Performs fast BVH construction using LBVH building approach. Algorithm uses spatial Morton codes to reduce the BVH construction problem to a sorting problem (radix sort – O(N) complexity). This Linear Bounding Volume Hierarchy (LBVH) builder produces BVH trees of lower quality compared to SAH-based BVH builders but it is over an order of magnitude faster (up to 3M triangles per second). More...

#include <BVH_LinearBuilder.hxx>

Inheritance diagram for BVH_LinearBuilder< T, N >:

[legend]

Public Types
typedef BVH::VectorType< T, N >::Type	BVH_VecNt

Public Types inherited from Standard_Transient
typedef void	base_type
	Returns a type descriptor about this object.

Public Member Functions
	BVH_LinearBuilder (const int theLeafNodeSize=BVH_Constants_LeafNodeSizeDefault, const int theMaxTreeDepth=BVH_Constants_MaxTreeDepth)
	Creates binned LBVH builder.

	~BVH_LinearBuilder () override
	Releases resources of LBVH builder.

void	Build (BVH_Set< T, N > theSet, BVH_Tree< T, N > theBVH, const BVH_Box< T, N > &theBox) const override
	Builds BVH.

Public Member Functions inherited from BVH_BuilderTransient
int	MaxTreeDepth () const
	Returns the maximum depth of constructed BVH.

int	LeafNodeSize () const
	Returns the maximum number of sub-elements in the leaf.

bool	IsParallel () const
	Returns parallel flag.

void	SetParallel (const bool isParallel)
	Set parallel flag controlling possibility of parallel execution.

Public Member Functions inherited from Standard_Transient
	Standard_Transient ()
	Empty constructor.

	Standard_Transient (const Standard_Transient &)
	Copy constructor – does nothing.

Standard_Transient &	operator= (const Standard_Transient &)
	Assignment operator, needed to avoid copying reference counter.

virtual	~Standard_Transient ()=default
	Destructor must be virtual.

virtual const opencascade::handle< Standard_Type > &	DynamicType () const
	Returns a type descriptor about this object.

bool	IsInstance (const opencascade::handle< Standard_Type > &theType) const
	Returns a true value if this is an instance of Type.

bool	IsInstance (const char *const theTypeName) const
	Returns a true value if this is an instance of TypeName.

bool	IsKind (const opencascade::handle< Standard_Type > &theType) const
	Returns true if this is an instance of Type or an instance of any class that inherits from Type. Note that multiple inheritance is not supported by OCCT RTTI mechanism.

bool	IsKind (const char *const theTypeName) const
	Returns true if this is an instance of TypeName or an instance of any class that inherits from TypeName. Note that multiple inheritance is not supported by OCCT RTTI mechanism.

Standard_Transient *	This () const
	Returns non-const pointer to this object (like const_cast). For protection against creating handle to objects allocated in stack or call from constructor, it will raise exception Standard_ProgramError if reference counter is zero.

int	GetRefCount () const noexcept
	Get the reference counter of this object.

void	IncrementRefCounter () noexcept
	Increments the reference counter of this object. Uses relaxed memory ordering since incrementing only requires atomicity, not synchronization with other memory operations.

int	DecrementRefCounter () noexcept
	Decrements the reference counter of this object; returns the decremented value. Uses release ordering for the decrement to ensure all writes to the object are visible before the count reaches zero. An acquire fence is added only when the count reaches zero, ensuring proper synchronization before deletion. This is more efficient than using acq_rel for every decrement.

virtual void	Delete () const
	Memory deallocator for transient classes.

Protected Types
typedef NCollection_Array1< BVH_EncodedLink >::iterator	LinkIterator

Protected Member Functions
int	emitHierachy (BVH_Tree< T, N > *theBVH, const NCollection_Array1< BVH_EncodedLink > &theEncodedLinks, const int theBit, const int theShift, const int theStart, const int theFinal) const
	Emits hierarchy from sorted Morton codes.

int	lowerBound (const NCollection_Array1< BVH_EncodedLink > &theEncodedLinks, int theStart, int theFinal, int theDigit) const
	Returns index of the first element which does not compare less than the given one.

