JP2007304727A - Program, information storage medium, and image generation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the precision of a Z value stored in a Z buffer, and to prevent any unsuitable image from being generated since the front-to-back position relationship of an object is not accurately discriminated. <P>SOLUTION: A Z value application range including a position Pp of its own vehicle PC as an object is set within a range from the position P0 of a replay camera CM to a plotting farthest position P1. A deep side position P3 between the both end positions of the Z value application range is set as the plotting farthest position P1, and a front side position P2 is set based on the replay camera CM. That is, a distance L2 to be acquired by multiplying a distance Lp from the position P0 of the replay camera CM to the position Pp of its own vehicle by a coefficient k to be decided based on a field angle ψ and a depression angle θ of the reply camera CM is set as a distance to the front side position P2. Then, the Z value is applied to the set Z value application range, and hidden surface erasure processing within the Z value application range based on the replay camera CM is performed so that a replay image can be generated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image generation apparatus that generates an image of a virtual space viewed from a virtual camera based on a Z buffer method.

  Conventionally, in a game device which is a kind of image generation device, an object such as a player character is arranged in a game space which is a virtual space, a viewpoint (virtual camera) is set, and an image of the game space generated based on this viewpoint is displayed. Displayed as a game image.

In the game device, one game image (frame image) is generated and displayed every predetermined frame time. When there are a large number of objects in the field of view or an object with a large number of polygons, There is a problem that an inappropriate frame image in which some objects are not displayed is generated due to an increase in the burden of image processing. Therefore, in order to solve the problem of display omission, the CPU calculation load is reduced by arbitrarily changing the clipping space for selecting objects in the field of view, and an appropriate image without display omission is generated. The technique which implement | achieved is known (for example, refer patent document 1).
Japanese Patent Laid-Open No. 11-144063

  One of the methods for generating an image based on the viewpoint is a hidden surface removal process using a Z buffer method. In this method, the Z value of each pixel of the image drawn in the frame buffer is stored in the Z buffer, and whether or not writing to the frame buffer (update of color information) is performed according to the Z value stored in the Z buffer. It is determined. The Z buffer stores a depth value based on the viewpoint as a Z value corresponding to each pixel of the frame buffer. Specifically, a Z value is assigned to a range from the viewpoint position to a position determined as, for example, infinity, and the Z value corresponding to the depth value is stored in the Z buffer.

In this case, the accuracy of the Z value is determined by the number of bits of the Z value. Specifically, the greater the number of bits of the Z value, the smaller the depth value (more specifically, the distance from the viewpoint in the game space) with respect to the unit value of the Z value, that is, the accuracy of the Z value increases. For example, when the distance 1 km is represented by 8 bits (256 = 2 ⁸ ), the distance is about 3.9 m with respect to the Z value “1”, but when the distance is 12 bits (4096 = 2 ¹² ), the distance is about 0. 24 m. In the hidden surface removal processing by the Z buffer method, the object context is determined for each pixel based on the Z value. However, if the accuracy of the Z buffer is low, the context may not be determined accurately. For example, when considering objects arranged close to each other, a situation occurs in which the Z values are equal even though the depth values are different from each other, and this causes the object context to be completely or partially. Inconveniences such as drawing in reverse. This problem becomes a problem when an image is generated by zooming the camera using a model object in which one model is composed of many objects as a subject.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to prevent inappropriate image generation due to the fact that the positional relationship before and after an object is not accurately determined by improving the accuracy of the Z value. Yes.

The first invention for solving the above-described problems is
A program for causing a computer to generate an image of a virtual space viewed from a virtual camera based on the Z buffer method (for example, the game program 410 in FIG. 12),
Of all the depths from the virtual camera to the farthest drawing position, setting means for setting a Z value application range for applying the Z value used in the Z buffer method (for example, the replay control unit 211 in FIG. 12; step in FIG. 16) B11-B19),
The virtual space viewed from the virtual camera by assigning a Z value to the set Z value application range, performing hidden surface removal processing in the Z value application range by a Z buffer method based on the assigned Z value Image generation means (for example, the replay control unit 211 and the image generation unit 230 in FIG. 12; step B21 in FIG. 16),
As a program for causing the computer to function.

In addition, the twelfth invention
An image generation device (for example, the home game device 1200 of FIGS. 1 and 12) that generates an image of a virtual space viewed from a virtual camera based on the Z buffer method,
Of all the depths from the virtual camera to the farthest drawing position, setting means (for example, the replay control unit 211 in FIG. 12) for setting a Z value application range for applying a Z value used in the Z buffer method;
The virtual space viewed from the virtual camera by assigning a Z value to the set Z value application range, performing hidden surface removal processing in the Z value application range by a Z buffer method based on the assigned Z value Image generation means (for example, the replay control unit 211 and the image generation unit 230 in FIG. 12) for generating
It is an image generation apparatus provided with.

  According to the first or twelfth invention, the Z value application range for applying the Z value used in the Z buffer method is set out of the entire depth from the virtual camera to the farthest drawing position, and the set Z value application A Z value is assigned to the range, and a hidden surface removal process in the Z value application range is performed by a Z buffer method based on the assigned Z value, thereby generating an image of the virtual space viewed from the virtual camera.

  That is, the Z value is not assigned to the entire depth as in the prior art, but the Z value is assigned to the Z value application range that is a partial range of the entire depth. As a result, the depth value with respect to the unit value of the Z value decreases, that is, the accuracy of the Z value increases, so that the context is accurately determined even between two adjacent objects, and the object context is reversed. Inappropriate images are prevented from being generated.

The second invention is the program of the first invention,
Causing the computer to function as selection means (for example, the replay control unit 211 in FIG. 12) for selecting a subject object from objects in the virtual space;
The setting means is a program for causing the computer to function so as to set a predetermined range including the selected subject object in the entire depth from the virtual camera to the farthest drawing position as the Z value application range. is there.

  According to the second invention, a subject object is selected from objects in the virtual space, and a predetermined range including the selected subject object in the entire depth from the virtual camera to the farthest drawing position is a Z value. Set as the scope of application. Accordingly, a predetermined range including the subject object, that is, a range that can be drawn based on the virtual camera is appropriately set as the Z value application range.

In this case, as a third invention,
The selection means selects a plurality of objects as the subject object,
The setting means sets a Z value application range so as to include all the selected objects;
Thus, a program for causing the computer to function may be used.

