org.jbox2d.dynamics
Class Body

java.lang.Object
  org.jbox2d.dynamics.Body

public class Body
extends Object

A rigid body. These are created via World.createBody.

Author:

Daniel Murphy

Field Summary

static int	e_activeFlag
static int	e_autoSleepFlag
static int	e_awakeFlag
static int	e_bulletFlag
static int	e_fixedRotationFlag
static int	e_islandFlag
static int	e_toiFlag
float	m_angularDamping
float	m_angularVelocity
ContactEdge	m_contactList
int	m_fixtureCount
Fixture	m_fixtureList
int	m_flags
Vec2	m_force
float	m_gravityScale
float	m_I
float	m_invI
float	m_invMass
int	m_islandIndex
JointEdge	m_jointList
float	m_linearDamping
Vec2	m_linearVelocity
float	m_mass
Body	m_next
Body	m_prev
float	m_sleepTime
Sweep	m_sweep The swept motion for CCD
float	m_torque
BodyType	m_type
Object	m_userData
World	m_world
Transform	m_xf The body origin transform.

Constructor Summary

Body(BodyDef bd, World world)

Method Summary

protected void	advance(float t)
void	applyAngularImpulse(float impulse) Apply an angular impulse.
void	applyForce(Vec2 force, Vec2 point) Apply a force at a world point.
void	applyForceToCenter(Vec2 force) Apply a force to the center of mass.
void	applyLinearImpulse(Vec2 impulse, Vec2 point) Apply an impulse at a point.
void	applyTorque(float torque) Apply a torque.
Fixture	createFixture(FixtureDef def) Creates a fixture and attach it to this body.
Fixture	createFixture(Shape shape, float density) Creates a fixture from a shape and attach it to this body.
void	destroyFixture(Fixture fixture) Destroy a fixture.
float	getAngle() Get the angle in radians.
float	getAngularDamping() Get the angular damping of the body.
float	getAngularVelocity() Get the angular velocity.
ContactEdge	getContactList() Get the list of all contacts attached to this body.
Fixture	getFixtureList() Get the list of all fixtures attached to this body.
float	getGravityScale() Get the gravity scale of the body.
float	getInertia() Get the central rotational inertia of the body.
JointEdge	getJointList() Get the list of all joints attached to this body.
float	getLinearDamping() Get the linear damping of the body.
Vec2	getLinearVelocity() Get the linear velocity of the center of mass.
Vec2	getLinearVelocityFromLocalPoint(Vec2 localPoint) Get the world velocity of a local point.
void	getLinearVelocityFromLocalPointToOut(Vec2 localPoint, Vec2 out)
Vec2	getLinearVelocityFromWorldPoint(Vec2 worldPoint) Get the world linear velocity of a world point attached to this body.
void	getLinearVelocityFromWorldPointToOut(Vec2 worldPoint, Vec2 out)
Vec2	getLocalCenter() Get the local position of the center of mass.
Vec2	getLocalPoint(Vec2 worldPoint) Gets a local point relative to the body's origin given a world point.
void	getLocalPointToOut(Vec2 worldPoint, Vec2 out)
Vec2	getLocalVector(Vec2 worldVector) Gets a local vector given a world vector.
void	getLocalVectorToOut(Vec2 worldVector, Vec2 out)
void	getLocalVectorToOutUnsafe(Vec2 worldVector, Vec2 out)
float	getMass() Get the total mass of the body.
void	getMassData(MassData data) Get the mass data of the body.
Body	getNext() Get the next body in the world's body list.
Vec2	getPosition() Get the world body origin position.
Transform	getTransform() Get the body transform for the body's origin.
BodyType	getType()
Object	getUserData() Get the user data pointer that was provided in the body definition.
World	getWorld() Get the parent world of this body.
Vec2	getWorldCenter() Get the world position of the center of mass.
Vec2	getWorldPoint(Vec2 localPoint) Get the world coordinates of a point given the local coordinates.
void	getWorldPointToOut(Vec2 localPoint, Vec2 out)
Vec2	getWorldVector(Vec2 localVector) Get the world coordinates of a vector given the local coordinates.
void	getWorldVectorToOut(Vec2 localVector, Vec2 out)
void	getWorldVectorToOutUnsafe(Vec2 localVector, Vec2 out)
boolean	isActive() Get the active state of the body.
boolean	isAwake() Get the sleeping state of this body.
boolean	isBullet() Is this body treated like a bullet for continuous collision detection?
boolean	isFixedRotation() Does this body have fixed rotation?
boolean	isSleepingAllowed() Is this body allowed to sleep
void	resetMassData() This resets the mass properties to the sum of the mass properties of the fixtures.
void	setActive(boolean flag) Set the active state of the body.
void	setAngularDamping(float angularDamping) Set the angular damping of the body.
void	setAngularVelocity(float w) Set the angular velocity.
void	setAwake(boolean flag) Set the sleep state of the body.
void	setBullet(boolean flag) Should this body be treated like a bullet for continuous collision detection?
void	setFixedRotation(boolean flag) Set this body to have fixed rotation.
void	setGravityScale(float gravityScale) Set the gravity scale of the body.
void	setLinearDamping(float linearDamping) Set the linear damping of the body.
void	setLinearVelocity(Vec2 v) Set the linear velocity of the center of mass.
void	setMassData(MassData massData) Set the mass properties to override the mass properties of the fixtures.
void	setSleepingAllowed(boolean flag) You can disable sleeping on this body.
void	setTransform(Vec2 position, float angle) Set the position of the body's origin and rotation.
void	setType(BodyType type) Set the type of this body.
void	setUserData(Object data) Set the user data.
boolean	shouldCollide(Body other) This is used to prevent connected bodies from colliding.
protected void	synchronizeFixtures()
void	synchronizeTransform()

