G4TwistTrapAlphaSide.hh

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// $Id: G4TwistTrapAlphaSide.hh 67011 2013-01-29 16:17:41Z gcosmo $
// 
// --------------------------------------------------------------------
// GEANT 4 class header file
//
//
// G4TwistTrapAlphaSide
//
// Class description:
//
//  Class describing a twisted boundary surface for a trapezoid.

// Author:
//
//   27-Oct-2004 - O.Link (Oliver.Link@cern.ch)
//
// --------------------------------------------------------------------
#ifndef __G4TWISTTRAPALPHASIDE__
#define __G4TWISTTRAPALPHASIDE__

#include "G4VTwistSurface.hh"

#include <vector>

class G4TwistTrapAlphaSide : public G4VTwistSurface
{
  public:  // with description
   
    G4TwistTrapAlphaSide(const G4String &name,
                               G4double  PhiTwist, // twist angle
                               G4double  pDz,      // half z lenght
                               G4double  pTheta, // direction between end planes
                               G4double  pPhi,   // by polar and azimutal angles
                               G4double  pDy1,     // half y length at -pDz
                               G4double  pDx1,     // half x length at -pDz,-pDy
                               G4double  pDx2,     // half x length at -pDz,+pDy
                               G4double  pDy2,     // half y length at +pDz
                               G4double  pDx3,     // half x length at +pDz,-pDy
                               G4double  pDx4,     // half x length at +pDz,+pDy
                               G4double  pAlph,    // tilt angle at +pDz
                               G4double  AngleSide // parity
                         );
  
    virtual ~G4TwistTrapAlphaSide();
   
    virtual G4ThreeVector  GetNormal(const G4ThreeVector &xx,
                                           G4bool isGlobal = false) ;   
   
    virtual G4int DistanceToSurface(const G4ThreeVector &gp,
                                    const G4ThreeVector &gv,
                                          G4ThreeVector  gxx[],
                                          G4double  distance[],
                                          G4int     areacode[],
                                          G4bool    isvalid[],
                                    EValidate validate = kValidateWithTol);
                                                  
    virtual G4int DistanceToSurface(const G4ThreeVector &gp,
                                          G4ThreeVector  gxx[],
                                          G4double       distance[],
                                          G4int          areacode[]);


  public:  // without description

    G4TwistTrapAlphaSide(__void__&);
      // Fake default constructor for usage restricted to direct object
      // persistency for clients requiring preallocation of memory for
      // persistifiable objects.

  private:

    virtual G4int GetAreaCode(const G4ThreeVector &xx, 
                                    G4bool         withTol = true);
    virtual void SetCorners();
    virtual void SetBoundaries();

    void GetPhiUAtX(G4ThreeVector p, G4double &phi, G4double &u);
    G4ThreeVector ProjectPoint(const G4ThreeVector &p,
                                     G4bool isglobal = false);

    virtual G4ThreeVector SurfacePoint(G4double phi, G4double u,
                                       G4bool isGlobal = false );
    virtual G4double GetBoundaryMin(G4double phi);
    virtual G4double GetBoundaryMax(G4double phi);
    virtual G4double GetSurfaceArea();
    virtual void GetFacets( G4int m, G4int n, G4double xyz[][3],
                            G4int faces[][4], G4int iside );

    inline G4ThreeVector NormAng(G4double phi, G4double u);
    inline G4double GetValueA(G4double phi);
    inline G4double GetValueB(G4double phi);
    inline G4double GetValueD(G4double phi);
    inline G4double Xcoef(G4double u,G4double phi);
      // To calculate the w(u) function

  private:

    G4double fTheta;   
    G4double fPhi ;

    G4double fDy1;   
    G4double fDx1;     
    G4double fDx2;     

    G4double fDy2;   
    G4double fDx3;     
    G4double fDx4;     

    G4double fDz;         // Half-length along the z axis

    G4double fAlph;
    G4double fTAlph;      // std::tan(fAlph)
    
    G4double fPhiTwist;   // twist angle (dphi in surface equation)

    G4double fAngleSide;

    G4double fDx4plus2;  // fDx4 + fDx2  == a2/2 + a1/2
    G4double fDx4minus2; // fDx4 - fDx2          -
    G4double fDx3plus1;  // fDx3 + fDx1  == d2/2 + d1/2
    G4double fDx3minus1; // fDx3 - fDx1          -
    G4double fDy2plus1;  // fDy2 + fDy1  == b2/2 + b1/2
    G4double fDy2minus1; // fDy2 - fDy1          -
    G4double fa1md1;     // 2 fDx2 - 2 fDx1  == a1 - d1
    G4double fa2md2;     // 2 fDx4 - 2 fDx3 

    G4double fdeltaX;
    G4double fdeltaY;
};   

//========================================================
// inline functions
//========================================================

inline
G4double G4TwistTrapAlphaSide::GetValueA(G4double phi)
{
  return ( fDx4plus2 + fDx4minus2 * ( 2 * phi ) / fPhiTwist  ) ;
}

inline
G4double G4TwistTrapAlphaSide::GetValueD(G4double phi) 
{
  return ( fDx3plus1 + fDx3minus1 * ( 2 * phi) / fPhiTwist  ) ;
} 

inline 
G4double G4TwistTrapAlphaSide::GetValueB(G4double phi) 
{
  return ( fDy2plus1 + fDy2minus1 * ( 2 * phi ) / fPhiTwist ) ;
}


inline
G4double G4TwistTrapAlphaSide::Xcoef(G4double u, G4double phi)
{
  
  return GetValueA(phi)/2. + (GetValueD(phi)-GetValueA(phi))/4. 
    - u*( ( GetValueD(phi)-GetValueA(phi) )/( 2 * GetValueB(phi) ) - fTAlph );

}

inline G4ThreeVector
G4TwistTrapAlphaSide::SurfacePoint(G4double phi, G4double u , G4bool isGlobal)
{
  // function to calculate a point on the surface, given by parameters phi,u

  G4ThreeVector SurfPoint ( Xcoef(u,phi) * std::cos(phi)
                          - u * std::sin(phi) + fdeltaX*phi/fPhiTwist,
                            Xcoef(u,phi) * std::sin(phi)
                          + u * std::cos(phi) + fdeltaY*phi/fPhiTwist,
                            2*fDz*phi/fPhiTwist  );
  if (isGlobal) { return (fRot * SurfPoint + fTrans); }
  return SurfPoint;
}

inline
G4double G4TwistTrapAlphaSide::GetBoundaryMin(G4double phi)
{
  return -0.5*GetValueB(phi) ;
}

inline
G4double G4TwistTrapAlphaSide::GetBoundaryMax(G4double phi)
{
  return 0.5*GetValueB(phi) ;
}

inline
G4double G4TwistTrapAlphaSide::GetSurfaceArea()
{
  return (fDz*(std::sqrt(16*fDy1*fDy1
             + (fa1md1 + 4*fDy1*fTAlph)*(fa1md1 + 4*fDy1*fTAlph))
             + std::sqrt(16*fDy2*fDy2 + (fa2md2 + 4*fDy2*fTAlph)
                                      * (fa2md2 + 4*fDy2*fTAlph))))/2. ;
}

inline
G4ThreeVector G4TwistTrapAlphaSide::NormAng( G4double phi, G4double u ) 
{
  // function to calculate the norm at a given point on the surface
  // replace a1-d1

  G4ThreeVector nvec ( fDy1* fDz*(4*fDy1*std::cos(phi)
                     + (fa1md1 + 4*fDy1*fTAlph)*std::sin(phi)),
                       -(fDy1* fDz*((fa1md1 + 4*fDy1*fTAlph)*std::cos(phi)
                     - 4*fDy1*std::sin(phi))),
                       (fDy1*(-8*(fDx3minus1 + fDx4minus2)*fDy1
                                + fa1md1*(fDx2 + fDx3plus1 + fDx4)*fPhiTwist
                                + 4*(fDx2 + fDx3plus1 + fDx4)*fDy1*fPhiTwist
                                *fTAlph + 2*(fDx3minus1 + fDx4minus2)
                                *(fa1md1 + 4*fDy1*fTAlph)*phi)
                                + fPhiTwist*(16*fDy1*fDy1
                                + (fa1md1 + 4*fDy1*fTAlph)
                                *(fa1md1 + 4*fDy1*fTAlph))*u
                                + 4*fDy1*(fa1md1*fdeltaY - 4*fdeltaX*fDy1
                                + 4*fdeltaY*fDy1*fTAlph)* std::cos(phi)
                                - 4*fDy1*(fa1md1*fdeltaX + 4*fDy1*(fdeltaY
                                + fdeltaX*fTAlph))*std::sin(phi))/ 8. ) ;
    return nvec.unit();
}

#endif

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