JP4827250B2 - Program, information storage medium, and image generation system - Google Patents

Description

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

  In recent years, an image generation system that generates an object such as a character placed and set in a virtual three-dimensional space (hereinafter referred to as an “object space”) as a predetermined image based on a virtual camera (a given viewpoint) is practical. It has become.

  Such an image generation system has come to be used in various systems as being able to experience virtual reality. In particular, in a game system, it is important for improving entertainment and entertainment. Is being viewed.

  Conventionally, in such an image generation system, in order to express a sense of perspective in an image seen from a virtual camera, there is a method of performing depth cueing processing that combines a distant color with an object color according to the distance from the virtual camera. Are known.

In particular, recently, a parameter for linear interpolation between the object color and the target color set as the distant view color is prepared, and according to the distance from the viewpoint in the virtual camera using such a parameter. Representative methods for synthesizing colors are known.
Japanese Patent No. 3656062

  However, in the image generation system as described above, the composition ratio of the object color and the composition ratio of the distant view color have an interpolation relationship, so that the scene in the object space is expressed in detail. There are many cases where this is not possible.

  The present invention has been made in view of the above circumstances, and its object is to provide a program and an information storage capable of expressing a wider variety of situations and generating a realistic image by simple processing. To provide a medium and an image generation system.

  (1) The present invention is an image generation system for generating an image visible from a virtual camera, and sets an object space setting unit for setting an object in an object space, and a position and an orientation of the virtual camera in the object space A virtual camera control unit, and when rendering the image of the object viewed from the virtual camera, the object color and a given depth cueing color are associated with the depth value of the object relative to the virtual camera. A depth cueing processing unit that performs a depth cueing process to be combined, and the depth cueing processing unit sets a first parameter having an attenuation characteristic with respect to the depth value as a color composition ratio of the object And a second parameter having an increasing characteristic with respect to the depth value. The set as depth cueing color synthesis rate, based on the first parameter and the second parameter relates to an image generation system for synthesizing the color of the object and the depth cueing color. The present invention also relates to a program that causes a computer to function as each of the above-described units and a computer-readable information storage medium that stores such a program.

  According to the present invention, when performing the depth cueing process, the composition ratio of the object color is set by the first parameter, and the composition ratio of the depth cueing color is determined by the second parameter different from the first parameter. Set. Therefore, according to the present invention, poor visibility and the color of the atmosphere and ambient light can be expressed in detail by separately adjusting the object color and the depth cueing color. As a result, according to the present invention, various situations such as clear scenes of air, weather on cloudy days, and time zones such as morning to evening / night are more freely and more detailed than conventional methods. Can be expressed.

  (2) In the image generation system, the program, and the information storage medium of the present invention, the depth cueing processing unit includes a first start depth value at which the first parameter starts attenuation according to the depth value, and Based on the first end depth value at which the first parameter ends attenuation according to the depth value, the first parameter is set according to the depth value of the object, and the second parameter is Based on the second start depth value that starts increasing according to the depth value and the second end depth value where the second parameter ends increasing according to the depth value, the depth value of the object is calculated. A corresponding second parameter may be set.

  In this way, the characteristic change of each parameter with respect to the depth value can be individually adjusted based on the start depth value and the end depth value. For this reason, for example, various situations can be made by making the first start depth value and the second start depth value different from each other, or making the first end depth value and the second end depth value different from each other. Can be expressed. That is, according to this aspect, even when the depth (corresponding to the depth value) with respect to the virtual camera is the same, it is possible to realize a case where the composition ratio of the object color and the composition ratio of the depth cueing color are different. This situation can be expressed more freely and in detail.

  Further, in this aspect, the first parameter is set by making the first start depth value and the second start depth value the same, and by making the first end depth value and the second end depth value the same. And the second parameter can be interpolated, so that not only special depth cueing expression but also conventional depth cueing expression is possible, which is highly convenient.

  (3) Further, in the image generation system, the program, and the information storage medium of the present invention, the depth cueing processing unit includes a color that is added as a distant view to a celestial sphere object centered on the virtual camera in the object space. The color assigned to the intersection between the viewing direction of the virtual camera and the celestial sphere object may be set as the depth cueing color.

  In this way, since the color attached to the celestial sphere object is used as a distant view, the diffuse reflection of sunlight such as fog, gas, or dusk is accurately expressed compared to the case where the depth cueing color is determined in advance. can do. That is, according to this aspect, it is possible to dynamically reflect changes in the atmospheric state and the color of ambient light in the depth cueing color.

  (4) In the image generation system, the program, and the information storage medium according to the present invention, the depth cueing processing unit may detect an angular difference between the line-of-sight direction of the virtual camera and the direction of a given light source set in the object space. The depth cueing color may be set by multiplying the color of the light source by a parameter that changes according to the above.

  In this way, a change in the color of light incident in the line-of-sight direction can be expressed according to the angle difference between the light source direction and the line-of-sight direction, so that various situations can be expressed more accurately.

  (5) In the image generation system, the program, and the information storage medium of the present invention, the depth cueing processing unit is a color that is paired with the color of the given light source set in the object space and the color of the light source. The depth cueing color is set by interpolation based on a parameter that changes in accordance with an angle difference between the viewing direction of the virtual camera and the direction of a given light source set in the object space. May be.

  In this way, the direction in which the color that is paired with the light source direction can be set, for example, as a direction that is 180 degrees opposite to the light source with respect to the virtual camera. In the case where the sky color is not constant (a situation in which the sunset is dark in the east sky even in the case of sunset in the west sky), an appropriate depth cueing color can be set according to the viewing direction.

