#include <b2DynamicTree.h>

Public Member Functions
	b2DynamicTree ()
	Constructing the tree initializes 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.
float32	GetAreaRatio () const
	Get the ratio of the sum of the node areas to the root area.
const b2AABB &	GetFatAABB (int32 proxyId) const
	Get the fat AABB for a proxy.
int32	GetHeight () const
int32	GetMaxBalance () const
void *	GetUserData (int32 proxyId) const
bool	MoveProxy (int32 proxyId, const b2AABB &aabb1, const b2Vec2 &displacement)
template<typename T >
void	Query (T *callback, const b2AABB &aabb) const
template<typename T >
void	RayCast (T *callback, const b2RayCastInput &input) const
void	RebuildBottomUp ()
	Build an optimal tree. Very expensive. For testing.
void	ShiftOrigin (const b2Vec2 &newOrigin)
void	Validate () const
	Validate this tree. For testing.
	~b2DynamicTree ()
	Destroy the tree, freeing the node pool.
Private Member Functions
int32	AllocateNode ()
int32	Balance (int32 index)
int32	ComputeHeight () const
int32	ComputeHeight (int32 nodeId) const
void	FreeNode (int32 node)
void	InsertLeaf (int32 node)
void	RemoveLeaf (int32 node)
void	ValidateMetrics (int32 index) const
void	ValidateStructure (int32 index) const
Private Attributes
int32	m_freeList
int32	m_insertionCount
int32	m_nodeCapacity
int32	m_nodeCount
b2TreeNode *	m_nodes
uint32	m_path
	This is used to incrementally traverse the tree for re-balancing.
int32	m_root

Detailed Description

A dynamic AABB tree broad-phase, inspired by Nathanael Presson's btDbvt. 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.

Definition at line 61 of file b2DynamicTree.h.

Constructor & Destructor Documentation

b2DynamicTree::b2DynamicTree ( )

Constructing the tree initializes the node pool.

Definition at line 22 of file b2DynamicTree.cpp.

b2DynamicTree::~b2DynamicTree ( )

Destroy the tree, freeing the node pool.

Definition at line 46 of file b2DynamicTree.cpp.

Member Function Documentation

int32 b2DynamicTree::AllocateNode ( ) [private]

Definition at line 53 of file b2DynamicTree.cpp.

int32 b2DynamicTree::Balance ( int32 index ) [private]

Definition at line 377 of file b2DynamicTree.cpp.

int32 b2DynamicTree::ComputeHeight ( ) const [private]

Definition at line 573 of file b2DynamicTree.cpp.

int32 b2DynamicTree::ComputeHeight ( int32 nodeId ) const [private]

Definition at line 558 of file b2DynamicTree.cpp.

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

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

Definition at line 105 of file b2DynamicTree.cpp.

void b2DynamicTree::DestroyProxy ( int32 proxyId )

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

Definition at line 121 of file b2DynamicTree.cpp.

void b2DynamicTree::FreeNode ( int32 node ) [private]

Definition at line 92 of file b2DynamicTree.cpp.

float32 b2DynamicTree::GetAreaRatio ( ) const

Get the ratio of the sum of the node areas to the root area.

Definition at line 531 of file b2DynamicTree.cpp.

const b2AABB & b2DynamicTree::GetFatAABB ( int32 proxyId ) const [inline]

Get the fat AABB for a proxy.

Definition at line 162 of file b2DynamicTree.h.

int32 b2DynamicTree::GetHeight ( ) const

Compute the height of the binary tree in O(N) time. Should not be called often.

Definition at line 520 of file b2DynamicTree.cpp.

int32 b2DynamicTree::GetMaxBalance ( ) const

Get the maximum balance of an node in the tree. The balance is the difference in height of the two children of a node.

Definition at line 672 of file b2DynamicTree.cpp.

void * b2DynamicTree::GetUserData ( int32 proxyId ) const [inline]

Get proxy user data.

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

Definition at line 156 of file b2DynamicTree.h.

void b2DynamicTree::InsertLeaf ( int32 node ) [private]

Definition at line 176 of file b2DynamicTree.cpp.

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.

Definition at line 130 of file b2DynamicTree.cpp.

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.

Definition at line 169 of file b2DynamicTree.h.

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.

Definition at line 204 of file b2DynamicTree.h.

void b2DynamicTree::RebuildBottomUp ( )

Build an optimal tree. Very expensive. For testing.

Definition at line 694 of file b2DynamicTree.cpp.

void b2DynamicTree::RemoveLeaf ( int32 node ) [private]

Definition at line 316 of file b2DynamicTree.cpp.

void b2DynamicTree::ShiftOrigin ( const b2Vec2 & newOrigin )

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

Parameters:

newOrigin the new origin with respect to the old origin

Definition at line 770 of file b2DynamicTree.cpp.

void b2DynamicTree::Validate ( ) const