Methods inherited from class java.lang.Object

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

Field Detail

e_islandFlag

public static final int e_islandFlag

See Also:

Constant Field Values

e_awakeFlag

public static final int e_awakeFlag

See Also:

Constant Field Values

e_autoSleepFlag

public static final int e_autoSleepFlag

See Also:

Constant Field Values

e_bulletFlag

public static final int e_bulletFlag

See Also:

Constant Field Values

e_fixedRotationFlag

public static final int e_fixedRotationFlag

See Also:

Constant Field Values

e_activeFlag

public static final int e_activeFlag

See Also:

Constant Field Values

e_toiFlag

public static final int e_toiFlag

See Also:

Constant Field Values

m_type

public BodyType m_type

m_flags

public int m_flags

m_islandIndex

public int m_islandIndex

m_xf

public final Transform m_xf

The body origin transform.

m_sweep

public final Sweep m_sweep

The swept motion for CCD

m_linearVelocity

public final Vec2 m_linearVelocity

m_angularVelocity

public float m_angularVelocity

m_force

public final Vec2 m_force

m_torque

public float m_torque

m_world

public World m_world

m_prev

public Body m_prev

m_next

public Body m_next

m_fixtureList

public Fixture m_fixtureList

m_fixtureCount

public int m_fixtureCount

m_jointList

public JointEdge m_jointList

m_contactList

public ContactEdge m_contactList

m_mass

public float m_mass

m_invMass

public float m_invMass

m_I

public float m_I

m_invI

public float m_invI

m_linearDamping

public float m_linearDamping

m_angularDamping

public float m_angularDamping

m_gravityScale

public float m_gravityScale

m_sleepTime

public float m_sleepTime

m_userData

public Object m_userData

Constructor Detail

Body

public Body(BodyDef bd,
            World world)

Method Detail

createFixture

public final Fixture createFixture(FixtureDef def)

Creates a fixture and attach it to this body. Use this function if you need to set some fixture parameters, like friction. Otherwise you can create the fixture directly from a shape. If the density is non-zero, this function automatically updates the mass of the body. Contacts are not created until the next time step.

Parameters:

def - the fixture definition.

createFixture

public final Fixture createFixture(Shape shape,
                                   float density)

Creates a fixture from a shape and attach it to this body. This is a convenience function. Use FixtureDef if you need to set parameters like friction, restitution, user data, or filtering. If the density is non-zero, this function automatically updates the mass of the body.

Parameters:

shape - the shape to be cloned.

density - the shape density (set to zero for static bodies).

destroyFixture

public final void destroyFixture(Fixture fixture)

Destroy a fixture. This removes the fixture from the broad-phase and destroys all contacts associated with this fixture. This will automatically adjust the mass of the body if the body is dynamic and the fixture has positive density. All fixtures attached to a body are implicitly destroyed when the body is destroyed.

Parameters:

fixture - the fixture to be removed.

setTransform

public final void setTransform(Vec2 position,
                               float angle)

Set the position of the body's origin and rotation. This breaks any contacts and wakes the other bodies. Manipulating a body's transform may cause non-physical behavior.

Parameters:

position - the world position of the body's local origin.

angle - the world rotation in radians.

getTransform

public final Transform getTransform()

Get the body transform for the body's origin.

Returns:

the world transform of the body's origin.

getPosition

public final Vec2 getPosition()

Get the world body origin position. Do not modify.

Returns:

the world position of the body's origin.

getAngle

public final float getAngle()

Get the angle in radians.

Returns:

the current world rotation angle in radians.

getWorldCenter

public final Vec2 getWorldCenter()

Get the world position of the center of mass. Do not modify.

getLocalCenter

public final Vec2 getLocalCenter()

Get the local position of the center of mass. Do not modify.

setLinearVelocity

public final void setLinearVelocity(Vec2 v)

Set the linear velocity of the center of mass.

Parameters:

v - the new linear velocity of the center of mass.

getLinearVelocity

public final Vec2 getLinearVelocity()

Get the linear velocity of the center of mass. Do not modify, instead use setLinearVelocity(Vec2).

Returns:

the linear velocity of the center of mass.

setAngularVelocity

public final void setAngularVelocity(float w)

Set the angular velocity.

Parameters:

omega - the new angular velocity in radians/second.

getAngularVelocity

public final float getAngularVelocity()

Get the angular velocity.

Returns:

the angular velocity in radians/second.

getGravityScale

public float getGravityScale()

Get the gravity scale of the body.

Returns:

setGravityScale

public void setGravityScale(float gravityScale)

Set the gravity scale of the body.

Parameters:

gravityScale -

applyForce

public final void applyForce(Vec2 force,
                             Vec2 point)

Apply a force at a world point. If the force is not applied at the center of mass, it will generate a torque and affect the angular velocity. This wakes up the body.

Parameters:

force - the world force vector, usually in Newtons (N).

point - the world position of the point of application.

applyForceToCenter

public final void applyForceToCenter(Vec2 force)

Apply a force to the center of mass. This wakes up the body.

Parameters:

force - the world force vector, usually in Newtons (N).

applyTorque

public final void applyTorque(float torque)

Apply a torque. This affects the angular velocity without affecting the linear velocity of the center of mass. This wakes up the body.

Parameters:

torque - about the z-axis (out of the screen), usually in N-m.

applyLinearImpulse

public final void applyLinearImpulse(Vec2 impulse,
                                     Vec2 point)

Apply an impulse at a point. This immediately modifies the velocity. It also modifies the angular velocity if the point of application is not at the center of mass. This wakes up the body.

Parameters:

impulse - the world impulse vector, usually in N-seconds or kg-m/s.

point - the world position of the point of application.

applyAngularImpulse

public void applyAngularImpulse(float impulse)

Apply an angular impulse.

Parameters:

impulse - the angular impulse in units of kg*m*m/s

getMass

public final float getMass()

Get the total mass of the body.

Returns:

the mass, usually in kilograms (kg).

getInertia

public final float getInertia()

Get the central rotational inertia of the body.

Returns:

the rotational inertia, usually in kg-m^2.

getMassData

public final void getMassData(MassData data)

Get the mass data of the body. The rotational inertia is relative to the center of mass.

setMassData

public final void setMassData(MassData massData)

Set the mass properties to override the mass properties of the fixtures. Note that this changes the center of mass position. Note that creating or destroying fixtures can also alter the mass. This function has no effect if the body isn't dynamic.

Parameters:

massData - the mass properties.

resetMassData

public final void resetMassData()

This resets the mass properties to the sum of the mass properties of the fixtures. This normally does not need to be called unless you called setMassData to override the mass and you later want to reset the mass.

getWorldPoint

public final Vec2 getWorldPoint(Vec2 localPoint)

Get the world coordinates of a point given the local coordinates.

Parameters:

localPoint - a point on the body measured relative the the body's origin.

Returns:

the same point expressed in world coordinates.

getWorldPointToOut

public final void getWorldPointToOut(Vec2 localPoint,
                                     Vec2 out)

getWorldVector

public final Vec2 getWorldVector(Vec2 localVector)

Get the world coordinates of a vector given the local coordinates.

Parameters:

localVector - a vector fixed in the body.

Returns:

the same vector expressed in world coordinates.

getWorldVectorToOut

public final void getWorldVectorToOut(Vec2 localVector,
                                      Vec2 out)

getWorldVectorToOutUnsafe

public final void getWorldVectorToOutUnsafe(Vec2 localVector,
                                            Vec2 out)

getLocalPoint

public final Vec2 getLocalPoint(Vec2 worldPoint)

Gets a local point relative to the body's origin given a world point.

Parameters:

a - point in world coordinates.

