Generate axis aligned BBox tree for raycasting and other Locator based searches. More...

#include <vtkModifiedBSPTree.h>

Inheritance diagram for vtkModifiedBSPTree:

Collaboration diagram for vtkModifiedBSPTree:

Public Member Functions
void	FreeSearchStructure ()

void	BuildLocator ()

virtual void	GenerateRepresentation (int level, vtkPolyData *pd)

virtual void	GenerateRepresentationLeafs (vtkPolyData *pd)

bool	InsideCellBounds (double x[3], vtkIdType cell_ID)

vtkIdListCollection *	GetLeafNodeCellInformation ()


virtual int	IntersectWithLine (double p1[3], double p2[3], double tol, double &t, double x[3], double pcoords[3], int &subId, vtkIdType &cellId)


virtual int	IntersectWithLine (double p1[3], double p2[3], double tol, double &t, double x[3], double pcoords[3], int &subId, vtkIdType &cellId, vtkGenericCell *cell)


virtual int	IntersectWithLine (const double p1[3], const double p2[3], const double tol, vtkPoints points, vtkIdList cellIds)


virtual vtkIdType	FindCell (double x[3], double tol2, vtkGenericCell GenCell, double pcoords[3], double weights)

Public Member Functions inherited from vtkAbstractCellLocator
vtkAbstractCellLocator *	NewInstance () const

virtual void	FindCellsWithinBounds (double bbox, vtkIdList cells)

virtual vtkIdType	FindCell (double x[3])

virtual void	SetNumberOfCellsPerNode (int)

virtual int	GetNumberOfCellsPerNode ()

virtual void	SetCacheCellBounds (int)

virtual int	GetCacheCellBounds ()

virtual void	CacheCellBoundsOn ()

virtual void	CacheCellBoundsOff ()

virtual void	SetRetainCellLists (int)

virtual int	GetRetainCellLists ()

virtual void	RetainCellListsOn ()

virtual void	RetainCellListsOff ()

virtual void	SetLazyEvaluation (int)

virtual int	GetLazyEvaluation ()

virtual void	LazyEvaluationOn ()

virtual void	LazyEvaluationOff ()

virtual void	SetUseExistingSearchStructure (int)

virtual int	GetUseExistingSearchStructure ()

virtual void	UseExistingSearchStructureOn ()

virtual void	UseExistingSearchStructureOff ()

virtual int	IntersectWithLine (double p1[3], double p2[3], double tol, double &t, double x[3], double pcoords[3], int &subId)

virtual int	IntersectWithLine (const double p1[3], const double p2[3], vtkPoints points, vtkIdList cellIds)

virtual void	FindClosestPoint (double x[3], double closestPoint[3], vtkIdType &cellId, int &subId, double &dist2)

virtual void	FindClosestPoint (double x[3], double closestPoint[3], vtkGenericCell *cell, vtkIdType &cellId, int &subId, double &dist2)

virtual vtkIdType	FindClosestPointWithinRadius (double x[3], double radius, double closestPoint[3], vtkIdType &cellId, int &subId, double &dist2)

virtual vtkIdType	FindClosestPointWithinRadius (double x[3], double radius, double closestPoint[3], vtkGenericCell *cell, vtkIdType &cellId, int &subId, double &dist2)

virtual vtkIdType	FindClosestPointWithinRadius (double x[3], double radius, double closestPoint[3], vtkGenericCell *cell, vtkIdType &cellId, int &subId, double &dist2, int &inside)

virtual void	FindCellsAlongLine (double p1[3], double p2[3], double tolerance, vtkIdList *cells)

Public Member Functions inherited from vtkLocator
vtkLocator *	NewInstance () const

virtual void	Update ()

virtual void	Initialize ()

virtual void	SetDataSet (vtkDataSet *)

virtual vtkDataSet *	GetDataSet ()

virtual void	SetMaxLevel (int)

virtual int	GetMaxLevel ()

virtual int	GetLevel ()

virtual void	SetAutomatic (int)

virtual int	GetAutomatic ()

virtual void	AutomaticOn ()

virtual void	AutomaticOff ()

virtual void	SetTolerance (double)

virtual double	GetTolerance ()

virtual unsigned long	GetBuildTime ()

virtual void	Register (vtkObjectBase *o)

virtual void	UnRegister (vtkObjectBase *o)

