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/**
* @class vtkIntersectionCounter
* @brief Fast simple class for dealing with ray intersections
*
* vtkIntersectionCounter is used to intersect data and merge coincident
* points along the intersect ray. It is light-weight and many of the member
* functions are in-lined so its very fast. It is not derived from vtkObject
* so it can be allocated on the stack.
*
* This class makes the finite ray intersection process more robust. It
* merges intersections that are very close to one another (within a
* tolerance). Such situations are common when intersection rays pass through
* the edge or vertex of a mesh.
*
* @sa
* vtkBoundingBox
*/
#ifndef vtkIntersectionCounter_h
#define vtkIntersectionCounter_h
#include "vtkCommonDataModelModule.h" // For export macro
#include "vtkSystemIncludes.h"
#include <algorithm> // for sorting
#include <vector> // for implementation
// class VTKCOMMONDATAMODEL_EXPORT vtkIntersectionCounter
VTK_ABI_NAMESPACE_BEGIN
class vtkIntersectionCounter
{
public:
///@{
/**
* This tolerance must be converted to parametric space. Here tol is the
* tolerance in world coordinates; length is the ray length.
*/
vtkIntersectionCounter()
: Tolerance(0.0001)
{
}
vtkIntersectionCounter(double tol, double length)
{
this->Tolerance = (length > 0.0 ? (tol / length) : 0.0);
}
///@}
/**
* Set/Get the intersection tolerance.
*/
void SetTolerance(double tol) { this->Tolerance = (tol < 0.0 ? 0.0001 : tol); }
double GetTolerance() { return this->Tolerance; }
/**
* Add an intersection given by parametric coordinate t.
*/
void AddIntersection(double t) { IntsArray.push_back(t); }
/**
* Reset the intersection process.
*/
void Reset() { IntsArray.clear(); }
/**
* Returns number of intersections (even number of intersections, outside
* or odd number of intersections, inside). This is done by considering
* close intersections (within Tolerance) as being the same point.
*/
int CountIntersections()
{
int size = static_cast<int>(IntsArray.size());
// Fast check for trivial cases
if (size <= 1)
{
return size; // 0 or 1
}
// Need to work harder: sort and then count the intersections
std::sort(IntsArray.begin(), IntsArray.end());
// If here, there is at least one intersection, and two inserted
// intersection points
int numInts = 1;
std::vector<double>::iterator i0 = IntsArray.begin();
std::vector<double>::iterator i1 = i0 + 1;
// Now march through sorted array counting "separated" intersections
while (i1 != IntsArray.end())
{
if ((*i1 - *i0) > this->Tolerance)
{
numInts++;
i0 = i1;
}
i1++;
}
return numInts;
}
protected:
double Tolerance;
std::vector<double> IntsArray;
}; // vtkIntersectionCounter
VTK_ABI_NAMESPACE_END
#endif
// VTK-HeaderTest-Exclude: vtkIntersectionCounter.h
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