a schematic diagram for explaining a process for generating LESS-ized depth data.

First, set Work Effect Buffer 560 to 0xf in advance.
Clear with f, 0xff, 0xff, 0xff (RGBA).

Then, the contents (depth data) of Work Z Buffer 550 are used as textures, and Work Effect Buffer 56
Draw polygons in 0 area. In this operation, α blending is performed. Here, for example, when Cv = (A−B) × C >> 7 + D is used as the α blending equation, the coefficient of each of A, B, C, and D is represented by “A = C”.
“D”, “B = Cs”, “C = 0x80”, and “D = 0” are set. This allows Work E to maintain the 0xffffffff state.
By drawing a polygon in the ffect Buffer 560 while performing α blending considering the above formula,
An image (image data) with the Z buffer inverted is generated (see 560).

Then, the contents (image data) of the Work Effect Buffer 560 are used as a texture map material and Wo
Draw a polygon that fills the area of rk Z Buffer. At the time of this operation, the α blending process is performed. Here, “A = Cs”, “B = 0”, “C = 0x80”, “D =
By setting "0", Work Effect Buffer 560
The contents of can be copied to Work Z Buffer 570 as depth data.

FIG. 12 shows Work Z Buffe using α subtraction processing.
FIG. 9 is a schematic diagram for explaining a process of inverting the content of r.

Reference numeral 600 is a schematic representation of the state of the Work Z Buffer before conversion to LESS, 610 is the cleared Work Effect Buffer, and 610 'is the Work Effect Buffer after α subtraction processing. .

Z ₁ is Work Z Buffer before LESS conversion
600 pixels, P ₁ cleared Work Effe
It is a pixel on the ct Buffer 610 and corresponds to Z ₁ . Z ₁ 'is Work Effect after α subtraction
It is the pixel in the buffer that corresponds to Z ₁ .

In this embodiment, Work Z before conversion to LESS is performed.
Buffer 600 is regarded as a color information buffer (texture buffer), and the cleared Work Effect Buffer 61
Draw to 0 by alpha subtraction.

Here, Work Z Buffer 60 before LESS conversion
Considering 0 as a color information buffer is, for example, 632,63.
4, 636 and 638, 0 to 7 bits (638) of the Z value 630 of the pixel Z ₁ are regarded as the A value Za, and 8 to 15 bits (636) are regarded as the R value Zr. , 16 to 23 bits (634) are G values Zg
The value of G is 24 to 31 bits (632).
Means to consider g.

Work Effect Buffer 61 cleared
"0xff0xff0xff0xff" is set to the value of each pixel on 0 as shown by 642-648, and here, "0xff" of 0 to 7 bits (648).
Is the value of A, 8 to 15 bits (636) "0xf
f ”is the value of R, and is 0 to 15 to 23 bits (634).
“Xff” is the G value, and “0xff” up to 24-31 bits (632) is the B value.

Work Effect Buffer 61 after α subtraction processing
The value corresponding to Zb, Zg, Zr, and Za at 0'is set to Z.
a ', Zr', Zg ', Zb'(0xff> Za, 0x
ff> Zr, 0xff> Zg, 0xff> Zb), the following formula is given.

Za '= 0xff-Za (1) Zr' = 0xff-Zr (2) Zg '= 0xff-Zg (3) Zb' = 0xff-Zb (4) ) (1) to (4) are Za ', Zr', Zg 'and Zb' are Z
It is shown that they are the inverted values of a, Zr, Zg, and Zb. This indicates that the Z value 650 of pixel Z1 ′ is the inverted value of the Z value 630 of pixel Z1.

Note that the alpha subtraction processing of (1) to (4) may be performed using the semitransparent calculation function of the drawing processor, for example.

FIG. 13 is a diagram for explaining the process of inverting the Z value of the apex of a given polygon that has undergone projection conversion as seen from the light source.

