JP2009140135A - Game program, recording medium with the game program recorded thereon, and computer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display overlapped shadows of an object without causing any incompatibility. <P>SOLUTION: A two-dimensional image is created on a frame buffer by using luminance data of a static object B, the shadow BS and a dynamic object C, and whether to plot a shadow CS of the dynamic object C is determined based on the position relation of light L and the dynamic object C for every pixel of the created two-dimensional image, and whether or not the shadow of the static object B exists is determined based on the luminance data of the shadow of the static object B for the pixel where it is determined that the shadow CS of the dynamic object C should be plotted, and the luminance data of the shadow CS of the dynamic object C are set based on the decision result. Then, the shadow CS of the dynamic object C is plotted based on the set luminance data of the shadow CS of the dynamic object C for the pixel where it is determined that the shadow CS of the dynamic object C of the frame buffer should be plotted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a game program applied to a game device for converting an object arranged in a three-dimensional virtual space onto a screen image to convert it into a two-dimensional image and displaying it on a monitor, and recording the game program The present invention relates to a recording medium and a computer.

  2. Description of the Related Art Conventionally, there is known a game apparatus that displays a game development using video using three-dimensional computer graphics (hereinafter referred to as “three-dimensional computer graphics”). When creating a three-dimensional CG image used in this type of game device, so-called rendering is performed in which information about an object (for example, an object or a figure) given as digitized data is generated as a two-dimensional image by calculation. Processing is used (for example, see Patent Document 1).

JP-A-9-153142

  In the rendering process, when creating a two-dimensional image, image data of an opaque object that does not move and becomes a background of the game screen, such as a building, and the shadow of the object (hereinafter referred to as “static shadow”). Image data and the like are written into the frame buffer. The frame buffer is a memory that records a digital image as a two-dimensional image as a collection of pixels. In the rendering process, for example, image data of characters appearing in the game is also written in the frame buffer.

  On the other hand, a shadow that moves or changes its shape (hereinafter referred to as “dynamic shadow”) such as a shadow of a character is blended (synthesized) with the image data of the object as an overlap image. Written to the frame buffer.

  In various scenes on the game, the static shadow and the dynamic shadow may overlap. That is, for example, as shown in FIG. 11, there is a building B irradiated with light from the light L, and the character C moves to a shadow (static shadow) BS portion of the building B caused by the light L. Assuming that the shadow BS of the building B overlaps with the shadow (dynamic shadow) CS of the character C.

  In this case, when the image data of the dynamic shadow CS is synthesized with the image data of the static shadow BS on the frame buffer, the overlapping portion of the static shadow BS and the dynamic shadow CS becomes visually dark, That is, the luminance of the portion may be lowered and displayed unnaturally. In particular, for example, when the static shadow BS and the dynamic shadow CS having substantially the same hue and the same brightness overlap, the overlapping portion becomes visually dark.

  Here, it is assumed that the lowest luminance value “0” is white and the highest luminance value “1” is black. For example, the luminance values of the static shadow BS and the dynamic shadow CS are assumed to be “0.5”. In this case, the sum of the luminance values of the static shadow BS and the dynamic shadow CS is “0.5 + 0.5” and becomes “1”. In other words, the overlapping portion between the static shadow BS and the dynamic shadow CS becomes almost black, which may give an unnatural impression to the player.

  In particular, in recent game devices, drawing processing has been improved and it has become possible to express more realistic images. Therefore, video parts that give such an unnatural impression are compared to other video parts. This will make it more noticeable and give the player a sense of incongruity.

  The invention of the present application has been conceived under the circumstances described above, and includes a game program capable of displaying a portion where shadows of objects overlap each other without a sense of incongruity, a recording medium storing the game program, and a computer. The issue is to provide.

  In order to solve the above problems, the present invention takes the following technical means.

  In the game program provided by the first aspect of the present invention, a computer is operably disposed in one or more static objects that are fixedly disposed in a three-dimensional virtual space and the virtual space. A game program for creating a two-dimensional image in which one or more dynamic objects are projected from a predetermined viewpoint, and causing the computer to function as a game device for displaying on a display screen. Image creating means for creating the two-dimensional image on the frame buffer using brightness data of the static object, brightness data of the shadow thereof, and brightness data of the dynamic object for each frame; and For the two-dimensional image on the frame buffer created by the above, the position of a predetermined light source and a dynamic object for each pixel. A first determination unit that determines whether or not to draw a shadow of the dynamic object based on a relationship; and a pixel that is determined by the first determination unit to draw a shadow of the dynamic object, A second discriminating unit that discriminates whether or not a shadow of the static object exists based on luminance data of the shadow of the static object; and the dynamic unit based on a discrimination result by the second discriminating unit. A shadow data setting means for setting brightness data of a shadow of a simple object, and the dynamic object of the dynamic object set by the shadow data setting means with respect to a pixel in which the shadow of the dynamic object in the frame buffer is to be drawn. It is characterized by functioning as a drawing means for drawing a shadow of the dynamic object based on shadow luminance data.

  According to this game program, for each pixel of the frame buffer, a two-dimensional image is created on the frame buffer using the luminance data of the static object, the luminance data of the shadow thereof, and the luminance data of the dynamic object. . In this case, for each pixel on the frame buffer, whether or not to draw a dynamic object shadow is determined based on the positional relationship between a predetermined light source and the dynamic object, and the dynamic object shadow is drawn. It is determined whether or not there is a static object shadow based on the luminance data of the static object shadow, in other words, the dynamic object shadow and the static It is determined whether or not the shadow of the correct object overlaps. For example, when the shadow of a dynamic object and the shadow of a static object overlap, the luminance data of the shadow of the dynamic object is set to an appropriate value. Then, the shadow of the dynamic object is appropriately drawn based on the set luminance data of the shadow of the dynamic object with respect to the pixel in which the shadow of the dynamic object of the frame buffer is to be drawn.

