Computer program, and image display method and image display system using the same

Abstract

To change an expression of a target region of a card-like object into a hologram sheet shape.SOLUTION: A computer program causes a prescribed computer to execute: a step of detecting a reference direction necessary for deciding color information of a target region 18 included in a card-like object used in a game on the basis of the output of a sensor of a user device; and a step of deciding color information of the target region in association with the reference direction such that an expression of the target region changes into a hologram sheet shape following a change in the detected reference direction. In the step of deciding color information, the color information is decided by referring to the incident direction and the sight line direction while changing at least one of the incident direction of light incident on the target region and the sight line direction of a user of the user device related to the target region in association with the reference direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a computer program for causing a change in the form of a hologram sheet with respect to the representation of an image of a card-like object. [Background technology]

[0002] Regarding the representation of card-like objects displayed on a game screen, attempts have been made to impart color changes in the form of hologram sheets similar to those seen on physical cards in the real world. For example, Patent Document 1 discloses a technology in which multiple sheets having white areas that simulate light reflection are prepared in advance so that their display modes are differentiated, and a sheet is appropriately selected according to the detected value of the tilt of the user's terminal device. The selected sheet is then superimposed on an image of a character or the like, thereby imparting a color change according to the tilt of the terminal device. Patent Document 2 discloses a technology in which the representation of the background of the card is changed to resemble a hologram sheet by changing the color of a color-changing image superimposed on the background of the card-like object according to a trigonometric function whose parameters include the attitude (tilt) of the terminal device and the display position within the image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5661835 [Patent Document 2] Patent No. 6723895 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional technology only produces a certain change in the representation of the background area, etc., depending on the position of the device. On the other hand, the appearance of the hologram sheet portion of a real card changes not only depending on the direction from which the user views it, but also depending on the amount of light hitting it. Conventional technology does not necessarily adequately represent changes depending on the amount of light hitting it, and there is room for improvement.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a computer program suitable for changing the representation of at least a partial area of ​​a card-shaped object into a hologram sheet. [Means for solving the problem]

[0006] A computer program according to one aspect of the present invention is a computer program for causing a specified computer to execute a process of displaying an image of a card-shaped object on a user device, and is configured to cause the computer to execute the following steps: detect a reference direction required to determine color information of a target area included in the object based on the output of a sensor of the user device; and determine the color information of the target area in association with the reference direction so that the representation of the target area changes in the form of a hologram sheet as the detected reference direction changes.In the step of determining the color information, the color information is determined by referring to the incident direction and the line of sight direction of the light incident on the target area, while changing at least one of the directions of the incident direction and the line of sight direction of the user of the user device relative to the target area in association with the reference direction.

[0007] Another aspect of the present invention is a computer program that causes a specified computer to execute a process of displaying an image of a card-shaped object on a user device, and is configured to cause the computer to execute the following steps: detecting a reference direction required to determine color information of a target area included in the object based on the output of a sensor of the user device; and determining the color information of the target area in association with the reference direction so that the representation of the target area changes in the form of a hologram sheet as the detected reference direction changes.In the step of determining the color information, the incident direction of light entering the target area is changed in association with the reference direction, and the color information is determined by referring to the incident direction.

[0008] An image display method according to one aspect of the present invention is an image display method that causes a specified computer to execute a process for displaying an image of a card-shaped object on a user device, and causes the computer to execute the steps of detecting the reference direction based on the output of a sensor of the user device and determining color information of the target area in accordance with the computer program of the above aspect.

[0009] An image display system according to one aspect of the present invention is an image display system that causes a specified computer to execute a process for displaying an image of a card-shaped object on a user device, and causes the computer to execute, in accordance with the computer program of the above aspect, a step of detecting the reference direction based on the output of a sensor of the user device, and a step of determining color information of the target area. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing an example of a game system including a game machine to which a computer program according to an embodiment of the present invention is applied; [Figure 2] FIG. 10 is a diagram showing an example of cards displayed on a game screen. [Figure 3] 3A and 3B are diagrams showing an example of changes in the background image of the card in FIG. 2. [Figure 4] FIG. 10 is a diagram showing an example of the relationship between a card and the line of sight and the incident direction of ambient light in a virtual three-dimensional space. [Figure 5] FIG. 10 is a diagram showing an example of changing the incident direction in response to a change in the attitude of the game machine. [Figure 6] FIG. 10 is a diagram showing an example of changing the line of sight direction in response to a change in the attitude of the game console. [Figure 7] 10A and 10B are diagrams showing an example of a case where the incident direction and the line of sight direction are changed in response to a change in the attitude of the game machine. [Figure 8] FIG. 10 is a diagram showing an example of changing the orientation of a card in a virtual three-dimensional space in response to a change in the attitude of a gaming machine. [Figure 9] FIG. 10 is a diagram illustrating an example of a method for expressing a background image in the form of a hologram sheet. [Figure 10] FIG. 2 is a diagram showing an example of the configuration of a control system of a game machine. [Figure 11] 11 is a flowchart showing an example of a process executed by the control unit of FIG. 10 to draw a background image. [Figure 12] FIG. 10 is a diagram showing an example of detecting the incident direction of ambient light in the real world using a camera in a game console. [Figure 13] FIG. 10 is a diagram showing an example of detecting the gaze direction of a user in the real world using a camera on a game console. [Figure 14] 10A and 10B are diagrams showing an example of bending and deforming a card in a virtual three-dimensional space in response to a user operation. DETAILED DESCRIPTION OF THE INVENTION

[0011] FIG. 1 shows an example of a game system according to an embodiment of the present invention. The game system 1 in FIG. 1 is an example of an image display system, configured as a network system including a game machine 2 and a server 3 capable of communicating with the game machine 2 via a predetermined network NT. The game machine 2 is an example of a user device to which the present invention is applied. The game machine 2 functions as a terminal device for the server 3, and allows a user to play a predetermined game by communicating with the server 3 or with another game machine 2 via the server 3. However, the game machine 2 may also be a standalone game machine that does not communicate with the server 3. In this case, the game machine 2 alone constitutes the game system.

[0012] The game console 2 includes a main body 4 and a pair of controllers 5A and 5B. The main body 4 executes various processes for providing a game, and the controllers 5A and 5B function as an example of input means that detects user operations and provides operation information to the main body 4. A monitor 6 serving as an example of output means or display means is integrally provided with the main body 4. Instead of or in addition to the monitor 6, a monitor separate from the game console 2 may be used to display the game screen. Each of the controllers 5A and 5B is provided integrally with or detachably attached to the main body 4, and functions as an example of input means for the game console 2 by being connected to the main body 4 via a wired or wireless connection. Hereinafter, the controller 5A and the controller 5B will be collectively referred to as the "controller 5," and may also be distinguished from each other by being referred to as the first controller 5A and the second controller 5B.

