Module org.dyn4j

Package org.dyn4j.dynamics.joint

Class WeldJoint<T extends PhysicsBody>

Object

Joint<T>

WeldJoint<T>

Type Parameters:

T - the PhysicsBody type

All Implemented Interfaces:

DataContainer, Shiftable, Ownable

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

Implementation of a weld joint.

A weld joint joins two bodies together as if they were a single body with two fixtures. Both their relative linear and angular motion are constrained to keep them attached to each other. The system as a whole can rotate and translate freely.

Using a frequency greater than zero allows the joint to function as a torsion spring about the anchor point. A good starting point is a frequency of 8.0 and damping ratio of 0.3 then adjust as necessary.

Since:

1.0.0

Version:

4.0.0

Author:

William Bittle

See Also:

Documentation, Weld Constraint

Constructor Summary

Constructors

Constructor	Description
WeldJoint(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	getDampingRatio()	Returns the damping ratio.
double	getFrequency()	Returns the spring frequency.
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.
double	getReferenceAngle()	Returns the reference angle.
void	initializeConstraints(TimeStep step, Settings settings)	Performs any initialization of the velocity and position constraints.
boolean	isSpring()	Deprecated. Deprecated in 4.0.0.
boolean	isSpringDamper()	Deprecated. Deprecated in 4.0.0.
boolean	isSpringDamperEnabled()	Returns true if this distance joint is a spring distance joint with damping.
boolean	isSpringEnabled()	Returns true if this distance joint is a spring distance joint.
void	setDampingRatio(double dampingRatio)	Sets the damping ratio.
void	setFrequency(double frequency)	Sets the spring frequency.
void	setReferenceAngle(double angle)	Sets the reference angle.
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

WeldJoint

public WeldJoint(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

isSpring

@Deprecated
public boolean isSpring()

Deprecated.

Deprecated in 4.0.0. Use the isSpringEnabled() method instead.

Returns true if this distance joint is a spring distance joint.

Returns:

boolean

Since:

3.0.1

isSpringDamper

@Deprecated
public boolean isSpringDamper()

Deprecated.

Deprecated in 4.0.0. Use the isSpringDamperEnabled() method instead.

Returns true if this distance joint is a spring distance joint with damping.

Returns:

boolean

Since:

3.0.1

isSpringEnabled

public boolean isSpringEnabled()

Returns true if this distance joint is a spring distance joint.

Returns:

boolean

Since:

4.0.0

isSpringDamperEnabled

public boolean isSpringDamperEnabled()

Returns true if this distance joint is a spring distance joint with damping.

Returns:

boolean

Since:

4.0.0

getDampingRatio

public double getDampingRatio()

Returns the damping ratio.

Returns:

double

Since:

3.0.1

setDampingRatio

public void setDampingRatio(double dampingRatio)

Sets the damping ratio.

Larger values reduce the oscillation of the spring.

Parameters:

dampingRatio - the damping ratio; in the range [0, 1]

Throws:

IllegalArgumentException - if damping ration is less than zero or greater than 1

Since:

3.0.1

getFrequency

public double getFrequency()

Returns the spring frequency.

Returns:

double

Since:

3.0.1

setFrequency

public void setFrequency(double frequency)

Sets the spring frequency.

Larger values increase the stiffness of the spring.

Parameters:

frequency - the spring frequency in hz; must be greater than or equal to zero

Throws:

IllegalArgumentException - if frequency is less than zero

Since:

3.0.1

getReferenceAngle

public double getReferenceAngle()

Returns the reference angle.

The reference angle is the angle calculated when the joint was created from the two joined bodies. The reference angle is the angular difference between the bodies.

Returns:

double

Since:

3.0.1

setReferenceAngle

public void setReferenceAngle(double angle)

Sets the reference angle.

This method can be used to set the reference angle to override the computed reference angle from the constructor. This is useful in recreating the joint from a current state.

Parameters:

angle - the reference angle in radians

Since:

3.0.1

See Also:

getReferenceAngle()