  According to a preferred embodiment, in the pixel determined by the first determination means that the shadow of the dynamic object is drawn, the luminance data of the static object shadow and the pixel Functioning as addition means for adding the predetermined shadow luminance data of the dynamic object in the second object, and the second determination means uses the addition means instead of the static luminance data of the shadow of the object. It is preferable to determine whether or not there is a shadow of the static object based on a comparison result obtained by comparing the added data with a predetermined threshold (claim 2).

  According to another preferred embodiment, the second determination means determines that a shadow of the static object exists when the addition data is greater than the predetermined threshold, and the addition data is the predetermined data. The shadow object setting means determines that the shadow of the static object does not exist, and the shadow data setting means determines that the shadow of the static object exists by the second determination means, A subtraction value between the shadow brightness data of the static object and the shadow brightness data of the dynamic object is set as the brightness data of the shadow of the dynamic object, and the static data is set by the second determination unit. When it is determined that the shadow of the object does not exist, the dynamic brightness data of the shadow of the object may be set.

  According to another preferred embodiment, the luminance data of the shadow of the static object is included in a light map stored in advance in the storage means, and the addition means As the brightness data, brightness data corresponding to a pixel determined to have a shadow of the dynamic object drawn by the first determining means may be read from the light map and used.

  According to another preferred embodiment, the adding means includes correction value giving means for giving a correction value to the shadow brightness data of the static object and the shadow brightness data of the dynamic object. (Claim 5).

  The storage medium provided by the second aspect of the present invention is readable by a computer recording the game program provided by the first aspect of the present invention (claim 6).

  The computer provided by the third aspect of the present invention is characterized by executing the game program provided by the first aspect of the present invention (Claim 7).

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  According to the present invention, the dynamic object shadow is appropriately drawn based on the set luminance data of the dynamic object shadow for the pixel in the frame buffer where the dynamic object shadow should be drawn. Therefore, it is possible to display the portion where the shadow of the static object and the shadow of the dynamic object overlap with each other with a natural description.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing an example of a game apparatus to which a game program according to the present invention is applied. The game apparatus 1 is a television game machine used for home use, and the game program and game data are stored in a memory (RAM) in the apparatus from a DVD-ROM (Digital Versatile Disc-ROM) in which the game program and game data are recorded. And the game program is executed by the CPU so that the player can enjoy the game contents.

  Although the game apparatus 1 is a home video game machine as an example, the game apparatus 1 is not limited to a home video game machine, but may be other types such as a portable game machine and an arcade game machine. It may be a game machine or a device that displays 3D video other than the game machine, such as a personal computer loaded with a game program.

  The game apparatus 1 includes a CPU 2, a drawing data generation processor 3, a RAM 4, a ROM 5, a drawing processor 6, a VRAM (Video-RAM) 7, a D / A (Digital-Analog) converter 8, a sound processor 9, an amplifier 10, and an interface. (I / F) 11, a DVD-ROM drive 12, and a bus 13.

  The game apparatus 1 is usually connected to a television apparatus (not shown) for displaying game contents. A display device such as a cathode ray tube or a liquid crystal display of the television device is used as a monitor 14 externally connected to the D / A converter 8. The television apparatus is provided with a built-in speaker, and this built-in speaker is used as a speaker 15 externally connected to the amplifier 10.

  In the game apparatus 1, a DVD-ROM 17 in which a game program and game data are recorded is mounted on the DVD-ROM drive 12, the game program and game data in the DVD-ROM 17 are read into the RAM 4 by the DVD-ROM drive 12, and the CPU 2. By executing the game program, the player can enjoy the game contents.

  The game program describes processing procedures and various instructions to be executed by the CPU 2, and includes contents for controlling the game screen, sound, and the like according to operation signals from the operation controller 16. include. In this embodiment, in the game program, when shadows of a plurality of objects (for example, a building drawn on the game screen or a character appearing on the game) overlap each other in the two-dimensional video image, the rendering process unique to the present application causes a sense of incongruity. Includes a program that allows more natural shadows to be displayed.

  The game data includes image data of characters and buildings, image data for displaying information such as status, sound data such as sound effects and BGM, message data using characters and symbols, and the like.

  An operation controller 16 is connected to the game apparatus 1 via an interface (I / F) 11, and the player can advance the game by operating an operation member of the operation controller 16.

  The CPU 2, the drawing data generation processor 3, the RAM 4, the ROM 5, the drawing processing processor 6, the sound processing processor 9, the interface (I / F) 11, and the DVD-ROM drive 12 are connected to each other via a bus 13 so that data transmission is possible. .

  As described above, the CPU 2 executes the game program read from the DVD-ROM 17 to the RAM 4 by the DVD-ROM drive 12, thereby controlling the game progress in an integrated manner. More specifically, when an operation signal from the player is input from the operation controller 16, the CPU 2 performs a predetermined game progress process for the operation signal in accordance with the game program.

  For example, the CPU 2 determines the content of the 3D video to be displayed on the monitor 14, causes the drawing data generation processor 3 to generate drawing data necessary for the content, and transfers the drawing data to the drawing processor 6. Drawing processing is performed, and the drawing processing result is displayed on the monitor 14 as a three-dimensional image. Further, the CPU 2 determines sound contents such as sound effects or BGM to be output from the speaker 15, causes the sound processor 9 to generate sound data corresponding to the sound contents, and outputs the sound data from the speaker 15.

  The drawing data generation processor 3 performs various arithmetic processes necessary for the drawing process. The CPU 2 determines an image to be displayed on the monitor 14, and polygon data and texture data of image data (character, background, and other objects (hereinafter referred to as “object”) necessary for drawing the image. , And light source data) are read from the RAM 4 and supplied to the drawing data generation processor 3, the drawing data generation processor 3 performs data necessary for drawing (in perspective projection) based on the image data and operation information supplied from the CPU 2. The virtual camera, the positional relationship of each object, the coordinates of the polygons that make up each object on the screen, the texture corresponding to each polygon, and the reflection characteristics of each polygon, etc.) 6 is supplied. In the drawing processor 6, a 3D video drawing process for display on the monitor 14 is performed based on the calculation data supplied from the drawing data generation processor 3.

  The RAM 4 provides an area (not shown) for storing a game program and game data read from the DVD-ROM 17 by the DVD-ROM drive 12 and a work area (not shown) for the CPU 2 to process the game program. To do. In the RAM 4, game programs and game data necessary for the progress of the game are read from the DVD-ROM 17 and stored.

  The ROM 5 stores basic functions of the game apparatus 1 such as a disk loading function, and a basic program indicating a procedure for reading a game program and game data stored in the DVD-ROM 17. When the DVD-ROM 17 is loaded in the DVD-ROM drive 12, the CPU 2 operates the DVD-ROM drive 12 according to the basic program in the ROM 5, reads the game program and game data from the DVD-ROM 17 into the RAM 4, and starts the game. Set to.

  The drawing processor 6 generates an image of each frame of the 3D video (for example, a 2D image by a perspective projection method) and displays it on the monitor 14. The drawing processor 6 uses the data supplied from the drawing data generation processor 3 based on the drawing command from the CPU 2 to create a two-dimensional image of each frame to be displayed on the monitor 14 by a predetermined rendering process.

  Connected to the drawing processor 6 is a VRAM 7 for creating a two-dimensional image of each frame. The drawing processor 6 uses the VRAM 7 to generate 2D image data of each frame, for example, every 1/30 seconds.

  In the VRAM 7, a buffer memory 72 (hereinafter referred to as “frame buffer”) for storing two-dimensional image data of each frame displayed on the monitor 14 and image data to be stored in the frame buffer 72 are created. A buffer memory 71 (hereinafter referred to as “texture buffer”) for performing preprocessing is provided. The frame buffer 72 includes two frame buffers 72A and 72B having the same memory structure and memory capacity.

  Since the two frame buffers 72A and 72B are provided in the VRAM 7, it is possible to smoothly perform drawing processing of each frame on the monitor 14 every 1/30 seconds, for example. That is, while the display process on the monitor 14 is performed using one frame buffer 72A, the image data of the next frame is generated by the other frame buffer 72B, and this process is performed by the frame buffer 72A and the frame buffer 72B. By alternately performing between the two, the drawing process is performed smoothly.

  As will be described later, the VRAM 7 is provided with an area for storing a light map, a shadow map, a Z buffer, drawing data of each object, and the like.

  The D / A converter 8 converts the image data output from the frame buffer 72 into an analog signal and outputs the analog signal to the monitor 14. The D / A converter 8 is provided with a switch circuit for switching between the image data from the frame buffer 72A and the image data from the frame buffer 72B, and the switching of the switch circuit is controlled by the drawing processor 6.

  That is, when the drawing processor 6 uses the frame buffer 72A as the buffer of the monitor 14, the switching circuit is switched so that the image data of the frame buffer 72A is output to the monitor 14, and the frame buffer 72B is used as the buffer of the monitor 14. When switching, the switch circuit is switched so that the image data in the frame buffer 72B is output to the monitor 14.

  The sound processor 9 reads sound data such as sound effects or BGM from the RAM 4 based on a sound command from the CPU 2, performs a required processing process and D / A conversion process, and then outputs them to the amplifier 10. The amplifier 10 amplifies the audio signal input from the audio processor 9 with a predetermined amplification degree, and then outputs it to the speaker 15.

  The interface (I / F) 11 is an interface for connecting the operation controller 16 to the game apparatus 1. The operation controller 16 is for inputting various types of operation information to the game apparatus 1. The operation controller 16 is provided with a plurality of operation members (all not shown) such as a cross key, a left button, a right button, a select button, a start button, and a joystick.

  The start button is a button for inputting a game start, and the select button is a button for selecting menu contents. The joystick and the cross key are mainly used as operation members for instructing the character to perform various actions such as movement, attack and defense. The left button and the right button are used, for example, to move or rotate the line-of-sight direction of a 3D video image displayed on the monitor in the left direction or the right direction.

  As described above, in the game program according to the present embodiment, when shadows of a plurality of objects (for example, characters and buildings) overlap in a two-dimensional image, a more natural shadow without a sense of incongruity is rendered by a rendering process unique to the present application. It is intended to be displayed. Details will be described below.

  Next, the rendering process according to the present embodiment will be described. FIG. 2 is a flowchart showing a schematic procedure of the rendering process. The rendering process shown in this flowchart is mainly performed by the drawing processor 6. As shown in FIG. 2, the rendering process includes an object drawing process (S1), an overlap process (S2), an effect addition process (S3), and the like. The overlap process (S2) includes a cast process (S4), a receive process (S5), and the like.

