b2DynamicTree Class Reference

#include <b2DynamicTree.h>

List of all members.

Public Member Functions
	b2DynamicTree ()
	Constructing the tree initializes the node pool.
	~b2DynamicTree ()
	Destroy the tree, freeing the node pool.
int32	CreateProxy (const b2AABB &aabb, void *userData)
	Create a proxy. Provide a tight fitting AABB and a userData pointer.
void	DestroyProxy (int32 proxyId)
	Destroy a proxy. This asserts if the id is invalid.
bool	MoveProxy (int32 proxyId, const b2AABB &aabb1, const b2Vec2 &displacement)
void	Rebalance (int32 iterations)
	Perform some iterations to re-balance the tree.
void *	GetUserData (int32 proxyId) const
const b2AABB &	GetFatAABB (int32 proxyId) const
	Get the fat AABB for a proxy.
int32	ComputeHeight () const
	Compute the height of the tree.
template<typename T >
void	Query (T *callback, const b2AABB &aabb) const
template<typename T >
void	RayCast (T *callback, const b2RayCastInput &input) const

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Detailed Description

A dynamic tree arranges data in a binary tree to accelerate queries such as volume queries and ray casts. Leafs are proxies with an AABB. In the tree we expand the proxy AABB by b2_fatAABBFactor so that the proxy AABB is bigger than the client object. This allows the client object to move by small amounts without triggering a tree update.

Nodes are pooled and relocatable, so we use node indices rather than pointers.

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Constructor & Destructor Documentation

b2DynamicTree::b2DynamicTree

(

)

Constructing the tree initializes the node pool.

b2DynamicTree::~b2DynamicTree

(

)

Destroy the tree, freeing the node pool.

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Member Function Documentation

int32 b2DynamicTree::ComputeHeight

(

)

const

Compute the height of the tree.

int32 b2DynamicTree::CreateProxy	(	const b2AABB &	aabb,
		void *	userData
	)

Create a proxy. Provide a tight fitting AABB and a userData pointer.

void b2DynamicTree::DestroyProxy

(

int32

proxyId

)

Destroy a proxy. This asserts if the id is invalid.

const b2AABB & b2DynamicTree::GetFatAABB

(

int32

proxyId

)

const [inline]

Get the fat AABB for a proxy.

void * b2DynamicTree::GetUserData

(

int32

proxyId

)

const [inline]

Get proxy user data.

Returns:

the proxy user data or 0 if the id is invalid.

bool b2DynamicTree::MoveProxy	(	int32	proxyId,
		const b2AABB &	aabb1,
		const b2Vec2 &	displacement
	)

Move a proxy with a swepted AABB. If the proxy has moved outside of its fattened AABB, then the proxy is removed from the tree and re-inserted. Otherwise the function returns immediately.

Returns:

true if the proxy was re-inserted.

template<typename T >

void b2DynamicTree::Query	(	T *	callback,
		const b2AABB &	aabb
	)			const [inline]

Query an AABB for overlapping proxies. The callback class is called for each proxy that overlaps the supplied AABB.

template<typename T >

void b2DynamicTree::RayCast	(	T *	callback,
		const b2RayCastInput &	input
	)			const [inline]

Ray-cast against the proxies in the tree. This relies on the callback to perform a exact ray-cast in the case were the proxy contains a shape. The callback also performs the any collision filtering. This has performance roughly equal to k * log(n), where k is the number of collisions and n is the number of proxies in the tree.

Parameters:

	input	the ray-cast input data. The ray extends from p1 to p1 + maxFraction * (p2 - p1).
	callback	a callback class that is called for each proxy that is hit by the ray.

void b2DynamicTree::Rebalance

(

int32

iterations

)

Perform some iterations to re-balance the tree.

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

• Box2D/Box2D/Collision/b2DynamicTree.h
• Box2D/Box2D/Collision/b2DynamicTree.cpp