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//
// $Id: G4Trap.hh,v 1.17 2006/10/19 15:33:37 gcosmo Exp $
// GEANT4 tag $Name: geant4-09-03 $
//
// 
// --------------------------------------------------------------------
// GEANT 4 class header file
//
// G4Trap
//
// Class description:
//
//   A G4Trap is a general trapezoid: The faces perpendicular to the
//   z planes are trapezia, and their centres are not necessarily on
//   a line parallel to the z axis.
//
//   Note that of the 11 parameters described below, only 9 are really
//   independent - a check for planarity is made in the calculation of the
//   equation for each plane. If the planes are not parallel, a call to
//   G4Exception is made.
//
//      pDz     Half-length along the z-axis
//      pTheta  Polar angle of the line joining the centres of the faces
//              at -/+pDz
//      pPhi    Azimuthal angle of the line joing the centre of the face at
//              -pDz to the centre of the face at +pDz
//      pDy1    Half-length along y of the face at -pDz
//      pDx1    Half-length along x of the side at y=-pDy1 of the face at -pDz
//      pDx2    Half-length along x of the side at y=+pDy1 of the face at -pDz
//      pAlp1   Angle with respect to the y axis from the centre of the side
//              at y=-pDy1 to the centre at y=+pDy1 of the face at -pDz
//
//      pDy2    Half-length along y of the face at +pDz
//      pDx3    Half-length along x of the side at y=-pDy2 of the face at +pDz
//      pDx4    Half-length along x of the side at y=+pDy2 of the face at +pDz
//      pAlp2   Angle with respect to the y axis from the centre of the side
//              at y=-pDy2 to the centre at y=+pDy2 of the face at +pDz
//
//
//   Member Data:
//
//      fDz     Half-length along the z axis
//      fTthetaCphi = std::tan(pTheta)*std::cos(pPhi)
//      fTthetaSphi = std::tan(pTheta)*std::sin(pPhi)
//      These combinations are suitable for creation of the trapezoid corners
//
//      fDy1    Half-length along y of the face at -fDz
//      fDx1    Half-length along x of the side at y=-fDy1 of the face at -fDz
//      fDx2    Half-length along x of the side at y=+fDy1 of the face at -fDz
//      fTalpha1   Tan of Angle with respect to the y axis from the centre of
//                 the side at y=-fDy1 to the centre at y=+fDy1 of the face
//                 at -fDz
//
//      fDy2    Half-length along y of the face at +fDz
//      fDx3    Half-length along x of the side at y=-fDy2 of the face at +fDz
//      fDx4    Half-length along x of the side at y=+fDy2 of the face at +fDz
//      fTalpha2   Tan of Angle with respect to the y axis from the centre of
//                 the side at y=-fDy2 to the centre at y=+fDy2 of the face
//                 at +fDz
//
//      TrapSidePlane fPlanes[4]   Plane equations of the faces not at +/-fDz
//                                 NOTE: order is important !!!

// History:
//
// 23.3.94 P.Kent: Old C++ code converted to tolerant geometry
// 9.9.96  V.Grichine: Final modifications before to commit 
// 1.11.96 V.Grichine: Costructors for Right Angular Wedge from STEP, G4Trd/Para
// 8.12.97 J.Allison: Added "nominal" contructor and method SetAllParameters.
// --------------------------------------------------------------------

#ifndef G4Trap_HH
#define G4Trap_HH

#include "G4CSGSolid.hh"

struct TrapSidePlane
{
    G4double a,b,c,d;    // Normal unit vector (a,b,c)  and offset (d)
        // => Ax+By+Cz+D=0  
};

class G4Trap : public G4CSGSolid
{

  public:  // with description

    G4Trap( const G4String& pName,
                  G4double pDz,
                  G4double pTheta, G4double pPhi,
                  G4double pDy1, G4double pDx1, G4double pDx2,
                  G4double pAlp1,
                  G4double pDy2, G4double pDx3, G4double pDx4,
                  G4double pAlp2 );
      //
      // The most general constructor for G4Trap which prepares plane
      // equations and corner coordinates from parameters

    G4Trap( const G4String& pName,
            const G4ThreeVector pt[8] ) ;
      //
      // Prepares plane equations and parameters from corner coordinates

    G4Trap( const G4String& pName,
                  G4double pZ,
                  G4double pY,
                  G4double pX, G4double pLTX );
      //
      // Constructor for Right Angular Wedge from STEP (assumes pLTX<=pX)

    G4Trap( const G4String& pName,
                  G4double pDx1,  G4double pDx2,
                  G4double pDy1,  G4double pDy2,
                  G4double pDz );
      //
      // Constructor for G4Trd       

