JP4579964B2 - Image generating apparatus, image generating method, and program - Google Patents

Description

  The present invention relates to an image generation apparatus, an image generation method, and a program suitable for easily generating an image obtained by deforming an object in a virtual space.

  Traditionally, when representing characters such as people and animals in computer graphics, the skeleton is abstracted with line-shaped objects called bones (also called skeletons), and the positions of the bones around each bone are fixed. There has been proposed a technique for obtaining a surface shape called a skin obtained by abstracting the shape of the skin depending on the positions of the points to be formed.

  Here, bones and skins are concepts used in 3D graphics modeling techniques. A bone is a link (line-segmented object) whose position and orientation are determined, and has a rotation axis and a rotation angle that can be rotated at a portion such as a joint of a limb. As described above, the line-shaped object in which the rotational movement is limited is also referred to as “link”.

  In addition, cross-sectional views (ribs) of surface shapes arranged in a three-dimensional space are arranged, and these are connected to form a complicated curved surface. This surface shape is called a skin.

  Generally, since the rib is fixed to the bone, when the bone changes its position and posture, the rib position and posture are also changed. Therefore, vertices that determine the shape of the rib (when the rib is polygonal) and various control points (when the rib is curved) are also fixed to the bone.

  In the modeling technique using bones and skins, various ideas have been made to express the model more naturally. For example, Patent Document 1 discloses an apparatus that can change the shape of a skin near the connection point of two bones to be connected as naturally as possible. According to this, when an elbow or knee in a human or animal skeleton is twisted, the skin near the elbow or knee is not unnaturally thinned.

Further, for example, Patent Document 2 discloses a technique that can display a character at high speed by associating a plurality of bones with a vertex of a polygon and giving the vertex of the polygon a specific gravity value corresponding to the degree of association with the associated bone. It is disclosed.
JP 2007-148856 A JP 2002-92644 A

  In order to deform the skin that is the outer shape of the object, the position and posture of the bone are changed, and the position of the control point fixed to the bone is changed in accordance with the change of the bone position and posture. However, if you want to change the shape of the skin partially, if you try to apply the conventional technology as it is, you must change the position and posture of the entire bone associated with the control points that make up the skin you want to change, There was a problem that even the part of the skin that was not desired to be deformed was deformed.

  In addition, in so-called clay animation using real clay, there is a method to express a character comically by transforming a character partially or entirely into a mess, but trying to express this in virtual space using conventional technology Then, it is necessary to divide the bones into small pieces and connect them or reduce them, and it is necessary to change the basic skeleton of the object to be deformed. On the other hand, clay animation may be deformed or not deformed, and when it is not deformed, there is also a demand for reducing the design burden of the designer as a configuration similar to a conventional three-dimensional (3D) animation. In addition, since it is a fact that the joint portion that connects the bones is desired to be placed only where it is supposed to bend, there is also a demand for not changing the basic skeleton of the object. Therefore, there is a demand for a technique that can easily change the shape of an object while reducing the burden on the designer.

  The present invention solves such a problem, and an object thereof is to provide an image generation apparatus, an image generation method, and a program suitable for easily generating an image obtained by deforming an object in a virtual space. And

  In order to achieve the above object, the following invention is disclosed in accordance with the principle of the present invention.

An image generation apparatus according to a first aspect of the present invention includes a storage unit, a calculation unit, an image generation unit, and an update unit.
The storage unit includes a position of a main bone in a coordinate system (hereinafter referred to as “parent coordinate system”) arranged in the virtual space, and a subordinate in a coordinate system (hereinafter referred to as “main coordinate system”) fixed to the main bone. The position of the bone and the position of the control point associated with the sub bone in the coordinate system (hereinafter referred to as “sub coordinate system”) fixed to the sub bone are stored.
The calculation unit calculates the parent coordinates of the control point based on the position of the main bone in the parent coordinate system, the position of the sub bone in the main coordinate system, and the position of the control point in the sub coordinate system. Calculate the position in the system.
The image generation unit determines the shape of the skin based on the calculated position of the control point, and generates an image representing the shape of the skin arranged in the virtual space.
The update unit updates the position of the sub-bone in the main coordinate system to change the shape of the skin.

Here, the image of the character object arranged in the virtual space is expressed using a main bone, a sub bone, a control point, and a skin.
A bone is a line-shaped object that serves as a skeleton of a character object, and the basic position and orientation of the character object change as the position and orientation of the bone change. In the present invention, two types of bones, a main bone and a sub bone, are defined. The main bone is the skeleton of the character object, and the correspondence between the main bones when the main bones are joined and the shape of the main bone are unchanged, but the main coordinate system of the main bone (the coordinate system fixed in the virtual space) The position at) is variable.
Sub-bones are arranged in the main bone with a predetermined position on the main bone as an initial position. The correspondence between the main bone and the sub bone and the shape of the sub bone are unchanged, but the position of the sub bone in the main coordinate system (the coordinate system fixed to the main bone) is variable.
A secondary bone is associated with one or more control points. For example, assuming that the position of the control point in the main coordinate system is unchanged, when the position of the secondary bone changes, the position of the control point also changes by the same amount of change.
A surface represented by a set of polygons having each control point as a vertex is a skin. The surface of the character object is covered with a skin. If the position of the control point changes, the shape of the skin also changes. That is, when changing the shape of the character object, the image generating apparatus first moves the position of the sub-bone in the main coordinate system. Next, the position of the control point is also moved based on the change amount of the position of the secondary bone. At this time, the position of the control point after movement is calculated as a position in the parent coordinate system by performing coordinate transformation from the sub-coordinate system to the main coordinate system and from the main coordinate system to the parent coordinate system. That is, if the position of the sub-bone in the main coordinate system is moved, the position of the control point in the parent coordinate system is moved, and as a result, the shape of the skin changes.

According to the present invention, if the position of only the secondary bone associated with the control point that constitutes the skin of the portion of the character object that is to be changed is changed, only the skin of the portion to be changed is changed. Is deformed. That is, only a desired portion of the character object can be easily deformed, and the portion that is not desired to be deformed is not affected (not deformed).
For example, there is a comical expression method in which a part of the character (for example, palm) or all of the character is crushed by so-called clay animation, etc. It becomes possible. In other words, if you associate multiple secondary bones in advance with the main bones that make up the character object, and then associate control points with each secondary bone, you can simply change the position of the secondary bone near the part you want to deform. Only the desired part can be deformed.

For example, the position of the control point associated with the secondary bone in the secondary coordinate system may be constant.
According to the present invention, since the position of the control point is always moved by the same amount as the movement amount of the secondary bone, the skin can be deformed more easily. For example, when a plurality of control points are associated in advance with a certain sub-bone to be moved, all the control points associated with the sub-bone may be moved by the same movement amount. Then, for a polygon composed only of control points associated with the sub-bone, it is only necessary to move the position without changing the shape, and the character object can be deformed more easily.

For example, a plurality of sub-bones are associated with the main bone, and different control points are associated with the sub-bones.
In addition, the storage unit stores the position of the control point associated with the sub bone in the sub coordinate system fixed to the sub bone for each of the sub bones.
Then, the calculation unit calculates the position of the main bone in the parent coordinate system, the position of the sub bone in the main coordinate system, and the control point associated with each of the sub bones in the sub coordinate system. Each position of the control point in the parent coordinate system may be calculated based on the position.
According to the present invention, since a plurality of control points are associated with one sub-bone, the positions of many control points can be changed at a time. That is, a set of a plurality of polygons can be moved together, and a wider skin can be deformed at a time.

The calculation unit is a control point (hereinafter referred to as “tip control point”) having the largest coordinate value in a one-dimensional coordinate system (hereinafter referred to as “movement coordinate system”) having an axis whose positive direction is the movement direction of the sub-bone. The amount of movement is
(A) If smaller than a predetermined value, calculate the position where each of the control points is moved so that the position of the control point associated with the sub-bone in the sub-coordinate system is constant,
(B) If larger than a predetermined value, the position of the tip control point in the sub-coordinate system is made constant, and the position of the control point other than the tip control point moved in the sub-coordinate system is calculated.
You may do it.
For example, it is assumed that the character object to be deformed has a three-dimensional shape, the shape is variable, and an image is generated that shows how the character object is crushed by a hard wall or floor. In this example, the predetermined value is the shortest distance from the character object to the surface. Some of the control points are closest to the surface (ie, the tip control point), next closest to the surface, and most distant from the surface.
When the character object moves in a certain direction of the surface, the amount of change in the position of the control point is the same as the amount of change in the position of the sub-bone until the character object touches the surface (that is, in the case of (a) above). is there. For example, if the secondary bone is translated, the control point is also translated by the same displacement. For example, if the secondary bone rotates, the control point also rotates by the same angle.
Further, if the character object continues to move in the direction with the plane, the character object eventually collides with the plane. In other words, the tip control point contacts the surface. When the character object collides with the surface (that is, in the case of (b) above), the position of the tip control point in the sub-coordinate system is fixed without changing any more. Other control points continue to move in the same direction of movement. When the control point closest to the surface eventually comes into contact with the surface, the position of the second control point is fixed without changing any more. Similarly, the positions of the control points close to the third, fourth, etc. are eventually fixed, and finally the positions of the control points associated with the sub-bone to be moved are all fixed. The character object does not sink deeper than the surface. Therefore, it is possible to change a character object having a three-dimensional shape in the same manner as an expression method that makes a mess in clay animation.