Public Member Functions inherited from vtkObject
vtkObject *	NewInstance () const

virtual void	DebugOn ()

virtual void	DebugOff ()

bool	GetDebug ()

void	SetDebug (bool debugFlag)

virtual void	Modified ()

virtual unsigned long	GetMTime ()

unsigned long	AddObserver (unsigned long event, vtkCommand *, float priority=0.0f)

unsigned long	AddObserver (const char event, vtkCommand , float priority=0.0f)

vtkCommand *	GetCommand (unsigned long tag)

void	RemoveObserver (vtkCommand *)

void	RemoveObservers (unsigned long event, vtkCommand *)

void	RemoveObservers (const char event, vtkCommand )

int	HasObserver (unsigned long event, vtkCommand *)

int	HasObserver (const char event, vtkCommand )

void	RemoveObserver (unsigned long tag)

void	RemoveObservers (unsigned long event)

void	RemoveObservers (const char *event)

void	RemoveAllObservers ()

int	HasObserver (unsigned long event)

int	HasObserver (const char *event)

template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, void(T::*callback)(), float priority=0.0f)

template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, void(T::callback)(vtkObject , unsigned long, void *), float priority=0.0f)

template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, bool(T::callback)(vtkObject , unsigned long, void *), float priority=0.0f)

int	InvokeEvent (unsigned long event, void *callData)

int	InvokeEvent (const char event, void callData)

int	InvokeEvent (unsigned long event)

int	InvokeEvent (const char *event)

Public Member Functions inherited from vtkObjectBase
const char *	GetClassName () const

virtual void	Delete ()

virtual void	FastDelete ()

void	Print (ostream &os)

void	SetReferenceCount (int)

void	PrintRevisions (ostream &)

virtual void	PrintHeader (ostream &os, vtkIndent indent)

virtual void	PrintTrailer (ostream &os, vtkIndent indent)

int	GetReferenceCount ()

Static Public Member Functions
static vtkModifiedBSPTree *	New ()

Static Public Member Functions inherited from vtkAbstractCellLocator
static int	IsTypeOf (const char *type)

static vtkAbstractCellLocator *	SafeDownCast (vtkObjectBase *o)

Static Public Member Functions inherited from vtkLocator
static int	IsTypeOf (const char *type)

static vtkLocator *	SafeDownCast (vtkObjectBase *o)

Static Public Member Functions inherited from vtkObject
static int	IsTypeOf (const char *type)

static vtkObject *	SafeDownCast (vtkObjectBase *o)

static vtkObject *	New ()

static void	BreakOnError ()

static void	SetGlobalWarningDisplay (int val)

static void	GlobalWarningDisplayOn ()

static void	GlobalWarningDisplayOff ()

static int	GetGlobalWarningDisplay ()

Static Public Member Functions inherited from vtkObjectBase
static int	IsTypeOf (const char *name)

static vtkObjectBase *	New ()

Protected Member Functions
	vtkModifiedBSPTree ()

	~vtkModifiedBSPTree ()

void	Subdivide (BSPNode node, Sorted_cell_extents_Lists lists, vtkDataSet *dataSet, vtkIdType nCells, int depth, int maxlevel, vtkIdType maxCells, int &MaxDepth)

virtual int	IntersectCellInternal (vtkIdType cell_ID, const double p1[3], const double p2[3], const double tol, double &t, double ipt[3], double pcoords[3], int &subId)

void	BuildLocatorIfNeeded ()

void	ForceBuildLocator ()

void	BuildLocatorInternal ()

Protected Member Functions inherited from vtkAbstractCellLocator
	vtkAbstractCellLocator ()

	~vtkAbstractCellLocator ()

virtual bool	StoreCellBounds ()

virtual void	FreeCellBounds ()

Protected Member Functions inherited from vtkLocator
virtual void	ReportReferences (vtkGarbageCollector *)

	vtkLocator ()

