Module org.dyn4j

Package org.dyn4j.dynamics.joint

Class FrictionJoint<T extends PhysicsBody>

Object

Joint<T>

FrictionJoint<T>

Type Parameters:

T - the PhysicsBody type

All Implemented Interfaces:

DataContainer, Shiftable, Ownable

public class FrictionJoint<T extends PhysicsBody>
extends Joint<T>
implements Shiftable, DataContainer

Implementation of a friction joint.

A friction joint is a constraint that drives both linear and angular velocities to zero.

This joint is typically used with one dynamic and one static body. In this context, the joint will apply linear and angular friction to stop the body's motion.

Setting the maximum force and torque values will determine the rate at which the motion is stopped. These values are defaulted to 10 and 0.25 respectively.

NOTE: In versions 3.4.0 and below, the maximum force and torque values were 0 by default. This was changed in 4.0.0 to allow users to better understand the use of this joint when first using it.

Since:

1.0.0

Version:

4.0.0

Author:

William Bittle

See Also:

Documentation

Constructor Summary

Constructors

Constructor	Description
FrictionJoint(T body1, T body2, Vector2 anchor)	Minimal constructor.

Method Summary

Modifier and Type	Method	Description
Vector2	getAnchor1()	Returns the anchor point on the first PhysicsBody in world coordinates.
Vector2	getAnchor2()	Returns the anchor point on the second PhysicsBody in world coordinates.
double	getMaximumForce()	Returns the maximum force this constraint will apply in newtons.
double	getMaximumTorque()	Returns the maximum torque this constraint will apply in newton-meters.
Vector2	getReactionForce(double invdt)	Returns the force applied to the PhysicsBodys in order to satisfy the constraint in newtons.
double	getReactionTorque(double invdt)	Returns the torque applied to the PhysicsBodys in order to satisfy the constraint in newton-meters.
void	initializeConstraints(TimeStep step, Settings settings)	Performs any initialization of the velocity and position constraints.
void	setMaximumForce(double maximumForce)	Sets the maximum force this constraint will apply in newtons.
void	setMaximumTorque(double maximumTorque)	Sets the maximum torque this constraint will apply in newton-meters.
void	shift(Vector2 shift)	Translates the object to match the given coordinate shift.
boolean	solvePositionConstraints(TimeStep step, Settings settings)	Solves the position constraints.
void	solveVelocityConstraints(TimeStep step, Settings settings)	Solves the velocity constraints.
String	toString()

Methods inherited from class Joint

getBody1, getBody2, getOtherBody, getOwner, getUserData, isActive, isCollisionAllowed, isEnabled, isOnIsland, setCollisionAllowed, setOnIsland, setOwner, setUserData

Methods inherited from class Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface DataContainer

getUserData, setUserData

Constructor Detail

FrictionJoint

public FrictionJoint(T body1,
                     T body2,
                     Vector2 anchor)

Minimal constructor.

Parameters:

body1 - the first PhysicsBody

body2 - the second PhysicsBody

anchor - the anchor point in world coordinates

Throws:

NullPointerException - if body1, body2, or anchor is null

IllegalArgumentException - if body1 == body2

Method Detail

toString

public String toString()

Overrides:

toString in class Joint<T extends PhysicsBody>

initializeConstraints

public void initializeConstraints(TimeStep step,
                                  Settings settings)

Description copied from class: Joint

Performs any initialization of the velocity and position constraints.

Specified by:

initializeConstraints in class Joint<T extends PhysicsBody>

Parameters:

step - the time step information

settings - the current world settings

solveVelocityConstraints

public void solveVelocityConstraints(TimeStep step,
                                     Settings settings)

Description copied from class: Joint

Solves the velocity constraints.

Specified by:

solveVelocityConstraints in class Joint<T extends PhysicsBody>

Parameters:

step - the time step information

settings - the current world settings

solvePositionConstraints

public boolean solvePositionConstraints(TimeStep step,
                                        Settings settings)

Description copied from class: Joint

Solves the position constraints.

Specified by:

solvePositionConstraints in class Joint<T extends PhysicsBody>

Parameters:

step - the time step information

settings - the current world settings

Returns:

boolean true if the position constraints were solved

getAnchor1

public Vector2 getAnchor1()

Description copied from class: Joint

Returns the anchor point on the first PhysicsBody in world coordinates.

Specified by:

getAnchor1 in class Joint<T extends PhysicsBody>

Returns:

Vector2

getAnchor2

public Vector2 getAnchor2()

Description copied from class: Joint

Returns the anchor point on the second PhysicsBody in world coordinates.

Specified by:

getAnchor2 in class Joint<T extends PhysicsBody>

Returns:

Vector2

getReactionForce

public Vector2 getReactionForce(double invdt)

Description copied from class: Joint

Returns the force applied to the PhysicsBodys in order to satisfy the constraint in newtons.

Specified by:

getReactionForce in class Joint<T extends PhysicsBody>

Parameters:

invdt - the inverse delta time

Returns:

Vector2

getReactionTorque

public double getReactionTorque(double invdt)

Description copied from class: Joint

Returns the torque applied to the PhysicsBodys in order to satisfy the constraint in newton-meters.

Specified by:

getReactionTorque in class Joint<T extends PhysicsBody>

Parameters:

invdt - the inverse delta time

Returns:

double

shift

public void shift(Vector2 shift)

Description copied from interface: Shiftable

Translates the object to match the given coordinate shift.

Specified by:

shift in interface Shiftable

Parameters:

shift - the amount to shift along the x and y axes

getMaximumTorque

public double getMaximumTorque()

Returns the maximum torque this constraint will apply in newton-meters.

Returns:

double

setMaximumTorque

public void setMaximumTorque(double maximumTorque)

Sets the maximum torque this constraint will apply in newton-meters.

Parameters:

maximumTorque - the maximum torque in newton-meters; in the range [0, ∞]

Throws:

IllegalArgumentException - if maxTorque is less than zero

getMaximumForce

public double getMaximumForce()

Returns the maximum force this constraint will apply in newtons.

Returns:

double

setMaximumForce

public void setMaximumForce(double maximumForce)

Sets the maximum force this constraint will apply in newtons.

Parameters:

maximumForce - the maximum force in newtons; in the range [0, ∞]

Throws:

IllegalArgumentException - if maxForce is less than zero