[0013] Each controller 5 is provided with an operation unit 7, such as a push button switch 7a and directional indicator keys 7b, as an operation unit operable by a user. Each controller 5 outputs a signal corresponding to the operation state of the operation unit 7 to the main body 4. Each controller 5 has a built-in gyro sensor 8, which is an example of a sensor that outputs a signal corresponding to the attitude (tilt) of the controller 5. The gyro sensor 8 outputs a signal corresponding to rotational movement (e.g., angular acceleration) around three orthogonal axes (Gx-axis, Gy-axis, and Gz-axis) set for the game console 2, as a signal indicating the attitude of the controller 5. The directions of the detection axes Gx, Gy, and Gz may be appropriately determined as long as they can detect changes in attitude in real space. For example, the normal direction to the screen of the monitor 6 may be set as the Gz-axis, and the directions of the short and long sides of the screen may be set as the Gx-axis and the Gy-axis, respectively. In this case, as seen from a user facing the game console 2, rotation around the Gx-axis corresponds to roll, rotation around the Gy-axis corresponds to pitch, and rotation around the Gz-axis corresponds to yaw.

[0014] The game machine 2 provides a user with a game using cards. FIG. 2 shows an example of a game screen displayed on the monitor 6 in the game. The game screen 10 in FIG. 2 is an example of a screen displayed when, for example, a user is allowed to view cards such as characters and items acquired by the user, like an illustrated book. The game screen 10 includes a list display section 12 in which icon images 11 symbolizing card characters, etc. are displayed in a matrix, and a card display section 15 in which a card image 14 of a character, etc. corresponding to an icon image 11 selected with a cursor 13 is displayed. In the list display section 12, the icon images 11 of characters, etc. that the user has acquired may be highlighted, while the icon images 11 of characters, etc. that the user has not yet acquired may be grayed out. In this way, the display manner of the icon images 11 may be differentiated depending on whether the user has acquired them. Alternatively, only the icon images 11 corresponding to characters, etc. acquired by the user may be displayed.

[0015] As shown enlarged in FIG. 3, the card image 14 further includes a main image 16 showing the appearance of a character, a frame image 17 decorating the card, and a background image 18. The frame image 17 further includes a character string and other information section 17a indicating the name of the character, the rank of the card, etc. The background image 18 enhances the decorativeness and dramatic effect of the card image 14. In this embodiment, the card image 14 is rendered such that the appearance of the background image 18 changes like a hologram sheet in association with changes in the posture detected by the gyro sensor 8. Therefore, the background image 18 corresponds to an example of a target area. Due to limitations in the representation of the drawing, FIG. 3(a) illustrates a case in which the background image 18 is rendered relatively bright, and FIG. 3(b) illustrates a case in which the background image 18 is rendered relatively dark. The change in the background image 18 is not limited to two stages, as shown in FIG. 3(a) and FIG. 3(b), but occurs continuously or steplessly in response to changes in the posture of the controller 5.

[0016] Changes in the background image 18 are made taking into account the direction from which the user observes (the line of sight) and the direction from which light strikes (the incident direction), just as with an actual physical hologram sheet. That is, the background image 18 is drawn by regarding at least one of the line of sight and the incident direction as having changed in relation to the attitude of the controller 5. Note that, because the two controllers 5A and 5B each have a built-in gyro sensor 8, the output of the gyro sensor 8 of either controller 5, for example, the first controller 5A, may be used as a reference for drawing the background image 18. When the controllers 5 are integrated with or attached to the main body 4, the output of the gyro sensor 8 of either controller 5 indicates the attitude of the game console 2. When the controllers 5 are separated from the main body 4, the output signal of the gyro sensor 8 of either controller 5 may be used as an output signal representative of the attitude of the game console 2. In other words, even if the attitude of the main body 4 remains unchanged, a change in the attitude of either of the controllers 5 is considered to be a change in the attitude of the game console 2. If the main body 4 has a built-in gyro sensor, the presentation of the background image 18 may be changed in association with the output signal of the gyro sensor. In any case, the gyro sensor that detects a change in direction that serves as a reference for changing the presentation of the background image 18 may be determined appropriately. In the following, the description will be continued assuming that the output of the gyro sensor 8 of either of the controllers 5 is an output that represents a change in the attitude of the game console 2.

[0017] Next, with reference to FIGS. 4 to 8, an example of a process for changing the representation of the background image 18 into a hologram sheet will be described. In the process of drawing the card image 14, the area of ​​the background image 18 and other areas (in the example of FIG. 3, the areas of the main image 16 and frame image 17) are identified separately. The background image 18 is drawn using a predetermined shader program for image processing, and the other areas are drawn using a predetermined texture image as is. As an example, the drawing of the main image 16, etc. may be processed so that the color information of the texture image of the shader program is used as is in the shader program. Alternatively, the main image 16 may be drawn in a separate process on a layer different from the drawing of the background image 18, and then superimposed on the background image 18. The following description will focus on the process for drawing the background image 18.

[0018] As shown in Figure 4, assume that a card 20 as an object corresponding to a card image 14 and a virtual camera 21 capturing an image of the card 20 are placed in a predetermined virtual three-dimensional space VS. A world coordinate system (Wx-Wy-Wz) is set as a three-axis Cartesian coordinate system in the virtual three-dimensional space VS, and an object coordinate system (Ox-Oy-Oz) is set as a three-axis Cartesian coordinate system in the card 20. The origin of each coordinate system and the direction of each axis may be determined as appropriate. In Figure 4, as an example, with respect to the object coordinate system, the Z axis is set in the normal direction of the card 20, and the X axis and Y axis are set in the directions of the short and long sides of the card 20, respectively.

[0019] The virtual camera 21 can be set at an appropriate position and in an appropriate direction. However, the card image 14 shown in FIGS. 2 and 3 is always displayed as an image facing the user, with its shape and size remaining constant, regardless of the attitude of the game machine 2. Therefore, in the example of FIG. 4, the virtual camera 21 is set to capture an image of the card 20 from the normal direction at a constant angle of view. In other words, the shooting direction C of the card 20 by the virtual camera 21 coincides with the normal direction of the card 20. As an example, the shooting optical axis of the virtual camera 21 is set to pass through the center of the card 20. The shooting optical axis does not necessarily have to be set to pass through the center of the card 20, as long as the entire surface of the card 20 can be included in the shooting range.

