b2World Class Reference

#include <b2World.h>

Public Member Functions
	b2World (const b2Vec2 &gravity)
	~b2World ()
	Destruct the world. All physics entities are destroyed and all heap memory is released.
void	SetDestructionListener (b2DestructionListener *listener)
void	SetContactFilter (b2ContactFilter *filter)
void	SetContactListener (b2ContactListener *listener)
void	SetDebugDraw (b2Draw *debugDraw)
b2Body *	CreateBody (const b2BodyDef *def)
void	DestroyBody (b2Body *body)
b2Joint *	CreateJoint (const b2JointDef *def)
void	DestroyJoint (b2Joint *joint)
b2ParticleSystem *	CreateParticleSystem (const b2ParticleSystemDef *def)
void	DestroyParticleSystem (b2ParticleSystem *p)
void	Step (float32 timeStep, int32 velocityIterations, int32 positionIterations, int32 particleIterations)
void	Step (float32 timeStep, int32 velocityIterations, int32 positionIterations)
int	CalculateReasonableParticleIterations (float32 timeStep) const
void	ClearForces ()
void	DrawDebugData ()
	Call this to draw shapes and other debug draw data. This is intentionally non-const.
void	QueryAABB (b2QueryCallback *callback, const b2AABB &aabb) const
void	QueryShapeAABB (b2QueryCallback *callback, const b2Shape &shape, const b2Transform &xf) const
void	RayCast (b2RayCastCallback *callback, const b2Vec2 &point1, const b2Vec2 &point2) const
b2Body *	GetBodyList ()
const b2Body *	GetBodyList () const
b2Joint *	GetJointList ()
const b2Joint *	GetJointList () const
b2ParticleSystem *	GetParticleSystemList ()
const b2ParticleSystem *	GetParticleSystemList () const
b2Contact *	GetContactList ()
const b2Contact *	GetContactList () const
void	SetAllowSleeping (bool flag)
	Enable/disable sleep.
bool	GetAllowSleeping () const
void	SetWarmStarting (bool flag)
	Enable/disable warm starting. For testing.
bool	GetWarmStarting () const
void	SetContinuousPhysics (bool flag)
	Enable/disable continuous physics. For testing.
bool	GetContinuousPhysics () const
void	SetSubStepping (bool flag)
	Enable/disable single stepped continuous physics. For testing.
bool	GetSubStepping () const
int32	GetProxyCount () const
	Get the number of broad-phase proxies.
int32	GetBodyCount () const
	Get the number of bodies.
int32	GetJointCount () const
	Get the number of joints.
int32	GetContactCount () const
	Get the number of contacts (each may have 0 or more contact points).
int32	GetTreeHeight () const
	Get the height of the dynamic tree.
int32	GetTreeBalance () const
	Get the balance of the dynamic tree.
float32	GetTreeQuality () const
void	SetGravity (const b2Vec2 &gravity)
	Change the global gravity vector.
b2Vec2	GetGravity () const
	Get the global gravity vector.
bool	IsLocked () const
	Is the world locked (in the middle of a time step).
void	SetAutoClearForces (bool flag)
	Set flag to control automatic clearing of forces after each time step.
bool	GetAutoClearForces () const
	Get the flag that controls automatic clearing of forces after each time step.
void	ShiftOrigin (const b2Vec2 &newOrigin)
const b2ContactManager &	GetContactManager () const
	Get the contact manager for testing.
const b2Profile &	GetProfile () const
	Get the current profile.
void	Dump ()
const b2Version *	GetVersion () const
	Get API version.
const char *	GetVersionString () const
	Get API version string.

Friends
class	b2Body
class	b2Fixture
class	b2ContactManager
class	b2Controller
class	b2ParticleSystem

Detailed Description

The world class manages all physics entities, dynamic simulation, and asynchronous queries. The world also contains efficient memory management facilities.

Constructor & Destructor Documentation

b2World::b2World

(

const b2Vec2 &

gravity

)

Construct a world object.

Parameters

gravity

the world gravity vector.

Member Function Documentation

int b2World::CalculateReasonableParticleIterations

(

float32

timeStep

)

const

Recommend a value to be used in Step for particleIterations. This calculation is necessarily a simplification and should only be used as a starting point. Please see "Particle Iterations" in the Programmer's Guide for details.

Parameters

timeStep

is the value to be passed into Step.

void b2World::ClearForces

(

)

Manually clear the force buffer on all bodies. By default, forces are cleared automatically after each call to Step. The default behavior is modified by calling SetAutoClearForces. The purpose of this function is to support sub-stepping. Sub-stepping is often used to maintain a fixed sized time step under a variable frame-rate. When you perform sub-stepping you will disable auto clearing of forces and instead call ClearForces after all sub-steps are complete in one pass of your game loop.

See Also

SetAutoClearForces

b2Body * b2World::CreateBody

(

const b2BodyDef *

def

)

Create a rigid body given a definition. No reference to the definition is retained.

Warning

This function is locked during callbacks.

b2Joint * b2World::CreateJoint

(

const b2JointDef *

def

)

Create a joint to constrain bodies together. No reference to the definition is retained. This may cause the connected bodies to cease colliding.

Warning

This function is locked during callbacks.

b2ParticleSystem * b2World::CreateParticleSystem

(

const b2ParticleSystemDef *

def

)

Create a particle system given a definition. No reference to the definition is retained.

Warning

This function is locked during callbacks.

void b2World::DestroyBody

(

b2Body *

body

)

Destroy a rigid body. This function is locked during callbacks.

Warning

This automatically deletes all associated shapes and joints.

This function is locked during callbacks.

void b2World::DestroyJoint

(

b2Joint *

joint

)

Destroy a joint. This may cause the connected bodies to begin colliding.

Warning

This function is locked during callbacks.

void b2World::DestroyParticleSystem

(

b2ParticleSystem *

p

)

Destroy a particle system.

Warning

This function is locked during callbacks.

void b2World::Dump

(

)

Dump the world into the log file.

Warning

this should be called outside of a time step.

b2Body * b2World::GetBodyList ( )

inline

Get the world body list. With the returned body, use b2Body::GetNext to get the next body in the world list. A NULL body indicates the end of the list.

Returns

the head of the world body list.

b2Contact * b2World::GetContactList ( )

inline

Get the world contact list. With the returned contact, use b2Contact::GetNext to get the next contact in the world list. A NULL contact indicates the end of the list.

Returns

the head of the world contact list.

Warning

contacts are created and destroyed in the middle of a time step. Use b2ContactListener to avoid missing contacts.

b2Joint * b2World::GetJointList ( )

inline

Get the world joint list. With the returned joint, use b2Joint::GetNext to get the next joint in the world list. A NULL joint indicates the end of the list.

Returns

the head of the world joint list.

b2ParticleSystem * b2World::GetParticleSystemList ( )

inline

Get the world particle-system list. With the returned body, use b2ParticleSystem::GetNext to get the next particle-system in the world list. A NULL particle-system indicates the end of the list.

Returns

the head of the world particle-system list.

float32 b2World::GetTreeQuality

(

)

const

Get the quality metric of the dynamic tree. The smaller the better. The minimum is 1.

void b2World::QueryAABB	(	b2QueryCallback *	callback,
		const b2AABB &	aabb
	)		const

Query the world for all fixtures that potentially overlap the provided AABB.

Parameters

callback	a user implemented callback class.
aabb	the query box.

void b2World::QueryShapeAABB	(	b2QueryCallback *	callback,
		const b2Shape &	shape,
		const b2Transform &	xf
	)		const

Query the world for all fixtures that potentially overlap the provided shape's AABB. Calls QueryAABB internally.

Parameters

callback	a user implemented callback class.
shape	the query shape
xf	the transform of the AABB

void b2World::RayCast	(	b2RayCastCallback *	callback,
		const b2Vec2 &	point1,
		const b2Vec2 &	point2
	)		const

Ray-cast the world for all fixtures in the path of the ray. Your callback controls whether you get the closest point, any point, or n-points. The ray-cast ignores shapes that contain the starting point.

Parameters

callback	a user implemented callback class.
point1	the ray starting point
point2	the ray ending point

void b2World::SetContactFilter

(

b2ContactFilter *

filter

)

Register a contact filter to provide specific control over collision. Otherwise the default filter is used (b2_defaultFilter). The listener is owned by you and must remain in scope.

void b2World::SetContactListener

(

b2ContactListener *

listener

)

Register a contact event listener. The listener is owned by you and must remain in scope.

void b2World::SetDebugDraw

(

b2Draw *

debugDraw

)

Register a routine for debug drawing. The debug draw functions are called inside with b2World::DrawDebugData method. The debug draw object is owned by you and must remain in scope.

void b2World::SetDestructionListener

(

b2DestructionListener *

listener

)

Register a destruction listener. The listener is owned by you and must remain in scope.

void b2World::ShiftOrigin

(

const b2Vec2 &

newOrigin

)

Shift the world origin. Useful for large worlds. The body shift formula is: position -= newOrigin

Parameters

newOrigin

the new origin with respect to the old origin

void b2World::Step	(	float32	timeStep,
		int32	velocityIterations,
		int32	positionIterations,
		int32	particleIterations
	)

Take a time step. This performs collision detection, integration, and constraint solution. For the numerical stability of particles, minimize the following dimensionless gravity acceleration: gravity / particleRadius * (timeStep / particleIterations)^2 b2CalculateParticleIterations() or CalculateReasonableParticleIterations() help to determine the optimal particleIterations.

Parameters

timeStep	the amount of time to simulate, this should not vary.
velocityIterations	for the velocity constraint solver.
positionIterations	for the position constraint solver.
particleIterations	for the particle simulation.

void b2World::Step ( float32  timeStep, int32  velocityIterations, int32  positionIterations  )

inline

Take a time step. This performs collision detection, integration, and constraint solution.

Parameters

timeStep	the amount of time to simulate, this should not vary.
velocityIterations	for the velocity constraint solver.
positionIterations	for the position constraint solver.

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

• b2World.h
• b2World.cpp