JP5787514B2 - Three-dimensional spatial data processing apparatus and program - Google Patents

Description

  The present invention relates to a technique for processing a three-dimensional space that is virtually represented by using a plurality of polygons having a planar polygonal shape, and in particular, determines an intersection between a line segment in a three-dimensional space and a polygon. Regarding technology.

In recent years, a 3D game in which a three-dimensional virtual game space is expressed using a plurality of polygons having a planar polygon shape and a game is developed in the game space has been realized.
In such a 3D game, for example, a collision between an object moving in the game space and another object existing in the game space is determined, and when these collisions are detected, a predetermined image, sound, or the like is output. To inform the game player that a collision between objects has occurred. In such a collision determination, for example, an intersection determination is performed to determine whether a line segment connecting a movement source (start point) and a movement destination (end point) of a moving object passes through a polygon surface forming another object. The presence / absence of a polygon that intersects the line segment is checked, and if a corresponding polygon exists, it is determined that a collision has occurred.

Further, in 3D games, for example, a device for preparing an autonomous character that acts autonomously in a game space to increase the game's preference is also performed. As a technique for route search related to the movement of such an autonomous character, a technique called a navigation mesh (Navigation Meshes) is known.
In the navigation mesh, for example, route data used when a character moves in a game scene (such as a map) is prepared separately from polygons for representing a background, an object, and the like. This route data is a “road” constructed on a triangle basis, and includes information on adjacent triangles to each triangle, and searches for routes on which the character can move using this route data. .
For details of the navigation mesh, for example, “3.6 Simplification of 3D movement and path discovery by navigation mesh” in “Section 3 Artificial Intelligence” in Non-Patent Document 1, “Section 3 Artificial Intelligence” in Non-Patent Document 2 “ 3.7 High-Speed Navigation Mesh ”,“ Section 3 Artificial Intelligence ”of Non-Patent Document 3,“ 3.1 Automatic Retrieval Location Search Using Navigation Mesh ”, and the like.

Mark DeLoura et al., “Game Programming Gems Japanese Version”, Bone Digital, Inc., June 25, 2001 Dante Tregria et al., “Game Programming Gems 3 Japanese Version”, Bone Digital, Inc., December 21, 2004 Kim Pallister et al., “Game Programming Gems 5 Japanese Version”, Born Digital, Inc., September 15, 2006

  Here, for example, in a 3D game that requires immediate responsiveness (real-time performance), such as an action game in which a self character behaves in response to an operation input by a player, a delay (time lag) is required due to processing such as intersection determination. When it occurs, the interest as a game may be impaired, and therefore it is required to reduce the processing load and increase the immediate response.

  The present invention has been made in view of the above-described conventional circumstances, and for a three-dimensional space expressed using a plurality of polygons having a planar polygonal shape, line segments and polygons on the three-dimensional space, The purpose of this technology is to reduce the processing load related to the intersection determination.

  In order to achieve the above object, in the present invention, for a three-dimensional space expressed using a plurality of polygons having a planar polygonal shape, a three-dimensional determination of the intersection of a line segment in the three-dimensional space and the polygon is performed. In the spatial data processing device, the selecting means projects line segments and polygons in a three-dimensional space onto a two-dimensional plane, selects polygons whose sides intersect with the line segments on the two-dimensional plane, and specifying means Then, for the polygon selected by the selection means, a polygon whose surface intersects the line segment in the three-dimensional space is specified.

That is, in the three-dimensional spatial data processing apparatus according to the present invention, instead of determining whether or not the polygon plane intersects with a line segment for all polygons existing in the three-dimensional space, 3 Executes in 3D space by selecting polygons on a 2D plane with less processing burden compared to 3D space, and performing intersection determination on 3D space for polygons narrowed down by the selection The number of intersection judgments is reduced.
As described above, in the present invention, the overall load of the process related to the intersection determination is reduced by effectively narrowing down the polygons to be subjected to the intersection determination in the three-dimensional space on the two-dimensional plane.

  As one configuration example, for a line segment with a start point and an end point, the selection unit intersects the line segment with respect to each side of a polygon having the start point of the line segment in a two-dimensional plane, and Performing the process of determining whether or not the condition that the end point of the line segment is on the outside is satisfied with respect to the side, and performing the process for each side of other polygons sharing the side that satisfies the condition. It may be configured to repeat the process until a polygon that does not have a side satisfying the condition is detected, and to select the polygon that is the object of the process.

According to such a configuration, the determination of the intersection between the line segment and each side of the polygon can be performed by performing processing in one direction from the start point to the end point of the line segment only once. Can be performed efficiently.
In the configuration example described above, if the selection unit is configured to identify other polygons sharing the side satisfying the condition using link data in which polygons sharing the side are associated with each other, the side is determined. It is possible to easily specify other polygons to be shared.

  In addition, the present invention can be realized not as a three-dimensional spatial data processing apparatus as described above, but also as a program for realizing the apparatus by a computer (or a storage medium storing the program in a computer-readable manner). It can also be grasped as a method implemented by the device or program.

  According to the present invention, all polygons existing in the three-dimensional space are targeted, and instead of determining whether the surface of the polygon intersects with the line segment, the processing load is larger than that in the three-dimensional space. Since polygons are selected on a small number of two-dimensional planes, and intersection determination is performed on the three-dimensional space for the polygons narrowed down by the selection, the number of intersection determinations performed on the three-dimensional space is reduced. In other words, since the polygons to be subjected to the intersection determination in the three-dimensional space are effectively narrowed down on the two-dimensional plane, the overall load of the processing relating to the intersection determination is reduced.

It is a figure which illustrates the hardware constitutions of the game device which concerns on one Embodiment of this invention. It is a figure which illustrates the functional block of the game device which concerns on one Embodiment of this invention. It is a figure explaining the collision determination by the game device which concerns on one Embodiment of this invention. It is a figure explaining the collision determination by the game device which concerns on one Embodiment of this invention. It is a figure explaining the collision determination by the game device which concerns on one Embodiment of this invention. It is a figure which illustrates the processing flow of candidate selection processing with the game device which concerns on one Embodiment of this invention. It is a figure explaining candidate selection processing by the game device concerning one embodiment of the present invention. It is a figure which illustrates polygon data in the game device concerning one embodiment of the present invention.

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 illustrates a hardware configuration of a game device that operates as a three-dimensional spatial data processing device according to an embodiment of the present invention.
The game apparatus of this example includes a CPU (Central Processing Unit) 11 that performs various arithmetic processes, a RAM (Random Access Memory) 12 that is a work area of the CPU 11, a ROM (Read Only Memory) 13 that records a basic control program, A communication unit 14 that communicates with other devices by wire or wireless, an operation reception unit 15 that receives an operation input from a player by a key button or the like, an image output unit 16 that outputs a game image on a display (display device), and a game sound It has hardware resources such as an audio output unit 17 that outputs from a speaker (audio device) and an external medium access unit 18 that accesses an external medium loaded in the apparatus.

  When the game apparatus of this example is activated with an external medium storing a game program loaded in the apparatus, the external medium access unit 18 reads out the game program from the external medium and develops it in the RAM 12, which is loaded by the CPU 11. The game program is executed by performing arithmetic processing. That is, the game apparatus of this example operates as a three-dimensional spatial data processing apparatus according to an embodiment of the present invention by using an external medium that stores a game program according to the embodiment of the present invention.

As an external medium, for example, various storage media such as a DVD (Digital Versatile Disc) -ROM, a CD (Compact Disc) -ROM, and a memory cartridge can be used, and an access mechanism of a format corresponding to the storage medium can be used. The external medium access unit 18 may be provided.
In addition, the game program is not read from the external medium by the external medium access unit 18. For example, the game program is received from the external server device by the communication unit 14, and is expanded in the RAM 12 and is processed by the CPU 11. May be.
In addition, the game device of this example is a portable game device that is integrally provided with the above hardware resources. For example, a game image or sound is displayed by a display or a speaker provided separately from the device body. It may be a stationary game device that outputs.

  As an example, the game device of this example includes a self-character and a computer that act in response to a player's operation input in a three-dimensional virtual game space expressed using a plurality of polygons having a planar polygon shape. This game provides a game in which an enemy character that acts autonomously under the control of the game, and determines whether a collision between a character object such as a self-character or an enemy character and a background object such as a terrain or a structure in the game space When a collision between these objects is detected, a predetermined image or sound is output to notify the player that the collision has occurred.

In the game apparatus of this example, such collision detection of objects in the three-dimensional game space is realized by a functional unit as illustrated in FIG.
That is, the game device of this example includes a collision detection unit 21 that detects a collision between a character object and a background object, and a polygon data storage unit 24 that stores data of polygons that form these objects.
The collision detection unit 21 also includes a candidate selection unit 22 that performs a candidate selection process for selecting a candidate polygon that the character object collides from among a plurality of polygons forming the background object, and the candidate selected by the candidate selection unit 22. An intersection determining unit 23 that performs an intersection determination process for determining an intersection with a moving line segment that indicates a path of the character object to be moved, and identifies a polygon that the character object collides with. Yes.

The candidate selection process by the candidate selection unit 22 and the intersection determination process by the intersection determination unit 23 will be described with reference to FIGS.
FIG. 3 shows a situation where a character object is moving from position T to position T ′ in a three-dimensional game space having a background object formed using a triangular polygon. Further, the movement of the character object is expressed by a moving line segment L which is a directed line segment (vector) having the moving source (starting point) as the position T and the moving destination (end point) as the position T ′.

  Here, each vertex of the triangle forming the polygon of the background object and each point of the start point (position T) and end point (position T ′) of the moving line segment L of the character object are represented by three-dimensional coordinate values (x, y, z). The x coordinate is a coordinate in the width direction (X-axis direction) in the three-dimensional space, the y coordinate is a coordinate in the height direction (Y-axis direction) in the three-dimensional space, and the z coordinate is a three-dimensional space. Are coordinates in the depth direction (Z-axis direction). The direction of each axis is determined based on a predetermined viewpoint direction.

In the candidate selection process of the candidate selection unit 22, the intersection determination unit 23 performs the intersection based on the movement line segment data indicating the movement path of the character object and the polygon data of the background object stored in the polygon data storage unit 24. A polygon (candidate polygon with which a character object collides) is selected as a target of determination processing.
Specifically, the candidate selection unit 22 projects the polygons of the background object and the character object in a three-dimensional space onto a two-dimensional plane, and the sides of the polygon on the two-dimensional plane are the movement lines of the character object. Are searched for, and the corresponding polygon is selected as a candidate polygon with which the character object collides, and is supplied to the intersection determination unit 23. For example, when searching for candidate polygons in the XZ plane, two-dimensional of the three-dimensional coordinate values (x, y, z) indicating each point (each vertex of the polygon and each end point of the moving line segment) As a result of projection onto the XZ plane can be obtained by using the coordinate values (x, z), the intersection of the polygon side and the moving line segment can be determined using the two-dimensional coordinate values (x, z). Good.

  FIG. 4 illustrates the result of searching for polygons in the XZ plane. In FIG. 4, diagonal hatch patterns are given to polygons having sides intersecting with the moving line segment L in the XZ plane, and 12 polygons among a large number of polygons forming the background object are selected. The selected polygon is a polygon that may cross the moving line segment L in the three-dimensional space, and is a target of intersection determination processing by the intersection determination unit 23.

  In the intersection determination process of the intersection determination unit 23, for the polygon selected by the candidate selection unit 22, it is determined whether the surface of the polygon intersects the moving line segment of the character object in the three-dimensional space. Specifies a polygon (polygon with which the character object collides) whose surface intersects the moving line of the character object. The intersection between the polygonal surface and the line segment in the three-dimensional space can be determined using various known techniques, and a detailed description thereof will be omitted.

  In the example of FIG. 5, two polygons are specified as polygons that intersect the moving line segment L. In addition, the intersection determination between the selected polygonal surface and the moving line segment L is executed in the order of the polygons along the direction from the starting point (position T) to the ending point (position T ′) of the moving line segment L. The process may be terminated when a polygon whose surface intersects the movement line segment L is found. In this case, only the polygon with which the character object collides first (polygon located on the start point (position T) side of the moving line segment L) is specified.

FIG. 6 illustrates a processing flow of candidate selection processing by the candidate selection unit 22.
In the candidate selection process, for each side of the polygon having the starting point of the moving line segment inside in a two-dimensional plane (for example, the XZ plane), the moving line segment intersects with the moving line segment and the end point of the moving line segment is outside the corresponding side. It is determined whether or not the condition that the condition is present is satisfied (step S11).
In step S11, if a side that satisfies the condition is not found, the process ends. If a side that satisfies the condition is found, another polygon that shares the side is searched (step S12).
If no other polygon is found in step S12, the process is terminated. If another polygon is found, the process returns to step S11, and the above process (steps S11, S12) is performed for the other polygon. This is repeated until a polygon that does not have an edge that satisfies the above conditions is detected.
Then, each polygon subjected to these processes is selected as an object of intersection determination processing by the intersection determination unit 23.

The candidate selection process will be described with reference to a specific example illustrated in FIG.
FIG. 7 shows a state in which a polygon a, a polygon b, a polygon c, and a moving line segment AB are projected onto a two-dimensional plane . Moving segment AB has an end point B on the inside of and polygons c has an internal start point A of the polygon a on a two-dimensional plane. Polygon a has vertex 0, vertex 1 and vertex 2, polygon b has vertex 0, vertex 2 and vertex 3, and polygon c has vertex 2, vertex 4 and vertex 3 have.

In this example, for the above polygon, data as illustrated in FIG. 8 is stored in the polygon data storage unit 24.
FIG. 8A illustrates the vertex data, and holds the coordinate values of the points on the three-dimensional space that are the vertices of the polygon.
FIG. 8B illustrates polygon data, and holds information for specifying each vertex of the polygon and the arrangement order thereof for each polygon. In this example, the direction (front and back) of the polygon surface is determined by the arrangement of the vertices of the polygon. That is, when the polygonal outline is drawn by connecting the vertices along the arrangement order, if it is a counterclockwise outline, it will be the front surface (the outer surface side of the background object), and if it is a clockwise outline, the back surface ( The inner side of the background object). For example, the outline of the polygon a is expressed by an outer side connecting vertex 0 → vertex 1, an outer side connecting vertex 1 → vertex 2, and an outer side connecting vertex 2 → vertex 0. If the connected contour line is counterclockwise, it is determined as the surface.

  FIG. 8C illustrates link data. For each vertex that is the end point of the outer side (line connecting two vertices) that forms the outline of the polygon, the vertex that is the starting point of the outer side that reaches the end point And information specifying a set of polygons having the outer side. By using such link data, it is possible to easily specify other polygons sharing the outer side of a certain polygon. That is, for example, among the outer sides of the polygon a, other polygons sharing the outer side connecting the vertex 2 → vertex 0 (the outer side having the start point as the vertex 2 and the end point as the vertex 0) are the vertex 0 → vertex It can be specified by referring to the link data that the polygon b has the outer side connecting 2 (the outer side having the start point as vertex 0 and the end point as vertex 2).

In the candidate selection process, first, for each outer side of the polygon a having the starting point A of the moving line segment AB inside, the moving line segment AB intersects the moving line segment AB and the end point B of the moving line segment AB is outside the outer side. It is determined whether or not a certain condition is satisfied. As a result, the outer side connecting vertex 2 → vertex 0 is specified.
Next, referring to the link data, a polygon having an outer side opposite to the outer side connecting vertex 2 → vertex 0 is searched. As a result, the polygon b having the outer side connecting the vertex 0 to the vertex 2 is specified.
Next, for each outer side of the polygon b, it is determined whether or not the condition that the moving line segment AB intersects with the moving line segment AB and the end point B of the moving line segment AB is outside the outer side is satisfied. As a result, the outer side connecting vertex 2 → vertex 3 is specified.
Next, referring to the link data, a polygon having an outer side opposite to the outer side connecting vertex 2 → vertex 3 is searched. As a result, a polygon c having an outer side connecting vertex 3 → vertex 2 is specified.
Next, for each outer side of the polygon b, it is determined whether or not the condition that the moving line segment AB intersects with the moving line segment AB and the end point B of the moving line segment AB is outside the outer side is satisfied. As a result, there is no edge that satisfies the condition, and the search is terminated.
Then, the polygons a, b, and c that are the objects of the above processing are selected as the objects of the intersection determination process by the intersection determination unit 23.

  Note that whether or not the end point of the moving line segment is outside the certain outer side can be determined by the outer product of the moving line segment and the outer side. In this example, when the polygon outline (each outer edge) is face-up counterclockwise, when the outer product of the moving line segment vector and the outer vector is calculated, the sign of the outer product is positive. It is determined that the end point of the moving line segment is inside, and if the sign of the outer product is negative, it is determined that the end point of the moving line segment is outside.

  In this example, after a series of candidate selection processes by the candidate selection unit 22 is completed, the intersection determination process by the intersection determination unit 23 is performed on a plurality of polygons selected in this order in order. Each time the candidate selection unit 22 selects a polygon, the intersection determination process by the intersection determination unit 23 may be performed on the selected polygon.

As described above, in the game device of this example, the candidate selection unit 22 projects the polygon of the background object and the moving line of the character object on the two-dimensional plane in the three-dimensional space, and the polygon side on the two-dimensional plane. Selects a polygon that intersects the moving line segment of the character object and supplies the polygon to the intersection determination unit 23, and the intersection determination unit 23 targets the polygon selected by the candidate selection unit 22 as a polygon in a three-dimensional space. It is determined whether or not the plane intersects with the moving line segment of the character object, and a polygon (polygon with which the character object collides) whose polygon plane intersects with the moving line segment of the character object is specified.
Thus, in the game device of this example, the processing load related to the collision determination is reduced by effectively narrowing down the polygons to be subjected to the intersection determination on the three-dimensional space on the two-dimensional plane.

In the above description, a triangular polygon is used. However, other polygons such as a hexagonal polygon may be used.
Further, the present invention may be applied in addition to the collision determination between the character object and the background object. For example, the present invention may be applied to the collision determination between character objects. Further, for example, when specifying the background object ahead of the line of sight of the character object, it may be applied to the intersection determination between the line segment indicating the direction of the line of sight and the polygon of the background object.
The present invention can also be applied to a three-dimensional space data processing device other than a game device, for example, collision determination in a device for performing training of an aircraft, a racing car, etc. in a virtual three-dimensional space. You may apply to.

11: CPU, 12: RAM, 13: ROM, 14: Communication unit, 15: Operation receiving unit, 16: Image output unit, 17: Audio output unit, 18: External medium access unit,
21: Collision detection unit, 22: Candidate selection unit, 23: Intersection determination unit, 24: Polygon data storage unit

Claims (3)

In a three-dimensional space data processing apparatus for determining the intersection of a line segment in a three-dimensional space and a polygon for a three-dimensional space expressed using a plurality of polygons having a planar polygon shape,
Selecting means for projecting line segments and polygons in a three-dimensional space onto a two-dimensional plane, and selecting polygons having sides intersecting the line segments on the two-dimensional plane;
Determination means for determining whether or not a surface of the polygon intersects the line segment in a three-dimensional space for the polygon selected by the selection means;
With
The line segment has a starting point and an ending point in a three-dimensional space,
In the two-dimensional plane on which the line segment and the polygon are projected, the selection means intersects the line segment with respect to each side of the polygon having the start point of the line segment on the two-dimensional plane. Processing to determine whether the condition that the end point of the line segment is outside is satisfied, and performing the processing for each side of other polygons sharing the edge that satisfies the condition, Repeat until a polygon that does not have is detected, and select the polygon to be processed as a determination target by the determination means.
A three-dimensional spatial data processing device. The three-dimensional spatial data processing device includes storage means for storing link data indicating a relationship between polygons sharing sides in a three-dimensional space,
The selection unit specifies, when there is a side satisfying the condition in the two-dimensional plane, as another polygon that shares the side, as another polygon associated by the link data for the side.
The three-dimensional spatial data processing device according to claim 1. A computer that executes a process of determining the intersection between a line segment in a three-dimensional space and a polygon for a three-dimensional space expressed using a plurality of polygons having a planar polygonal shape,
A selection function for projecting line segments and polygons in a three-dimensional space onto a two-dimensional plane, and selecting polygons having sides intersecting the line segments on the two-dimensional plane;
A determination function for determining whether or not a polygon plane intersects the line segment in a three-dimensional space for the polygon selected by the selection function ;
Is a program for realizing
The line segment has a starting point and an ending point in a three-dimensional space,
In the two-dimensional plane on which the line segment and the polygon are projected, the selection function intersects the line segment with respect to each side of the polygon having the start point of the line segment on the two-dimensional plane. Processing to determine whether the condition that the end point of the line segment is outside is satisfied, and performing the processing for each side of other polygons sharing the edge that satisfies the condition, Repeat until a polygon that does not have is detected, and select the polygon to be processed as a determination target by the determination function .
A program characterized by that.

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