Protected Member Functions inherited from BVH_Builder< T, N >
	BVH_Builder (const int theLeafNodeSize, const int theMaxTreeDepth)
	Creates new abstract BVH builder.

void	updateDepth (BVH_Tree< T, N > *theBVH, const int theLevel) const
	Updates depth of constructed BVH tree.

Protected Member Functions inherited from BVH_BuilderTransient
	BVH_BuilderTransient (const int theLeafNodeSize, const int theMaxTreeDepth)
	Creates new abstract BVH builder.

Additional Inherited Members
Static Public Member Functions inherited from Standard_Transient
static constexpr const char *	get_type_name ()
	Returns a type descriptor about this object.

static const opencascade::handle< Standard_Type > &	get_type_descriptor ()
	Returns type descriptor of Standard_Transient class.

Protected Attributes inherited from BVH_BuilderTransient
int	myMaxTreeDepth
	Maximum depth of constructed BVH.

int	myLeafNodeSize
	Maximum number of objects per leaf.

bool	myIsParallel
	Parallel execution flag.

Detailed Description

template<class T, int N>
class BVH_LinearBuilder< T, N >

Performs fast BVH construction using LBVH building approach. Algorithm uses spatial Morton codes to reduce the BVH construction problem to a sorting problem (radix sort – O(N) complexity). This Linear Bounding Volume Hierarchy (LBVH) builder produces BVH trees of lower quality compared to SAH-based BVH builders but it is over an order of magnitude faster (up to 3M triangles per second).

For more details see: C. Lauterbach, M. Garland, S. Sengupta, D. Luebke, and D. Manocha. Fast BVH construction on GPUs. Eurographics, 2009.

Member Typedef Documentation

◆ BVH_VecNt

template<class T , int N>

typedef BVH::VectorType<T,N>::Type BVH_LinearBuilder< T, N >::BVH_VecNt

◆ LinkIterator

template<class T , int N>

typedef NCollection_Array1<BVH_EncodedLink>::iterator BVH_LinearBuilder< T, N >::LinkIterator

protected

Constructor & Destructor Documentation

◆ BVH_LinearBuilder()

template<class T , int N>

BVH_LinearBuilder< T, N >::BVH_LinearBuilder	(	const int	theLeafNodeSize = BVH_Constants_LeafNodeSizeDefault,
		const int	theMaxTreeDepth = BVH_Constants_MaxTreeDepth )

Creates binned LBVH builder.

◆ ~BVH_LinearBuilder()

template<class T , int N>

BVH_LinearBuilder< T, N >::~BVH_LinearBuilder ( )

overridedefault

Releases resources of LBVH builder.

Member Function Documentation

◆ Build()

template<class T , int N>

void BVH_LinearBuilder< T, N >::Build	(	BVH_Set< T, N > *	theSet,
		BVH_Tree< T, N > *	theBVH,
		const BVH_Box< T, N > &	theBox ) const

overridevirtual

Builds BVH.

Implements BVH_Builder< T, N >.

◆ emitHierachy()

template<class T , int N>

int BVH_LinearBuilder< T, N >::emitHierachy	(	BVH_Tree< T, N > *	theBVH,
		const NCollection_Array1< BVH_EncodedLink > &	theEncodedLinks,
		const int	theBit,
		const int	theShift,
		const int	theStart,
		const int	theFinal ) const

protected

Emits hierarchy from sorted Morton codes.

◆ lowerBound()

template<class T , int N>

int BVH_LinearBuilder< T, N >::lowerBound	(	const NCollection_Array1< BVH_EncodedLink > &	theEncodedLinks,
		int	theStart,
		int	theFinal,
		int	theDigit ) const

protected

Returns index of the first element which does not compare less than the given one.

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

BVH_LinearBuilder.hxx

Public Types

Public Member Functions

Protected Types

Protected Member Functions

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ BVH_VecNt

◆ LinkIterator

Constructor & Destructor Documentation

◆ BVH_LinearBuilder()

◆ ~BVH_LinearBuilder()

Member Function Documentation

◆ Build()

◆ emitHierachy()

◆ lowerBound()