	~vtkLocator ()

Protected Member Functions inherited from vtkObject
	vtkObject ()

virtual	~vtkObject ()

virtual void	RegisterInternal (vtkObjectBase *, int check)

virtual void	UnRegisterInternal (vtkObjectBase *, int check)

void	InternalGrabFocus (vtkCommand mouseEvents, vtkCommand keypressEvents=NULL)

void	InternalReleaseFocus ()

Protected Member Functions inherited from vtkObjectBase
	vtkObjectBase ()

virtual	~vtkObjectBase ()

virtual void	CollectRevisions (ostream &)

	vtkObjectBase (const vtkObjectBase &)

void	operator= (const vtkObjectBase &)

Protected Attributes
BSPNode *	mRoot

int	npn

int	nln

int	tot_depth

Protected Attributes inherited from vtkAbstractCellLocator
int	NumberOfCellsPerNode

int	RetainCellLists

int	CacheCellBounds

int	LazyEvaluation

int	UseExistingSearchStructure

vtkGenericCell *	GenericCell

double(*	CellBounds )[6]

Protected Attributes inherited from vtkLocator
vtkDataSet *	DataSet

int	Automatic

double	Tolerance

int	MaxLevel

int	Level

vtkTimeStamp	BuildTime

Protected Attributes inherited from vtkObject
bool	Debug

vtkTimeStamp	MTime

vtkSubjectHelper *	SubjectHelper

Protected Attributes inherited from vtkObjectBase
vtkAtomicInt32	ReferenceCount

vtkWeakPointerBase **	WeakPointers

typedef vtkAbstractCellLocator	Superclass

static int	IsTypeOf (const char *type)

static vtkModifiedBSPTree *	SafeDownCast (vtkObjectBase *o)

virtual int	IsA (const char *type)

vtkModifiedBSPTree *	NewInstance () const

void	PrintSelf (ostream &os, vtkIndent indent)

virtual vtkObjectBase *	NewInstanceInternal () const

Additional Inherited Members
Public Types inherited from vtkAbstractCellLocator
typedef vtkLocator	Superclass

Public Types inherited from vtkLocator
typedef vtkObject	Superclass

Public Types inherited from vtkObject
typedef vtkObjectBase	Superclass

Detailed Description

Generate axis aligned BBox tree for raycasting and other Locator based searches.

vtkModifiedBSPTree creates an evenly balanced BSP tree using a top down implementation. Axis aligned split planes are found which evenly divide cells into two buckets. Generally a split plane will intersect some cells and these are usually stored in both child nodes of the current parent. (Or split into separate cells which we cannot consider in this case). Storing cells in multiple buckets creates problems associated with multiple tests against rays and increases the required storage as complex meshes will have many cells straddling a split plane (and further splits may cause multiple copies of these).

During a discussion with Arno Formella in 1998 he suggested using a third child node to store objects which straddle split planes. I've not seen this published (Yes! - see below), but thought it worth trying. This implementation of the BSP tree creates a third child node for storing cells laying across split planes, the third cell may overlap the other two, but the two 'proper' nodes otherwise conform to usual BSP rules.

The advantage of this implementation is cells only ever lie in one node and mailbox testing is avoided. All BBoxes are axis aligned and a ray cast uses an efficient search strategy based on near/far nodes and rejects all BBoxes using simple tests.

For fast raytracing, 6 copies of cell lists are stored in each leaf node each list is in axis sorted order +/- x,y,z and cells are always tested in the direction of the ray dominant axis. Once an intersection is found any cell or BBox with a closest point further than the I-point can be instantly rejected and raytracing stops as soon as no nodes can be closer than the current best intersection point.

The addition of the 'middle' node upsets the optimal balance of the tree, but is a minor overhead during the raytrace. Each child node is contracted such that it tightly fits all cells inside it, enabling further ray/box rejections.

This class is intended for persons requiring many ray tests and is optimized for this purpose. As no cell ever lies in more than one leaf node, and parent nodes do not maintain cell lists, the memory overhead of the sorted cell lists is 6*num_cells*4 for 6 lists of ints, each num_cells in length. The memory requirement of the nodes themselves is usually of minor significance.