  (6) In the image generation system, program, and information storage medium of the present invention, the first parameter is a first start depth value at which attenuation starts according to the depth value, and the first parameter is the depth value. A first ending depth value ending attenuation according to the second parameter, a second starting depth value at which the second parameter starts increasing according to the depth value, and the second parameter according to the depth value. At least one of the second ending depth values ending the increase is the weather set for the object space, the time to travel in the object space, the position of the virtual camera in the object space, and the object space You may make it change based on at least any one of direction of the virtual camera.

  In this way, it is possible to accurately represent the difference in situation due to changes in the weather and time of the object space or the position and orientation of the virtual camera.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. In addition, all the configurations described in the present embodiment are not necessarily essential configuration requirements of the present invention.

1. Configuration First, the configuration of an image generation system (game system) in the present embodiment will be described with reference to FIG. FIG. 1 is an example of a functional block diagram of an image generation system in the present embodiment. Note that the image generation system of this embodiment may have a configuration in which some of the components (each unit) in FIG. 1 are omitted.

  The operation unit 160 is for a player to input operation data, and the function can be realized by a lever, a button, a steering, a microphone, a touch panel display, a housing, or the like.

  The storage unit 170 serves as a work area for the processing unit 100, the communication unit 196, and the like, and its function can be realized by a RAM, a VRAM, or the like. The storage unit 170 of the present embodiment defines a main storage unit 171 that is a work area of the processing unit 100, a drawing buffer 172 that stores color information (image information) of pixels constituting the image, and objects. Object data storage unit 173 storing vertex data (object data, model data), texture storage unit 174 storing various textures mapped to the object, Z value (depth value) used for hidden surface removal processing, etc. Z buffer 176 in which is stored). Note that some of these may be omitted.

  The information storage medium 180 (computer-readable medium) stores programs, data, and the like, and functions as an optical disk (CD, DVD), magneto-optical disk (MO), magnetic disk, hard disk, and magnetic tape. Alternatively, it can be realized by a memory (ROM).

  The information storage medium 180 stores a program (data) for the processing unit 100 to perform various processes of the present embodiment. That is, the information recording medium 180 stores a program for causing a computer to function as each unit of the present embodiment (a program for causing a computer to execute processing of each unit).

  The display unit 190 outputs an image generated according to the present embodiment, and its function can be realized by a CRT, LCD, touch panel display, HMD (head mounted display), or the like.

  The sound output unit 192 outputs the sound generated by the present embodiment, and its function can be realized by a speaker, headphones, or the like.

  The portable information storage device 194 stores player personal data, game save data, and the like. Examples of the portable information storage device 194 include a memory card and a portable game device.

  The communication unit 196 performs various controls for communicating with the outside (for example, a host device or other image generation system), and functions thereof are hardware such as various processors or communication ASICs, It can be realized by a program.

  Note that a program (data) for causing a computer to function as each unit of the present embodiment is distributed from the information storage medium of the host device (server) to the information storage medium 180 (storage unit 170) via the network and communication unit 196. May be. Use of the information storage medium of such a host device (server) can also be included in the scope of the present invention.

  The processing unit 100 (processor) performs processing such as game processing, image generation processing, or sound generation processing based on operation data and programs from the operation unit 160. Here, the game process includes a process for starting a game when a game start condition is satisfied, a process for advancing the game, a process for placing an object such as a character or a map, a process for displaying an object, and a game result calculation. Or a process for ending the game when a game end condition is satisfied. The processing unit 100 performs various processes using the main storage unit 171 in the storage unit 170 as a work area. The functions of the processing unit 100 can be realized by hardware such as various processors (CPU, DSP, etc.), ASIC (gate array, etc.), and programs.

  In particular, the processing unit 100 of the present embodiment includes an object space setting unit 110 that sets various objects in the object space, a movement / motion processing unit 112 that performs movement / motion calculation of a moving object in the object space, and a virtual camera. A virtual camera control unit 114 that controls the image, an image generation unit 120 that generates an image viewed from the virtual camera, and a sound generation unit 130 that generates sound. Note that some of these may be omitted.

  The object space setting unit 110 includes various objects (polygons, free-form surfaces or subdivision surfaces) representing display objects such as character objects, cars, tanks, buildings, trees, pillars, walls, maps (terrain), and virtual spheres (celestial spheres). The object is configured to place and set in the object space.

  That is, the object space setting unit 110 determines the position and rotation angle (synonymous with orientation and direction) of the object (model object) in the world coordinate system, and the rotation angle (X, Y, Z) is determined at that position (X, Y, Z). , Rotation angle around Y, Z axis).

  In particular, in the present embodiment, the object data storage unit 173 defines moving object (car, character, etc.), fixed object (building, etc.), background object (map, terrain, virtual sphere (celestial sphere), etc.). Object data to be stored is stored. Specifically, the object data storage unit 173 stores object data that defines an object by the vertex position coordinates set in an arbitrary local coordinate system. In the object data, texture coordinates, color (vertex color), normal vector (normal data), α value, and the like may be associated with the vertex position coordinates. Then, the object space setting unit 110 performs a process of setting an object in the object space based on the object data stored in the object data storage unit 173.

  The movement / motion processing unit 112 performs a movement / motion calculation (movement / motion simulation) of a moving object (such as a tool used by a character in addition to a car or an airplane). That is, the movement / motion processing unit 112 is based on the operation data input by the player through the operation unit 160, the set parameters and attributes, the program (movement / motion algorithm), various data (motion data), and the like. A process for moving the object in the object space or controlling the motion (motion, animation) of the moving object is performed.

