Area2D.cc

//-----------------------------------------------------------------------------
// $Id$
//-----------------------------------------------------------------------------
// Filename : TRGArea2D.h
// Section  : TRG
// Owner    : Yoshihito Iwasaki
// Email    : yoshihito.iwasaki@kek.jp
//-----------------------------------------------------------------------------
// Description : A class to represent a 2D area.
//-----------------------------------------------------------------------------
// $Log$
//-----------------------------------------------------------------------------
 
#include "trg/trg/Area2D.h"
 
namespace Belle2 {
  TRGArea2D::TRGArea2D(const TRGPoint2D& leftBottom,
                       const TRGPoint2D& rightUpper)
  {
    _c[0] = leftBottom;
    _c[1] = rightUpper;
  }
 
  TRGArea2D::~TRGArea2D()
  {
  }
 
  void
  TRGArea2D::cross(const TRGPoint2D& x0,
                   const TRGPoint2D& x1,
                   unsigned& nFound,
                   TRGPoint2D crossPoint[2]) const
  {
 
    //...Parameters...
    const float xDiff = x1.x() - x0.x();
    const float yDiff = x1.y() - x0.y();
    const float a = yDiff / xDiff;
    const float b = x0.x() - a * x0.x();
 
    //...Find cross-points...
    nFound = 0;
    for (unsigned i = 0; i < 2; i++) {
 
      TRGPoint2D p(_c[i].x(), a * _c[i].x() + b);
      if (inArea(p))
        crossPoint[nFound++] = p;
      if (nFound == 2) return;
 
      TRGPoint2D q((_c[i].y() - b) / a, _c[i].y());
      if (inArea(q))
        crossPoint[nFound++] = q;
      if (nFound == 2) return;
    }
  }
 
} // namespace Belle2