G4VTwistedFaceted.cc

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//
// G4VTwistedFaceted implementation
//
// Author: Oliver Link (CERN), 27.10.2004 - Created
// --------------------------------------------------------------------
 
#include "G4VTwistedFaceted.hh"
 
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4VoxelLimits.hh"
#include "G4AffineTransform.hh"
#include "G4BoundingEnvelope.hh"
#include "G4SolidExtentList.hh"
#include "G4ClippablePolygon.hh"
#include "G4VPVParameterisation.hh"
#include "G4GeometryTolerance.hh"
 
#include "G4VGraphicsScene.hh"
#include "G4Polyhedron.hh"
#include "G4VisExtent.hh"
 
#include "G4QuickRand.hh"
 
#include "G4AutoLock.hh"
 
namespace
{
  G4Mutex polyhedronMutex = G4MUTEX_INITIALIZER;
  G4Mutex vtwMutex = G4MUTEX_INITIALIZER;
}
 
 
//=====================================================================
//* constructors ------------------------------------------------------
 
G4VTwistedFaceted::
G4VTwistedFaceted( const G4String& pname,     // Name of instance
                         G4double  PhiTwist,  // twist angle
                         G4double  pDz,       // half z length
                         G4double  pTheta, // direction between end planes
                         G4double  pPhi,   // defined by polar and azim. 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 
  : G4VSolid(pname),
    fLowerEndcap(nullptr), fUpperEndcap(nullptr), fSide0(nullptr),
    fSide90(nullptr), fSide180(nullptr), fSide270(nullptr)
{
 
  G4double pDytmp ;
  G4double fDxUp ;
  G4double fDxDown ;
 
  fDx1 = pDx1 ;
  fDx2 = pDx2 ;
  fDx3 = pDx3 ;
  fDx4 = pDx4 ;
  fDy1 = pDy1 ;
  fDy2 = pDy2 ;
  fDz  = pDz  ;
 
  G4double kAngTolerance
    = G4GeometryTolerance::GetInstance()->GetAngularTolerance();
 
  // maximum values
  //
  fDxDown = ( fDx1 > fDx2 ? fDx1 : fDx2 ) ;
  fDxUp   = ( fDx3 > fDx4 ? fDx3 : fDx4 ) ;
  fDx     = ( fDxUp > fDxDown ? fDxUp : fDxDown ) ;
  fDy     = ( fDy1 > fDy2 ? fDy1 : fDy2 ) ;
  
  // planarity check
  //
  if ( fDx1 != fDx2 && fDx3 != fDx4 )
  {
    pDytmp = fDy1 * ( fDx3 - fDx4 ) / ( fDx1 - fDx2 ) ;
    if ( std::fabs(pDytmp - fDy2) > kCarTolerance )
    {
      std::ostringstream message;
      message << "Not planar surface in untwisted Trapezoid: "
              << GetName() << G4endl
              << "fDy2 is " << fDy2 << " but should be "
              << pDytmp << ".";
      G4Exception("G4VTwistedFaceted::G4VTwistedFaceted()", "GeomSolids0002",
                  FatalErrorInArgument, message);
    }
  }
 
#ifdef G4TWISTDEBUG
  if ( fDx1 == fDx2 && fDx3 == fDx4 )
  { 
      G4cout << "Trapezoid is a box" << G4endl ;
  }
  
#endif
 
  if ( (  fDx1 == fDx2 && fDx3 != fDx4 ) || ( fDx1 != fDx2 && fDx3 == fDx4 ) )
  {
    std::ostringstream message;
    message << "Not planar surface in untwisted Trapezoid: "
            << GetName() << G4endl
            << "One endcap is rectangular, the other is a trapezoid." << G4endl
            << "For planarity reasons they have to be rectangles or trapezoids "
            << "on both sides.";
    G4Exception("G4VTwistedFaceted::G4VTwistedFaceted()", "GeomSolids0002",
                FatalErrorInArgument, message);
  }
 
  // twist angle
  //
  fPhiTwist = PhiTwist ;
 
  // tilt angle
  //
  fAlph = pAlph ; 
  fTAlph = std::tan(fAlph) ;
  
  fTheta = pTheta ;
  fPhi   = pPhi ;
 
  // dx in surface equation
  //
  fdeltaX = 2 * fDz * std::tan(fTheta) * std::cos(fPhi)  ;
 
  // dy in surface equation
  //
  fdeltaY = 2 * fDz * std::tan(fTheta) * std::sin(fPhi)  ;
 
  if  ( ( fDx1  <= 2*kCarTolerance)
         || ( fDx2  <= 2*kCarTolerance)
         || ( fDx3  <= 2*kCarTolerance)
         || ( fDx4  <= 2*kCarTolerance)
         || ( fDy1  <= 2*kCarTolerance)
         || ( fDy2  <= 2*kCarTolerance)
         || ( fDz   <= 2*kCarTolerance) 
         || ( std::fabs(fPhiTwist) <= 2*kAngTolerance )
         || ( std::fabs(fPhiTwist) >= pi/2 )
         || ( std::fabs(fAlph) >= pi/2 )
         || fTheta >= pi/2 || fTheta < 0 
      )
  {
    std::ostringstream message;
    message << "Invalid dimensions. Too small, or twist angle too big: "
            << GetName() << G4endl
            << "fDx 1-4 = " << fDx1/cm << ", " << fDx2/cm << ", "
            << fDx3/cm << ", " << fDx4/cm << " cm" << G4endl 
            << "fDy 1-2 = " << fDy1/cm << ", " << fDy2/cm << ", "
            << " cm" << G4endl 
            << "fDz = " << fDz/cm << " cm" << G4endl 
            << " twistangle " << fPhiTwist/deg << " deg" << G4endl 
            << " phi,theta = " << fPhi/deg << ", "  << fTheta/deg << " deg";
    G4Exception("G4TwistedTrap::G4VTwistedFaceted()",
                "GeomSolids0002", FatalErrorInArgument, message);
  }
  CreateSurfaces();
}
 
 
//=====================================================================
//* Fake default constructor ------------------------------------------
 
G4VTwistedFaceted::G4VTwistedFaceted( __void__& a )
  : G4VSolid(a),
    fLowerEndcap(nullptr), fUpperEndcap(nullptr),
    fSide0(nullptr), fSide90(nullptr), fSide180(nullptr), fSide270(nullptr)
{
}
 
 
//=====================================================================
//* destructor --------------------------------------------------------
 
G4VTwistedFaceted::~G4VTwistedFaceted()
{
  delete fLowerEndcap ; 
  delete fUpperEndcap ; 
 
  delete fSide0   ; 
  delete fSide90  ; 
  delete fSide180 ; 
  delete fSide270 ; 
  delete fpPolyhedron; fpPolyhedron = nullptr;
}
 
 
//=====================================================================
//* Copy constructor --------------------------------------------------
 
G4VTwistedFaceted::G4VTwistedFaceted(const G4VTwistedFaceted& rhs)
  : G4VSolid(rhs),
    fCubicVolume(rhs.fCubicVolume), fSurfaceArea(rhs.fSurfaceArea),
    fTheta(rhs.fTheta), fPhi(rhs.fPhi),
    fDy1(rhs.fDy1), fDx1(rhs.fDx1), fDx2(rhs.fDx2), fDy2(rhs.fDy2),
    fDx3(rhs.fDx3), fDx4(rhs.fDx4), fDz(rhs.fDz), fDx(rhs.fDx), fDy(rhs.fDy),
    fAlph(rhs.fAlph), fTAlph(rhs.fTAlph), fdeltaX(rhs.fdeltaX),
    fdeltaY(rhs.fdeltaY), fPhiTwist(rhs.fPhiTwist), fLowerEndcap(nullptr),
    fUpperEndcap(nullptr), fSide0(nullptr), fSide90(nullptr), fSide180(nullptr), fSide270(nullptr)
{
  CreateSurfaces();
}
 
 
//=====================================================================
//* Assignment operator -----------------------------------------------
 
G4VTwistedFaceted& G4VTwistedFaceted::operator = (const G4VTwistedFaceted& rhs) 
{
   // Check assignment to self
   //
   if (this == &rhs)  { return *this; }
 
   // Copy base class data
   //
   G4VSolid::operator=(rhs);
 
   // Copy data
   //
   fTheta = rhs.fTheta; fPhi = rhs.fPhi;
   fDy1= rhs.fDy1; fDx1= rhs.fDx1; fDx2= rhs.fDx2; fDy2= rhs.fDy2;
   fDx3= rhs.fDx3; fDx4= rhs.fDx4; fDz= rhs.fDz; fDx= rhs.fDx; fDy= rhs.fDy;
   fAlph= rhs.fAlph; fTAlph= rhs.fTAlph; fdeltaX= rhs.fdeltaX;
   fdeltaY= rhs.fdeltaY; fPhiTwist= rhs.fPhiTwist; fLowerEndcap= nullptr;
   fUpperEndcap= nullptr; fSide0= nullptr; fSide90= nullptr; fSide180= nullptr; fSide270= nullptr;
   fCubicVolume= rhs.fCubicVolume; fSurfaceArea= rhs.fSurfaceArea;
   fRebuildPolyhedron = false;
   delete fpPolyhedron; fpPolyhedron = nullptr;
 
   CreateSurfaces();
 
   return *this;
}
 
 
//=====================================================================
//* ComputeDimensions -------------------------------------------------
 
void G4VTwistedFaceted::ComputeDimensions(G4VPVParameterisation* ,
                                          const G4int ,
                                          const G4VPhysicalVolume* )
{
  G4Exception("G4VTwistedFaceted::ComputeDimensions()",
              "GeomSolids0001", FatalException,
              "G4VTwistedFaceted does not support Parameterisation.");
}
 
 
//=====================================================================
//* Extent ------------------------------------------------------------
 
void G4VTwistedFaceted::BoundingLimits(G4ThreeVector& pMin,
                                       G4ThreeVector& pMax) const
{
  G4double cosPhi = std::cos(fPhi);
  G4double sinPhi = std::sin(fPhi);
  G4double tanTheta = std::tan(fTheta);
  G4double tanAlpha = fTAlph;
 
  G4double xmid1 = fDy1*tanAlpha;
  G4double x1 = std::abs(xmid1 + fDx1);
  G4double x2 = std::abs(xmid1 - fDx1);
  G4double x3 = std::abs(xmid1 + fDx2);
  G4double x4 = std::abs(xmid1 - fDx2);
  G4double xmax1 = std::max(std::max(std::max(x1, x2), x3), x4);
  G4double rmax1 = std::sqrt(xmax1*xmax1 + fDy1*fDy1);
 
  G4double xmid2 = fDy2*tanAlpha;
  G4double x5 = std::abs(xmid2 + fDx3);
  G4double x6 = std::abs(xmid2 - fDx3);
  G4double x7 = std::abs(xmid2 + fDx4);
  G4double x8 = std::abs(xmid2 - fDx4);
  G4double xmax2 = std::max(std::max(std::max(x5, x6), x7), x8);
  G4double rmax2 = std::sqrt(xmax2*xmax2 + fDy2*fDy2);
 
  G4double x0 = fDz*tanTheta*cosPhi;
  G4double y0 = fDz*tanTheta*sinPhi;
  G4double xmin = std::min(-x0 - rmax1, x0 - rmax2);
  G4double ymin = std::min(-y0 - rmax1, y0 - rmax2);
  G4double xmax = std::max(-x0 + rmax1, x0 + rmax2);
  G4double ymax = std::max(-y0 + rmax1, y0 + rmax2);
  pMin.set(xmin, ymin,-fDz);
  pMax.set(xmax, ymax, fDz);
}
 
 
//=====================================================================
//* CalculateExtent ---------------------------------------------------
 
G4bool
G4VTwistedFaceted::CalculateExtent( const EAxis              pAxis,
                                    const G4VoxelLimits&     pVoxelLimit,
                                    const G4AffineTransform& pTransform,
                                          G4double&          pMin,
                                          G4double&          pMax ) const
{
  G4ThreeVector bmin, bmax;
 
  // Get bounding box
  BoundingLimits(bmin,bmax);
 
  // Find extent
  G4BoundingEnvelope bbox(bmin,bmax);
  return bbox.CalculateExtent(pAxis,pVoxelLimit,pTransform,pMin,pMax);
}
 
 
//=====================================================================
//* Inside ------------------------------------------------------------
 
EInside G4VTwistedFaceted::Inside(const G4ThreeVector& p) const
{
 
   EInside tmpin = kOutside ;
 
   G4double phi = p.z()/(2*fDz) * fPhiTwist ;  // rotate the point to z=0
   G4double cphi = std::cos(-phi) ;
   G4double sphi = std::sin(-phi) ;
 
   G4double px  = p.x() + fdeltaX * ( -phi/fPhiTwist) ;  // shift
   G4double py  = p.y() + fdeltaY * ( -phi/fPhiTwist) ;
   G4double pz  = p.z() ;
 
   G4double posx = px * cphi - py * sphi   ;  // rotation
   G4double posy = px * sphi + py * cphi   ;
   G4double posz = pz  ;
 
   G4double xMin = Xcoef(posy,phi,fTAlph) - 2*Xcoef(posy,phi,0.) ; 
   G4double xMax = Xcoef(posy,phi,fTAlph) ;  
 
   G4double yMax = GetValueB(phi)/2. ;  // b(phi)/2 is limit
   G4double yMin = -yMax ;
 
#ifdef G4TWISTDEBUG
 
   G4cout << "inside called: p = " << p << G4endl ; 
   G4cout << "fDx1 = " << fDx1 << G4endl ;
   G4cout << "fDx2 = " << fDx2 << G4endl ;
   G4cout << "fDx3 = " << fDx3 << G4endl ;
   G4cout << "fDx4 = " << fDx4 << G4endl ;
 
   G4cout << "fDy1 = " << fDy1 << G4endl ;
   G4cout << "fDy2 = " << fDy2 << G4endl ;
 
   G4cout << "fDz  = " << fDz  << G4endl ;
 
   G4cout << "Tilt angle alpha = " << fAlph << G4endl ;
   G4cout << "phi,theta = " << fPhi << " , " << fTheta << G4endl ;
 
   G4cout << "Twist angle = " << fPhiTwist << G4endl ;
 
   G4cout << "posx = " << posx << G4endl ;
   G4cout << "posy = " << posy << G4endl ;
   G4cout << "xMin = " << xMin << G4endl ;
   G4cout << "xMax = " << xMax << G4endl ;
   G4cout << "yMin = " << yMin << G4endl ;
   G4cout << "yMax = " << yMax << G4endl ;
 
#endif 
 
 
  if ( posx <= xMax - kCarTolerance*0.5
    && posx >= xMin + kCarTolerance*0.5 )
  {
    if ( posy <= yMax - kCarTolerance*0.5
      && posy >= yMin + kCarTolerance*0.5 )
    {
      if      (std::fabs(posz) <= fDz - kCarTolerance*0.5 )
      {
        tmpin = kInside ;
      }
      else if (std::fabs(posz) <= fDz + kCarTolerance*0.5 )
      {
        tmpin = kSurface ;
      }
    }
    else if ( posy <= yMax + kCarTolerance*0.5
           && posy >= yMin - kCarTolerance*0.5 )
    {
      if (std::fabs(posz) <= fDz + kCarTolerance*0.5 ) { tmpin = kSurface ; }
    }
  }
  else if ( posx <= xMax + kCarTolerance*0.5
         && posx >= xMin - kCarTolerance*0.5 )
  {
    if ( posy <= yMax + kCarTolerance*0.5
      && posy >= yMin - kCarTolerance*0.5 )
    {
      if (std::fabs(posz) <= fDz + kCarTolerance*0.5) { tmpin = kSurface ; }
    }
  }
 
#ifdef G4TWISTDEBUG
  G4cout << "inside = " << tmpin << G4endl ;
#endif
 
  return tmpin;
 
}
 
 
//=====================================================================
//* SurfaceNormal -----------------------------------------------------
 
G4ThreeVector G4VTwistedFaceted::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?
   //
 
 
   G4double distance = kInfinity;
 
   G4VTwistSurface* surfaces[6];
 
   surfaces[0] = fSide0 ;
   surfaces[1] = fSide90 ;
   surfaces[2] = fSide180 ;
   surfaces[3] = fSide270 ;
   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; 
      }
   }
 
   return surfaces[besti]->GetNormal(bestxx, true);
}
 
 
//=====================================================================
//* DistanceToIn (p, v) -----------------------------------------------
 
G4double G4VTwistedFaceted::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.
 
   //
   // 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)
     {
       return 0;
     } 
   }
      
   // now, we can take smallest positive distance.
   
   // Initialize
   //
   G4double distance = kInfinity;   
 
   // Find intersections and choose nearest one
   //
   G4VTwistSurface *surfaces[6];
 
   surfaces[0] = fSide0;
   surfaces[1] = fSide90 ;
   surfaces[2] = fSide180 ;
   surfaces[3] = fSide270 ;
   surfaces[4] = fLowerEndcap;
   surfaces[5] = fUpperEndcap;
   
   G4ThreeVector xx;
   G4ThreeVector bestxx;
   for (const auto & surface : surfaces)
   {
#ifdef G4TWISTDEBUG
      G4cout << G4endl << "surface " << &surface - &*surfaces << ": " << G4endl << G4endl ;
#endif
      G4double tmpdistance = surface->DistanceToIn(p, v, xx);
#ifdef G4TWISTDEBUG
      G4cout << "Solid DistanceToIn : distance = " << tmpdistance << G4endl ; 
      G4cout << "intersection point = " << xx << G4endl ;
#endif 
      if (tmpdistance < distance)
      {
         distance = tmpdistance;
         bestxx = xx;
      }
   }
 
#ifdef G4TWISTDEBUG
   G4cout << "best distance = " << distance << G4endl ;
#endif
 
   // timer.Stop();
   return distance;
}
 
 
//=====================================================================
//* DistanceToIn (p) --------------------------------------------------
 
G4double G4VTwistedFaceted::DistanceToIn (const G4ThreeVector& p) const
{
   // DistanceToIn(p):
   // Calculate distance to surface of shape from `outside',
   // allowing for tolerance
   //
   
   //
   // Calculate DistanceToIn(p) 
   //
   
   EInside currentside = Inside(p);
 
   switch (currentside)
   {
      case (kInside) :
      {
      }
 
      case (kSurface) :
      {
         return 0;
      }
 
      case (kOutside) :
      {
         // Initialize
         //
         G4double distance = kInfinity;   
 
         // Find intersections and choose nearest one
         //
         G4VTwistSurface* surfaces[6];
 
         surfaces[0] = fSide0;
         surfaces[1] = fSide90 ;
         surfaces[2] = fSide180 ;
         surfaces[3] = fSide270 ;
         surfaces[4] = fLowerEndcap;
         surfaces[5] = fUpperEndcap;
 
         G4ThreeVector xx;
         G4ThreeVector bestxx;
         for (const auto & surface : surfaces)
         {
            G4double tmpdistance = surface->DistanceTo(p, xx);
            if (tmpdistance < distance)
            {
               distance = tmpdistance;
               bestxx = xx;
            }
         }
         return distance;
      }
 
      default:
      {
         G4Exception("G4VTwistedFaceted::DistanceToIn(p)", "GeomSolids0003",
                     FatalException, "Unknown point location!");
      }
   } // switch end
 
   return 0.;
}
 
 
//=====================================================================
//* DistanceToOut (p, v) ----------------------------------------------
 
G4double
G4VTwistedFaceted::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.
 
   //
   // 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);
      if (normal*v > 0)
      {
            if (calcNorm)
            {
               *norm = normal;
               *validNorm = true;
            }
            // timer.Stop();
            return 0;
      }
   }
      
   // now, we can take smallest positive distance.
   
   // Initialize
   G4double distance = kInfinity;
       
   // find intersections and choose nearest one.
   G4VTwistSurface *surfaces[6];
 
   surfaces[0] = fSide0;
   surfaces[1] = fSide90 ;
   surfaces[2] = fSide180 ;
   surfaces[3] = fSide270 ;
   surfaces[4] = fLowerEndcap;
   surfaces[5] = fUpperEndcap;
 
   G4int besti = -1;
   G4ThreeVector xx;
   G4ThreeVector bestxx;
   for (auto 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();
      }
   }
 
   return distance;
}
 
 
//=====================================================================
//* DistanceToOut (p) -------------------------------------------------
 
G4double G4VTwistedFaceted::DistanceToOut( const G4ThreeVector& p ) const
{
   // DistanceToOut(p):
   // Calculate distance to surface of shape from `inside', 
   // allowing for tolerance
   
   //
   // Calculate DistanceToOut(p)
   //
   
   EInside currentside = Inside(p);
   G4double     retval = kInfinity;   
 
   switch (currentside)
   {
      case (kOutside) :
      {
#ifdef G4SPECSDEBUG
        G4int oldprc = G4cout.precision(16) ;
        G4cout << G4endl ;
        DumpInfo();
        G4cout << "Position:"  << G4endl << G4endl ;
        G4cout << "p.x() = "   << p.x()/mm << " mm" << G4endl ;
        G4cout << "p.y() = "   << p.y()/mm << " mm" << G4endl ;
        G4cout << "p.z() = "   << p.z()/mm << " mm" << G4endl << G4endl ;
        G4cout.precision(oldprc) ;
        G4Exception("G4VTwistedFaceted::DistanceToOut(p)", "GeomSolids1002",
                    JustWarning, "Point p is outside !?" );
#endif
        break;
      }
      case (kSurface) :
      {
        retval = 0;
        break;
      }
      
      case (kInside) :
      {
        // Initialize
        //
        G4double distance = kInfinity;
   
        // find intersections and choose nearest one
        //
        G4VTwistSurface* surfaces[6];
 
        surfaces[0] = fSide0;
        surfaces[1] = fSide90 ;
        surfaces[2] = fSide180 ;
        surfaces[3] = fSide270 ;
        surfaces[4] = fLowerEndcap;
        surfaces[5] = fUpperEndcap;
 
        G4ThreeVector xx;
        G4ThreeVector bestxx;
        for (const auto & surface : surfaces)
        {
          G4double tmpdistance = surface->DistanceTo(p, xx);
          if (tmpdistance < distance)
          {
            distance = tmpdistance;
            bestxx = xx;
          }
        }
        retval = distance;
        break;
      }
      
      default :
      {
        G4Exception("G4VTwistedFaceted::DistanceToOut(p)", "GeomSolids0003",
                    FatalException, "Unknown point location!");
        break;
      }
   } // switch end
 
   return retval;
}
 
 
//=====================================================================
//* StreamInfo --------------------------------------------------------
 
std::ostream& G4VTwistedFaceted::StreamInfo(std::ostream& os) const
{
  //
  // Stream object contents to an output stream
  //
  G4long oldprc = os.precision(16);
  os << "-----------------------------------------------------------\n"
     << "    *** Dump for solid - " << GetName() << " ***\n"
     << "    ===================================================\n"
     << " Solid type: G4VTwistedFaceted\n"
     << " Parameters: \n"
     << "  polar angle theta = "   <<  fTheta/degree      << " deg" << G4endl
     << "  azimuthal angle phi = "  << fPhi/degree        << " deg" << G4endl  
     << "  tilt angle  alpha = "   << fAlph/degree        << " deg" << G4endl  
     << "  TWIST angle = "         << fPhiTwist/degree    << " deg" << G4endl  
     << "  Half length along y (lower endcap) = "         << fDy1/cm << " cm"
     << G4endl 
     << "  Half length along x (lower endcap, bottom) = " << fDx1/cm << " cm"
     << G4endl 
     << "  Half length along x (lower endcap, top) = "    << fDx2/cm << " cm"
     << G4endl 
     << "  Half length along y (upper endcap) = "         << fDy2/cm << " cm"
     << G4endl 
     << "  Half length along x (upper endcap, bottom) = " << fDx3/cm << " cm"
     << G4endl 
     << "  Half length along x (upper endcap, top) = "    << fDx4/cm << " cm"
     << G4endl 
     << "-----------------------------------------------------------\n";
  os.precision(oldprc);
 
  return os;
}
 
 
//=====================================================================
//* DiscribeYourselfTo ------------------------------------------------
 
void G4VTwistedFaceted::DescribeYourselfTo (G4VGraphicsScene& scene) const 
{
  scene.AddSolid (*this);
}
 
 
//=====================================================================
//* GetExtent ---------------------------------------------------------
 
G4VisExtent G4VTwistedFaceted::GetExtent() const 
{
  G4double maxRad = std::sqrt( fDx*fDx + fDy*fDy);
 
  return { -maxRad, maxRad ,
           -maxRad, maxRad ,
           -fDz, fDz };
}
 
 
//=====================================================================
//* CreateSurfaces ----------------------------------------------------
 
void G4VTwistedFaceted::CreateSurfaces() 
{
   
  // create 6 surfaces of TwistedTub.
 
  if ( fDx1 == fDx2 && fDx3 == fDx4 )    // special case : Box
  {
    fSide0   = new G4TwistBoxSide("0deg", fPhiTwist, fDz, fTheta, fPhi,
                          fDy1, fDx1, fDx1, fDy2, fDx3, fDx3, fAlph, 0.*deg);
    fSide180 = new G4TwistBoxSide("180deg", fPhiTwist, fDz, fTheta, fPhi+pi,
                          fDy1, fDx1, fDx1, fDy2, fDx3, fDx3, fAlph, 180.*deg);
  }
  else   // default general case
  {
    fSide0   = new G4TwistTrapAlphaSide("0deg"   ,fPhiTwist, fDz, fTheta,
                      fPhi, fDy1, fDx1, fDx2, fDy2, fDx3, fDx4, fAlph, 0.*deg);
    fSide180 = new G4TwistTrapAlphaSide("180deg", fPhiTwist, fDz, fTheta,
                 fPhi+pi, fDy1, fDx2, fDx1, fDy2, fDx4, fDx3, fAlph, 180.*deg);
  }
 
  // create parallel sides
  //
  fSide90 = new G4TwistTrapParallelSide("90deg",  fPhiTwist, fDz, fTheta,
                      fPhi, fDy1, fDx1, fDx2, fDy2, fDx3, fDx4, fAlph, 0.*deg);
  fSide270 = new G4TwistTrapParallelSide("270deg", fPhiTwist, fDz, fTheta,
                 fPhi+pi, fDy1, fDx2, fDx1, fDy2, fDx4, fDx3, fAlph, 180.*deg);
 
  // create endcaps
  //
  fUpperEndcap = new G4TwistTrapFlatSide("UpperCap",fPhiTwist, fDx3, fDx4, fDy2,
                                    fDz, fAlph, fPhi, fTheta,  1 );
  fLowerEndcap = new G4TwistTrapFlatSide("LowerCap",fPhiTwist, fDx1, fDx2, fDy1,
                                    fDz, fAlph, fPhi, fTheta, -1 );
 
  // Set neighbour surfaces
  
  fSide0->SetNeighbours(  fSide270 , fLowerEndcap , fSide90  , fUpperEndcap );
  fSide90->SetNeighbours( fSide0   , fLowerEndcap , fSide180 , fUpperEndcap );
  fSide180->SetNeighbours(fSide90  , fLowerEndcap , fSide270 , fUpperEndcap );
  fSide270->SetNeighbours(fSide180 , fLowerEndcap , fSide0   , fUpperEndcap );
  fUpperEndcap->SetNeighbours( fSide180, fSide270 , fSide0 , fSide90  );
  fLowerEndcap->SetNeighbours( fSide180, fSide270 , fSide0 , fSide90  );
 
}
 
//=====================================================================
//* GetLateralFaceArea ------------------------------------------------
 
G4double
G4VTwistedFaceted::GetLateralFaceArea(const G4TwoVector& p1,
                                      const G4TwoVector& p2,
                                      const G4TwoVector& p3,
                                      const G4TwoVector& p4) const
{
  constexpr G4int NSTEP = 100;
  constexpr G4double dt = 1./NSTEP;
 
  G4double h = 2.*fDz;
  G4double hh = h*h;
  G4double hTanTheta = h*std::tan(fTheta);
  G4double x1 = p1.x();
  G4double y1 = p1.y();
  G4double x21 = p2.x() - p1.x();
  G4double y21 = p2.y() - p1.y();
  G4double x31 = p3.x() - p1.x();
  G4double y31 = p3.y() - p1.y();
  G4double x42 = p4.x() - p2.x();
  G4double y42 = p4.y() - p2.y();
  G4double x43 = p4.x() - p3.x();
  G4double y43 = p4.y() - p3.y();
 
  // check if face is plane (just in case)
  G4double lmax = std::max(std::max(std::abs(x21),std::abs(y21)),
                           std::max(std::abs(x43),std::abs(y43)));
  G4double eps = lmax*kCarTolerance;
  if (std::abs(fPhiTwist) < kCarTolerance &&
      std::abs(x21*y43 - y21*x43) < eps)
  {
    G4double x0 = hTanTheta*std::cos(fPhi);
    G4double y0 = hTanTheta*std::sin(fPhi);
    G4ThreeVector A(p4.x() - p1.x() + x0, p4.y() - p1.y() + y0, h);
    G4ThreeVector B(p3.x() - p2.x() + x0, p3.y() - p2.y() + y0, h);
    return (A.cross(B)).mag()*0.5;
  }
 
  // twisted face
  G4double area = 0.;
  for (G4int i = 0; i < NSTEP; ++i)
  {
    G4double t = (i + 0.5)*dt;
    G4double I = x21 + (x42 - x31)*t;
    G4double J = y21 + (y42 - y31)*t;
    G4double II = I*I;
    G4double JJ = J*J;
    G4double IIJJ = hh*(I*I + J*J);
 
    G4double ang = fPhi + fPhiTwist*(0.5 - t);
    G4double A = fPhiTwist*(II + JJ) + x21*y43 - x43*y21;
    G4double B = fPhiTwist*(I*(x1 + x31*t) + J*(y1 + y31*t)) +
      hTanTheta*(I*std::sin(ang) - J*std::cos(ang)) +
      (I*y31 - J*x31);
 
    G4double invAA = 1./(A*A);
    G4double sqrtAA = 2.*std::abs(A);
    G4double invSqrtAA = 1./sqrtAA;
 
    G4double aa = A*A;
    G4double bb = 2.*A*B;
    G4double cc = IIJJ + B*B;
 
    G4double R1 = std::sqrt(aa + bb + cc);
    G4double R0 = std::sqrt(cc);
    G4double log1 = std::log(std::abs(sqrtAA*R1 + 2.*aa + bb));
    G4double log0 = std::log(std::abs(sqrtAA*R0 + bb));
 
    area += 0.5*R1 + 0.25*bb*invAA*(R1 - R0) + IIJJ*invSqrtAA*(log1 - log0);
  }
  return area*dt;
}
 
//=====================================================================
//* GetCubicVolume ----------------------------------------------------
 
G4double G4VTwistedFaceted::GetCubicVolume()
{
  if(fCubicVolume == 0)
  {
    G4AutoLock l(&vtwMutex);
    fCubicVolume = ((fDx1 + fDx2 + fDx3 + fDx4)*(fDy1 + fDy2) +
                    (fDx4 + fDx3 - fDx2 - fDx1)*(fDy2 - fDy1)/3)*fDz;
    l.unlock();
  }
  return fCubicVolume;
}
 
//=====================================================================
//* GetSurfaceArea ----------------------------------------------------
 
G4double G4VTwistedFaceted::GetSurfaceArea()
{
  if (fSurfaceArea == 0)
  {
    G4AutoLock l(&vtwMutex);
    G4TwoVector vv[8];
    vv[0] = G4TwoVector(-fDx1 - fDy1*fTAlph,-fDy1);
    vv[1] = G4TwoVector( fDx1 - fDy1*fTAlph,-fDy1);
    vv[2] = G4TwoVector(-fDx2 + fDy1*fTAlph, fDy1);
    vv[3] = G4TwoVector( fDx2 + fDy1*fTAlph, fDy1);
    vv[4] = G4TwoVector(-fDx3 - fDy2*fTAlph,-fDy2);
    vv[5] = G4TwoVector( fDx3 - fDy2*fTAlph,-fDy2);
    vv[6] = G4TwoVector(-fDx4 + fDy2*fTAlph, fDy2);
    vv[7] = G4TwoVector( fDx4 + fDy2*fTAlph, fDy2);
    fSurfaceArea = 2.*(fDy1*(fDx1 + fDx2) + fDy2*(fDx3 + fDx4)) +
      GetLateralFaceArea(vv[0], vv[1], vv[4], vv[5]) +
      GetLateralFaceArea(vv[1], vv[3], vv[5], vv[7]) +
      GetLateralFaceArea(vv[3], vv[2], vv[7], vv[6]) +
      GetLateralFaceArea(vv[2], vv[0], vv[6], vv[4]);
    l.unlock();
  }
  return fSurfaceArea;
}
 
//=====================================================================
//* GetEntityType -----------------------------------------------------
 
G4GeometryType G4VTwistedFaceted::GetEntityType() const
{
  return {"G4VTwistedFaceted"};
}
 
 
//=====================================================================
//* GetPolyhedron -----------------------------------------------------
 
G4Polyhedron* G4VTwistedFaceted::GetPolyhedron() const
{
  if (fpPolyhedron == nullptr ||
      fRebuildPolyhedron ||
      fpPolyhedron->GetNumberOfRotationStepsAtTimeOfCreation() !=
      fpPolyhedron->GetNumberOfRotationSteps())
    {
      G4AutoLock l(&polyhedronMutex);
      delete fpPolyhedron;
      fpPolyhedron = CreatePolyhedron();
      fRebuildPolyhedron = false;
      l.unlock();
    }
 
  return fpPolyhedron;
}
 
 
//=====================================================================
//* GetPointOnSurface -------------------------------------------------
 
G4ThreeVector G4VTwistedFaceted::GetPointOnSurface() const
{
 
  G4double phi = fPhiTwist*(G4QuickRand() - 0.5);
  G4double u , umin, umax ;  //  variable for twisted surfaces
  G4double y  ;              //  variable for flat surface (top and bottom)
 
  // Compute the areas. Attention: Only correct for trapezoids
  // where the twisting is done along the z-axis. In the general case
  // the computed surface area is more difficult. However this simplification
  // does not affect the tracking through the solid. 
 
  G4double a1 = fSide0->GetSurfaceArea();
  G4double a2 = fSide90->GetSurfaceArea();
  G4double a3 = fSide180->GetSurfaceArea() ;
  G4double a4 = fSide270->GetSurfaceArea() ;
  G4double a5 = fLowerEndcap->GetSurfaceArea() ;
  G4double a6 = fUpperEndcap->GetSurfaceArea() ;
 
#ifdef G4TWISTDEBUG
  G4cout << "Surface 0   deg = " << a1 << G4endl ;
  G4cout << "Surface 90  deg = " << a2 << G4endl ;
  G4cout << "Surface 180 deg = " << a3 << G4endl ;
  G4cout << "Surface 270 deg = " << a4 << G4endl ;
  G4cout << "Surface Lower   = " << a5 << G4endl ;
  G4cout << "Surface Upper   = " << a6 << G4endl ;
#endif 
 
  G4double chose = (a1 + a2 + a3 + a4 + a5 + a6)*G4QuickRand() ;
 
  if(chose < a1)
  {
    umin = fSide0->GetBoundaryMin(phi) ;
    umax = fSide0->GetBoundaryMax(phi) ;
    u = umin + (umax - umin)*G4QuickRand();
    return  fSide0->SurfacePoint(phi, u, true) ;   // point on 0 deg surface
  }
  if( (chose >= a1) && (chose < a1 + a2 ) )
  {
    umin = fSide90->GetBoundaryMin(phi) ;
    umax = fSide90->GetBoundaryMax(phi) ;
    u = umin + (umax - umin)*G4QuickRand();
    return fSide90->SurfacePoint(phi, u, true);   // point on 90 deg surface
  }
  if( (chose >= a1 + a2 ) && (chose < a1 + a2 + a3 ) )
  {
    umin = fSide180->GetBoundaryMin(phi) ;
    umax = fSide180->GetBoundaryMax(phi) ;
    u = umin + (umax - umin)*G4QuickRand();
    return fSide180->SurfacePoint(phi, u, true); // point on 180 deg surface
  }
  if( (chose >= a1 + a2 + a3  ) && (chose < a1 + a2 + a3 + a4  ) )
  {
    umin = fSide270->GetBoundaryMin(phi) ;
    umax = fSide270->GetBoundaryMax(phi) ;
    u = umin + (umax - umin)*G4QuickRand();
    return fSide270->SurfacePoint(phi, u, true); // point on 270 deg surface
  }
  if( (chose >= a1 + a2 + a3 + a4  ) && (chose < a1 + a2 + a3 + a4 + a5 ) )
  {
    y = fDy1*(2.*G4QuickRand() - 1.);
    umin = fLowerEndcap->GetBoundaryMin(y) ;
    umax = fLowerEndcap->GetBoundaryMax(y) ;
    u = umin + (umax - umin)*G4QuickRand();
    return fLowerEndcap->SurfacePoint(u,y,true); // point on lower endcap
  }
  y = fDy2*(2.*G4QuickRand() - 1.);
  umin = fUpperEndcap->GetBoundaryMin(y) ;
  umax = fUpperEndcap->GetBoundaryMax(y) ;
  u = umin + (umax - umin)*G4QuickRand();
  return fUpperEndcap->SurfacePoint(u,y,true); // point on upper endcap
}
 
 
//=====================================================================
//* CreatePolyhedron --------------------------------------------------
 
G4Polyhedron* G4VTwistedFaceted::CreatePolyhedron () const 
{
  // number of meshes
  const G4int k =
  G4int(G4Polyhedron::GetNumberOfRotationSteps() *
        std::abs(fPhiTwist) / twopi) + 2;
  const G4int n = k;
 
  const G4int nnodes = 4*(k-1)*(n-2) + 2*k*k ;
  const G4int nfaces = 4*(k-1)*(n-1) + 2*(k-1)*(k-1) ;
 
  auto  ph = new G4Polyhedron;
  typedef G4double G4double3[3];
  typedef G4int G4int4[4];
  auto xyz = new G4double3[nnodes];  // number of nodes 
  auto faces = new G4int4[nfaces] ;  // number of faces
 
  fLowerEndcap->GetFacets(k,k,xyz,faces,0) ;
  fUpperEndcap->GetFacets(k,k,xyz,faces,1) ;
  fSide270->GetFacets(k,n,xyz,faces,2) ;
  fSide0->GetFacets(k,n,xyz,faces,3) ;
  fSide90->GetFacets(k,n,xyz,faces,4) ;
  fSide180->GetFacets(k,n,xyz,faces,5) ;
 
  ph->createPolyhedron(nnodes,nfaces,xyz,faces);
 
  return ph;
}