[0020] In the virtual three-dimensional space VS, the incident direction L of ambient light relative to the card 20 is also set. For example, assuming that light is irradiated toward the card 20 from a specific light source 22, the direction of that light is set as the incident direction L. Ambient light is light that strikes the card 20 and may be either natural light or illumination light. The light source 22 in FIG. 4 is depicted to indicate the direction of ambient light, and it is not necessary to place the light source 22 as a virtual object within the virtual three-dimensional space VS. For example, if the ambient light is parallel light such as sunlight, the light source 22 may be considered to be located at infinity in a specific direction. In this case, it is sufficient to set the incident direction L of the ambient light, and it is not necessary to place the light source 22 itself in the virtual three-dimensional space VS. This also applies to the light source 22 shown in FIGS. 5 to 8 and 14 described below. On the other hand, a lighting device that irradiates parallel light may be set as the light source 22 at a specific position within the virtual three-dimensional space VS. When setting uniformly spreading ambient light such as illumination light from a point light source, the position of the light source 22 must be determined. In setting the ambient light, various characteristics such as intensity (brightness), color temperature, wavelength distribution, etc. may be set in addition to the direction. These characteristics may be reflected in the rendering of the background image 18 as appropriate.

[0021] Next, with reference to FIG. 5, an example of the relationship between the attitude of the game machine 2 and the line of sight direction and incident direction with respect to the card 20 will be described. FIG. 5 shows an example of a case where the incident direction L of ambient light is changed in response to a change in the attitude of the game machine 2. In this example, it is assumed that the light source 22 changes direction in the virtual three-dimensional space in response to a change in the attitude of the game machine 2, and that the light source 22 moves from the position indicated by the imaginary line to the position indicated by the solid line as shown by arrow A. The card 20 is stationary. On the game screen 10 of FIG. 2, the card image 14 is always displayed facing forward, i.e., the card 20 is displayed as if observed from the front, so the virtual camera 21 is also stationary, just like the card 20. In other words, the relative positional relationship between the card 20 and the virtual camera 21 is unchanged.

[0022] 5, the user observes the card 20 from the same direction as the shooting direction C of the virtual camera 21. For example, it is assumed that the user's eye 23 is located at the position of the virtual camera 21 (the position of the imaging plane). Therefore, the user's line of sight E with respect to the card 20 coincides with the shooting direction C of the virtual camera 21, and the line of sight E with respect to the card 20 remains constant regardless of changes in the attitude of the game device 2. Therefore, the relationship between the card 20 and the incident direction L changes depending on the attitude of the game device 2.

[0023] The shader program for rendering background image 18 determines color information for each pixel of background image 18 using the user's line of sight E and the direction of incident ambient light L as parameters. In the example of FIG. 5, line of sight E remains constant relative to card 20, while the direction of incident ambient light L changes relative to card 20. Therefore, while displaying card image 14 on monitor 6 as if card 20 were observed from the front, it is possible to change the representation of background image 18 in the same way as when the way light hits card 20 changes. The appearance of a real hologram sheet varies in various ways depending on the direction from which it is observed and the direction from which light hits it. Even if the observation direction remains unchanged, the appearance also changes if the direction from which light hits it changes. In the example of FIG. 5, such changes can be reproduced.

[0024] In the example of FIG. 5, the light source 22, i.e., the incident direction L, changes in response to a change in the attitude of the game machine 2. However, the incident direction L with respect to the card 20 can be changed even if the card 20 and the virtual camera 21 are moved integrally in response to a change in the attitude of the game machine 2 while the light source 22 is stationary. In other words, whether the card 20 and the virtual camera 21 are stationary while the light source 22 is moved, or the card 20 and the virtual camera 21 are moved integrally while the light source 22 is stationary, the relative positional relationship between the card 20 and the virtual camera 21 and the light source 22 changes, and the incident direction L with respect to the card 20 changes. Note that in the example of FIG. 5, even if the card 20 and the virtual camera 21 are rotated relative to the light source 22 around an axis normal to the card 20, the incident direction L changes, and the appearance of the background image 18 changes. For example, if the gyro axis Gz in FIG. 1 is the normal direction of the monitor 6 and yaw motion around the gyro axis Gz corresponds to rotational motion around the normal direction of the card 20 in the virtual three-dimensional space, even if the gyro sensor 8 detects only yaw motion around the gyro axis Gz and not roll motion or pitch motion around the gyro axes Gx and Gy, the incident direction L relative to the card 20 will change, and the appearance of the background image 18 will change accordingly. A method for causing a hologram sheet-like change in the background image 18 depending on the viewing direction E and the incident direction L may be similar to processing using an existing shader program, and an example of this method will be described later. The shooting direction C and the viewing direction E strictly vary depending on the position of the card 20. However, if the difference is negligible, the shooting direction C and the viewing direction E may be considered to be constant throughout the entire area of ​​the card 20. However, the shooting direction C and the viewing direction E may also vary depending on the position of the card 20.

[0025] Fig. 6 shows an example in which the line of sight direction E is changed in response to a change in the attitude of the game machine 2. In the example of Fig. 6, the card 20 remains stationary regardless of a change in the attitude of the game machine 2, and the virtual camera 21 also remains stationary. Furthermore, while in the example of Fig. 5 the light source 22 moves within the virtual three-dimensional space, in the example of Fig. 6 the light source 22 also remains stationary, and the incident direction L of the ambient light relative to the card 20 remains constant.

[0026] On the other hand, in the example of FIG. 6 , it is assumed that the user's eyes 23 move within the virtual three-dimensional space as the attitude of the game console 2 changes. That is, a card image 14 captured by the virtual camera 21 from the normal direction of the card 20 is displayed on the monitor 6, but the direction from which the user observes the card image 14 displayed on the monitor 6 changes depending on the attitude of the game console 2. For example, it is assumed that the eyes 23 move from the imaginary line position to the solid line position as indicated by arrow A. Therefore, the gaze direction E that should be considered for rendering the background image 18 does not coincide with the shooting direction C of the virtual camera 21, but rather is a direction that changes relative to the card 20. This change in gaze direction E is reflected in the background image 18. In this example, it is possible to reproduce the change in appearance of a real hologram sheet when the direction of light incidence is constant and the observation direction changes. Note that in the example of FIG. 6 , even if the position of the eyes 23 remains unchanged and the card 20, virtual camera 21, and light source 22 move together as a unit as the attitude of the game console 2 changes, it is possible to change the gaze direction E relative to the card 20.

[0027] FIG. 7 shows an example in which both the line of sight E and the incident direction L with respect to the card 20 change in accordance with changes in the attitude of the game machine 2. In this example, too, the card 20 and the virtual camera 21 remain stationary regardless of changes in the attitude of the game machine 2. Meanwhile, it is assumed that the light source 22 and the user's eye 23 move in the virtual three-dimensional space in accordance with changes in the attitude of the game machine 2. For example, it is assumed that the light source 22 and the eye 23 move from the position indicated by the imaginary line to the position indicated by the solid line, as indicated by arrow A. In this case, the relationship between the line of sight E and the incident direction L remains constant regardless of changes in the attitude of the game machine 2, but both the line of sight E and the incident direction L change in unison with respect to the card 20. Therefore, changes in both the line of sight E and the incident direction L can be reflected in the representation of the background image 18.

[0028] FIG. 8 shows yet another example of the relationship between the attitude of the game machine 2 and the line-of-sight direction and incident direction with respect to the card 20. In the example of FIG. 8, the card 20 changes its orientation in the virtual three-dimensional space in response to a change in the attitude of the game machine 2, and the orientation of the card 20 as viewed from the virtual camera 21 also changes accordingly. As an example, an example of the card 20 before the change is shown by an imaginary line, and an example of the card 20 whose orientation has been changed as indicated by arrow A is shown by a solid line. Meanwhile, in the example of FIG. 8, the virtual camera 21 and light source 22 are assumed to be located at a fixed position and in a fixed orientation in the virtual three-dimensional space, regardless of the attitude of the game machine 2. The user's eyes 23 are also assumed to be located at the position of the virtual camera 21. Therefore, if the orientation of the card 20 changes, both the line-of-sight direction E with respect to the card 20 and the incident direction L of the ambient light change accordingly.

[0029] In the example of Fig. 8, it is not possible to display a card image 14 in which the card 20 is always viewed facing forward, as in the game screen 10 of Fig. 2. When the attitude of the game machine 2 is changed, an image is displayed in which the card 20 changes direction accordingly. Even in this case, since the line of sight direction E and incident direction L with respect to the card 20 change, it is possible to change the representation of the background image 18 to a hologram sheet in accordance with these changes.

[0030] Next, an example of a method for changing the representation of background image 18 in a hologram sheet in association with the line of sight and the incident direction will be described with reference to Fig. 9. Fig. 9 shows an example of information used to render background image 18. For example, a bump map 30 and color information 31 corresponding to the bump map 30 are used to render background image 18.

[0031] The bump map 30 is information that specifies the normal direction for each pixel of the background image 18. For example, the normal direction for any pixel Pij on the background image 18 is specified as a normal vector Nij (Xij, Yij, Zij) using values ​​in an appropriate coordinate system. The normal vector may be defined as a unit vector, for example, and the normal direction may be expressed hereinafter as being synonymous with the normal vector N. The normal vector N may be expressed according to the object coordinate system, for example, but may also be defined in any other coordinate system that is uniquely or inherently determined for the card 20. While FIG. 9 conveniently illustrates the differences in normal direction specified in the bump map 30 as a periodic shading pattern, the bump map 30 may be set appropriately as long as a normal vector suitable for generating a hologram sheet-like change in the background image 18 is set for each pixel. For example, the normal vector for each pixel of the bump map 30 is differentiated by regarding the surface of the card 20 as having minute irregularities similar to those of a hologram sheet. In other words, the bump map 30 artificially imparts to the card 20 minute irregularities similar to those of an actual hologram sheet.

[0032] The color information 31 is information for specifying the initial value of color information to be assigned to each pixel of the background image 18. The color information 31 includes, for example, a specular map 32, a diffuse map 33, and an emission map 34. The specular map 32 is information that specifies, on a pixel-by-pixel basis, color information for imparting a specular reflection effect to the background image 18, the diffuse map 33 is information that specifies color information for imparting a diffuse reflection effect to the background image 18, and the emission map 34 is information that specifies, on a pixel-by-pixel basis, color information for imparting an emission effect to the background image 18. For example, in the specular map 32, the RGB values ​​Rij, Gij, and Bij to be assigned to an arbitrary pixel Pij are specified as color information Cij for that pixel Pij. Color information may be specified in the other maps 33 and 4 in a similar manner.

[0033] As is clear from the relationship between the normal vector Nij at pixel Pij and the viewing direction E and incident direction L shown in Figure 9, even if the viewing direction E and incident direction L are constant with respect to the card 20, the viewing direction E and incident direction L differ for each pixel when the direction of the normal vector N of each pixel is used as a reference. The shader that renders the background image 18 corrects the color information specified in the color information 31 for each pixel according to a calculation rule (function) that incorporates the normal vector N, viewing direction E, and incident direction L of each pixel as parameters, and determines the final color information for each pixel based on the calculation result. Through this processing, the color information of each pixel of the background image 18 varies in various ways depending on the normal vector N, viewing direction E, and incident direction L, relative to the initial value specified in the color information 31. This allows an expression to be displayed on the background image 18 like a hologram sheet. Moreover, at least one of the viewing direction E and incident direction L changes depending on the orientation of the game console 2, as illustrated above. Therefore, when the attitude of the game device 2 is changed, the appearance of the background image 18 also changes as if the line of sight or the direction of incident light had changed, making it possible to change the appearance of the background image 18 in the same way as with an actual hologram sheet.

[0034] Next, an example of the control system of the game machine 2 and its processing will be described, focusing on the portion related to drawing the card image 14. FIG. 10 shows an example of a schematic configuration of the control system of the game machine 2. The game machine 2 includes a control unit 50 and a storage unit 51. The control unit 50 is configured as a computer including a CPU and a GPU as microprocessors and internal storage devices required for their operation, such as cache memory, RAM, and frame memory. The storage unit 51 is a storage device that uses a non-volatile storage medium such as a magnetic storage medium or flash memory and functions as an external storage device for the control unit 50. The operation units 7, gyro sensors 8, and monitor 6 of the controllers 5A and 5B are connected to the control unit 50. The control unit 50 may further include a sound source control unit, a network control unit, etc.

[0035] The storage unit 51 stores a game program Pg, game data Dg, and play data Dp for providing a game. The game program Pg is an application program that causes the control unit 50 to execute various arithmetic processes and operational controls required for the game in cooperation with an operating system that controls the basic operations of the control unit 50 or an image drawing program pre-installed in the control unit 50 to cause the GPU to execute image drawing processes. The game program Pg further includes a game processing program Pg1 and an image processing program Pg2. The game processing program Pg1 is a computer program that causes the control unit 50 to execute various processes required for progressing a game provided by the game machine 2 in accordance with a user's selection. The image processing program Pg2 is a computer program that draws images corresponding to the progress of the game and displays them on the monitor 6. A shader program for drawing the card images 14 described above also constitutes part of the image processing program Pg2.

[0036] The game data Dg is data to be referenced as appropriate in controlling the game. The game data Dg may include various data necessary for rendering the card images 14, such as the bump map 30 and color information 31 shown in FIG. 9 , as well as various texture data such as the main image 16 and frame image 17 to be expressed in the card images 14. The play data Dp is data for each user associated with the game play by the user of the game machine 2. For example, information such as the user's play history and status may be included in the play data Dp. The game program Pg and game data Dg are distributed from the server 3 to the game machine 2 as appropriate and stored in the storage unit 51. However, these data may also be provided via a storage medium readable by the game machine 2.

[0037] When the control unit 50 reads the game program Pg, the control unit 50 is provided with a game processing unit 52 and an image processing unit 53. The game processing unit 52 is a logical device realized by the CPU of the control unit 50 cooperating with the game processing program Pg1, and the image processing unit 53 is a logical device realized by the GPU of the control unit 50 cooperating with the image processing program Pg2. The game processing unit 52 controls the game in accordance with the game processing program Pg1. The image processing unit 53 executes processing for rendering an image corresponding to the progress of the game by the game processing unit 52 and displaying the image on the monitor 6. Note that if a computer program for causing the GPU of the control unit 50 to execute general-purpose image processing for rendering images of three-dimensional objects, such as a general-purpose shader program, is pre-installed in the game machine 2, the image processing program Pg2 may be configured to cooperate with the general-purpose computer program to realize the image processing unit 53.

[0038] FIG. 11 shows an example of a processing procedure executed by the control unit 50 of the game machine 2 to draw the background image 18. This example is an example of processing when, as shown in FIG. 5, the incident direction L is changed in response to a change in the attitude of the game machine 2, and the background image 18 is drawn while the line of sight direction E with respect to the card 20 remains unchanged. When the game being played on the game machine 2 is in a state in which the card image 14 is to be displayed, the processing of FIG. 11 is started to draw the background image 18. When the processing of FIG. 11 is started, the game processing unit 52 first detects and sets the current attitude of the game machine 2 based on the output of the gyro sensor 8 (step S11). The attitude of the game machine 2 may be detected as the difference between the output of the gyro sensor 8 in the initial attitude and the current output of the gyro sensor 8, with the state in which the game machine 2 is in a specific attitude being defined as the initial attitude. For example, the initial attitude may be the attitude of the game machine 2 at the time when display of the card image 14 begins, but is not limited thereto. Alternatively, the initial attitude may be the attitude of the game machine 2 at the time when the game is started or when the game transitions to a specific mode. The attitude detected in step S11 indicates the direction in which the game device 2 is located, and this direction corresponds to an example of the reference direction required to determine the color information of the background image 18.

[0039] Next, the game processing unit 52 sets the card 20 in the virtual three-dimensional space (step S12). As an example, the game processing unit 52 places the card 20 as a polygon model at a predetermined position in the virtual three-dimensional space. Furthermore, the game processing unit 52 sets textures such as the bump map 30 and color information 31 prepared for drawing the background image 18 (step S13), and then sets a shader for drawing the background image 18 (step S14). In this case, the shader may be a programmable shader programmed for drawing the background image 18, and may be provided to the control unit 50 as part of the image processing program Pg2. After completing the processing of step S14, the game processing unit 52 passes the information set in steps S11 to S14 to the image processing unit 53 as information for drawing the background image 18, and starts drawing the background image 18 (step S15). Thereafter, the game processing unit 52 ends the processing of FIG. 11.

[0040] Meanwhile, the image processing unit 53 starts the processing of FIG. 11 in response to the processing of step S15. Based on information provided by the game processing unit 52, the image processing unit 53 first sequentially executes vertex shader processing in step S21, pixel shader processing in step S22, and post-effect processing in step S23 to draw the background image 18. Furthermore, the image processing unit 53 adds other images from the game screen 10 to draw a final image and displays it on the monitor 6. The vertex shader processing converts the coordinates of each vertex of a polygon constituting the card 20 in a virtual three-dimensional space into a two-dimensional screen coordinate system. The pixel shader processing determines color information for each pixel in the screen coordinate system. The post-effect processing further corrects the color information for each pixel in accordance with predetermined conditions. These processes may be performed in the same manner as a general shader program. However, the processing of the background image 18 includes processing based on the normal direction of each pixel, the line of sight, and the incident direction of ambient light, and the incident direction reflects changes in the attitude of the game console 2. An example of the processing contents is shown in FIG. 11, but the main points will be explained below.

[0041] First, in the vertex shader process of step S21, the incident direction of ambient light relative to the card 20 is determined according to the attitude of the game machine 2 set in step S11, in other words, the reference direction detected based on the output of the gyro sensor 8. However, the quantitative (angular) correspondence between the change in the reference direction and the change in the incident direction does not necessarily need to be set one-to-one. For example, if the rotation angle detected by the gyro sensor 8 around a predetermined gyro axis is X°, the angle by which the incident direction changes around the same axis is doubled to 2X°. In this case, the change in the incident direction may be increased by a fixed ratio relative to the change in the reference direction. In this case, the degree of change in the background image 18 relative to the change in the attitude of the game machine 2 is increased, thereby making the change in the hologram sheet more noticeable to the user. However, the change in the incident direction may also be reduced by a fixed ratio relative to the change in the reference direction. Such a reduction relationship may be set when, for example, a one-to-one relationship would result in an unnaturally large change in the background image 18 relative to the change in the attitude of the game machine 2.

[0042] The vertex shader process also involves placing the polygon model of card 20 set in step S12 in a virtual three-dimensional space and converting the vertex coordinates of each polygon in the virtual three-dimensional space into coordinate values ​​in a two-dimensional screen coordinate system corresponding to the imaging plane of the virtual camera. In the example of Figure 5, virtual camera 21 is placed so as to photograph card 20 from the normal direction, and the positional relationship between card 20 and virtual camera 21 is constant. Therefore, regardless of the position and orientation of card 20 in the virtual three-dimensional space, the vertex coordinates of each polygon in the screen coordinate system after coordinate conversion are constant.

[0043] As described above, if the ambient light incident on the card 20 is parallel light, the incident direction can be uniquely determined from the reference direction determined based on the output of the gyro sensor 8, without having to place a light source 22 in the virtual three-dimensional space to determine the incident direction. Furthermore, the correspondence between the card 20 and the virtual camera 21 is also constant. Therefore, it is possible to omit the vertex shader process and directly determine the vertex coordinates of each polygon in the screen coordinate system, thereby determining the coordinates in the bump map 30 and color information 31. However, shader programs are generally configured to place a polygon model in the virtual three-dimensional space, perform vertex shader processing to convert the three-dimensional coordinates of each polygon vertex into two-dimensional coordinates in the screen coordinate system, and then perform pixel shader processing using the results of this processing. Therefore, if the polygon model of the card 20 is temporarily placed in the virtual three-dimensional space and the vertex coordinates in the screen coordinate system are determined, existing programmable shaders can be applied, which is convenient. As shown in FIG. 8, when changing the positional relationship between the card 20 and the virtual camera 21 in the virtual three-dimensional space, coordinate conversion processing using the vertex shader process is required.

[0044] In the pixel shader processing of step S22, as an example, the final color of each pixel on the background image 18 is determined through specular processing, diffuse processing, and emission processing. In this processing, calculations are performed using as parameters the normal vector N of each pixel specified in the bump map 30, the incident direction L of the ambient light relative to the card 20, and the line of sight E. Note that the incident direction L and line of sight E are expressed as unit vectors having those directions and incorporated into the calculations. In the following, the incident direction L and line of sight E will both refer to vectors.

[0045] Specular processing is a process that calculates the effect of specular reflection on the card 20 on the color information of each pixel in the background image 18. For example, a half vector H is calculated by adding the incident direction L and the line of sight direction E. Next, the strength of the specular reflection at each pixel is calculated by raising a predetermined multiplier a to the inner product (N·H) of each pixel's normal vector N and the half vector H. Furthermore, the specular Sp, which is color information that takes into account the specular (specular reflection) of each pixel, is calculated by multiplying the specular color and intensity. For example, the specular color may be the color information of each pixel specified by the specular map 32. In this process, the smaller the deviation between the line of sight direction E and the incident direction L and the deviation between these directions and the normal vector N, the greater the strength of the specular reflection. As a result, the specular Sp changes toward white, or in other words, becomes brighter. If the direction in which card 20 is observed from the front is the normal direction of card 20 as a whole, the smaller the deviation of the incident direction L and the line of sight E from that normal direction, the brighter the background image 18 will be due to specular reflection, while the strength of the specular reflection will vary depending on the deviation of the incident direction L and the line of sight E from the normal vector N of each pixel.

[0046] Diffuse processing is a process that calculates the effect of diffuse light generated by reflection on the card 20 on the color information of each pixel of the background image 18. For example, the intensity of diffuse light at each pixel is calculated by taking the dot product of the incident direction L and the normal vector N of each pixel. Next, diffuse Df, which is color information that takes into account the diffusion (diffuse reflection) of each pixel, is calculated by multiplying the diffuse color and intensity. As an example, the diffuse color may be the color information of each pixel specified by the diffuse map 33. In this process, the smaller the deviation between the incident direction L and the normal vector N, the greater the intensity of diffuse reflection. As a result, the diffuse Df changes toward white, or in other words, becomes brighter. In other words, the intensity of diffuse reflection varies depending on the deviation between the incident direction L and the normal vector N of each pixel.

[0047] Emission processing is processing for further correcting the color information of the background image 18. When it is necessary to appropriately correct the color information obtained by specular processing and diffuse processing, such as by uniformly increasing the brightness of at least a portion of the background image 18, the emission color specified in the emission map 34 is set as the amount of correction as the emission Em. For example, when the specular processing and diffuse processing are used to reproduce a backlit situation on the card 20, that is, when ambient light strikes the card 20 from behind, reflection on the card 20 is almost eliminated, and the background image 18 may be rendered uniformly black or a dark color close to black. In such a case, emission Em may be set to increase the overall brightness. Other processing may be applied, such as correcting the color information so that the brightness of the background image 18 does not exceed an upper or lower limit. However, emission Em may be omitted.

[0048] In pixel shader processing, the specular (Sp), diffuse (Df), and emission (Em) calculated as described above are added together to calculate the final color information for each pixel. The resulting color information is obtained by modifying the color information for each pixel of the background image 18 by referring to specular reflection and diffuse reflection as parameters, which correspond to the relationship between the incident direction (L) and the line of sight (E) of each pixel and the normal vector (N) of that pixel. Therefore, by modifying the normal vector (N) of each pixel specified in the bump map 30 in accordance with the minute irregularities of an actual hologram sheet, a color distribution similar to that of a hologram sheet can be expressed. Furthermore, by changing the incident direction (L) in response to changes in the attitude of the game console 2, it is possible to express the background image 18 changing in response to the direction of light, similar to that of a hologram sheet.

[0049] The post-effect processing in step S23 is performed to add further visual effects to the final color of each pixel of the background image 18 determined by the pixel shader processing. For example, pixels that satisfy a specific condition, such as pixels whose luminance is equal to or greater than a predetermined brightness, may be extracted, and the color information of the extracted pixels may be corrected to produce a blurring effect. However, the post-effect processing may also be omitted as appropriate.

[0050] In the above, the processing of FIG. 11 is applied to the example of FIG. 5, i.e., the case where the incident direction L is changed in response to a change in the attitude of the game machine 2. However, the processing of FIG. 11 may also be applied to the examples of FIG. 6, FIG. 7, or FIG. 8. That is, the example of FIG. 6 can be realized by changing the line of sight E in response to a change in the attitude of the game machine 2, and the example of FIG. 7 can be realized by changing both the line of sight E and the incident direction L. Furthermore, the example of FIG. 8 can be realized by moving the card 20 and the virtual camera 21 in the virtual three-dimensional space in response to a change in the attitude of the game machine 2.

[0051] The present invention is not limited to the above-described embodiment and may be embodied in various modified or altered forms. For example, when an image of the card 20 photographed while always facing the camera head-on is displayed as the card image 14 as described above, it is not necessary to arrange the card 20 as a polygon model in a virtual three-dimensional space and convert the three-dimensional vertex coordinates of each polygon into the screen coordinate system of the virtual camera 21. Furthermore, the coordinates of each position of the card 20 projected onto the screen coordinate system can be identified without such coordinate conversion, and the correspondence with the coordinates of the bump map 30 and the color information 31 is also uniquely determined. Furthermore, the correspondence between changes in the attitude of the game machine 2 and the incident direction L or the line of sight E can also be identified without necessarily constructing a scene in the virtual three-dimensional space. Therefore, it is also possible to arrange the card 20 in a two-dimensional screen coordinate system and perform the processes from step S22 onward.

[0052] On the other hand, the process in Figure 11 illustrates only the process required to draw the background image 18 portion of the card image 14, and other images such as the main image 16 may be drawn using any suitable method. When performing a process such as shading at least a portion of the main image 16 or frame image 17, a suitable shader program may be prepared, and the processes may be performed in any suitable order before and after the process in Figure 11. Furthermore, when a portion of the main image 16 or the like is changed into a hologram sheet like the background image 18, the process in Figure 11 may also be applied to that portion. Even when the main image 16, frame image 17, and background image 18 are drawn using separate processes, the order of the processes does not matter as long as a Z-buffer is used, and it is not necessary to process the images in the background first.

[0053] The processing contents of the image processing unit 53 shown in Figure 11 are just an example, and may be changed as appropriate as long as at least one of the incident direction L and the line of sight direction E is changed in accordance with a change in the attitude of the game machine 2, and the change causes a hologram sheet-like change in the representation of the background image 18.

[0054] 11, color information is determined in the pixel shader processing by taking into account both the incident direction L and the line of sight direction E as parameters. However, as long as changes in the incident direction L are reflected in the representation of the background image 18, a simpler process may be applied in which the line of sight direction E is not considered as a parameter and the color information of each pixel is determined from the relationship between the incident direction L and the normal vector N. Even in this case, it is possible to reflect changes in the relationship between the normal vector N and the incident direction L in the representation of the background image 18, thereby representing changes in the background image 18 corresponding to changes in the direction in which light strikes. That is, a reference direction required for determining the color information of the background image 18 may be detected based on the output of a sensor in the game machine 2, and the incident direction L may be changed in relation to the detected reference direction, and the color information of each pixel may be determined by referring to the incident direction as a parameter so that the representation of the background image 18 changes like a hologram sheet.

[0055] In the above embodiment, the reference direction is detected using the output of the gyro sensor 8, and at least one of the incident direction L and the line of sight direction E is changed in response to a change in the reference direction. However, the sensor used to detect the reference direction is not limited to the example using the gyro sensor 8. Any sensor capable of outputting a signal containing directional information can be used appropriately to detect the reference direction. Furthermore, the reference direction is not limited to the example in which it is set in association with the attitude of the game machine 2. The reference direction may be any direction that changes so as to change the representation of the background image 18 and may serve as a reference for identifying the incident direction L or the line of sight direction E, and does not necessarily have to be a direction that represents the attitude of the game machine 2.

[0056] For example, as shown in FIG. 12 , a camera 60 provided in the game machine 2 may be used to capture an image of the external world around the user, and the incident direction Lr of ambient light from a light source (including the sun) 61 in the real world may be detected from the obtained image, and the incident direction L with respect to the card 20 may be determined using this as a reference direction. In this case, the camera 60 functions as an example of a sensor for detecting the reference direction. If the direction of ambient light in the real world is detected as the reference direction, changes in this direction can be reflected in changes in the incident direction L with respect to the card 20. This makes it possible to change the appearance of the background image 18 in accordance with changes in the direction of ambient light around the game machine 2.

[0057] The detection of the real incident direction Lr is not limited to the camera 60, and any device capable of obtaining a signal correlated with the incident direction Lr may be used. For example, when detecting the brightness of the real world surrounding the game console 2 using a brightness sensor, the incident direction Lr in the real world can be determined based on the change in brightness. Multiple brightness sensors may be provided in the game console 2 so that output differences occur depending on the incident direction Lr, and the incident direction Lr may be detected based on the outputs of these brightness sensors. For example, by arranging multiple brightness sensors with differentiated sensitivity directions, the incident direction Lr can be determined based on the difference in brightness detected by each sensor. Note that the light source 61 is shown in FIG. 12 for convenience. The light source 61 does not necessarily need to be included in the shooting range PA of the camera 60.

[0058] Regarding the gaze direction E, as shown in FIG. 13 , the position of the user's real eyes 62 may be determined from the image captured by the camera 60, and the user's real gaze direction Er may be detected from the determination result. The gaze direction E relative to the card 20 may be determined using this as a reference direction. In this case, the camera 60 also functions as an example of a sensor used to detect the reference direction. The method of determining the gaze direction E relative to the card 20 based on the real gaze direction Er is applicable when the gaze direction E relative to the card 20 is changed relative to the card 20, as shown in FIG. 6 . In this case, the real gaze direction Er can be reflected in the gaze direction E relative to the card 20. Furthermore, the real incident direction Lr captured by the camera 60 may also be detected as a reference direction, and the incident direction L and gaze direction E relative to the card 20 may be changed in association with changes in the real incident direction Lr and gaze direction Er. This method can be suitably used when both the incident direction L and gaze direction E are changed in response to changes in the attitude of the game machine 2, as in the example of FIG. 7 . The incident direction L and gaze direction E can be reflected in the real-world incident direction Lr and gaze direction Er. The position of the user's real eyes 62 can be determined by any known method.

[0059] In the above embodiment, the card 20 is assumed to be a flat object. However, the card 20 may be bent in accordance with the orientation of the controller 5. For example, in the game machine 2 of FIG. 1 , if the controllers 5A and 5B are detachable from the main body 4, the controllers 5A and 5B may assume different orientations. Therefore, for example, if the first controller 5A on the left side is tilted leftward and the second controller 5B on the right side is tilted rightward, this may be considered a bending operation of the card 20, and the left and right sides of the card 20 may be bent as shown in FIG. 14 . In this case, by changing the normal vector N specified in the bump map 30 in accordance with the degree of bending of the card 20, the incident direction L and the viewing direction E can be relatively changed in accordance with the bending of the card 20, and the appearance of the background image 18 can be changed in accordance with these changes. Note that FIG. 14 illustrates an example in which the left and right ends of the card 20 are bent downward. However, if the controllers 5A and 5B are tilted in the opposite direction, the left and right ends of the card 20 may be displaced upward. Furthermore, when the controllers 5A and 5B are tilted forward or backward, respectively, it is possible to bend and deform the upper and lower ends of the card 20.

[0060] In the above embodiment, the representation of the background image 18 of the card image 14 is changed to a hologram sheet-like form, but the target area to which the hologram sheet-like representation is applied according to the present invention is not limited to the background image 18. Any appropriate area of ​​a card-like object may be set as the target area. The card-like object is not limited to cards used in games. The present invention is applicable to applications in which at least a portion of various card-like objects is set as the target area and the representation thereof is changed to a hologram sheet-like form.

[0061] The user device in the present invention is not limited to a game console, but may be any device operated by a user, such as a smartphone, tablet, or mobile PC. Furthermore, the present invention may involve causing a computer other than the user device to execute processing and displaying an image corresponding to the processing result on the user device. For example, the user device may function as a remote input / output terminal device for another computer, such as a server or a remotely accessed computer, and the other computer may execute processing for drawing a card-shaped object and display the processing result on the user device.

[0062] Various aspects of the present invention derived from the above-described embodiments and modifications will be described below. In the following description, corresponding components shown in the accompanying drawings will be written in parentheses to facilitate understanding of each aspect of the present invention, but the present invention is not limited to the illustrated forms.

[0063] A computer program according to one aspect of the present invention is a computer program (Pg) for causing a predetermined computer (50) to execute a process of displaying an image (14) of a card-shaped object (20) on a user device (2), and is configured to cause the computer to execute the following steps: a step (S11) of detecting a reference direction (for example, a direction indicating the attitude of the game console 2) required to determine color information of a target area included in the object based on the output of a sensor (8; 60) of the user device; and a step (S21-S23) of determining color information of the target area in association with the reference direction so that the representation of the target area changes in the form of a hologram sheet as the detected reference direction changes. In the step of determining color information, the color information is determined by referring to the incident direction (L) of light incident on the target area and the line-of-sight direction (E) of the user of the user device relative to the target area, while changing at least one of the direction in association with the reference direction.

[0064] According to the above aspect, by referring to the incident direction and the line of sight direction when determining the color information of the target area, the direction from which light strikes the object and the direction from which the object is being observed can be reflected in the representation of the target area. Moreover, by changing at least one of the incident direction and the line of sight direction in association with a change in the reference direction detected based on the output of the sensor in the user device, the representation of the target area can be varied in a variety of ways depending on the direction from which light strikes and the direction from which the object is being observed, just like a real hologram sheet.

[0065] In the above aspect, in the step of determining the color information, the color information may be determined by changing the incident direction in accordance with the reference direction while maintaining the line of sight constant (see FIG. 5 for an example). Alternatively, in the step of determining the color information, the line of sight may be determined in accordance with the reference direction while maintaining the incident direction in accordance with the reference direction (see FIG. 6 for an example). Furthermore, in the step of determining the color information, the color information may be determined while changing each of the line of sight and the incident direction in accordance with the reference direction (see FIG. 7 for an example). In either case, it is possible to change the representation of the target area on a hologram sheet by changing either the incident direction or the line of sight direction of light with respect to the target area of ​​an object, or both, in association with a change in the reference direction detected using a sensor in a user device.

[0066] In the above aspect, the step of determining the color information may include determining the normal direction of each pixel based on information in a bump map (30) that describes the normal direction (N) of each pixel when the target area is defined as a set of multiple pixels, and determining the color information of each pixel so that the color information changes depending on the relationship between the determined normal direction and the incident direction and the line of sight. In this way, by varying the normal direction of each pixel using the bump map information, it is possible to impart pseudo-unevenness to the target area and appropriately change the color information depending on the relationship between the normal direction and the light incident direction and the line of sight direction.

[0067] A computer program according to another aspect of the present invention is a computer program (Pg) that causes a predetermined computer (50) to execute a process of displaying an image (14) of a card-like object (20) on a user device (2), and is configured to cause the computer to execute the following steps: a step (S11) of detecting a reference direction (for example, a direction indicating the attitude of the game console 2) required to determine color information of a target area included in the object based on the output of a sensor (8; 60) of the user device; and a step (S21-S23) of determining color information of the target area in association with the reference direction so that the representation of the target area changes in the form of a hologram sheet as the detected reference direction changes. In the step of determining color information, the incident direction (L) of light incident on the target area is changed in association with the reference direction, and the color information is determined by referring to the incident direction.

[0068] According to the above aspect, by referring to the incident direction when determining the color information of the target area, the direction from which light is hitting the object can be reflected in the representation of the target area. Moreover, by changing the incident direction in association with changes in the reference direction detected based on the output of the sensor of the user device, the representation of the target area can be varied in a variety of ways depending on the direction from which light hits, just like a real hologram sheet.

[0069] In each of the above aspects, the object may be a card to be displayed in a game played on the user device. In this case, the target area may be at least a portion of the background of the card. By changing the representation of at least a portion of the card used in the game, and even at least a portion of the card's background, to a hologram sheet, the decorativeness and presentation of the card can be enhanced, increasing the user's desire to own or acquire the card and ultimately increasing the enjoyment of the game.

[0070] In each of the above aspects, the sensor may output a signal corresponding to the posture of the user device, thereby enabling the representation of the target area of ​​the object to be changed in the form of a hologram sheet in response to changes in the posture of the user device.

[0071] The computer program according to one aspect of the present invention may be provided in a state stored in a storage medium. By using this storage medium, for example, the computer program according to the present invention can be installed on a computer and executed, thereby realizing the system of the present invention using the computer. The storage medium storing the computer program may be a non-transitory storage medium such as a CD-ROM.

[0072] The present invention may be configured as an image display method for causing a predetermined computer (50) to execute a process for displaying an image (14) of a card-like object (20) on a user device (2), the image display method including causing the computer to execute a step (S11) of detecting the reference direction based on an output of a sensor (8) of the user device and steps (S21-S23) of determining color information of the target area in accordance with the computer program (Pg) of the above-described embodiment. Also, the present invention may be configured as an image display system (1) for causing a predetermined computer (50) to execute a process for displaying an image (14) of a card-like object (20) on a user device (2), the image display system including causing the computer to execute a step (S11) of detecting the reference direction based on an output of a sensor (8) of the user device and steps (S21-S23) of determining color information of the target area in accordance with the computer program (Pg) of the above-described embodiment. According to these image display methods and systems, it is possible to change the representation of at least a partial area of ​​a card-like object into a hologram sheet-like representation in accordance with the computer program of the above aspect. [Explanation of symbols]

[0073] 1 Game system (image display system) 2. Game consoles (user devices) 8 Gyro Sensor 14 Card Images 18 Background image (target area) 20 Cards (Objects) 30 Bump Maps 50 Control Unit 60 cameras E View direction L Incident direction N normal vector (normal direction)

Claims

1. A computer program for causing a predetermined computer to execute a process of displaying an image of a card-like object on a user device, detecting a reference direction necessary for determining color information of a target region included in the object based on an output of a sensor of the user device; determining color information of the target area in relation to the reference direction such that the representation of the target area changes on the hologram sheet as the detected reference direction changes; In the step of determining the color information, a computer program is provided which determines the color information by referring to an incident direction and a line-of-sight direction, while changing at least one of the incident direction, which is virtually set as the direction of light incident on the target area, and the line-of-sight direction, which is virtually set as the direction in which a user of the user device observes the target area, in relation to the reference direction.

2. The computer program according to claim 1 , wherein the step of determining the color information determines the color information by changing the incident direction according to the reference direction while keeping the line of sight direction constant.

3. The computer program according to claim 1 , wherein the step of determining the color information determines the color information by changing the line of sight direction in accordance with the reference direction while keeping the incident direction constant.

4. The computer program according to claim 1 , wherein in the step of determining the color information, the color information is determined while changing each of the incident direction and the line of sight direction in accordance with the reference direction.

5. The computer program according to any one of claims 1 to 4, wherein the step of determining the color information determines the normal direction of each pixel based on bump map information that describes the normal direction of each pixel when the target area is defined as a collection of multiple pixels, and determines the color information of each pixel so that the color information changes depending on the relationship between the determined normal direction and the incident direction and the line of sight direction.

6. A computer program that causes a predetermined computer to execute a process of displaying an image of a card-like object on a user device, detecting a reference direction necessary for determining color information of a target region included in the object based on an output of a sensor of the user device; determining color information of the target area in relation to the reference direction such that the representation of the target area changes on the hologram sheet as the detected reference direction changes; A computer program, in which in the step of determining the color information, an incident direction that is virtually set as the direction of light incident on the target area is changed in relation to the reference direction, and the color information is determined by referring to the incident direction.

7. The computer program according to any one of claims 1 to 6, wherein the object is a card to be displayed in a game played on the user device.

8. The computer program of claim 7 , wherein the target area is at least a portion of the background of the card.

9. The computer program according to any one of claims 1 to 8, wherein the sensor outputs a signal according to the attitude of the user device.

10. An image display method for causing a predetermined computer to execute a process for displaying an image of a card-like object on a user device, comprising: An image display method that causes a computer to execute the steps of: detecting the reference direction based on the output of a sensor of the user device; and determining color information of the target area in accordance with the computer program of any one of claims 1 to 9.

11. An image display system that causes a predetermined computer to execute a process of displaying an image of a card-like object on a user device, An image display system that causes a computer to execute the steps of detecting the reference direction based on the output of a sensor of the user device and determining color information of the target area in accordance with the computer program of any one of claims 1 to 9.

Images