Subdividision is controlled by MaxCellsPerNode - any node with more than this number will be subdivided providing a good split plane can be found and the max depth is not exceeded.

The average cells per leaf will usually be around half the MaxCellsPerNode, though the middle node is usually sparsely populated and lowers the average slightly. The middle node will not be created when not needed. Subdividing down to very small cells per node is not generally suggested as then the 6 stored cell lists are effectively redundant.

Values of MaxcellsPerNode of around 16->128 depending on dataset size will usually give good results.

Cells are only sorted into 6 lists once - before tree creation, each node segments the lists and passes them down to the new child nodes whilst maintaining sorted order. This makes for an efficient subdivision strategy.

NB. The following reference has been sent to me {formella-1995-ray, author = "Arno Formella and Christian Gill", title = "{Ray Tracing: A Quantitative Analysis and a New Practical Algorithm}", journal = "{The Visual Computer}", year = "{1995}", month = dec, pages = "{465--476}", volume = "{11}", number = "{9}", publisher = "{Springer}", keywords = "{ray tracing, space subdivision, plane traversal, octree, clustering, benchmark scenes}", annote = "{We present a new method to accelerate the process of finding nearest ray–object intersections in ray tracing. The algorithm consumes an amount of memory more or less linear in the number of objects. The basic ideas can be characterized with a modified BSP–tree and plane traversal. Plane traversal is a fast linear time algorithm to find the closest intersection point in a list of bounding volumes hit by a ray. We use plane traversal at every node of the high outdegree BSP–tree. Our implementation is competitive to fast ray tracing programs. We present a benchmark suite which allows for an extensive comparison of ray tracing algorithms.}", }

Thanks:: John Biddiscombe for developing and contributing this class

Todo:: Implement intersection heap for testing rays against transparent objects

Style:

This class is currently maintained by J. Biddiscombe who has specially requested that the code style not be modified to the kitware standard. Please respect the contribution of this class by keeping the style as close as possible to the author's original.

Tests:: vtkModifiedBSPTree (Tests)

Definition at line 160 of file vtkModifiedBSPTree.h.

Member Typedef Documentation

typedef vtkAbstractCellLocator vtkModifiedBSPTree::Superclass

Standard Type-Macro

Definition at line 164 of file vtkModifiedBSPTree.h.

Constructor & Destructor Documentation

vtkModifiedBSPTree::vtkModifiedBSPTree ( )

protected

vtkModifiedBSPTree::~vtkModifiedBSPTree ( )

protected

Member Function Documentation

static int vtkModifiedBSPTree::IsTypeOf ( const char * type )

static

Standard Type-Macro

virtual int vtkModifiedBSPTree::IsA ( const char * type )

virtual

Standard Type-Macro

Reimplemented from vtkAbstractCellLocator.

static vtkModifiedBSPTree* vtkModifiedBSPTree::SafeDownCast ( vtkObjectBase * o )

static

Standard Type-Macro

virtual vtkObjectBase* vtkModifiedBSPTree::NewInstanceInternal ( ) const

protectedvirtual

Standard Type-Macro

Reimplemented from vtkAbstractCellLocator.

vtkModifiedBSPTree* vtkModifiedBSPTree::NewInstance ( ) const

Standard Type-Macro

void vtkModifiedBSPTree::PrintSelf	(	ostream &	os,
		vtkIndent	indent
	)

virtual

Standard Type-Macro

Reimplemented from vtkAbstractCellLocator.

static vtkModifiedBSPTree* vtkModifiedBSPTree::New ( )

static

Construct with maximum 32 cells per node. (average 16->31)

void vtkModifiedBSPTree::FreeSearchStructure ( )

virtual

Free tree memory

Implements vtkLocator.

void vtkModifiedBSPTree::BuildLocator ( )

virtual

Build Tree

Implements vtkLocator.

virtual void vtkModifiedBSPTree::GenerateRepresentation	(	int	level,
		vtkPolyData *	pd
	)

virtual

Generate BBox representation of Nth level

Implements vtkLocator.

virtual void vtkModifiedBSPTree::GenerateRepresentationLeafs ( vtkPolyData * pd )

virtual

Generate BBox representation of all leaf nodes

virtual int vtkModifiedBSPTree::IntersectWithLine	(	double	p1[3],
		double	p2[3],
		double	tol,
		double &	t,
		double	x[3],
		double	pcoords[3],
		int &	subId,
		vtkIdType &	cellId
	)

virtual

Return intersection point (if any) AND the cell which was intersected by the finite line. Uses fast tree-search BBox rejection tests.