     G4Trap(const G4String& pName,
                  G4double pDx, G4double pDy, G4double pDz,
                  G4double pAlpha, G4double pTheta, G4double pPhi );
      //
      // Constructor for G4Para

     G4Trap( const G4String& pName );
       //
       // Constructor for "nominal" G4Trap whose parameters are to be set
       // by a G4VPVParamaterisation later

     virtual ~G4Trap() ;
       //
       // Destructor

  // Accessors

    inline G4double GetZHalfLength()  const;
    inline G4double GetYHalfLength1() const;
    inline G4double GetXHalfLength1() const;
    inline G4double GetXHalfLength2() const;
    inline G4double GetTanAlpha1()    const;
    inline G4double GetYHalfLength2() const;
    inline G4double GetXHalfLength3() const;
    inline G4double GetXHalfLength4() const;
    inline G4double GetTanAlpha2()    const;
      //
      // Returns coordinates of unit vector along straight
      // line joining centers of -/+fDz planes   

    inline TrapSidePlane GetSidePlane( G4int n ) const;
    inline G4ThreeVector GetSymAxis() const;

  // Modifiers

    void SetAllParameters ( G4double pDz,
                            G4double pTheta,
                            G4double pPhi,
                            G4double pDy1,
                            G4double pDx1,
                            G4double pDx2,
                            G4double pAlp1,
                            G4double pDy2,
                            G4double pDx3,
                            G4double pDx4,
                            G4double pAlp2 );
                                
  // Methods for solid
    
    inline G4double GetCubicVolume();
    inline G4double GetSurfaceArea();

    void ComputeDimensions(       G4VPVParameterisation* p,
                            const G4int n,
                            const G4VPhysicalVolume* pRep );

    G4bool CalculateExtent( const EAxis pAxis,
                            const G4VoxelLimits& pVoxelLimit,
                            const G4AffineTransform& pTransform,
                                  G4double& pMin, G4double& pMax ) const;    
        
    EInside Inside( const G4ThreeVector& p ) const;
    
    G4ThreeVector SurfaceNormal( const G4ThreeVector& p ) const;

    G4double DistanceToIn(const G4ThreeVector& p, const G4ThreeVector& v) const;
    
    G4double DistanceToIn( const G4ThreeVector& p ) const;
    
    G4double DistanceToOut(const G4ThreeVector& p, const G4ThreeVector& v,
                           const G4bool calcNorm=false,
                                 G4bool *validNorm=0, G4ThreeVector *n=0) const;
         
    G4double DistanceToOut( const G4ThreeVector& p ) const;

    G4GeometryType GetEntityType() const;

    G4ThreeVector GetPointOnSurface() const;

    std::ostream& StreamInfo( std::ostream& os ) const;

  // Visualisation functions

    void          DescribeYourselfTo ( G4VGraphicsScene& scene  ) const;
    G4Polyhedron* CreatePolyhedron   () const;
    G4NURBS*      CreateNURBS        () const;

  public:  // without description

    G4Trap(__void__&);
      // Fake default constructor for usage restricted to direct object
      // persistency for clients requiring preallocation of memory for
      // persistifiable objects.

  protected:  // with description

    G4bool MakePlanes();
    G4bool MakePlane( const G4ThreeVector& p1,
                      const G4ThreeVector& p2,
                      const G4ThreeVector& p3, 
                      const G4ThreeVector& p4,
                            TrapSidePlane& plane ) ;

    G4ThreeVectorList*
    CreateRotatedVertices( const G4AffineTransform& pTransform ) const;
      //
      // Creates the List of transformed vertices in the format required
      // for G4CSGSolid:: ClipCrossSection and ClipBetweenSections

  private:

    G4ThreeVector ApproxSurfaceNormal( const G4ThreeVector& p ) const;
      // Algorithm for SurfaceNormal() following the original
      // specification for points not on the surface

    inline G4double GetFaceArea(const G4ThreeVector& p1,
                                const G4ThreeVector& p2, 
                                const G4ThreeVector& p3,
                                const G4ThreeVector& p4);
      //
      // Provided four corners of plane in clockwise fashion,
      // it returns the area of finite face

    G4ThreeVector GetPointOnPlane(G4ThreeVector p0, G4ThreeVector p1, 
                                  G4ThreeVector p2, G4ThreeVector p3, 
                                  G4double& area) const;
      //
      // Returns a random point on the surface of one of the faces

  private:

    G4double fDz,fTthetaCphi,fTthetaSphi;
    G4double fDy1,fDx1,fDx2,fTalpha1;
    G4double fDy2,fDx3,fDx4,fTalpha2;
    TrapSidePlane fPlanes[4];

};

#include "G4Trap.icc"

#endif