  According to the third aspect, a plurality of objects as subject objects of the virtual camera are selected, and the Z value application range is set to include all the selected objects.

As a fourth invention,
The selection means selects a plurality of objects as the subject object,
The setting unit may be a program for causing the computer to function so as to set a Z value application range including each of the selected objects.

  According to the fourth aspect of the present invention, a plurality of objects that are subject objects of the virtual camera are selected, and a Z value application range that includes each of the selected objects is set. Thereby, for example, when a plurality of airplane objects are flying at a distance in the game space, such as flight simulation, a plurality of subject objects are arranged at a certain distance, and between the subject objects When there are no objects to be drawn in the space (area), a plurality of Z value application ranges are set so as to include each of the subject objects, thereby efficiently setting the Z value application range and increasing the accuracy of the Z value. It becomes possible.

The fifth invention is a program according to any one of the second to fourth inventions,
The setting means is a program for causing the computer to function so as to variably set a depth length of the Z value application range according to a distance between the virtual camera and the subject object.

  According to the fifth aspect, the depth length of the Z value application range is variably set according to the distance between the virtual camera and the subject object. When the distance between the virtual camera and the subject object changes, the visual field of the virtual camera changes, that is, the range to be drawn changes. For this reason, by setting the depth length of the Z value application range variably according to the change in the distance between the virtual camera and the subject object, it is possible to efficiently set the Z value application range and increase the accuracy of the Z value. It becomes.

In this case, as in the sixth invention,
The setting unit may be a program for causing the computer to function so that the Z value application range is narrowed as the distance between the virtual camera and the subject object is longer.

  According to the sixth aspect of the invention, the Z value application range is set to be narrower as the distance between the virtual camera and the subject object is longer. By the way, the end position of the Z value application range and the position on the near side as viewed from the virtual camera is set between the virtual camera and the subject object. Depending on the arrangement of objects in the virtual space, the object to be drawn may not be positioned between the virtual camera and the subject object. In such a case, the position on the near side of the Z value application range is determined by the subject object. By setting the close position, the Z value application range can be set to be narrower. For this reason, as the distance between the virtual camera and the subject object is longer, the Z value application range is set to be narrower, so that the Z value application range can be set efficiently and the accuracy of the Z value can be increased. .

A seventh invention is a program according to any one of the first to fourth inventions,
The setting means is a program for causing the computer to function so as to variably set a depth length of the Z value application range according to an angle of view of the virtual camera.

  According to the seventh aspect, the depth length of the Z value application range is variably set according to the angle of view of the virtual camera. When the angle of view of the virtual camera changes, the field of view of the virtual camera changes, that is, the range to be drawn changes. For this reason, by setting the depth length of the Z value application range variably according to the change in the angle of view of the virtual camera, it is possible to efficiently set the Z application range and increase the accuracy of the Z value.

In this case, as an eighth invention,
The setting unit may be a program for causing the computer to function so that the Z value application range is narrowed as the angle of view of the virtual camera is narrowed.

  According to the eighth aspect of the invention, the Z value application range is set to be narrower as the angle of view of the virtual camera is narrower. Narrowing the angle of view of the virtual camera corresponds to zooming, and the drawn range is narrowed. Therefore, by setting the Z value application range to be narrower as the angle of view of the virtual camera is narrower, it is possible to efficiently set the Z value application range and increase the accuracy of the Z value.

A ninth invention is a program according to any one of the first to fourth inventions,
The setting means is a program for causing the computer to function so as to variably set a depth length of the Z value application range according to a depression angle of the virtual camera.

  According to the ninth aspect, the depth length of the Z value application range is variably set according to the depression angle of the virtual camera. When the depression angle of the virtual camera changes, the visual field of the virtual camera changes, that is, the range to be drawn changes. For this reason, by setting the depth length of the Z value application range variably according to the change in the depression angle of the virtual camera, it is possible to efficiently set the Z value application range and increase the accuracy of the Z value.

In this case, as a tenth invention,
The setting unit may be a program for causing the computer to function so that the Z value application range is narrowed as the depression angle of the virtual camera is increased.

  According to the tenth aspect, the Z value application range is set to be narrower as the depression angle of the virtual camera is larger. For example, when a virtual camera is set so that an object placed on a substantially plane is viewed from obliquely above, if the other setting parameters such as position and angle of view are the same, the larger the depression angle, the more the line of sight of the virtual camera The drawing range becomes narrower as the direction approaches the vertical direction. Conversely, the smaller the depression angle, the closer the line-of-sight direction becomes to the horizontal direction and the wider the drawing range. For this reason, by setting the Z value application range to be narrower as the depression angle of the virtual camera is larger, it is possible to efficiently increase the accuracy of the Z value in which the Z value application range is set.

  An eleventh aspect of the invention is a computer-readable information storage medium (for example, the storage unit 400 in FIG. 12) storing the program of any one of the first to tenth aspects of the invention.

  Here, the information storage medium is a storage medium such as a hard disk, an MO, a CD-ROM, a DVD, a memory card, or an IC memory that can be read by a computer. Therefore, according to the eleventh aspect of the invention, the same effect as any of the first to tenth aspects can be obtained by causing the computer to read the information stored in the information storage medium and executing the arithmetic processing. be able to.

  According to the present invention, Z values are not assigned to all depths as in the prior art, but Z values are assigned and assigned to Z value application ranges that are a partial range of all depths. A hidden surface removal process within the Z value application range is performed by the Z buffer based on the Z value, and an image of the virtual space viewed from the virtual camera is generated. As a result, the depth value with respect to the unit value of the Z value decreases, that is, the accuracy of the Z value increases, so that the context is accurately determined even between two adjacent objects, and the object context is reversed. Inappropriate images are prevented from being generated.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following, a case where a motorcycle racing game is executed on a home game device will be described. However, embodiments to which the present invention can be applied are not limited thereto.

[Appearance of home game device]
FIG. 1 is a schematic external view of a consumer game device 1200 according to this embodiment. As shown in the figure, a consumer game device 1200 includes a main body device 1210, a game controller 1220 having direction keys 1221 and button switches 1222 for a player to input a game operation, and a display 1230 having a speaker 1231. Prepare. The game controller 1220 is connected to the main apparatus 1210, and the display 1230 is connected to the main apparatus 1210 by a cable 1201 capable of transmitting image signals and sound signals.