  Specifically, the movement / motion processing unit 112 according to the present embodiment stores object movement information (position, rotation angle, speed, or acceleration) and movement information (position or rotation angle of each part object) for one frame. A simulation process is sequentially obtained every (for example, 1/60 seconds).

  Here, the frame is a unit of time for performing object movement / motion processing (simulation processing) and image generation processing. In this embodiment, the frame rate may be fixed every frame or may be variable according to the processing load.

  The virtual camera control unit 114 performs a virtual camera (viewpoint) control process for generating an image viewed from a given (arbitrary) viewpoint in the object space. Specifically, a process for controlling the position (X, Y, Z) or the rotation angle (rotation angle about the X, Y, Z axes) of the virtual camera (process for controlling the viewpoint position and the line-of-sight direction) is performed.

  For example, when shooting an object (eg, character, ball, car) from behind using a virtual camera, the virtual camera position or rotation angle (virtual camera position) is set so that the virtual camera follows changes in the position or rotation of the object. Control). In this case, the virtual camera can be controlled based on information such as the position, rotation angle, or speed of the object obtained by the movement / motion processing unit 112. Alternatively, the virtual camera may be controlled to rotate at a predetermined rotation angle or to move along a predetermined movement path. In this case, the virtual camera is controlled based on the virtual camera data for specifying the position (movement path) or rotation angle of the virtual camera. When there are a plurality of virtual cameras (viewpoints), the above control process is performed for each virtual camera.

  The image generation unit 120 performs drawing processing based on the results of various processes (game processing) performed by the processing unit 100, thereby generating an image and outputting the image to the display unit 190. When generating a so-called three-dimensional game image, first, object data (model data) including vertex data (vertex position coordinates, texture coordinates, color data, normal vector, α value, etc.) of each vertex of the object (model) ) Is input, and vertex processing is performed based on the vertex data included in the input object data. When performing the vertex processing, vertex generation processing (tessellation, curved surface division, polygon division) for re-dividing the polygon may be performed as necessary. In vertex processing, geometry processing such as vertex movement processing, coordinate transformation (world coordinate transformation, camera coordinate transformation), clipping processing, perspective transformation, or light source processing is performed, and an object is configured based on the processing result. Change (update, adjust) the vertex data given for the vertex group. Then, rasterization (scan conversion) is performed based on the vertex data after the vertex processing, and the surface of the polygon (primitive) is associated with the pixel. Subsequent to rasterization, pixel processing (fragment processing) for drawing pixels constituting an image (fragments constituting a display screen) is performed. In pixel processing, various processes such as texture reading (texture mapping), color data setting / changing, translucent composition, anti-aliasing, etc. are performed to determine the final drawing color of the pixels that make up the image, and perspective transformation is performed. The drawing color of the object is output (drawn) to the drawing buffer 172 (buffer that can store image information in units of pixels; VRAM, rendering target). That is, in pixel processing, per-pixel processing for setting or changing image information (color, normal, luminance, α value, etc.) in units of pixels is performed. Thereby, an image that can be seen from the virtual camera (given viewpoint) set in the object space is generated. Note that when there are a plurality of virtual cameras (viewpoints), an image can be generated so that an image seen from each virtual camera can be displayed as a divided image on one screen.

  It should be noted that the vertex processing and pixel processing performed by the image generation unit 120 are performed by hardware that enables a polygon (primitive) drawing process to be programmed by a shader program written in a shading language, so-called programmable shaders (vertex shaders and pixel shaders). It may be realized. Programmable shaders can be programmed with vertex-level processing and pixel-level processing, so that the degree of freedom of rendering processing is high, and the expressive power can be greatly improved compared to fixed rendering processing by hardware. .

  The image generation unit 120 performs geometry processing, texture mapping, hidden surface removal processing, α blending, and the like when drawing an object.

  In the geometry processing, processing such as coordinate conversion, clipping processing, perspective projection conversion, or light source calculation is performed on the object. The object data (positional coordinates of object vertices, texture coordinates, color data (luminance data), normal vector, α value, etc.) after geometry processing (after perspective projection conversion) is stored in the main storage unit 171. The

  Texture mapping is a process for mapping a texture (texel value) stored in the texture storage unit 174 of the storage unit 170 to an object. Specifically, the texture (surface properties such as color (RGB) and α value) is read from the texture storage unit 174 of the storage unit 170 using the texture coordinates set (given) to the vertex of the object. Then, a texture that is a two-dimensional image is mapped to an object. In this case, processing for associating pixels with texels, bilinear interpolation or the like is performed as texel interpolation. In particular, in this embodiment, a distant view texture (background texture) for showing a distant view (background) in the object space is read from the texture storage unit 174 of the storage unit 170, and set so that the virtual camera is set at the center. The distant view texture read out is mapped onto the virtual sphere object (celestial sphere object).

  In the present embodiment, the color distribution (texel pattern) of the distant view texture mapped to the virtual sphere object can be dynamically changed. In this case, a distant view texture having a different color distribution (pixel pattern) may be dynamically generated, or a plurality of distant view textures having different color distributions are prepared in advance, and the distant view texture to be used is dynamically switched. You may do it.

  As the hidden surface removal processing, hidden surface removal processing can be performed by a Z buffer method (depth comparison method, Z test) using a Z buffer (depth buffer) in which a Z value of a drawing pixel is stored. That is, when drawing pixels corresponding to the primitive of the object are drawn, the Z value stored in the Z buffer is referred to. Then, the Z value of the referenced Z buffer is compared with the Z value at the drawing pixel of the primitive, and the Z value at the drawing pixel is a Z value (for example, a small Z value) on the near side when viewed from the virtual camera. In some cases, the drawing process of the drawing pixel is performed and the Z value of the Z buffer is updated to a new Z value.

  α blending (α synthesis) is a translucent synthesis process (usually α blending, addition α blending, subtraction α blending, or the like) based on an α value (A value). For example, in normal α blending, a process for obtaining a color obtained by combining two colors by performing linear interpolation with the α value as the strength of synthesis is performed.

  The α value is information that can be stored in association with each pixel (texel, dot), and is, for example, plus alpha information other than color information indicating the luminance of each RGB color component. The α value can be used as mask information, translucency (equivalent to transparency and opacity), bump information, and the like.

  In this embodiment, the image generation unit 120 includes a depth cueing processing unit 122.

  The depth cueing processing unit 122 uses the depth value indicating the distance between the virtual camera and the object to be rendered (the distance between the virtual camera and the vertex in the viewpoint coordinate system) to determine the color of the object to be rendered (hereinafter, (Also referred to as “object color”) and depth cueing processing for combining the depth cueing color.

  Specifically, the depth cueing processing unit 122 attenuates the color composition ratio of the object in accordance with the depth value (an example of a first parameter: hereinafter referred to as “object color parameter”), and far. Depth cueing based on a parameter (an example of a second parameter: hereinafter referred to as “depth cueing color parameter”) that increases the composition ratio of the depth cueing color set as a scenery or the like according to the depth value. Process.

  Then, the depth cueing processing unit 122 multiplies the luminance value of the color components (R, G, B) constituting the color of the object by the object color parameter, and also sets the color components ( R, G, B) luminance values are multiplied by depth cueing color parameters, and each multiplication result is added to obtain the drawing pixel color for the object after depth cueing processing. The luminance values of the color components (R, G, B) constituting the color of the drawing pixel are output to the drawing buffer 172.

  In addition, the depth cueing processing unit 122 performs time (time zone) of the object space such as morning, noon, evening, or night, the weather set in the object space such as rain, fog, and the amount thereof, and the highland or mountainous area. The object color parameter and the depth cueing color parameter used for the above calculation are set based on the position in the object space where the virtual camera is set or its direction.

  For example, the depth cueing processing unit 122 starts the start point (an example of the first start depth value) and the end point (an example of the first end depth value) at which the object color parameter starts attenuation according to the depth value. Is set based on the situation when generating an image visible from the virtual camera, such as the weather and time (time zone) of the object space or the position and orientation of the virtual camera. In addition, for example, the depth cueing processing unit 122 starts the increase of the depth cueing color parameter according to the depth value (an example of the second start depth value) and the end point (second end depth value). Is set based on the situation when generating an image that is visible from the virtual camera, such as the weather and time (time zone) of the object space or the position and orientation of the virtual camera. That is, in the present embodiment, the object color parameter and the depth cueing parameter corresponding to the distance relationship between the virtual camera and the drawing target object are obtained based on the change characteristics determined by the start point and the end point. In this embodiment, since the start point and end point for the object color parameter and the start point and end point for the depth cueing color parameter are set individually, each parameter is obtained independently. Can be done.

  The sound generation unit 130 performs sound processing based on the results of various processes performed by the processing unit 100, generates game sounds such as BGM, sound effects, and sounds, and outputs them to the sound output unit 192.

  Note that the image generation system of the present embodiment may be a system dedicated to the single player mode in which only one player can play, or may be a system having a multiplayer mode in which a plurality of players can play.

  In addition, when a plurality of players play, game images and game sounds provided to the plurality of players may be generated using one terminal, or connected via a network (transmission line, communication line), etc. It may be generated by distributed processing using a plurality of terminals (game machine, mobile phone).

2. 2. Method according to this embodiment 2.1 Outline of Depth Cueing Process According to this Embodiment Next, an outline of the depth cueing process according to this embodiment will be described with reference to FIGS. 2 and 3.

  2 is a diagram for explaining the conventional depth cueing processing, and FIG. 3 is a diagram for explaining the depth cueing processing of the present embodiment.

  Usually, in the real world, the scenery becomes dazzling as you move farther from the viewpoint, and even in a virtual reality world such as a game, the object in the far view has a clear outline If so, it gives an unnatural impression to the player.

  For this reason, recently, a technique called depth cueing processing is known as one technique for expressing an image of an object in a distant view (background) more naturally and realistically.

  This depth cueing process is a process executed when the hidden surface removal process is executed and the drawing color of each drawing pixel, that is, the luminance value of the color component of each drawing pixel is specified, and is the distance from the viewpoint. Accordingly, the color of the object is brought close to a target color called a depth cueing color (for example, a color set as a background color), and is executed as image processing for blurring an object in a distant view (background). The depth cueing process is also used for an effect process (so-called fog process) that simulates the appearance of fog in the object space.

  Conventionally, in this depth cueing process, as shown in FIG. 2, a parameter (for example, α value) for linearly interpolating between the color of an object and a target color (depth cueing color) set as a distant view. Is used to reflect the depth cueing effect corresponding to the distance (depth value L) from the virtual camera to the color of the drawing pixel constituting the object to be drawn.

That is, in the conventional depth cueing process, as shown in (Equation 1), the luminance values (R _OB , G _OB , B _OB ) constituting the object color and the luminance values (R _D ) constituting the depth cueing color are shown. , G _D , B _D ) are linearly interpolated by a composition ratio r, which is a single parameter set according to the Z value, to obtain the luminance value (R, G, B) of the color of the drawing pixel. It was.

    In (Expression 1), conventional (R, G, B) indicates the luminance value of each color component constituting the color of the drawing pixel that has been subjected to depth cueing processing by a conventional method.

  In FIG. 2, L1 indicates a depth value L at which the effect of the depth cueing process starts to be reflected on the drawing pixel, and L2 indicates a depth value L at which the effect of the depth cueing process reflected on the drawing pixel becomes constant. Indicates. That is, as shown in FIG. 2, in the range where the depth value L is 0 to L1, the color of the object is the color of the drawing pixel, and in the range where the depth value L is L2 or later, the depth cueing color is the color of the drawing pixel. Become.

  However, in such a conventional depth cueing process, the substantial composition ratio “1-r” of the object color (object color) and the substantial composition ratio “r” of the depth cueing color are interpolated. (In the section of L1 to L2 in FIG. 2, the object color decreases at a constant rate and the depth cueing color increases at a constant rate), the scene in the object space in detail There were many cases where it was not possible to express.

  Therefore, in this embodiment, as shown in FIG. 3, the object color parameter PO and the depth cueing color parameter PD are individually set, and the object color is attenuated according to the distance from the viewpoint (depth value L). And the degree by which the depth cueing color is added and synthesized in accordance with the distance from the viewpoint (depth value L) is obtained separately and independently.

  Specifically, (1) processing for setting object color parameters and depth cueing color parameters (hereinafter referred to as “parameter setting processing”), and (2) processing for setting depth cueing colors (hereinafter referred to as “parameter setting processing”). , “Dep squeezing color setting processing”) and (3) processing for synthesizing the object color and the depth queuing color (hereinafter referred to as “compositing processing”) are referred to as depth queuing processing. To do.

  As described above, according to the method of the present embodiment, by adjusting the color of the object and the depth cueing color individually, the poor visibility and the color of the atmosphere or ambient light can be accurately matched to the color of the drawing pixel. Since it can be reflected, for example, it is possible to express various situations more freely and accurately, such as expressions based on time zones such as clear scenery of the air, weather on cloudy days, morning to evening / night etc. become able to.

2.2 Parameter Setting Processing Next, parameter setting processing according to the present embodiment will be described using FIG. 3 in the same manner as described above.

  In this embodiment, when calculating the color of each drawing pixel constituting the display image, in the object space, such as the virtual time, weather, or the position and orientation of the virtual camera (viewpoint) that are proceeding in the object space Based on the set virtual situation, the object color parameter and the depth cueing color parameter can be set.

  Specifically, the point at which the composition rate of the object color starts to attenuate according to the depth value L (first start depth value: hereinafter referred to as “attenuation start point”) Sr and the composition rate of the object color is the depth. A point (first end depth value: hereinafter referred to as “attenuation end point”) Gr corresponding to the value L is set for each situation, and an attenuation start point Sr and an attenuation end point Gr for each situation are set. As shown in FIG. 3A, an object color parameter PO having attenuation characteristics is set between the attenuation start point Sr and the attenuation end point Gr.

  For example, in the present embodiment, the object color parameter PO, which is the composition ratio of the object colors, is normalized to a range of 0 to 1.0, and as shown in (Expression 2), the attenuation start point Sr and the attenuation end point An object color parameter (combination rate) PO is set based on Gr.

  Here, “L” in (Expression 2) indicates a depth value L that is the distance from the virtual camera of the object to be rendered. Further, in this embodiment, depth cueing processing in which the object color is attenuated is performed when L> Sr, and the object color parameter PO is clamped to “0” when L> Gr. . If L <Sr, the object color parameter PO may be clamped to “1.0”.

  Further, in the present embodiment, with respect to the depth cueing color parameter, a point at which the composition ratio of the depth cueing color starts to increase according to the depth value L (second start depth value: hereinafter referred to as “increase start point”). Si and the point at which the composition ratio of the depth cueing color finishes increasing according to the depth value L (second end depth value: hereinafter referred to as “increase end point”) Gi is set for each situation. Based on the increase start point Si and the increase end point Gi, as shown in FIG. 3B, the depth cueing color parameter PD having an increase characteristic between the increase start point Si and the increase end point Gi. Is set.

  For example, in this embodiment, similarly to the object color parameter, the depth cueing color parameter, which is the composition ratio of the depth cueing color, is normalized to a range of 0 to 1.0, as shown in (Expression 3). As described above, the depth cueing color parameter (combination rate) PD is set based on the increase start point Si and the increase end point Gi.

  Here, “L” in (Expression 3) indicates a depth value L that is the distance from the virtual camera of the object to be rendered. In this embodiment, depth cueing processing is performed in which depth cueing colors are added and combined when L> Si, and the depth cueing color parameter PD is “ Clamped to 1.0 ". When L <Si, the depth cueing color parameter PD may be clamped to “0”.

  In this embodiment, since the attenuation start point, increase start point, attenuation end point, and increase end point can be set for each situation, the attenuation start point and the increase start point can be made different for each situation, or the attenuation end point can be set. The point and the increase end point can be made different. However, in an arbitrary situation, the attenuation start point and the increase start point can be made the same, or the attenuation end point and the increase end point can be made the same.

  Incidentally, in the example shown in FIGS. 3A and 3B, the object color parameter and the depth cueing color parameter are set as parameters that change linearly with respect to the depth value L. However, the parameters may be changed in a quadratic function manner or an exponential manner according to the situation.

  For example, as shown in (Equation 4) and (Equation 5), the PO obtained in (Equation 2) and the PD obtained in (Equation 3) are respectively normalized to 0 to 1.0 by squaring. It is also possible to set an object color parameter PO ′ and a depth cueing color parameter PD ′ that change in a quadratic function within a range.