Reference numeral 680 schematically shows the state of the polygon before the Z value of the vertex is inverted, and 680 'shows the state of the polygon after the Z value of the vertex is inverted. Is.

Each vertex V1, V2, V3 of the polygon 680
Corresponds to the vertices V1 ′ and V1 of the polygon 680 ′.
2 ', V3'. Here, each vertex V of the polygon 680
If Z values of 1, V2, and V3 are Z1, Z2, and Z3, and Z values of vertices V1 ′, V2 ′, and V3 ′ of the polygon 680 ′ are Z1 ′, Z2 ′, and Z3 ′, Z1 ′. , Z2 ',
Z3 'is given as follows.

Z1 '= 0xff-Z1 (5) Z2' = 0xff-Z2 (6) Z3 '= 0xff-Z3 (7) (5) to (7) are Z1', Z2 'and Z3' are Z1 and Z
2 and Z3 are shown as inverted values.

The inversion processing of (5) to (7) may be realized by, for example, the CPU (main processor) executing a program for the inversion processing.

FIGS. 14A and 14B are views for explaining the areas selected by the Z test at the time of drawing.

Here, FIG. 14A is a diagram schematically showing the areas selected by the LESS judgment of the Z test at the time of drawing, similarly to FIG. 10B. And FIG.
(B) is a GREETER determination method of Z test when performing drawing processing by using the depth data LESS-processed by performing the Z buffer inversion processing on a given polygon in which the Z value of the vertex is inverted. The area selected by is schematically shown.

Here, the polygon 700 is a polygon in which the Z value of the apex is inverted, and Z1 ', Z2' and Z3 'are the same as those in (5) to (3) above with respect to Z1, Z2 and Z3 in FIG.
It is given by using the equation (7).

Therefore, the direction of the Z axis 710 'in FIG. 14 (B) is opposite to the direction 710 of the Z axis in FIG. 14 (A).

Generally, when drawing a polygon,
Only the vertex coordinates (x, y, z) of the polygon are given to the drawing processor, and each pixel between the polygons (polygon 70
Vertex coordinates (x ', edge of 0 and each pixel inside)
y ', z') is calculated by interpolation. Here, since z is an inverted value, the value of z ′ interpolated based on this is also obtained as an inverted value. That is, FIG.
The ridge line of the polygon 700 in (B) and the Z value of each internal pixel are inverted values.

Therefore, if the GREATER judgment of the Z test is performed with respect to the reference value Zk, the shaded area 720 '(the area selected by the pseudo LESS judgment) in FIG. 14B is selected. This is LES as shown in FIG.
It matches the area selected by S judgment.

As described above, in this embodiment, the Z test G
An area 720 ′ similar to the area 520 selected by the LESS determination can be selected using the result of the REATER determination.

4. Processing of this Embodiment FIG. 15 is a flow chart for explaining an example of the self-shadowing processing of this embodiment.

First, the whole scene viewed from the light source is Work Zbu
draw on ffer. (Step S10).

Here, the scene may be set using the bounding box. That is, in order to perform self shadow of all objects,
All objects in the scene need to draw and fit within the buffer size. Therefore, the bounding box of the entire object may be obtained, and the parallel projection conversion by the parallel light source may be operated so that the object fits in the entire screen.

Next, the contents of Work Z Buffer are changed to Work Effect B
It is converted into the inverted data by using the uffer (step S20). For example, the processing described with reference to FIGS. 11 and 12 is performed to generate LESS depth data.

Next, the Work Effect Buffer is cleared.
(Step S30) Next, an index variable I for counting polygons is initialized (step S4).
0).

Next, the processes from steps S50 to S100 are performed until the processes are completed for all the polygons.

First, the index variable I is incremented (step S50).

Next, when I ≧ 2, the polygon (I-
1) to 0xff, 0xff, 0xff, 0xff (RG
Draw with (BA) (step S60). As a result, the drawing target area of the polygon for which the depth test was performed last time can be cleared regardless of whether or not there is drawing.

Next, each vertex of the polygon (I) after projection conversion in the ray direction is obtained, and the Z value is subtracted from 0xffffff and substituted into each element (XYZ) of the array V (step S70).

Next, a polygon is drawn on the Work Z Buffer using the array V by the depth test of the GREATER method (step S80). Pixels that were true by the depth test will be written to the Work Effect Buffer. As a result, a shadow map for the polygon as described with reference to FIG. 5D is generated.

Next, using the data written in the Work Effect Buffer as a texture map of the polygon (I), the polygon (I) is drawn in the frame buffer in the visual field coordinate system seen from the viewpoint. (Step S90).

If I ≧ the number of polygons, the process ends (step S100).

5. Polygon Enlargement Processing FIGS. 16 (A) and 16 (B) are diagrams for explaining problems that occur when the self-shadowing processing is performed using a certain type of hardware.

Originally, an image as shown in FIG. 16 (A) should be generated, but if self-shadow processing is performed using some kind of hardware, an image as shown in FIG. 16 (B) is generated. There was a problem that it would end up. That is, when self-shadow processing is performed using a certain kind of hardware, a gap 750-1 is formed at the boundary between polygons in the shadow image.
˜750-8 may occur.

As a result of investigating the cause, it has been found that a certain kind of hardware has a property of not drawing the right side and the lower side of the polygon, so that the undrawn parts of the right side and the lower side appear as gaps.

17A and 17B are diagrams for explaining the polygon enlargement processing (Fat processing).

FIG. 17A is a diagram showing a case where a shadow map 766 is generated by performing the depth test described with reference to FIG. 5C using a normal polygon 760.

On the other hand, FIG. 17B shows a polygon 762 that is thicker (enlarged) than the normal polygon 760.
Is set, and the thickened (enlarged) polygon 762 is set.
FIG. 6 is a diagram showing a case where a shadow map 764 is generated by performing the depth test described with reference to FIG. FIG. 17 (B)
The shadow map 764 generated by the method of FIG.
Compared to the shadow map 766 generated by the method (A), it has a larger area (the thick shadow map 7
64).

In this embodiment, since projection mapping is performed using the thick shadow map 764 generated by the method of FIG. 17B, it is possible to fill the gap between polygons that originally occurs.

FIG. 18 is a diagram for explaining a specific example of polygon enlargement processing.

The vertices of a normal polygon 762 are V1, V
2 and V3, with respect to the center of gravity G of a normal polygon,
New V1 ', V2', and V3 'are set to the points obtained by enlarging each of the vertices V1, V2, and V3 by a predetermined scale, and set as the vertices of the thickened (enlarged) polygon 762.

FIGS. 19A and 19B are views for explaining the processing for selecting polygons which are not the object of self-shadowing processing.

In the present embodiment, a process for determining whether or not the polygon is a shadow completely by considering the light source and the vector according to the direction of the light source and the normal vector of each polygon in advance.

When the direction of the light source 780 and the direction of the normal line 790 of the polygon 770 point in the same direction as shown in FIG. 19A, it is determined that the polygon 770 is a shadow. That is, since the surface on which the normal line of the polygon is formed is the surface of the polygon, it is determined that the polygon 770 itself is a full shadow.

In addition, as shown in FIG.
When 82 and the direction 792 of the normal line of the polygon point to the winning combination direction, it is determined that the polygon 772 is not a shadow. However, since the shadow of the self shadow due to the scene in the object space is generated in such a state, the self shadow processing is performed only at this determination.

By performing such processing, it is possible to reduce the processing addition accompanying the self-shadow processing and reduce the noise of the image.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

FIG. 21A shows an example in which this embodiment is applied to an arcade game system. The player enjoys the game by operating the lever 1102, the buttons 1104, etc. while watching the game image displayed on the display 1100. Various processors, various memories, etc. are mounted on the built-in system board (circuit board) 1106. Information (program or data) for executing each unit of the present invention is stored in the memory 1108 which is an information storage medium on the system board 1106. Hereinafter, this information will be referred to as stored information.