  Game information including programs and data necessary for the main body device 1210 to perform game processing is stored in, for example, a CD-ROM 1212, a memory card 1213, an IC card 1214, or the like, which is an information storage medium detachable from the main body device 1210. Has been. The game information and the like may be acquired from an external device by connecting to the communication line N via the communication device 1215 provided in the main body device 1210. Here, the communication line N means a communication path through which data can be exchanged. That is, the communication line N is meant to include a communication network such as a telephone communication network, a cable network, and the Internet in addition to a dedicated line (dedicated cable) for direct connection and a LAN using Ethernet (registered trademark). The communication method is not limited to wired / wireless.

  The main unit 1210 includes a control unit 1211 equipped with a memory such as a CPU, ROM, and RAM, and an information storage medium reader such as a CD-ROM 1212. The main device 1210 executes various game processes based on the game information read from the CD-ROM 1212 and the like and the operation signal from the game controller 1220, and generates a game screen image signal and a game sound signal. Then, the generated image signal and sound signal are output to the display 1230, a game screen is displayed on the display 1230, and a game sound is output from the speaker 1231. The player enjoys the motorcycle racing game by operating the game controller 1220 while watching the game screen displayed on the display 1230 and listening to the game sound output from the speaker 1231.

[principle]
In the motorcycle racing game of the present embodiment, after the game ends, replay is performed to reproduce the game play based on the replay data. FIG. 2 is a diagram illustrating an example of a game space during replay. The game space at the time of replay is reconstructed by arranging objects such as the motorcycle 20 on the substantially flat race course 10 based on the replay data. The replay data is play data accumulated and recorded during the progress of the game, and includes data on the position and orientation of each object for each frame, or operation data by the player.

  A plurality of replay camera CMs are set in the game space at the time of replay. Each replay camera CM includes a plurality of replay cameras CM, such as by looking down at a part of the race course 10 from diagonally above, unlike in a game in which the vehicle (the motorcycle 20 to be operated by the player who is the player character) is followed obliquely from behind. Set to position. In the figure, five replay cameras CM1 to CM5 are set. Each of the replay cameras CM1 to CM5 is associated with each partial course obtained by dividing the race course 10 into five along the route, and is switched when the vehicle travels through the corresponding partial course.

  The replay camera CM is fixed in position, and is controlled so that the line-of-sight direction is directed toward the host vehicle by variably controlling the camera angle and the angle of view φ. The camera angle includes a pitch angle X that is a vertical swing angle, a yaw angle Y that is a horizontal swing angle, and a roll angle Z that is a rotation angle centered on the viewing direction.

  An image based on any one of the plurality of replay cameras CM (for example, a replay camera CM associated with a partial course in which the vehicle is located in the race course 10) is replayed. Displayed on the replay screen as an image.

  The replay image is generated using hidden surface removal processing by the Z buffer method. The Z buffer method is a method that uses a Z buffer that stores the Z value of a drawn image for each pixel separately from the frame buffer that stores the color of the generated image for each pixel, and is stored in the Z buffer. Whether to write to the frame buffer (update of color information) is determined according to the Z value. In the Z buffer, the depth distance (depth value) of each pixel based on the replay camera CM is stored as a Z value. Specifically, the Z value is applied to the range to be drawn by the replay camera CM, and the Z value assigned corresponding to the depth distance is stored in the Z buffer.

  FIG. 3 is a diagram illustrating application of a conventional Z value. In the figure, the horizontal direction is shown as the depth distance of the replay camera CM. As shown in the figure, conventionally, a range (all depth) from the position P0 of the replay camera CM to a position corresponding to infinity (the farthest drawing position) P1 is the Z value application range, and this Z value application range. Z value is applied to.

Specifically, when the number of bits of the Z value of each pixel stored in the Z buffer is “n”, the Z value at the position P0 of the replay camera CM is set to “0”, and the Z value at the farthest drawing position P1. Is “2 ⁿ −1”. Then, the range from the position P0 that is the Z value application range to the drawing farthest position P1 is equally divided by the maximum number “2 ⁿ ” that can be expressed by the Z value, and a Z value is assigned to each. That is, a depth distance obtained by equally dividing the Z value application range by 2 ⁿ is assigned to the unit value of the Z value.

For example, the depth distance from the position P0 of the replay camera CM to the drawing farthest position P1 is “30 km”, and the number of bits of the Z value is “16”. Then, when the Z value at the position P0 is set to “0”, the Z value at the farthest drawing position P1 is set to “2 ¹⁶ −1”, and the Z value is assigned to the Z value application range from the position P0 to the farthest drawing position P1. , A depth distance “about 46 cm (= 30 km / 2 ¹⁶ )” is assigned to the minimum unit “1” of the Z value. That is, the accuracy of the Z value is “about 46 cm”.

  On the other hand, in this embodiment, the Z value application range is set as shown in FIG. That is, the Z value application range is a partial range from the position P0 of the replay camera CM to the farthest drawing position P1 (full depth) and includes the position Pp of the host vehicle PC that is the target object of the replay camera CM. Set as Of the both end positions of the Z value application range, a position nearer to the replay camera CM (front side position) P2 is set between the position P0 of the replay camera CM and the position Pp of the own vehicle, and a position on the far side ( The back side position P3 is set between the position Pp of the host vehicle and the drawing farthest position P1.

The Z value is applied to this Z value application range. For example, when the Z value is n bits, the Z value at the near side position P2 is set to “0”, and the Z value at the back side position P3 is set to “2 ⁿ −1”. Then, the Z value application range from the near side position P2 to the back side position P3 is equally divided by “2 ⁿ ”, and a Z value is assigned to each.

  Further, the Z value application range may be set in any way, but in the following, as shown in FIG. 5B, the back side position P3 is made to coincide with the drawing farthest position P1 of the replay camera CM, and the front side The Z value application range is set by determining the position P2 according to the replay camera CM.

The near side position P2 of the Z value application range is set as shown in FIG. That is, according to Expression (1), the distance L2 is calculated by multiplying the distance Lp from the replay camera position P0 to the own vehicle position Pp by the coefficient k determined based on the replay camera CM. Then, a position away from the position P0 of the replay camera by the distance L2 is set as the near side position P2.
L2 = Lp × k (1)
However, 0 <k <1.

  By the way, in the motorcycle racing game, as shown in FIG. 6, the replay camera CM is set so that the race course 10 is looked down from the upper outside. However, in this case, since the motorcycle 20 to be drawn is arranged on the race course 10, an object to be drawn is not located in a partial area on the near side in the field of view of the replay camera CM. For this reason, for example, when it is set so that the line-of-sight direction is directed to the own vehicle PC, the near side position P2 of the Z value application range is set between the replay camera CM and the own vehicle PC, and the road surface, background, etc. The farthest drawing position P1 set as the rear position is set as the back position P3 of the Z value application range.

  Further, as shown in FIG. 7, the drawing range of the replay camera CM differs depending on the distance between the replay camera CM and the own vehicle. In the figure, a replay camera CM1 whose distance from the own vehicle is Lp1 and a replay camera CM2 whose distance from the own vehicle is Lp2 are arranged. However, Lp1 <Lp2. Further, the replay cameras CM1 and CM2 are set such that the angle of view φ and the camera angle are equal, only the positions are different, and the line-of-sight direction is toward the host vehicle PC.

  The replay camera CM2 is larger than the replay camera CM1 in the field of view of each of the replay cameras CM1 and CM2 and the area where the object to be drawn is not located. For this reason, the near side position P2 of the Z value application range can be set to a position far from the replay camera CM as the distance Lp to the own vehicle is longer (far). In the figure, the distance from the replay camera CM2 to the near side position P2 is longer than the distance from the replay camera CM1 to the near side position P2. Therefore, as shown in Expression (1), the distance L2 to the near side position P2 is determined so as to be proportional to the distance Lp to the host vehicle.

The coefficient k for determining the near side position P2 of the Z value application range is determined according to the replay camera CM. Specifically, it is determined according to the angle of view φ and the depression angle θ of the replay camera CM, and is determined based on the coefficient k _φ determined based on the angle of view φ and the depression angle θ as shown in the following equation (2). It is calculated by multiplying a coefficient k _theta being.
k = k _φ × k _θ (2)

FIG. 8 is a diagram for explaining the determination of the coefficient k _φ according to the angle of view φ of the replay camera.
FIG. 4A shows the case of the replay camera CM1 having the angle of view φ1, and FIG. 4B shows the case of the replay camera CM2 having the angle of view φ2. However, φ1> φ2. Further, the replay cameras CM1 and CM2 are set such that the parameters (position and camera angle) other than the angle of view φ are equal and the line-of-sight direction is directed toward the own vehicle. That is, the replay camera CM2 corresponds to the zoom of the replay camera CM1.

  According to the figure, although both the replay cameras CM1 and CM2 have a predetermined range centered on the own vehicle as the drawing range, the ranges are different. That is, the replay camera CM1 has a smaller drawing range than the replay camera CM2, and for example, the other vehicle EC that is in the drawing range in the replay camera CM1 does not enter the drawing range in the replay camera CM2.

That is, when the angle of view φ of the replay camera CM is different, the drawing range of the replay camera CM is different. Specifically, the drawing range becomes narrower as the angle of view φ is narrower. For this reason, as the angle of view φ of the replay camera CM is narrowed, the near side position P2 of the Z value application range can be set to a position farther from the replay camera CM. That is, the smaller the angle of view φ, the larger the coefficient k _φ is set.

FIG. 9 is a graph showing an example of the relationship between the angle of view φ and the coefficient k _φ . In the figure, the horizontal axis represents the angle of view φ of the replay camera CM, and the vertical axis represents the coefficient k _φ . If the figure, the coefficient k _phi, substantially smaller in proportion to the angle phi as angle phi increases. The shape of the graph representing the relationship between the angle of view φ and the coefficient k _φ is not limited to this, and other shapes may be used as long as the coefficient k _φ decreases as the angle of view φ increases.

FIG. 10 is a diagram for explaining the determination of the coefficient k _θ according to the depression angle θ of the replay camera CM. In the figure, a replay camera CM1 having a depression angle θ1 and a replay camera CM2 having a depression angle θ2 are arranged. However, θ1> θ2. Further, both the replay cameras CM1 and CM2 are set such that the angle of view φ and the distance Lp between the vehicle PC and the vehicle PC are equal and the line-of-sight direction is directed toward the vehicle PC.

  According to the figure, although both the replay cameras CM1 and CM2 have a predetermined range centered on the own vehicle as the drawing range, the ranges are different. That is, the replay camera CM1 has a smaller drawing range than the replay camera CM2, and for example, the other vehicle EC that is in the drawing range in the replay camera CM2 does not enter the drawing range in the replay camera CM1.

  That is, when the depression angle θ of the replay camera is different, the drawing range of the replay camera CM is different. Specifically, the drawing range becomes narrower as the depression angle θ is larger. For this reason, as the depression angle θ of the replay camera CM is larger, the near side position P2 of the Z value application range can be set to the back side position as viewed from the replay camera CM. That is, the coefficient k is set larger as the depression angle θ is larger.

Figure 11 is a graph showing an example of the relationship between the depression angle theta and the coefficient k _theta. In the figure, the horizontal axis represents the depression angle theta replay camera CM, indicates the coefficient k _theta on the vertical axis. If the figure, the coefficient k _theta, as the depression angle theta increases, increases approximately in proportion to the depression angle theta. The graph representing the relationship between the depression angle θ and the coefficient k _θ is not limited to this, and any other graph may be used as long as the coefficient k _θ increases as the depression angle θ increases.

[Function configuration]
FIG. 12 is a block diagram showing a functional configuration of the consumer game device 1200 in the present embodiment. As shown in the figure, the consumer game device 1200 functionally includes an operation input unit 100, a processing unit 200, an image display unit 330, a sound output unit 340, and a storage unit 400. Is done.

  The operation input unit 100 receives an operation instruction input from the player and outputs an operation signal corresponding to the operation to the processing unit 200. This function is realized by, for example, a button switch, lever, dial, mouse, keyboard, various sensors, and the like. In FIG. 1, the game controller 1220 corresponds to this.

  The processing unit 200 performs various operations such as overall control of the home game device 1200, game progress, and image generation. This function is realized by, for example, an arithmetic device such as a CPU (CISC type, RISC type), ASIC (gate array, etc.) or a control program thereof. In FIG. 1, a CPU or the like mounted on the control unit 1211 corresponds to this.