  The object drawing process (S1) is a process for generating a two-dimensional image in the frame buffer 72 for an object that is normally composed of a plurality of polygons that are triangles. In the object drawing process of this embodiment, a drawing process for an opaque object such as a building is first performed. Thereafter, a drawing process of a translucent object such as water in the glass is performed, but the drawing process of the translucent object is a general process unrelated to the present invention, and thus the description thereof is omitted. The object drawing process described below is for an opaque object.

  In the object drawing process (S1), perspective projection and hidden surface removal are performed. Perspective projection refers to processing performed to display a three-dimensional virtual space on a two-dimensional monitor screen. Specifically, as shown in FIG. 3, for example, a viewpoint V corresponding to a camera (not shown) is placed at a predetermined position in a three-dimensional virtual space (in a space represented by xyz coordinates), and this viewpoint V is set. A screen S as a projection plane is virtually arranged between the object O and the object O. Normally, when a projection line LA is generated from each point of the object O composed of triangular polygons toward the viewpoint V, an object O ′ as a projection diagram is formed on the screen S as a collection of intersections with the projection line LA. Is done. In this way, the object O is perspectively projected on the screen S as the object O ′.

  Further, hidden surface removal refers to erasing a part of a surface that is hidden by a surface existing in front of an object and cannot be seen. In this embodiment, a method called “Z buffer method” is used. Used to remove hidden surfaces.

  The Z buffer method is a known method for performing hidden surface removal by comparing the distances in the depth (z-axis) direction between target objects for each pixel of the frame buffer 72 corresponding to the screen screen. In the Z buffer method, a Z buffer (not shown) that has the same resolution as the frame buffer 72 and stores a numerical value of the depth from the viewpoint (hereinafter referred to as “Z value”) for each pixel of the frame buffer 72. ) Is used. This Z buffer is provided in the VRAM 7.

  In this embodiment, the Z buffer method is adopted, but instead of this, a known “Z sort method” in which the frame buffer is overwritten in order from a distant object is used to hide the hidden surface. Erasing may be performed.

  In the object drawing process, the order of processing is determined for each of the plurality of objects, and the process is performed for each object according to the order of the processes. The order of this processing is arbitrarily determined in the Z buffer method.

  First, as a pre-process for drawing the first object, all the pixels in the frame buffer 72 are initialized by setting the values of all the pixels in the frame buffer 72 to a background color value, for example. Next, all the pixels in the Z buffer are initialized by setting the values of all the pixels in the Z buffer to the farthest (for example, infinite) value.

Next, perspective projection and scan conversion are performed on the object in the first order (hereinafter referred to as “object O ₁ ”). The scan conversion is a process for determining the pixels included in the polygon by acquiring the intersections between the sides of the polygons that make up the object and a predetermined scan line scanned on the screen. That is, the pixel on the scan line between the two intersections is the pixel inside the polygon.

Thereafter, a value of a distance (hereinafter referred to as a “Zo value”) of one pixel of the object O ₁ (polygon) with a virtual camera (not shown) installed at a predetermined position in the three-dimensional virtual space. ) Is calculated. Next, this Zo value is compared with the Z value of the pixel of the Z buffer corresponding to the pixel.

When this comparison result is Z> Zo, that is, when the distance for one pixel of the object O ₁ is closer to the camera than the current Z value of the Z buffer pixel, the Z value of the Z buffer pixel is set to the Z value. And the luminance value (hereinafter referred to as “luminance value K”) at the pixel of the object O ₁ is read from, for example, the VRAM 7 and stored in the frame buffer 72. In the setting of the luminance value K, work such as texture mapping is also performed at the same time.

  On the other hand, when the comparison result is Z <Zo, the Z value of the pixel in the Z buffer is left as it is, and the polygon is not drawn in that pixel. In the Z buffer method, the above-described processing is performed for all objects, and two-dimensional images for all objects are generated on the frame buffer 72.

  In this object drawing process, a non-moving object such as a background such as a mountain, sky, or building (hereinafter referred to as “static object”) is treated as one of the objects, and the rendering process is performed. In addition to a static object, an object such as a character that appears and moves in the game space (hereinafter referred to as a “dynamic object”) is also treated as one of the objects, and the rendering process is performed.

  Next, shading (shading) processing is performed, and the data after the shading processing is stored in the frame buffer 72. In the shading process, for example, a light map stored in advance in the VRAM 7 is used. Here, the light map is obtained by texturing luminance information (for example, luminance value) representing a static shadow drawn on the screen screen, which is obtained in advance by calculation. A light map is generated for each game stage in a game, for example. This light map has a unique coordinate system (hereinafter, these coordinates are referred to as “UV coordinates”), and the position where the luminance information is stored can be specified by the UV coordinates.

  In the shading process, the luminance information of the UV coordinates is acquired for the pixel to be processed with reference to the light map. The luminance value K ′ is calculated by multiplying or adding the acquired luminance information to the calculated luminance value K, thereby correcting the luminance value for each pixel. As a result, the portion that is exposed to light is drawn so as to be relatively bright, and the shaded portion is drawn to be relatively dark, so that a realistic screen image with a stereoscopic effect can be obtained.

  In addition, since the luminance information constituting the light map includes luminance information of a shadow (hereinafter referred to as “static shadow”) generated when a static object is irradiated with light, Static shadows are also drawn.

The RGB luminance value stored for each pixel in the frame buffer 72 is updated to the luminance value K ′ calculated by the shading process in the corresponding pixel. If the processing for all the pixels completion of object O, performs the same processing for the next object O _2, since all the objects for _{(O 1, O 2, ...} , O n, n is the number of objects) Similar processing is performed.

  The overlap process (S2) is a process of blending, that is, synthesizing overlap images, which are other images, so as to overlap the image (screen image) written in the frame buffer 72 in the object drawing process (S1).

  Examples of the overlap image include a shadow (hereinafter referred to as “dynamic shadow”) that is generated when a dynamic object is irradiated with light. The overlap processing related to the dynamic shadow composition processing will be described later. In addition, the overlap processing of the overlap image other than the dynamic shadow is omitted here because it is not directly related to the present embodiment.

  The effect addition process (S3) includes, for example, an effect process, a filter process, a screen process, and the like. The effect process is a process for writing particles (for example, particles such as blast and sparks) into the frame buffer 72. The filter process is a process for performing predetermined correction on the entire image data written in the frame buffer 72, for example, when expressing “moy”. By these processes, the image drawn on the screen image becomes more realistic, and the screen image can have a sense of reality. The screen process is a process of writing, in the frame buffer 72, a two-dimensional image that is displayed on the foremost side as viewed from the player, such as a gauge (eg, a physical strength gauge).

  Next, the overlap process (S2) will be described in detail. As shown in FIG. 2, the overlap process is configured by, for example, a cast process (S4) and a receive process (S5). The cast process and the receive process of the present embodiment are processes for synthesizing dynamic shadows to static objects, and other dynamic shadow synthesis processes (for example, self-drawing dynamic shadows on dynamic objects). Shadow processing) is executed as a separate process in the overlap process.

  In the cast process (S4), a shadow map necessary for drawing the dynamic shadow of the dynamic object is generated. In the receive process (S5), a process for determining whether or not to draw a dynamic shadow is performed for each pixel of the frame buffer 72, and the dynamic shadow is drawn on the screen image based on the determination result of the determination process. Done.

  Here, a general method using a “shadow map technique (a method for determining a pixel to be a shadow using a Z buffer method in a three-dimensional image space)”, which is a known technique for drawing a shadow on a screen image. How to draw shadows will be explained.

  First, a shadow map is used for the above-mentioned shadow map technique in general. Data is obtained by acquiring the distance from the light to the visible point for each pixel with the position of the light source (hereinafter referred to as “light”) as the viewpoint. It has become. Here, the visible point is a point that can be seen from the light side when the light is the viewpoint.

  In the generation of a shadow map, the distance from the light to the visible surface with the position of the light as the viewpoint using the Z buffer method, in other words, the distance from the light to the portion (for example, an object or the ground) where the light is applied Is acquired for each pixel as a Z value (hereinafter referred to as “depth value D2”). Note that when there are a plurality of lights, the shadow map is generated for each light.

  For example, as shown in FIG. 4, when the object O is arranged on the ground E, it is assumed that the object O is irradiated from the light L set in the three-dimensional virtual space. In such a case, in the pixel sma of the shadow map SM, the Oa point of the object O and the Ea point of the ground E exist in the irradiation direction, but the Oa point having the shortest distance from the light L is specified by the Z buffer method. The distance from the light L to the point Oa is stored as the depth value D2.

  Further, for example, considering the Eb point on the ground E shown in FIG. 4, the Eb point has the shortest distance from the light L in the irradiation direction of the pixel smb (the part where the light from the light L directly hits). . Therefore, the value of the distance from the light L to the point Eb is stored in the pixel smb as the depth value D2.

  In this way, each pixel of the shadow map SM stores the depth value D2 that is the distance to the portion where the light from the light L reaches, thereby generating the shadow map SM.

  Next, the determination of the presence or absence of a shadow in each pixel of the screen image when viewed from the camera viewpoint will be described. This determination is based on the distance (hereinafter referred to as “depth value D1”) of the object drawn on each pixel of the screen image and the depth value D2 stored in the corresponding shadow map SM. This is done by comparing. When the depth value D1 is larger than the depth value D2 (when it is farther than the distance that the light reaches from the light), it is determined that the pixel includes a shadow.

  For example, if attention is paid to the point Ea of the ground E drawn on one pixel of the screen S shown in FIG. 4, the distance (depth value D1) from the light L to the point Ea calculated by a predetermined calculation, and The distance (depth value D2) from the light L to the point Oa of the object O stored in the corresponding shadow map SM is compared. If the depth value D1 of the pixel in the frame buffer corresponding to the point Ea on the ground E is “30” and the depth value D2 corresponding to the pixel stored in the shadow map SM is “20”, the pixel Is identified as having a shadow.

  On the other hand, when the depth value D1 is smaller than or equal to the depth value D2, it is determined that the pixel does not include a shadow. Similarly, the presence or absence of a shadow is determined for all the pixels on the frame buffer, and drawing is performed for each pixel, whereby the screen image S in which the shadow is generated is drawn on the frame buffer.

  FIG. 5 is an image diagram of the screen image S shown in FIG. 4 stored in the frame buffer, and shows a state where no shadow of the object O is generated. FIG. 6 is a diagram showing a state when a shadow is generated for the screen image S shown in FIG.

  In the present embodiment, using the shadow map technique described above, a shadow map for drawing dynamic shadows is generated for each light in the cast process (S4), and a screen image of the dynamic shadow is received in the receive process (S5). Drawing to is done. Therefore, in the cast process (S4) of the present embodiment, the target for generating the shadow map is limited to only dynamic objects. For this reason, the depth value for an object such as a building to be drawn with “static shadow” is not stored in the shadow map. For example, information set for each object (for example, information set in advance using a flag or the like) is used for determining whether or not to generate a dynamic shadow. Further, when there is no dynamic object in the light irradiation direction of one pixel of the shadow map, the depth value D2 of the pixel is not updated. Since each pixel of the shadow map stores the farthest value from the light as an initial value, the initial value becomes the depth value D2 when updating is not performed. Note that the shadow map of this embodiment is stored in the VRAM 7.

  FIG. 7 is a flowchart showing the receive process (S5) shown in FIG. The receive process is a process in which the dynamic shadow of the dynamic object is blended (combined) with the screen image S drawn in the frame buffer 72.

  First, when there are a plurality of lights L, one light L is selected from the plurality of lights L (S11). Next, one pixel in the frame buffer 72 is selected (S12), and then drawing pixel processing is performed (S13). The drawing pixel processing determines whether or not to draw a dynamic shadow over a static object drawn in one pixel of the frame buffer 72, and when drawing a dynamic shadow, The luminance value and the mixing ratio α (0 ≦ α ≦ 1) are determined. The RGB luminance values and the mixing ratio α of the dynamic shadow are stored in a dynamic shadow buffer provided in the VRAM 7, for example. This drawing pixel process will be described later.

  Next, it is determined whether or not drawing pixel processing has been performed for all the pixels in the frame buffer 72 (S14). When the drawing pixel process has not been performed for all the pixels (S14: NO), the process returns to step S12.

  If drawing pixel processing has been performed for all pixels (S14: YES), it is determined whether drawing pixel processing for all pixels has been performed for all lights L (S15). When the drawing pixel processing of all the pixels is not performed for all the lights L (S15: NO), the process returns to step S11.

  When all of the lights L are subjected to the drawing pixel processing of all the pixels (S15: YES) and the dynamic shadow is drawn, the luminance value and the mixing rate α are read from the buffer provided in the VRAM 7 and the pixels of the frame buffer 72 are read. Processing for blending dynamic shadows every time, that is, drawing processing of dynamic shadows is performed (S16).

  Next, the drawing pixel process shown in step S13 of FIG. 7 will be described with reference to the flowchart shown in FIG. As described above, the drawing pixel processing determines whether or not to draw a dynamic shadow over a static object drawn in one pixel of the frame buffer 72, and when drawing a dynamic shadow, This is a process for setting the RGB luminance value and the mixing ratio α of the dynamic shadow.

  First, the depth value D1 of the object drawn in one pixel of the frame buffer 72 selected in step S12 of FIG. 7 is acquired by a predetermined calculation, and the depth value D2 of the dynamic shadow corresponding to this pixel is obtained. Read from the shadow map of the VRAM 7 (S21). For example, as shown in FIG. 9, when a dynamic shadow CS is generated in a character C as a dynamic object, attention is paid to a point f1 which is one pixel of the frame buffer 72, and a static object (this In this case, the depth value D1 of the ground) is acquired by a predetermined calculation. Here, as described above, the depth value D1 is a distance from the light L to the static object drawn on the pixel (point f1). Then, the depth value D2 of the dynamic object (character C) corresponding to the point f1 is read from the shadow map.

  When the depth value D1 is calculated by calculation in step S21 and the depth value D2 is read from the VRAM 7, it is determined whether or not to draw a dynamic shadow for the selected one pixel (S22). Specifically, whether or not to draw a dynamic shadow on the pixel is determined based on whether or not the depth value D1 of the pixel to be processed acquired in step S21 is larger than the depth value D2.

  When it is determined that the depth value D1 is equal to or less than the depth value D2 (S22: NO), it is determined that the dynamic shadow is not drawn for the selected one pixel. In this case, the RGB brightness values of the dynamic shadow are not set and the process ends. At this time, since the buffer for dynamic shadow is not updated, the initial value (for example, 0 value indicating a transparent color in the RGB value and 0 value in the α value) remains unchanged.

  On the other hand, if it is determined in step S22 that the depth value D1 is greater than the depth value D2 (S22: YES), it is determined that a dynamic shadow is to be rendered for the selected one pixel.

  When drawing a dynamic shadow for one selected pixel, whether or not a static shadow exists in the pixel based on the luminance data of the static shadow (whether or not a static shadow is drawn) ) Is determined. In this embodiment, it is determined whether or not a static shadow is drawn using the luminance data of the light map, but whether or not the static shadow is drawn on the pixel to be processed is described in the light map described above. Therefore, it is determined whether or not the static shadow is drawn by the following processing (steps S23 and S24).

  That is, in step S23, the dynamic shadow color of the dynamic shadow and the texture color of the static object on which the static shadow is drawn are acquired. Here, the dynamic shadow color refers to RGB luminance values set in advance for dynamic shadows (hereinafter referred to as “dynamic shadow color DS”). The dynamic shadow color DS is a basic luminance value (fixed value) of the dynamic shadow, and this value is always used when it does not overlap with the static shadow. The dynamic shadow color DS is stored in advance in the VRAM 7 or the like and is read out as necessary. Note that the dynamic shadow color DS of the present embodiment is a single fixed value. However, for example, a plurality of dynamic shadow colors DS may be used by switching for each game stage, and a single standard value is stored. The standard value may be increased or decreased for each game stage.

  The texture color refers to an RGB luminance value related to a static object drawn on one selected pixel (hereinafter referred to as “texture color SS”). The texture color SS is acquired from information reflecting the brightness information of the static shadow. In the present embodiment, the texture color SS is read and acquired from the light map used for the shading process described above, which also includes static shadow luminance information. Specifically, the luminance value at the UV coordinate position corresponding to the selected one pixel stored in the light map is read and used. For the texture color SS, the luminance value of the frame buffer 72 in which the static shadow is already drawn together with the static object may be used.

  Next, in step S24, it is determined whether or not the total value of the dynamic shadow color DS and the texture color SS is greater than a predetermined threshold value. In other words, it is determined whether or not the overlapping portion of the dynamic shadow color DS and the texture color SS is blacker than the predetermined color (whether it is dark). That is, as shown in FIG. 10, the dynamic shadow (see CS in FIG. 10) overlaps the static shadow (see BS in FIG. 10), and processing to make the dynamic shadow CS conform to the screen image should be performed. It is determined whether or not there is.

  When the total value of the dynamic shadow color DS and the texture color SS exceeds the threshold value, the texture color SS of the pixel to be processed includes the luminance value of the static shadow and stores a relatively large luminance value. It is assumed that it was done, and it is made to perform the process which adjusts dynamic shadow.

  More specifically, in step S24, the determination is made using a discriminant such as “DS × b + SS + A> threshold”. Here, “b” and “A” are correction values determined in advance according to the environment such as each scene (for example, stage) of the game drawn on the screen image and a predetermined place in the three-dimensional space. In particular, “b” is for adjusting the dynamic shadow color DS, and “A” is for adjusting the threshold value directly. Since “DS × b + SS + A” on the left side in the discriminant is a kind of evaluation function, the threshold value can be adjusted by changing the value of “b” and the value of “A” in the equation. This makes it possible to draw dynamic shadows according to the situation of each scene, such as when you want to draw dynamic shadows and static shadows in duplicate without completely adapting them to static shadows. Can draw.

  A discriminant such as “DS + SS> threshold” may be used in place of the discriminant “DS × b + SS + A> threshold”. Furthermore, a discriminant such as “SS> threshold” may be used. Further, in the process of step S24, in the determination of “DS × b + SS + A> threshold”, only the value of R of RGB may be used as the dynamic shadow color DS and the texture color SS, but not limited thereto, R, G, All values of B may be used in consideration, or only G or B may be used.

  When it is determined in step S24 that the total value of the dynamic shadow color DS and the texture color SS is larger than the threshold value (S24: YES), that is, the overlapping portion of the dynamic shadow color and the texture color is more than a predetermined color. If it is determined that the dynamic shadow is adjusted to be black, the difference value between the dynamic shadow color DS and the texture color SS is set as the RGB luminance value of the dynamic shadow (S25).

  Specifically, the value calculated by the evaluation function represented by the setting expression “DS × b−SS + A” is used as the RGB luminance value of the dynamic shadow. Also in this setting formula, by changing the values of “b” and “A” in the formula, the overlapping degree of the dynamic shadow and the static shadow can be finely adjusted according to the situation of each scene.

  For example, by changing the values of “b” and “A”, a dynamic shadow that overlaps a static shadow is rendered in a transparent color so that the player cannot recognize it, or is rendered as thin as the player can recognize. can do. In this embodiment, since the predetermined values are set to “b” and “A” according to the environment such as each scene of the game to be drawn on the screen image or a predetermined place in the three-dimensional space, the dynamic shadow And the static shadow can be expressed in a natural way.

  In the present embodiment, “b” and “A” in the setting formula used in step S25 are set to the same values as “b” and “A” in the discriminant used in step S24. However, for example, “a” different from “b” instead of “b”, and “B” different from “A” instead of “A” may be set.

  In place of the setting formula “DS × a−SS + A”, the setting formula “DS-SS” may be used as the luminance value of RGB of the dynamic shadow. Even in this case, if the dynamic shadow color DS and the static shadow color SS are equal, the difference value is “0”, and only the static shadow is drawn. The pixel area where the static shadow and the static shadow overlap does not become unnaturally dark. In addition, even if the dynamic shadow color DS and the texture color SS are different values, the luminance value of the pixel area where the dynamic shadow overlaps the static shadow and the luminance value of the pixel area where the dynamic shadow does not overlap are approximately equal. Therefore, only the overlapping pixel region is not drawn unnaturally.

  Thereafter, although not shown in FIG. 8, a filtering process for determining the mixing ratio α of the dynamic shadow is performed, and the RGB luminance value and the mixing ratio α of the dynamic shadow are obtained as a dynamic shadow buffer (VRAM 7). Stored in In the filtering process, the boundary portion of the dynamic shadow is smoothed so as not to be a so-called jaggy (for example, jagged edges). For example, known near-percentage filtering (PCF) is used. It is done. As a result, the boundary portion of the dynamic shadow can be expressed smoothly. The dynamic shadow buffer has the same configuration as the frame buffer 72. The luminance value and the mixing ratio α of the dynamic shadow are stored in the dynamic shadow buffer area corresponding to the selected pixel of the frame buffer 72.

  On the other hand, when it is determined in step S24 that the total value of the dynamic shadow color DS and the texture color SS is smaller than the threshold (S24: NO), that is, the overlapping portion of the dynamic shadow color DS and the texture color SS is If it is determined that the brightness is brighter than the predetermined color and the dynamic shadow is not familiar, the dynamic shadow color DS is set as the RGB luminance value of the dynamic shadow (S26). Then, after the above-described filtering process is performed to determine the mixing rate α, the dynamic shadow luminance value and the mixing rate α are stored in the dynamic shadow buffer (VRAM 7).

  In the present embodiment, the processing for making all the dynamic shadows drawn in the frame buffer 72 familiarize with the dynamic shadows shown in the drawing pixel processing in the flowchart of FIG. 8 is performed. For example, a camera (not shown) is used. For dynamic shadows having a relatively long distance (Z value) from the position to the dynamic shadows, the drawing may be performed without performing the above-described process. Dynamic shadows far from the camera position are relatively rarely displayed on the screen screen, so that the player does not feel particularly unnatural and can reduce the processing load of the game device. There are advantages such as.

  Specifically, a process of determining whether or not the distance (Z value) from the camera position of the object drawn on the pixel is greater than or equal to a predetermined value is added between step S22 and step S23 shown in FIG. If it is determined that the distance is greater than or equal to the predetermined value, the dynamic shadow color DS is set as the RGB luminance value of the dynamic shadow as it is. On the other hand, if the value is less than the predetermined value, the processes in steps S23 to S26 are executed.

  Of course, the scope of the present invention is not limited to the embodiment described above. For example, the content of the game described in the above embodiment can be applied to various games such as a battle game, an action game, or a role playing game. In addition, the game described in the present embodiment may be applied to an online game, where a player who participates in the online game competes with each other, or a team that forms a team with a plurality of players and competes with other teams. You may make it apply to.

It is a block block diagram which shows an example of the game device with which the game program which concerns on this invention is applied. It is the flowchart which showed the outline procedure of the rendering process. It is a conceptual diagram for demonstrating perspective projection. It is a conceptual diagram for demonstrating the production | generation of a shadow map. It is an example of the image figure of the screen image before an overlap process is performed. It is an example of the image figure of the screen image after an overlap process was performed. It is a flowchart which shows the receiving process shown in FIG. It is a flowchart which shows the shadow description process shown in FIG. It is a figure for demonstrating the case where the dynamic shadow is produced | generated with respect to a dynamic object. It is a figure which shows an example of the positional relationship of a static shadow and a dynamic shadow. It is a figure which shows an example of the positional relationship of the conventional building, a static object, and a dynamic object.

Explanation of symbols

1 game machine 2 CPU
3 drawing data generation processor 4 RAM
5 ROM
6 Drawing processor 7 VRAM
8 D / A converter 9 Audio processor 10 Amplifier 12 DVD-ROM drive 14 Monitor 15 Speaker 16 Operation controller 17 DVD-ROM
71 Texture buffer 72 Frame buffer B Building (Static object)
BS static shadow C character (dynamic object)
CS Dynamic Shadow E Ground L Light O Object SM Shadow Map S Screen Image V Viewpoint (Camera)

Claims (7)

Computer
A two-dimensional image in which one or more static objects that are fixedly arranged in a three-dimensional virtual space and one or more dynamic objects that are operatively arranged in the virtual space are projected from a predetermined viewpoint. Is a game program for functioning as a game device for creating and displaying on a display screen,
The computer,
Image creation means for creating the two-dimensional image on the frame buffer using the luminance data of the static object, the luminance data of the shadow, and the luminance data of the dynamic object for each pixel of the frame buffer;
Whether or not to draw a shadow of the dynamic object based on the positional relationship between a predetermined light source and the dynamic object for each pixel of the two-dimensional image on the frame buffer created by the image creation means First discriminating means for discriminating
Whether or not there is a shadow of the static object based on luminance data of the shadow of the static object in the pixel determined by the first determination means that the shadow of the dynamic object is drawn Second discriminating means for discriminating
Shadow data setting means for setting brightness data of the shadow of the dynamic object based on the determination result by the second determination means;
Based on the luminance data of the shadow of the dynamic object set by the shadow data setting means for the pixel to which the shadow of the dynamic object of the frame buffer is to be drawn, the shadow of the dynamic object is changed. A drawing means for drawing;
A game program characterized by functioning. The computer,
In the pixel determined that the shadow of the dynamic object is drawn by the first determining means, the luminance data of the shadow of the static object and the predetermined shadow of the dynamic object in the pixel are determined. Function as an adding means for adding brightness data of
The second determining means includes
In place of the luminance data of the shadow of the static object, it is determined whether or not there is a shadow of the static object based on a comparison result obtained by comparing the addition data obtained by the addition unit and a predetermined threshold value. The game program according to claim 1. The second determining means includes
If the addition data is greater than the predetermined threshold, determine that there is a shadow of the static object;
When the addition data is less than or equal to the predetermined threshold, it is determined that there is no shadow of the static object,
The shadow data setting means includes
When it is determined by the second determining means that the shadow of the static object exists, a subtraction value between the shadow luminance data of the static object and the shadow luminance data of the dynamic object is calculated as the dynamic value. If the second determination means determines that there is no shadow of the static object, the predetermined brightness data of the shadow of the dynamic object is set. The game program according to claim 2. The brightness data of the shadow of the static object is included in a light map stored in advance in the storage means,
The adding means includes
The brightness data corresponding to the pixel determined to be the shadow of the dynamic object drawn by the first determination unit is used as the brightness data of the static object shadow by reading from the light map. Item 4. A game program according to Item 2 or 3. The adding means includes
The game program according to any one of claims 2 to 5, further comprising correction value giving means for giving correction values to the shadow luminance data of the static object and the shadow luminance data of the dynamic object.   A computer-readable recording medium on which the game program according to any one of claims 1 to 5 is recorded.   A computer that executes the game program according to claim 1.

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