FIG. 21B shows an example in which this embodiment is applied to a home game system. While watching the game image displayed on the display 1200, the player operates the game controllers 1202 and 1204 to enjoy the game. In this case, the above-mentioned stored information is stored in the CD 1206 or the memory cards 1208, 1209, which is an information storage medium that can be detachably attached to the main body system.

FIG. 21C shows a host device 1300,
This host device 1300 and network 1302 (LA
A terminal 130 connected via a small network such as N or a wide area network such as the Internet)
An example in which the present embodiment is applied to a system including 4-1 to 1304-n will be described. In this case, the stored information is, for example, a magnetic disk device that can be controlled by the host device 1300,
It is stored in an information storage medium 1306 such as a magnetic tape device or a memory. When the terminals 1304-1 to 1304-n are capable of standalone generation of game images and game sounds, the host device 1300 sends game images,
A game program or the like for generating a game sound is provided on the terminal 1
It is delivered to 304-1 to 1304-n. On the other hand, when it cannot be generated standalone, the host device 1300 generates a game image and a game sound, and the terminal device 1304-1 ...
It will be transmitted to 1304-n and output at the terminal.

In the case of the configuration of FIG. 21C, each means of the present invention may be distributed and executed by the host device (server) and the terminal. Further, the above stored 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.

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

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

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

In the present embodiment, the case where the light source is a parallel light source when the scene viewed from the light source is generated and the projection conversion is performed in the light ray direction from the light source has been described as an example, but the present invention is not limited to this. For example, when the light source is a point light source or a spot light source, perspective transformation may be performed with the light source as the viewpoint.

In the present embodiment, the case where the Z buffer inversion process is realized by performing the drawing process using the alpha subtraction process has been described as an example, but the present invention is not limited to this. For example, the Z value of the Z buffer may be inverted by another method.

Further, in the present embodiment, the names LESS judgment and GREATER judgment are used as the Z test judgment method, but different judgment names may be used as long as the same functions are realized.

Further, in this embodiment, the closer to the viewpoint, the Z
The case has been described as an example in which the Z value decreases as the value increases and the distance from the viewpoint increases, but the present invention is not limited to this. For example, the Z value may be smaller as it is closer to the viewpoint, and may be larger as it is farther from the viewpoint.

Further, the present invention can be applied to various game systems such as an arcade 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 a game image. .

[Brief description of drawings]

FIG. 1 is an example of a block diagram of the present embodiment.

FIG. 2 is an example of an image subjected to self-shadowing according to the present embodiment.

FIG. 3 is a VRA used when performing a self-shadowing process.
It is a figure for demonstrating the work buffer of M.

4A and 4B are diagrams for explaining depth data of an object space viewed from a light source (depth data of an entire scene).

5 (A) to (D) are depth data or L. FIG.
It is a figure for demonstrating the process which produces | generates the shadow map corresponding to the given primitive surface which comprises an object space using the ESS-ized depth data (depth information).

FIG. 6 is a diagram for explaining how to draw a polygon in a frame buffer using the generated shadow map.

FIG. 7 is a completed view of two polygons arranged in an object space as viewed from a viewpoint coordinate system.

8A and 8B show Work Z Buffer and Work Ef.
It is a schematic diagram for explaining the relationship between fect buffer and frame buffer.

FIG. 9 is a diagram illustrating projection mapping for attaching a shadow map to an object viewed from a viewpoint.

10A and 10B are schematic diagrams for explaining a GREATER determination and a LESS determination.

FIG. 11 is a schematic diagram for explaining a process of generating LESS-ized depth data.

FIG. 12 is a schematic diagram for explaining a process of inverting the contents of Work Z Buffer using α subtraction processing.

