| Box2D 2.2.1 A 2D Physics Engine for Games

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b2Body Class Reference

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

`#include <b2Body.h>`

List of all members.

## Public Member Functions

b2Fixture * | CreateFixture (const b2FixtureDef *def)
b2Fixture * | CreateFixture (const b2Shape *shape, float32 density)
void | DestroyFixture (b2Fixture *fixture)
void | SetTransform (const b2Vec2 &position, float32 angle)
const b2Transform & | GetTransform () const
const b2Vec2 & | GetPosition () const
float32 | 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)
b2Vec2 | GetLinearVelocity () const
void | SetAngularVelocity (float32 omega)
float32 | GetAngularVelocity () const
void | ApplyForce (const b2Vec2 &force, const b2Vec2 &point)
void | ApplyForceToCenter (const b2Vec2 &force)
void | ApplyTorque (float32 torque)
void | ApplyLinearImpulse (const b2Vec2 &impulse, const b2Vec2 &point)
void | ApplyAngularImpulse (float32 impulse)
float32 | GetMass () const
float32 | GetInertia () const
void | GetMassData (b2MassData *data) 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
float32 | GetLinearDamping () const
| Get the linear damping of the body.
void | SetLinearDamping (float32 linearDamping)
| Set the linear damping of the body.
float32 | GetAngularDamping () const
| Get the angular damping of the body.
void | SetAngularDamping (float32 angularDamping)
| Set the angular damping of the body.
float32 | GetGravityScale () const
| Get the gravity scale of the body.
void | SetGravityScale (float32 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 | SetActive (bool flag)
bool | IsActive () 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
void * | GetUserData () const
| Get the user data pointer that was provided in the body definition.
void | SetUserData (void *data)
| Set the user data. Use this to store your application specific data.
b2World * | GetWorld ()
| Get the parent world of this body.
const b2World * | GetWorld () const
void | Dump ()
| Dump this body to a log file.

## Friends

class | b2World
class | b2Island
class | b2ContactManager
class | b2ContactSolver
class | b2Contact
class | b2DistanceJoint
class | b2GearJoint
class | b2WheelJoint
class | b2MouseJoint
class | b2PrismaticJoint
class | b2PulleyJoint
class | b2RevoluteJoint
class | b2WeldJoint
class | b2FrictionJoint
class | b2RopeJoint

## Detailed Description

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

## Member Function Documentation

void b2Body::ApplyAngularImpulse | ( | float32 | impulse | ) | `[inline]`

Apply an angular impulse.

Parameters:

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

void b2Body::ApplyForce | ( | const b2Vec2 & | force,
|  | const b2Vec2 & | point
| ) |  | `[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.

void b2Body::ApplyForceToCenter | ( | const b2Vec2 & | force | ) | `[inline]`

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

Parameters:

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

void b2Body::ApplyLinearImpulse | ( | const b2Vec2 & | impulse,
|  | const b2Vec2 & | point
| ) |  | `[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.

void b2Body::ApplyTorque | ( | float32 | torque | ) | `[inline]`

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.

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.

b2Fixture * b2Body::CreateFixture | ( | const b2Shape * | shape,
|  | float32 | 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.

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.

float32 b2Body::GetAngle | ( |  | ) | const`[inline]`

Get the angle in radians.

Returns:
  the current world rotation angle in radians.

float32 b2Body::GetAngularVelocity | ( |  | ) | const`[inline]`

Get the angular velocity.

Returns:
  the angular velocity in radians/second.

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.

float32 b2Body::GetInertia | ( |  | ) | const`[inline]`

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

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

b2Vec2 b2Body::GetLinearVelocity | ( |  | ) | const`[inline]`

Get the linear velocity of the center of mass.

Returns:
  the linear velocity of the center of mass.

b2Vec2 b2Body::GetLinearVelocityFromLocalPoint | ( | const b2Vec2 & | localPoint | ) | const`[inline]`

Get the world velocity of a local point.

Parameters:

  a | point in local coordinates.

Returns:
  the world velocity of a point.

b2Vec2 b2Body::GetLinearVelocityFromWorldPoint | ( | const b2Vec2 & | worldPoint | ) | const`[inline]`

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.

b2Vec2 b2Body::GetLocalPoint | ( | const b2Vec2 & | worldPoint | ) | const`[inline]`

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.

b2Vec2 b2Body::GetLocalVector | ( | const b2Vec2 & | worldVector | ) | const`[inline]`

Gets a local vector given a world vector.

Parameters:

  a | vector in world coordinates.

Returns:
  the corresponding local vector.

float32 b2Body::GetMass | ( |  | ) | const`[inline]`

Get the total mass of the body.

Returns:
  the mass, usually in kilograms (kg).

void b2Body::GetMassData | ( | b2MassData * | data | ) | const`[inline]`

Get the mass data of the body.

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

const b2Vec2 & b2Body::GetPosition | ( |  | ) | const`[inline]`

Get the world body origin position.

Returns:
  the world position of the body's origin.

const b2Transform & b2Body::GetTransform | ( |  | ) | const`[inline]`

Get the body transform for the body's origin.

Returns:
  the world transform of the body's origin.

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.

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.

bool b2Body::IsAwake | ( |  | ) | const`[inline]`

Get the sleeping state of this body.

Returns:
  true if the body is sleeping.

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.

void b2Body::SetActive | ( | bool | 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 b2World object and remains in the body list.

void b2Body::SetAngularVelocity | ( | float32 | omega | ) | `[inline]`

Set the angular velocity.

Parameters:

  omega | the new angular velocity in radians/second.

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 put body to sleep, false to wake it.

void b2Body::SetFixedRotation | ( | bool | flag | ) | `[inline]`

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

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.

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:

  massData | the mass properties.

void b2Body::SetSleepingAllowed | ( | bool | flag | ) | `[inline]`

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

void b2Body::SetTransform | ( | const b2Vec2 & | position,
|  | float32 | 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.

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

- b2Body.h
- b2Body.cpp

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