The calculation unit
(B1) When the position of the control point other than the tip control point in the moving coordinate system becomes equal to the position of the tip control point in the moving coordinate system, the sub-coordinate system of the control point other than the tip control point The position at may also be constant.
According to the present invention, the position where each control point is fixed, such as the control point closest to the surface (tip control point), the control point closest to the surface, and the like is a position in contact with the surface. That is, the control points associated with the secondary bone to be moved are deformed flat along the surface. Therefore, the character object having a three-dimensional shape is deformed flat along the surface, and the shape change can be performed in the same manner as an expression method that becomes a mess in clay animation.

The storage unit may further store the orientation of the main bone in the parent coordinate system and the orientation of the sub-bone in the main coordinate system.
Then, the calculation unit, based on the position and orientation of the main bone in the parent coordinate system, the position and orientation of the sub bone in the main coordinate system, and the position of the control point in the sub coordinate system, The position of the control point in the parent coordinate system may be calculated.
According to the present invention, the secondary bone can be defined as a bone whose posture can be arbitrarily changed. For example, the shape of the secondary bone can be a point, a line segment or a curve having an arbitrary length, or the like. Further, it may be a two-dimensional shape such as a plane or a curved surface, or may be a three-dimensional shape such as a cylinder, a prism, a cone, a pyramid, a sphere, or a polyhedron. Accordingly, the secondary bone can be rotated as well as translated, and the skin can be changed into various shapes.

The updating unit may update the position by moving the position of the sub-bone in the main coordinate system by at least one of parallel movement and rotational movement.
According to the present invention, the image generating apparatus can translate or rotate the secondary bone. For example, if the position of the control point in the sub-coordinate system is fixed, the position of the control point is also moved by the same amount as the movement amount due to the parallel or rotational movement of the sub-bone. Therefore, the character object can be partially or entirely flattened, and a desired portion can be recessed or twisted. In addition, in the rotational movement, not only the central point rotational movement that rotates around a certain point (rotational movement that rotates around the arm), but also the axial rotational movement that rotates around a certain axis (rotation that rolls the cylinder with rollers) Move).

The storage unit may further store the position of the bounding area where the position in the sub-coordinate system is fixed in association with the sub-bone and the position of the obstacle object in the parent coordinate system.
In addition, the image generation device, the position of the main bone in the parent coordinate system, the position of the sub-bone in the main coordinate system, the position of the bounding area in the sub-coordinate system to which the bounding area is assigned, A collision determination unit that determines whether or not the bounding area and the obstacle object collide based on the position of the obstacle object in the parent coordinate system can be further provided.
Then, the update unit may move the position of the bounding area determined to collide with the obstacle object so as to be away from the obstacle object until the bounding area and the obstacle object no longer collide.
Here, the bounding area is used for determination of a collision between the character object and the obstacle object, and is arranged at a preset position. The position of the bounding area in the secondary coordinate system fixed to the secondary bone is unchanged. Typically, the bounding area is arranged to be the same as the surface of the character object or to cover the outside of the surface. For example, if the shape of the bounding area is the same as the surface of the character object, the skin can be handled as it is as a bounding area. When the obstacle object touches the bounding area or enters the bounding area, it is determined that the character object has collided with the obstacle object.
If it is determined that the character object has collided with the obstacle object, the position of the bounding area moves away from the obstacle object. Since the position of the bounding area in the secondary coordinate system is unchanged, the secondary bone also moves away from the obstacle object. That is, as the secondary bone moves, the position of the associated control point also moves, and the shape of the skin changes.
According to the present invention, when the character object is deformed, the image object can be deformed so that the deforming character object matches the shape of the deforming (opposite) character object. If the shape of the bounding area is matched to the shape of the skin, more realistic deformation can be achieved. Also, if the shape of the bounding area is simplified, the deformed deformation can be performed.

The storage unit includes a direction of the main bone in the parent coordinate system, a direction of the sub-bone in the main coordinate system, a direction of the bounding area in the sub-coordinate system, and the obstacle object in the parent coordinate system. The direction may be further stored.
The collision determination unit then fixes the position and orientation of the main bone in the parent coordinate system, the position and orientation of the sub bone in the main coordinate system, and the sub bone fixed to the sub bone to which the bounding area is assigned. Based on the position and orientation of the bounding area in the coordinate system and the position and orientation of the obstacle object in the parent coordinate system, it is determined whether the bounding area and the obstacle object collide. Also good.
According to the present invention, the bounding area can be defined as an area whose posture can be arbitrarily changed. The bounding area can be moved using parallel movement, rotational movement, or a combination of these movements. That is, the secondary bone moves in various ways, and the skin changes into various shapes. For example, it can be deformed by pushing or pulling part or all of the skin according to the shape of the obstacle object, or can be deformed by rotating or twisting.

The bounding area is an average value or a maximum value of the distances between a plurality of control points associated with the secondary bone to which the bounding area is assigned and the secondary bone, and the center is the position of the secondary bone. It may be a sphere.
When a sphere shape is adopted as the bounding area, the collision determination between the character object and the obstacle object is simplified. In addition, the deformation of the skin after the collision is simplified. For example, when a bounding area and an obstacle object collide, if the shape of the obstacle object is also partially approximated as a sphere, the collision determination and shape change before and after the collision can be replaced with a collision model between rigid spheres Become. Also, when treating it as a collision model, if it is assumed that it is a completely elastic collision in classical mechanics, or if these spheres have the same mass or one of them is overwhelmingly large, Calculation of the position of the sphere is easy. That is, the calculation of the position of the control point after the collision is simplified, and the skin can be easily deformed.

The calculation unit changes the scale of the main coordinate system and the sub coordinate system, the position of the main bone in the parent coordinate system, the position of the sub bone in the main coordinate system where the scale is changed, and the control point The position of the control point in the parent coordinate system may be calculated based on the position in the sub-coordinate system where the scale is changed.
For example, if the scales of the main coordinate system and the sub-coordinate system are changed by the same amount, the size of the main bone is enlarged or reduced without changing the shape. As a coordinate system, a three-dimensional coordinate system is generally used, but the scale may be changed for any one or two dimensions. In this case, not only the size of the main bone but also the main bone The shape of the main bone changes with the size.
According to the present invention, the skin can be changed not only by moving the position of the secondary bone but also by changing the size and shape of the main bone. That is, it is possible to provide variations in the way the character object changes. For example, a part or all of the character object can be deformed so as to be enlarged or reduced.

An image generation method according to another aspect of the present invention is an image generation method executed by an image generation apparatus having a storage unit, a calculation unit, an image generation unit, and an update unit, and includes a calculation step, an image generation step, and an update Comprising steps.
In the storage unit, the position of the main bone in the coordinate system (hereinafter referred to as “parent coordinate system”) arranged in the virtual space and the coordinate system (hereinafter referred to as “main coordinate system”) fixed to the main bone. The position of the secondary bone and the position of the control point associated with the secondary bone in a coordinate system fixed to the secondary bone (hereinafter referred to as “sub-coordinate system”) are stored.
In the calculation step, the calculation unit is configured to control the control point based on the position of the main bone in the parent coordinate system, the position of the sub-bone in the main coordinate system, and the position of the control point in the sub-coordinate system. Is calculated in the parent coordinate system.
In the image generation step, the image generation unit determines the shape of the skin based on the calculated position of the control point, and generates an image representing the shape of the skin arranged in the virtual space.
In the update step, the update unit updates the position of the sub-bone in the main coordinate system to change the shape of the skin.
According to the present invention, it is possible to easily generate an image in which only a desired portion is deformed without deforming a portion that the object does not want to deform.

A program according to another aspect of the present invention causes a computer to function as a storage unit, a calculation unit, an image generation unit, and an update unit.
The storage unit includes a position of a main bone in a coordinate system (hereinafter referred to as “parent coordinate system”) arranged in the virtual space, and a subordinate in a coordinate system (hereinafter referred to as “main coordinate system”) fixed to the main bone. The position of the bone and the position of the control point associated with the sub bone in the coordinate system (hereinafter referred to as “sub coordinate system”) fixed to the sub bone are stored.
The calculation unit calculates the parent coordinates of the control point based on the position of the main bone in the parent coordinate system, the position of the sub bone in the main coordinate system, and the position of the control point in the sub coordinate system. Calculate the position in the system.
The image generation unit determines the shape of the skin based on the calculated position of the control point, and generates an image representing the shape of the skin arranged in the virtual space.
The update unit updates the position of the sub-bone in the main coordinate system to change the shape of the skin.
According to the present invention, it is possible to easily generate an image in which only a desired portion is deformed without deforming a portion that the object does not want to deform.

The program of the present invention can be recorded on a computer-readable information storage medium such as a compact disk, flexible disk, hard disk, magneto-optical disk, digital video disk, magnetic tape, and semiconductor memory.
The above program can be distributed and sold via a computer communication network independently of the computer on which the program is executed. The information storage medium can be distributed and sold independently from the computer.

  According to the present invention, an image obtained by deforming an object in a virtual space can be easily generated.

  An embodiment of the present invention will be described. In the following, for ease of understanding, an embodiment in which the present invention is realized using an information processing apparatus for games will be described. However, the following embodiment is for explanation, and the scope of the present invention There is no limit. Therefore, those skilled in the art can employ embodiments in which each or all of these elements are replaced with equivalent ones, and these embodiments are also included in the scope of the present invention.

