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