Box2D: b2Body Class Reference

| Box2D 2.4.1 A 2D physics engine for games

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Public Member Functions | Friends | List of all members
b2Body Class Reference

A rigid body. These are created via b2World::CreateBody. More...

`#include <b2_body.h>`

## Public Member Functions
b2Fixture * | CreateFixture (const b2FixtureDef *def)
b2Fixture * | CreateFixture (const b2Shape *shape, float density)
void | DestroyFixture (b2Fixture *fixture)
void | SetTransform (const b2Vec2 &position, float angle)
const b2Transform & | GetTransform () const
const b2Vec2 & | GetPosition () const
float | GetAngle () const
const b2Vec2 & | GetWorldCenter () const
| Get the world position of the center of mass.
const b2Vec2 & | GetLocalCenter () const
| Get the local position of the center of mass.
void | SetLinearVelocity (const b2Vec2 &v)
const b2Vec2 & | GetLinearVelocity () const
void | SetAngularVelocity (float omega)
float | GetAngularVelocity () const
void | ApplyForce (const b2Vec2 &force, const b2Vec2 &point, bool wake)
void | ApplyForceToCenter (const b2Vec2 &force, bool wake)
void | ApplyTorque (float torque, bool wake)
void | ApplyLinearImpulse (const b2Vec2 &impulse, const b2Vec2 &point, bool wake)
void | ApplyLinearImpulseToCenter (const b2Vec2 &impulse, bool wake)
void | ApplyAngularImpulse (float impulse, bool wake)
float | GetMass () const
float | GetInertia () const
b2MassData | GetMassData () const
void | SetMassData (const b2MassData *data)
void | ResetMassData ()
b2Vec2 | GetWorldPoint (const b2Vec2 &localPoint) const
b2Vec2 | GetWorldVector (const b2Vec2 &localVector) const
b2Vec2 | GetLocalPoint (const b2Vec2 &worldPoint) const
b2Vec2 | GetLocalVector (const b2Vec2 &worldVector) const
b2Vec2 | GetLinearVelocityFromWorldPoint (const b2Vec2 &worldPoint) const
b2Vec2 | GetLinearVelocityFromLocalPoint (const b2Vec2 &localPoint) const
float | GetLinearDamping () const
| Get the linear damping of the body.
void | SetLinearDamping (float linearDamping)
| Set the linear damping of the body.
float | GetAngularDamping () const
| Get the angular damping of the body.
void | SetAngularDamping (float angularDamping)
| Set the angular damping of the body.
float | GetGravityScale () const
| Get the gravity scale of the body.
void | SetGravityScale (float scale)
| Set the gravity scale of the body.
void | SetType (b2BodyType type)
| Set the type of this body. This may alter the mass and velocity.
b2BodyType | GetType () const
| Get the type of this body.
void | SetBullet (bool flag)
| Should this body be treated like a bullet for continuous collision detection?
bool | IsBullet () const
| Is this body treated like a bullet for continuous collision detection?
void | SetSleepingAllowed (bool flag)
bool | IsSleepingAllowed () const
| Is this body allowed to sleep.
void | SetAwake (bool flag)
bool | IsAwake () const
void | SetEnabled (bool flag)
bool | IsEnabled () const
| Get the active state of the body.
void | SetFixedRotation (bool flag)
bool | IsFixedRotation () const
| Does this body have fixed rotation?
b2Fixture * | GetFixtureList ()
| Get the list of all fixtures attached to this body.
const b2Fixture * | GetFixtureList () const
b2JointEdge * | GetJointList ()
| Get the list of all joints attached to this body.
const b2JointEdge * | GetJointList () const
b2ContactEdge * | GetContactList ()
const b2ContactEdge * | GetContactList () const
b2Body * | GetNext ()
| Get the next body in the world's body list.
const b2Body * | GetNext () const
b2BodyUserData & | GetUserData ()
| Get the user data pointer that was provided in the body definition.
const b2BodyUserData & | GetUserData () const
b2World * | GetWorld ()
| Get the parent world of this body.
const b2World * | GetWorld () const
void | Dump ()
| Dump this body to a file.

## Friends
class | b2World
class | b2Island
class | b2ContactManager
class | b2ContactSolver
class | b2Contact
class | b2DistanceJoint
class | b2FrictionJoint
class | b2GearJoint
class | b2MotorJoint
class | b2MouseJoint
class | b2PrismaticJoint
class | b2PulleyJoint
class | b2RevoluteJoint
class | b2WeldJoint
class | b2WheelJoint

## Detailed Description

A rigid body. These are created via b2World::CreateBody.

## Member Function Documentation

## ◆ ApplyAngularImpulse()

void b2Body::ApplyAngularImpulse | ( | float | impulse,
|  | bool | wake
| ) |  |
| inline

Apply an angular impulse.

Parameters

  impulse | the angular impulse in units of kg*m*m/s
  wake | also wake up the body

## ◆ ApplyForce()

void b2Body::ApplyForce | ( | const b2Vec2 & | force,
|  | const b2Vec2 & | point,
|  | bool | wake
| ) |  |
| inline

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.
  wake | also wake up the body

## ◆ ApplyForceToCenter()

void b2Body::ApplyForceToCenter | ( | const b2Vec2 & | force,
|  | bool | wake
| ) |  |
| inline

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

Parameters

  force | the world force vector, usually in Newtons (N).
  wake | also wake up the body

## ◆ ApplyLinearImpulse()

void b2Body::ApplyLinearImpulse | ( | const b2Vec2 & | impulse,
|  | const b2Vec2 & | point,
|  | bool | wake
| ) |  |
| inline

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.
  wake | also wake up the body

## ◆ ApplyLinearImpulseToCenter()

void b2Body::ApplyLinearImpulseToCenter | ( | const b2Vec2 & | impulse,
|  | bool | wake
| ) |  |
| inline

Apply an impulse to the center of mass. This immediately modifies the velocity.

Parameters

  impulse | the world impulse vector, usually in N-seconds or kg-m/s.
  wake | also wake up the body

## ◆ ApplyTorque()

void b2Body::ApplyTorque | ( | float | torque,
|  | bool | wake
| ) |  |
| inline

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

Parameters

  torque | about the z-axis (out of the screen), usually in N-m.
  wake | also wake up the body

## ◆ CreateFixture() [1/2]

b2Fixture * b2Body::CreateFixture | ( | const b2FixtureDef * | 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.

Warning
  This function is locked during callbacks.

## ◆ CreateFixture() [2/2]

b2Fixture * b2Body::CreateFixture | ( | const b2Shape * | shape,
|  | float | density
| ) |  |

Creates a fixture from a shape and attach it to this body. This is a convenience function. Use b2FixtureDef 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).

Warning
  This function is locked during callbacks.

## ◆ DestroyFixture()

void b2Body::DestroyFixture | ( | b2Fixture * | 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.

Warning
  This function is locked during callbacks.

## ◆ GetAngle()

float b2Body::GetAngle | ( |  | ) | const
| inline

Get the angle in radians.

Returns
  the current world rotation angle in radians.

## ◆ GetAngularVelocity()

float b2Body::GetAngularVelocity | ( |  | ) | const
| inline

Get the angular velocity.

Returns
  the angular velocity in radians/second.

## ◆ GetContactList()

b2ContactEdge * b2Body::GetContactList | ( |  | ) |
| inline

Get the list of all contacts attached to this body.

Warning
  this list changes during the time step and you may miss some collisions if you don't use b2ContactListener.

## ◆ GetInertia()

float b2Body::GetInertia | ( |  | ) | const
| inline

Get the rotational inertia of the body about the local origin.

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

## ◆ GetLinearVelocity()

const b2Vec2 & b2Body::GetLinearVelocity | ( |  | ) | const
| inline

Get the linear velocity of the center of mass.

Returns
  the linear velocity of the center of mass.

## ◆ GetLinearVelocityFromLocalPoint()

b2Vec2 b2Body::GetLinearVelocityFromLocalPoint | ( | const b2Vec2 & | localPoint | ) | const
| inline

Get the world velocity of a local point.

Parameters

  localPoint | a point in local coordinates.

Returns
  the world velocity of a point.

## ◆ GetLinearVelocityFromWorldPoint()

b2Vec2 b2Body::GetLinearVelocityFromWorldPoint | ( | const b2Vec2 & | worldPoint | ) | const
| inline

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

Parameters

  worldPoint | a point in world coordinates.

Returns
  the world velocity of a point.

## ◆ GetLocalPoint()

b2Vec2 b2Body::GetLocalPoint | ( | const b2Vec2 & | worldPoint | ) | const
| inline

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

Parameters

  worldPoint | a point in world coordinates.

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

## ◆ GetLocalVector()

b2Vec2 b2Body::GetLocalVector | ( | const b2Vec2 & | worldVector | ) | const
| inline

Gets a local vector given a world vector.

Parameters

  worldVector | a vector in world coordinates.

Returns
  the corresponding local vector.

## ◆ GetMass()

float b2Body::GetMass | ( |  | ) | const
| inline

Get the total mass of the body.

Returns
  the mass, usually in kilograms (kg).

## ◆ GetMassData()

b2MassData b2Body::GetMassData | ( |  | ) | const
| inline

Get the mass data of the body.

Returns
  a struct containing the mass, inertia and center of the body.

## ◆ GetPosition()

const b2Vec2 & b2Body::GetPosition | ( |  | ) | const
| inline

Get the world body origin position.

Returns
  the world position of the body's origin.

## ◆ GetTransform()

const b2Transform & b2Body::GetTransform | ( |  | ) | const
| inline

Get the body transform for the body's origin.

Returns
  the world transform of the body's origin.

## ◆ GetWorldPoint()

b2Vec2 b2Body::GetWorldPoint | ( | const b2Vec2 & | localPoint | ) | const
| inline

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.

## ◆ GetWorldVector()

b2Vec2 b2Body::GetWorldVector | ( | const b2Vec2 & | localVector | ) | const
| inline

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.

## ◆ IsAwake()

bool b2Body::IsAwake | ( |  | ) | const
| inline

Get the sleeping state of this body.

Returns
  true if the body is awake.

## ◆ ResetMassData()

void b2Body::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.

## ◆ SetAngularVelocity()

void b2Body::SetAngularVelocity | ( | float | omega | ) |
| inline

Set the angular velocity.

Parameters

  omega | the new angular velocity in radians/second.

## ◆ SetAwake()

void b2Body::SetAwake | ( | bool | flag | ) |
| inline

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

Parameters

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

## ◆ SetEnabled()

void b2Body::SetEnabled | ( | bool | flag | ) |

Allow a body to be disabled. A disabled 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 disabled bodies. Fixtures on a disabled body are implicitly disabled and will not participate in collisions, ray-casts, or queries. Joints connected to a disabled body are implicitly disabled. An diabled body is still owned by a b2World object and remains in the body list.

## ◆ SetFixedRotation()

void b2Body::SetFixedRotation | ( | bool | flag | ) |

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

## ◆ SetLinearVelocity()

void b2Body::SetLinearVelocity | ( | const b2Vec2 & | v | ) |
| inline

Set the linear velocity of the center of mass.

Parameters

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

## ◆ SetMassData()

void b2Body::SetMassData | ( | const b2MassData * | data | ) |

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

  data | the mass properties.

## ◆ SetSleepingAllowed()

void b2Body::SetSleepingAllowed | ( | bool | flag | ) |
| inline

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

## ◆ SetTransform()

void b2Body::SetTransform | ( | const b2Vec2 & | position,
|  | float | angle
| ) |  |

Set the position of the body's origin and rotation. Manipulating a body's transform may cause non-physical behavior. Note: contacts are updated on the next call to b2World::Step.

Parameters

  position | the world position of the body's local origin.
  angle | the world rotation in radians.

The documentation for this class was generated from the following file:

- /build/box2d/src/box2d-2.4.2/include/box2d/b2_body.h