LinearPWI.h

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/*
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   Copyright (c) 2009 Scientific Computing and Imaging Institute,
   University of Utah.

   
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///
///@class LinearPWI
///@brief Linear piecewise interpolation templates
///
///@author
///       Alexei Samsonov
///       Department of Computer Science
///       University of Utah
///
///@date  July 2000
///


#ifndef SCI_LINEARPWI_H__
#define SCI_LINEARPWI_H__

#include <Core/Math/PiecewiseInterp.h>

#include <Core/Containers/Array1.h>
#include <Core/GeometryPrimitives/Point.h>

namespace SCIRun {


typedef struct Pair{
  double a;
  double b; 
} PAIR;


class LinearPWI: public PiecewiseInterp<double> {
public:
    LinearPWI();
    LinearPWI(const Array1<double>&, const Array1<double>&);

    bool set_data(const Array1<double>&, const Array1<double>&);
    inline bool get_value(double, double&);

private:
    Array1<PAIR> p;
};

inline bool LinearPWI::get_value(double w, double& res){
  int interv;
  if (data_valid && (interv=get_interval(w))>=0){
    res=p[interv].a+p[interv].b*w;
    return true;
  }
  else
    return false;
}

template <class T> class Linear3DPWI: public PiecewiseInterp<T> {
public:
  Linear3DPWI() {}
  Linear3DPWI(const Array1<double>&, const Array1<T>&);
  
  bool set_data(const Array1<double>&, const Array1<T>&);
  inline bool get_value(double, T&);
  
private:
  Array1<PAIR> X;
  Array1<PAIR> Y;
  Array1<PAIR> Z;
};


template <class T> Linear3DPWI<T>::Linear3DPWI(const Array1<double>& pts, const Array1<T>& vals)
{
  set_data(pts, vals);  
}

template <class T> inline bool Linear3DPWI<T>::get_value(double w, T& res)
{
  int i = 0;
  if (this->data_valid && (i = this->get_interval(w)) >= 0) {
    res = T(X[i].a + X[i].b * w, Y[i].a+Y[i].b * w, Z[i].a + Z[i].b * w);
    return true;
  }  
  else
    return false;
}
    
// takes sorted array of points
template <class T> bool Linear3DPWI<T>::set_data(const Array1<double>& pts, const Array1<T>& vals)
{
  int sz = 0;
  this->reset();
  if (this->fill_data(pts) && (sz = this->points.size()) > 1) {
    X.resize(sz);
    Y.resize(sz);
    Z.resize(sz);
    
    double lb, rb, delta;

    for (int i=0; i<this->points.size()-1; i++){
      lb = this->points[i];
      rb = this->points[i+1];
      delta = rb - lb;
      X[i].a = (vals[i].x() * rb-vals[i+1].x() * lb) / delta;
      X[i].b = (vals[i+1].x() - vals[i].x()) / delta;
      Y[i].a = (vals[i].y() * rb-vals[i+1].y() * lb) / delta;
      Y[i].b = (vals[i+1].y() - vals[i].y()) / delta;
      Z[i].a = (vals[i].z() * rb-vals[i+1].z() * lb) / delta;
      Z[i].b = (vals[i+1].z() - vals[i].z()) / delta;
    }
    return this->data_valid = true;
  }
  else{
    this->reset();
    return this->data_valid = false;
  }
}

} // End namespace SCIRun

#endif //SCI_LINEARPWI_H__