org.jbox2d.dynamics.contacts
Class Contact

java.lang.Object
  org.jbox2d.dynamics.contacts.Contact

Direct Known Subclasses:

ChainAndCircleContact, ChainAndPolygonContact, CircleContact, EdgeAndCircleContact, EdgeAndPolygonContact, PolygonAndCircleContact, PolygonContact

public abstract class Contact
extends Object

The class manages contact between two shapes. A contact exists for each overlapping AABB in the broad-phase (except if filtered). Therefore a contact object may exist that has no contact points.

Author:

daniel

Field Summary

static int	BULLET_HIT_FLAG
static int	ENABLED_FLAG
static int	FILTER_FLAG
static int	ISLAND_FLAG
Fixture	m_fixtureA
Fixture	m_fixtureB
int	m_flags
float	m_friction
int	m_indexA
int	m_indexB
Manifold	m_manifold
Contact	m_next
ContactEdge	m_nodeA
ContactEdge	m_nodeB
Contact	m_prev
float	m_restitution
float	m_tangentSpeed
float	m_toi
float	m_toiCount
protected IWorldPool	pool
static int	TOI_FLAG
static int	TOUCHING_FLAG

Constructor Summary

protected

Contact(IWorldPool argPool)

Method Summary

abstract void	evaluate(Manifold manifold, Transform xfA, Transform xfB)
void	flagForFiltering() Flag this contact for filtering.
int	getChildIndexA()
int	getChildIndexB()
Fixture	getFixtureA() Get the first fixture in this contact.
Fixture	getFixtureB() Get the second fixture in this contact.
float	getFriction()
Manifold	getManifold() Get the contact manifold.
Contact	getNext() Get the next contact in the world's contact list.
float	getRestitution()
float	getTangentSpeed()
void	getWorldManifold(WorldManifold worldManifold) Get the world manifold.
void	init(Fixture fA, int indexA, Fixture fB, int indexB) initialization for pooling
boolean	isEnabled() Has this contact been disabled?
boolean	isTouching() Is this contact touching
static float	mixFriction(float friction1, float friction2) Friction mixing law.
static float	mixRestitution(float restitution1, float restitution2) Restitution mixing law.
void	resetFriction()
void	resetRestitution()
void	setEnabled(boolean flag) Enable/disable this contact.
void	setFriction(float friction)
void	setRestitution(float restitution)
void	setTangentSpeed(float speed)
void	update(ContactListener listener)

Methods inherited from class java.lang.Object

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

Field Detail

ISLAND_FLAG

public static final int ISLAND_FLAG

See Also:

Constant Field Values

TOUCHING_FLAG

public static final int TOUCHING_FLAG

See Also:

Constant Field Values

ENABLED_FLAG

public static final int ENABLED_FLAG

See Also:

Constant Field Values

FILTER_FLAG

public static final int FILTER_FLAG

See Also:

Constant Field Values

BULLET_HIT_FLAG

public static final int BULLET_HIT_FLAG

See Also:

Constant Field Values

TOI_FLAG

public static final int TOI_FLAG

See Also:

Constant Field Values

m_flags

public int m_flags

m_prev

public Contact m_prev

m_next

public Contact m_next

m_nodeA

public ContactEdge m_nodeA

m_nodeB

public ContactEdge m_nodeB

m_fixtureA

public Fixture m_fixtureA

m_fixtureB

public Fixture m_fixtureB

m_indexA

public int m_indexA

m_indexB

public int m_indexB

m_manifold

public final Manifold m_manifold

m_toiCount

public float m_toiCount

m_toi

public float m_toi

m_friction

public float m_friction

m_restitution

public float m_restitution

m_tangentSpeed

public float m_tangentSpeed

pool

protected final IWorldPool pool

Constructor Detail

Contact

protected Contact(IWorldPool argPool)

Method Detail

init

public void init(Fixture fA,
                 int indexA,
                 Fixture fB,
                 int indexB)

initialization for pooling

getManifold

public Manifold getManifold()

Get the contact manifold. Do not set the point count to zero. Instead call Disable.

getWorldManifold

public void getWorldManifold(WorldManifold worldManifold)

Get the world manifold.

isTouching

public boolean isTouching()

Is this contact touching

Returns:

setEnabled

public void setEnabled(boolean flag)

Enable/disable this contact. This can be used inside the pre-solve contact listener. The contact is only disabled for the current time step (or sub-step in continuous collisions).

Parameters:

flag -

isEnabled

public boolean isEnabled()

Has this contact been disabled?

Returns:

getNext

public Contact getNext()

Get the next contact in the world's contact list.

Returns:

getFixtureA

public Fixture getFixtureA()

Get the first fixture in this contact.

Returns:

getChildIndexA

public int getChildIndexA()

getFixtureB

public Fixture getFixtureB()

Get the second fixture in this contact.

Returns:

getChildIndexB

public int getChildIndexB()

setFriction

public void setFriction(float friction)

getFriction

public float getFriction()

resetFriction

public void resetFriction()

setRestitution

public void setRestitution(float restitution)

getRestitution

public float getRestitution()

resetRestitution

public void resetRestitution()

setTangentSpeed

public void setTangentSpeed(float speed)

getTangentSpeed

public float getTangentSpeed()

evaluate

public abstract void evaluate(Manifold manifold,
                              Transform xfA,
                              Transform xfB)

flagForFiltering

public void flagForFiltering()

Flag this contact for filtering. Filtering will occur the next time step.

update

public void update(ContactListener listener)

mixFriction

public static final float mixFriction(float friction1,
                                      float friction2)

Friction mixing law. The idea is to allow either fixture to drive the restitution to zero. For example, anything slides on ice.

Parameters:

friction1 -

friction2 -

Returns:

mixRestitution

public static final float mixRestitution(float restitution1,
                                         float restitution2)

Restitution mixing law. The idea is allow for anything to bounce off an inelastic surface. For example, a superball bounces on anything.

Parameters:

restitution1 -

restitution2 -

Returns: