G4TwistedTubs.cc

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// $Id: G4TwistedTubs.cc 83572 2014-09-01 15:23:27Z gcosmo $
//
// 
// --------------------------------------------------------------------
// GEANT 4 class source file
//
//
// G4TwistTubsSide.cc
//
// Author: 
//   01-Aug-2002 - Kotoyo Hoshina (hoshina@hepburn.s.chiba-u.ac.jp)
//
// History:
//   13-Nov-2003 - O.Link (Oliver.Link@cern.ch), Integration in Geant4
//                 from original version in Jupiter-2.5.02 application.
// --------------------------------------------------------------------

#include "G4TwistedTubs.hh"

#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4GeometryTolerance.hh"
#include "G4VoxelLimits.hh"
#include "G4AffineTransform.hh"
#include "G4SolidExtentList.hh"
#include "G4ClippablePolygon.hh"
#include "G4VPVParameterisation.hh"
#include "meshdefs.hh"

#include "G4VGraphicsScene.hh"
#include "G4Polyhedron.hh"
#include "G4VisExtent.hh"

#include "Randomize.hh"

#include "G4AutoLock.hh"

namespace
{
  G4Mutex polyhedronMutex = G4MUTEX_INITIALIZER;
}

//=====================================================================
//* constructors ------------------------------------------------------

G4TwistedTubs::G4TwistedTubs(const G4String &pname,
                                   G4double  twistedangle,
                                   G4double  endinnerrad,
                                   G4double  endouterrad,
                                   G4double  halfzlen,
                                   G4double  dphi)
   : G4VSolid(pname), fDPhi(dphi), 
     fLowerEndcap(0), fUpperEndcap(0), fLatterTwisted(0),
     fFormerTwisted(0), fInnerHype(0), fOuterHype(0),
     fCubicVolume(0.), fSurfaceArea(0.),
     fRebuildPolyhedron(false), fpPolyhedron(0)
{
   if (endinnerrad < DBL_MIN)
   {
      G4Exception("G4TwistedTubs::G4TwistedTubs()", "GeomSolids0002",
                  FatalErrorInArgument, "Invalid end-inner-radius!");
   }
            
   G4double sinhalftwist = std::sin(0.5 * twistedangle);

   G4double endinnerradX = endinnerrad * sinhalftwist;
   G4double innerrad     = std::sqrt( endinnerrad * endinnerrad
                                 - endinnerradX * endinnerradX );

   G4double endouterradX = endouterrad * sinhalftwist;
   G4double outerrad     = std::sqrt( endouterrad * endouterrad
                                 - endouterradX * endouterradX );
   
   // temporary treatment!!
   SetFields(twistedangle, innerrad, outerrad, -halfzlen, halfzlen);
   CreateSurfaces();
}

G4TwistedTubs::G4TwistedTubs(const G4String &pname,     
                                   G4double  twistedangle,    
                                   G4double  endinnerrad,  
                                   G4double  endouterrad,  
                                   G4double  halfzlen,
                                   G4int     nseg,
                                   G4double  totphi)
   : G4VSolid(pname),
     fLowerEndcap(0), fUpperEndcap(0), fLatterTwisted(0),
     fFormerTwisted(0), fInnerHype(0), fOuterHype(0),
     fCubicVolume(0.), fSurfaceArea(0.),
     fRebuildPolyhedron(false), fpPolyhedron(0)
{

   if (!nseg)
   {
      std::ostringstream message;
      message << "Invalid number of segments." << G4endl
              << "        nseg = " << nseg;
      G4Exception("G4TwistedTubs::G4TwistedTubs()", "GeomSolids0002",
                  FatalErrorInArgument, message);
   }
   if (totphi == DBL_MIN || endinnerrad < DBL_MIN)
   {
      G4Exception("G4TwistedTubs::G4TwistedTubs()", "GeomSolids0002",
                FatalErrorInArgument, "Invalid total-phi or end-inner-radius!");
   }
         
   G4double sinhalftwist = std::sin(0.5 * twistedangle);

   G4double endinnerradX = endinnerrad * sinhalftwist;
   G4double innerrad     = std::sqrt( endinnerrad * endinnerrad
                                 - endinnerradX * endinnerradX );

   G4double endouterradX = endouterrad * sinhalftwist;
   G4double outerrad     = std::sqrt( endouterrad * endouterrad
                                 - endouterradX * endouterradX );
   
   // temporary treatment!!
   fDPhi = totphi / nseg;
   SetFields(twistedangle, innerrad, outerrad, -halfzlen, halfzlen);
   CreateSurfaces();
}

G4TwistedTubs::G4TwistedTubs(const G4String &pname,
                                   G4double  twistedangle,
                                   G4double  innerrad,
                                   G4double  outerrad,
                                   G4double  negativeEndz,
                                   G4double  positiveEndz,
                                   G4double  dphi)
   : G4VSolid(pname), fDPhi(dphi),
     fLowerEndcap(0), fUpperEndcap(0), fLatterTwisted(0),
     fFormerTwisted(0), fInnerHype(0), fOuterHype(0),
     fCubicVolume(0.), fSurfaceArea(0.),
     fRebuildPolyhedron(false), fpPolyhedron(0)
{
   if (innerrad < DBL_MIN)
   {
      G4Exception("G4TwistedTubs::G4TwistedTubs()", "GeomSolids0002",
                  FatalErrorInArgument, "Invalid end-inner-radius!");
   }
                 
   SetFields(twistedangle, innerrad, outerrad, negativeEndz, positiveEndz);
   CreateSurfaces();
}

G4TwistedTubs::G4TwistedTubs(const G4String &pname,     
                                   G4double  twistedangle,    
                                   G4double  innerrad,  
                                   G4double  outerrad,  
                                   G4double  negativeEndz,
                                   G4double  positiveEndz,
                                   G4int     nseg,
                                   G4double  totphi)
   : G4VSolid(pname),
     fLowerEndcap(0), fUpperEndcap(0), fLatterTwisted(0),
     fFormerTwisted(0), fInnerHype(0), fOuterHype(0),
     fCubicVolume(0.), fSurfaceArea(0.),
     fRebuildPolyhedron(false), fpPolyhedron(0)
{
   if (!nseg)
   {
      std::ostringstream message;
      message << "Invalid number of segments." << G4endl
              << "        nseg = " << nseg;
      G4Exception("G4TwistedTubs::G4TwistedTubs()", "GeomSolids0002",
                  FatalErrorInArgument, message);
   }
   if (totphi == DBL_MIN || innerrad < DBL_MIN)
   {
      G4Exception("G4TwistedTubs::G4TwistedTubs()", "GeomSolids0002",
                FatalErrorInArgument, "Invalid total-phi or end-inner-radius!");
   }
            
   fDPhi = totphi / nseg;
   SetFields(twistedangle, innerrad, outerrad, negativeEndz, positiveEndz);
   CreateSurfaces();
}

//=====================================================================
//* Fake default constructor ------------------------------------------

G4TwistedTubs::G4TwistedTubs( __void__& a )
  : G4VSolid(a), fPhiTwist(0.), fInnerRadius(0.), fOuterRadius(0.), fDPhi(0.),
    fZHalfLength(0.), fInnerStereo(0.), fOuterStereo(0.), fTanInnerStereo(0.),
    fTanOuterStereo(0.), fKappa(0.), fInnerRadius2(0.), fOuterRadius2(0.),
    fTanInnerStereo2(0.), fTanOuterStereo2(0.), fLowerEndcap(0), fUpperEndcap(0),
    fLatterTwisted(0), fFormerTwisted(0), fInnerHype(0), fOuterHype(0),
    fCubicVolume(0.), fSurfaceArea(0.),
    fRebuildPolyhedron(false), fpPolyhedron(0)
{
}

//=====================================================================
//* destructor --------------------------------------------------------

G4TwistedTubs::~G4TwistedTubs()
{
   if (fLowerEndcap)   { delete fLowerEndcap;   }
   if (fUpperEndcap)   { delete fUpperEndcap;   }
   if (fLatterTwisted) { delete fLatterTwisted; }
   if (fFormerTwisted) { delete fFormerTwisted; }
   if (fInnerHype)     { delete fInnerHype;     }
   if (fOuterHype)     { delete fOuterHype;     }
   if (fpPolyhedron)   { delete fpPolyhedron; fpPolyhedron = 0; }
}

//=====================================================================
//* Copy constructor --------------------------------------------------

G4TwistedTubs::G4TwistedTubs(const G4TwistedTubs& rhs)
  : G4VSolid(rhs), fPhiTwist(rhs.fPhiTwist),
    fInnerRadius(rhs.fInnerRadius), fOuterRadius(rhs.fOuterRadius),
    fDPhi(rhs.fDPhi), fZHalfLength(rhs.fZHalfLength),
    fInnerStereo(rhs.fInnerStereo), fOuterStereo(rhs.fOuterStereo),
    fTanInnerStereo(rhs.fTanInnerStereo), fTanOuterStereo(rhs.fTanOuterStereo),
    fKappa(rhs.fKappa), fInnerRadius2(rhs.fInnerRadius2), 
    fOuterRadius2(rhs.fOuterRadius2), fTanInnerStereo2(rhs.fTanInnerStereo2),
    fTanOuterStereo2(rhs.fTanOuterStereo2),
    fLowerEndcap(0), fUpperEndcap(0), fLatterTwisted(0), fFormerTwisted(0),
    fInnerHype(0), fOuterHype(0),
    fCubicVolume(rhs.fCubicVolume), fSurfaceArea(rhs.fSurfaceArea),
    fRebuildPolyhedron(false), fpPolyhedron(0),
    fLastInside(rhs.fLastInside), fLastNormal(rhs.fLastNormal),
    fLastDistanceToIn(rhs.fLastDistanceToIn),
    fLastDistanceToOut(rhs.fLastDistanceToOut),
    fLastDistanceToInWithV(rhs.fLastDistanceToInWithV),
    fLastDistanceToOutWithV(rhs.fLastDistanceToOutWithV)
{
  for (size_t i=0; i<2; ++i)
  {
    fEndZ[i] = rhs.fEndZ[i];
    fEndInnerRadius[i] = rhs.fEndInnerRadius[i];
    fEndOuterRadius[i] = rhs.fEndOuterRadius[i];
    fEndPhi[i] = rhs.fEndPhi[i];
    fEndZ2[i] = rhs.fEndZ2[i];
  }
  CreateSurfaces();
}


//=====================================================================
//* Assignment operator -----------------------------------------------

G4TwistedTubs& G4TwistedTubs::operator = (const G4TwistedTubs& rhs) 
{
   // Check assignment to self
   //
   if (this == &rhs)  { return *this; }

   // Copy base class data
   //
   G4VSolid::operator=(rhs);

   // Copy data
   //
   fPhiTwist= rhs.fPhiTwist;
   fInnerRadius= rhs.fInnerRadius; fOuterRadius= rhs.fOuterRadius;
   fDPhi= rhs.fDPhi; fZHalfLength= rhs.fZHalfLength;
   fInnerStereo= rhs.fInnerStereo; fOuterStereo= rhs.fOuterStereo;
   fTanInnerStereo= rhs.fTanInnerStereo; fTanOuterStereo= rhs.fTanOuterStereo;
   fKappa= rhs.fKappa; fInnerRadius2= rhs.fInnerRadius2; 
   fOuterRadius2= rhs.fOuterRadius2; fTanInnerStereo2= rhs.fTanInnerStereo2;
   fTanOuterStereo2= rhs.fTanOuterStereo2;
   fLowerEndcap= fUpperEndcap= fLatterTwisted= fFormerTwisted= 0;
   fInnerHype= fOuterHype= 0;
   fCubicVolume= rhs.fCubicVolume; fSurfaceArea= rhs.fSurfaceArea;
   fLastInside= rhs.fLastInside; fLastNormal= rhs.fLastNormal;
   fLastDistanceToIn= rhs.fLastDistanceToIn;
   fLastDistanceToOut= rhs.fLastDistanceToOut;
   fLastDistanceToInWithV= rhs.fLastDistanceToInWithV;
   fLastDistanceToOutWithV= rhs.fLastDistanceToOutWithV;
 
   for (size_t i=0; i<2; ++i)
   {
     fEndZ[i] = rhs.fEndZ[i];
     fEndInnerRadius[i] = rhs.fEndInnerRadius[i];
     fEndOuterRadius[i] = rhs.fEndOuterRadius[i];
     fEndPhi[i] = rhs.fEndPhi[i];
     fEndZ2[i] = rhs.fEndZ2[i];
   }
 
   CreateSurfaces();
   fRebuildPolyhedron = false;
   delete fpPolyhedron; fpPolyhedron = 0;

   return *this;
}

//=====================================================================
//* ComputeDimensions -------------------------------------------------

void G4TwistedTubs::ComputeDimensions(G4VPVParameterisation* /* p */ ,
                                      const G4int            /* n  */ ,
                                      const G4VPhysicalVolume* /* pRep */ )
{
  G4Exception("G4TwistedTubs::ComputeDimensions()",
              "GeomSolids0001", FatalException,
              "G4TwistedTubs does not support Parameterisation.");
}


//=====================================================================
//* CalculateExtent ---------------------------------------------------

G4bool G4TwistedTubs::CalculateExtent( const EAxis              axis,
                                       const G4VoxelLimits     &voxelLimit,
                                       const G4AffineTransform &transform,
                                             G4double          &min,
                                             G4double          &max ) const
{

  G4SolidExtentList  extentList( axis, voxelLimit );
  G4double maxEndOuterRad = (fEndOuterRadius[0] > fEndOuterRadius[1] ?
                             fEndOuterRadius[0] : fEndOuterRadius[1]);
  G4double maxEndInnerRad = (fEndInnerRadius[0] > fEndInnerRadius[1] ?
                             fEndInnerRadius[0] : fEndInnerRadius[1]);
  G4double maxphi         = (std::fabs(fEndPhi[0]) > std::fabs(fEndPhi[1]) ?
                             std::fabs(fEndPhi[0]) : std::fabs(fEndPhi[1]));
   
  //
  // Choose phi size of our segment(s) based on constants as
  // defined in meshdefs.hh
  //
  // G4int numPhi = kMaxMeshSections;
  G4double sigPhi = 2*maxphi + fDPhi;
  G4double rFudge = 1.0/std::cos(0.5*sigPhi);
  G4double fudgeEndOuterRad = rFudge * maxEndOuterRad;
  
  //
  // We work around in phi building polygons along the way.
  // As a reasonable compromise between accuracy and
  // complexity (=cpu time), the following facets are chosen:
  //
  //   1. If fOuterRadius/maxEndOuterRad > 0.95, approximate
  //      the outer surface as a cylinder, and use one
  //      rectangular polygon (0-1) to build its mesh.
  //
  //      Otherwise, use two trapazoidal polygons that 
  //      meet at z = 0 (0-4-1)
  //
  //   2. If there is no inner surface, then use one
  //      polygon for each entire endcap.  (0) and (1)
  //
  //      Otherwise, use a trapazoidal polygon for each
  //      phi segment of each endcap.    (0-2) and (1-3)
  //
  //   3. For the inner surface, if fInnerRadius/maxEndInnerRad > 0.95,
  //      approximate the inner surface as a cylinder of
  //      radius fInnerRadius and use one rectangular polygon
  //      to build each phi segment of its mesh.   (2-3)
  //
  //      Otherwise, use one rectangular polygon centered
  //      at z = 0 (5-6) and two connecting trapazoidal polygons
  //      for each phi segment (2-5) and (3-6).
  //

  G4bool splitOuter = (fOuterRadius/maxEndOuterRad < 0.95);
  G4bool splitInner = (fInnerRadius/maxEndInnerRad < 0.95);
  
  //
  // Vertex assignments (v and w arrays)
  // [0] and [1] are mandatory
  // the rest are optional
  //
  //     +                     -
  //      [0]------[4]------[1]      <--- outer radius
  //       |                 |       
  //       |                 |       
  //      [2]---[5]---[6]---[3]      <--- inner radius
  //

  G4ClippablePolygon endPoly1, endPoly2;
  
  G4double phimax   = maxphi + 0.5*fDPhi;
  if ( phimax > pi/2)  { phimax = pi-phimax; }
  G4double phimin   = - phimax;

  G4ThreeVector v0, v1, v2, v3, v4, v5, v6;   // -ve phi verticies for polygon
  G4ThreeVector w0, w1, w2, w3, w4, w5, w6;   // +ve phi verticies for polygon

  //
  // decide verticies of -ve phi boundary
  //
  
  G4double cosPhi = std::cos(phimin);
  G4double sinPhi = std::sin(phimin);
 
  // Outer hyperbolic surface  

  v0 = transform.TransformPoint( 
       G4ThreeVector(fudgeEndOuterRad*cosPhi, fudgeEndOuterRad*sinPhi, 
                     + fZHalfLength));
  v1 = transform.TransformPoint( 
       G4ThreeVector(fudgeEndOuterRad*cosPhi, fudgeEndOuterRad*sinPhi, 
                     - fZHalfLength));
  if (splitOuter)
  {
     v4 = transform.TransformPoint(
          G4ThreeVector(fudgeEndOuterRad*cosPhi, fudgeEndOuterRad*sinPhi, 0));
  }
  
  // Inner hyperbolic surface  

  G4double zInnerSplit = 0.;
  if (splitInner)
  {
     v2 = transform.TransformPoint( 
          G4ThreeVector(maxEndInnerRad*cosPhi, maxEndInnerRad*sinPhi, 
                        + fZHalfLength));
     v3 = transform.TransformPoint( 
          G4ThreeVector(maxEndInnerRad*cosPhi, maxEndInnerRad*sinPhi, 
                        - fZHalfLength));
      
     // Find intersection of tangential line of inner
     // surface at z = fZHalfLength and line r=fInnerRadius.
     G4double dr = fZHalfLength * fTanInnerStereo2;
     G4double dz = maxEndInnerRad;
     zInnerSplit = fZHalfLength + (fInnerRadius - maxEndInnerRad) * dz / dr;

     // Build associated vertices
     v5 = transform.TransformPoint( 
          G4ThreeVector(fInnerRadius*cosPhi, fInnerRadius*sinPhi, 
                        + zInnerSplit));
     v6 = transform.TransformPoint( 
          G4ThreeVector(fInnerRadius*cosPhi, fInnerRadius*sinPhi, 
                        - zInnerSplit));
  }
  else
  {
     v2 = transform.TransformPoint(
          G4ThreeVector(fInnerRadius*cosPhi, fInnerRadius*sinPhi, 
                        + fZHalfLength));
     v3 = transform.TransformPoint(
          G4ThreeVector(fInnerRadius*cosPhi, fInnerRadius*sinPhi, 
                        - fZHalfLength));
  }

  //
  // decide vertices of +ve phi boundary
  // 

  cosPhi = std::cos(phimax);
  sinPhi = std::sin(phimax);
   
  // Outer hyperbolic surface  
  
  w0 = transform.TransformPoint(
       G4ThreeVector(fudgeEndOuterRad*cosPhi, fudgeEndOuterRad*sinPhi,
                     + fZHalfLength));
  w1 = transform.TransformPoint(
       G4ThreeVector(fudgeEndOuterRad*cosPhi, fudgeEndOuterRad*sinPhi,
                     - fZHalfLength));
  if (splitOuter)
  {
     G4double r = rFudge*fOuterRadius;
     
     w4 = transform.TransformPoint(G4ThreeVector( r*cosPhi, r*sinPhi, 0 ));
      
     AddPolyToExtent( v0, v4, w4, w0, voxelLimit, axis, extentList );
     AddPolyToExtent( v4, v1, w1, w4, voxelLimit, axis, extentList );
  }
  else
  {
     AddPolyToExtent( v0, v1, w1, w0, voxelLimit, axis, extentList );
  }
  
  // Inner hyperbolic surface
  
  if (splitInner)
  {
     w2 = transform.TransformPoint(
          G4ThreeVector(maxEndInnerRad*cosPhi, maxEndInnerRad*sinPhi, 
                        + fZHalfLength));
     w3 = transform.TransformPoint(
          G4ThreeVector(maxEndInnerRad*cosPhi, maxEndInnerRad*sinPhi, 
                        - fZHalfLength));
          
     w5 = transform.TransformPoint(
          G4ThreeVector(fInnerRadius*cosPhi, fInnerRadius*sinPhi,
                        + zInnerSplit));
     w6 = transform.TransformPoint(
          G4ThreeVector(fInnerRadius*cosPhi, fInnerRadius*sinPhi,
                        - zInnerSplit));
                                   
     AddPolyToExtent( v3, v6, w6, w3, voxelLimit, axis, extentList );
     AddPolyToExtent( v6, v5, w5, w6, voxelLimit, axis, extentList );
     AddPolyToExtent( v5, v2, w2, w5, voxelLimit, axis, extentList );
     
  }
  else
  {
     w2 = transform.TransformPoint(
          G4ThreeVector(fInnerRadius*cosPhi, fInnerRadius*sinPhi,
                        + fZHalfLength));
     w3 = transform.TransformPoint(
          G4ThreeVector(fInnerRadius*cosPhi, fInnerRadius*sinPhi,
                        - fZHalfLength));

     AddPolyToExtent( v3, v2, w2, w3, voxelLimit, axis, extentList );
  }

  //
  // Endplate segments
  //
  AddPolyToExtent( v1, v3, w3, w1, voxelLimit, axis, extentList );
  AddPolyToExtent( v2, v0, w0, w2, voxelLimit, axis, extentList );
  
  //
  // Return min/max value
  //
  return extentList.GetExtent( min, max );
}


//=====================================================================
//* AddPolyToExtent ---------------------------------------------------

void G4TwistedTubs::AddPolyToExtent( const G4ThreeVector &v0,
                                     const G4ThreeVector &v1,
                                     const G4ThreeVector &w1,
                                     const G4ThreeVector &w0,
                                     const G4VoxelLimits &voxelLimit,
                                     const EAxis          axis,
                                     G4SolidExtentList   &extentList ) 
{
    // Utility function for CalculateExtent
    //
    G4ClippablePolygon phiPoly;

    phiPoly.AddVertexInOrder( v0 );
    phiPoly.AddVertexInOrder( v1 );
    phiPoly.AddVertexInOrder( w1 );
    phiPoly.AddVertexInOrder( w0 );

    if (phiPoly.PartialClip( voxelLimit, axis ))
    {
        phiPoly.SetNormal( (v1-v0).cross(w0-v0).unit() );
        extentList.AddSurface( phiPoly );
    }
}


//=====================================================================
//* Inside ------------------------------------------------------------

EInside G4TwistedTubs::Inside(const G4ThreeVector& p) const
{

   const G4double halftol
     = 0.5 * G4GeometryTolerance::GetInstance()->GetRadialTolerance();
   // static G4int timerid = -1;
   // G4Timer timer(timerid, "G4TwistedTubs", "Inside");
   // timer.Start();

   G4ThreeVector *tmpp;
   EInside       *tmpinside;
   if (fLastInside.p == p)
   {
     return fLastInside.inside;
   }
   else
   {
      tmpp      = const_cast<G4ThreeVector*>(&(fLastInside.p));
      tmpinside = const_cast<EInside*>(&(fLastInside.inside));
      tmpp->set(p.x(), p.y(), p.z());
   }
   
   EInside  outerhypearea = ((G4TwistTubsHypeSide *)fOuterHype)->Inside(p);
   G4double innerhyperho  = ((G4TwistTubsHypeSide *)fInnerHype)->GetRhoAtPZ(p);
   G4double distanceToOut = p.getRho() - innerhyperho; // +ve: inside

   if ((outerhypearea == kOutside) || (distanceToOut < -halftol))
   {
      *tmpinside = kOutside;
   }
   else if (outerhypearea == kSurface)
   {
      *tmpinside = kSurface;
   }
   else
   {
      if (distanceToOut <= halftol)
      {
         *tmpinside = kSurface;
      }
      else
      {
         *tmpinside = kInside;
      }
   }

   return fLastInside.inside;
}

//=====================================================================
//* SurfaceNormal -----------------------------------------------------

G4ThreeVector G4TwistedTubs::SurfaceNormal(const G4ThreeVector& p) const
{
   //
   // return the normal unit vector to the Hyperbolical Surface at a point 
   // p on (or nearly on) the surface
   //
   // Which of the three or four surfaces are we closest to?
   //

   if (fLastNormal.p == p)
   {
      return fLastNormal.vec;
   }    
   G4ThreeVector *tmpp          =
     const_cast<G4ThreeVector*>(&(fLastNormal.p));
   G4ThreeVector *tmpnormal     =
     const_cast<G4ThreeVector*>(&(fLastNormal.vec));
   G4VTwistSurface **tmpsurface =
     const_cast<G4VTwistSurface**>(fLastNormal.surface);
   tmpp->set(p.x(), p.y(), p.z());

   G4double      distance = kInfinity;

   G4VTwistSurface *surfaces[6];
   surfaces[0] = fLatterTwisted;
   surfaces[1] = fFormerTwisted;
   surfaces[2] = fInnerHype;
   surfaces[3] = fOuterHype;
   surfaces[4] = fLowerEndcap;
   surfaces[5] = fUpperEndcap;

   G4ThreeVector xx;
   G4ThreeVector bestxx;
   G4int i;
   G4int besti = -1;
   for (i=0; i< 6; i++)
   {
      G4double tmpdistance = surfaces[i]->DistanceTo(p, xx);
      if (tmpdistance < distance)
      {
         distance = tmpdistance;
         bestxx = xx;
         besti = i; 
      }
   }

   tmpsurface[0] = surfaces[besti];
   *tmpnormal = tmpsurface[0]->GetNormal(bestxx, true);
   
   return fLastNormal.vec;
}

//=====================================================================
//* DistanceToIn (p, v) -----------------------------------------------

G4double G4TwistedTubs::DistanceToIn (const G4ThreeVector& p,
                                      const G4ThreeVector& v ) const
{

   // DistanceToIn (p, v):
   // Calculate distance to surface of shape from `outside' 
   // along with the v, allowing for tolerance.
   // The function returns kInfinity if no intersection or
   // just grazing within tolerance.

   //
   // checking last value
   //
   
   G4ThreeVector *tmpp;
   G4ThreeVector *tmpv;
   G4double      *tmpdist;
   if ((fLastDistanceToInWithV.p == p) && (fLastDistanceToInWithV.vec == v))
   {
     return fLastDistanceToIn.value;
   }
   else
   {
      tmpp    = const_cast<G4ThreeVector*>(&(fLastDistanceToInWithV.p));
      tmpv    = const_cast<G4ThreeVector*>(&(fLastDistanceToInWithV.vec));
      tmpdist = const_cast<G4double*>(&(fLastDistanceToInWithV.value));
      tmpp->set(p.x(), p.y(), p.z());
      tmpv->set(v.x(), v.y(), v.z());
   }

   //
   // Calculate DistanceToIn(p,v)
   //
   
   EInside currentside = Inside(p);

   if (currentside == kInside)
   {
   }
   else
   {
     if (currentside == kSurface)
     {
       // particle is just on a boundary.
       // If the particle is entering to the volume, return 0.
       //
       G4ThreeVector normal = SurfaceNormal(p);
       if (normal*v < 0)
       {
         *tmpdist = 0;
         return fLastDistanceToInWithV.value;
       } 
     }
   }
      
   // now, we can take smallest positive distance.
   
   // Initialize
   //
   G4double      distance = kInfinity;   

   // find intersections and choose nearest one.
   //
   G4VTwistSurface *surfaces[6];
   surfaces[0] = fLowerEndcap;
   surfaces[1] = fUpperEndcap;
   surfaces[2] = fLatterTwisted;
   surfaces[3] = fFormerTwisted;
   surfaces[4] = fInnerHype;
   surfaces[5] = fOuterHype;
   
   G4ThreeVector xx;
   G4ThreeVector bestxx;
   G4int i;
   for (i=0; i< 6; i++)
   {
      G4double tmpdistance = surfaces[i]->DistanceToIn(p, v, xx);
      if (tmpdistance < distance)
      {
         distance = tmpdistance;
         bestxx = xx;
      }
   }
   *tmpdist = distance;

   return fLastDistanceToInWithV.value;
}
 
//=====================================================================
//* DistanceToIn (p) --------------------------------------------------

G4double G4TwistedTubs::DistanceToIn (const G4ThreeVector& p) const
{
   // DistanceToIn(p):
   // Calculate distance to surface of shape from `outside',
   // allowing for tolerance
   
   //
   // checking last value
   //
   
   G4ThreeVector *tmpp;
   G4double      *tmpdist;
   if (fLastDistanceToIn.p == p)
   {
     return fLastDistanceToIn.value;
   }
   else
   {
      tmpp    = const_cast<G4ThreeVector*>(&(fLastDistanceToIn.p));
      tmpdist = const_cast<G4double*>(&(fLastDistanceToIn.value));
      tmpp->set(p.x(), p.y(), p.z());
   }

   //
   // Calculate DistanceToIn(p) 
   //
   
   EInside currentside = Inside(p);

   switch (currentside)
   {
      case (kInside) :
      {}
      case (kSurface) :
      {
         *tmpdist = 0.;
         return fLastDistanceToIn.value;
      }
      case (kOutside) :
      {
         // Initialize
         G4double      distance = kInfinity;   

         // find intersections and choose nearest one.
         G4VTwistSurface *surfaces[6];
         surfaces[0] = fLowerEndcap;
         surfaces[1] = fUpperEndcap;
         surfaces[2] = fLatterTwisted;
         surfaces[3] = fFormerTwisted;
         surfaces[4] = fInnerHype;
         surfaces[5] = fOuterHype;