Reimplemented from vtkAbstractCellLocator.

virtual int vtkModifiedBSPTree::IntersectWithLine	(	double	p1[3],
		double	p2[3],
		double	tol,
		double &	t,
		double	x[3],
		double	pcoords[3],
		int &	subId,
		vtkIdType &	cellId,
		vtkGenericCell *	cell
	)

virtual

Return intersection point (if any) AND the cell which was intersected by the finite line. The cell is returned as a cell id and as a generic cell.

Reimplemented from vtkAbstractCellLocator.

virtual int vtkModifiedBSPTree::IntersectWithLine	(	const double	p1[3],
		const double	p2[3],
		const double	tol,
		vtkPoints *	points,
		vtkIdList *	cellIds
	)

virtual

Take the passed line segment and intersect it with the data set. The return value of the function is 0 if no intersections were found. For each intersection found, the vtkPoints and CellIds objects have the relevant information added in order of intersection increasing from ray start to end. If either vtkPoints or CellIds are NULL pointers, then no information is generated for that list.

virtual vtkIdType vtkModifiedBSPTree::FindCell	(	double	x[3],
		double	tol2,
		vtkGenericCell *	GenCell,
		double	pcoords[3],
		double *	weights
	)

virtual

Test a point to find if it is inside a cell. Returns the cellId if inside or -1 if not.

Reimplemented from vtkAbstractCellLocator.

bool vtkModifiedBSPTree::InsideCellBounds	(	double	x[3],
		vtkIdType	cell_ID
	)

virtual

Quickly test if a point is inside the bounds of a particular cell. Some locators cache cell bounds and this function can make use of fast access to the data.

Reimplemented from vtkAbstractCellLocator.

vtkIdListCollection* vtkModifiedBSPTree::GetLeafNodeCellInformation ( )

After subdivision has completed, one may wish to query the tree to find which cells are in which leaf nodes. This function returns a list which holds a cell Id list for each leaf node.

void vtkModifiedBSPTree::Subdivide	(	BSPNode *	node,
		Sorted_cell_extents_Lists *	lists,
		vtkDataSet *	dataSet,
		vtkIdType	nCells,
		int	depth,
		int	maxlevel,
		vtkIdType	maxCells,
		int &	MaxDepth
	)

protected

virtual int vtkModifiedBSPTree::IntersectCellInternal	(	vtkIdType	cell_ID,
		const double	p1[3],
		const double	p2[3],
		const double	tol,
		double &	t,
		double	ipt[3],
		double	pcoords[3],
		int &	subId
	)

protectedvirtual

void vtkModifiedBSPTree::BuildLocatorIfNeeded ( )

protected

void vtkModifiedBSPTree::ForceBuildLocator ( )

protected

void vtkModifiedBSPTree::BuildLocatorInternal ( )

protected

Member Data Documentation

BSPNode* vtkModifiedBSPTree::mRoot

protected

Definition at line 236 of file vtkModifiedBSPTree.h.

int vtkModifiedBSPTree::npn

protected

Definition at line 237 of file vtkModifiedBSPTree.h.

int vtkModifiedBSPTree::nln

protected

Definition at line 238 of file vtkModifiedBSPTree.h.

int vtkModifiedBSPTree::tot_depth

protected

Definition at line 239 of file vtkModifiedBSPTree.h.

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

/home/boeckb/code/depot/group-kitware/vtk/build-release/Utilities/Doxygen/dox/Filters/FlowPaths/vtkModifiedBSPTree.h

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Style:

Member Typedef Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation