BezierCurveT_impl.hh

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//=============================================================================
//
//  CLASS BezierCurve - IMPLEMENTATION
//
//=============================================================================

#define ACG_BEZIERCURVE_C

//== INCLUDES =================================================================


#include "BezierCurveT.hh"


//== IMPLEMENTATION ========================================================== 


namespace ACG {


//-----------------------------------------------------------------------------


template <class Point>
Point
BezierCurveT<Point>::
operator()(Scalar _t) const
{
  // copy controll points
  std::vector<Point> b(*this);

  unsigned int n = b.size()-1, k;
  Scalar t0(1.0-_t), t1(_t);


  // de Casteljau
  unsigned int i, j;
  for (i=0; i<n; ++i)
    for (j=0, k=n-i; j<k; ++j)
      b[j] = t0*b[j] + t1*b[j+1];


  return b[0];
}


//-----------------------------------------------------------------------------


template <class Point>
void
BezierCurveT<Point>::
subdivide(Scalar _t, Self& _curve0, Self& _curve1) const
{
  // copy controll points
  std::vector<Point> b(*this);

  int n = degree();
  Scalar t0(1.0-_t), t1(_t);


  _curve0.clear();
  _curve0.reserve(n+1);
  _curve1.clear();
  _curve1.reserve(n+1);

  std::vector<Point>  tmp;
  tmp.reserve(n+1);


  // de Casteljau
  int i, j, k;
  for (i=0; i<n; ++i)
  {
    _curve0.push_back(b[0]);
    tmp.push_back(b[n-i]);

    for (j=0, k=n-i; j<k; ++j)
      b[j] = t0*b[j] + t1*b[j+1];
  }

  _curve0.push_back(b[0]);
  tmp.push_back(b[0]);


  for (i=n; i>=0; --i)
    _curve1.push_back(tmp[i]);


  assert(_curve0.degree() == n);
  assert(_curve1.degree() == n);
}


//=============================================================================
} // namespace ACG
//=============================================================================