// @(#)root/physics:$Name$:$Id$
// Author: Peter Malzacher   19/06/99

/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
#ifndef ROOT_TRotation
#define ROOT_TRotation

#ifndef ROOT_TVector3
#include "TVector3.h"
#endif

class TRotation : public TObject {


public:

  class TRotationRow {
  public:
    inline TRotationRow(const TRotation &, int);
    inline Double_t operator [] (int) const;
  private:
    const TRotation * rr;
    //    const TRotation & rr;
    int ii;
  };
  // Helper class for implemention of C-style subscripting r[i][j]

  TRotation();
  // Default constructor. Gives a unit matrix.

  TRotation(const TRotation &);
  // Copy constructor.

  inline Double_t XX() const;
  inline Double_t XY() const;
  inline Double_t XZ() const;
  inline Double_t YX() const;
  inline Double_t YY() const;
  inline Double_t YZ() const;
  inline Double_t ZX() const;
  inline Double_t ZY() const;
  inline Double_t ZZ() const;
  // Elements of the rotation matrix (Geant4).

  inline TRotationRow operator [] (int) const;
  // Returns object of the helper class for C-style subscripting r[i][j]

  Double_t operator () (int, int) const;
  // Fortran-style subscripting: returns (i,j) element of the rotation matrix.

  inline TRotation & operator = (const TRotation &);
  // Assignment.

  inline Bool_t operator == (const TRotation &) const;
  inline Bool_t operator != (const TRotation &) const;
  // Comparisons (Geant4).

  inline Bool_t IsIdentity() const;
  // Returns true if the identity matrix (Geant4).

  inline TVector3 operator * (const TVector3 &) const;
  // Multiplication with a Hep3Vector.

  TRotation operator * (const TRotation &) const;
  inline TRotation & operator *= (const TRotation &);
  inline TRotation & Transform(const TRotation &);
  // Matrix multiplication.
  // Note a *= b; <=> a = a * b; while a.transform(b); <=> a = b * a;

  inline TRotation Inverse() const;
  // Returns the inverse.

  inline TRotation & Invert();
  // Inverts the Rotation matrix.

  TRotation & RotateX(Double_t);
  // Rotation around the x-axis.

  TRotation & RotateY(Double_t);
  // Rotation around the y-axis.

  TRotation & RotateZ(Double_t);
  // Rotation around the z-axis.

  TRotation & Rotate(Double_t, const TVector3 &);
  inline TRotation & Rotate(Double_t, const TVector3 *);
  // Rotation around a specified vector.

  TRotation & RotateAxes(const TVector3 & newX,
                           const TVector3 & newY,
                           const TVector3 & newZ);
  // Rotation of local axes (Geant4).

  Double_t PhiX() const;
  Double_t PhiY() const;
  Double_t PhiZ() const;
  Double_t ThetaX() const;
  Double_t ThetaY() const;
  Double_t ThetaZ() const;
  // Return angles (RADS) made by rotated axes against original axes (Geant4).

  void AngleAxis(Double_t &, TVector3 &) const;
  // Returns the rotation angle and rotation axis (Geant4).

protected:

  TRotation(Double_t, Double_t, Double_t, Double_t, Double_t,
                     Double_t, Double_t, Double_t, Double_t);
  // Protected constructor.

  Double_t fxx, fxy, fxz, fyx, fyy, fyz, fzx, fzy, fzz;
  // The matrix elements.

  ClassDef(TRotation,1) // Rotations of TVector3 objects

};



inline Double_t TRotation::XX() const { return fxx; }
inline Double_t TRotation::XY() const { return fxy; }
inline Double_t TRotation::XZ() const { return fxz; }
inline Double_t TRotation::YX() const { return fyx; }
inline Double_t TRotation::YY() const { return fyy; }
inline Double_t TRotation::YZ() const { return fyz; }
inline Double_t TRotation::ZX() const { return fzx; }
inline Double_t TRotation::ZY() const { return fzy; }
inline Double_t TRotation::ZZ() const { return fzz; }

inline TRotation::TRotationRow::TRotationRow
(const TRotation & r, int i) : rr(&r), ii(i) {}

inline Double_t TRotation::TRotationRow::operator [] (int jj) const {
  return rr->operator()(ii,jj);
}

inline
TRotation::TRotationRow TRotation::operator [] (int i) const {
  return TRotationRow(*this, i);
}

inline TRotation & TRotation::operator = (const TRotation & m) {
  fxx = m.fxx;
  fxy = m.fxy;
  fxz = m.fxz;
  fyx = m.fyx;
  fyy = m.fyy;
  fyz = m.fyz;
  fzx = m.fzx;
  fzy = m.fzy;
  fzz = m.fzz;
  return *this;
}

inline Bool_t TRotation::operator == (const TRotation& m) const {
  return (fxx == m.fxx && fxy == m.fxy && fxz == m.fxz &&
          fyx == m.fyx && fyy == m.fyy && fyz == m.fyz &&
          fzx == m.fzx && fzy == m.fzy && fzz == m.fzz) ? kTRUE : kFALSE;
}

inline Bool_t TRotation::operator != (const TRotation &m) const {
  return (fxx != m.fxx || fxy != m.fxy || fxz != m.fxz ||
          fyx != m.fyx || fyy != m.fyy || fyz != m.fyz ||
          fzx != m.fzx || fzy != m.fzy || fzz != m.fzz) ? kTRUE : kFALSE;
}

inline Bool_t TRotation::IsIdentity() const {
  return  (fxx == 1.0 && fxy == 0.0 && fxz == 0.0 &&
           fyx == 0.0 && fyy == 1.0 && fyz == 0.0 &&
           fzx == 0.0 && fzy == 0.0 && fzz == 1.0) ? kTRUE : kFALSE;
}

inline TVector3 TRotation::operator * (const TVector3 & p) const {
  return TVector3(fxx*p.X() + fxy*p.Y() + fxz*p.Z(),
                    fyx*p.X() + fyy*p.Y() + fyz*p.Z(),
                    fzx*p.X() + fzy*p.Y() + fzz*p.Z());
}

inline TRotation & TRotation::operator *= (const TRotation & m) {
  return *this = operator * (m);
}

inline TRotation & TRotation::Transform(const TRotation & m) {
  return *this = m.operator * (*this);
}

inline TRotation TRotation::Inverse() const {
  return TRotation(fxx, fyx, fzx, fxy, fyy, fzy, fxz, fyz, fzz);
}

inline TRotation & TRotation::Invert() {
  return *this=Inverse();
}

inline TRotation & TRotation::Rotate(Double_t psi, const TVector3 * p) {
  return Rotate(psi, *p);
}



#endif