Assimp::SpatialSort Class Reference

A little helper class to quickly find all vertices in the epsilon environment of a given position. More...

#include <SpatialSort.h>

Classes
struct	Entry
	An entry in a spatially sorted position array. More...

Public Member Functions
void	Append (const aiVector3D *pPositions, unsigned int pNumPositions, unsigned int pElementOffset, bool pFinalize=true)
	Same as Fill(), except the method appends to existing data in the SpatialSort. More...
void	Fill (const aiVector3D *pPositions, unsigned int pNumPositions, unsigned int pElementOffset, bool pFinalize=true)
	Sets the input data for the SpatialSort. More...
void	Finalize ()
	Finalize the spatial hash data structure. More...
void	FindIdenticalPositions (const aiVector3D &pPosition, std::vector< unsigned int > &poResults) const
	Fills an array with indices of all positions identical to the given position. More...
void	FindPositions (const aiVector3D &pPosition, ai_real pRadius, std::vector< unsigned int > &poResults) const
	Returns an iterator for all positions close to the given position. More...
unsigned int	GenerateMappingTable (std::vector< unsigned int > &fill, ai_real pRadius) const
	Compute a table that maps each vertex ID referring to a spatially close enough position to the same output ID. More...
	SpatialSort ()
	SpatialSort (const aiVector3D *pPositions, unsigned int pNumPositions, unsigned int pElementOffset)
	Constructs a spatially sorted representation from the given position array. More...
	~SpatialSort ()
	Destructor. More...

Protected Member Functions
ai_real	CalculateDistance (const aiVector3D &pPosition) const
	Return the distance to the sorting plane. More...

Protected Attributes
aiVector3D	mCentroid
	The centroid of the positions, which is used as a point on the sorting plane when calculating distance. More...
bool	mFinalized
	false until the Finalize method is called. More...
aiVector3D	mPlaneNormal
	Normal of the sorting plane, normalized. More...
std::vector< Entry >	mPositions

Detailed Description

A little helper class to quickly find all vertices in the epsilon environment of a given position.

Construct an instance with an array of positions. The class stores the given positions by their indices and sorts them by their distance to an arbitrary chosen plane. You can then query the instance for all vertices close to a given position in an average O(log n) time, with O(n) worst case complexity when all vertices lay on the plane. The plane is chosen so that it avoids common planes in usual data sets.

Constructor & Destructor Documentation

SpatialSort() [1/2]

Assimp::SpatialSort::SpatialSort

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SpatialSort() [2/2]

Assimp::SpatialSort::SpatialSort	(	const aiVector3D *	pPositions,
		unsigned int	pNumPositions,
		unsigned int	pElementOffset
	)

Constructs a spatially sorted representation from the given position array.

Supply the positions in its layout in memory, the class will only refer to them by index.

Parameters

pPositions	Pointer to the first position vector of the array.
pNumPositions	Number of vectors to expect in that array.
pElementOffset	Offset in bytes from the beginning of one vector in memory to the beginning of the next vector.

~SpatialSort()

Assimp::SpatialSort::~SpatialSort

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)

Destructor.

Member Function Documentation

Append()

void Assimp::SpatialSort::Append	(	const aiVector3D *	pPositions,
		unsigned int	pNumPositions,
		unsigned int	pElementOffset,
		bool	pFinalize = true
	)

Same as Fill(), except the method appends to existing data in the SpatialSort.

CalculateDistance()

ai_real Assimp::SpatialSort::CalculateDistance ( const aiVector3D &  pPosition ) const

protected

Return the distance to the sorting plane.

Fill()

void Assimp::SpatialSort::Fill	(	const aiVector3D *	pPositions,
		unsigned int	pNumPositions,
		unsigned int	pElementOffset,
		bool	pFinalize = true
	)

Sets the input data for the SpatialSort.

This replaces existing data, if any. The new data receives new indices in ascending order.

Parameters

pPositions	Pointer to the first position vector of the array.
pNumPositions	Number of vectors to expect in that array.
pElementOffset	Offset in bytes from the beginning of one vector in memory to the beginning of the next vector.
pFinalize	Specifies whether the SpatialSort's internal representation is finalized after the new data has been added. Finalization is required in order to use #FindPosition() or GenerateMappingTable(). If you don't finalize yet, you can use Append() to add data from other sources.

Finalize()

void Assimp::SpatialSort::Finalize

(

)

Finalize the spatial hash data structure.

This can be useful after multiple calls to Append() with the pFinalize parameter set to false. This is finally required before one of FindPositions() and GenerateMappingTable() can be called to query the spatial sort.

FindIdenticalPositions()

void Assimp::SpatialSort::FindIdenticalPositions	(	const aiVector3D &	pPosition,
		std::vector< unsigned int > &	poResults
	)		const

Fills an array with indices of all positions identical to the given position.

In opposite to FindPositions(), not an epsilon is used but a (very low) tolerance of four floating-point units.

Parameters

pPosition	The position to look for vertices.
poResults	The container to store the indices of the found positions. Will be emptied by the call so it may contain anything.

FindPositions()

void Assimp::SpatialSort::FindPositions	(	const aiVector3D &	pPosition,
		ai_real	pRadius,
		std::vector< unsigned int > &	poResults
	)		const

Returns an iterator for all positions close to the given position.

Parameters

pPosition	The position to look for vertices.
pRadius	Maximal distance from the position a vertex may have to be counted in.
poResults	The container to store the indices of the found positions. Will be emptied by the call so it may contain anything.

Returns

An iterator to iterate over all vertices in the given area.

GenerateMappingTable()

unsigned int Assimp::SpatialSort::GenerateMappingTable	(	std::vector< unsigned int > &	fill,
		ai_real	pRadius
	)		const

Compute a table that maps each vertex ID referring to a spatially close enough position to the same output ID.

Output IDs are assigned in ascending order from 0...n.

Parameters

fill	Will be filled with numPositions entries.
pRadius	Maximal distance from the position a vertex may have to be counted in.

Returns

Number of unique vertices (n).

Member Data Documentation

mCentroid

aiVector3D Assimp::SpatialSort::mCentroid

protected

The centroid of the positions, which is used as a point on the sorting plane when calculating distance.

This value is calculated in Finalize.

mFinalized

bool Assimp::SpatialSort::mFinalized

protected

false until the Finalize method is called.

mPlaneNormal

aiVector3D Assimp::SpatialSort::mPlaneNormal

protected

Normal of the sorting plane, normalized.

mPositions

std::vector<Entry> Assimp::SpatialSort::mPositions

protected

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

• SpatialSort.h