Returns:

the corresponding local point relative to the body's origin.

getLocalPointToOut

public final void getLocalPointToOut(Vec2 worldPoint,
                                     Vec2 out)

getLocalVector

public final Vec2 getLocalVector(Vec2 worldVector)

Gets a local vector given a world vector.

Parameters:

a - vector in world coordinates.

Returns:

the corresponding local vector.

getLocalVectorToOut

public final void getLocalVectorToOut(Vec2 worldVector,
                                      Vec2 out)

getLocalVectorToOutUnsafe

public final void getLocalVectorToOutUnsafe(Vec2 worldVector,
                                            Vec2 out)

getLinearVelocityFromWorldPoint

public final Vec2 getLinearVelocityFromWorldPoint(Vec2 worldPoint)

Get the world linear velocity of a world point attached to this body.

Parameters:

a - point in world coordinates.

Returns:

the world velocity of a point.

getLinearVelocityFromWorldPointToOut

public final void getLinearVelocityFromWorldPointToOut(Vec2 worldPoint,
                                                       Vec2 out)

getLinearVelocityFromLocalPoint

public final Vec2 getLinearVelocityFromLocalPoint(Vec2 localPoint)

Get the world velocity of a local point.

Parameters:

a - point in local coordinates.

Returns:

the world velocity of a point.

getLinearVelocityFromLocalPointToOut

public final void getLinearVelocityFromLocalPointToOut(Vec2 localPoint,
                                                       Vec2 out)

getLinearDamping

public final float getLinearDamping()

Get the linear damping of the body.

setLinearDamping

public final void setLinearDamping(float linearDamping)

Set the linear damping of the body.

getAngularDamping

public final float getAngularDamping()

Get the angular damping of the body.

setAngularDamping

public final void setAngularDamping(float angularDamping)

Set the angular damping of the body.

getType

public BodyType getType()

setType

public void setType(BodyType type)

Set the type of this body. This may alter the mass and velocity.

Parameters:

type -

isBullet

public final boolean isBullet()

Is this body treated like a bullet for continuous collision detection?

setBullet

public final void setBullet(boolean flag)

Should this body be treated like a bullet for continuous collision detection?

setSleepingAllowed

public void setSleepingAllowed(boolean flag)

You can disable sleeping on this body. If you disable sleeping, the body will be woken.

Parameters:

flag -

isSleepingAllowed

public boolean isSleepingAllowed()

Is this body allowed to sleep

Returns:

setAwake

public void setAwake(boolean flag)

Set the sleep state of the body. A sleeping body has very low CPU cost.

Parameters:

flag - set to true to put body to sleep, false to wake it.

flag -

isAwake

public boolean isAwake()

Get the sleeping state of this body.

Returns:

true if the body is sleeping.

setActive

public void setActive(boolean flag)

Set the active state of the body. An inactive body is not simulated and cannot be collided with or woken up. If you pass a flag of true, all fixtures will be added to the broad-phase. If you pass a flag of false, all fixtures will be removed from the broad-phase and all contacts will be destroyed. Fixtures and joints are otherwise unaffected. You may continue to create/destroy fixtures and joints on inactive bodies. Fixtures on an inactive body are implicitly inactive and will not participate in collisions, ray-casts, or queries. Joints connected to an inactive body are implicitly inactive. An inactive body is still owned by a World object and remains in the body list.

Parameters:

flag -

isActive

public boolean isActive()

Get the active state of the body.

Returns:

setFixedRotation

public void setFixedRotation(boolean flag)

Set this body to have fixed rotation. This causes the mass to be reset.

Parameters:

flag -

isFixedRotation

public boolean isFixedRotation()

Does this body have fixed rotation?

Returns:

getFixtureList

public final Fixture getFixtureList()

Get the list of all fixtures attached to this body.

getJointList

public final JointEdge getJointList()

Get the list of all joints attached to this body.

getContactList

public final ContactEdge getContactList()

Get the list of all contacts attached to this body.

getNext

public final Body getNext()

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

getUserData

public final Object getUserData()

Get the user data pointer that was provided in the body definition.

setUserData

public final void setUserData(Object data)

Set the user data. Use this to store your application specific data.

getWorld

public final World getWorld()

Get the parent world of this body.

synchronizeFixtures

protected final void synchronizeFixtures()

synchronizeTransform

public final void synchronizeTransform()

shouldCollide

public boolean shouldCollide(Body other)

This is used to prevent connected bodies from colliding. It may lie, depending on the collideConnected flag.

Parameters:

other -

Returns:

advance

protected final void advance(float t)