FairGeoTransform.cxx

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//*-- AUTHOR : Ilse Koenig
//*-- Modified : 16/06/1999
//*-- Modified : 21/06/2005 D.Bertini

//
// FairGeoTransform
//
// Class to hold the orientation (rotation matrix) and the position
// (translation vector) of a coordinate system (system 2) relative to a
// reference coordinate system (system 1)
// It provides member functions to transform a vector or a point and an other
// coordinate system from its own coordinate system into the reference
// coordinate system and vice versa.
// Instances of this class can e.g. hold the lab or detector transformation of
// a geometry volume (see class FairGeoVolume)
//
// Inline functions:
//
// FairGeoTransform()
//    The default constructor creates an identity transformation
// FairGeoTransform(FairGeoTransform& t)
//    copy constructor
// void setTransform(const FairGeoTransform& t)
//    copies the given transformation
// void setRotMatrix(const FairGeoRotation& r)
//    copies the given rotation matrix
// void setRotMatrix(const Double_t* a)
//    creates a rotation matrix taking an Double_t array with 9 components
// void setTransVector(const FairGeoVector& t)
//    copies the given translation vector
// void setTransVector(const Double_t* a)
//    creates a translation vector taking an Double_t array with 6 components
// const FairGeoRotation& getRotMatrix() const
//    returns the rotation matrix
// const FairGeoVector& getTransVector() const
//    returns the  translation vector
//

#include "FairGeoTransform.h"

//#include <iostream>
//#include <iomanip>
//#include "math.h"

ClassImp(FairGeoTransform)
FairGeoTransform::FairGeoTransform()
  : TObject(),
    rot(FairGeoRotation(0,0,0)),
    trans(FairGeoVector(0,0,0)),
    trans_cm(FairGeoVector(0,0,0))
{

}
FairGeoTransform& FairGeoTransform::operator=(const FairGeoTransform& t)
{
  rot=t.getRotMatrix();
  trans=t.getTransVector();

  return *this;
}


FairGeoVector FairGeoTransform::transFrom(const FairGeoVector& p) const
{
  // Transforms a vector (point) given in its own coordinate
  // system (2) into the reference coordinate system (1)
  // e.g. v2 is a vector (point) in the detector coordinate system;
  // it can be transformed to a vector v2 the lab system with
  //    FairGeoVector v2=mo.transFrom(v1)
  // where mo is the coordinate system of the mother
  return rot*p+trans;
}

FairGeoVector FairGeoTransform::transTo(const FairGeoVector& p) const
{
  // Transforms a vector (point) given in the reference system (1)
  // into the local coordinate system (2)
  // e.g. v1 is a vector (point) in the lab system; it can be transformed to
  // a vector v2 the detector coordinate system with
  //    FairGeoVector v2=mo.transTo(v1)
  // where mo is the coordinate system of the mother
  return rot.inverse()*(p-trans);
}

void FairGeoTransform::transTo(const FairGeoTransform& s)
{
  // Transforms the coordinate system into the coordinate system
  // described by s. Both transformations must have the same reference
  // system e.g. the lab system
  // This function is e.g. used to transform a daughter coordinate system
  // with a transformation relative to the lab into the detector coordinate
  // system.
  const FairGeoRotation& rm=s.getRotMatrix();
  FairGeoRotation rt(rm.inverse());
  if (rm.diff2(rot)<0.000001) { rot.setUnitMatrix(); }
  else { rot.transform(rt); }
  trans-=s.getTransVector();
  trans=rt*trans;
  //  trans.round(3); // rounds to 3 digits (precision 1 micrometer)
}

void FairGeoTransform::transFrom(const FairGeoTransform& s)
{
  // Transforms the coordinate system described by s into the local
  // coordinate system
  // This function is e.g. used to transform a daughter coordinate system
  // with a transformation relative to its mother into the lab system.
  // e.g. daughterDetTransform.transFrom(motherLabTransform)
  const FairGeoRotation& r=s.getRotMatrix();
  rot.transform(r);
  trans=r*trans;
  trans+=s.getTransVector();
}

void FairGeoTransform::clear()
{
  trans.clear();
  rot.setUnitMatrix();
}

void FairGeoTransform::print()
{
  rot.print();
  trans.print();
}

void FairGeoTransform::invert(void)
{
  rot.invert();
  trans = rot*trans;
  trans *= -1.;
}