  The processing unit 200 is mainly based on a game calculation unit 210 that performs calculation processing related to the execution of the game, and various data obtained by the processing of the game calculation unit 210 from a given viewpoint such as a virtual camera. The image generation unit 230 generates an image in the virtual three-dimensional space (game space), and the sound generation unit 240 generates a game sound such as a sound effect or BGM.

  The game calculation unit 210 executes various game processes based on operation signals input from the operation input unit 100, programs and data read from the storage unit 400, and the like. As the game process, for example, a process for setting a game space by arranging objects such as a race course 10, a motorcycle 20, and a background in a virtual space, and a control of a player character (own vehicle) based on an operation signal from the operation input unit 100 There are hit intersection determination (hit check) of an object, control of a viewpoint (virtual camera), and the like. In the present embodiment, the game calculation unit 210 includes a replay control unit 211.

  The replay control unit 211 controls the progress of the replay based on the replay data 432 after the game ends. Specifically, first, based on the replay data 432, the game space is reconstructed by arranging objects such as the race course 10, the motorcycle 20, and the background in the virtual space. Next, with reference to the replay camera data 433, a plurality of replay cameras CM are arranged in the reconstructed game space.

  Here, the replay data 432 is a data group such as the position and posture of each object such as the motorcycle 20 for each frame, which is accumulated and stored during the game. Note that the replay data 432 may be operation data input by the player for each frame, instead of data such as the position and orientation of the object.

  The replay camera data 433 is data related to the replay camera CM arranged in the game space. FIG. 13 shows an example of the data configuration of the replay camera data 433. According to the figure, the replay camera data 433 is prepared for each replay camera CM, and stores the corresponding replay camera 433a, the drawing farthest position 433b, setting data 433c, and control data 433g.

  The replay camera 433a stores identification data of the corresponding replay camera CM. The drawing farthest position 433b stores a distance L1 from the corresponding replay camera CM to a position (drawing farthest position P1) predetermined as an infinite position. This distance L1 is a fixed value.

  The setting data 433c stores an initial value 433e and a current value 433f in association with each parameter 433d of the replay camera CM. The parameters 433d include a position (x, y, z) in the game space, a pitch angle X, a yaw angle Y, a roll angle Z, which are camera angles, and a field angle φ. The pitch angle X is the depression angle θ.

  The control data 433g stores control contents 433i in association with each parameter 433h. The control content 433i stores data specifying whether the corresponding parameter is “fixed” or “variable”.

  The replay control unit 211 refers to the setting data 433c of the corresponding replay camera data 433 for each replay camera CM, and sets each parameter to a predetermined initial value, thereby reconstructing the replay camera CM. (Initial setting).

  Thereafter, the replay control unit 211 starts replay. During replay, the following processing is repeated for each frame. That is, (1) Based on the replay data 432, movement control (rearrangement) of objects such as the motorcycle 20 is performed. Next, (2) one replay camera CM that generates an image is selected from a plurality of set replay cameras CM based on the position of the vehicle, for example. Then, (3) the replay camera CM is controlled according to the control data 433g of the replay camera data 433 corresponding to the selected replay camera CM. In other words, the replay camera is controlled (rearranged) so that the line-of-sight direction is directed toward the host vehicle PC by changing a parameter whose control content is set to “variable” in the control data 433g.

Subsequently, (4) referring to the replay camera data 433 corresponding to the selected replay camera CM, the farthest drawing position P1 of the replay camera CM is determined, and the determined farthest drawing position P1 is determined as the Z value application range. The back side position P3. Further, the near side position P2 of the Z value application range is determined. That is, referring to the setting data 433c of the corresponding replay camera data 433, based on the angle phi of the replay camera CM, it calculates the coefficient k _phi in accordance with the coefficient calculation data 435. Also, the coefficient k _θ is calculated according to the coefficient calculation data 435 based on the depression angle θ (pitch angle X) of the replay camera CM. Then, to calculate the coefficient k is multiplied by the coefficient k _phi and the coefficient k _theta calculated. Further, a distance Lp from the replay camera CM to the host vehicle is calculated, and a distance L2 to the near side position P2 of the Z value application range is calculated by multiplying the distance Lp by the calculated coefficient k.

Here, the coefficient calculation data 435 is data defining a calculation method of the coefficient k for determining the near side position P2 of the Z value application range. In this embodiment, it calculates a relational expression between the angle phi and the coefficient k _phi for example exemplified in FIG. 9 for calculating the coefficient k _phi based on the angle phi, the coefficient k _theta based on the depression angle theta and and a relationship between the coefficient k _theta depression theta for example exemplified in FIG. 11 for the coefficient k _phi, and a formula (2) is a calculation formula for calculating the coefficient k from k _theta .

  The Z value application range determined by the replay control unit 211 is stored in the Z value application range data 434. FIG. 14 shows an example of the data configuration of the Z value application range data 434. The Z value application range data 434 stores the near side position 434a and the back side position 434b of the Z value application range. Each position stores a distance L from the corresponding replay camera CM.

  Then, the replay control unit 211 sets the range from the calculated near side position P2 to the back side position P3 as the Z value application range, and performs a hidden surface removal process within the Z value application range by the Z buffer method on the image generation unit 230. By doing so, an image based on the replay camera CM is generated, and the generated image is displayed on the image display unit 330.

  The sound generation unit 240 generates game sounds such as sound effects and BGM used during the game, and outputs a sound signal of the generated game sound to the sound output unit 340. The sound output unit 340 outputs game sounds such as BGM and sound effects based on the sound signal from the sound generation unit 240. This function is realized by, for example, a speaker. In FIG. 1, the speaker 1231 corresponds to this.

  The storage unit 400 stores a system program for realizing various functions for causing the processing unit 200 to control the home game device 1200 in an integrated manner, a program and data necessary for executing the game, and the like. Used as a work area of the processing unit 200, temporarily stores calculation results executed by the processing unit 200 according to various programs, input data input from the operation input unit 100, and the like. This function is realized by, for example, various IC memories, hard disks, CD-ROMs, DVDs, MOs, RAMs, VRAMs, and the like. In FIG. 1, ROM, RAM, and the like mounted on the control unit 1211 correspond to this.

  The storage unit 400 stores a game program 410 and game data for causing the processing unit 200 to function as the game calculation unit 210, and a frame buffer 421 and a Z buffer 422 are formed. The game program 410 includes a replay program 411 for causing the game program 410 to function as the replay control unit 211. The game data includes object data 431, replay data 432, replay camera data 433, Z value application range data 434, and coefficient calculation data 435.

  The object data 431 is data about each object arranged in the game space. The data such as the race course 10 and the background, the current position and posture of each motorcycle 20 as a character, the data on the moving speed, the motorcycle 20 It includes modeling data, texture data, etc., which are data of each object that constitutes.

[Process flow]
FIG. 15 is a flowchart for explaining the flow of the game process in the present embodiment. This process is realized by the game calculation unit 210 executing the game program 410.

  According to the figure, the game calculation unit 210 first arranges the race course 10, the background, the motorcycle 20 of the host vehicle and the other vehicle, and the viewpoint (virtual camera) in the virtual space to perform the initial setting of the game space (step A1). Thereafter, the game process is executed to start the game (step A3). During the game, the following processing is performed for each frame. That is, (1) a process of controlling the own vehicle according to operation data input from the operation input unit 100, (2) a process of automatically controlling another vehicle according to a predetermined control routine, and (3) each motorcycle of the own vehicle and the other vehicle A process of accumulating and adding data such as 20 positions and postures to the replay data 432 as play data in the frame is performed.

  When the game ends, the game calculation unit 210 determines whether to replay the ended game. The determination as to whether or not to perform replay is made based on, for example, whether or not a replay start instruction from the player has been input from the operation input unit 100. If replay is performed (step A5: YES), the replay control unit 211 executes replay processing (step A7).

  FIG. 16 is a flowchart for explaining the flow of the replay process. According to the figure, the replay control unit 211 reconstructs the game space by placing objects such as the own vehicle and other vehicles at the initial position in the virtual space based on the replay data 432 (step B1). Further, with reference to the replay camera data 433, a plurality of replay camera CMs are arranged (initially set) in the reconstructed game space (step B3).

  Thereafter, the process of Loop A is executed for each frame until the replay is completed. In the loop A, the replay control unit 211 controls movement of each object such as the own vehicle and other vehicles by one frame based on the replay data 432 (step B5). Next, one replay camera CM that performs image generation is selected from a plurality of set replay camera CMs based on the position of the vehicle, for example (step B7). Then, the selected replay camera CM is controlled so that the line-of-sight direction faces the host vehicle according to the control data 433g of the corresponding replay camera data 433 (step B9).

Subsequently, the replay control unit 211 refers to the corresponding replay camera data 433, and sets the farthest drawing position set in the selected replay camera CM as the back position P3 of the Z value application range (step B11). . Further, the coefficient k _φ is calculated with reference to the coefficient calculation data 435 based on the angle of view φ of the selected replay camera CM, and the coefficient k _θ is calculated with reference to the coefficient calculation data 435 based on the depression angle θ. (Step B13). Then calculated coefficient k is multiplied by a coefficient k _theta coefficient k _phi calculated (step B15). Further, a distance Lp from the position of the selected replay camera CM to the position Pp of the own vehicle is calculated (step B17). Then, the calculated distance Lp is multiplied by the calculated coefficient k to calculate the distance L2 to the near side position P2 of the Z value application range (step B19).

  Then, the image generation unit 230 performs image generation based on the selected replay camera CM by performing hidden surface removal processing within the set Z value application range, and causes the image display unit 330 to display the generated image ( Step B21).

  When the replay based on the replay data 432 is finished, the loop A is finished, and then the replay process is finished. When the replay process ends, the game calculation unit 210 ends the game process.

[Hardware configuration]
FIG. 17 is a diagram illustrating an example of a hardware configuration of the consumer game device 1200 according to the present embodiment. According to the figure, the consumer game device 1200 includes a CPU 1000, a ROM 1002, a RAM 1004, an information storage medium 1006, an image generation IC 1008, a sound generation IC 1010, and I / O ports 1012 and 1014. System buses 1016 are connected to each other so as to be able to input and output data. Further, a display device 1018 is connected to the image generation IC 1008, a speaker 1020 is connected to the sound generation IC 1010, a control device 1022 is connected to the I / O port 1012, and a communication device 1215 is connected to the I / O port 1014. It is connected.

  The CPU 1000 executes the entire apparatus in accordance with programs and data stored in the information storage medium 1006, system programs (such as initialization information of the apparatus main body) and data stored in the ROM 1002, input signals input by the control device 1022, and the like. Control and various data processing. The CPU 1000 corresponds to the CPU mounted on the control unit 1211 in FIG. 1 and the processing unit 200 in FIG.

  The ROM 1002, the RAM 1004, and the information storage medium 1006 correspond to the storage unit 400 in FIG. The ROM 1002 stores, in particular, a preset program and data among the system program of the home game device 1200 and the information stored in the storage unit 400 of FIG. The RAM 1004 is used as a work area of the CPU 1000 and stores, for example, given contents of the ROM 1002 and the information storage medium 1006, image data for one frame, calculation results by the CPU 1000, and the like. The information storage medium 1006 is realized by an IC memory card, a hard disk unit that can be attached to and detached from the main unit, an MO, and the like.

  The image generation IC 1008 is an integrated circuit that generates pixel information of a game screen to be displayed on the display device 1018 based on image information from the CPU 1000. The display device 1018 displays a game screen based on the pixel information generated by the image generation IC 1008. The image generation IC 1008 corresponds to the image generation unit 230 in FIG. 12, and the display device 1018 corresponds to the image display unit 330 in FIG. 12 and the display 1230 in FIG.

  The sound generation IC 1010 is an integrated circuit that generates game sounds such as sound effects and BGM based on information stored in the information storage medium 1006 and the ROM 1002, and the generated game sounds are output by the speaker 1020. The sound generation IC 1010 corresponds to the sound generation unit 240 in FIG. 12, and the speaker 1231 corresponds to the sound output unit 340 in FIG. 12 and the speaker 1231 in FIG.

  Note that the processing performed by the image generation IC 1008, the sound generation IC 1010, and the like may be executed in software by the CPU 1000 or a general-purpose DSP.

  The control device 1022 is a device for the player to input various game operations as the game progresses. The control device 1022 corresponds to the operation input unit 100 in FIG. 12 and the game controller 1220 in FIG.

  The communication device 1215 is a device for exchanging various types of information used inside the home game device 1200 with the outside. The communication device 1215 is connected to other game devices to transmit / receive given information according to the game program, It is used for transmitting and receiving information such as game programs via a communication line. The communication device 1215 corresponds to a communication device provided in the main body device 1210 of FIG.

[Screen example]
FIG. 18 is a screen example to which the present embodiment is applied, and is an image generated by using the motorcycle OB as a target object based on the same replay camera CM in the same game space. FIG. 4A shows an example of an image by a conventional method. That is, as described with reference to FIG. 3A, the image example is obtained when the Z value is applied with the Z value application range from the position P0 of the replay camera CM to the farthest drawing position P1. FIG. 18B is an image example obtained by the method of the present embodiment. That is, as described with reference to FIG. 4B, a partial range including the position Pp of the motorcycle OB, which is the target object, from the position P0 of the replay camera CM to the farthest drawing position P1, and the position P0. This is an image example when the Z value is applied with the range from the near side position P2 set between the position Pp and the far side position P3 coinciding with the farthest drawing position P1 as the Z value application range.

  The motorcycle OB is a model object composed of a plurality of objects. For example, the front wheel OB1 and the front fork OB2 in front of the vehicle body are configured to be covered with a cowl OB3 from the front outside. However, in FIG. 18A, the front wheel OB1, the front fork OB2, and the cowl OB3 with respect to the replay camera CM are determined to be reversed, and the front wheel OB1 and the front wheel that should be behind the cowl OB3 are determined. The fork OB2 is drawn so as to be in front of the cowl OB3. This is because the depth value with respect to the unit value of the Z value is large, and the same value is assigned as the Z value of each of the front wheel OB1, the front fork OB2, and the cowl OB3. On the other hand, in the same figure (b) using the method of this embodiment, the front-rear relation is correctly determined, and the cowl OB3 is drawn in front of the front wheels OB1 and the front fork OB2. This is because an appropriate Z value corresponding to the depth distance is assigned to each object constituting the motorcycle OB.

  FIG. 19 is another screen example to which the present embodiment is applied, and is an image in which the motorcycle OB on the right side of the image is generated as a subject object based on the same replay camera CM in the same game space. FIG. 4A is an example of an image by a conventional method, and FIG. 4B is an example of an image by the method of the present embodiment.

  As shown in FIG. 18 (a) using the conventional method, the front wheel OB1, front fork OB2, and cowl OB3 of the motorcycle OB are based on the replay camera CM as in FIG. 18 (a). The front wheel OB1 and the front fork OB2 that should be behind the cowl OB3 are drawn so as to be in front of the cowl OB3. On the other hand, in FIG. 19B using the method of the present embodiment, the front-rear relationship is correctly determined as in FIG. 18B described above, and the front wheels OB1 and front forks OB2 of the motorcycle OB are in front of the hands. Are drawn so that there is a cowl OB3.

[Action / Effect]
According to the present embodiment, at the time of replay, the Z value application range including the position Pp of the subject vehicle PC that is the subject object is set within the range from the position P0 of the replay camera CM to the farthest drawing position P1. Of the both end positions of the Z value application range, the far side position P3 far from the replay camera CM is set as the drawing farthest position P1, and the near side position P2 near is set based on the replay camera CM. That is, the coefficient k _phi defined based on the angle phi replay camera CM, coefficient k is calculated by multiplying the coefficient k _theta defined based on the depression angle theta, the position P0 of the replay camera CM of the vehicle The distance L2 to the near side position P2 is calculated by multiplying the distance Lp to the position Pp by the calculated coefficient k. Then, the Z value is applied to the set Z value application range, and a replay image is generated by performing hidden surface removal processing within the Z value application range based on the replay camera CM.

  As a result, the depth value with respect to the unit value of the Z value decreases, that is, the accuracy of the Z value increases, so that the context is accurately determined even between two adjacent objects, and the object context is reversed. Inappropriate images are prevented from being generated. Also, it is effective to set the near side position P2 of the Z value application range based on the distance Lp between the replay camera CM and the subject vehicle PC, the field angle φ and the depression angle θ of the replay camera CM. The Z value application range can be set to

[Modification]
It should be noted that embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can of course be changed as appropriate without departing from the spirit of the present invention.

(A) Z value application range For example, in the above-described embodiment, the back side position P3 of the Z value application range is fixed to coincide with the farthest drawing position P1, and the near side position P2 is varied according to the replay camera CM. However, the back side position P3 may be variable according to the position of the host vehicle, for example. Furthermore, both the near side position P2 and the far side position P3 of the Z value application range may be made variable.

(B) Coefficient k
In the above-described embodiment, the coefficient k for determining the near side position P2 of the Z value application range is determined by the coefficient k _φ determined based on the angle of view φ of the replay camera CM and the coefficient k determined based on the depression angle θ. _Although it is determined by multiplying by _θ , it may be determined by only one of the coefficients k _φ and k _θ .

  Further, the coefficient k may be a fixed value determined in advance for each replay camera CM regardless of parameters such as the angle of view φ and the depression angle θ. In this case, since the drawing range of the replay camera CM is roughly determined from the setting contents such as the position and the camera angle, the coefficient k may be set according to the setting contents.

(C) Subject Object In the above-described embodiment, the player character's own vehicle is set as the subject object, and the Z value application range is set so as to include the position Pp of the own vehicle. The Z value application range may be set with an object, for example, another vehicle as a subject object.

  In addition, the Z value application range is set so that a plurality of objects including not only the own vehicle but also other vehicles (for example, a predetermined other vehicle designated before the start of the race) are subject objects, and the positions of the plurality of subject objects are included. You may decide to do it.

  Specifically, as shown in FIG. 20, the Z value application range is set so as to include the positions of all of the plurality of subject objects. In the figure, the Z value application range is set so as to include the positions Pp1 and Pp2 of the two subject objects of the host vehicle PC and the other vehicle EC. In this case, the distance L2 from the replay camera CM to the front position P2 of the Z value application range is obtained by multiplying the distance Lp from the replay camera CM to the position Pp1 of the host vehicle PC that is the subject object closest to the replay camera CM. decide.

Further, as shown in FIG. 21, a plurality of Z value application ranges may be set so as to include the positions of the plurality of subject objects. In this figure, the host vehicle PC and the other vehicle EC are subject objects, and a Z value application range A including the position Pp1 of the host vehicle PC and a Z value application range B including the position Pp2 of the other vehicle EC are set. Yes. And Z value is applied to each Z value application range. That is, the Z value of the near side position P2a of the Z value application range A close to the replay camera CM is set to “0” and the Z value of the back side position P3a is set to “2 ^m −1”. The Z value application range up to P3a is equally divided by “2 ^m ”, and a Z value “0 to 2 ^m −1” is assigned. Further, the Z value of the near side position P2b of the Z value application range B far from the replay camera CM is set to “2 ^m ”, the Z value of the back side position P3b is set to “2 ⁿ −1”, and the back side from this near side position P2b. The Z value application range up to the position P3b is equally divided by “2 ^(nm) ”, and Z values “2 ^m to 2 ⁿ −1” are assigned. However, m <n.

(D) At the time of application In the above-described embodiment, the present invention is applied at the time of replay. However, it is needless to say that the present invention can also be applied at the time of a game.

(E) Applicable Game Device In the above-described embodiment, the case where the present invention is applied to a home game device has been described. However, the game device is not limited to the home game device 1200 shown in FIG. The present invention can be similarly applied to various devices such as a portable game device and a large attraction device in which a large number of players participate.

  For example, FIG. 22 is an external view showing an example in which the present invention is applied to an arcade game machine. According to the figure, the arcade game device 1300 is formed with the shape of a racing bike as a motif, a housing 1310 that imitates the shape of a racing bike, a display 1320 that displays a game screen, A speaker 1330 for outputting game sound effects and BGM, and a control unit 1340 for executing a motorcycle game by comprehensively controlling the arcade game apparatus 1300 through arithmetic processing.

  The control unit 1340 includes an arithmetic processing unit such as a CPU and a ROM that stores programs and data necessary for controlling the arcade game device 1300 and executing the game. The CPU executes various processes such as a game process by appropriately reading and calculating a program and data stored in the ROM.

  The player spans the housing 1310, looks at the game screen displayed on the display 1320, listens to the game sound output from the speaker 1330, operates the handle 1311 of the housing 1310, determines the left-right direction, and Enjoy a motorcycle racing game by performing the same operations as a real motorcycle, such as inputting acceleration / deceleration with the accelerator grip or brake lever shown.

(F) Game to be applied In the above-described embodiment, the case where the present invention is applied to a motorcycle racing game has been described. However, it is needless to say that the present invention can be similarly applied to other games such as a car racing game and a flight simulation.

An appearance example of a home game device. An example of a game space during replay. Application example of conventional Z value. Application example of Z value of this embodiment. Explanatory drawing of the setting method of near side position P2 of Z value application range. A typical setting example of a replay camera. Explanatory drawing that a drawing range changes with distance with a to-be-photographed object. Explanatory drawing that a drawing range changes with view angles (phi). An example of the relationship between the angle of view φ of the replay camera and the coefficient k _φ . Explanatory drawing that a drawing range changes with depression angles (theta). An example of the relationship between the depression angle θ of the replay camera and the coefficient k _θ . The functional block diagram of a household game device. The data structural example of replay camera data. The data structural example of Z value application range data. Flow chart of game processing. The flowchart of the replay process performed during a game process. The hardware structural example of a household game device. The example of a screen by the method of the past and this embodiment. The example of a screen by the method of the past and this embodiment. The modification of Z value application range. The modification of Z value application range. An example of the appearance of an arcade game device.

Explanation of symbols

1200 Home Game Device 100 Operation Input Unit 200 Processing Unit 210 Game Calculation Unit 211 Replay Control Unit 230 Image Generation Unit 240 Sound Generation Unit 330 Image Display Unit 340 Sound Output Unit 400 Storage Unit 410 Game Program 411 Replay Control Program 421 Frame Buffer 422 Z buffer 431 Object data 432 Replay data 433 Replay camera data 434 Z value application range data 435 Coefficient calculation data

Claims (12)

A program for causing a computer to generate an image of a virtual space viewed from a virtual camera based on the Z buffer method,
Setting means for setting a Z value application range for applying a Z value used in the Z buffer method among all the depths from the virtual camera to the farthest drawing position;
The virtual space viewed from the virtual camera by assigning a Z value to the set Z value application range, performing hidden surface removal processing in the Z value application range by a Z buffer method based on the assigned Z value Image generating means for generating an image of
A program for causing the computer to function as Causing the computer to function as selection means for selecting a subject object from among the objects in the virtual space;
The said setting means is for making the said computer function so that the predetermined range containing the selected to-be-photographed object among all the depths from the said virtual camera to a drawing farthest position may be set as a Z value application range. The program according to 1. The selection means selects a plurality of objects as the subject object,
The setting means sets a Z value application range so as to include all the selected objects;
The program according to claim 2 for causing the computer to function. The selection means selects a plurality of objects as the subject object,
The program according to claim 2, wherein the setting unit causes the computer to function so as to set a Z value application range including each of the selected objects.   The said setting means as described in any one of Claims 2-4 for making the said computer function so that the depth length of the said Z value application range may be variably set according to the distance between the said virtual camera and the said to-be-photographed object. The program described in the section.   The program according to claim 5, wherein the setting unit causes the computer to function so as to set the Z value application range to be narrower as the distance between the virtual camera and the subject object is longer.   The said setting means as described in any one of Claims 1-4 for making the said computer function so that the depth length of the said Z value application range may be variably set according to the angle of view of the said virtual camera. program.   The program according to claim 7, wherein the setting unit causes the computer to function so that the Z value application range is narrowed as the angle of view of the virtual camera is narrowed.   The program according to any one of claims 1 to 4, wherein the setting unit causes the computer to function so as to variably set a depth length of the Z value application range according to a depression angle of the virtual camera. .   The program according to claim 9, wherein the setting unit causes the computer to function so that the Z value application range becomes narrower as the depression angle of the virtual camera is larger.   The computer-readable information storage medium which memorize | stored the program as described in any one of Claims 1-10. An image generation device that generates an image of a virtual space viewed from a virtual camera based on a Z buffer method,
Of all the depth from the virtual camera to the farthest drawing position, setting means for setting a Z value application range for applying a Z value used in the Z buffer method;
The virtual space viewed from the virtual camera by assigning a Z value to the set Z value application range, performing hidden surface removal processing in the Z value application range by a Z buffer method based on the assigned Z value Image generation means for generating the image of
An image generation apparatus comprising: