JPH11283048A - Overlap prevention method of moving object in computer graphics and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for preventing the overlap of moving objects with each other in computer graphics. SOLUTION: In a predicted position calculation part 2, a presence position after unit time is predicted and calculated based on the present moving speed of the object. A collision judgement part 3 judges whether or not it is to collide with the other object at the position, and in the case of colliding, a speed control part 4 evades the excessive cave-in of the objects with each other by calculating an object position immediately before a collision by using a simple geometrical operation and calculating back and correcting the speed so as to reach the position after the unit time further.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to computer graphics, and more particularly to a method and apparatus for preventing overlapping of moving objects in computer graphics, which prevents displayed moving objects from overlapping each other.

[0002]

2. Description of the Related Art In general, in a motion simulation, an object is modeled as a geometric shape that can be mathematically handled, and it is determined whether or not the objects collide with each other in accordance with the motion, that is, the movement in space. That is, this is realized by performing a collision detection, and when a collision is detected, repeating a process of updating the moving speed and the existing position according to the manner and degree of the collision. At this time, if the number of repetitions of the above processing in a unit time is reduced because the shape of the object is complicated or the number of objects to be subjected to collision determination is large, the motion calculation, that is, the speed and the position of the moving object are reduced. There is a problem in that the calculation error in the calculation increases, and when the objects are represented by computer graphics, the objects are displayed as if they were immersed in each other.

Conventionally, a method has been adopted in which the collision determination process, which is one of the procedures having the largest processing amount, is speeded up, the number of repetitions of the process per unit time is increased, and the occurrence of the immersion phenomenon is suppressed.

For example, as disclosed in Japanese Patent Application Laid-Open No. 2-224004 (Title of Invention; "Interference Checking Device for Moving Object"), a simple shape covering an original object, such as using a sphere, is used. Reduce the time required for collision detection by using an object as an alternative object for collision detection, or by hierarchically configuring the corresponding alternative object based on the initial position of the object and the initial relationship between objects. Is being planned.

Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. 7-230559 (title of the invention; "collision determination processing system and image processing apparatus using the same"), a simple original object There is also known a method in which a plurality of substitute objects having different shapes are used to increase the processing speed without lowering the accuracy of collision detection.

FIG. 6 shows the configuration of the above-described conventional collision detection device as shown in FIG. However, FIG.
Are described in JP-A-2-224004 and JP-A-7-224.
It has been newly created by the inventor based on the contents described in Japanese Patent Publication No. 230559/1990. Referring to FIG. 6, the configuration includes an object data storage unit 101 and a collision determination unit 103. The collision determination unit 103 includes an alternative shape generation unit 1031 and a determination unit 1032, and the alternative shape generation unit 1031 includes the object data storage unit 10
One simple shape corresponding to the original shape read from No. 1 or an alternative shape obtained by combining a plurality of simple shapes is generated and passed to the determination unit 1032.

[0007]

However, in the conventional method of speeding up the collision determination processing, even if a substitute object having a simple shape is used, if the number of objects to be subjected to the motion simulation increases, The time required for the processing becomes enormous, and there is a problem that the simulation accuracy is lowered, for example, the phenomenon of overlap (overlap) between the objects frequently occurs, the degree of the penetration is increased, and the like.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above problems, and has as its object to provide a computer graphic capable of preventing objects from overlapping on a screen even when the number of objects is large. An object of the present invention is to provide a method and an apparatus for preventing overlap of a moving object in a vehicle.

[0009]

According to the present invention, there is provided a method of preventing overlapping of a moving object in computer graphics, comprising the steps of: storing an object shape, a position and a speed as object data from an object data storage unit; A predicted position calculating step of reading a speed and calculating a predicted position of the first object after a predetermined time; a shape and a position of the second object read from the object data storage unit; and the first object A collision determination step of determining whether or not the first and second objects collide with each other using the predicted position of the first object and a first object when the collision determination unit determines that there is a collision. Calculating the correction position from the position and shape of the second object and the position and shape of the second object, and reading the speed of the first object from the object data storage unit and the predicted position , Using the correction position, the first
And a speed control step of correcting the speed of the object.

[0010] In the overlap prevention method for a moving object in computer graphics according to the present invention, in the overlap prevention method, the position and shape of the first object and the second object may be determined in the speed control step. A corrected position is calculated from the position and the shape of the first object, and the speed of the first object read from the object data storage unit, the predicted position, the corrected position, and the shape of the first object are used. And correcting the speed of the first object.

According to the present invention, there is provided an apparatus for preventing a moving object from overlapping in computer graphics, comprising: an object data storage unit for storing the shape, position and speed of an object as object data; A predicted position calculation unit that reads from the storage unit and calculates a predicted position of the first object after a predetermined time; a shape and a position of the second object read from the object data storage unit; Using the predicted position of the object, the first
And a collision determination unit that determines whether the second object collides with each other. If the collision determination unit determines that there is a collision, the position and shape of the first object and the position of the second object Calculating a correction position from a position and a shape, and reading the speed of the first object from the object data storage unit;
A speed controller that corrects the speed of the first object using the predicted position and the correction position is provided.

According to the present invention, there is provided an apparatus for preventing a moving object from overlapping in computer graphics according to the present invention, wherein the position and shape of the first object and the position and shape of the second object are corrected. Calculating a position, the speed control unit reads the speed of the first object read from the object data storage unit, the predicted position, the corrected position, the shape of the first object,
Is used to correct the speed of the first object.

A computer-readable recording medium according to the present invention reads out the position and speed of a first object from an object data storage unit that stores the shape, position and speed of the object as object data, and reads the position and speed of the first object after a predetermined time. A predicted position calculation step of calculating a predicted position of the first object; a shape and position of the second object read from the object data storage unit; and a predicted position of the first object, using the first position. And a collision determining step of determining whether or not the second object collides with each other. If the collision determining unit determines that there is a collision, the position and shape of the first object and the position of the second object Calculate the correction position from the position and shape,
Using the computer to execute a speed control step of correcting the speed of the first object using the speed of the first object read from the object data storage unit, the predicted position, and the correction position. Is recorded.

The computer-readable recording medium according to the present invention is the computer-readable recording medium described above, wherein in the speed control step, the position and shape of the first object and the position and shape of the second object are determined. Calculating a correction position from a shape, using the speed of the first object read from the object data storage unit, the predicted position, the correction position, and the shape of the first object, The speed of the first object is corrected.

[0015]

Embodiments of the present invention will be described below. The present invention, as a preferred embodiment thereof, in a collision detection device that detects collision between objects,
A predicted position calculation unit (2 in FIG. 1) for predicting and calculating the position where the moving object reaches after a predetermined time; and a collision determination unit (3 in FIG. 1) for determining whether or not the objects have collided. A speed control unit (4 in FIG. 1) for calculating the speed of the object based on the shape and position of the object colliding with each other, and when the collision determination unit (3 in FIG. 1) determines that there is a collision, It is characterized in that the speed of a moving object is corrected and controlled.

In the motion simulation, if the time interval at which the collision determination process is repeated becomes long, the distance that the objects move within a unit time increases, and excessive intrusion between the objects occurs. However, since the current position and speed of the object are known, the position immediately before the sinking can be obtained by calculation.

In the embodiment of the present invention, the position of the object after a unit time is predicted based on the current moving speed of the object,
When colliding with another object at that position, the object position immediately before the collision is calculated using a simple geometric operation, and the speed is back-calculated and corrected to reach the position after a unit time, so that the objects can be compared with each other. Avoid excessive sinking.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention;

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. Referring to FIG. 1, in the present embodiment, an object data storage unit 1 that stores the shape, position, and speed of an object as object data, and a position and speed of an object that are read from the object data storage unit 1 and are determined in advance. Using the predicted position calculating unit 2 that calculates a predicted position after a time, the shape and position of the object read from the object data storage unit 1, and the predicted position obtained by the predicted position calculating unit 2, And a collision determination unit 3 that determines whether or not the objects collide with each other. If the collision determination unit 3 determines that there is a collision, the shape and position of the object read from the object data storage unit 1 and the The speed control unit 4 is configured to correct the speed of the moving object using the speed of the moving object and the predicted position obtained by the predicted position calculation unit 2.

FIG. 2 is a flow chart for explaining the operation of the entire embodiment shown in FIG. 1 and 2
The operation of the entire embodiment will be described below with reference to FIG.

The object data storage unit 1 previously stores information on the shape of the object, the position of the object in the space, and the moving speed in the space as three-dimensional vector data.

First, the predicted position calculation section 2 starts operation.

The predicted position calculating unit 2 first selects one moving object, that is, an object whose velocity magnitude is not 0, from the object data stored in the object data storage unit 1. Hereinafter, this object is referred to as a first object. Next, the speed data and the position data of the first object are read from the object data storage unit 1. Then, a predicted position after a predetermined time is obtained (step S1). Assuming that the current velocity and position vectors are V and P, respectively, the predicted position vector after time t can be calculated by V · t + P. As the time interval t, a method of using a constant value stored in the storage means provided in the predicted position calculation unit 2 or the time position calculation using the timekeeping means provided in the predicted position calculation unit 2 is performed every time the position is calculated. There is a method of measuring and using the elapsed time from the time of calculation and the like. The use of the collision detection device according to the present invention configured using the latter method makes it possible to realize a more accurate motion simulation.

Subsequently, the collision judging section 3 starts the operation.

The collision determining unit 3 first selects one object other than the first object from the object data stored in the object data storage unit 1. Hereinafter, this object is referred to as a second object. Next, the shape data and position data of the second object and the shape data of the first object are stored in the object data storage unit 1.
Read from. In addition, the predicted position data of the first object obtained earlier is read from the predicted position calculation unit 2. Here, as the shape data, a method of using the shape of the object as it is,
There is a method of assuming and using a simple shape for covering an object. When the former method is used, although it takes time to determine the collision, it is possible to determine the presence or absence of the collision with high accuracy. On the other hand, if the latter method is used, it is possible to determine the presence or absence of a collision in a short time, although the accuracy of the collision determination is low. Examples of simple shapes when the latter method is used include a cube, a rectangular parallelepiped, and a sphere.

Then, it is determined by calculation whether the first object and the second object collide with each other (step S2). This calculation includes, for example, a document (Communications of the ACM)
of the ACM), Vol. 22, No. 1, 1979, J.M.
W. Mr. Boyse's dissertation, "Interference Detection among Solids and Sur
faces) ”).

As a result of the calculation, when the first object and the second object collide with each other, the speed control unit 4 starts operating. The operation ends (step S3).

The speed controller 4 first reads the shape data, position data, and speed data of the first object from the object data storage 1. Further, the shape data and the position data of the second object are read from the object data storage unit 1. Next, using the shape data and position data of the first object and the shape data and position data of the second object,
The position of the first object at the moment when the object collides with the stationary second object is calculated (step S4). Further, the distance that the first object moves until it collides with the second object is calculated. Then, the distance that the first object moves within the time t is D, the distance that the first object moves until it collides with the second object is d, and the speed of the first object before correction is V. When the speed of the first object after the correction is
It is obtained according to a calculation formula of V · d / D and is written in the object data storage unit 1 (step S5). If it is difficult to calculate the position of the first object at the “moment” when the first object collides with the second object, the first object and the second object collide “slightly”. "A little" to each other when displayed in computer graphics
What is necessary is just to calculate the position of the 1st object in the state where it is sinking. Also, if the position is difficult to calculate due to the complex shape of the object, use an alternative object with a simple shape that approximates the object, such as a sphere or a rectangular parallelepiped that encompasses the object. The position may be calculated.

With the above steps, the operation of the entire embodiment is completed.

Next, assuming a specific object shape, FIG.
The operation of the speed control unit 4 in will be described in more detail.

Here, as an example, a scene as shown in FIGS. 3 and 4 is assumed. This is a model of how a moving sphere approaches a stationary polyhedron. In FIGS. 3 and 4, what should be expressed three-dimensionally is shown by a two-dimensional figure for explanation.

It is assumed that the object 1 exists at the position a at a certain time. At this time, the moving speed (speed vector) of the object 1
, It can be predicted that “the object 1 reaches the position b after a unit time”. The moving route at this time is the locus ab. FIG. 3 shows that the moving speed is low,
FIG. 4 shows an example in which the object 1 does not collide with the object 2 after a unit time, and FIG. If it is predicted that a collision will occur after a unit time, the magnitude of the velocity vector is corrected so that the object 1 is controlled so as to reach only the position b ′ and collision with the object 2 is avoided.

For this purpose, first, the surface of the object 2 and the trajectory a
Find intersection 3 with b. Next, the distance from the intersection 3 to the position a of the center of gravity of the object 1 is calculated. This distance is d, object 1
The average distance from the center of gravity of the object 1 to the surface of the object 1 is r, the distance from the position a to the position b is D, and the velocity (before correction) of the object 1 at the position b is V, V · (dr) / D By correcting the speed of the object 1 according to the following equation, it is possible to avoid collision with the object 2 as shown in FIG.

When the shape of the object 1 is a sphere, the average distance r from the center of gravity of the object 1 to the surface of the object 1 matches the radius of the object 1. Therefore, when the shape of the object 1 is complicated, a sphere containing the object 1 is considered, and the sphere is used as a substitute object of the object 1 to reduce the processing amount required for calculating the average distance r. be able to. When the size of the object 1 is sufficiently smaller than the size of the object 2, the average distance r may be regarded as 0.

As described above, in the present embodiment, the presence or absence of collision between objects is detected in advance, and when a collision occurs, the moving speed of the object is corrected and controlled based on the distance to the collision. It is possible to avoid a violent collision, that is, a phenomenon of being greatly sunk when displayed by computer graphics. Note that, for example, the processing procedure of the flowchart illustrated in FIG. 2 can be realized by executing a program on the information processing device.

[0036]

As described above, according to the present invention,
By dynamically controlling the moving speed of the object, a violent collision can be avoided, so that there is an effect that a phenomenon that objects are excessively immersed in display in computer graphics or the like is suppressed.

The above-described effects are important in realizing a high-accuracy simulation using computer graphics.
It is very effective and the practical value of the present invention is extremely high.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the entire embodiment of the present invention.

FIG. 3 is a diagram for explaining an embodiment of the present invention, and is a diagram showing a case where objects do not collide with each other.

FIG. 4 is a diagram for explaining the embodiment of the present invention, and is a diagram showing a case where objects collide with each other.

FIG. 5 is a diagram for explaining the embodiment of the present invention, and is a diagram showing a state in which collision between objects is avoided by speed correction.

FIG. 6 is a block diagram showing a conventional device.

[Explanation of symbols]

 Reference Signs List 1 object data storage unit 2 predicted position calculation unit 3 collision determination unit 4 speed control unit 101 object data storage unit 103 collision determination unit 1031 alternative shape generation unit 1032 determination unit

Claims (6)

[Claims] 1. A position and a speed of a first object are read from an object data storage unit that stores a shape, a position and a speed of the object as object data, and a predicted position of the first object after a predetermined time is calculated. A predicted position calculation step of performing, a shape and a position of the second object read from the object data storage unit, and a predicted position of the first object,
A collision determining step of determining whether or not the first and second objects collide with each other; and if the collision determining unit determines that there is a collision, the position and shape of the first object and the second The corrected position is calculated from the position and shape of the object, and the speed of the first object read from the object data storage unit, the predicted position, and the speed of the first object are calculated using the corrected position. And a speed control step of correcting a moving object. 2. The method for preventing overlap in computer graphics according to claim 1, wherein in the speed control step, a correction position is determined based on a position and a shape of the first object and a position and a shape of the second object. Calculated and read out from the object data storage unit.
Using the speed of the object, the predicted position, the corrected position, and the shape of the first object to correct the speed of the first object. Prevention method. 3. An object data storage unit for storing the shape, position and speed of the object as object data, and reading the position and speed of the first object from the object data storage unit, and reading the first object after a predetermined time. A predicted position calculation unit that calculates the predicted position of the object, using the shape and position of the second object read from the object data storage unit and the predicted position of the first object,
A collision determining unit that determines whether or not the first and second objects collide with each other; and, if the collision determining unit determines that there is a collision, the position and shape of the first object and the second The corrected position is calculated from the position and shape of the object, and the speed of the first object read from the object data storage unit, the predicted position, and the speed of the first object are calculated using the corrected position. And a speed control unit that corrects a moving object in the computer graphics. 4. The apparatus for preventing overlap in computer graphics according to claim 3, wherein the speed control unit determines a correction position based on the position and shape of the first object and the position and shape of the second object. Using the calculated speed of the first object read from the object data storage unit, the predicted position, the corrected position, and the shape of the first object, A device for preventing overlap in computer graphics, wherein the device corrects speed. 5. The position and speed of a first object are read from an object data storage unit that stores the shape, position and speed of the object as object data, and a predicted position of the first object after a predetermined time is calculated. A predicted position calculation step of performing, a shape and a position of the second object read from the object data storage unit, and a predicted position of the first object,
A collision determining step of determining whether or not the first and second objects collide with each other; and if the collision determining unit determines that there is a collision, the position and shape of the first object and the second The corrected position is calculated from the position and shape of the object, and the speed of the first object read from the object data storage unit, the predicted position, and the speed of the first object are calculated using the corrected position. A computer-readable recording medium, which stores a program for causing a computer to execute a speed control step of correcting the following. 6. The computer-readable recording medium according to claim 5, wherein, in the speed control step, a correction position is calculated from a position and a shape of the first object and a position and a shape of the second object. The speed of the first object read from the object data storage unit, the predicted position, the corrected position, the shape of the first object,
A computer-readable recording medium for correcting a speed of the first object by using a computer.