         G4int i;
         G4ThreeVector xx;
         G4ThreeVector bestxx;
         for (i=0; i< 6; i++)
         {
            G4double tmpdistance = surfaces[i]->DistanceTo(p, xx);
            if (tmpdistance < distance)
            {
               distance = tmpdistance;
               bestxx = xx;
            }
         }
         *tmpdist = distance;
         return fLastDistanceToIn.value;
      }
      default :
      {
         G4Exception("G4TwistedTubs::DistanceToIn(p)", "GeomSolids0003",
                     FatalException, "Unknown point location!");
      }
   } // switch end

   return kInfinity;
}

//=====================================================================
//* DistanceToOut (p, v) ----------------------------------------------

G4double G4TwistedTubs::DistanceToOut( const G4ThreeVector& p,
                                       const G4ThreeVector& v,
                                       const G4bool calcNorm,
                                       G4bool *validNorm,
                                       G4ThreeVector *norm ) const
{
   // DistanceToOut (p, v):
   // Calculate distance to surface of shape from `inside'
   // along with the v, allowing for tolerance.
   // The function returns kInfinity if no intersection or
   // just grazing within tolerance.

   //
   // checking last value
   //
   
   G4ThreeVector *tmpp;
   G4ThreeVector *tmpv;
   G4double      *tmpdist;
   if ((fLastDistanceToOutWithV.p == p) && (fLastDistanceToOutWithV.vec == v) )
   {
     return fLastDistanceToOutWithV.value;
   }
   else
   {
      tmpp    = const_cast<G4ThreeVector*>(&(fLastDistanceToOutWithV.p));
      tmpv    = const_cast<G4ThreeVector*>(&(fLastDistanceToOutWithV.vec));
      tmpdist = const_cast<G4double*>(&(fLastDistanceToOutWithV.value));
      tmpp->set(p.x(), p.y(), p.z());
      tmpv->set(v.x(), v.y(), v.z());
   }

   //
   // Calculate DistanceToOut(p,v)
   //
   
   EInside currentside = Inside(p);

   if (currentside == kOutside)
   {
   }
   else
   {
     if (currentside == kSurface)
     {
       // particle is just on a boundary.
       // If the particle is exiting from the volume, return 0.
       //
       G4ThreeVector normal = SurfaceNormal(p);
       G4VTwistSurface *blockedsurface = fLastNormal.surface[0];
       if (normal*v > 0)
       {
         if (calcNorm)
         {
           *norm = (blockedsurface->GetNormal(p, true));
           *validNorm = blockedsurface->IsValidNorm();
         }
         *tmpdist = 0.;
         return fLastDistanceToOutWithV.value;
       }
     }
   }
      
   // now, we can take smallest positive distance.
   
   // Initialize
   //
   G4double      distance = kInfinity;
       
   // find intersections and choose nearest one.
   //
   G4VTwistSurface *surfaces[6];
   surfaces[0] = fLatterTwisted;
   surfaces[1] = fFormerTwisted;
   surfaces[2] = fInnerHype;
   surfaces[3] = fOuterHype;
   surfaces[4] = fLowerEndcap;
   surfaces[5] = fUpperEndcap;
   
   G4int i;
   G4int besti = -1;
   G4ThreeVector xx;
   G4ThreeVector bestxx;
   for (i=0; i< 6; i++)
   {
      G4double tmpdistance = surfaces[i]->DistanceToOut(p, v, xx);
      if (tmpdistance < distance)
      {
         distance = tmpdistance;
         bestxx = xx; 
         besti = i;
      }
   }

   if (calcNorm)
   {
      if (besti != -1)
      {
         *norm = (surfaces[besti]->GetNormal(p, true));
         *validNorm = surfaces[besti]->IsValidNorm();
      }
   }

   *tmpdist = distance;

   return fLastDistanceToOutWithV.value;
}


//=====================================================================
//* DistanceToOut (p) ----------------------------------------------

G4double G4TwistedTubs::DistanceToOut( const G4ThreeVector& p ) const
{
   // DistanceToOut(p):
   // Calculate distance to surface of shape from `inside', 
   // allowing for tolerance

   //
   // checking last value
   //
   
   G4ThreeVector *tmpp;
   G4double      *tmpdist;
   if (fLastDistanceToOut.p == p)
   {
      return fLastDistanceToOut.value;
   }
   else
   {
      tmpp    = const_cast<G4ThreeVector*>(&(fLastDistanceToOut.p));
      tmpdist = const_cast<G4double*>(&(fLastDistanceToOut.value));
      tmpp->set(p.x(), p.y(), p.z());
   }
   
   //
   // Calculate DistanceToOut(p)
   //
   
   EInside currentside = Inside(p);

   switch (currentside)
   {
      case (kOutside) :
      {
      }
      case (kSurface) :
      {
        *tmpdist = 0.;
         return fLastDistanceToOut.value;
      }
      case (kInside) :
      {
         // Initialize
         G4double      distance = kInfinity;
   
         // find intersections and choose nearest one.
         G4VTwistSurface *surfaces[6];
         surfaces[0] = fLatterTwisted;
         surfaces[1] = fFormerTwisted;
         surfaces[2] = fInnerHype;
         surfaces[3] = fOuterHype;
         surfaces[4] = fLowerEndcap;
         surfaces[5] = fUpperEndcap;

         G4int i;
         G4ThreeVector xx;
         G4ThreeVector bestxx;
         for (i=0; i< 6; i++)
         {
            G4double tmpdistance = surfaces[i]->DistanceTo(p, xx);
            if (tmpdistance < distance)
            {
               distance = tmpdistance;
               bestxx = xx;
            }
         }
         *tmpdist = distance;
   
         return fLastDistanceToOut.value;
      }
      default :
      {
         G4Exception("G4TwistedTubs::DistanceToOut(p)", "GeomSolids0003",
                     FatalException, "Unknown point location!");
      }
   } // switch end

   return 0;
}

//=====================================================================
//* StreamInfo --------------------------------------------------------

std::ostream& G4TwistedTubs::StreamInfo(std::ostream& os) const
{
  //
  // Stream object contents to an output stream
  //
  G4int oldprc = os.precision(16);
  os << "-----------------------------------------------------------\n"
     << "    *** Dump for solid - " << GetName() << " ***\n"
     << "    ===================================================\n"
     << " Solid type: G4TwistedTubs\n"
     << " Parameters: \n"
     << "    -ve end Z              : " << fEndZ[0]/mm << " mm \n"
     << "    +ve end Z              : " << fEndZ[1]/mm << " mm \n"
     << "    inner end radius(-ve z): " << fEndInnerRadius[0]/mm << " mm \n"
     << "    inner end radius(+ve z): " << fEndInnerRadius[1]/mm << " mm \n"
     << "    outer end radius(-ve z): " << fEndOuterRadius[0]/mm << " mm \n"
     << "    outer end radius(+ve z): " << fEndOuterRadius[1]/mm << " mm \n"
     << "    inner radius (z=0)     : " << fInnerRadius/mm << " mm \n"
     << "    outer radius (z=0)     : " << fOuterRadius/mm << " mm \n"
     << "    twisted angle          : " << fPhiTwist/degree << " degrees \n"
     << "    inner stereo angle     : " << fInnerStereo/degree << " degrees \n"
     << "    outer stereo angle     : " << fOuterStereo/degree << " degrees \n"
     << "    phi-width of a piece   : " << fDPhi/degree << " degrees \n"
     << "-----------------------------------------------------------\n";
  os.precision(oldprc);

  return os;
}


//=====================================================================
//* DiscribeYourselfTo ------------------------------------------------

void G4TwistedTubs::DescribeYourselfTo (G4VGraphicsScene& scene) const 
{
  scene.AddSolid (*this);
}

//=====================================================================
//* GetExtent ---------------------------------------------------------

G4VisExtent G4TwistedTubs::GetExtent() const 
{
  // Define the sides of the box into which the G4Tubs instance would fit.

  G4double maxEndOuterRad = (fEndOuterRadius[0] > fEndOuterRadius[1] ? 0 : 1);
  return G4VisExtent( -maxEndOuterRad, maxEndOuterRad, 
                      -maxEndOuterRad, maxEndOuterRad, 
                      -fZHalfLength, fZHalfLength );
}

//=====================================================================
//* CreatePolyhedron --------------------------------------------------

G4Polyhedron* G4TwistedTubs::CreatePolyhedron () const 
{
  // number of meshes
  //
  G4double dA = std::max(fDPhi,fPhiTwist);
  const G4int k =
    G4int(G4Polyhedron::GetNumberOfRotationSteps() * dA / twopi) + 2;
  const G4int n =
    G4int(G4Polyhedron::GetNumberOfRotationSteps() * fPhiTwist / twopi) + 2;

  const G4int nnodes = 4*(k-1)*(n-2) + 2*k*k ;
  const G4int nfaces = 4*(k-1)*(n-1) + 2*(k-1)*(k-1) ;

  G4Polyhedron *ph=new G4Polyhedron;
  typedef G4double G4double3[3];
  typedef G4int G4int4[4];
  G4double3* xyz = new G4double3[nnodes];  // number of nodes 
  G4int4*  faces = new G4int4[nfaces] ;    // number of faces
  fLowerEndcap->GetFacets(k,k,xyz,faces,0) ;
  fUpperEndcap->GetFacets(k,k,xyz,faces,1) ;
  fInnerHype->GetFacets(k,n,xyz,faces,2) ;
  fFormerTwisted->GetFacets(k,n,xyz,faces,3) ;
  fOuterHype->GetFacets(k,n,xyz,faces,4) ;
  fLatterTwisted->GetFacets(k,n,xyz,faces,5) ;

  ph->createPolyhedron(nnodes,nfaces,xyz,faces);

  delete[] xyz;
  delete[] faces;

  return ph;
}

//=====================================================================
//* GetPolyhedron -----------------------------------------------------

G4Polyhedron* G4TwistedTubs::GetPolyhedron () const
{
  if (!fpPolyhedron ||
      fRebuildPolyhedron ||
      fpPolyhedron->GetNumberOfRotationStepsAtTimeOfCreation() !=
      fpPolyhedron->GetNumberOfRotationSteps())
  {
    G4AutoLock l(&polyhedronMutex);
    delete fpPolyhedron;
    fpPolyhedron = CreatePolyhedron();
    fRebuildPolyhedron = false;
    l.unlock();
  }
  return fpPolyhedron;
}

//=====================================================================
//* CreateSurfaces ----------------------------------------------------

void G4TwistedTubs::CreateSurfaces() 
{
   // create 6 surfaces of TwistedTub

   G4ThreeVector x0(0, 0, fEndZ[0]);
   G4ThreeVector n (0, 0, -1);

   fLowerEndcap = new G4TwistTubsFlatSide("LowerEndcap",
                                    fEndInnerRadius, fEndOuterRadius,
                                    fDPhi, fEndPhi, fEndZ, -1) ;

   fUpperEndcap = new G4TwistTubsFlatSide("UpperEndcap",  
                                    fEndInnerRadius, fEndOuterRadius,
                                    fDPhi, fEndPhi, fEndZ, 1) ;

   G4RotationMatrix    rotHalfDPhi;
   rotHalfDPhi.rotateZ(0.5*fDPhi);

   fLatterTwisted = new G4TwistTubsSide("LatterTwisted",
                                         fEndInnerRadius, fEndOuterRadius,
                                         fDPhi, fEndPhi, fEndZ, 
                                         fInnerRadius, fOuterRadius, fKappa,
                                         1 ) ; 
   fFormerTwisted = new G4TwistTubsSide("FormerTwisted", 
                                         fEndInnerRadius, fEndOuterRadius,
                                         fDPhi, fEndPhi, fEndZ, 
                                         fInnerRadius, fOuterRadius, fKappa,
                                         -1 ) ; 

   fInnerHype = new G4TwistTubsHypeSide("InnerHype",
                                        fEndInnerRadius, fEndOuterRadius,
                                        fDPhi, fEndPhi, fEndZ, 
                                        fInnerRadius, fOuterRadius,fKappa,
                                        fTanInnerStereo, fTanOuterStereo, -1) ;
   fOuterHype = new G4TwistTubsHypeSide("OuterHype", 
                                        fEndInnerRadius, fEndOuterRadius,
                                        fDPhi, fEndPhi, fEndZ, 
                                        fInnerRadius, fOuterRadius,fKappa,
                                        fTanInnerStereo, fTanOuterStereo, 1) ;