  FIG. 1 is a schematic diagram showing a schematic configuration of a typical information processing apparatus 100 that performs the function of the image generation apparatus of the present invention by executing a program. Hereinafter, a description will be given with reference to FIG.

  The information processing apparatus 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an interface 104, a controller 105, an external memory 106, a DVD-ROM ( A digital versatile disk-read only memory (107) drive 107, an image processing unit 108, an audio processing unit 109, and a NIC (Network Interface Card) 110 are provided.

  A DVD-ROM storing a game program and data is loaded into the DVD-ROM drive 107 and the information processing apparatus 100 is turned on to execute the program, thereby realizing the image generation apparatus of the present embodiment. Is done.

  The CPU 101 controls the overall operation of the information processing apparatus 100 and is connected to each component to exchange control signals and data. Further, the CPU 101 uses arithmetic operations such as addition / subtraction / multiplication / division, logical sum, logical product, etc. using an ALU (Arithmetic Logic Unit) (not shown) for a storage area called a register (not shown) that can be accessed at high speed. , Logic operations such as logical negation, bit operations such as bit sum, bit product, bit inversion, bit shift, and bit rotation can be performed. In addition, the CPU 101 itself is configured so that saturation operations such as addition / subtraction / multiplication / division for multimedia processing, vector operations such as trigonometric functions, etc. can be performed at a high speed, and those provided with a coprocessor. There is.

  The ROM 102 records an IPL (Initial Program Loader) that is executed immediately after the power is turned on, and when this is executed, the program recorded on the DVD-ROM is read out to the RAM 103 and execution by the CPU 101 is started. The The ROM 102 stores an operating system program and various data necessary for operation control of the entire information processing apparatus 100.

  The RAM 103 is for temporarily storing data and programs, and holds programs and data read from the DVD-ROM and other data necessary for game progress and chat communication. Further, the CPU 101 provides a variable area in the RAM 103 and performs an operation by directly operating the ALU on the value stored in the variable, or temporarily stores the value stored in the RAM 103 in the register. Perform operations such as performing operations on registers and writing back the operation results to memory.

  The controller 105 connected via the interface 104 receives an operation input performed when the user executes a game such as a dance game or a soccer game.

  The external memory 106 detachably connected via the interface 104 stores data indicating game play status (past results, etc.), data indicating game progress, and log of game chat communication using the network ( Data) is stored in a rewritable manner. The user can record these data in the external memory 106 as appropriate by inputting an instruction via the controller 105.

  A DVD-ROM mounted on the DVD-ROM drive 107 stores a program for realizing the game and image data and sound data associated with the game. Under the control of the CPU 101, the DVD-ROM drive 107 performs a reading process on the DVD-ROM loaded therein, reads out necessary programs and data, and these are temporarily stored in the RAM 103 or the like.

  The image processing unit 108 processes the data read from the DVD-ROM by the CPU 101 or an image arithmetic processor (not shown) included in the image processing unit 108, and then processes the processed data on a frame memory ( (Not shown). The image information recorded in the frame memory is converted into a video signal at a predetermined synchronization timing and output to a monitor (not shown) connected to the image processing unit 108. Thereby, various image displays are possible.

  The image calculation processor can execute a two-dimensional image overlay calculation, a transparency calculation such as alpha blending, and various saturation calculations at high speed.

  Also, polygon information arranged in the virtual three-dimensional space and added with various texture information is rendered by the Z buffer method, and the polygon arranged in the virtual three-dimensional space from the predetermined viewpoint position is determined in the direction of the predetermined line of sight It is also possible to perform high-speed execution of operations for obtaining rendered images.

  Further, the CPU 101 and the image arithmetic processor operate in a coordinated manner, so that a character string can be drawn as a two-dimensional image in a frame memory or drawn on the surface of each polygon according to font information defining the character shape. is there.

  Further, by preparing information such as game images in a DVD-ROM and expanding the information in a frame memory, the state of the game can be displayed on the screen.

  The audio processing unit 109 converts audio data read from the DVD-ROM into an analog audio signal, and outputs the analog audio signal from a speaker (not shown) connected thereto. Further, under the control of the CPU 101, sound effects and music data to be generated during the progress of the game are generated, and sound corresponding to this is output from the speaker.

  When the audio data recorded on the DVD-ROM is MIDI data, the audio processing unit 109 refers to the sound source data included in the audio data and converts the MIDI data into PCM data. If the compressed audio data is in ADPCM (Adaptive Differential Pulse Code Modulation) format or Ogg Vorbis format, it is expanded and converted to PCM data. The PCM data can be output by performing D / A (Digital / Analog) conversion at a timing corresponding to the sampling frequency and outputting it to a speaker.

  The NIC 110 is used to connect the information processing apparatus 100 to a computer communication network (not shown) such as the Internet, and is based on the 10BASE-T / 100BASE-T standard used when configuring a LAN (Local Area Network). To connect to the Internet using an analog modem, ISDN (Integrated Services Digital Network) modem, ADSL (Asymmetric Digital Subscriber Line) modem, or cable television line. A cable modem or the like and an interface (not shown) that mediates between these and the CPU 101 are configured.

  In addition, the information processing apparatus 100 uses a large-capacity external storage device such as a hard disk so as to perform the same function as the ROM 102, the RAM 103, the external memory 106, the DVD-ROM attached to the DVD-ROM drive 107, and the like. You may comprise.

Next, a functional configuration of the image generation apparatus 200 according to the present embodiment will be described.
FIG. 2 is a diagram illustrating a functional configuration of the image generation apparatus 200. As shown in the figure, the image generation apparatus 200 includes a storage unit 201, a calculation unit 202, an image generation unit 203, and an update unit 204.

  FIG. 3 is a diagram illustrating an example of a virtual space model of an object using bones, control points, and skins. A global coordinate system 311 is defined in the virtual space. Hereinafter, this coordinate system 311 is referred to as a “parent coordinate system” 311. For example, a Cartesian coordinate system is used as the parent coordinate system 311.

  In this virtual space, main bones 301 (two in the figure, 301A and 301B) are arranged. The length and shape of the main bone 301 are constant. The position and orientation of the main bone 301 are variable. That is, the posture of the main bone 301 changes. The end point 305A2 of the main bone 301A is connected to the end point 305B1 of the main bone 301B. For example, the main bone 301B can rotate with respect to the main bone 301A with the end point 305B1 as the center of rotation.

  The position of the main bone 301 can be expressed as a coordinate value in the parent coordinate system 311. The orientation of the main bone 301 can also be expressed as a direction vector in the parent coordinate system 311. The shape of the main bone 301 is arbitrary.

  The main bone 301A may be connected to another main bone (not shown) at the end point 305A1. Similarly, the main bone 301B may be connected to another main bone (not shown) at the end point 305B2. In order to make the present invention easier to understand, a description will be given using a model composed of two main bones 301A and 301B.

  A coordinate system 312 fixed to the main bone 301A is defined for the main bone 301A. Hereinafter, this coordinate system 312 is referred to as a “main coordinate system” 312. The position of the origin of the main coordinate system 312 matches the position of the end point 305A1 of the main bone 301A. Similarly, another main coordinate system (not shown) can be defined for the main bone 301B. For example, a polar coordinate system is used for the main coordinate system 312.

  For example, by giving a rotation amount in the main coordinate system 312 fixed to the main bone 301A, the relative posture of the other main bone 301B with respect to the one main bone 301A is uniquely determined. The motion of the main bone 301B can be described as a motion in the parent coordinate system 311 by performing coordinate conversion from the main coordinate system 312 to the parent coordinate system 311. The rotation mentioned here includes not only the meaning of “rotating about a certain axis” but also the meaning of “rotating about a certain point”.

  The main bone 301 is associated with sub-bones 302 (three in the figure, 302A, 302B, and 302C). The initial position of the secondary bone 302 (the position before the object is deformed) is a predetermined position on the main bone 301. Each secondary bone 302 is associated with one or more control points 303. In the figure, control points 303A1 to 303A6 are associated with the secondary bone 302A, control points 303B1 to 303B6 are associated with the secondary bone 302B, and control points 303C1 to 303C6 are associated with the secondary bone 302C. Hereinafter, in the figure, this association is expressed by a dotted line.

  That is, the control point 303 is not associated with the main bone 301 as in the prior art, but is associated with the secondary bone 302. One control point 303 is associated with any one secondary bone 302. A plurality of control points 303 may be associated with one secondary bone 302.

  The position and orientation of the secondary bone 302 can be expressed as relative coordinates and relative vectors with respect to the main bone, respectively, using the main coordinate system 312. By performing coordinate conversion from the main coordinate system 312 to the parent coordinate system 311, the position and orientation of the sub-bone 302 using the main coordinate system 312 can be expressed as coordinates and vectors using the parent coordinate system 311, respectively.

  In the secondary bone 302A, a coordinate system 313 fixed to the secondary bone 302A is defined. Hereinafter, this coordinate system 313 is referred to as a “sub coordinate system” 313. The position of the origin of the secondary coordinate system 313 matches the position of the secondary bone 302. Similarly, a secondary coordinate system (not shown) can be defined for each of the secondary bones 302B and 302C. For example, a polar coordinate system is used for the sub-coordinate system 313.

  The position of the control point 303 in the parent coordinate system 311 or the main coordinate system 312 is variable, but the position of the control point 303 in the sub-coordinate system 313 (in other words, the relative position of the control point 303 with respect to the sub-bone 302) is unchanged. is there.

  The shape of the secondary bone 302 is arbitrary. In this figure, the secondary bones 302A, 302B, and 302C are all in the shape of prisms, but this is shown for convenience in understanding the present invention. Typically, the secondary bone 302 can be an imaginary bone that is zero in length and thickness. The secondary bone 302 is used for controlling the position of the control point 303, and the secondary bone 302 is not drawn in the image generated by the image generation apparatus 200.

  When the position of the control point 303 in the parent coordinate system 311 is determined by coordinate conversion, the shape of the skin 304 can be determined based on the position of the control point 303. In the present embodiment, the skin 304 is a collection of polygons (primitives) of minute polygons (typically triangles, quadrangles, etc.), and the control points 303 are vertexes of the polygons in a predetermined association. . The shape of the skin 304 is represented by being divided into polygons and converted into numerical data.

  In addition to the method of determining the shape of the skin 304 using the control points 303 as the vertices of polygons, a method of using NURBS (Non Uniform Rational B Spline) curved surfaces defined by assigning weights to the control points 303 as skins may be used. . In this method, the number of control points 303 can be further increased. In this case, the coordinate value of the point in the skin 304 is determined by the rational polynomial of the two parameters u and v, and the shape of the skin 304 is determined.

  Returning to FIG. 2, the storage unit 201 stores main bone information 251, sub bone information 252, and control point information 253. The RAM 103 and the CPU 101 cooperate to function as the storage unit 201.

  The main bone information 251 is information indicating the position and orientation of the main bone 301 in the parent coordinate system 311 arranged in the virtual space. When there are a plurality of main bones 301, main bone information 251 indicating the position and orientation of each main bone 301 is stored in the storage unit 201. The position is expressed as a coordinate value using the parent coordinate system 311. The direction is represented as a direction vector using the parent coordinate system 311. However, in the case of a model in which the orientation of the main bone 301 is invariable (or can be regarded as invariant), the main bone information 251 may not include information indicating the orientation of the main bone 301.

  The secondary bone information 252 is information indicating the position and orientation of the secondary bone 302 in the main coordinate system 312 fixed to the main bone 301. When there are a plurality of secondary bones 302, secondary bone information 252 indicating the position and orientation of each secondary bone 302 is stored in the storage unit 201. The position and orientation are expressed as coordinate values and direction vectors using the main coordinate system 312, respectively. The position and orientation can be expressed as coordinate values and direction vectors using the parent coordinate system 311 by converting the coordinates from the main coordinate system 312 to the parent coordinate system 311. However, in the case of a model in which the orientation of the secondary bone 302 is not changed (or can be regarded as unchanged), the secondary bone information 252 may not include information indicating the orientation of the secondary bone 302.

  The control point information 253 is information indicating the position of the control point 303 previously assigned to the secondary bone 302 in the secondary coordinate system 313 fixed to the secondary bone 302 for each secondary bone 302. When there are a plurality of control points 303, control point information 253 indicating the position of each control point 303 is stored in the storage unit 201. The position of the control point 303 associated with the secondary bone 302 in the secondary coordinate system 313 fixed to the secondary bone 302 is constant. The position of the control point 303 is expressed as a coordinate value using the main coordinate system 312 by performing coordinate conversion from the sub-coordinate system 313 to the main coordinate system 312. Further, the position of the control point 303 is expressed as a coordinate value using the parent coordinate system 311 by performing coordinate conversion from the main coordinate system 312 to the parent coordinate system 311.

  The calculation unit 202 calculates the position of each control point 303 in the parent coordinate system 311 based on the main bone information 251, the sub bone information 252, and the control point information 253 stored in the storage unit 201. That is, the calculation unit 202 converts the position of the control point 303 in the sub-coordinate system 313 from the sub-coordinate system 313 to the main coordinate system 312, and further converts the coordinates from the main coordinate system 312 to the parent coordinate system 311. The position in the sub coordinate system 313 is converted into the position in the parent coordinate system 311. The CPU 101 and the image processing unit 108 cooperate to function as the calculation unit 202.

  The image generation unit 203 obtains the shape of the skin 304 based on the position of the control point 303 calculated by the calculation unit 202 in the parent coordinate system 311 and generates an image representing the shape of the skin 304 arranged in the virtual space. . The image generation unit 203 generates an image in which the skin 304 is arranged by arranging polygons having the control points 303 as vertices in a predetermined association. For example, when the position or orientation of the sub-bone 302 in the main coordinate system is updated by the update unit 204 to be described later, the image generation unit 203 performs a new operation based on the updated position of the control point 303 calculated by the calculation unit 202. An image in which various skins 304 are arranged is generated. The CPU 101 and the image processing unit 108 cooperate to function as the image generation unit 203.

  The update unit 204 changes the shape of the skin 304 by updating the position and orientation of the sub-bone 302 in the main coordinate system 312 stored in the storage unit 201. The CPU 101, the image processing unit 108, and the RAM 103 cooperate to function as the image generation unit 203.

  FIGS. 4A and 4B are simplified views of the main bone 301, the sub bone 302, the control point 303, and the skin 304 arranged in the virtual space. 4A is before update by the update unit 204, and FIG. 4B is after update by the update unit 204. The secondary bone 302 may be a bone having a length and thickness of zero, that is, a bone having a “point” shape.

  For example, the update unit 204 translates the position of the secondary bone 302B by ΔLX in the X-axis direction, ΔLY in the Y-axis direction, and ΔLZ in the Z-axis direction. At this time, since the position of each control point 303 is fixed to a predetermined position with respect to the secondary bone 302 associated in advance, the update unit 204 controls the control points 303B1, 303B2, associated with the secondary bone 302B. The position of 303B3 is also translated by ΔLX in the X-axis direction, ΔLY in the Y-axis direction, and ΔLZ in the Z-axis direction. The magnitudes of the change amounts ΔLX, ΔLY, ΔLZ of the coordinate values are arbitrary.

  As a result of this translation, the shape of the skin 304 represented by a polygon having each control point 303 as a vertex shown in FIG. 4A is associated with the secondary bone 302 as shown in FIG. 4B. The control points 303B1, 303B2, and 303B3 are indented toward the main bone 301 side. For example, it is possible to generate an image representing a state where the skin is depressed by pressing the skin with a finger.

  Note that the update unit 204 can move the plurality of sub-bones 302 to arbitrary positions separately.

The movement of the secondary bone 302 is not limited to parallel movement.
FIGS. 5A and 5B are simplified views of the main bone 301, the sub bone 302, the control point 303, and the skin 304 arranged in the virtual space. FIG. 5A shows before update by the update unit 204, and FIG. 5B shows after update by the update unit 204. The secondary bone 302 is a bone that is zero in length and thickness. In this example, the update unit 204 changes the control points 303B1 to 303B3 in the X-axis direction by ΔLX and Y-axis directions by changing both the position and orientation of the secondary bone 302B in the secondary coordinate system fixed to the secondary bone 302B. Are translated by ΔLY and ΔLZ in the Z-axis direction, and are rotated by an angle Δθ about one axis (axial rotation movement). Of course, the update unit 204 may perform only rotational movement. The magnitude of the angle Δθ (rotation amount) is arbitrary.

  As a result of this rotational movement of the shaft, the shape of the skin 304 shown in FIG. 5 (a) changes to a shape in which the vicinity of the secondary bone 302B is raised and twisted as shown in FIG. 5 (b). For example, it is possible to generate an image representing a state where the skin is twisted while pinching the skin with a finger.

  The rotational movement is not limited to a movement that rotates around one axis, but may be a movement that rotates around one point (typically the position of the secondary bone 302) (center point rotational movement). FIG. 6A is a diagram illustrating a state after being updated by the update unit 204 from the state of FIG. The secondary bone 302 is a bone that is zero in length and thickness. In this example, the update unit 204 fixes the control points 303B1 to 303B3 by fixing the position of the secondary bone 302B and changing the direction of the secondary bone 302B in the secondary coordinate system fixed to the secondary bone 302B. The point (the position of the secondary bone 302B) is rotated about the angle Δφ. Of course, the update unit 204 may rotate the center point together with at least one of parallel movement and axial rotation movement. The magnitude of the angle Δφ (rotation amount) is arbitrary.

  As a result of the rotational movement of the center point, the shape of the skin 304 shown in FIG. 5A changes to a shape in which the vicinity of the secondary bone 302B is twisted as shown in FIG. 6A. For example, it is possible to generate an image representing a state when the dust cloth is narrowed down.

  The length and thickness of the secondary bone 302 may both be non-zero values. In other words, the shape of the secondary bone 302 is not limited to “points”, and may be a line segment or a curve having an arbitrary length. Further, it may be an arbitrary two-dimensional shape such as a plane or a curved surface, or an arbitrary three-dimensional shape such as a cylinder, a prism, a cone, a pyramid, a sphere, or a polyhedron.

  For example, in FIG. 6B, the sub-bones 302A, 302B, and 302C all have a prismatic shape. The control points 303A1 to 303A3 associated with the secondary bone 302A are associated with (connected to) different parts of the secondary bone 302A. In this figure, the control point 303A1 is connected to the central portion of the secondary bone 302A, the control point 303A2 is connected to the upper end portion of the secondary bone 302A, and the control point 303A3 is connected to the lower end portion of the secondary bone 302A. The same applies to the secondary bones 302B and 302C. However, it is free to connect the control point 303 to which location of the secondary bone 302.

  Even if the secondary bone 302 has a shape other than a point, if each control point 303 is associated (connected) with the same portion of the secondary bone 302 and is translated, rotated axially, or rotated centrally, it is updated. The shape of the skin 304 is substantially the same as that when the secondary bone 302 has a point shape as described above.

  The update unit 204 can control the position of the control point 303 by moving the secondary bone 302 as described above, and can also be used in the parent coordinate system 311 without changing the position of the secondary bone 302 in the primary coordinate system 312. Controls that change the position of the main bone 301 and controls that directly change the position of the control point 303 without changing the position of the sub-bone 302 in the main coordinate system 312 can also be performed. The update unit 204 uses these controls for each game or each game scene.

  Next, image generation processing executed by the above-described units of the image generation apparatus 200 will be described with reference to the flowchart of FIG. By this image generation process, an image in which the shape of the skin 304 is changed is generated. For example, each unit of the image generation apparatus 200 repeatedly executes the image generation process at a predetermined timing such as vertical synchronization (VSync).

  In the following description, for example, as shown in FIG. 8, a virtual space model in which a snake character object 800 is arranged is considered. The surface of the character object 800 is covered with a skin 304 composed of a set of polygons determined by a plurality of control points 303. Sub-bones 302 (three in the figure, 302A, 302B, and 302C) are arranged along the shape of the main bone 301 (for example, the spine). Each secondary bone 302 has at least one control point 303 (in the figure, control point 303A (represented by a circle) associated with the secondary bone 302A) and control point 303B (×) associated with the secondary bone 302B. 3) (represented by a mark) and a control point 303C (represented by a □ mark) associated with the secondary bone 302C.

  First, the image generation unit 203 reads out main bone information 251, sub bone information 252, and control point information 253 stored in the storage unit 201 (step S701). As described above, the main bone information 251 is information indicating the position of the main bone 301 in the parent coordinate system 311. The secondary bone information 252 is information indicating the position of the secondary bone 302 in the main coordinate system 312. The control point information 253 is information indicating the position of the control point 303 assigned to the secondary bone 302 in the secondary coordinate system 313. Note that the orientation of the main bone 301 and the orientation of the sub bone 302 are constant.

  The calculation unit 202 calculates the position of each control point 303 in the sub-coordinate system 313 (step S702). For example, the calculation unit 202 calculates the position of each control point 303 after the change when the character object 800 moves or changes its posture. The calculation unit 202 also calculates the position of the main bone 301 in the parent coordinate system 311 and the position of the sub bone 302 in the main coordinate system 312, but if the positions of the main bone 301 and the sub bone 302 are not changed, These calculations may be omitted.

  For example, as shown in FIG. 9, when the character object 800 is hit by a tire of a car object (not shown), the image generation unit 203 places a tire mark 900 on the ground 820, and the update unit 204 displays the character object 800. Of the control points 303 to be configured, the position of the sub-bone 302B associated with the control point 303B included in the portion that is beaten by the tire is translated in the direction perpendicular to the ground 820.

  Then, since the position of each control point 303B in the sub-coordinate system 313 is fixed, the position of each control point 303B in the main coordinate system 312 is also translated in the same direction as the sub-bone 302.

  The calculation unit 202 converts the position of each control point 303 in the sub-coordinate system 313 to the parent coordinate system 311 (step S703).

  The image generation unit 203 calculates the shape of the skin 304 from the position of each control point 303 calculated in step S703, based on the correspondence previously determined between the vertex of the polygon and the control point 303 (step S703). S704). This correspondence relationship is described in, for example, a table format as data for associating the identification number of the control point 303 with the polygon identification number, and is stored in the storage unit 201 in advance.

  The update unit 204 updates the main bone information 251, the sub bone information 252, and the control point information 253 (step S705). That is, the update unit 204 sets the main bone information 251 and the sub bones with the positions of the main bone 301, the sub bone 302, and the control point 303 calculated by the calculation unit 202 in step S702 as new positions. Information 252 and control point information 253 are generated, and the storage unit 201 is updated.

  Then, the image generation unit 203 determines the shape of the skin 304 using the updated position of each control point 303 as the vertex of each polygon, and generates an image representing the shape of the skin 304 (step S706). The image generation unit 203 translates a polygon (polygon of a portion worn by the tire) composed only of the control point 303B associated with the secondary bone 302B to be moved, and includes the control point 303B at a part of the vertex. It is only necessary to change the shape of the polygon (the portion on both ends of the tire mark 810).

  According to the present embodiment, the image generation apparatus 200 does not need to recalculate the positions and shapes of all the skins 304, and moves polygons that are formed only of the control points 303 to be moved without changing the shape. Therefore, an image obtained by deforming an object can be generated more easily.

  For example, in a clay animation in which the subject is made of clay, a comical expression method that makes a character sneak up when the character hits something or falls is used. By changing the direction of the position of the secondary bone 302 instead of controlling the position of the control point 303, it is possible to easily generate an image in which the character is deformed as if it is a clay animation in the three-dimensional virtual space. it can. For example, as shown in FIG. 8, it is possible to easily generate an image representing a state where a character object 800 stroking the ground is hit by a car and becomes crushed as shown in FIG.

(Embodiment 2)
Next, other embodiments of the present invention will be described. In the above-described embodiment, the position of the control point 303 in the sub-coordinate system 313 fixed to the sub-bone 302 is constant, but this embodiment does not change if the movement amount of the position of the control point 303 is smaller than the threshold value. It is different in that it is variable if it is large.

  10 to 13 are diagrams showing the main bone 301, the sub bone 302, the control point 303, and the skin 304 of the virtual space model handled in the present embodiment. The surface represented by the skin 304 and the collision surface (typically, the ground, a wall, etc.) 1020 form a non-zero angle Δψ. The update unit 204 moves the secondary bone 302 with the direction toward the collision surface 1020 as the movement direction. In addition, in order to make the present invention easier to understand, it is assumed that the control points 303 before the start of movement are arranged in a grid of equally spaced α.

  In the present embodiment, as an example, only the secondary bone 302B among the secondary bones 302A to 302C is translated. The sub-bone 302B has three types of control points 303B1, 303B2, and 303B3 in the order closer to the collision surface 1020. In other words, in a one-dimensional coordinate system (hereinafter referred to as “moving coordinate system”) 314 having an axis with the moving direction of the secondary bone 302 as a positive direction, the control points 303B1, 303B2, and 303B3 are in descending order of coordinate values. Be placed. In the movement coordinate system 314, “closest to the collision surface 1020” means that the coordinate value of the position in the movement coordinate system 314 is the largest.

  FIG. 14 is a flowchart for explaining details of the process in step S702 described above.

  In step S702 described above, the calculation unit 202 calculates the positions of the control points 303B1 to B3 that have been moved by the same amount as the movement amount of the secondary bone 302B in the movement coordinate system 314. Then, the coordinate transformation from the moving coordinate system 314 to the sub-coordinate system 313 is performed, and the position of each control point 303 in the sub-coordinate system 313 is calculated (step S1401).

  Note that if one axis of the sub-coordinate system 313 and the axis of the moving coordinate system 314 are matched, coordinate conversion from the moving coordinate system 314 to the sub-coordinate system 313 can be omitted.

  Next, the updating unit 204 determines whether or not the movement amount of the control point 303B1 (tip control point) closest to the collision surface 1020 is smaller than a predetermined threshold value Δλ (step S1402).

  Here, FIG. 11 is a diagram illustrating a virtual space model when the control point 303B1 is moved by the threshold value Δλ. The predetermined threshold value Δλ is typically the minimum value of the distance between the skin 304 and the collision surface 1020 before starting movement. For example, when a certain character object falls on the ground, the collision plane 1020 is the ground, and the shortest distance between the surface of the falling character object and the ground is Δλ.

  When the movement amount of the control point 303B1 (or the movement amount of the secondary bone 302B) is smaller than the threshold value Δλ (step S1402; YES), the update unit 204 returns to step S1401 and continuously moves the secondary bone 302B in the movement direction 1050. . The calculation unit 202 moves the control point 303 associated with the moving secondary bone 302 by the same amount as the movement amount of the secondary bone 302.

  When the movement amount of the control point 303B1 (or the movement amount of the secondary bone 302B) is not smaller than the threshold value Δλ (step S1402; NO), the calculation unit 202 sets the control point 303B1 closest to the collision surface 1020 to the current position. It is fixed (step S1403). That is, the control point 303B1 is not moved any further. For example, when a character object falls on the ground and the part closest to the collision surface 1020 of the character object touches the ground, the part in contact with the ground is fixed at that position and does not sink into the ground.

  Then, the update unit 204 moves the secondary bone 302B, and the calculation unit 202 moves the other control points 303B2 and 303B3 that are not fixed in the movement direction 1050 (step S1404). The calculation unit 202 calculates the positions of the control points 303B2 and 303B3 that are moved by the same amount as the movement amount of the secondary bone 302B in the movement coordinate system 314. Then, the coordinate transformation from the moving coordinate system 314 to the sub-coordinate system 313 is performed, and the position of each control point 303 in the sub-coordinate system 313 is calculated.

  FIG. 12 is a diagram illustrating a virtual space model when the control point 303B1 is fixed and the other control points 303B2 and 303B3 are further moved. At this time, the control point 303B1 has moved by Δλ, but 303B2 and 303B3 have moved by the amount represented by the following [Equation 1].

  Movement amount = Δλ + Δα × sin Δψ [Equation 1]

  Further, the calculation unit 202 determines whether or not the position of the control point 303B2 next to the collision surface 1020 is the same as the position of the fixed control point 303B1 (tip control point) in the moving coordinate system 314 (step S1405). That is, it is determined whether or not the control point 303B2 is in contact with the collision surface 1020.

  If the position of the control point 303B2 in the moving coordinate system 314 is not the same as the position of the control point 303B1, that is, if the control point 303B2 is not in contact with the collision surface (step S1405; NO), the updating unit 204 returns to step S1404 and continues. The secondary bone 302B is moved in the movement direction 1050. The calculation unit 202 moves each control point 303 that is not fixed by the same movement amount as that of the secondary bone 302. That is, among the control points 303B1, 303B2, and 303B3 associated with the secondary bone 302B, the control point 303B1 that has already been fixed in step S1403 is not moved.

  On the other hand, if they are the same (step S1405; YES), the calculation unit 202 determines whether or not all the control points 303B1, 303B2, and 303B3 associated with the movement-target secondary bone 302B have been fixed (step S1406). . In FIG. 12, the control points 303B2 and 303B3 are not yet fixed.

  When all the control points 303 are not yet fixed (step S1406; NO), the calculation unit 202 fixes the position of the control point 303B2 next to the collision surface 1020 in the moving coordinate system 314 to the current position ( Step S1407).

  Then, the update unit 204 returns to step S1404 to further move the secondary bone 302B, and the calculation unit 202 moves the other unfixed control point 303B3 by the same amount in the movement direction 1050. That is, the calculation unit 202 calculates the position of the control point 303B3 that has been moved by the same amount as the movement amount of the secondary bone 302B in the movement coordinate system 314. Then, the coordinate transformation from the moving coordinate system 314 to the sub-coordinate system 313 is performed, and the position of each control point 303 in the sub-coordinate system 313 is calculated.

  As a result of repeating the processing of steps S1404 to S1407 until the positions of all the control points 303 are fixed, the movement amount of each control point 303 in the movement coordinate system 314 is expressed by the following [Equation 2] to [Equation 4]. .

Movement amount of control point 303B1 (tip control point) = Δλ (Equation 2)
Movement amount of control point 303B2 = Δλ + Δα × sin Δψ (Equation 3)
Movement amount of control point 303B3 = Δλ + 2 × Δα × sin Δψ [Equation 4]

  FIG. 13 is a diagram illustrating the virtual space model after moving all the control points 303B associated with the secondary bone 302B. Of the shape of the skin 304 that is inclined by the angle Δψ with respect to the collision surface 1020 before the start of movement, a portion represented by a polygon composed only of the control point 303B associated with the secondary bone 302B is It overlaps parallel to the collision surface 1020.

  The collision surface 1020 is not limited to a flat surface, and may be a curved surface having an arbitrary shape. The updated skin 304 has a shape along a curved surface of an arbitrary shape (deformed to match the shape of the curved surface). Further, the collision surface 1020 may be a surface constituting a part of a character object having an arbitrary shape.

  When the deformed character object is returned to the original shape, the updating unit 204 may return the position and orientation of the sub bone 302 to a predetermined initial position on the main bone 301. For example, if the above steps are executed in the reverse order, the scrambled character object can be returned to the original by reverse motion as if to open a real-world 3D picture book (a picture book that pops out and a picture book).

  According to the present embodiment, the image generating apparatus 200 can easily deform an arbitrary character object having a three-dimensional shape as if it is expressed by clay animation without requiring complicated calculation. Can do.

  For example, assume that a three-dimensional character object 1510 arranged in a three-dimensional virtual space is falling in a moving direction 1530 toward the ground 1520 as shown in FIG. The surface of the character object 1510 is covered with a skin 304 composed of a plurality of polygons defined by a plurality of control points 303. During the fall until the character object 1510 hits the ground 1520, the main bone 301, the secondary bone 302, the control point 303, and the skin 304 move in parallel in the movement direction 1520. When the character object 1510 hits the ground 1520, the update unit 204 moves the secondary bone 303 little by little in the moving direction 1530, and the calculation unit 202 sets the control point 303 associated with the secondary bone 302 to [Equation 2] to [Equation 4]. ] And move them by different movement amounts. As a result, the shape of the skin 304 becomes a flat shape along the ground 1520, and the character object 1510 is squashed on the ground 1520 as shown in FIG.

(Embodiment 3)
Next, other embodiments of the present invention will be described. In the above-described embodiment, a collision between a character object and a plane is considered, but in this embodiment, a collision between a certain character object and another character object (hereinafter referred to as an “obstacle object”) is considered.

  FIG. 16 is a diagram illustrating a functional configuration of the image generation apparatus 200 according to the present embodiment. The image generation device 200 further includes a collision determination unit 205.

  FIG. 17A is a diagram illustrating a virtual space model handled in the present embodiment. In the virtual space, for example, a character object 1710 in the shape of a boxing sandbag and an obstacle object 1720 in the shape of a boxer's glove are arranged. When the obstacle object 1720 moves in the movement direction 1730, the character object 1710 and the obstacle object 1720 eventually collide.

  The character object 1710 is covered with a skin 304 composed of polygons whose apexes are a plurality of control points 303 associated with the sub-bones 302 arranged along the main bone 301.

  FIG. 17 (b) is an enlarged view of the circle in FIG. 17 (a). The bounding area 1750 is an area set in advance to determine whether or not the character object 1710 and the obstacle object 1720 collide. Typically, the shape of bounding area 1750 matches part or all of the shape of character object 1710. However, the bounding area 1750 is slightly larger than the outer shape of the character object 1710, and may have a schematic shape that covers the skin 304 from the outside, or a deformed shape that represents the approximate shape of the character object 1710. The position of the bounding area 1750 in the sub-coordinate system 313 is constant. In this figure, the shape of the bounding area 1750 coincides with a part of the shape of the skin 304.

  The storage unit 201 further stores obstacle information 254 and bounding area information 255.

  The obstacle information 254 is information indicating the position and orientation of the obstacle object 1720 in the parent coordinate system 311 arranged in the virtual space. The position is expressed as a coordinate value using the parent coordinate system 311. The direction is represented as a direction vector using the parent coordinate system 311. However, in the case of a model in which the orientation of the obstacle object 1720 is unchanged (or can be regarded as unchanged), the obstacle information 254 may not include information indicating the orientation of the obstacle object 1720.

  The bounding area information 255 is information indicating the position and orientation of the bounding area 1750 in which the position in the secondary coordinate system 313 is fixed in association with the secondary bone 302. However, in the case of a model in which the direction of the bounding area 1750 is unchanged (or can be regarded as unchanged), the bounding area information 255 may not include information indicating the direction of the bounding area 1750.

  The collision determination unit 205 determines whether or not the bounding area 1750 and the obstacle object 1720 collide based on the main bone information 251, the sub bone information 252, the obstacle information 254, and the bounding area information 255. . For example, in the obstacle determination unit 205, any coordinate value of a predetermined representative point (not shown) included in the bounding area 1750 is surrounded by the skin that forms the surface of the obstacle object 1750 (the surface of the obstacle object 1720). It is determined by whether or not it is in the area. As shown in FIG. 17B, when the shape of the bounding area 1750 coincides with a part of the shape of the skin 304, the control point 303 may be used as a predetermined representative point.

  The update unit 204 moves the position of the bounding area 1750 that has been determined to collide with the obstacle object 1720 so as to move away from the obstacle object 1720 until the bounding area 1750 and the obstacle object 1720 no longer collide. That is, the update unit 204 moves the bounding area 1750 so that the space occupied by the obstacle object 1720 and the space occupied by the bounding area 1750 do not overlap. Since the position of the bounding area 1750 in the secondary coordinate system 313 is constant, the update unit 204 moves the secondary bone 302 by the same movement amount.

  FIG. 18A shows a state in which the update unit 204 moves the secondary bone 302 from the state shown in FIG. 17A when the collision determination unit 205 determines that the bounding area 1750 and the obstacle object 1720 collide. FIG. FIG. 18B is an enlarged view of the circle in FIG. The update unit 204 moves the secondary bone 302 until the bounding area 1750 and the obstacle object 1720 do not collide. In FIG. 18A, the update unit 204 translates the secondary bones 302B, 302C, and 302D by Δξ in the positive direction of the moving coordinate system 314, respectively. Since the position of the control point 303 in the sub-coordinate system 313 is constant, the control points 303B, 303C, and 303D are also translated by Δξ.

  However, the update unit 204 may translate the secondary bone 302 in another direction instead of translating it in the traveling direction of the obstacle object 1720.

  For example, as shown in FIGS. 19A and 19B, a spherical bounding area 1750 centered on the position of the secondary bone 302D, and an approximate obstacle 1725 that can be obtained by approximating the obstacle object 1720 partially in a sphere. And a spherical collision model between the bounding area 1750 and the approximate obstacle 1725 is considered. Here, the update unit 204 treats both the bounding area 1750 and the approximate obstacle 1725 as rigid bodies. The radius of the sphere representing the bounding area 1750 is, for example, the average or maximum value of the distance between the control point 303D associated with the secondary bone 302D to which the bounding area 1750 is assigned and the secondary bone 302D. The radius of the sphere representing the approximate obstacle 1725 is set to a predetermined value or the same value as the radius of the sphere representing the bounding area 1750, for example.

  In considering the rigid sphere collision model, in order to simplify the calculation of the positions of the bounding area 1750 and the approximate obstacle 1725 before and after the collision, the mass μA of the sphere representing the bounding area 1750 is represented by the sphere representing the approximate obstacle 1725. And the radius γB of the sphere representing the approximate obstacle 1725 is preferably set to the same value as the radius γA of the sphere representing the bounding area 1750 (γA = γB).

  Alternatively, the mass μB of the sphere representing the approximate obstacle 1725 is sufficiently (overwhelmingly) larger than the mass μA of the sphere representing the bounding area 1750 (μA << μB), and the sphere representing the approximate obstacle 1725 The radius γB is preferably set to the same value as the radius γA of the sphere representing the bounding area 1750 (γA = γB). In this case, the moving direction 1730 of the obstacle object 1720 can be regarded as unchanged after the collision.

  When the bounding area 1750 and the approximate obstacle 1725 collide, the calculation unit 202 calculates the position of the secondary bone 302D in the main coordinate system 312 using a rigid sphere collision model that is generally handled by classical mechanics. Then, the calculation unit 202 calculates the position of the control point 303 in the parent coordinate system 311 by performing coordinate conversion from the sub-coordinate system 313 to the parent coordinate system 311. For example, the position of the secondary bone 302D after the collision moves by Δξ1 in the horizontal direction and Δξ2 in the vertical direction. Similarly, the position of each control point 302D associated with the secondary bone 302D is also moved by Δξ1 in the horizontal direction and Δξ2 in the vertical direction.

  The calculation unit 202 applies the rigid sphere collision model to all the secondary bones 302 and calculates the positions of all the control points 303 in the same manner.

  Note that the update unit 204 may move the secondary bone 302 by axial rotation movement or center point rotation movement instead of or in addition to the parallel movement.

  The entire area occupied by the sphere representing the approximate obstacle 1725 before the collision is preferably on the opposite side of the bounding area 1750 with respect to the surface of the obstacle object 1720.

  According to the present embodiment, the image generation apparatus 200 can easily generate images representing before and after the collision between objects having arbitrary shapes, particularly an image in which the object is deformed after the collision. When the position of the main bone 301 is moved by associating the control point with the main bone 301 as in the prior art, the part of the object that is not desired to be deformed is also deformed. When the position of the secondary bone 302 is moved in association with each other, it is possible to deform only the portion of the object that is desired to be deformed and not to deform the portion that is not desired to be deformed.

  FIG. 20A is a diagram illustrating a virtual space model in the case where the skeleton is configured by applying the conventional technique as it is and changing the main bone 301 from one to five. For example, when the object is deformed so as to be recessed near the middle, the object is deformed so that the entire object is bent as well as the punched part as shown in FIG. This can be said to be an expression technique closer to the phenomenon in the real world. However, there are cases, such as clay animation, in which the deformed part can be emphasized more by expressing the character flatly so that it cannot be in the real world, and there are cases where it can be expressed interestingly exaggeratedly. The present invention is particularly effective when used in such a case.

(Embodiment 4)
Next, other embodiments of the present invention will be described. In each of the above-described embodiments, the main bone 301 has a fixed shape. However, the size, length, shape, etc. of the main bone 301 may be variable. This will be described in detail below.

  The storage unit 201 according to the present embodiment stores, as main bone information 251, information indicating the enlargement / reduction ratio P of the main bone 301 in addition to information indicating the position and orientation of the main bone 301 in the parent coordinate system 311 arranged in the virtual space. Is further memorized.

  For example, when the object is not in contact with or collided with another object (normal state), the enlargement / reduction ratio P of the main bone 301 is set to 1. On the other hand, in a state where the object is in contact with or collides with another object (contact state / collision state), the calculation unit 202 changes the scaling ratio P. However, P> 0.

  FIG. 21 is a diagram illustrating a virtual space model in a normal state. The snake object 2100 includes three main bones 301A, 301B, and 301C in a region 2110, and each main bone 301 is associated with one or more sub-bones 302. For example, three sub-bones 302B1, 302B2, and 302B3 are associated with the main bone 301B. Furthermore, one or more control points 303 are assigned to each secondary bone 302. For example, three control points 303B1, 303B2, and 303B3 are assigned to the secondary bone 302B.

  FIG. 22 is a diagram illustrating a virtual space model in contact with a suction port such as a vacuum cleaner. The snake object 2100 is deformed so as to be sucked into the suction port. At this time, the calculation unit 202 changes the expansion / contraction rate P of the main bone 301 according to the magnitude of the external force 2120 (in this case, attractive force). For example, the larger the external force 2120, the smaller the expansion / contraction rate. That is, the size of the main bone 301 is reduced as it is drawn more strongly into the suction port. In this figure, the calculation unit 202 reduces the main bone 301B by P times and translates the positions of the sub-bones 302B1, 302B2, and 302B3 in the main coordinate system 312 upward. As a result, the snake object 2100 is deformed so as to sag (pull) as it approaches the suction port.

  However, the relative positional relationship of the sub-bone 302 with respect to the main bone 301 is not changed, and the calculation unit 202 enlarges / reduces the scale of the entire main coordinate system 312. Further, the relative positional relationship of the control point 303 with respect to the secondary bone 302 is not changed, and the calculation unit 202 expands or contracts the scale of the entire secondary coordinate system 313 by the same amount. In step S703 described above, the calculation unit 202 may change the scales of the main coordinate system 312 and the sub-coordinate system 313 and coordinate-convert the position of each control point 303 in the sub-coordinate system 313 to the parent coordinate system 311.

  Of course, the direction, size, and type of the external force 2120 can be arbitrarily changed. Further, instead of changing the enlargement / reduction ratio according to the magnitude of the force applied to the object, the enlargement / reduction ratio may be changed according to the moving speed or acceleration of the object or the like.

  In the present embodiment, the scale of the entire main coordinate system 312 or the entire sub-coordinate system 313 is changed, but a part of the scale may be changed instead of the entire coordinate system. For example, when a Cartesian coordinate system is used, the scales in the X-axis direction and the Y-axis direction are not changed, but only the scale in the Z-axis direction may be scaled.

  According to the present embodiment, not only the position of the secondary bone 302 in the main coordinate system 312 can be changed, but also the size and shape of the main bone 301 can be changed, so that various variations can be made in how to deform the object. Can do.

  The present invention is not limited to the above-described embodiments, and various modifications and applications are possible. Moreover, it is also possible to freely combine the constituent elements of the above-described embodiments.

  A program for operating the image generating apparatus 200 as all or part of the apparatus is stored and distributed in a computer-readable recording medium such as a memory card, CD-ROM, DVD, or MO (Magneto Optical disk). May be installed in another computer and operated as the above-described means, or the above-described steps may be executed.

  Furthermore, the program may be stored in a disk device or the like included in a server device on the Internet, and may be downloaded onto a computer by being superimposed on a carrier wave, for example.

  As described above, according to the present invention, it is possible to provide an image generation apparatus, an image generation method, and a program suitable for easily generating an image obtained by deforming an object in a virtual space.

It is a figure which shows schematic structure of the typical information processing apparatus with which the image generation apparatus of this embodiment is implement | achieved. It is a figure for demonstrating the functional structure of an image generation apparatus. FIG. 6 is a diagram for explaining main bones, sub bones, control points, and skins of the virtual space model in the first embodiment. (A) It is an example of the image showing a mode before an update part moves a subbone. (B) It is an example of the image showing a mode after the update part translated the subbone. (A) It is an example of the image showing a mode before an update part moves a subbone. (B) It is an example of the image showing a mode after an update part moves a secondary bone in parallel and axially moves it. (A) It is an example of the image showing the mode after an update part rotationally moves the subbone center point. (B) It is an example of the image showing a mode after the renewal part rotated and moved the secondary bone center point when the shape of the secondary bone is a prism. It is a flowchart for demonstrating an image generation process. It is a figure showing the main bone, the subbone, the control point, and the skin before the update by the update part. It is a figure showing the main bone, the subbone, the control point, and the skin after the update by the update part. FIG. 10 is a diagram for explaining a virtual space model (part 1) in the second embodiment. It is a figure for demonstrating the virtual space model (the 2) in Embodiment 2. FIG. It is a figure for demonstrating the virtual space model (the 3) in Embodiment 2. FIG. It is a figure for demonstrating the virtual space model (the 4) in Embodiment 2. FIG. It is a flowchart for demonstrating the process in which an update part updates the position of a control point. (A) It is a figure showing the character object falling toward the ground. (B) It is a figure showing the character object after falling on the ground. FIG. 10 is a diagram for describing a functional configuration of an image generation apparatus according to a third embodiment. (A) And (b) is a figure for demonstrating the virtual space model before the collision in Embodiment 3. FIG. (A) And (b) is a figure for demonstrating the virtual space model after the collision in Embodiment 3. FIG. (A) And (b) is a figure for demonstrating the virtual space model which employ | adopted the rigid spherical collision model in Embodiment 3. FIG. (A) And (b) is a figure for demonstrating the virtual space model using the conventional method. FIG. 10 is a diagram for explaining a virtual space model in a normal state according to a fourth embodiment. It is a figure for demonstrating the virtual space model of the contact state in Embodiment 4. FIG.

Explanation of symbols

100 Information processing apparatus 101 CPU
102 ROM
103 RAM
104 Interface 105 Controller 106 External Memory 107 DVD-ROM Drive 108 Image Processing Unit 109 Audio Processing Unit 110 NIC
200 Image Generation Device 201 Storage Unit 202 Calculation Unit 203 Image Generation Unit 204 Update Unit 205 Collision Determination Unit 251 Main Bone Information 252 Secondary Bone Information 253 Control Point Information 254 Obstacle Information 255 Bounding Area Information 301 Main Bone 302 Sub Bone 303 Control Point 304 Skin 311 Parent Coordinate System 312 Main Coordinate System 313 Sub Coordinate System 314 Moving Coordinate System

Claims (14)

The position of the main bone in the coordinate system (hereinafter referred to as “parent coordinate system”) arranged in the virtual space, and the position of the sub bone in the coordinate system fixed to the main bone (hereinafter referred to as “main coordinate system”) The position of the control point associated with the sub-bone in the coordinate system fixed to the sub-bone (hereinafter referred to as “sub-coordinate system”) and the position in the sub-coordinate system associated with the sub-bone are fixed. A storage unit for storing the position of the bounding area and the position of the obstacle object in the parent coordinate system ;
The position of the main bone in the parent coordinate system, the position of the sub bone in the main coordinate system, the position of the bounding area in the sub coordinate system to which the bounding area is assigned, and the obstacle in the parent coordinate system A collision determination unit that determines whether or not the bounding area and the obstacle object collide based on the position of the object object;
Based on the position of the main bone in the parent coordinate system, the position of the sub bone in the main coordinate system, and the position of the control point in the sub coordinate system, the position of the control point in the parent coordinate system is determined. A calculation unit for calculating,
An image generation unit that determines the shape of the skin according to the calculated position of the control point, and generates an image representing the shape of the skin arranged in the virtual space;
Update the position of the secondary bone in the main coordinate system, change the shape of the skin, and change the position of the bounding area determined to collide with the obstacle object until the obstacle object no longer collides. as away from the obstacle object, an update unit you move along with the auxiliary bones,
An image generation apparatus comprising: The image generation apparatus according to claim 1,
The position of the control point associated with the secondary bone in the secondary coordinate system is constant,
An image generation apparatus characterized by that. The image generation apparatus according to claim 1,
A plurality of sub-bones are associated with the main bone,
A different control point is associated with each of the secondary bones,
The storage unit stores, for each of the sub-bones, a position of a control point associated with the sub-bone in a sub-coordinate system fixed to the sub-bone.
The calculation unit calculates the position of the main bone in the parent coordinate system, the position of the sub bone in the main coordinate system, and the position of the control point associated with each of the sub bones in the sub coordinate system. And calculating the respective position of the control point in the parent coordinate system based on
An image generation apparatus characterized by that. The image generation device according to claim 3,
The calculation unit has a control point (hereinafter referred to as “tip control point”) having the largest coordinate value in a one-dimensional coordinate system (hereinafter referred to as “movement coordinate system”) having an axis whose positive direction is the movement direction of the secondary bone. The amount of movement is
(A) If smaller than a predetermined value, calculate the position where each of the control points is moved so that the position of the control point associated with the sub-bone in the sub-coordinate system is constant,
(B) If larger than a predetermined value, the position of the tip control point in the sub-coordinate system is made constant, and the position of the control point other than the tip control point moved in the sub-coordinate system is calculated.
An image generation apparatus characterized by that. The image generation apparatus according to claim 4,
The calculation unit further includes:
(B1) When the position of the control point other than the tip control point in the moving coordinate system becomes equal to the position of the tip control point in the moving coordinate system, the sub-coordinate system of the control point other than the tip control point The position at is also constant,
An image generation apparatus characterized by that. The image generation apparatus according to any one of claims 1 to 5,
The storage unit further stores the orientation of the main bone in the parent coordinate system and the orientation of the sub-bone in the main coordinate system,
The calculation unit performs the control based on the position and orientation of the main bone in the parent coordinate system, the position and orientation of the sub bone in the main coordinate system, and the position of the control point in the sub coordinate system. Calculate the position of the point in the parent coordinate system,
An image generation apparatus characterized by that. The image generation apparatus according to claim 6,
The update unit updates the position by moving the position of the sub-bone in the main coordinate system by at least one of parallel movement and rotational movement.
An image generation apparatus characterized by that. The image generation apparatus according to claim 1 ,
The storage unit includes an orientation of the main bone in the parent coordinate system, an orientation of the sub bone in the main coordinate system, an orientation of the bounding area in the sub coordinate system, and the parent coordinate system of the obstacle object. Remember the orientation of
The collision determination unit includes the position and orientation of the main bone in the parent coordinate system, the position and orientation of the sub bone in the main coordinate system, and the sub coordinates fixed to the sub bone to which the bounding area is assigned. Determining whether or not the bounding area and the obstacle object collide based on the position and orientation of the bounding area in the system and the position and orientation of the obstacle object in the parent coordinate system;
An image generation apparatus characterized by that. The image generation apparatus according to claim 1 , wherein:
The bounding area is an average value or a maximum value of the distances between a plurality of control points associated with the secondary bone to which the bounding area is assigned and the secondary bone, and the center is the position of the secondary bone. Is a sphere,
An image generation apparatus characterized by that. The image generation apparatus according to any one of claims 1 to 9 ,
The calculation unit changes the scale of the main coordinate system and the sub coordinate system, the position of the main bone in the parent coordinate system, the position of the sub bone in the main coordinate system where the scale is changed, and the control Calculating the position of the control point in the parent coordinate system based on the position of the point in the sub-coordinate system with the scale changed;
An image generation apparatus characterized by that.   The image generation device according to any one of claims 1 to 10,
  The storage unit further stores information indicating a scaling rate of the main bone,
  When it is determined that the bounding area and the obstacle object collide, the calculation unit expands / contracts the main bone and changes the sub bone by changing the stored expansion / contraction ratio. Scale using the scaling factor,
  An image generation apparatus characterized by that.   The image generation device according to any one of claims 1 to 10,
  The storage unit further stores information indicating a scaling rate of the main bone,
  The calculation unit expands / contracts the main bone and changes the sub-bone according to the magnitude of the external force acting on the object for which the bounding area is set, Scaling using the scaled rate,
  An image generation apparatus characterized by that. An image generation method executed by an image generation apparatus having a storage unit, a collision determination unit, a calculation unit, an image generation unit, and an update unit,
In the storage unit , the position of the main bone in a coordinate system (hereinafter referred to as “parent coordinate system”) arranged in the virtual space, and a coordinate system fixed to the main bone (hereinafter referred to as “main coordinate system”). And the position of the control point associated with the sub-bone in the coordinate system fixed to the sub-bone (hereinafter referred to as “sub-coordinate system”) and the sub-coordinate system associated with the sub-bone. the position of the bounding area whose position is fixed at a position in the parent coordinate system of the obstacle objects, is stored,
The collision determination unit includes: a position of the main bone in the parent coordinate system; a position of the sub bone in the main coordinate system; a position of the bounding area in the sub coordinate system to which the bounding area is assigned; A collision determination step for determining whether or not the bounding area and the obstacle object collide based on the position of the obstacle object in the parent coordinate system;
The calculation unit determines the parent of the control point based on the position of the main bone in the parent coordinate system, the position of the sub-bone in the main coordinate system, and the position of the control point in the sub-coordinate system. A calculation step for calculating a position in the coordinate system;
The image generation unit determines the shape of the skin according to the calculated position of the control point, and generates an image representing the shape of the skin arranged in the virtual space;
The updating unit updates the position of the secondary bone in the main coordinate system, changes the shape of the skin, and the obstacle object collides with the position of the bounding area determined to collide with the obstacle object. until no, so away from the obstacle objects, and update step you move along with the auxiliary bones,
An image generation method comprising: Computer
The position of the main bone in the coordinate system (hereinafter referred to as “parent coordinate system”) arranged in the virtual space, and the position of the sub bone in the coordinate system fixed to the main bone (hereinafter referred to as “main coordinate system”) The position of the control point associated with the sub-bone in the coordinate system fixed to the sub-bone (hereinafter referred to as “sub-coordinate system”) and the position in the sub-coordinate system associated with the sub-bone are fixed. A storage unit for storing the position of the bounding area and the position of the obstacle object in the parent coordinate system ;
The position of the main bone in the parent coordinate system, the position of the sub bone in the main coordinate system, the position of the bounding area in the sub coordinate system to which the bounding area is assigned, and the obstacle in the parent coordinate system A collision determination unit that determines whether or not the bounding area and the obstacle object collide based on the position of the object object;
Based on the position of the main bone in the parent coordinate system, the position of the sub bone in the main coordinate system, and the position of the control point in the sub coordinate system, the position of the control point in the parent coordinate system is determined. Calculation part to calculate,
An image generation unit that determines the shape of the skin according to the calculated position of the control point and generates an image representing the shape of the skin arranged in the virtual space;
Update the position of the secondary bone in the main coordinate system, change the shape of the skin, and change the position of the bounding area determined to collide with the obstacle object until the obstacle object no longer collides. as away from the obstacle object updater move along with the auxiliary bones,
A program characterized by functioning as

Images