2.3 Depth Cueing Color Setting Processing Next, depth cueing color setting processing according to the present embodiment will be described with reference to FIGS. 4 to 6.

  First, in this embodiment, a method of setting a depth cueing color according to the direction of the virtual camera (so-called line-of-sight direction) is adopted.

  For example, as shown in FIG. 4, a texture (distant view texture, background texture) for setting a distant view BG is mapped to a virtual sphere object SB (celestial sphere object) set around the position V of the virtual camera in the object space. The color BG attached to the intersection of the viewing direction A of the virtual camera VC and the virtual sphere object SB can be set as the depth cueing color DC.

  According to the method of the present embodiment, the depth cueing color DC can be acquired from the distant view BG attached to the virtual sphere object SB. Therefore, the depth cueing color DC that accurately reflects the sky pattern reflected in the viewing direction is set. be able to.

  In the example shown in FIG. 4, the distant view BG attached to the intersection between the visual line direction A of the virtual camera VC and the virtual sphere object SB is set by applying the example shown in FIG. The depth cueing color DC may be set by interpolating the light source color LC based on the angle difference θ between the visual line direction A and the light source direction L of the virtual camera VC.

  As another example of the method of the present embodiment, as shown in FIG. 5, the color LC of the light source for setting the ambient light and the color (environment set in the direction M 180 degrees different from the direction in which the light source is set). Depth cueing by interpolating a color paired with the color of the light source (for example, black) MC based on an interpolation parameter that changes in accordance with the angle difference θ between the line-of-sight direction A of the virtual camera VC and the direction L of the light source A color DC may be set.

  That is, in the example shown in FIG. 5, the inner product value “cos θ” that changes in accordance with the angle difference θ between the visual line direction A of the virtual camera VC and the light source direction L (corresponding to the inner product of the visual line direction A and the light source direction L). As the interpolation parameter, as shown in (Equation 6), the depth cueing color DC is obtained by linearly interpolating the light source color LC and the color MC paired with the light source color LC by “cos θ”. Is set. In (Expression 6), when cos θ is negative (cos θ <0), cos θ is clamped to 0.

  According to the example shown in FIG. 5, the depth cueing is performed so as to follow the change in the line-of-sight direction A of the virtual camera VC in a situation where the sunset is dim in the east sky even in the west sky. Since the color DC can be changed, various situations can be expressed more accurately.

  In the example shown in FIG. 5, the color MC that is paired with the light source color LC is set in a direction M that is 180 degrees different from the light source direction L, but other than 180 degrees, for example, 150 degrees or 120 degrees. A color MC that is paired with the color LC of the light source may be set in an arbitrary angle direction.

In the example shown in FIG. 5, “cos θ” is used as an interpolation parameter that changes according to the angle difference θ, but “cos ² θ” may be used as an interpolation parameter depending on the situation of the object space.

  As another example of the method of the present embodiment, as shown in FIG. 6, the depth cueing is performed by adjusting the color LC of the light source that sets the ambient light based on the line-of-sight direction A and the direction L of the light source. The color DC may be set.

  That is, in the example shown in FIG. 6, the cosine “cos θ” that changes in accordance with the angle difference θ between the viewing direction A of the virtual camera VC and the direction L of the light source that sets the ambient light is used as an adjustment parameter. As shown in Expression 7), the depth cueing color DC is set by multiplying the color LC of the light source by the adjustment parameter. In (Expression 7), when cos θ is negative (cos θ <0), cos θ is clamped to 0.

According to the example illustrated in FIG. 6, for example, when the line-of-sight direction A changes with respect to the light source direction L, it is possible to express a change in color according to the angle difference θ. However, as described above, instead of using “cos θ” as the adjustment parameter, “cos ² θ” may be multiplied by the color LC of the light source by the situation of the object space.

  In the above description, the case where there is one type of light source has been described as an example. However, even if a plurality of two or more types of light sources such as the sun, the moon, and the outside light are set in the object space, the above-described concept To set the depth cueing color DC.

  In addition, as a modification of the method of the present embodiment, the depth cueing color DC is set according to various situations such as the virtual time in the object space, the weather in the object space, or the position / orientation of the virtual camera. can do.

  For example, the time zone in the object space is determined based on the virtual time progressing in the object space, “white” in the “morning” time zone, “blue”, “evening” in the “daytime” time zone. In the time unit “”, “black” may be set as the depth cueing color DC in the time zone of “red” and “night”. Even in the “morning” time zone, when it is close to “noon”, a bluish “white” or the like may be set as the depth cueing color DC.

  As for the weather in the object space, the depth cueing color DC is “blue” when “sunny”, “white” when “cloudy” occurs, or “white” when “mist” occurs. You may make it set as. In this case, the depth cueing color DC may be set by combining the color set according to the time zone and the color set according to the weather.

  Furthermore, regarding the position or orientation of the virtual camera, “white” is set as the depth cueing color DC when the virtual camera is at the top of the mountain, and “gray” is set as the depth cueing when the virtual camera is at the top of the mountain. You may make it set as ing color DC. Also, depending on the direction to the light source that sets the ambient light set in the object space such as the sun, the color set by adding “white” or “black” to the color set in the time zone or weather is depth. You may make it set as cueing color DC.

2.4 Composition Processing In this embodiment, the object color OC and the depth cueing color DC are based on the object color parameter PO, the depth cueing color parameter PD, and the depth cueing color DC set as described above. Are combined by performing the calculation shown in (Equation 8) to calculate the color C of the drawing pixel.

Specifically, the object color OC (R _OC , G _OC , B _OC ) is multiplied by the object color parameter PO shown in (Equation 2) and attenuated according to the depth value L (Ro, Go). , Bo), and the depth cueing color DC (R _DC , G _DC , B _DC ) is multiplied by the depth cueing color parameter PD shown in (Equation 3) and added according to the depth value L. that depth cueing color is calculated _{(R D, G D, B} D) a.

Then, the object color (Ro, Go, Bo) and the luminance value (R _D , G _D , B _D ) of the color component of the depth cueing color are added and synthesized to obtain the color C (Rc, Gc, Bc) of the drawing pixel. ).

3. Processing of this Embodiment Next, an example of processing for realizing the method of this embodiment will be described with reference to FIGS. 7 and 8.

  First, as shown in FIG. 7, it is determined whether or not the timing of frame update (for example, 1/60 seconds) has arrived (step S1). If it is the frame update timing (Y in step S1), the shader program for the depth cueing process is transferred to the drawing processor (image generation unit 120) (step S2).

  Next, the shader parameters necessary for executing the shader program are set and transferred (step S3). Specifically, a matrix (world matrix and view matrix) for converting the vertex coordinates of the object to be drawn into the viewpoint coordinate system, the light source direction of the ambient light (parallel light source) in the viewpoint coordinate system, and the object color ( Color of decal texture mapped to object), distant view for setting depth cueing color, attenuation start point Sr and attenuation end point Gr for setting object color parameter PO, parameter PD for depth cueing color The increase start point Si and the increase end point Gi for setting are set as shading parameters and transferred to the drawing processor.

  Next, the vertex list (data including the local coordinates and texture coordinates of the vertex) of the object to be drawn is transferred to the drawing processor (step S4), and a command for instructing execution of the shader program is transferred to the drawing processor (step S4). S5).

  Subsequently, as shown in FIG. 8, the drawing processor acquires a shader program, shader parameters, and a vertex list (step S <b> 10), performs geometry calculation regarding the vertex of the object to be drawn, and from the virtual camera to the vertex. The depth value L, which is the distance of, is calculated (step S11). Specifically, the local coordinates of the vertices are subjected to matrix conversion to obtain the position of the vertex in the viewpoint coordinate system, and the distance from the virtual camera to the vertex in the viewpoint coordinate system is calculated to obtain the depth value L.

  Next, it is determined whether or not the sign of the difference value between the depth value L and the attenuation start point Sr is positive (step S12). If the depth value L is on the far side from the attenuation start point Sr (step S12). A process of attenuating the object color OC in accordance with the object color parameter PO is performed (Y in S12) (step S13).

  Next, it is determined whether or not the sign of the difference value between the depth value L and the increase start point Si is positive (step S14). If the depth value L is on the far side from the increase start point Si (step S14). In S14, Y), a process for obtaining the addition of the depth cueing color DC based on the depth cueing color parameter PD is performed (step S15).

  Then, the final output color C is obtained by addition synthesis of the object color OC and the depth cueing color DC, and is output to the drawing buffer (step S16).

4). Hardware Configuration Next, a hardware configuration capable of realizing the present embodiment will be described with reference to FIG. FIG. 18 is an example of a hardware configuration that can realize this embodiment.

  The main processor 900 operates based on a program stored in the optical disk 982 (CD, DVD, etc .: information storage medium), a program downloaded via the communication interface 990, a program stored in the ROM 950, or the like. Executes image processing, sound processing, and the like. The coprocessor 902 assists the processing of the main processor 900, and executes matrix operation (vector operation) at high speed. For example, when a matrix calculation process is required for a physical simulation for moving or moving an object, a program operating on the main processor 900 instructs (requests) the process to the coprocessor 902.

  The geometry processor 904 performs geometry processing such as coordinate conversion, perspective conversion, light source calculation, and curved surface generation based on an instruction from a program operating on the main processor 900, and executes matrix calculation at high speed. The data decompression processor 906 performs decoding processing of compressed image data and sound data, and accelerates the decoding processing of the main processor 900. Thereby, a moving image compressed by the MPEG method or the like can be displayed on the opening screen or the game screen.

  The drawing processor 910 executes drawing (rendering) processing of an object composed of primitive surfaces such as polygons and curved surfaces. When drawing an object, the main processor 900 uses the DMA controller 970 to pass the drawing data to the drawing processor 910 and, if necessary, transfers the texture to the texture storage unit 924. Then, the drawing processor 910 draws the object in the frame buffer 922 while performing hidden surface removal using a Z buffer or the like based on the drawing data and texture. The drawing processor 910 also performs α blending (translucent processing), depth cueing, mip mapping, fog processing, bilinear filtering, trilinear filtering, anti-aliasing, shading processing, and the like. When a programmable shader such as a vertex shader or a pixel shader is mounted on the rendering processor 910, creation / change (update) of vertex data and determination of a pixel (fragment) rendering color are performed according to the shader program. When an image for one frame is written in the frame buffer 922, the image is displayed on the display 912.

  The sound processor 930 includes a multi-channel ADPCM sound source and the like, generates game sounds such as BGM, sound effects, and sounds, and outputs them through the speaker 932. Data from the game controller 942 and the memory card 944 is input via the serial interface 940.

  The ROM 950 stores system programs and the like. In the case of an arcade game system, the ROM 950 functions as an information storage medium, and various programs are stored in the ROM 950. A hard disk may be used instead of the ROM 950. The RAM 960 is a work area for various processors. The DMA controller 970 controls DMA transfer between the processor and the memory. The optical disk drive 980 accesses an optical disk 982 in which programs, image data, sound data, and the like are stored. The communication interface 990 performs data transfer with the outside via a network (communication line, high-speed serial bus).