   // set neighbour surfaces
   //
   fLowerEndcap->SetNeighbours(fInnerHype, fLatterTwisted,
                               fOuterHype, fFormerTwisted);
   fUpperEndcap->SetNeighbours(fInnerHype, fLatterTwisted,
                               fOuterHype, fFormerTwisted);
   fLatterTwisted->SetNeighbours(fInnerHype, fLowerEndcap,
                                 fOuterHype, fUpperEndcap);
   fFormerTwisted->SetNeighbours(fInnerHype, fLowerEndcap,
                                 fOuterHype, fUpperEndcap);
   fInnerHype->SetNeighbours(fLatterTwisted, fLowerEndcap,
                             fFormerTwisted, fUpperEndcap);
   fOuterHype->SetNeighbours(fLatterTwisted, fLowerEndcap,
                             fFormerTwisted, fUpperEndcap);
}


//=====================================================================
//* GetEntityType -----------------------------------------------------

G4GeometryType G4TwistedTubs::GetEntityType() const
{
  return G4String("G4TwistedTubs");
}

//=====================================================================
//* Clone -------------------------------------------------------------

G4VSolid* G4TwistedTubs::Clone() const
{
  return new G4TwistedTubs(*this);
}

//=====================================================================
//* GetCubicVolume ----------------------------------------------------

G4double G4TwistedTubs::GetCubicVolume()
{
  if(fCubicVolume != 0.) {;}
  else   { fCubicVolume = fDPhi*fZHalfLength*(fOuterRadius*fOuterRadius
                                             -fInnerRadius*fInnerRadius); }
  return fCubicVolume;
}

//=====================================================================
//* GetSurfaceArea ----------------------------------------------------

G4double G4TwistedTubs::GetSurfaceArea()
{
  if(fSurfaceArea != 0.) {;}
  else   { fSurfaceArea = G4VSolid::GetSurfaceArea(); }
  return fSurfaceArea;
}

//=====================================================================
//* GetPointOnSurface -------------------------------------------------

G4ThreeVector G4TwistedTubs::GetPointOnSurface() const
{

  G4double  z = G4RandFlat::shoot(fEndZ[0],fEndZ[1]);
  G4double phi , phimin, phimax ;
  G4double x   , xmin,   xmax ;
  G4double r   , rmin,   rmax ;

  G4double a1 = fOuterHype->GetSurfaceArea() ;
  G4double a2 = fInnerHype->GetSurfaceArea() ;
  G4double a3 = fLatterTwisted->GetSurfaceArea() ;
  G4double a4 = fFormerTwisted->GetSurfaceArea() ;
  G4double a5 = fLowerEndcap->GetSurfaceArea()  ;
  G4double a6 = fUpperEndcap->GetSurfaceArea() ;

  G4double chose = G4RandFlat::shoot(0.,a1 + a2 + a3 + a4 + a5 + a6) ;

  if(chose < a1)
  {

    phimin = fOuterHype->GetBoundaryMin(z) ;
    phimax = fOuterHype->GetBoundaryMax(z) ;
    phi = G4RandFlat::shoot(phimin,phimax) ;

    return fOuterHype->SurfacePoint(phi,z,true) ;

  }
  else if ( (chose >= a1) && (chose < a1 + a2 ) )
  {

    phimin = fInnerHype->GetBoundaryMin(z) ;
    phimax = fInnerHype->GetBoundaryMax(z) ;
    phi = G4RandFlat::shoot(phimin,phimax) ;

    return fInnerHype->SurfacePoint(phi,z,true) ;

  }
  else if ( (chose >= a1 + a2 ) && (chose < a1 + a2 + a3 ) ) 
  {

    xmin = fLatterTwisted->GetBoundaryMin(z) ; 
    xmax = fLatterTwisted->GetBoundaryMax(z) ;
    x = G4RandFlat::shoot(xmin,xmax) ;
    
    return fLatterTwisted->SurfacePoint(x,z,true) ;

  }
  else if ( (chose >= a1 + a2 + a3  ) && (chose < a1 + a2 + a3 + a4  ) )
  {

    xmin = fFormerTwisted->GetBoundaryMin(z) ; 
    xmax = fFormerTwisted->GetBoundaryMax(z) ;
    x = G4RandFlat::shoot(xmin,xmax) ;

    return fFormerTwisted->SurfacePoint(x,z,true) ;
   }
  else if( (chose >= a1 + a2 + a3 + a4  )&&(chose < a1 + a2 + a3 + a4 + a5 ) )
  {
    rmin = GetEndInnerRadius(0) ;
    rmax = GetEndOuterRadius(0) ;
    r = std::sqrt(G4RandFlat::shoot()*(sqr(rmax)-sqr(rmin))+sqr(rmin));

    phimin = fLowerEndcap->GetBoundaryMin(r) ; 
    phimax = fLowerEndcap->GetBoundaryMax(r) ;
    phi    = G4RandFlat::shoot(phimin,phimax) ;

    return fLowerEndcap->SurfacePoint(phi,r,true) ;
  }
  else
  {
    rmin = GetEndInnerRadius(1) ;
    rmax = GetEndOuterRadius(1) ;
    r = rmin + (rmax-rmin)*std::sqrt(G4RandFlat::shoot());

    phimin = fUpperEndcap->GetBoundaryMin(r) ; 
    phimax = fUpperEndcap->GetBoundaryMax(r) ;
    phi    = G4RandFlat::shoot(phimin,phimax) ;

    return fUpperEndcap->SurfacePoint(phi,r,true) ;
  }
}