FIG. 13 is a diagram for explaining a process of inverting the Z value of the apex of a given polygon that has undergone projection conversion as seen from the light source.

14A and 14B are diagrams for explaining an area selected by a Z test at the time of drawing.

FIG. 15 is a flowchart for explaining an example of self-shadowing processing according to the present embodiment.

16 (A) and 16 (B) are views for explaining a problem that occurs when self-shadow processing is performed using a certain type of hardware.

17A and 17B are diagrams for explaining the Fat process for polygons.

FIG. 18 is a diagram for explaining a specific example of polygon enlargement processing according to the present embodiment.

19A and 19B are diagrams for explaining a process of selecting polygons that are not the target of the self-shadowing process.

FIG. 20 is a diagram for explaining an example of a hardware configuration of the present embodiment.

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

FIG. 22 is a diagram for explaining a shadow texture generated when performing a shadow map.

FIG. 23 is a diagram for explaining a case where a shadow of a chair object is added to a floor wall object by a shadow map method.

FIG. 24 is a diagram showing a state in which a shadow of an object is added to oneself using a shadow map method.

[Explanation of symbols]

100 processing unit 110 Game processing unit 130 Image generator 140 Self-shadow processing section 160 Operation part 170 storage 172 main memory 174 frame buffer 180 Information storage medium 190 Display 192 sound output section 194 Information storage device for saving 196 Communications Department

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C001 BA03 BA05 BA06 BC05 BC08                       CA02 CB01 CB02 CB04 CB06                       CB08 CC01 CC08 DA04                 5B050 BA09 BA18 EA12 EA28 EA30                       FA02                 5B080 AA13 BA04 BA07 CA01 CA05                       CA07 GA02 GA22

Claims (20)

[Claims] 1. A system for generating an image, comprising means for obtaining depth data of an object space as seen from a light source in pixel units, and a shadow area cast by the object space on a given primitive surface forming the object space. Shadow image generation processing means for generating a shadow image corresponding to a given primitive surface based on the shadow area, which is specified by using depth data of the object space viewed from the light source, and the shadow image is mapped to the corresponding primitive surface. And a means for performing a process for generating an image of the object space viewed from a given viewpoint, and an image generation system characterized by the following. 2. The shadow image generation processing means according to claim 1, wherein the depth value given in relation to a given primitive surface viewed from the light source is compared with the depth value of the scene viewed from the light source to the object space, and the light source is compared. In the drawing area of the given primitive surface viewed, the area in which the light from the light source is blocked by the object existing in the object space is determined, and the shadow area cast by the object space on the given primitive surface is specified. An image generation system characterized by performing a process. 3. The depth data of the object space as seen from the light source according to claim 1, is the depth data of a scene perspectively or projectively transformed from the light source of the object space. A shadow image corresponding to a given primitive surface is subjected to a depth test using a given judgment method based on the depth values of the constituent points of the given primitive surface after projection conversion and the depth data of the object space viewed from the light source. An image generation system characterized by generating. 4. The shadow image according to any one of claims 1 to 3, wherein the shadow image is mapped to a corresponding primitive surface based on the coordinates of the constituent points of a given primitive surface after perspective transformation or projection transformation viewed from the light source. An image generation system characterized by performing texture mapping processing by determining texture coordinate coordinates. 5. The shadow image generation processing means according to claim 1, wherein the shadow image generation processing means performs processing of inverting the depth value of a constituent point of a given primitive surface after perspective transformation or projection transformation, Z buffer inversion processing means for inverting the Z buffer holding the depth data of the object space viewed from the light source, and Z buffer subjected to the Z buffer inversion processing for a given primitive surface in which the depth values of constituent points are inverted. And a means for performing a drawing process by using a predetermined determination method of the depth test. 6. The polygon according to any one of claims 1 to 5, wherein when a given primitive surface is configured as a polygon, the given primitive surface is added to the given primitive surface by using the polygon enlarged by a given enlargement process. An image generation system characterized by performing a process of generating a corresponding shadow image. 7. The image generation system according to claim 6, wherein the polygon is enlarged by shifting the vertex of the polygon from a center of gravity of the polygon to a point enlarged by a given scale. 8. The method according to claim 1, wherein when a given primitive surface is configured as a polygon, depending on the direction of the polygon and the direction of the ray of the light source,
Determine the primitive surface that is the target of shadow image generation processing,
An image generation system characterized by performing a shadow image generation process only on a primitive surface to be processed. 9. The image generation system according to claim 1, wherein the objects forming the object space are configured to fit in a given bounding box. 10. A computer-executable program for obtaining depth data of an object space viewed from a light source in pixel units, and a shadow area cast by the object space on a given primitive surface forming the object space. , Shadow image generation processing means for generating a shadow image corresponding to a given primitive surface based on the shadow area, which is specified using the depth data of the object space viewed from the light source, and the shadow image to the corresponding primitive surface. A program for causing a computer to realize means for performing a process of performing mapping to generate an image of an object space viewed from a given viewpoint. 11. The given primitive surface viewed from the light source according to claim 10, wherein the depth value given in relation to the given primitive surface viewed from the light source is compared with the depth value of the scene viewed from the light source to the object space. Among the drawing areas of, the area in which the light from the light source is blocked by the object existing in the object space is determined, and the shadow area cast by the object space on the given primitive surface is specified. And the program. 12. The depth data of an object space as viewed from a light source according to claim 10, wherein the depth data of a scene is a perspective view or a projection conversion of the object space viewed from the light source, and the perspective data is A shadow image corresponding to a given primitive surface is subjected to a depth test using a given judgment method based on the depth values of the constituent points of the given primitive surface after projection conversion and the depth data of the object space viewed from the light source. A program characterized by generating. 13. The shadow image according to claim 10, wherein the shadow image is mapped to a corresponding primitive surface based on coordinates of constituent points of a given primitive surface after perspective transformation or projection transformation viewed from a light source. A program characterized by determining texture coordinate coordinates at the time and performing mapping processing. 14. The shadow image generation processing means according to claim 10, wherein the shadow image generation processing means is means for inverting the depth values of the constituent points of a given primitive surface after perspective transformation or projection transformation, Z buffer inversion processing means for inverting the Z buffer holding the depth data of the object space viewed from the light source, and Z buffer subjected to the Z buffer inversion processing for a given primitive surface in which the depth values of constituent points are inverted. A program for causing a computer to realize a means for performing a drawing process using a predetermined determination method of a depth test by using the computer. 15. The polygon according to claim 10, wherein, when a given primitive surface is configured as a polygon, a polygon enlarged by a given enlargement process is used to form a given primitive surface. A program that performs a process of generating a corresponding shadow image. 16. The program according to claim 15, wherein the polygon is enlarged by shifting a vertex of the polygon from a center of gravity of the polygon to a point enlarged by a given scale. 17. The method according to claim 10, wherein when a given primitive surface is configured as a polygon, depending on the direction of the polygon and the direction of the ray of the light source,
Determine the primitive surface that is the target of shadow image generation processing,
A program characterized by performing a shadow image generation process only on a primitive surface to be processed. 18. A program according to any one of claims 10 to 17, characterized in that an object forming an object space is contained in a given bounding box. 19. An information storage medium readable by a computer, comprising the program according to any one of claims 10 to 18. 20. A method of generating an image, comprising the steps of obtaining depth data of an object space viewed from a light source in pixel units, and a shadow area cast by the object space on a given primitive surface forming the object space. Identifying using the depth data of the object space viewed from the light source, generating a shadow image corresponding to a given primitive surface based on the shadow area, and mapping the shadow image to the corresponding primitive surface, An image generation method comprising: a process of generating an image of an object space viewed from a given viewpoint.