//----------------------------------------------------------------------------
//  EgalTech 2014-2014
//----------------------------------------------------------------------------
// File : CalcDerivate.h   Data : 05.08.14       Versione : 1.5h1
// Contenuto : Funzioni per calcolo derivate secondo Bessel e Akima.
//
//
//
// Modifiche : 05.08.14 DS Creazione modulo.
//
//
//----------------------------------------------------------------------------

#pragma once

#include "/EgtDev/Include/EGkPoint3d.h"


//----------------------------------------------------------------------------
inline bool
CalcBesselStartDer( double dU0, const Point3d& ptP0, double dU1, const Point3d& ptP1,
                    double dU2, const Point3d& ptP2, Vector3d& vtDer)
{
  // verifico che i parametri siano in ordine ascendente
   if ( dU0 > dU1 - EPS_PARAM  ||  dU1 > dU2 - EPS_PARAM)
      return false ;
  // calcolo la derivata
   double dD0 = dU1 - dU0 ;
   double dD1 = dU2 - dU1 ;
   double dD01 = dU2 - dU0 ;
   vtDer = ( 2 * dD0 + dD1) / ( dD0 * dD01) * ( ptP1 - ptP0) - dD0 / ( dD01 * dD1) * ( ptP2 - ptP1) ;   
   return ( ! vtDer.IsZero()) ;
}

//----------------------------------------------------------------------------
inline bool
CalcBesselMidDer( double dU0, const Point3d& ptP0, double dU1, const Point3d& ptP1,
                  double dU2, const Point3d& ptP2, Vector3d& vtDer)
{
  // verifico che i parametri siano in ordine ascendente
   if ( dU0 > dU1 - EPS_PARAM  ||  dU1 > dU2 - EPS_PARAM)
      return false ;
  // calcolo la derivata
   double dD0 = dU1 - dU0 ;
   double dD1 = dU2 - dU1 ;
   double dD01 = dU2 - dU0 ;
   vtDer = dD1 / ( dD0 * dD01) * ( ptP1 - ptP0) + dD0 / ( dD01 * dD1) * ( ptP2 - ptP1) ;   
   return ( ! vtDer.IsZero()) ;
}

//----------------------------------------------------------------------------
inline bool
CalcBesselEndDer( double dU0, const Point3d& ptP0, double dU1, const Point3d& ptP1,
                  double dU2, const Point3d& ptP2, Vector3d& vtDer)
{
  // verifico che i parametri siano in ordine ascendente
   if ( dU0 > dU1 - EPS_PARAM  ||  dU1 > dU2 - EPS_PARAM)
      return false ;
  // calcolo la derivata
   double dD0 = dU1 - dU0 ;
   double dD1 = dU2 - dU1 ;
   double dD01 = dU2 - dU0 ;
   vtDer = - dD1 / ( dD0 * dD01) * ( ptP1 - ptP0) + ( dD0 + 2 * dD1) / ( dD01 * dD1) * ( ptP2 - ptP1) ;   
   return ( ! vtDer.IsZero()) ;
}

//----------------------------------------------------------------------------
inline bool
CalcCircleStartDer( double dU0, const Point3d& ptP0, double dU1, const Point3d& ptP1,
                    double dU2, const Point3d& ptP2, Vector3d& vtDer)
{
  // verifico che i parametri siano in ordine ascendente
   if ( dU0 > dU1 - EPS_PARAM  ||  dU1 > dU2 - EPS_PARAM)
      return false ;
  // vettori dal primo punto agli altri due
   Vector3d vtA = ptP1 - ptP0 ;
   Vector3d vtB = ptP2 - ptP0 ;
  // calcolo del versore normale
   Vector3d vtN = vtA ^ vtB ;
   double dNSqLen = vtN.SqLen() ;
   // se i punti sono allineati calcolo con Bessel
   if ( ! vtN.Normalize( EPS_ZERO))
      return CalcBesselStartDer( dU0, ptP0, dU1, ptP1, dU2, ptP2, vtDer) ;
  // calcolo del centro
   Point3d ptCen = ptP0 + ( vtB.SqLen() * ( vtA.SqLen() - vtA * vtB) * vtA +  
                          vtA.SqLen() * ( vtB.SqLen() - vtA * vtB) * vtB) / ( 2 * dNSqLen) ;
  // calcolo la derivata
   vtDer = ptP0 - ptCen ;
   vtDer.Rotate( vtN, 0, 1) ;
   if ( ( vtDer * vtA) < 0)
      vtDer.Invert() ;
   // ne aggiusto il modulo
   if ( ! vtDer.Normalize())
      return false ;
   vtDer *= Dist( ptP0, ptP1) / ( dU1 - dU0) ;
   return true ;
}

//----------------------------------------------------------------------------
inline bool
CalcCircleEndDer( double dU0, const Point3d& ptP0, double dU1, const Point3d& ptP1,
                  double dU2, const Point3d& ptP2, Vector3d& vtDer)
{
  // verifico che i parametri siano in ordine ascendente
   if ( dU0 > dU1 - EPS_PARAM  ||  dU1 > dU2 - EPS_PARAM)
      return false ;
  // vettori dal primo punto agli altri due
   Vector3d vtA = ptP1 - ptP0 ;
   Vector3d vtB = ptP2 - ptP0 ;
  // calcolo del versore normale
   Vector3d vtN = vtA ^ vtB ;
   double dNSqLen = vtN.SqLen() ;
   // se i punti sono allineati calcolo con Bessel
   if ( ! vtN.Normalize( EPS_ZERO))
      return CalcBesselEndDer( dU0, ptP0, dU1, ptP1, dU2, ptP2, vtDer) ;
  // calcolo del centro
   Point3d ptCen = ptP0 + ( vtB.SqLen() * ( vtA.SqLen() - vtA * vtB) * vtA +  
                          vtA.SqLen() * ( vtB.SqLen() - vtA * vtB) * vtB) / ( 2 * dNSqLen) ;
  // calcolo la derivata
   vtDer = ptP2 - ptCen ;
   vtDer.Rotate( vtN, 0, 1) ;
   if ( ( vtDer * ( ptP2 - ptP1)) < 0)
      vtDer.Invert() ;
   // ne aggiusto il modulo
   if ( ! vtDer.Normalize())
      return false ;
   vtDer *= Dist( ptP1, ptP2) / ( dU2 - dU1) ;
   return true ;
}

//----------------------------------------------------------------------------
inline bool
CalcCircleMidDer( double dU0, const Point3d& ptP0, double dU1, const Point3d& ptP1,
                  double dU2, const Point3d& ptP2, Vector3d& vtDer)
{
  // la derivata Bessel coincide con la derivata circolare sul punto in mezzo
   return CalcBesselMidDer( dU0, ptP0, dU1, ptP1, dU2, ptP2, vtDer) ;
}

//----------------------------------------------------------------------------
inline bool
CalcAkimaMidDer( double dU0, const Point3d& ptP0, double dU1, const Point3d& ptP1,
                 double dU2, const Point3d& ptP2, double dU3, const Point3d& ptP3,
                 double dU4, const Point3d& ptP4, bool bDetectCorner,
                 Vector3d& vtPrevDer, Vector3d& vtNextDer)
{
  // verifico che i parametri siano in ordine crescente
   if ( dU0 > dU1 - EPS_PARAM  ||  dU1 > dU2 - EPS_PARAM  ||
        dU2 > dU3 - EPS_PARAM  ||  dU3 > dU4 - EPS_PARAM)
      return false ;
  // calcolo la derivata
   Vector3d vtV0 = ( ptP1 - ptP0) / ( dU1 - dU0) ;
   Vector3d vtV1 = ( ptP2 - ptP1) / ( dU2 - dU1) ;
   Vector3d vtV2 = ( ptP3 - ptP2) / ( dU3 - dU2) ;
   Vector3d vtV3 = ( ptP4 - ptP3) / ( dU4 - dU3) ;
   Vector3d vtPV1 = vtV0 ^ vtV1 ;
   Vector3d vtPV3 = vtV2 ^ vtV3 ;
   double dPV1 = vtPV1.Len()  ;
   double dPV3 = vtPV3.Len() ;
   if ( ( dPV1 + dPV3) > EPS_SMALL  &&  ( vtV1 * vtV2) > 0.5) {
      if ( ! bDetectCorner  ||  ( ( vtV0 * vtV1) > 0  &&  ( vtV2 * vtV3) > 0)) {
         double dA = dPV1 / ( dPV1 + dPV3) ;
         vtPrevDer = ( 1 - dA) * vtV1 + dA * vtV2 ;
      }
      else {
         CalcCircleMidDer( dU1, ptP1, dU2, ptP2, dU3, ptP3, vtPrevDer) ;
      }
      vtNextDer = vtPrevDer ;
   }
   else {
      if ( bDetectCorner) {
         CalcCircleEndDer( dU0, ptP0, dU1, ptP1, dU2, ptP2, vtPrevDer) ;
         CalcCircleStartDer( dU2, ptP2, dU3, ptP3, dU4, ptP4, vtNextDer) ;
      }
      else {
         vtPrevDer = 0.5 * ( vtV1 + vtV2) ;
         vtNextDer = vtPrevDer ;
      }
   }
   return ( ! vtPrevDer.IsZero()  &&  ! vtNextDer.IsZero()) ;
}