com.jme3.bullet.joints

Class HingeJoint

java.lang.Object

com.jme3.bullet.joints.PhysicsJoint

com.jme3.bullet.joints.HingeJoint

All Implemented Interfaces:

Savable

public class HingeJoint
extends PhysicsJoint

A joint based on Bullet's btHingeConstraint.

From the Bullet manual:
Hinge constraint, or revolute joint restricts two additional angular degrees of freedom, so the body can only rotate around one axis, the hinge axis. This can be useful to represent doors or wheels rotating around one axis. The user can specify limits and motor for the hinge.

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	angularOnly copy of the angular-only flag (default=false)
protected Vector3f	axisA
protected Vector3f	axisB
protected float	biasFactor copy of the limit's bias factor, how strictly position errors (drift) is corrected (default=0.3)
protected float	limitSoftness copy of the limit's softness, the range fraction at which velocity-error correction starts operating (default=0.9)
protected float	relaxationFactor copy of the limit's relaxation factor, the rate at which velocity errors are corrected (default=1)

Fields inherited from class com.jme3.bullet.joints.PhysicsJoint

collisionBetweenLinkedBodys, nodeA, nodeB, objectId, pivotA, pivotB

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	HingeJoint() No-argument constructor needed by SavableClassUtil.
	HingeJoint(PhysicsRigidBody nodeA, PhysicsRigidBody nodeB, Vector3f pivotA, Vector3f pivotB, Vector3f axisA, Vector3f axisB) Instantiate a HingeJoint.

Method Summary

Modifier and Type	Method and Description
protected void	createJoint() Create the configured joint in Bullet.
void	enableMotor(boolean enable, float targetVelocity, float maxMotorImpulse) Enable or disable this joint's motor.
boolean	getEnableMotor() Test whether this joint's motor is enabled.
float	getHingeAngle() Read the hinge angle.
float	getLowerLimit() Read the lower limit of the hinge angle.
float	getMaxMotorImpulse() Read the motor's maximum impulse.
float	getMotorTargetVelocity() Read the motor's target velocity.
float	getUpperLimit() Read the upper limit of the hinge angle.
void	read(JmeImporter im) De-serialize this joint, for example when loading from a J3O file.
void	setAngularOnly(boolean angularOnly) Alter the hinge translation flag.
void	setLimit(float low, float high) Alter this joint's limits.
void	setLimit(float low, float high, float _softness, float _biasFactor, float _relaxationFactor) Alter this joint's limits.
void	write(JmeExporter ex) Serialize this joint, for example when saving to a J3O file.

Methods inherited from class com.jme3.bullet.joints.PhysicsJoint

destroy, finalize, getAppliedImpulse, getBodyA, getBodyB, getObjectId, getPivotA, getPivotB, isCollisionBetweenLinkedBodys, setCollisionBetweenLinkedBodys

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

axisA

protected Vector3f axisA

axisB

protected Vector3f axisB

angularOnly

protected boolean angularOnly

copy of the angular-only flag (default=false)

biasFactor

protected float biasFactor

copy of the limit's bias factor, how strictly position errors (drift) is corrected (default=0.3)

relaxationFactor

protected float relaxationFactor

copy of the limit's relaxation factor, the rate at which velocity errors are corrected (default=1)

limitSoftness

protected float limitSoftness

copy of the limit's softness, the range fraction at which velocity-error correction starts operating (default=0.9)

Constructor Detail

HingeJoint

protected HingeJoint()

No-argument constructor needed by SavableClassUtil. Do not invoke directly!

HingeJoint

public HingeJoint(PhysicsRigidBody nodeA,
                  PhysicsRigidBody nodeB,
                  Vector3f pivotA,
                  Vector3f pivotB,
                  Vector3f axisA,
                  Vector3f axisB)

Instantiate a HingeJoint. To be effective, the joint must be added to a physics space.

Parameters:

nodeA - the 1st body connected by the joint (not null, alias created)

nodeB - the 2nd body connected by the joint (not null, alias created)

pivotA - the local offset of the connection point in node A (not null, alias created)

pivotB - the local offset of the connection point in node B (not null, alias created)

axisA - the local axis of the connection to node A (not null, alias created)

axisB - the local axis of the connection to node B (not null, alias created)

Method Detail

enableMotor

public void enableMotor(boolean enable,
                        float targetVelocity,
                        float maxMotorImpulse)

Enable or disable this joint's motor.

Parameters:

enable - true to enable, false to disable

targetVelocity - the desired target velocity

maxMotorImpulse - the desired maximum rotational force

getEnableMotor

public boolean getEnableMotor()

Test whether this joint's motor is enabled.

Returns:

true if enabled, otherwise false

getMotorTargetVelocity

public float getMotorTargetVelocity()

Read the motor's target velocity.

Returns:

velocity

getMaxMotorImpulse

public float getMaxMotorImpulse()

Read the motor's maximum impulse.

Returns:

impulse

setLimit

public void setLimit(float low,
                     float high)

Alter this joint's limits.

Parameters:

low - the desired lower limit of the hinge angle (in radians)

high - the desired upper limit of the joint angle (in radians)

setLimit

public void setLimit(float low,
                     float high,
                     float _softness,
                     float _biasFactor,
                     float _relaxationFactor)

Alter this joint's limits. If you're above the softness, velocities that would shoot through the actual limit are slowed down. The bias should be in the range of 0.2 - 0.5.

Parameters:

low - the desired lower limit of the hinge angle (in radians)

high - the desired upper limit of the joint angle (in radians)

_softness - the desired range fraction at which velocity-error correction starts operating. A softness of 0.9 means that the correction starts at 90% of the limit range. (default=0.9)

_biasFactor - the desired magnitude of the position correction, how strictly position errors (drift) is corrected. (default=0.3)

_relaxationFactor - the desired rate at which velocity errors are corrected. This can be seen as the strength of the limits. A low value will make the limits more spongy. (default=1)

getUpperLimit

public float getUpperLimit()

Read the upper limit of the hinge angle.

Returns:

angle (in radians)

getLowerLimit

public float getLowerLimit()

Read the lower limit of the hinge angle.

Returns:

the angle (in radians)

setAngularOnly

public void setAngularOnly(boolean angularOnly)

Alter the hinge translation flag.

Parameters:

angularOnly - true→rotate only, false→rotate and translate (default=false)

getHingeAngle

public float getHingeAngle()

Read the hinge angle.

Returns:

the angle (in radians)

write

public void write(JmeExporter ex)
           throws java.io.IOException

Serialize this joint, for example when saving to a J3O file.

Specified by:

write in interface Savable

Overrides:

write in class PhysicsJoint

Parameters:

ex - exporter (not null)

Throws:

java.io.IOException - from exporter

read

public void read(JmeImporter im)
          throws java.io.IOException

De-serialize this joint, for example when loading from a J3O file.

Specified by:

read in interface Savable

Overrides:

read in class PhysicsJoint

Parameters:

im - importer (not null)

Throws:

java.io.IOException - from importer

createJoint

protected void createJoint()

Create the configured joint in Bullet.