  The processing of each unit (each unit) in this embodiment may be realized entirely by hardware, or may be realized by a program stored in an information storage medium or a program distributed via a communication interface. May be. Alternatively, it may be realized by both hardware and a program.

  When the processing of each unit of this embodiment is realized by both hardware and a program, a program for causing the hardware (computer) to function as each unit of this embodiment is stored in the information storage medium. .

  More specifically, the program instructs the processors 902, 904, 906, 910, and 930, which are hardware, and passes data if necessary. Each processor 902, 904, 906, 910, 930 realizes the processing of each unit of the present invention based on the instruction and the passed data.

  Further, the present invention is not limited to the one described in the above embodiment, and various modifications can be made. For example, terms cited as broad or synonymous terms in the description in the specification or drawings can be replaced with broad or synonymous terms in other descriptions in the specification or drawings.

  Further, the parameter setting process, the depth cueing color setting process, and the synthesis process are not limited to those described in the present embodiment, and techniques equivalent to these are also included in the scope of the present invention.

  Further, the present invention can be applied to various games. The present invention is applied to various image generation 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, a system board for generating game images, and a mobile phone. Applicable.

The functional block diagram of the image generation system of this embodiment. The figure for demonstrating the conventional depth cueing method. The figure for demonstrating the depth cueing method of this embodiment. The figure for demonstrating the depth cueing method of this embodiment. The figure for demonstrating the depth cueing method of this embodiment. The figure for demonstrating the depth cueing method of this embodiment. The flowchart which shows the specific process example of this embodiment. The flowchart which shows the specific process example of this embodiment. Hardware configuration example

Explanation of symbols

100 processing unit,
110 Object space setting unit, 112 Movement / motion processing unit,
114 virtual camera control unit,
120 image generation units, 122 depth cueing processing units,
130 sound generator,
160 operation unit,
170 storage unit,
171 Main storage unit, 172 Drawing buffer, 173 Object data storage unit,
174 Texture storage unit, 176 Z buffer,
180 information storage medium, 190 display unit, 192 sound output unit,
194 Portable information storage device, 196 communication unit

Claims (10)

A program for generating an image visible from a virtual camera,
An object space setting section for setting an object in the object space;
A virtual camera control unit that sets the position and orientation of the virtual camera in the object space;
A depth cueing process for combining the object color and a given depth cueing color in association with the depth value of the object relative to the virtual camera when rendering the image of the object viewed from the virtual camera; Let the computer function as a depth cueing processor
The depth cueing processing unit
A first parameter having an attenuation characteristic with respect to the depth value is set as a color composition ratio of the object, and a second parameter having an increase characteristic with respect to the depth value is set as the composition ratio of the depth cueing color. Set as
Adjusting the color of the object based on the first parameter and adjusting the depth cueing color based on the second parameter;
A program characterized in that a color component of a drawing pixel is calculated by combining the adjusted object color and the adjusted depth cueing color . In claim 1,
The first start depth value indicating the depth value at which the attenuation adjustment of the color of the object is started is different from the second start depth value indicating the depth value at which the increase adjustment of the depth cueing color is started. ,
The first ending depth value indicating the depth value at which the color attenuation adjustment of the object ends is different from the second ending depth value indicating the depth value at which the depth cueing color increase adjustment ends. A program characterized by In claim 1 or 2,
The depth cueing processing unit
Of the colors attached to the celestial sphere object centered on the virtual camera in the object space as a distant view, the color attached to the intersection of the sight line direction of the virtual camera and the celestial sphere object is the depth cueing color. A program characterized by being set as In claim 1 or 2,
The depth cueing processing unit
By multiplying the color of the light source by a parameter that changes according to the angle difference between the visual line direction of the virtual camera and the direction of the light source from the virtual camera position toward the light source position set in the object space, A program characterized by setting a depth cueing color. In claim 1 or 2,
The depth cueing processing unit
The color in a predetermined direction in the object space with respect to the color of the given light source set in the object space and the direction of the light source from the virtual camera position toward the light source position set in the object space preparative, program and setting the depth cueing color by interpolating based on parameters that vary depending on the angular difference between the direction of said line of sight direction of the virtual camera source. In claim 2 ,
Said first start depth value, wherein the first end depth value, the second start depth value, and the at least one of the second ends depth values, weather set for the object space A program that is set based on at least one of the time to travel in the object space, the position of the virtual camera in the object space, and the orientation of the virtual camera in the object space.   In any one of Claims 1-6,
  A program characterized in that the first parameter is a value determined independently of the second parameter, and the second parameter is a value determined independently of the first parameter.   A computer-readable information storage medium, wherein the program according to any one of claims 1 to 7 is stored.   An image generation system for generating an image visible from a virtual camera,
  An object space setting section for setting an object in the object space;
  A virtual camera control unit that sets the position and orientation of the virtual camera in the object space;
  A depth cueing process for combining the object color and a given depth cueing color in association with the depth value of the object relative to the virtual camera when rendering the image of the object viewed from the virtual camera; A depth cueing processing unit,
  With
  The depth cueing processing unit
    A first parameter having an attenuation characteristic with respect to the depth value is set as a color composition ratio of the object, and a second parameter having an increase characteristic with respect to the depth value is set as the composition ratio of the depth cueing color. Set as
    Adjusting the color of the object based on the first parameter and adjusting the depth cueing color based on the second parameter;
    An image generation system comprising: combining the adjusted object color and the adjusted depth cueing color to calculate a color component of a drawing pixel.   The image generation system according to claim 9.
  The image generation system according to claim 1, wherein the first parameter is a value determined independently of the second parameter, and the second parameter is a value determined independently of the first parameter.

Images