com.jme3.bullet.joints

Class Constraint

java.lang.Object

com.jme3.bullet.NativePhysicsObject

com.jme3.bullet.joints.PhysicsJoint

com.jme3.bullet.joints.Constraint

All Implemented Interfaces:

java.lang.Comparable<NativePhysicsObject>

Direct Known Subclasses:

ConeJoint, GearJoint, HingeJoint, New6Dof, Point2PointJoint, SixDofJoint, SliderJoint

public abstract class Constraint
extends PhysicsJoint

The abstract base class for rigid-body physics joints based on Bullet's btTypedConstraint. A Constraint can be single-ended or double-ended:

• A single-ended Constraint constrains the motion of a dynamic rigid body.
• A double-ended Constraint connects 2 rigid bodies together in the same PhysicsSpace. One or both of the bodies must be dynamic.

Subclasses include: ConeJoint, GearJoint, HingeJoint, New6Dof, Point2PointJoint, SixDofJoint, SixDofSpringJoint, and SliderJoint.

Field Summary

Fields

Modifier and Type	Field and Description
static java.util.logging.Logger	logger15 message logger for this class
protected Vector3f	pivotA copy of the pivot location: in physics-space coordinates if bodyA is null, or else in A's scaled local coordinates
protected Vector3f	pivotB copy of the pivot location: in physics-space coordinates if bodyB is null, or else in B's scaled local coordinates

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

logger

Fields inherited from class com.jme3.bullet.NativePhysicsObject

loggerN

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Constraint(PhysicsBody bodyA, PhysicsBody bodyB, Vector3f pivotInA, Vector3f pivotInB) Instantiate an enabled, double-ended Constraint.
protected	Constraint(PhysicsRigidBody body, JointEnd bodyEnd, Vector3f pivotInBody) Instantiate an enabled, single-ended Constraint using the specified body at the specified end.
protected	Constraint(PhysicsRigidBody body, JointEnd bodyEnd, Vector3f pivotInBody, Vector3f pivotInWorld) Instantiate an enabled, single-ended Constraint using the specified body at the specified end.

Method Summary

Modifier and Type	Method and Description
float	getAppliedImpulse() Determine the magnitude of the applied impulse.
PhysicsRigidBody	getBodyA() Access the rigid body at the A end.
PhysicsRigidBody	getBodyB() Access the rigid body at the B end.
float	getBreakingImpulseThreshold() Determine the breaking impulse threshold.
protected static int	getConstraintType(long constraintId) Read the constraint type.
int	getOverrideIterations() Determine the number of iterations used to solve this Constraint.
Vector3f	getPivot(JointEnd end, Vector3f storeResult) Copy the location of the specified connection point in the specified body.
Vector3f	getPivotA(Vector3f storeResult) Copy the location of the connection point in the body at the A end.
Vector3f	getPivotB(Vector3f storeResult) Copy the location of the connection point in the body at the B end.
boolean	isCollisionBetweenLinkedBodies() Test whether collisions are handled between the ends.
boolean	isEnabled() Test whether this Constraint is enabled.
boolean	isFeedback() Test whether this Constraint has feedback enabled.
void	overrideIterations(int numIterations) Override the number of iterations used to solve this Constraint.
void	setBreakingImpulseThreshold(float desiredThreshold) Alter the breaking impulse threshold.
void	setCollisionBetweenLinkedBodies(boolean allow) Handle/ignore collisions between the ends of a double-ended joint.
void	setEnabled(boolean enable) Enable or disable this Constraint.
void	setFeedback(boolean enable) Enable or disable feedback for this Constraint.
protected void	setPivotInA(Vector3f location) Alter the pivot location in A's scaled local coordinates.
protected void	setPivotInB(Vector3f location) Alter the pivot location in B's scaled local coordinates.

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

countEnds, destroy, findEnd, findOtherBody, getBody, getPhysicsSpace, setBodyA, setBodyB, setNativeId, setPhysicsSpace, toString

Methods inherited from class com.jme3.bullet.NativePhysicsObject

compareTo, countTrackers, dumpTrackers, equals, freeUnusedObjects, hasAssignedNativeObject, hashCode, nativeId, reassignNativeId, setNativeIdNotTracked, unassignNativeObject

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

logger15

public static final java.util.logging.Logger logger15

message logger for this class

pivotA

protected Vector3f pivotA

copy of the pivot location: in physics-space coordinates if bodyA is null, or else in A's scaled local coordinates

pivotB

protected Vector3f pivotB

copy of the pivot location: in physics-space coordinates if bodyB is null, or else in B's scaled local coordinates

Constructor Detail

Constraint

protected Constraint(PhysicsRigidBody body,
                     JointEnd bodyEnd,
                     Vector3f pivotInBody)

Instantiate an enabled, single-ended Constraint using the specified body at the specified end.

To be effective, the Constraint must be added to the body's PhysicsSpace and the body must be dynamic.

Parameters:

body - the body to constrain (not null, alias created)

bodyEnd - at which end to attach the body (not null)

pivotInBody - the pivot location in the body's scaled local coordinates (not null, unaffected)

Constraint

protected Constraint(PhysicsRigidBody body,
                     JointEnd bodyEnd,
                     Vector3f pivotInBody,
                     Vector3f pivotInWorld)

Instantiate an enabled, single-ended Constraint using the specified body at the specified end.

To be effective, the Constraint must be added to the body's PhysicsSpace and the body must be dynamic.

Parameters:

body - the body to constrain (not null, alias created)

bodyEnd - at which end to attach the body (not null)

pivotInBody - the pivot location in the body's scaled local coordinates (not null, unaffected)

pivotInWorld - the pivot location in physics-space coordinates (not null, unaffected)

Constraint

protected Constraint(PhysicsBody bodyA,
                     PhysicsBody bodyB,
                     Vector3f pivotInA,
                     Vector3f pivotInB)

Instantiate an enabled, double-ended Constraint.

To be effective, the Constraint must be added to the PhysicsSpace of both bodies. Also, the bodies must be distinct and at least one of them must be dynamic.

Parameters:

bodyA - the body for the A end (not null, alias created)

bodyB - the body for the B end (not null, alias created)

pivotInA - the pivot location in A's scaled local coordinates (not null, unaffected)

pivotInB - the pivot location in B's scaled local coordinates (not null, unaffected)

Method Detail

getAppliedImpulse

public float getAppliedImpulse()

Determine the magnitude of the applied impulse. Requires feedback.

Returns:

impulse magnitude (≥0)

Throws:

java.lang.IllegalStateException - if feedback is not enabled

getBreakingImpulseThreshold

public float getBreakingImpulseThreshold()

Determine the breaking impulse threshold.

Returns:

the threshold value

getOverrideIterations

public int getOverrideIterations()

Determine the number of iterations used to solve this Constraint.

Returns:

the number of iterations (≥0) or -1 if using the solver's default

getPivot

public Vector3f getPivot(JointEnd end,
                         Vector3f storeResult)

Copy the location of the specified connection point in the specified body.

Parameters:

end - which end of the Constraint to access (not null)

storeResult - storage for the result (modified if not null)

Returns:

a location vector (in scaled local coordinates, either storeResult or a new instance)

getPivotA

public Vector3f getPivotA(Vector3f storeResult)

Copy the location of the connection point in the body at the A end.

Parameters:

storeResult - storage for the result (modified if not null)

Returns:

a location vector (in A's scaled local coordinates, either storeResult or a new instance)

getPivotB

public Vector3f getPivotB(Vector3f storeResult)

Copy the location of the connection point in the body at the B end.

Parameters:

storeResult - storage for the result (modified if not null)

Returns:

a location vector (in B's scaled local coordinates, either storeResult or a new instance)

isCollisionBetweenLinkedBodies

public boolean isCollisionBetweenLinkedBodies()

Test whether collisions are handled between the ends.

Returns:

true if collisions are handled, otherwise false

isFeedback

public boolean isFeedback()

Test whether this Constraint has feedback enabled.

Returns:

true if enabled, otherwise false

overrideIterations

public void overrideIterations(int numIterations)

Override the number of iterations used to solve this Constraint.

Parameters:

numIterations - the desired number of iterations (≥0) or -1 to use the solver's default (default=-1)

setBreakingImpulseThreshold

public void setBreakingImpulseThreshold(float desiredThreshold)

Alter the breaking impulse threshold.

Parameters:

desiredThreshold - the desired value (default=MAX_VALUE with SP library or +Infinity with DP library)

setCollisionBetweenLinkedBodies

public void setCollisionBetweenLinkedBodies(boolean allow)

Handle/ignore collisions between the ends of a double-ended joint.

Parameters:

allow - true to handle collisions, false to ignore them (default=true)

setEnabled

public void setEnabled(boolean enable)

Enable or disable this Constraint.

Parameters:

enable - true to enable, false to disable (default=true)

setFeedback

public void setFeedback(boolean enable)

Enable or disable feedback for this Constraint.

Parameters:

enable - true to enable, false to disable (default=false)

getConstraintType

protected static final int getConstraintType(long constraintId)

Read the constraint type.

Parameters:

constraintId - identifier of the btTypedConstraint (not zero)

Returns:

a btTypedConstraintType ordinal value (≥3)

setPivotInA

protected void setPivotInA(Vector3f location)

Alter the pivot location in A's scaled local coordinates. The subclass is responsible for updating the native object.

Parameters:

location - the desired location (not null, unaffected)

setPivotInB

protected void setPivotInB(Vector3f location)

Alter the pivot location in B's scaled local coordinates. The subclass is responsible for updating the native object.

Parameters:

location - the desired location (not null, unaffected)

getBodyA

public PhysicsRigidBody getBodyA()

Access the rigid body at the A end.

Overrides:

getBodyA in class PhysicsJoint

Returns:

the pre-existing rigid body, or null if none

getBodyB

public PhysicsRigidBody getBodyB()

Access the rigid body at the B end.

Overrides:

getBodyB in class PhysicsJoint

Returns:

the pre-existing body, or null if none

isEnabled

public boolean isEnabled()

Test whether this Constraint is enabled.

Specified by:

isEnabled in class PhysicsJoint

Returns:

true if enabled, otherwise false