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/*=========================================================================
Program: Visualization Toolkit
Module: vtkStaticEdgeLocatorTemplate.h
Copyright (c) Kitware, Inc.
All rights reserved.
See LICENSE file for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
/**
* @class vtkStaticEdgeLocatorTemplate
* @brief templated locator for managing edges and associated data on edges
*
*
* vtkStaticEdgeLocatorTemplate provides methods for ordering and tracking
* edges, as well as associating data with edges. (An edge is a tuple (v0,v1)
* with v0 < v1.) Typically this class may be used for isocontouring or any
* operation that operates on edges and needs to determine whether duplicates
* exist. The class is templated on 1) the type used to represent the id
* tuple; and 2) the data associated with the edge.
*
* This class is non-incremental (i.e., static). That is, an array of edges
* is provided and the locator is built from this array. Incremental
* additions of new edges is not allowed (analogoues to vtkStaticPointLocator
* and vtkStaticCellLocator).
*
* Finally, there are two distinct usage patterns for this class. One is to
* inject edges and then later search for them. This pattern begins with
* BuildLocator() and then is followed by repeated calls to IsInsertedEdge().
* Internally this operates on an array of EdgeTupleType. The second pattern
* operates on an array of MergeTupleType. It simply sorts the array using
* MergeEdges(), thereby grouping identical edges. An offset array is created
* that refers to the beginning of each group, hence indirectly indicating
* the number of unique edges, and providing O(1) access to each edge.
*
* @warning
* The id tuple type can be specified via templating to reduce memory and
* speed processing.
*
* @warning
* By default, a parametric coordinate T is associated with edges. By using
* the appropriate template parameter it is possible to associate other data
* with each edge. Note however that this data is not used when comparing and
* sorting the edges. (This could be changed - define appropriate comparison
* operators.)
*
* @warning
* This class has been threaded with vtkSMPTools. Using TBB or other
* non-sequential type (set in the CMake variable
* VTK_SMP_IMPLEMENTATION_TYPE) may improve performance significantly.
*
* @sa
* vtkEdgeTable vtkStaticPointLocator vtkStaticCellLocator
*/
#ifndef vtkStaticEdgeLocatorTemplate_h
#define vtkStaticEdgeLocatorTemplate_h
#include <algorithm>
#include <vector>
/**
* Definition of an edge tuple. Note that the TId template type may be
* specified to manage memory resources, and provide increased speeds (e.g.,
* sort) by using smaller types (32-int versus 64-bit vtkIdType). It is
* required that V0 < V1; the tuple constructor enforces this.
*/
template <typename TId, typename TED>
struct EdgeTuple
{
TId V0;
TId V1;
TED T;
// Default constructor - nothing needs to be done
EdgeTuple() {}
// Construct an edge and ensure that the edge tuple (vo,v1) is
// specified such that (v0<v1).
EdgeTuple(TId v0, TId v1, TED data)
: V0(v0)
, V1(v1)
, T(data)
{
if (this->V0 > this->V1)
{
TId tmp = this->V0;
this->V0 = this->V1;
this->V1 = tmp;
}
}
bool operator==(const EdgeTuple& et) const
{
return ((this->V0 == et.V0 && this->V1 == et.V1) ? true : false);
}
bool IsEdge(TId v0, TId v1) const
{
if (v0 < v1) // ordered properly
{
return ((this->V0 == v0 && this->V1 == v1) ? true : false);
}
else // swap comparison required
{
return ((this->V0 == v1 && this->V1 == v0) ? true : false);
}
}
// Sort on v0 first, then v1.
bool operator<(const EdgeTuple& tup) const
{
if (this->V0 < tup.V0)
return true;
if (tup.V0 < this->V0)
return false;
if (this->V1 < tup.V1)
return true;
return false;
}
};
/**
* Definition of an edge tuple using for creating an edge merge table. Note
* that the TId template type may be specified to manage memory resources,
* and provide increased speeds (e.g., sort) by using smaller types (32-int
* versus 64-bit vtkIdType). It is required that V0 < V1.
*/
template <typename TId, typename TED>
struct MergeTuple
{
TId V0;
TId V1;
TId EId; // originating edge id
TED T;
// Default constructor - nothing needs to be done
MergeTuple() {}
// Construct an edge and ensure that the edge tuple (vo,v1) is
// specified such that (v0<v1).
MergeTuple(TId v0, TId v1, TId eid, TED data)
: V0(v0)
, V1(v1)
, EId(eid)
, T(data)
{
if (this->V0 > this->V1)
{
TId tmp = this->V0;
this->V0 = this->V1;
this->V1 = tmp;
}
}
bool operator==(const MergeTuple& et) const
{
return ((this->V0 == et.V0 && this->V1 == et.V1) ? true : false);
}
bool operator!=(const MergeTuple& et) const
{
return ((this->V0 != et.V0 || this->V1 != et.V1) ? true : false);
}
// Sort on v0 first, then v1.
bool operator<(const MergeTuple& tup) const
{
if (this->V0 < tup.V0)
return true;
if (tup.V0 < this->V0)
return false;
if (this->V1 < tup.V1)
return true;
return false;
}
};
/**
* Templated on types of ids defining an edge, and any data associated with
* the edge.
*/
template <typename IDType, typename EdgeData>
class vtkStaticEdgeLocatorTemplate
{
public:
//@{
/**
* Some convenient typedefs.
*/
typedef EdgeTuple<IDType, EdgeData> EdgeTupleType;
typedef MergeTuple<IDType, EdgeData> MergeTupleType;
//@)
/**
* Construct an empty edge locator.
*/
vtkStaticEdgeLocatorTemplate()
: NumEdges(0)
, NumEdgesPerBin(5)
, EdgeArray(nullptr)
, EdgeOffsets(nullptr)
, MinV0(0)
, MaxV0(0)
, V0Range(0)
, NDivs(0)
, MergeArray(nullptr)
{
}
/**
* Delete internal offset array. The edgeArray is provided from outside the
* class and so not deleted.
*/
~vtkStaticEdgeLocatorTemplate() { delete[] this->EdgeOffsets; }
/**
* Return the number of edges in the edge array.
*/
IDType GetNumberOfEdges() { return this->NumEdges; }
/**
* This method sorts (in place) an array of MergeTupleType (of length
* numEdges) into separate groups, and allocates and returns an offset
* array providing access to each group. Each grouping is a list of
* duplicate edges. The method indicates the number of unique edges
* numUniqueEdges. Note that the offset array end value
* offsets[numUniqueEdges] = numEdges, i.e., total allocation of the
* offsets array is numUniqueEdges+1. Also note that the EId contained in
* the sorted MergeTuples can be used to renumber edges from initial ids
* (possibly one of several duplicates) to unique edge ids.
*/
const IDType* MergeEdges(
vtkIdType numEdges, MergeTupleType* edgeArray, vtkIdType& numUniqueEdges);
/**
* This method constructs the edge locator to be used when searching for
* edges. Basically it does a sort of the provided numEdges edges (which
* likely contains duplicates), and builds an offset table to provide rapid
* access to edge (v0,v1). The sort is performed via a parallel
* vtkSMPTools::Sort(). The provided array is modified in place. The
* method returns the number of unique edges.
*/
vtkIdType BuildLocator(vtkIdType numEdges, EdgeTupleType* edgeArray);
/**
* Return the id of the edge indicated. If the edge has not been inserted
* return <0. Note that the vertices (v0,v1) do not have to be in any
* particular (ascending/descending) order. BuildLocator() should be called
* prior to using this method.
*/
IDType IsInsertedEdge(IDType v0, IDType v1) const
{
// Ensure that data is consistent with what is expected.
IDType V0, V1;
if (v0 < v1)
{
V0 = v0;
V1 = v1;
}
else
{
V0 = v1;
V1 = v0;
}
if (V0 < this->MinV0 || V0 > this->MaxV0)
{
return -1;
}
// Bin and search for matching edge
IDType curBin = this->HashBin(V0);
IDType curId = this->EdgeOffsets[curBin];
IDType curV0 = this->EdgeArray[curId].V0;
IDType num = this->GetNumberOfEdgesInBin(curBin);
for (IDType i = 0; i < num; ++i)
{
while (curV0 < V0)
{
curId++;
curV0 = this->EdgeArray[curId].V0;
}
if (curV0 > V0)
{
return -1;
}
else // matched v0, now find v1
{
IDType curV1 = this->EdgeArray[curId].V1;
while (curV1 < V1)
{
curId++;
curV1 = this->EdgeArray[curId].V1;
}
if (curV1 > V1)
{
return -1;
}
else
{
return curId;
}
}
} // loop over maximum possible candidates
// Nothing found
return -1;
}
/**
* Return the ith edge in the edge array. Either obtain a non-negative
* value i from IsInsertedEdge(); or use 0<=i<NumberOfEdges().
*/
const EdgeTupleType& GetEdge(IDType i) const { return (*this->EdgeArray)[i]; }
protected:
vtkIdType NumEdges;
// Support BuildLocator usage pattern
vtkIdType NumEdgesPerBin;
EdgeTupleType* EdgeArray;
IDType* EdgeOffsets;
IDType MinV0;
IDType MaxV0;
IDType V0Range;
int NDivs;
IDType HashBin(IDType v) const { return ((v - this->MinV0) / this->NumEdgesPerBin); }
IDType GetNumberOfEdgesInBin(IDType bin) const
{
return (this->EdgeOffsets[bin + 1] - this->EdgeOffsets[bin]);
}
// Support MergeEdges usage pattern
MergeTupleType* MergeArray;
std::vector<IDType> MergeOffsets;
private:
vtkStaticEdgeLocatorTemplate(const vtkStaticEdgeLocatorTemplate&) = delete;
void operator=(const vtkStaticEdgeLocatorTemplate&) = delete;
};
#include "vtkStaticEdgeLocatorTemplate.txx"
#endif
// VTK-HeaderTest-Exclude: vtkStaticEdgeLocatorTemplate.h