calc_shadow_zones.cpp

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/* ==============================================================================================================================
   This file is part of CoastalME, the Coastal Modelling Environment.
 
   CoastalME is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.
 
   This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
==============================================================================================================================*/
#include <assert.h>
#include <cmath>
 
#include <iostream>
using std::endl;
 
#include <stack>
using std::stack;
 
#include <deque>
using std::deque;
 
#include <numeric>
using std::accumulate;
 
#include "cme.h"
#include "coast.h"
#include "simulation.h"
#include "raster_grid.h"
#include "2d_point.h"
#include "2di_point.h"
#include "line.h"
#include "i_line.h"
 
//===============================================================================================================================
//===============================================================================================================================
bool CSimulation::bOnOrOffShoreAndUpOrDownCoast(double const dCoastAngle, double const dWaveAngle, int const nSeaHand, bool& bDownCoast)
{
   bool bOnShore;
   double const dWaveToCoastAngle = fmod((dWaveAngle - dCoastAngle + 360), 360);
 
   bDownCoast = ((dWaveToCoastAngle > 270) || (dWaveToCoastAngle < 90)) ? true : false;
 
   if (nSeaHand == RIGHT_HANDED)
   {
      // The sea is on the RHS when travelling down-coast (i.e. along the coast in the direction of increasing coastline point numbers)
      bOnShore = dWaveToCoastAngle > 180 ? true : false;
   }
   else
   {
      // The sea is on the LHS when travelling down-coast (i.e. along the coast in the direction of increasing coastline point numbers)
      bOnShore = dWaveToCoastAngle > 180 ? false : true;
   }
 
   return bOnShore;
}
 
//===============================================================================================================================
//===============================================================================================================================
CGeom2DIPoint CSimulation::PtiFollowWaveAngle(CGeom2DIPoint const* pPtiLast, double const dWaveAngleIn, double& dCorrection)
{
   int const nXLast = pPtiLast->nGetX();
   int const nYLast = pPtiLast->nGetY();
   int nXNext = nXLast;
   int nYNext = nYLast;
 
   double const dWaveAngle = dWaveAngleIn - dCorrection;
 
   if (dWaveAngle < 22.5)
   {
      nYNext--;
      dCorrection = 22.5 - dWaveAngle;
   }
   else if (dWaveAngle < 67.5)
   {
      nYNext--;
      nXNext++;
      dCorrection = 67.5 - dWaveAngle;
   }
   else if (dWaveAngle < 112.5)
   {
      nXNext++;
      dCorrection = 112.5 - dWaveAngle;
   }
   else if (dWaveAngle < 157.5)
   {
      nXNext++;
      nYNext++;
      dCorrection = 157.5 - dWaveAngle;
   }
   else if (dWaveAngle < 202.5)
   {
      nYNext++;
      dCorrection = 202.5 - dWaveAngle;
   }
   else if (dWaveAngle < 247.5)
   {
      nXNext--;
      nYNext++;
      dCorrection = 247.5 - dWaveAngle;
   }
   else if (dWaveAngle < 292.5)
   {
      nXNext--;
      dCorrection = 292.5 - dWaveAngle;
   }
   else if (dWaveAngle < 337.5)
   {
      nXNext--;
      nYNext--;
      dCorrection = 337.5 - dWaveAngle;
   }
   else
   {
      nYNext--;
      dCorrection = 22.5 - dWaveAngle;
   }
 
   dCorrection = dKeepWithin360(dCorrection);
 
   return CGeom2DIPoint(nXNext, nYNext);
}
 
//===============================================================================================================================
//===============================================================================================================================
int CSimulation::nDoAllShadowZones(void)
{
   if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
      LogStream << endl << m_ulIter << ": Finding shadow zones" << endl;
 
   // Do this once for each coastline
   for (int nCoast = 0; nCoast < static_cast<int>(m_VCoast.size()); nCoast++)
   {
      // =========================================================================================================================
      // The first stage: find coastline start points for possible shadow zone boundaries by sweeping the coastline: first down-coast then up-coast
      int const nSeaHand = m_VCoast[nCoast].nGetSeaHandedness();
      int const nCoastSize = m_VCoast[nCoast].nGetCoastlineSize();
      vector<int> VnPossibleShadowBoundaryCoastPoint;
 
      for (bool bDownCoast : {true, false})
      {
         if (bDownCoast)
         {
            bool bLastDownCoastAndOnshore = false;
 
            // Work along coast in down-coast direction
            for (int nCoastPoint = 0; nCoastPoint < nCoastSize; nCoastPoint++)
            {
               // Get the coast's smoothed curvature at this point
               double const dCurvature = m_VCoast[nCoast].dGetSmoothCurvature(nCoastPoint);
               if (dCurvature <= 0)
               {
                  // OK, the coast is convex (-ve) or straight (0) here, now get the flux orientation (a tangent to the coastline)
                  double const dFluxOrientation = m_VCoast[nCoast].dGetFluxOrientation(nCoastPoint);
 
                  // If this coast point is in the active zone, use the breaking wave orientation, otherwise use the deep water wave orientation
                  double dWaveAngle;
 
                  if (bFPIsEqual(m_VCoast[nCoast].dGetDepthOfBreaking(nCoastPoint), DBL_NODATA, TOLERANCE))
                     // Not in active zone
                     dWaveAngle = m_VCoast[nCoast].dGetCoastDeepWaterWaveAngle(nCoastPoint);
                  else
                     // In active zone
                     dWaveAngle = m_VCoast[nCoast].dGetBreakingWaveAngle(nCoastPoint);
 
                  // At this point on the coast, are waves on- or off-shore, and up- or down-coast?
                  bDownCoast = false;
                  bool const bOnShore = bOnOrOffShoreAndUpOrDownCoast(dFluxOrientation, dWaveAngle, nSeaHand, bDownCoast);
 
                  // if (m_nLogFileDetail >= LOG_FILE_ALL)
                  // {
                  //    CGeom2DPoint PtTmp1 = *m_VCoast[nCoast].pPtGetCoastlinePointExtCRS(nCoastPoint);
                  //    LogStream << m_ulIter << ": going down-coast along coast " << nCoast << " coast point " << nCoastPoint << " = {" << PtTmp1.dGetX() << ", " << PtTmp1.dGetY() << "} has " << (bDownCoast ? "down-coast " : "up-coast ") << (bOnShore ? "on-shore" : "off-shore") << " waves, dWaveAngle = " << dWaveAngle << " dFluxOrientation = " << dFluxOrientation << endl;
                  // }
 
                  if (bDownCoast && (! bOnShore))
                  {
                     // Waves are down-coast and off-shore
                     // if (m_nLogFileDetail >= LOG_FILE_ALL)
                     // {
                     //    CGeom2DPoint PtTmp1 = *m_VCoast[nCoast].pPtGetCoastlinePointExtCRS(nCoastPoint);
                     //    LogStream << m_ulIter << ": going down-coast along coast " << nCoast << " at coast point " << nCoastPoint << " = {" << PtTmp1.dGetX() << ", " << PtTmp1.dGetY() << "}, waves have off-shore and down-coast component" << endl;
                     // }
 
                     // If the previous coast point had waves which were down-coast and on-shore, then this could be the boundary of a shadow zone
                     if (bLastDownCoastAndOnshore)
                     {
                        VnPossibleShadowBoundaryCoastPoint.push_back(nCoastPoint);
                        bLastDownCoastAndOnshore = false;
 
                        // if (m_nLogFileDetail >= LOG_FILE_ALL)
                        // {
                        //    CGeom2DPoint PtTmp = *m_VCoast[nCoast].pPtGetCoastlinePointExtCRS(nCoastPoint);
                        //    LogStream << m_ulIter << ": coast " << nCoast << " coast point " << nCoastPoint << " = {" << PtTmp.dGetX() << ", " << PtTmp.dGetY() << "} is possible shadow boundary start" << endl;
                        // }
                     }
                  }
                  else if (bDownCoast && bOnShore)
                  {
                     bLastDownCoastAndOnshore = true;
                  }
                  else
                  {
                     bLastDownCoastAndOnshore = false;
                  }
               }
            }
         }
         else
         {
            // Moving along coast in up-coast direction
            bool bLastUpCoastAndOnshore = false;
 
            // Work along coast in up-coast direction
            for (int nCoastPoint = nCoastSize - 1; nCoastPoint >= 0; nCoastPoint--)
            {
               // Get the coast's smoothed curvature at this point
               double const dCurvature = m_VCoast[nCoast].dGetSmoothCurvature(nCoastPoint);
               if (dCurvature <= 0)
               {
                  // OK, the coast is convex (-ve) or straight (0) here, now get the flux orientation (a tangent to the coastline)
                  double const dFluxOrientation = m_VCoast[nCoast].dGetFluxOrientation(nCoastPoint);
 
                  // If this coast point is in the active zone, use the breaking wave orientation, otherwise use the deep water wave orientation
                  double dWaveAngle;
 
                  if (bFPIsEqual(m_VCoast[nCoast].dGetDepthOfBreaking(nCoastPoint), DBL_NODATA, TOLERANCE))
                     // Not in active zone
                     dWaveAngle = m_VCoast[nCoast].dGetCoastDeepWaterWaveAngle(nCoastPoint);
                  else
                     // In active zone
                     dWaveAngle = m_VCoast[nCoast].dGetBreakingWaveAngle(nCoastPoint);
 
                  // At this point on the coast, are waves on- or off-shore, and up- or down-coast?
                  bDownCoast = false;
                  bool const bOnShore = bOnOrOffShoreAndUpOrDownCoast(dFluxOrientation, dWaveAngle, nSeaHand, bDownCoast);
 
                  // if (m_nLogFileDetail >= LOG_FILE_ALL)
                  // {
                  //    CGeom2DPoint PtTmp1 = *m_VCoast[nCoast].pPtGetCoastlinePointExtCRS(nCoastPoint);
                  //    LogStream << m_ulIter << ": going up-coast along coast " << nCoast << " coast point " << nCoastPoint << " = {" << PtTmp1.dGetX() << ", " << PtTmp1.dGetY() << "} has " << (bDownCoast ? "down-coast " : "up-coast ") << (bOnShore ? "on-shore" : "off-shore") << " waves, dWaveAngle = " << dWaveAngle << " dFluxOrientation = " << dFluxOrientation << endl;
                  // }
 
                  if ((! bDownCoast) && (! bOnShore))
                  {
                     // Waves are up-coast and off-shore
                     // if (m_nLogFileDetail >= LOG_FILE_ALL)
                     // {
                     //    CGeom2DPoint PtTmp1 = *m_VCoast[nCoast].pPtGetCoastlinePointExtCRS(nCoastPoint);
                     //    LogStream << m_ulIter << ": going up-coast along coast " << nCoast << " coast point " << nCoastPoint << " = {" << PtTmp1.dGetX() << ", " << PtTmp1.dGetY() << " has waves with off-shore and up-coast component" << endl;
                     // }
 
                     // If the previous coast point had waves which were up-coast and on-shore, then this could be the boundary of a shadow zone
                     if (bLastUpCoastAndOnshore)
                     {
                        VnPossibleShadowBoundaryCoastPoint.push_back(nCoastPoint);
                        bLastUpCoastAndOnshore = false;
 
                        // if (m_nLogFileDetail >= LOG_FILE_ALL)
                        // {
                        //    CGeom2DPoint PtTmp = *m_VCoast[nCoast].pPtGetCoastlinePointExtCRS(nCoastPoint);
                        //    LogStream << m_ulIter << ": going up-coast long " << nCoast << " at coast point " << nCoastPoint << " = {" << PtTmp.dGetX() << ", " << PtTmp.dGetY() << "} is possible shadow boundary start" << endl;
                        // }
                     }
                  }
                  else if ((! bDownCoast) && bOnShore)
                  {
                     bLastUpCoastAndOnshore = true;
                  }
                  else
                  {
                     bLastUpCoastAndOnshore = false;
                  }
               }
            }
         }
      }
 
      if (VnPossibleShadowBoundaryCoastPoint.size() == 0)
      {
         if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
            LogStream << m_ulIter << ": \tno shadow boundary start points found" << endl;
 
         return RTN_OK;
      }
 
      // =========================================================================================================================
      // The second stage: we have a list of possible shadow zone start points, trace each of these 'up-wave' to identify valid shadow zones
      // LogStream << VnPossibleShadowBoundaryCoastPoint.size() << " start points" << endl;
 
      vector<CGeomILine> VILShadowBoundary;
      vector<int> VnShadowBoundaryStartCoastPoint;
      vector<int> VnShadowBoundaryEndCoastPoint;
 
      for (int nStartPoint = 0; nStartPoint < static_cast<int>(VnPossibleShadowBoundaryCoastPoint.size()); nStartPoint++)
      {
         // if (m_nLogFileDetail >= LOG_FILE_ALL)
         //    LogStream << m_ulIter << ": coast " << nCoast << " processing possible shadow boundary start point " << nStartPoint << " of " << VnPossibleShadowBoundaryCoastPoint.size() << endl;
 
         bool bHitEdge = false;
         bool bHitCoast = false;
         bool bHitSea = false;
         bool bInLoop = false;
         bool bStillInland = false;
 
         // From each start point, follow the wave direction
         CGeomILine ILShadowBoundary;
 
         // If this coast point is in the active zone, start with the breaking wave orientation, otherwise use the deep water wave orientation
         double dPrevWaveAngle;
 
         if (bFPIsEqual(m_VCoast[nCoast].dGetDepthOfBreaking(nStartPoint), DBL_NODATA, TOLERANCE))
         {
            // Not in active zone
            dPrevWaveAngle = m_VCoast[nCoast].dGetCoastDeepWaterWaveAngle(nStartPoint);
         }
         else
         {
            // In active zone
            dPrevWaveAngle = m_VCoast[nCoast].dGetBreakingWaveAngle(nStartPoint);
         }
 
         CGeom2DIPoint PtiPrev = *m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(VnPossibleShadowBoundaryCoastPoint[nStartPoint]);
         ILShadowBoundary.Append(&PtiPrev);
 
         int nDist = 0;
         double dCorrection = 0;
         deque<double> DQdPrevOrientations;
 
         while ((! bHitEdge) && (! bHitCoast))
         {
            // int nShadowBoundaryCoastPoint = -1;
 
            if (nDist > 0)
            {
               int const nXPrev = PtiPrev.nGetX();
               int const nYPrev = PtiPrev.nGetY();
 
               if (! m_pRasterGrid->m_Cell[nXPrev][nYPrev].bIsInActiveZone())
               {
                  // The previous cell was outside the active zone, so use its wave orientation value
                  dPrevWaveAngle = m_pRasterGrid->m_Cell[nXPrev][nYPrev].dGetWaveAngle();
               }
               else
               {
                  // The previous cell was in the active zone
                  if (bHitSea)
                  {
                     // If this shadow boundary has already hit sea, then we must be getting near a coast: use the average-so-far wave orientation
                     double const dAvgOrientationSoFar = accumulate(DQdPrevOrientations.begin(), DQdPrevOrientations.end(), 0.0) / static_cast<double>(DQdPrevOrientations.size());
 
                     dPrevWaveAngle = dAvgOrientationSoFar;
                  }
                  else
                  {
                     // This shadow boundary has not already hit sea, just use the wave orientation from the previous cell
                     dPrevWaveAngle = m_pRasterGrid->m_Cell[nXPrev][nYPrev].dGetWaveAngle();
 
                     // LogStream << m_ulIter << ": not already hit sea, using previous cell's wave orientation for cell [" << nXPrev << "][" << nYPrev << "] = {" << dGridCentroidXToExtCRSX(nXPrev) << ", " << dGridCentroidYToExtCRSY(nYPrev) << "}" << endl;
                  }
               }
 
               if (bFPIsEqual(dPrevWaveAngle, DBL_NODATA, TOLERANCE))
               {
                  // LogStream << m_ulIter << ": dPrevWaveAngle == DBL_NODATA for cell [" << nXPrev << "][" << nYPrev << "] = {" << dGridCentroidXToExtCRSX(nXPrev) << ", " << dGridCentroidYToExtCRSY(nYPrev) << "}" << endl;
 
                  if (! m_pRasterGrid->m_Cell[nXPrev][nYPrev].bIsInContiguousSea())
                  {
                     // The previous cell was an inland cell, so use the deep water wave orientation
                     dPrevWaveAngle = m_pRasterGrid->m_Cell[nXPrev][nYPrev].dGetCellDeepWaterWaveAngle();
                  }
                  else
                  {
                     double const dAvgOrientationSoFar = accumulate(DQdPrevOrientations.begin(), DQdPrevOrientations.end(), 0.0) / static_cast<double>(DQdPrevOrientations.size());
 
                     dPrevWaveAngle = dAvgOrientationSoFar;
                  }
               }
 
               if (DQdPrevOrientations.size() == MAX_NUM_PREV_ORIENTATION_VALUES)
                  DQdPrevOrientations.pop_front();
 
               DQdPrevOrientations.push_back(dPrevWaveAngle);
            }
 
            // Go upwave along the previous cell's wave orientation to find the new boundary cell
            CGeom2DIPoint const PtiNew = PtiFollowWaveAngle(&PtiPrev, dPrevWaveAngle, dCorrection);
 
            // Get the coordinates of 'this' cell
            int const nX = PtiNew.nGetX();
            int const nY = PtiNew.nGetY();
 
            // Have we hit the edge of the valid part of the grid?
            if ((! bIsWithinValidGrid(&PtiNew)) || (m_pRasterGrid->m_Cell[nX][nY].bIsBoundingBoxEdge()))
            {
               // Yes we have
               bHitEdge = true;
 
               LogStream << m_ulIter << ": \tcoast " << nCoast << " shadow boundary " << nStartPoint << " hit edge cell at [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "}" << endl;
 
               continue;
            }
 
            // Have we been to this cell before?
            if (ILShadowBoundary.bIsPresent(nX, nY))
            {
               // We have, so we are in a loop. Abandon this shadow line
               bInLoop = true;
               break;
            }
 
            // OK so far. Have we hit a sea cell yet?
            if ((nDist > MAX_LAND_LENGTH_OF_SHADOW_ZONE_LINE) && (! bHitSea))
            {
               if (m_pRasterGrid->m_Cell[nX][nY].bIsInContiguousSea())
                  bHitSea = true;
               else
               {
                  if (nDist >= MAX_LAND_LENGTH_OF_SHADOW_ZONE_LINE)
                  {
                     // If we have travelled MAX_LAND_LENGTH_OF_SHADOW_ZONE_LINE cells without hitting sea, then abandon this shadow boundary
                     bStillInland = true;
                     break;
                  }
               }
            }
 
            // Store the coordinates of every cell which we cross
            ILShadowBoundary.Append(&PtiNew);
 
            // LogStream << m_ulIter << ": at [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "}" << endl;
 
            // Having hit sea, have we now hit we hit a coast point? Note that two diagonal(ish) raster lines can cross each other without any intersection, so must also test an adjacent cell for intersection (does not matter which adjacent cell)
            if (bHitSea)
            {
               if (m_pRasterGrid->m_Cell[nX][nY].bIsCoastline() || (bIsWithinValidGrid(nX, nY + 1) && m_pRasterGrid->m_Cell[nX][nY + 1].bIsCoastline()))
               {
                  bHitCoast = true;
 
                  // if (m_nLogFileDetail >= LOG_FILE_ALL)
                  //    LogStream << m_ulIter << ": coast " << nCoast << " possible shadow boundary from start point " << nStartPoint << " hit the coast at [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "}" << endl;
               }
            }
 
            // For next time
            PtiPrev = PtiNew;
            nDist++;
         }
 
         if (bInLoop)
         {
            // Shadow line loops, so abandon it
            if (m_nLogFileDetail >= LOG_FILE_ALL)
               LogStream << m_ulIter << ": \tcoast " << nCoast << " possible shadow boundary from start point " << nStartPoint << " forms a loop, abandoning. Starts at [" << ILShadowBoundary[0].nGetX() << "][" << ILShadowBoundary[0].nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILShadowBoundary[0].nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary[0].nGetY()) << "} abandoned at [" << ILShadowBoundary.Back().nGetX() << "][" << ILShadowBoundary.Back().nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILShadowBoundary.Back().nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary.Back().nGetY()) << "}" << endl;
 
            continue;
         }
 
         if (bStillInland)
         {
            // Shadow line is still inland after crossing MAX_LAND_LENGTH_OF_SHADOW_ZONE_LINE calls
            // if (m_nLogFileDetail >= LOG_FILE_ALL)
            //    LogStream << m_ulIter << ": coast " << nCoast << " possible shadow boundary from start point " << nStartPoint << " is still inland after crossing " << MAX_LAND_LENGTH_OF_SHADOW_ZONE_LINE << " cells, abandoning. Starts at [" << ILShadowBoundary[0].nGetX() << "][" << ILShadowBoundary[0].nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILShadowBoundary[0].nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary[0].nGetY()) << "} abandoned at [" << ILShadowBoundary.Back().nGetX() << "][" << ILShadowBoundary.Back().nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILShadowBoundary.Back().nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary.Back().nGetY()) << "}" << endl;
 
            continue;
         }
 
         if (bHitCoast)
         {
            // The shadow zone boundary has hit a coast, but is the shadow zone line trivially short?
            double const dShadowLen = dGetDistanceBetween(&ILShadowBoundary[0], &ILShadowBoundary.Back()) * m_dCellSide;
 
            if (dShadowLen < MIN_LENGTH_OF_SHADOW_ZONE_LINE)
            {
               // Too short, so forget about it
               if (m_nLogFileDetail >= LOG_FILE_ALL)
                  LogStream << m_ulIter << ": \tcoast " << nCoast << ", possible shadow boundary from start point " << nStartPoint << " is too short. Length " << dShadowLen << " m minimum length " << MIN_LENGTH_OF_SHADOW_ZONE_LINE << " m. Starts at [" << ILShadowBoundary[0].nGetX() << "][" << ILShadowBoundary[0].nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILShadowBoundary[0].nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary[0].nGetY()) << "} hits coast at [" << ILShadowBoundary.Back().nGetX() << "][" << ILShadowBoundary.Back().nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILShadowBoundary.Back().nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary.Back().nGetY()) << "}" << endl;
 
               continue;
            }
 
            // We've found a valid shadow zone. Check the last point in the shadow boundary. Note that occasionally this last cell is not 'above' a cell but is above one of its neighbouring cells is: in which case, replace the last point in the shadow boundary with the coordinates of this neighbouring cell
            int const nShadowBoundaryCoastPoint = m_VCoast[nCoast].nGetCoastPointGivenCell(&ILShadowBoundary.Back());
 
            if (nShadowBoundaryCoastPoint == INT_NODATA)
            {
               // // Could not find a neighbouring cell which is 'under' the coastline
               // if (m_nLogFileDetail >= LOG_FILE_ALL)
               //    LogStream << m_ulIter << ": coast " << nCoast << ", no coast point under {" << dGridCentroidXToExtCRSX(ILShadowBoundary.Back().nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary.Back().nGetY()) << "}" << endl;
 
               // TODO 004 Need to fix this, for the moment just abandon this shadow zone and carry on
               continue;
               // return RTN_ERR_NO_CELL_UNDER_COASTLINE;
            }
 
            // Now store the shadow zone boundary information
            VILShadowBoundary.push_back(ILShadowBoundary);
            VnShadowBoundaryStartCoastPoint.push_back(VnPossibleShadowBoundaryCoastPoint[nStartPoint]);
            VnShadowBoundaryEndCoastPoint.push_back(nShadowBoundaryCoastPoint);
 
            if (m_nLogFileDetail >= LOG_FILE_ALL)
               LogStream << m_ulIter << ": \tcoast " << nCoast << " coast " << nCoast << " shadow boundary start point " << nStartPoint << " is valid shadow zone. Start [" << ILShadowBoundary[0].nGetX() << "][" << ILShadowBoundary[0].nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILShadowBoundary[0].nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary[0].nGetY()) << "} hits coast at [" << ILShadowBoundary.Back().nGetX() << "][" << ILShadowBoundary.Back().nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILShadowBoundary.Back().nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary.Back().nGetY()) << "} coast point " << nShadowBoundaryCoastPoint << " is shadow zone " << VnShadowBoundaryEndCoastPoint.size() - 1 << endl;
         }
 
         if (bHitEdge)
         {
            if (CREATE_SHADOW_ZONE_IF_HITS_GRID_EDGE)
            {
               // We are creating shadow zones if we hit the grid edge. But is the shadow zone line trivially short?
               double const dShadowLen = dGetDistanceBetween(&ILShadowBoundary[0], &ILShadowBoundary.Back()) * m_dCellSide;
 
               if (dShadowLen < MIN_LENGTH_OF_SHADOW_ZONE_LINE)
               {
                  // Too short, so forget about it
                  if (m_nLogFileDetail >= LOG_FILE_ALL)
                     LogStream << m_ulIter << ": \tcoast " << nCoast << " Possible shadow boundary start point " << nStartPoint << " too short. Length " << dShadowLen << " m minimum length is " << MIN_LENGTH_OF_SHADOW_ZONE_LINE << " m. Starts at [" << ILShadowBoundary[0].nGetX() << "][" << ILShadowBoundary[0].nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILShadowBoundary[0].nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary[0].nGetY()) << "} hits grid edge at [" << ILShadowBoundary.Back().nGetX() << "][" << ILShadowBoundary.Back().nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILShadowBoundary.Back().nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary.Back().nGetY()) << "}" << endl;
 
                  continue;
               }
 
               // We've found a valid grid-edge shadow zone, but we need a distance (in cells) between the shadow boundary start and the 'virtual' shadow boundary end: this is the off-grid point where the shadow boundary would have intersected the coastline, if the grid were big enough. This is of course unknowable. So as a best guess, we choose the shorter of the two distances between the point where the shadow boundary hits the valid edge of the grid, and the start or end of the coast
               // int nCoastSize = m_VCoast[nCoast].nGetCoastlineSize();
               CGeom2DIPoint const PtiCoastStart = *m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(0);
               CGeom2DIPoint const PtiCoastEnd = *m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nCoastSize - 1);
 
               int const nDistance = nRound(tMin(dGetDistanceBetween(&ILShadowBoundary.Back(), &PtiCoastStart), dGetDistanceBetween(&ILShadowBoundary.Back(), &PtiCoastEnd)));
 
               // Now store the shadow zone boundary information
               VILShadowBoundary.push_back(ILShadowBoundary);
               VnShadowBoundaryStartCoastPoint.push_back(VnPossibleShadowBoundaryCoastPoint[nStartPoint]);
               VnShadowBoundaryEndCoastPoint.push_back(nDistance);
 
               // if (m_nLogFileDetail >= LOG_FILE_ALL)
               //    LogStream << m_ulIter << ": coast " << nCoast << " possible shadow boundary from start point " << nStartPoint << " defines a valid shadow zone. Start point [" << ILShadowBoundary[0].nGetX() << "][" << ILShadowBoundary[0].nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILShadowBoundary[0].nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary[0].nGetY()) << "}, hit grid edge at [" << ILShadowBoundary.Back().nGetX() << "][" << ILShadowBoundary.Back().nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILShadowBoundary.Back().nGetX()) << ", " << dGridCentroidYToExtCRSY(ILShadowBoundary.Back().nGetY()) << "}. Best-guess length of the shadow boundary is " << nDistance << " cells. Will be shadow zone " << VnShadowBoundaryEndCoastPoint.size() - 1 << endl;
            }
            else
            {
               // We are not creating shadow zones if we hit the grid edge
               if (m_nLogFileDetail >= LOG_FILE_ALL)
                  LogStream << m_ulIter << ": \tcoast " << nCoast << " possible shadow boundary from start point " << nStartPoint << " hits a grid edge: ignored. Sarts at [" << ILShadowBoundary[0].nGetX() << "][" << ILShadowBoundary[0].nGetY() << "]" << endl;
            }
         }
      }
 
      // =========================================================================================================================
      // The third stage: store the shadow zone boundary, cell-by-cell fill the shadow zone, then change wave properties by sweeping the shadow zone and the area downdrift from the shadow zone
      for (unsigned int nZone = 0; nZone < VILShadowBoundary.size(); nZone++)
      {
         // if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
         //    LogStream << m_ulIter << ": coast " << nCoast << ", processing shadow zone " << nZone << " of " << VILShadowBoundary.size() << endl;
 
         int const nShadowLineLen = VILShadowBoundary[nZone].nGetSize();
 
         // The vector shadow boundary (external CRS)
         CGeomLine LBoundary;
 
         // And the same with grid CRS
         CGeomILine LIBoundary;
 
         for (int nn = 0; nn < nShadowLineLen; nn++)
         {
            int const nTmpX = VILShadowBoundary[nZone][nn].nGetX();
            int const nTmpY = VILShadowBoundary[nZone][nn].nGetY();
 
            // Mark the cells as shadow zone boundary
            m_pRasterGrid->m_Cell[nTmpX][nTmpY].SetShadowZoneBoundary();
 
            // If this is a sea cell, mark the shadow zone boundary cell as being in the shadow zone, but not yet processed (a -ve number)
            if (m_pRasterGrid->m_Cell[nTmpX][nTmpY].bIsInContiguousSea())
               m_pRasterGrid->m_Cell[nTmpX][nTmpY].SetShadowZoneNumber(-(nZone + 1));
 
            // If not already there, append this values to the two shadow boundary vectors
            LBoundary.AppendIfNotPrevious(dGridCentroidXToExtCRSX(nTmpX), dGridCentroidYToExtCRSY(nTmpY));
            LIBoundary.AppendIfNotPrevious(nTmpX, nTmpY);
 
            // LogStream << m_ulIter << ": coast " << nCoast << " shadow zone " << nZone << ", which starts at [" << nTmpX << "][" << nTmpY << "] = {" << dGridCentroidXToExtCRSX(nTmpX) << ", " << dGridCentroidYToExtCRSY(nTmpY) << "} has cell [" << nTmpX << "][" << nTmpY << "] marked as shadow zone boundary" << endl;
         }
 
         // Put the ext CRS vector shadow boundary into reverse sequence (i.e. start point is last)
         LBoundary.Reverse();
 
         // Store the reversed ext CRS shadow zone boundary
         m_VCoast[nCoast].AppendShadowBoundary(&LBoundary);
 
         int const nStartX = VILShadowBoundary[nZone][0].nGetX();
         int const nStartY = VILShadowBoundary[nZone][0].nGetY();
         int const nEndX = VILShadowBoundary[nZone][nShadowLineLen - 1].nGetX();
         int const nEndY = VILShadowBoundary[nZone][nShadowLineLen - 1].nGetY();
 
         // Grid CRS
         CGeom2DIPoint const PtiStart(nStartX, nStartY);
         CGeom2DIPoint const PtiEnd(nEndX, nEndY);
 
         // Cell-by-cell fill the shadow zone: start by finding the centroid
         if (VnShadowBoundaryEndCoastPoint[nZone] > VnShadowBoundaryStartCoastPoint[nZone])
         {
            // The shadow boundary endpoint is down-coast from the shadow boundary start point
            int const nStart = tMax(VnShadowBoundaryStartCoastPoint[nZone], 0);
            int const nEnd = tMin(VnShadowBoundaryEndCoastPoint[nZone], m_VCoast[nCoast].nGetCoastlineSize());
 
            for (int nn = nStart; nn < nEnd; nn++)
            {
               // Append the coastal portion of the shadow zone boundary to the grid CRS vector
               LIBoundary.Append(m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nn));
               // LogStream << "Coast point A " << nn << " [" << m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nn)->nGetX() << "][" << m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nn)->nGetY() << "]" << endl;
            }
         }
 
         else
         {
            // The shadow boundary endpoint is up-coast from the shadow boundary start point
            int const nStart = tMin(VnShadowBoundaryEndCoastPoint[nZone], m_VCoast[nCoast].nGetCoastlineSize() - 1);
            int const nEnd = tMax(VnShadowBoundaryStartCoastPoint[nZone], 0);
 
            for (int nn = nStart; nn >= nEnd; nn--)
            {
               // Append the coastal portion of the shadow zone boundary to the grid CRS vector
               LIBoundary.Append(m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nn));
               // LogStream << "Coast point B " << nn << " [" << m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nn)->nGetX() << "][" << m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nn)->nGetY() << "]" << endl;
            }
         }
 
         //          // DEBUG CODE =======================================================================================================================
         // LogStream << "FIRST" << endl;
         // for (int k = 0; k < LIBoundary.nGetSize(); k++)
         // {
         // CGeom2DIPoint PtiTmp = *LIBoundary.pPtiGetAt(k);
         // LogStream << k << " [" << PtiTmp.nGetX() << "][" << PtiTmp.nGetY() << "]" << endl;
         // }
         // LogStream << endl;
         //          // DEBUG CODE =======================================================================================================================
 
         // Calculate the centroid
         CGeom2DIPoint const PtiCentroid = PtiPolygonCentroid(LIBoundary.pPtiVGetPoints());
 
         if (bIsWithinValidGrid(&PtiCentroid)) // Safety check
         {
            int const nRet = nCellByCellFillShadowZone(nCoast, nZone, &PtiCentroid, &PtiStart, &PtiEnd);
 
            if (nRet != RTN_OK)
            {
               // Could not find start point for cell-by-cell fill. How serious we judge this to be depends on the length of the shadow zone line
               if (nShadowLineLen < MAX_LEN_SHADOW_LINE_TO_IGNORE)
               {
                  if (m_nLogFileDetail >= LOG_FILE_ALL)
                     LogStream << m_ulIter << ": " << WARN << "could not find start point for cell-by-cell fill of shadow zone " << nZone << " but continuing simulation because this is a small shadow zone (shadow line length = " << nShadowLineLen << " cells)" << endl;
 
                  continue;
               }
 
               else
               {
                  LogStream << m_ulIter << ": " << ERR << "could not find start point for cell-by-cell fill of shadow zone " << nZone << " (shadow line length = " << nShadowLineLen << " cells)" << endl;
                  return nRet;
               }
            }
 
            // Sweep the shadow zone, changing wave orientation and height
            DoShadowZoneAndDownDriftZone(nCoast, nZone, VnShadowBoundaryStartCoastPoint[nZone], VnShadowBoundaryEndCoastPoint[nZone]);
         }
      }
   }
 
   return RTN_OK;
}
 
//===============================================================================================================================
//===============================================================================================================================
int CSimulation::nCellByCellFillShadowZone(int const nCoast, int const nZone, CGeom2DIPoint const* pPtiCentroid, CGeom2DIPoint const* pPtiShadowBoundaryStart, CGeom2DIPoint const* pPtiShadowBoundaryEnd)
{
   // Is the centroid a sea cell?
   bool bStartPointOK = true;
   bool bAllPointNotSea = true;
   CGeom2DIPoint PtiFloodFillStart = *pPtiCentroid;
 
   if (! m_pRasterGrid->m_Cell[PtiFloodFillStart.nGetX()][PtiFloodFillStart.nGetY()].bIsInContiguousSea())
   {
      // No it isn't: so try to find a cell that is
      bStartPointOK = false;
      double dWeight = 0.05;
 
      while ((! bStartPointOK) && (dWeight < 1))
      {
         // Find a start point for the Cell-by-cell fill. Because shadow zones are generally triangular, start by choosing a low weighting so that the start point is close to the centroid, but a bit towards the coast. If this doesn't work, go further coastwards
         PtiFloodFillStart = PtiWeightedAverage(pPtiShadowBoundaryEnd, pPtiCentroid, dWeight);
 
         // Safety check
         if (PtiFloodFillStart == *pPtiCentroid)
         {
            dWeight += 0.05;
            continue;
         }
 
         // Safety check
         if (! bIsWithinValidGrid(&PtiFloodFillStart))
         {
            if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
               LogStream << m_ulIter << ": " << ERR << "start point [" << PtiFloodFillStart.nGetX() << "][" << PtiFloodFillStart.nGetY() << "] = {" << dGridCentroidXToExtCRSX(PtiFloodFillStart.nGetX()) << ", " << dGridCentroidYToExtCRSY(PtiFloodFillStart.nGetY()) << "} for cell-by-cell fill of shadow zone is outside grid" << endl;
 
            return RTN_ERR_SHADOW_ZONE_FLOOD_FILL_NOGRID;
         }
 
         if (m_pRasterGrid->m_Cell[PtiFloodFillStart.nGetX()][PtiFloodFillStart.nGetY()].bIsInContiguousSea())
         {
            // Start point is a sea cell, all OK
            bStartPointOK = true;
            bAllPointNotSea = false;
         }
         else
         {
            // Start point is not a sea cell
            if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
               LogStream << m_ulIter << ": \tcoast " << nCoast << " shadow zone cell-by-cell fill start point [" << PtiFloodFillStart.nGetX() << "][" << PtiFloodFillStart.nGetY() << "] = {" << dGridCentroidXToExtCRSX(PtiFloodFillStart.nGetX()) << ", " << dGridCentroidYToExtCRSY(PtiFloodFillStart.nGetY()) << "} is NOT a sea cell for shadow boundary from cape point [" << pPtiShadowBoundaryStart->nGetX() << "][" << pPtiShadowBoundaryStart->nGetY() << "] = {" << dGridCentroidXToExtCRSX(pPtiShadowBoundaryStart->nGetX()) << ", " << dGridCentroidYToExtCRSY(pPtiShadowBoundaryStart->nGetY()) << "} to [" << pPtiShadowBoundaryEnd->nGetX() << "][" << pPtiShadowBoundaryEnd->nGetY() << "] = {" << dGridCentroidXToExtCRSX(pPtiShadowBoundaryEnd->nGetX()) << ", " << dGridCentroidYToExtCRSY(pPtiShadowBoundaryEnd->nGetY()) << "}, dWeight = " << dWeight << endl;
 
            dWeight += 0.05;
         }
      }
   }
 
   if ((! bStartPointOK) && (! bAllPointNotSea))
   {
      if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
         LogStream << m_ulIter << ": \tcoast " << nCoast << " " << ERR << "could not find shadow zone cell-by-cell fill start point" << endl;
 
      return RTN_ERR_SHADOW_ZONE_FLOOD_START_POINT;
   }
 
   if (m_nLogFileDetail >= LOG_FILE_ALL)
      LogStream << m_ulIter << ": \tcoast " << nCoast << " shadow zone cell-by-cell fill start point [" << PtiFloodFillStart.nGetX() << "][" << PtiFloodFillStart.nGetY() << "] = {" << dGridCentroidXToExtCRSX(PtiFloodFillStart.nGetX()) << ", " << dGridCentroidYToExtCRSY(PtiFloodFillStart.nGetY()) << "} OK for shadow boundary from [" << pPtiShadowBoundaryStart->nGetX() << "][" << pPtiShadowBoundaryStart->nGetY() << "] = {" << dGridCentroidXToExtCRSX(pPtiShadowBoundaryStart->nGetX()) << ", " << dGridCentroidYToExtCRSY(pPtiShadowBoundaryStart->nGetY()) << "} to [" << pPtiShadowBoundaryEnd->nGetX() << "][" << pPtiShadowBoundaryEnd->nGetY() << "] = {" << dGridCentroidXToExtCRSX(pPtiShadowBoundaryEnd->nGetX()) << ", " << dGridCentroidYToExtCRSY(pPtiShadowBoundaryEnd->nGetY()) << "}" << endl;
 
   // All OK, so create an empty stack
   stack<CGeom2DIPoint> PtiStack;
 
   // We have a cell-by-cell fill start point so push this point onto the stack
   PtiStack.push(PtiFloodFillStart);
 
   // Then do the cell-by-cell fill: loop until there are no more cell coordinates on the stack
   while (! PtiStack.empty())
   {
      CGeom2DIPoint const Pti = PtiStack.top();
      PtiStack.pop();
 
      int
          nX = Pti.nGetX(),
          nY = Pti.nGetY();
 
      while ((nX >= 0) && m_pRasterGrid->m_Cell[nX][nY].bIsInContiguousSea() && (!m_pRasterGrid->m_Cell[nX][nY].bIsinThisShadowZone(-nZone - 1)) && (!m_pRasterGrid->m_Cell[nX][nY].bIsShadowZoneBoundary()) && (!m_pRasterGrid->m_Cell[nX][nY].bIsCoastline()))
         nX--;
 
      nX++;
 
      bool
          bSpanAbove = false,
          bSpanBelow = false;
 
      while ((nX < m_nXGridSize) && m_pRasterGrid->m_Cell[nX][nY].bIsInContiguousSea() && (!m_pRasterGrid->m_Cell[nX][nY].bIsinThisShadowZone(-nZone - 1)) && (!m_pRasterGrid->m_Cell[nX][nY].bIsShadowZoneBoundary()) && (!m_pRasterGrid->m_Cell[nX][nY].bIsCoastline()))
      {
         // Mark the cell as being in the shadow zone but not yet processed (a -ve number, with -1 being zone 1)
         m_pRasterGrid->m_Cell[nX][nY].SetShadowZoneNumber(-nZone - 1);
 
         // LogStream << m_ulIter << ": [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "} marked as shadow zone" << endl;
 
         if ((! bSpanAbove) && (nY > 0) && m_pRasterGrid->m_Cell[nX][nY].bIsInContiguousSea() && (!m_pRasterGrid->m_Cell[nX][nY - 1].bIsinThisShadowZone(-nZone - 1)) && (!m_pRasterGrid->m_Cell[nX][nY - 1].bIsShadowZoneBoundary()) && (!m_pRasterGrid->m_Cell[nX][nY - 1].bIsCoastline()))
         {
            PtiStack.push(CGeom2DIPoint(nX, nY - 1));
            bSpanAbove = true;
         }
 
         else if (bSpanAbove && (nY > 0) && ((!m_pRasterGrid->m_Cell[nX][nY - 1].bIsInContiguousSea()) || m_pRasterGrid->m_Cell[nX][nY - 1].bIsinThisShadowZone(-nZone - 1) || m_pRasterGrid->m_Cell[nX][nY - 1].bIsShadowZoneBoundary() || m_pRasterGrid->m_Cell[nX][nY - 1].bIsCoastline()))
         {
            bSpanAbove = false;
         }
 
         if ((! bSpanBelow) && m_pRasterGrid->m_Cell[nX][nY].bIsInContiguousSea() && (nY < m_nYGridSize - 1) && (!m_pRasterGrid->m_Cell[nX][nY + 1].bIsinThisShadowZone(-nZone - 1)) && (!m_pRasterGrid->m_Cell[nX][nY + 1].bIsShadowZoneBoundary()) && (!m_pRasterGrid->m_Cell[nX][nY + 1].bIsCoastline()))
         {
            PtiStack.push(CGeom2DIPoint(nX, nY + 1));
            bSpanBelow = true;
         }
 
         else if (bSpanBelow && (nY < m_nYGridSize - 1) && ((!m_pRasterGrid->m_Cell[nX][nY + 1].bIsInContiguousSea()) || m_pRasterGrid->m_Cell[nX][nY + 1].bIsinThisShadowZone(-nZone - 1) || m_pRasterGrid->m_Cell[nX][nY + 1].bIsShadowZoneBoundary() || m_pRasterGrid->m_Cell[nX][nY + 1].bIsCoastline()))
         {
            bSpanBelow = false;
         }
 
         nX++;
      }
   }
 
   return RTN_OK;
}
 
//===============================================================================================================================
//===============================================================================================================================
void CSimulation::DoShadowZoneAndDownDriftZone(int const nCoast, int const nZone, int const nShadowBoundaryStartPoint, int const nShadowBoundaryEndPoint)
{
   int const nCoastSeaHand = m_VCoast[nCoast].nGetSeaHandedness();
   int nShadowZoneCoastToCapeSeaHand;
 
   if (nCoastSeaHand == LEFT_HANDED)
      nShadowZoneCoastToCapeSeaHand = RIGHT_HANDED;
 
   else
      nShadowZoneCoastToCapeSeaHand = LEFT_HANDED;
 
   // We will traverse the coastline from the start point of the shadow zone line, going toward the end point. Which direction is this?
   bool bSweepDownCoast = true;
 
   if (nShadowBoundaryEndPoint < nShadowBoundaryStartPoint)
      bSweepDownCoast = false;
 
   // Get the distance (in cells) from the shadow boundary start point to the shadow boundary end point, going along the coast
   int const nAlongCoastDistanceToShadowEndpoint = tAbs(nShadowBoundaryEndPoint - nShadowBoundaryStartPoint - 1);
 
   // Calculate the point on the coastline which is 2 * nAlongCoastDistanceToShadowEndpoint from the shadow boundary start point, this will be the end point of the downdrift zone. This point may be beyond the end of the coastline in either direction
   int nDownDriftEndPoint;
   int const nTotAlongCoastDistanceToDownDriftEndpoint = 2 * nAlongCoastDistanceToShadowEndpoint;
 
   if (bSweepDownCoast)
      nDownDriftEndPoint = nShadowBoundaryStartPoint + nTotAlongCoastDistanceToDownDriftEndpoint;
 
   else
      nDownDriftEndPoint = nShadowBoundaryStartPoint - nTotAlongCoastDistanceToDownDriftEndpoint;
 
   // Next find the actual (i.e. within-grid) end of the downdrift line
   CGeom2DIPoint PtiDownDriftEndPoint;
 
   // Is the downdrift end point beyond the start or end of the coastline?
   if (nDownDriftEndPoint < 0)
   {
      // Is beyond the start of the coastline
      int const nStartEdge = m_VCoast[nCoast].nGetStartEdge();
 
      if (nStartEdge == NORTH)
      {
         PtiDownDriftEndPoint.SetX(m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(0)->nGetX());
         PtiDownDriftEndPoint.SetY(nDownDriftEndPoint);
      }
 
      else if (nStartEdge == SOUTH)
      {
         PtiDownDriftEndPoint.SetX(m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(0)->nGetX());
         PtiDownDriftEndPoint.SetY(m_nYGridSize - nDownDriftEndPoint - 1);
      }
 
      else if (nStartEdge == WEST)
      {
         PtiDownDriftEndPoint.SetX(nDownDriftEndPoint);
         PtiDownDriftEndPoint.SetY(m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(0)->nGetY());
      }
 
      else if (nStartEdge == EAST)
      {
         PtiDownDriftEndPoint.SetX(m_nXGridSize - nDownDriftEndPoint - 1);
         PtiDownDriftEndPoint.SetY(m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(0)->nGetY());
      }
   }
 
   else if (nDownDriftEndPoint >= m_VCoast[nCoast].nGetCoastlineSize())
   {
      // Is beyond the end of the coastline
      int const nEndEdge = m_VCoast[nCoast].nGetEndEdge();
      int const nCoastSize = m_VCoast[nCoast].nGetCoastlineSize();
 
      if (nEndEdge == NORTH)
      {
         PtiDownDriftEndPoint.SetX(m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nCoastSize - 1)->nGetX());
         PtiDownDriftEndPoint.SetY(-nDownDriftEndPoint);
      }
 
      else if (nEndEdge == SOUTH)
      {
         PtiDownDriftEndPoint.SetX(m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nCoastSize - 1)->nGetX());
         PtiDownDriftEndPoint.SetY(m_nYGridSize + nDownDriftEndPoint);
      }
 
      else if (nEndEdge == WEST)
      {
         PtiDownDriftEndPoint.SetX(-nDownDriftEndPoint);
         PtiDownDriftEndPoint.SetY(m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nCoastSize - 1)->nGetY());
      }
 
      else if (nEndEdge == EAST)
      {
         PtiDownDriftEndPoint.SetX(m_nXGridSize + nDownDriftEndPoint);
         PtiDownDriftEndPoint.SetY(m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nCoastSize - 1)->nGetY());
      }
   }
 
   else
   {
      // Is on the coastline, so get the location (grid CRS)
      PtiDownDriftEndPoint = *m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nDownDriftEndPoint);
   }
 
   // Get the location (grid CRS) of the shadow boundary start point: this is also the start point of the downdrift boundary
   CGeom2DIPoint const* pPtiDownDriftBoundaryStartPoint = m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nShadowBoundaryStartPoint);
 
   // Now trace the down-drift boundary line: interpolate between cells by a simple DDA line algorithm, see http://en.wikipedia.org/wiki/Digital_differential_analyzer_(graphics_algorithm) Note that Bresenham's algorithm gave occasional gaps
   int const nXStart = pPtiDownDriftBoundaryStartPoint->nGetX();
   int const nYStart = pPtiDownDriftBoundaryStartPoint->nGetY();
   int const nXEnd = PtiDownDriftEndPoint.nGetX();
   int const nYEnd = PtiDownDriftEndPoint.nGetY();
 
   // Safety check
   if ((nXStart == nXEnd) && (nYStart == nYEnd))
      return;
 
   double const dXStart = dGridCentroidXToExtCRSX(nXStart);
   double const dYStart = dGridCentroidYToExtCRSY(nYStart);
   double const dXEnd = dGridCentroidXToExtCRSX(nXEnd);
   double const dYEnd = dGridCentroidYToExtCRSY(nYEnd);
   double dXInc = dXEnd - dXStart;
   double dYInc = dYEnd - dYStart;
   double const dLength = tMax(tAbs(dXInc), tAbs(dYInc));
 
   dXInc /= dLength;
   dYInc /= dLength;
 
   int nTotDownDriftBoundaryDistance = 0;
   double dX = nXStart;
   double dY = nYStart;
 
   CGeomLine LDownDriftBoundary;
 
   // Process each interpolated point
   for (int m = 0; m <= nRound(dLength); m++)
   {
      int const nX = nRound(dX);
      int const nY = nRound(dY);
 
      if (! bIsWithinValidGrid(nX, nY))
      {
         // Safety check
         break;
      }
 
      // OK, this is part of the downdrift boundary so store this coordinate and mark the cell
      CGeom2DPoint const PtThis(dGridCentroidXToExtCRSX(nX), dGridCentroidYToExtCRSY(nY));
 
      // Make sure we have not already stored this coordinate (can happen, due to rounding)
      if ((LDownDriftBoundary.nGetSize() == 0) || (PtThis != LDownDriftBoundary.pPtBack()))
      {
         // Store this coordinate
         LDownDriftBoundary.Append(&PtThis);
 
         // Mark the cell (a +ve number, same as the associated shadow zone number i.e. starting from 1)
         m_pRasterGrid->m_Cell[nX][nY].SetDownDriftZoneNumber(nZone + 1);
 
         // Increment the boundary length
         nTotDownDriftBoundaryDistance++;
 
         // LogStream << "DownDrift boundary [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "}" << endl;
 
         // And increment for next time
         if (dXEnd > dXStart)
            dX -= dXInc;
 
         else
            dX += dXInc;
 
         if (dYEnd > dYStart)
            dY += dYInc;
 
         else
            dY -= dYInc;
      }
   }
 
   // Store the downdrift boundary (external CRS), with the start point first
   m_VCoast[nCoast].AppendShadowDowndriftBoundary(&LDownDriftBoundary);
 
   // Compare the lengths of the along-coast and the along-downdrift boundaries. The increment will be 1 for the smaller of the two, will be > 1 for the larger of the two
   int nMaxDistance;
   double dAlongCoastIncrement = 1;
   double dDownDriftBoundaryIncrement = 1;
 
   if (nTotAlongCoastDistanceToDownDriftEndpoint < nTotDownDriftBoundaryDistance)
   {
      // The downdrift boundary distance is the larger, so change it
      dDownDriftBoundaryIncrement = static_cast<double>(nTotDownDriftBoundaryDistance) / nTotAlongCoastDistanceToDownDriftEndpoint;
      nMaxDistance = nTotDownDriftBoundaryDistance;
   }
 
   else
   {
      // The along-coast distance is the larger, so change it
      dAlongCoastIncrement = static_cast<double>(nTotAlongCoastDistanceToDownDriftEndpoint) / nTotDownDriftBoundaryDistance;
      nMaxDistance = nTotAlongCoastDistanceToDownDriftEndpoint;
   }
 
   double dCoastDistSoFar = 0;
   double dDownDriftBoundaryDistSoFar = 0;
 
   // Now traverse the along-coast line and the down-drift boundary line, but with different increments for each
   for (int n = 1; n < nMaxDistance - 1; n++)
   {
      dCoastDistSoFar += dAlongCoastIncrement;
      dDownDriftBoundaryDistSoFar += dDownDriftBoundaryIncrement;
 
      // LogStream << "dDownDriftBoundaryDistSoFar = " << dDownDriftBoundaryDistSoFar << " nTotDownDriftBoundaryDistance = " << nTotDownDriftBoundaryDistance << endl;
 
      if ((dCoastDistSoFar >= nTotAlongCoastDistanceToDownDriftEndpoint) || (dDownDriftBoundaryDistSoFar >= nTotDownDriftBoundaryDistance))
         break;
 
      bool bPastShadowEnd = false;
      int nAlongCoast;
 
      if (bSweepDownCoast)
      {
         nAlongCoast = nShadowBoundaryStartPoint + nRound(dCoastDistSoFar);
 
         if (nAlongCoast >= m_VCoast[nCoast].nGetCoastlineSize())
            break;
 
         if (nAlongCoast >= nShadowBoundaryEndPoint)
            bPastShadowEnd = true;
      }
 
      else
      {
         nAlongCoast = nShadowBoundaryStartPoint - nRound(dCoastDistSoFar);
 
         if (nAlongCoast < 0)
            break;
 
         if (nAlongCoast <= nShadowBoundaryEndPoint)
            bPastShadowEnd = true;
      }
 
      int const nAlongDownDriftBoundary = nRound(dDownDriftBoundaryDistSoFar);
 
      // LogStream << endl << m_ulIter << ": dCoastDistSoFar = " << dCoastDistSoFar << " (nTotAlongCoastDistanceToDownDriftEndpoint = " << nTotAlongCoastDistanceToDownDriftEndpoint << ") dDownDriftBoundaryDistSoFar = " << dDownDriftBoundaryDistSoFar << " (nTotDownDriftBoundaryDistance = " << nTotDownDriftBoundaryDistance << ")" << endl;
 
      // nAlongCoast = " << nAlongCoast << ", nShadowBoundaryEndPoint = " << nShadowBoundaryEndPoint << ",  << ", nAlongDownDriftBoundary = " << nAlongDownDriftBoundary << ", << endl;
 
      // Get the two endpoints of the linking line
      CGeom2DIPoint const* pPtiCoast = m_VCoast[nCoast].pPtiGetCellMarkedAsCoastline(nAlongCoast);
      int const nCoastX = pPtiCoast->nGetX();
      int const nCoastY = pPtiCoast->nGetY();
 
      int const nDownDriftX = nRound(dExtCRSXToGridX(LDownDriftBoundary[nAlongDownDriftBoundary].dGetX()));
 
      // Safety check
      if (nCoastX >= m_nXGridSize)
         continue;
 
      int const nDownDriftY = nRound(dExtCRSYToGridY(LDownDriftBoundary[nAlongDownDriftBoundary].dGetY()));
 
      // Safety check
      if (nCoastY >= m_nYGridSize)
         continue;
 
      // Safety check, in case the two points are identical (can happen due to rounding)
      if ((nCoastX == nDownDriftX) && (nCoastY == nDownDriftY))
      {
         if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
            LogStream << m_ulIter << ": \tcoast " << nCoast << " coast point and downdrift boundary point [" << nCoastX << "][" << nCoastY << "] = {" << dGridCentroidXToExtCRSX(nCoastX) << ", " << dGridCentroidYToExtCRSY(nCoastY) << "} are identical, ignoring" << endl;
 
         continue;
      }
 
      // Traverse the linking line, interpolating between cells by a simple DDA line algorithm, see http://en.wikipedia.org/wiki/Digital_differential_analyzer_(graphics_algorithm)
      dXInc = nDownDriftX - nCoastX;
      dYInc = nDownDriftY - nCoastY;
      double const dLinkingLineLength = tMax(tAbs(dXInc), tAbs(dYInc));
 
      dXInc /= dLinkingLineLength;
      dYInc /= dLinkingLineLength;
 
      dX = nCoastX,
      dY = nCoastY;
 
      // Process each interpolated point along the linking line
      int nXLast = -1;
      int nYLast = -1;
      int nShadowZoneLength = 0;
      vector<int> VnShadowCellX, VnShadowCellY;
 
      for (int m = 0; m < dLinkingLineLength; m++)
      {
         int const nX = nRound(dX);
         int const nY = nRound(dY);
 
         // Check to see if we just processed this point, can happen due to rounding
         if ((nX == nXLast) && (nY == nYLast))
         {
            // LogStream << m_ulIter << ": n = " << n << ", m = " << m << ", dLinkingLineLength = " << dLinkingLineLength << ", dCoastDistSoFar = " << dCoastDistSoFar << " (nTotAlongCoastDistanceToDownDriftEndpoint = " << nTotAlongCoastDistanceToDownDriftEndpoint << "), dDownDriftBoundaryDistSoFar = " << dDownDriftBoundaryDistSoFar << " (nTotDownDriftBoundaryDistance = " << nTotDownDriftBoundaryDistance << ") same as last point at [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "}" << endl;
 
            // Set for next time
            // nXLast = nX;
            // nYLast = nY;
            dX += dXInc;
            dY += dYInc;
 
            continue;
         }
 
         // Outside valid grid?
         if (! bIsWithinValidGrid(nX, nY))
         {
            // LogStream << m_ulIter << ": n = " << n << ", m = " << m << ", dLinkingLineLength = " << dLinkingLineLength << ", dCoastDistSoFar = " << dCoastDistSoFar << " (nTotAlongCoastDistanceToDownDriftEndpoint = " << nTotAlongCoastDistanceToDownDriftEndpoint << "), dDownDriftBoundaryDistSoFar = " << dDownDriftBoundaryDistSoFar << " (nTotDownDriftBoundaryDistance = " << nTotDownDriftBoundaryDistance << ") outside valid grid at [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "}" << endl;
 
            // Set for next time
            nXLast = nX;
            nYLast = nY;
            dX += dXInc;
            dY += dYInc;
 
            continue;
         }
 
         // Not a sea cell?
         if (! m_pRasterGrid->m_Cell[nX][nY].bIsInContiguousSea())
         {
            // Not a sea cell
            // LogStream << m_ulIter << ": n = " << n << ", m = " << m << ", dLinkingLineLength = " << dLinkingLineLength << ", dCoastDistSoFar = " << dCoastDistSoFar << " (nTotAlongCoastDistanceToDownDriftEndpoint = " << nTotAlongCoastDistanceToDownDriftEndpoint << "), dDownDriftBoundaryDistSoFar = " << dDownDriftBoundaryDistSoFar << " (nTotDownDriftBoundaryDistance = " << nTotDownDriftBoundaryDistance << ") not a sea cell at [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "}" << endl;
 
            // Set for next time
            nXLast = nX;
            nYLast = nY;
            dX += dXInc;
            dY += dYInc;
 
            continue;
         }
 
         // Have we gone past the point where the shadow boundary meets the coast (i.e. the shadow boundary end point)?
         if (! bPastShadowEnd)
         {
            // We have not, so the linking line has two parts: one between the coast and the shadow boundary, one between the shadow boundary and the downdrift boundary
            bool bInShadowZone = true;
 
            if (! m_pRasterGrid->m_Cell[nX][nY].bIsinAnyShadowZone())
            {
               // We have left the shadow zone
               // LogStream << "[" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "} LEFT SHADOW ZONE" << endl;
 
               bInShadowZone = false;
 
               // Go back over stored cell coords and set their wave properties
               for (unsigned int mm = 0; mm < VnShadowCellX.size(); mm++)
               {
                  // Process this shadow zone cell
                  ProcessShadowZoneCell(VnShadowCellX[mm], VnShadowCellY[mm], nShadowZoneCoastToCapeSeaHand, pPtiCoast, VnShadowCellX.back(), VnShadowCellY.back(), nZone);
 
                  // Also process adjacent cells
                  if (mm > 0)
                  {
                     CGeom2DIPoint const PtiLeft = PtiGetPerpendicular(VnShadowCellX[mm], VnShadowCellY[mm], VnShadowCellX[mm - 1], VnShadowCellY[mm - 1], 1, RIGHT_HANDED);
                     CGeom2DIPoint const PtiRight = PtiGetPerpendicular(VnShadowCellX[mm], VnShadowCellY[mm], VnShadowCellX[mm - 1], VnShadowCellY[mm - 1], 1, LEFT_HANDED);
 
                     if (bIsWithinValidGrid(&PtiLeft))
                        ProcessShadowZoneCell(PtiLeft.nGetX(), PtiLeft.nGetY(), nShadowZoneCoastToCapeSeaHand, pPtiCoast, VnShadowCellX.back(), VnShadowCellY.back(), nZone);
 
                     if (bIsWithinValidGrid(&PtiRight))
                        ProcessShadowZoneCell(PtiRight.nGetX(), PtiRight.nGetY(), nShadowZoneCoastToCapeSeaHand, pPtiCoast, VnShadowCellX.back(), VnShadowCellY.back(), nZone);
                  }
               }
            }
 
            if (bInShadowZone)
            {
               // Save coords for later
               VnShadowCellX.push_back(nX);
               VnShadowCellY.push_back(nY);
 
               nShadowZoneLength++;
            }
            else
            {
               // In downdrift zone
 
               // LogStream << m_ulIter << ": n = " << n << ", m = " << m << ", dLinkingLineLength = " << dLinkingLineLength << ", dCoastDistSoFar = " << dCoastDistSoFar << " (nTotAlongCoastDistanceToDownDriftEndpoint = " << nTotAlongCoastDistanceToDownDriftEndpoint << "), dDownDriftBoundaryDistSoFar = " << dDownDriftBoundaryDistSoFar << " (nTotDownDriftBoundaryDistance = " << nTotDownDriftBoundaryDistance << ") has [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "} in downdrift zone" << endl;
 
               // Process this downdrift cell
               ProcessDownDriftCell(nX, nY, (m - nShadowZoneLength), (dLinkingLineLength - nShadowZoneLength), nZone);
 
               // Also process adjacent cells
               CGeom2DIPoint const PtiLeft = PtiGetPerpendicular(nX, nY, nXLast, nYLast, 1, RIGHT_HANDED);
               CGeom2DIPoint const PtiRight = PtiGetPerpendicular(nX, nY, nXLast, nYLast, 1, LEFT_HANDED);
 
               if (bIsWithinValidGrid(&PtiLeft))
                  ProcessDownDriftCell(PtiLeft.nGetX(), PtiLeft.nGetY(), (m - nShadowZoneLength), (dLinkingLineLength - nShadowZoneLength), nZone);
 
               if (bIsWithinValidGrid(&PtiRight))
                  ProcessDownDriftCell(PtiRight.nGetX(), PtiRight.nGetY(), (m - nShadowZoneLength), (dLinkingLineLength - nShadowZoneLength), nZone);
            }
         }
         else
         {
            // We have, so the linking line has only one part: between the coast and the downdrift boundary.
 
            // LogStream << m_ulIter << ": n = " << n << ", m = " << m << ", dLinkingLineLength = " << dLinkingLineLength << ", dCoastDistSoFar = " << dCoastDistSoFar << " (nTotAlongCoastDistanceToDownDriftEndpoint = " << nTotAlongCoastDistanceToDownDriftEndpoint << "), dDownDriftBoundaryDistSoFar = " << dDownDriftBoundaryDistSoFar << " (nTotDownDriftBoundaryDistance = " << nTotDownDriftBoundaryDistance << ") has [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "} in downdrift zone" << endl;
 
            // Process this downdrift cell
            ProcessDownDriftCell(nX, nY, m, dLinkingLineLength, nZone);
 
            // Also process adjacent cells
            if ((nXLast != -1) && (nYLast != -1))
            {
               CGeom2DIPoint const PtiLeft = PtiGetPerpendicular(nX, nY, nXLast, nYLast, 1, RIGHT_HANDED);
               CGeom2DIPoint const PtiRight = PtiGetPerpendicular(nX, nY, nXLast, nYLast, 1, LEFT_HANDED);
 
               if (bIsWithinValidGrid(&PtiLeft))
                  ProcessDownDriftCell(PtiLeft.nGetX(), PtiLeft.nGetY(), m, dLinkingLineLength, nZone);
 
               if (bIsWithinValidGrid(&PtiRight))
                  ProcessDownDriftCell(PtiRight.nGetX(), PtiRight.nGetY(), m, dLinkingLineLength, nZone);
            }
         }
 
         // Set for next time
         nXLast = nX;
         nYLast = nY;
         dX += dXInc;
         dY += dYInc;
      }
   }
}
 
//===============================================================================================================================
//===============================================================================================================================
void CSimulation::ProcessDownDriftCell(int const nX, int const nY, int const nTraversed, double const dTotalToTraverse, int const nZone)
{
   // Get the pre-existing (i.e. shore-parallel) wave height
   double const dWaveHeight = m_pRasterGrid->m_Cell[nX][nY].dGetWaveHeight();
 
   if (bFPIsEqual(dWaveHeight, DBL_NODATA, TOLERANCE))
   {
      // Is not a sea cell
      // LogStream << m_ulIter << ": [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "} ignored, not a sea cell" << endl;
 
      return;
   }
 
   int nZoneCode = m_pRasterGrid->m_Cell[nX][nY].nGetShadowZoneNumber();
 
   if (nZoneCode == (nZone + 1))
   {
      // This cell is in the associated shadow zone, so don't change it
      // LogStream << m_ulIter << ": [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "} ignored, is in associated shadow zone (" << nZone+1 << ")" << endl;
 
      return;
   }
 
   if (nZoneCode < 0)
   {
      // This cell is in a shadow zone but is not yet processed, so don't change it
      // LogStream << m_ulIter << ": [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "} ignored, is an unprocessed cell in shadow zone " << nZoneCode << endl;
 
      return;
   }
 
   nZoneCode = m_pRasterGrid->m_Cell[nX][nY].nGetDownDriftZoneNumber();
 
   if (nZoneCode == (nZone + 1))
   {
      // We have already processed this cell for this downdrift zone
      // LogStream << m_ulIter << ": [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "} ignored, already done for this down-drift zone " << nZone+1 << endl;
 
      return;
   }
 
   // OK, we are downdrift of the shadow zone area and have not yet processed this cell for this zone, so mark it
   m_pRasterGrid->m_Cell[nX][nY].SetDownDriftZoneNumber(nZone + 1);
 
   // Equation 14 from Hurst et al. TODO 056 Check this! Could not get this to work (typo in paper?), so used the equation below instead
   // double dKp = 0.5 * (1.0 - sin((PI * 90.0 * nSweep) / (180.0 * nSweepLength)));
   double const dKp = 0.5 + (0.5 * sin((PI * nTraversed) / (2.0 * dTotalToTraverse)));
 
   // Set the modified wave height
   m_pRasterGrid->m_Cell[nX][nY].SetWaveHeight(dKp * dWaveHeight);
 
   // LogStream << m_ulIter << ": [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "}, nTraversed = " << nTraversed << " dTotalToTraverse = " << dTotalToTraverse << " fraction traversed = " << nTraversed / dTotalToTraverse << endl << "m_pRasterGrid->m_Cell[" << nX << "][" << nY << "].dGetCellDeepWaterWaveHeight() = " << m_pRasterGrid->m_Cell[nX][nY].dGetCellDeepWaterWaveHeight() << " m, original dWaveHeight = " << dWaveHeight << " m, dKp = " << dKp << ", modified wave height = " << dKp * dWaveHeight << " m" << endl << endl;
}
 
//===============================================================================================================================
//===============================================================================================================================
void CSimulation::ProcessShadowZoneCell(int const nX, int const nY, int const nShadowZoneCoastToCapeSeaHand, CGeom2DIPoint const* pPtiCoast, int const nShadowEndX, int const nShadowEndY, int const nZone)
{
   int const nZoneCode = m_pRasterGrid->m_Cell[nX][nY].nGetShadowZoneNumber();
 
   if (nZoneCode == (-nZone - 1))
   {
      // OK, we are in the shadow zone and have not already processed this cell, so mark it (a +ve number, starting from 1)
      m_pRasterGrid->m_Cell[nX][nY].SetShadowZoneNumber(nZone + 1);
 
      // Next calculate wave angle here: first calculate dOmega, the signed angle subtended between this end point and the start point, and this end point and the end of the shadow boundary
      CGeom2DIPoint const PtiThis(nX, nY);
      CGeom2DIPoint const PtiShadowBoundary(nShadowEndX, nShadowEndY);
      double const dOmega = 180 * dAngleSubtended(pPtiCoast, &PtiThis, &PtiShadowBoundary) / PI;
 
      // If dOmega is 90 degrees or more in either direction, set both wave angle and wave height to zero
      if (tAbs(dOmega) >= 90)
      {
         m_pRasterGrid->m_Cell[nX][nY].SetWaveAngle(0);
         m_pRasterGrid->m_Cell[nX][nY].SetWaveHeight(0);
 
         // LogStream << m_ulIter << ": on shadow linking line with coast end [" << pPtiCoast->nGetX() << "][" << pPtiCoast->nGetY() << "] = {" << dGridCentroidXToExtCRSX(pPtiCoast->nGetX()) << ", " << dGridCentroidYToExtCRSY(pPtiCoast->nGetY()) << "} and shadow boundary end [" << PtiShadowBoundary.nGetX() << "][" << PtiShadowBoundary.nGetY() << "] = {" << dGridCentroidXToExtCRSX(PtiShadowBoundary.nGetX()) << ", " << dGridCentroidYToExtCRSY(PtiShadowBoundary.nGetY()) << "}, this point [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "}" << endl << "angle subtended = " << dOmega << " degrees, m_pRasterGrid->m_Cell[" << nX << "][" << nY << "].dGetCellDeepWaterWaveHeight() = " << m_pRasterGrid->m_Cell[nX][nY].dGetCellDeepWaterWaveHeight() << " degrees, wave orientation = 0 degrees, wave height = 0 m" << endl;
      }
 
      else
      {
         // Adapted from equation 12 in Hurst et al.
         double const dDeltaShadowWaveAngle = 1.5 * dOmega;
 
         // Get the pre-existing (i.e. shore-parallel) wave orientation
         double const dWaveAngle = m_pRasterGrid->m_Cell[nX][nY].dGetWaveAngle();
 
         double dShadowWaveAngle;
 
         if (nShadowZoneCoastToCapeSeaHand == LEFT_HANDED)
            dShadowWaveAngle = dWaveAngle + dDeltaShadowWaveAngle;
 
         else
            dShadowWaveAngle = dWaveAngle - dDeltaShadowWaveAngle;
 
         // Set the shadow zone wave orientation
         m_pRasterGrid->m_Cell[nX][nY].SetWaveAngle(dKeepWithin360(dShadowWaveAngle));
 
         // Now calculate wave height within the shadow zone, use equation 13 from Hurst et al.
         double const dKp = 0.5 * cos(dOmega * PI / 180);
 
         // Get the pre-existing (i.e. shore-parallel) wave height
         double const dWaveHeight = m_pRasterGrid->m_Cell[nX][nY].dGetWaveHeight();
 
         // Set the shadow zone wave height
         m_pRasterGrid->m_Cell[nX][nY].SetWaveHeight(dKp * dWaveHeight);
 
         // LogStream << m_ulIter << ": on shadow linking line with coast end [" << pPtiCoast->nGetX() << "][" << pPtiCoast->nGetY() << "] = {" << dGridCentroidXToExtCRSX(pPtiCoast->nGetX()) << ", " << dGridCentroidYToExtCRSY(pPtiCoast->nGetY()) << "} and shadow boundary end [" << PtiShadowBoundary.nGetX() << "][" << PtiShadowBoundary.nGetY() << "] = {" << dGridCentroidXToExtCRSX(PtiShadowBoundary.nGetX()) << ", " << dGridCentroidYToExtCRSY(PtiShadowBoundary.nGetY()) << "}, this point [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "}, angle subtended = " << dOmega << " degrees, m_pRasterGrid->m_Cell[" << nX << "][" << nY << "].dGetCellDeepWaterWaveHeight() = " << m_pRasterGrid->m_Cell[nX][nY].dGetCellDeepWaterWaveHeight() << " m, dDeltaShadowWaveAngle = " << dDeltaShadowWaveAngle << " degrees, dWaveAngle = " << dWaveAngle << " degrees, dShadowWaveAngle = " << dShadowWaveAngle << " degrees, dWaveHeight = " << dWaveHeight << " m, dKp = " << dKp << ", shadow zone wave height = " << dKp * dWaveHeight << " m" << endl;
      }
   }
}