locate_coast.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 <cfloat>
 
#include <iostream>
using std::cerr;
using std::cout;
using std::endl;
using std::ios;
 
#include <iomanip>
using std::resetiosflags;
using std::setiosflags;
using std::setprecision;
using std::setw;
 
#include <string>
using std::to_string;
 
#include <stack>
using std::stack;
 
#include "cme.h"
#include "i_line.h"
#include "line.h"
#include "simulation.h"
#include "raster_grid.h"
#include "coast.h"
 
//===============================================================================================================================
//===============================================================================================================================
int CSimulation::nLocateSeaAndCoasts(int &nValidCoast)
{
   // Find all connected sea cells
   FindAllSeaCells();
 
   // Find every coastline on the raster grid, mark raster cells, then create the vector coastline
   int nRet = nTraceAllCoasts(nValidCoast);
 
   if (nRet != RTN_OK)
      return nRet;
 
   // Have we created any coasts?
   if (m_VCoast.empty())
   {
      cerr << m_ulIter << ": " << ERR << "no coastline located: this iteration SWL = " << m_dThisIterSWL << ", maximum DEM top surface elevation = " << m_dThisIterTopElevMax << ", minimum DEM top surface elevation = " << m_dThisIterTopElevMin << endl;
      return RTN_ERR_NOCOAST;
   }
 
   return RTN_OK;
}
 
//===============================================================================================================================
//===============================================================================================================================
void CSimulation::FindAllSeaCells(void)
{
   // Go along the list of edge cells
   for (unsigned int n = 0; n < m_VEdgeCell.size(); n++)
   {
      if (m_bOmitSearchNorthEdge && m_VEdgeCellEdge[n] == NORTH)
         continue;
 
      if (m_bOmitSearchSouthEdge && m_VEdgeCellEdge[n] == SOUTH)
         continue;
 
      if (m_bOmitSearchWestEdge && m_VEdgeCellEdge[n] == WEST)
         continue;
 
      if (m_bOmitSearchEastEdge && m_VEdgeCellEdge[n] == EAST)
         continue;
 
      int nX = m_VEdgeCell[n].nGetX();
      int nY = m_VEdgeCell[n].nGetY();
 
      if ((m_pRasterGrid->m_Cell[nX][nY].bIsInundated()) && (bFPIsEqual(m_pRasterGrid->m_Cell[nX][nY].dGetSeaDepth(), 0.0, TOLERANCE)))
         // This edge cell is below SWL and sea depth remains set to zero
         CellByCellFillSea(nX, nY);
   }
}
 
//===============================================================================================================================
//===============================================================================================================================
void CSimulation::CellByCellFillSea(int const nXStart, int const nYStart)
{
   // For safety check
   int nRoundLoopMax = m_nXGridSize * m_nYGridSize;
 
   // Create an empty stack
   stack<CGeom2DIPoint> PtiStack;
 
   // Start at the given edge cell, push this onto the stack
   PtiStack.push(CGeom2DIPoint(nXStart, nYStart));
 
   // Then do the cell-by-cell fill loop until there are no more cell coordinates on the stack
   int nRoundLoop = 0;
 
   while (! PtiStack.empty())
   {
      // Safety check
      if (nRoundLoop++ > nRoundLoopMax)
         break;
 
      CGeom2DIPoint Pti = PtiStack.top();
      PtiStack.pop();
 
      int nX = Pti.nGetX();
      int nY = Pti.nGetY();
 
      while ((nX >= 0) && (! m_pRasterGrid->m_Cell[nX][nY].bBasementElevIsMissingValue()) && (m_pRasterGrid->m_Cell[nX][nY].bIsInundated()))
         nX--;
 
      nX++;
 
      bool bSpanAbove = false;
      bool bSpanBelow = false;
 
      while ((nX < m_nXGridSize) && (! m_pRasterGrid->m_Cell[nX][nY].bBasementElevIsMissingValue()) && (m_pRasterGrid->m_Cell[nX][nY].bIsInundated()) && (bFPIsEqual(m_pRasterGrid->m_Cell[nX][nY].dGetSeaDepth(), 0.0, TOLERANCE)))
      {
         // Set the sea depth for this cell
         m_pRasterGrid->m_Cell[nX][nY].SetSeaDepth();
 
         CRWCellLandform* pLandform = m_pRasterGrid->m_Cell[nX][nY].pGetLandform();
         int nCat = pLandform->nGetLFCategory();
 
         // Have we had sediment input here?
         if ((nCat == LF_CAT_SEDIMENT_INPUT) || (nCat == LF_CAT_SEDIMENT_INPUT_SUBMERGED) || (nCat == LF_CAT_SEDIMENT_INPUT_NOT_SUBMERGED))
         {
            if (m_pRasterGrid->m_Cell[nX][nY].bIsInundated())
            {
               pLandform->SetLFCategory(LF_CAT_SEDIMENT_INPUT_SUBMERGED);
               m_pRasterGrid->m_Cell[nX][nY].SetInContiguousSea();
 
               // Set this sea cell to have deep water (off-shore) wave orientation and height, will change this later for cells closer to the shoreline if we have on-shore waves
               m_pRasterGrid->m_Cell[nX][nY].SetWaveValuesToDeepWaterWaveValues();
            }
 
            else
            {
               pLandform->SetLFCategory(LF_CAT_SEDIMENT_INPUT_NOT_SUBMERGED);
            }
         }
 
         else
         {
            // No sediment input here, just mark as sea
            m_pRasterGrid->m_Cell[nX][nY].SetInContiguousSea();
            pLandform->SetLFCategory(LF_CAT_SEA);
 
            // Set this sea cell to have deep water (off-shore) wave orientation and height, will change this later for cells closer to the shoreline if we have on-shore waves
            m_pRasterGrid->m_Cell[nX][nY].SetWaveValuesToDeepWaterWaveValues();
         }
 
         // Now sort out the x-y extremities of the contiguous sea for the bounding box (used later in wave propagation)
         if (nX < m_nXMinBoundingBox)
            m_nXMinBoundingBox = nX;
 
         if (nX > m_nXMaxBoundingBox)
            m_nXMaxBoundingBox = nX;
 
         if (nY < m_nYMinBoundingBox)
            m_nYMinBoundingBox = nY;
 
         if (nY > m_nYMaxBoundingBox)
            m_nYMaxBoundingBox = nY;
 
         // Update count
         m_ulThisIterNumSeaCells++;
 
         if ((! bSpanAbove) && (nY > 0) && (! m_pRasterGrid->m_Cell[nX][nY - 1].bBasementElevIsMissingValue()) && (m_pRasterGrid->m_Cell[nX][nY - 1].bIsInundated()))
         {
            PtiStack.push(CGeom2DIPoint(nX, nY - 1));
            bSpanAbove = true;
         }
 
         else if (bSpanAbove && (nY > 0) && (! m_pRasterGrid->m_Cell[nX][nY - 1].bBasementElevIsMissingValue()) && (! m_pRasterGrid->m_Cell[nX][nY - 1].bIsInundated()))
         {
            bSpanAbove = false;
         }
 
         if ((! bSpanBelow) && (nY < m_nYGridSize - 1) && (! m_pRasterGrid->m_Cell[nX][nY + 1].bBasementElevIsMissingValue()) && (m_pRasterGrid->m_Cell[nX][nY + 1].bIsInundated()))
         {
            PtiStack.push(CGeom2DIPoint(nX, nY + 1));
            bSpanBelow = true;
         }
 
         else if (bSpanBelow && (nY < m_nYGridSize - 1) && (! m_pRasterGrid->m_Cell[nX][nY + 1].bBasementElevIsMissingValue()) && (! m_pRasterGrid->m_Cell[nX][nY + 1].bIsInundated()))
         {
            bSpanBelow = false;
         }
 
         nX++;
      }
   }
 
   // DEBUG CODE ===========================================================================================================
   string strOutFile = m_strOutPath + "is_contiguous_sea_";
   strOutFile += to_string(m_ulIter);
   strOutFile += ".tif";
 
   GDALDriver* pDriver = GetGDALDriverManager()->GetDriverByName("gtiff");
   GDALDataset* pDataSet = pDriver->Create(strOutFile.c_str(), m_nXGridSize, m_nYGridSize, 1, GDT_Float64, m_papszGDALRasterOptions);
   pDataSet->SetProjection(m_strGDALBasementDEMProjection.c_str());
   pDataSet->SetGeoTransform(m_dGeoTransform);
   double* pdRaster = new double[m_nXGridSize * m_nYGridSize];
   int n = 0;
   for (int nY = 0; nY < m_nYGridSize; nY++)
   {
      for (int nX = 0; nX < m_nXGridSize; nX++)
      {
      pdRaster[n++] = m_pRasterGrid->m_Cell[nX][nY].bIsInContiguousSea();
      }
   }
 
   GDALRasterBand* pBand = pDataSet->GetRasterBand(1);
   pBand->SetNoDataValue(m_dMissingValue);
   int nRet = pBand->RasterIO(GF_Write, 0, 0, m_nXGridSize, m_nYGridSize, pdRaster, m_nXGridSize, m_nYGridSize, GDT_Float64, 0, 0, NULL);
   if (nRet == CE_Failure)
   return;
 
   GDALClose(pDataSet);
   delete[] pdRaster;
   // DEBUG CODE ===========================================================================================================
 
   // // DEBUG CODE ===========================================================================================================
   // string strOutFile = m_strOutPath + "is_inundated_";
   // strOutFile += to_string(m_ulIter);
   // strOutFile += ".tif";
   //
   // GDALDriver* pDriver = GetGDALDriverManager()->GetDriverByName("gtiff");
   // GDALDataset* pDataSet = pDriver->Create(strOutFile.c_str(), m_nXGridSize, m_nYGridSize, 1, GDT_Float64, m_papszGDALRasterOptions);
   // pDataSet->SetProjection(m_strGDALBasementDEMProjection.c_str());
   // pDataSet->SetGeoTransform(m_dGeoTransform);
   // double* pdRaster = new double[m_nXGridSize * m_nYGridSize];
   //
   // pDataSet = pDriver->Create(strOutFile.c_str(), m_nXGridSize, m_nYGridSize, 1, GDT_Float64, m_papszGDALRasterOptions);
   // pDataSet->SetProjection(m_strGDALBasementDEMProjection.c_str());
   // pDataSet->SetGeoTransform(m_dGeoTransform);
   //
   // pdRaster = new double[m_nXGridSize * m_nYGridSize];
   // int n = 0;
   // for (int nY = 0; nY < m_nYGridSize; nY++)
   // {
   //    for (int nX = 0; nX < m_nXGridSize; nX++)
   //    {
   //       pdRaster[n++] = m_pRasterGrid->m_Cell[nX][nY].bIsInundated();
   //    }
   // }
   //
   // GDALRasterBand* pBand = pDataSet->GetRasterBand(1);
   // pBand = pDataSet->GetRasterBand(1);
   // pBand->SetNoDataValue(m_dMissingValue);
   // int nRet = pBand->RasterIO(GF_Write, 0, 0, m_nXGridSize, m_nYGridSize, pdRaster, m_nXGridSize, m_nYGridSize, GDT_Float64, 0, 0, NULL);
   // if (nRet == CE_Failure)
   // return;
   //
   // GDALClose(pDataSet);
   // delete[] pdRaster;
   // // DEBUG CODE ===========================================================================================================
 
   // // DEBUG CODE ===========================================================================================================
   // LogStream << m_ulIter << ": cell-by-cell fill of sea from [" << nXStart << "][" << nYStart << "] = {" << dGridCentroidXToExtCRSX(nXStart) << ", " << dGridCentroidYToExtCRSY(nYStart) << "} with SWL = " << m_dThisIterSWL << ", " << m_ulThisIterNumSeaCells << " of " << m_ulNumCells << " cells now marked as sea (" <<  fixed << setprecision(3) << 100.0 * m_ulThisIterNumSeaCells / m_ulNumCells << " %)" << endl;
 
   // LogStream << " m_nXMinBoundingBox = " << m_nXMinBoundingBox << " m_nXMaxBoundingBox = " << m_nXMaxBoundingBox << " m_nYMinBoundingBox = " << m_nYMinBoundingBox << " m_nYMaxBoundingBox = " << m_nYMaxBoundingBox << endl;
   // // DEBUG CODE ===========================================================================================================
}
 
//===============================================================================================================================
//===============================================================================================================================
int CSimulation::nTraceAllCoasts(int &nValidCoast)
{
   if (m_nLogFileDetail >= LOG_FILE_MIDDLE_DETAIL)
      LogStream << m_ulIter << ": Tracing coast" << endl;
 
   vector<bool> VbPossibleStartCellLHEdge;
   vector<bool> VbTraced;
   vector<int> VnSearchDirection;
   vector<CGeom2DIPoint> V2DIPossibleStartCell;
 
   // Go along the list of edge cells and look for possible coastline start/finish cells
   for (unsigned int n = 0; n < m_VEdgeCell.size() - 1; n++)
   {
      if (m_bOmitSearchNorthEdge && (m_VEdgeCellEdge[n] == NORTH || m_VEdgeCellEdge[n + 1] == NORTH))
         continue;
 
      if (m_bOmitSearchSouthEdge && (m_VEdgeCellEdge[n] == SOUTH || m_VEdgeCellEdge[n + 1] == SOUTH))
         continue;
 
      if (m_bOmitSearchWestEdge && (m_VEdgeCellEdge[n] == WEST || m_VEdgeCellEdge[n + 1] == WEST))
         continue;
 
      if (m_bOmitSearchEastEdge && (m_VEdgeCellEdge[n] == EAST || m_VEdgeCellEdge[n + 1] == EAST))
         continue;
 
      int nXThis = m_VEdgeCell[n].nGetX();
      int nYThis = m_VEdgeCell[n].nGetY();
      int nXNext = m_VEdgeCell[n + 1].nGetX();
      int nYNext = m_VEdgeCell[n + 1].nGetY();
 
      // Get "Is it sea?" information for 'this' and 'next' cells
      bool bThisCellIsSea = m_pRasterGrid->m_Cell[nXThis][nYThis].bIsInContiguousSea();
      bool bNextCellIsSea = m_pRasterGrid->m_Cell[nXNext][nYNext].bIsInContiguousSea();
 
      // Are we at a coast?
      if ((! bThisCellIsSea) && bNextCellIsSea)
      {
         // 'This' cell is just inland, has it already been flagged as a possible start for a coastline (even if this subsequently 'failed' as a coastline)?
         if (! m_pRasterGrid->m_Cell[nXThis][nYThis].bIsPossibleCoastStartCell())
         {
            // It has not, so flag it
            m_pRasterGrid->m_Cell[nXThis][nYThis].SetPossibleCoastStartCell();
 
            if (m_nLogFileDetail >= LOG_FILE_ALL)
               LogStream << m_ulIter << ": Flagging [" << nXThis << "][" << nYThis << "] = {" << dGridCentroidXToExtCRSX(nXThis) << ", " << dGridCentroidYToExtCRSY(nYThis) << "} as possible coast start cell (left_handed edge)" << endl;
 
            // And save it
            V2DIPossibleStartCell.push_back(CGeom2DIPoint(nXThis, nYThis));
            VbPossibleStartCellLHEdge.push_back(true);
            VnSearchDirection.push_back(nGetOppositeDirection(m_VEdgeCellEdge[n]));
            VbTraced.push_back(false);
         }
      }
 
      else if (bThisCellIsSea && (! bNextCellIsSea))
      {
         // The 'next' cell is just inland, has it already been flagged as a possible start for a coastline (even if this subsequently 'failed' as a coastline)?
         if (! m_pRasterGrid->m_Cell[nXNext][nYNext].bIsPossibleCoastStartCell())
         {
            // It has not, so flag it
            m_pRasterGrid->m_Cell[nXNext][nYNext].SetPossibleCoastStartCell();
 
            if (m_nLogFileDetail >= LOG_FILE_ALL)
               LogStream << m_ulIter << ": Flagging [" << nXNext << "][" << nYNext << "] = {" << dGridCentroidXToExtCRSX(nXNext) << ", " << dGridCentroidYToExtCRSY(nYNext) << "} as possible coast start cell (right_handed edge)" << endl;
 
            // And save it
            V2DIPossibleStartCell.push_back(CGeom2DIPoint(nXNext, nYNext));
            VbPossibleStartCellLHEdge.push_back(false);
            VnSearchDirection.push_back(nGetOppositeDirection(m_VEdgeCellEdge[n + 1]));
            VbTraced.push_back(false);
         }
      }
   }
 
   // Any possible coastline start/finish cells found?
   if (V2DIPossibleStartCell.size() == 0)
   {
      LogStream << m_ulIter << ": no coastline start/finish points found after grid edges searched.";
 
      if (m_bOmitSearchNorthEdge || m_bOmitSearchSouthEdge || m_bOmitSearchWestEdge || m_bOmitSearchEastEdge)
      {
         LogStream << " Note that the following grid edges were not searched: " << (m_bOmitSearchNorthEdge ? "N " : "") << (m_bOmitSearchSouthEdge ? "S " : "") << (m_bOmitSearchWestEdge ? "W " : "") << (m_bOmitSearchEastEdge ? "E " : "");
      }
 
      LogStream << endl;
 
      return RTN_ERR_TRACING_COAST;
   }
 
   // Some possible coastline start/finish points were found
   LogStream << m_ulIter << ": " << V2DIPossibleStartCell.size() << " possible coastline start/finish points found" << endl;
 
   // OK, so trace from each of these possible start/finish points
   for (unsigned int n = 0; n < V2DIPossibleStartCell.size(); n++)
   {
      if (! VbTraced[n])
      {
         int nRet = 0;
 
         if (VbPossibleStartCellLHEdge[n])
         {
            nRet = nTraceCoastLine(n, VnSearchDirection[n], LEFT_HANDED, &VbTraced, &V2DIPossibleStartCell);
         }
 
         else
         {
            nRet = nTraceCoastLine(n, VnSearchDirection[n], RIGHT_HANDED, &VbTraced, &V2DIPossibleStartCell);
         }
 
         if (nRet == RTN_OK)
         {
            // We have a valid coastline starting from this possible start cell
            VbTraced[n] = true;
            nValidCoast++;
         }
      }
   }
 
   if (nValidCoast > 0)
      return RTN_OK;
 
   else
   {
      cerr << m_ulIter << ": no valid coasts found, see " << m_strLogFile << " for more information" << endl;
      return RTN_ERR_TRACING_COAST;
   }
}
 
//===============================================================================================================================
//===============================================================================================================================
int CSimulation::nTraceCoastLine(unsigned int const nTraceFromStartCellIndex, int const nStartSearchDirection, int const nHandedness, vector<bool>*pVbTraced, vector<CGeom2DIPoint> const* pV2DIPossibleStartCell)
{
   bool bHitStartCell = false;
   bool bAtCoast = false;
   bool bHasLeftStartEdge = false;
   bool bTooLong = false;
   bool bOffEdge = false;
   bool bRepeating = false;
 
   int nStartX = pV2DIPossibleStartCell->at(nTraceFromStartCellIndex).nGetX();
   int nStartY = pV2DIPossibleStartCell->at(nTraceFromStartCellIndex).nGetY();
   int nX = nStartX;
   int nY = nStartY;
   int nSearchDirection = nStartSearchDirection;
   int nRoundLoop = -1;
   // nThisLen = 0;
   // nLastLen = 0,
   // nPreLastLen = 0;
 
   // Temporary coastline as integer points (grid CRS)
   CGeomILine ILTempGridCRS;
 
   // Mark the start cell as coast and add it to the vector object
   m_pRasterGrid->m_Cell[nStartX][nStartY].SetAsCoastline(true);
   CGeom2DIPoint PtiStart(nStartX, nStartY);
   ILTempGridCRS.Append(&PtiStart);
 
   // Start at this grid-edge point and trace the rest of the coastline using the 'wall follower' rule for maze traversal, trying to keep next to cells flagged as sea
   do
   {
      //       // DEBUG CODE ==============================================================================================================
      // LogStream << "Now at [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "}" << endl;
      // LogStream << "ILTempGridCRS is now:" << endl;
      // for (int n = 0; n < ILTempGridCRS.nGetSize(); n++)
      // LogStream << "[" << ILTempGridCRS[n].nGetX() << "][" << ILTempGridCRS[n].nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILTempGridCRS[n].nGetX()) << ", " << dGridCentroidYToExtCRSY(ILTempGridCRS[n].nGetY()) << "}" << endl;
      // LogStream <<  "=================" << endl;
      //       // DEBUG CODE ==============================================================================================================
 
      // Safety check
      if (++nRoundLoop > m_nCoastMax)
      {
         bTooLong = true;
 
         // LogStream << m_ulIter << ": abandoning coastline tracing from [" << nStartX << "][" << nStartY << "] = {" << dGridCentroidXToExtCRSX(nStartX) << ", " << dGridCentroidYToExtCRSY(nStartY) << "}, exceeded maximum search length (" << m_nCoastMax << ")" << endl;
 
         // for (int n = 0; n < ILTempGridCRS.nGetSize(); n++)
         // LogStream << "[" << ILTempGridCRS[n].nGetX() << "][" << ILTempGridCRS[n].nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILTempGridCRS[n].nGetX()) << ", " << dGridCentroidYToExtCRSY(ILTempGridCRS[n].nGetY()) << "}" << endl;
         // LogStream << endl;
 
         break;
      }
 
      // Another safety check
      if ((nRoundLoop > 10) && (ILTempGridCRS.nGetSize() < 2))
      {
         // We've been 10 times round the loop but the coast is still less than 2 coastline points in length, so we must be repeating
         bRepeating = true;
 
         break;
      }
 
      // OK so far: so have we left the start edge?
      if (! bHasLeftStartEdge)
      {
         // We have not yet left the start edge
         if (((nStartSearchDirection == SOUTH) && (nY > nStartY)) || ((nStartSearchDirection == NORTH) && (nY < nStartY)) ||
               ((nStartSearchDirection == EAST) && (nX > nStartX)) || ((nStartSearchDirection == WEST) && (nX < nStartX)))
            bHasLeftStartEdge = true;
 
         // Flag this cell to ensure that it is not chosen as a coastline start cell later
         m_pRasterGrid->m_Cell[nX][nY].SetPossibleCoastStartCell();
         // LogStream << "Flagging [" << nX << "][" << nY << "] as possible coast start cell NOT YET LEFT EDGE" << endl;
      }
 
      // Leave the loop if the vector coastline has left the start edge, then we find a coast cell which is a possible start cell from which a coastline has not yet been traced
      // if (bHasLeftStartEdge && bAtCoast)
      {
         for (unsigned int nn = 0; nn < pVbTraced->size(); nn++)
         {
            if ((nn != nTraceFromStartCellIndex) && (! pVbTraced->at(nn)))
            {
               // LogStream << "[" << pV2DIPossibleStartCell->at(nn).nGetX() << "][" << pV2DIPossibleStartCell->at(nn).nGetY() << "]" << endl;
 
               if (bAtCoast && (nX == pV2DIPossibleStartCell->at(nn).nGetX()) && (nY == pV2DIPossibleStartCell->at(nn).nGetY()))
               {
                  if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
                     LogStream << m_ulIter << ": Possible coastline found, traced from [" << nStartX << "][" << nStartY << "] and hit another coast start cell at [" << nX << "][" << nY << "]" << endl;
 
                  pVbTraced->at(nn) = true;
                  bHitStartCell = true;
                  break;
               }
            }
         }
 
         // LogStream << endl;
      }
 
      if (bHitStartCell)
         break;
 
      // OK now sort out the next iteration of the search
      int nXSeaward = 0;
      int nYSeaward = 0;
      int nSeawardNewDirection = 0;
      int nXStraightOn = 0;
      int nYStraightOn = 0;
      int nXAntiSeaward = 0;
      int nYAntiSeaward = 0;
      int nAntiSeawardNewDirection = 0;
      int nXGoBack = 0;
      int nYGoBack = 0;
      int nGoBackNewDirection = 0;
 
      CGeom2DIPoint Pti(nX, nY);
 
      // Set up the variables
      switch (nHandedness)
      {
         case RIGHT_HANDED:
 
            // The sea is to the right-hand side of the coast as we traverse it. We are just inland, so we need to keep heading right to find the sea
            switch (nSearchDirection)
            {
               case NORTH:
                  // The sea is towards the RHS (E) of the coast, so first try to go right (to the E)
                  nXSeaward = nX + 1;
                  nYSeaward = nY;
                  nSeawardNewDirection = EAST;
 
                  // If can't do this, try to go straight on (to the N)
                  nXStraightOn = nX;
                  nYStraightOn = nY - 1;
 
                  // If can't do either of these, try to go anti-seaward i.e. towards the LHS (W)
                  nXAntiSeaward = nX - 1;
                  nYAntiSeaward = nY;
                  nAntiSeawardNewDirection = WEST;
 
                  // As a last resort, go back (to the S)
                  nXGoBack = nX;
                  nYGoBack = nY + 1;
                  nGoBackNewDirection = SOUTH;
 
                  break;
 
               case EAST:
                  // The sea is towards the RHS (S) of the coast, so first try to go right (to the S)
                  nXSeaward = nX;
                  nYSeaward = nY + 1;
                  nSeawardNewDirection = SOUTH;
 
                  // If can't do this, try to go straight on (to the E)
                  nXStraightOn = nX + 1;
                  nYStraightOn = nY;
 
                  // If can't do either of these, try to go anti-seaward i.e. towards the LHS (N)
                  nXAntiSeaward = nX;
                  nYAntiSeaward = nY - 1;
                  nAntiSeawardNewDirection = NORTH;
 
                  // As a last resort, go back (to the W)
                  nXGoBack = nX - 1;
                  nYGoBack = nY;
                  nGoBackNewDirection = WEST;
 
                  break;
 
               case SOUTH:
                  // The sea is towards the RHS (W) of the coast, so first try to go right (to the W)
                  nXSeaward = nX - 1;
                  nYSeaward = nY;
                  nSeawardNewDirection = WEST;
 
                  // If can't do this, try to go straight on (to the S)
                  nXStraightOn = nX;
                  nYStraightOn = nY + 1;
 
                  // If can't do either of these, try to go anti-seaward i.e. towards the LHS (E)
                  nXAntiSeaward = nX + 1;
                  nYAntiSeaward = nY;
                  nAntiSeawardNewDirection = EAST;
 
                  // As a last resort, go back (to the N)
                  nXGoBack = nX;
                  nYGoBack = nY - 1;
                  nGoBackNewDirection = NORTH;
 
                  break;
 
               case WEST:
                  // The sea is towards the RHS (N) of the coast, so first try to go right (to the N)
                  nXSeaward = nX;
                  nYSeaward = nY - 1;
                  nSeawardNewDirection = NORTH;
 
                  // If can't do this, try to go straight on (to the W)
                  nXStraightOn = nX - 1;
                  nYStraightOn = nY;
 
                  // If can't do either of these, try to go anti-seaward i.e. towards the LHS (S)
                  nXAntiSeaward = nX;
                  nYAntiSeaward = nY + 1;
                  nAntiSeawardNewDirection = SOUTH;
 
                  // As a last resort, go back (to the E)
                  nXGoBack = nX + 1;
                  nYGoBack = nY;
                  nGoBackNewDirection = EAST;
 
                  break;
            }
 
            break;
 
         case LEFT_HANDED:
 
            // The sea is to the left-hand side of the coast as we traverse it. We are just inland, so we need to keep heading left to find the sea
            switch (nSearchDirection)
            {
               case NORTH:
                  // The sea is towards the LHS (W) of the coast, so first try to go left (to the W)
                  nXSeaward = nX - 1;
                  nYSeaward = nY;
                  nSeawardNewDirection = WEST;
 
                  // If can't do this, try to go straight on (to the N)
                  nXStraightOn = nX;
                  nYStraightOn = nY - 1;
 
                  // If can't do either of these, try to go anti-seaward i.e. towards the RHS (E)
                  nXAntiSeaward = nX + 1;
                  nYAntiSeaward = nY;
                  nAntiSeawardNewDirection = EAST;
 
                  // As a last resort, go back (to the S)
                  nXGoBack = nX;
                  nYGoBack = nY + 1;
                  nGoBackNewDirection = SOUTH;
 
                  break;
 
               case EAST:
                  // The sea is towards the LHS (N) of the coast, so first try to go left (to the N)
                  nXSeaward = nX;
                  nYSeaward = nY - 1;
                  nSeawardNewDirection = NORTH;
 
                  // If can't do this, try to go straight on (to the E)
                  nXStraightOn = nX + 1;
                  nYStraightOn = nY;
 
                  // If can't do either of these, try to go anti-seaward i.e. towards the RHS (S)
                  nXAntiSeaward = nX;
                  nYAntiSeaward = nY + 1;
                  nAntiSeawardNewDirection = SOUTH;
 
                  // As a last resort, go back (to the W)
                  nXGoBack = nX - 1;
                  nYGoBack = nY;
                  nGoBackNewDirection = WEST;
 
                  break;
 
               case SOUTH:
                  // The sea is towards the LHS (E) of the coast, so first try to go left (to the E)
                  nXSeaward = nX + 1;
                  nYSeaward = nY;
                  nSeawardNewDirection = EAST;
 
                  // If can't do this, try to go straight on (to the S)
                  nXStraightOn = nX;
                  nYStraightOn = nY + 1;
 
                  // If can't do either of these, try to go anti-seaward i.e. towards the RHS (W)
                  nXAntiSeaward = nX - 1;
                  nYAntiSeaward = nY;
                  nAntiSeawardNewDirection = WEST;
 
                  // As a last resort, go back (to the N)
                  nXGoBack = nX;
                  nYGoBack = nY - 1;
                  nGoBackNewDirection = NORTH;
 
                  break;
 
               case WEST:
                  // The sea is towards the LHS (S) of the coast, so first try to go left (to the S)
                  nXSeaward = nX;
                  nYSeaward = nY + 1;
                  nSeawardNewDirection = SOUTH;
 
                  // If can't do this, try to go straight on (to the W)
                  nXStraightOn = nX - 1;
                  nYStraightOn = nY;
 
                  // If can't do either of these, try to go anti-seaward i.e. towards the RHS (N)
                  nXAntiSeaward = nX;
                  nYAntiSeaward = nY - 1;
                  nAntiSeawardNewDirection = NORTH;
 
                  // As a last resort, go back (to the E)
                  nXGoBack = nX + 1;
                  nYGoBack = nY;
                  nGoBackNewDirection = EAST;
 
                  break;
            }
 
            break;
      }
 
      // Now do the actual search for this timestep: first try going in the direction of the sea. Is this seaward cell still within the grid?
      if (bIsWithinValidGrid(nXSeaward, nYSeaward))
      {
         // It is, so check if the cell in the seaward direction is a sea cell
         if (m_pRasterGrid->m_Cell[nXSeaward][nYSeaward].bIsInContiguousSea())
         {
            // There is sea in this seaward direction, so we are on the coast
            bAtCoast = true;
 
            // Has the current cell already marked been marked as a coast cell?
            if (! m_pRasterGrid->m_Cell[nX][nY].bIsCoastline())
            {
               // Not already marked, is this an intervention cell with the top above SWL?
               if ((bIsInterventionCell(nX, nY)) && (m_pRasterGrid->m_Cell[nX][nY].dGetInterventionTopElev() >= m_dThisIterSWL))
               {
                  // It is, so mark as coast and add it to the vector object
                  m_pRasterGrid->m_Cell[nX][nY].SetAsCoastline(true);
                  ILTempGridCRS.Append(&Pti);
               }
 
               else if (m_pRasterGrid->m_Cell[nX][nY].dGetSedimentTopElev() >= m_dThisIterSWL)
               {
                  // The sediment top is above SWL so mark as coast and add it to the vector object
                  m_pRasterGrid->m_Cell[nX][nY].SetAsCoastline(true);
                  ILTempGridCRS.Append(&Pti);
               }
            }
         }
 
         else
         {
            // The seaward cell is not a sea cell, so we will move to it next time
            nX = nXSeaward;
            nY = nYSeaward;
 
            // And set a new search direction, to keep turning seaward
            nSearchDirection = nSeawardNewDirection;
            continue;
         }
      }
 
      // OK, we couldn't move seaward (but we may have marked the current cell as coast) so next try to move straight on. Is this straight-ahead cell still within the grid?
      if (bIsWithinValidGrid(nXStraightOn, nYStraightOn))
      {
         // It is, so check if there is sea immediately in front
         if (m_pRasterGrid->m_Cell[nXStraightOn][nYStraightOn].bIsInContiguousSea())
         {
            // Sea is in front, so we are on the coast
            bAtCoast = true;
 
            // Has the current cell already marked been marked as a coast cell?
            if (! m_pRasterGrid->m_Cell[nX][nY].bIsCoastline())
            {
               // Not already marked, is this an intervention cell with the top above SWL?
               if ((bIsInterventionCell(nX, nY)) && (m_pRasterGrid->m_Cell[nX][nY].dGetInterventionTopElev() >= m_dThisIterSWL))
               {
                  // It is, so mark as coast and add it to the vector object
                  m_pRasterGrid->m_Cell[nX][nY].SetAsCoastline(true);
                  ILTempGridCRS.Append(&Pti);
               }
 
               else if (m_pRasterGrid->m_Cell[nX][nY].dGetSedimentTopElev() >= m_dThisIterSWL)
               {
                  // The sediment top is above SWL so mark as coast and add it to the vector object
                  m_pRasterGrid->m_Cell[nX][nY].SetAsCoastline(true);
                  ILTempGridCRS.Append(&Pti);
               }
            }
         }
 
         else
         {
            // The straight-ahead cell is not a sea cell, so we will move to it next time
            nX = nXStraightOn;
            nY = nYStraightOn;
 
            // The search direction remains unchanged
            continue;
         }
      }
 
      // Couldn't move either seaward or straight on (but we may have marked the current cell as coast) so next try to move in the anti-seaward direction. Is this anti-seaward cell still within the grid?
      if (bIsWithinValidGrid(nXAntiSeaward, nYAntiSeaward))
      {
         // It is, so check if there is sea in this anti-seaward cell
         if (m_pRasterGrid->m_Cell[nXAntiSeaward][nYAntiSeaward].bIsInContiguousSea())
         {
            // There is sea on the anti-seaward side, so we are on the coast
            bAtCoast = true;
 
            // Has the current cell already marked been marked as a coast cell?
            if (! m_pRasterGrid->m_Cell[nX][nY].bIsCoastline())
            {
               // Not already marked, is this an intervention cell with the top above SWL?
               if ((bIsInterventionCell(nX, nY)) && (m_pRasterGrid->m_Cell[nX][nY].dGetInterventionTopElev() >= m_dThisIterSWL))
               {
                  // It is, so mark as coast and add it to the vector object
                  m_pRasterGrid->m_Cell[nX][nY].SetAsCoastline(true);
                  ILTempGridCRS.Append(&Pti);
               }
 
               else if (m_pRasterGrid->m_Cell[nX][nY].dGetSedimentTopElev() >= m_dThisIterSWL)
               {
                  // The sediment top is above SWL so mark as coast and add it to the vector object
                  m_pRasterGrid->m_Cell[nX][nY].SetAsCoastline(true);
                  ILTempGridCRS.Append(&Pti);
               }
            }
         }
 
         else
         {
            // The anti-seaward cell is not a sea cell, so we will move to it next time
            nX = nXAntiSeaward;
            nY = nYAntiSeaward;
 
            // And set a new search direction, to keep turning seaward
            nSearchDirection = nAntiSeawardNewDirection;
            continue;
         }
      }
 
      // Could not move to the seaward side, move straight ahead, or move to the anti-seaward side, so we must be in a single-cell dead end! As a last resort, turn round and move back to where we just came from, but first check that this is a valid cell
      if (bIsWithinValidGrid(nXGoBack, nYGoBack))
      {
         nX = nXGoBack;
         nY = nYGoBack;
 
         // And change the search direction
         nSearchDirection = nGoBackNewDirection;
      }
 
      else
      {
         // Our final choice is not a valid cell, so give up
         bOffEdge = true;
         break;
      }
   } while (true);
 
   // OK, we have finished tracing this coastline on the grid. But is the coastline too long or too short?
   int nCoastSize = ILTempGridCRS.nGetSize();
 
   if (bOffEdge)
   {
      if (m_nLogFileDetail >= LOG_FILE_ALL)
         LogStream << m_ulIter << ": Ignoring possible coastline from [" << nStartX << "][" << nStartY << "] = {" << dGridCentroidXToExtCRSX(nStartX) << ", " << dGridCentroidYToExtCRSY(nStartY) << "} since hit off-edge cell at [" << nX << "][" << nY << "] = {" << dGridCentroidXToExtCRSX(nX) << ", " << dGridCentroidYToExtCRSY(nY) << "}, coastline size is " << nCoastSize << endl;
 
      // Unmark these cells as coast cells
      for (int n = 0; n < nCoastSize; n++)
         m_pRasterGrid->m_Cell[ILTempGridCRS[n].nGetX()][ILTempGridCRS[n].nGetY()].SetAsCoastline(false);
 
      return RTN_ERR_TRACING_COAST;
   }
 
   if (bTooLong)
   {
      // Around loop too many times, so abandon this coastline
      if (m_nLogFileDetail >= LOG_FILE_ALL)
      {
         LogStream << m_ulIter << ": Ignoring possible coastline from [" << nStartX << "][" << nStartY << "] = {" << dGridCentroidXToExtCRSX(nStartX) << ", " << dGridCentroidYToExtCRSY(nStartY) << "} since round loop " << nRoundLoop << " times (m_nCoastMax = " << m_nCoastMax << "), coastline size is " << nCoastSize;
 
         if (nCoastSize > 0)
            LogStream << ", it ended at [" << ILTempGridCRS[nCoastSize - 1].nGetX() << "][" << ILTempGridCRS[nCoastSize - 1].nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILTempGridCRS[nCoastSize - 1].nGetX()) << ", " << dGridCentroidYToExtCRSY(ILTempGridCRS[nCoastSize - 1].nGetY()) << "}";
 
         LogStream << endl;
      }
 
      // Unmark these cells as coast cells
      for (int n = 0; n < nCoastSize; n++)
         m_pRasterGrid->m_Cell[ILTempGridCRS[n].nGetX()][ILTempGridCRS[n].nGetY()].SetAsCoastline(false);
 
      return RTN_ERR_TRACING_COAST;
   }
 
   if (bRepeating)
   {
      if (m_nLogFileDetail >= LOG_FILE_ALL)
      {
         LogStream << m_ulIter << ": Ignoring possible coastline from [" << nStartX << "][" << nStartY << "] = {" << dGridCentroidXToExtCRSX(nStartX) << ", " << dGridCentroidYToExtCRSY(nStartY) << "} since repeating, coastline size is " << nCoastSize;
 
         if (nCoastSize > 0)
            LogStream << ", it ended at [" << ILTempGridCRS[nCoastSize - 1].nGetX() << "][" << ILTempGridCRS[nCoastSize - 1].nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILTempGridCRS[nCoastSize - 1].nGetX()) << ", " << dGridCentroidYToExtCRSY(ILTempGridCRS[nCoastSize - 1].nGetY()) << "}";
 
         LogStream << endl;
      }
 
      // Unmark these cells as coast cells
      for (int n = 0; n < nCoastSize; n++)
         m_pRasterGrid->m_Cell[ILTempGridCRS[n].nGetX()][ILTempGridCRS[n].nGetY()].SetAsCoastline(false);
 
      return RTN_ERR_TRACING_COAST;
   }
 
   if (nCoastSize == 0)
   {
      // Zero-length coastline, so abandon it
      if (m_nLogFileDetail >= LOG_FILE_ALL)
         LogStream << m_ulIter << ": abandoning zero-length coastline from [" << nStartX << "][" << nStartY << "] = {" << dGridCentroidXToExtCRSX(nStartX) << ", " << dGridCentroidYToExtCRSY(nStartY) << "}" << endl;
 
      return RTN_ERR_TRACING_COAST;
   }
 
   if (nCoastSize < m_nCoastMin)
   {
      // The vector coastline is too small, so abandon it
      if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
         LogStream << m_ulIter << ": Ignoring possible coastline from [" << nStartX << "][" << nStartY << "] = {" << dGridCentroidXToExtCRSX(nStartX) << ", " << dGridCentroidYToExtCRSY(nStartY) << "} to [" << ILTempGridCRS[nCoastSize - 1].nGetX() << "][" << ILTempGridCRS[nCoastSize - 1].nGetY() << "] = {" << dGridCentroidXToExtCRSX(ILTempGridCRS[nCoastSize - 1].nGetX()) << ", " << dGridCentroidYToExtCRSY(ILTempGridCRS[nCoastSize - 1].nGetY()) << "} since size (" << nCoastSize << ") is less than minimum (" << m_nCoastMin << ")" << endl;
 
      // Unmark these cells as coast cells
      for (int n = 0; n < nCoastSize; n++)
         m_pRasterGrid->m_Cell[ILTempGridCRS[n].nGetX()][ILTempGridCRS[n].nGetY()].SetAsCoastline(false);
 
      return RTN_ERR_TRACING_COAST;
   }
 
   // OK this new coastline is fine
   int nEndX = nX;
   int nEndY = nY;
   int nCoastEndX = ILTempGridCRS[nCoastSize - 1].nGetX();
   int nCoastEndY = ILTempGridCRS[nCoastSize - 1].nGetY();
 
   if ((nCoastEndX != nEndX) || (nCoastEndY != nEndY))
   {
      // The grid-edge cell at nEndX, nEndY is not already at end of ILTempGridCRS. But is the final cell in ILTempGridCRS already at the edge of the grid?
      if (! m_pRasterGrid->m_Cell[nCoastEndX][nCoastEndY].bIsBoundingBoxEdge())
      {
         // The final cell in ILTempGridCRS is not a grid-edge cell, so add the grid-edge cell and mark the cell as coastline
         ILTempGridCRS.Append(nEndX, nEndY);
         nCoastSize++;
 
         m_pRasterGrid->m_Cell[nEndX][nEndY].SetAsCoastline(true);
      }
   }
 
   // Need to specify start edge and end edge for smoothing routines
   int nStartEdge = m_pRasterGrid->m_Cell[nStartX][nStartY].nGetBoundingBoxEdge();
   int nEndEdge = m_pRasterGrid->m_Cell[nEndX][nEndY].nGetBoundingBoxEdge();
 
   // Next, convert the grid coordinates in ILTempGridCRS (integer values stored as doubles) to external CRS coordinates (which will probably be non-integer, again stored as doubles). This is done now, so that smoothing is more effective
   CGeomLine LTempExtCRS;
 
   for (int j = 0; j < nCoastSize; j++)
   {
      LTempExtCRS.Append(dGridCentroidXToExtCRSX(ILTempGridCRS[j].nGetX()), dGridCentroidYToExtCRSY(ILTempGridCRS[j].nGetY()));
   }
 
   // Now do some smoothing of the vector output, if desired
   if (m_nCoastSmooth == SMOOTH_RUNNING_MEAN)
      LTempExtCRS = LSmoothCoastRunningMean(&LTempExtCRS);
 
   else if (m_nCoastSmooth == SMOOTH_SAVITZKY_GOLAY)
      LTempExtCRS = LSmoothCoastSavitzkyGolay(&LTempExtCRS, nStartEdge, nEndEdge);
 
   //    // DEBUG CODE ==================================================================================================
   // LogStream << "==================================" << endl;
   // for (int j = 0; j < nCoastSize; j++)
   // {
   // LogStream << "{" << dGridCentroidXToExtCRSX(ILTempGridCRS[j].nGetX()) << ", " << dGridCentroidYToExtCRSY(ILTempGridCRS[j].nGetY()) << "}" << "\t{" << LTempExtCRS.dGetXAt(j) << ", " << LTempExtCRS.dGetYAt(j) << "}" << endl;
   // }
   // LogStream << "==================================" << endl;
   //    // DEBUG CODE ==================================================================================================
 
   // Create a new coastline object and append to it the vector of coastline objects
   CRWCoast CoastTmp(this);
   m_VCoast.push_back(CoastTmp);
   int nCoast = static_cast<int>(m_VCoast.size()) - 1;
 
   // Set the coastline (Ext CRS)
   m_VCoast[nCoast].SetCoastlineExtCRS(&LTempExtCRS);
 
   // Set the coastline (Grid CRS)
   m_VCoast[nCoast].SetCoastlineGridCRS(&ILTempGridCRS);
 
   // CGeom2DPoint PtLast(DBL_MIN, DBL_MIN);
   // for (int j = 0; j < nCoastSize; j++)
   // {
   //       // Store the smoothed points (in external CRS) in the coast's m_LCoastlineExtCRS object, also append dummy values to the other attribute vectors
   // if (PtLast != &LTempExtCRS[j])        // Avoid duplicate points
   // {
   // m_VCoast[nCoast].AppendPointToCoastlineExtCRS(LTempExtCRS[j].dGetX(), LTempExtCRS[j].dGetY());
   //
   //          // Also store the locations of the corresponding unsmoothed points (in raster grid CRS) in the coast's m_ILCellsMarkedAsCoastline vector
   // m_VCoast[nCoast].AppendCellMarkedAsCoastline(&ILTempGridCRS[j]);
   // }
   //
   // PtLast = LTempExtCRS[j];
   // }
 
   // Set values for the coast's other attributes: set the coast's handedness, and start and end edges
   m_VCoast[nCoast].SetSeaHandedness(nHandedness);
   m_VCoast[nCoast].SetStartEdge(nStartEdge);
   m_VCoast[nCoast].SetEndEdge(nEndEdge);
 
   if (m_nLogFileDetail >= LOG_FILE_HIGH_DETAIL)
   {
      LogStream << m_ulIter << ": Valid coast " << nCoast << " created, from [" << nStartX << "][" << nStartY << "] to [" << nEndX << "][" << nEndY << "] = {" << dGridCentroidXToExtCRSX(nStartX) << ", " << dGridCentroidYToExtCRSY(nStartY) << "} to {" << dGridCentroidXToExtCRSX(nEndX) << ", " << dGridCentroidYToExtCRSY(nEndY) << "} with " << nCoastSize << " points, handedness = " << (nHandedness == LEFT_HANDED ? "left" : "right") << endl;
 
      LogStream << m_ulIter << ": Smoothed coastline " << nCoast << " runs from {" << LTempExtCRS[0].dGetX() << ", " << LTempExtCRS[0].dGetY() << "} to {" << LTempExtCRS[nCoastSize - 1].dGetX() << ", " << LTempExtCRS[nCoastSize - 1].dGetY() << "} i.e. from the ";
 
      if (nStartEdge == NORTH)
         LogStream << "north";
 
      else if (nStartEdge == SOUTH)
         LogStream << "south";
 
      else if (nStartEdge == WEST)
         LogStream << "west";
 
      else if (nStartEdge == EAST)
         LogStream << "east";
 
      LogStream << " edge to the ";
 
      if (nEndEdge == NORTH)
         LogStream << "north";
 
      else if (nEndEdge == SOUTH)
         LogStream << "south";
 
      else if (nEndEdge == WEST)
         LogStream << "west";
 
      else if (nEndEdge == EAST)
         LogStream << "east";
 
      LogStream << " edge" << endl;
   }
 
   // LogStream << "-----------------" << endl;
   // for (int kk = 0; kk < m_VCoast.back().nGetCoastlineSize(); kk++)
   // LogStream << kk << " [" << m_VCoast.back().pPtiGetCellMarkedAsCoastline(kk)->nGetX() << "][" << m_VCoast.back().pPtiGetCellMarkedAsCoastline(kk)->nGetY() << "] = {" << dGridCentroidXToExtCRSX(m_VCoast.back().pPtiGetCellMarkedAsCoastline(kk)->nGetX()) << ", " << dGridCentroidYToExtCRSY(m_VCoast.back().pPtiGetCellMarkedAsCoastline(kk)->nGetY()) << "}" << endl;
   // LogStream << "-----------------" << endl;
 
   // Next calculate the curvature of the vector coastline
   DoCoastCurvature(nCoast, nHandedness);
 
   // Calculate values for the coast's flux orientation vector
   CalcCoastTangents(nCoast);
 
   // And create the vector of pointers to coastline-normal objects
   m_VCoast[nCoast].CreateProfilesAtCoastPoints();
 
   return RTN_OK;
}
 
//===============================================================================================================================
//===============================================================================================================================
int CSimulation::nLocateFloodAndCoasts(void)
{
   // Find all connected sea cells
   FindAllInundatedCells();
 
   // Find every coastline on the raster grid, mark raster cells, then create the vector coastline
   int nRet = nTraceAllFloodCoasts();
 
   if (nRet != RTN_OK)
      return nRet;
 
   // Have we created any coasts?
   switch (m_nLevel)
   {
      case 0: // WAVESETUP + SURGE:
      {
         if (m_VFloodWaveSetupSurge.empty())
         {
            cerr << m_ulIter << ": " << ERR << "no flood coastline located: this iteration SWL = " << m_dThisIterSWL << ", maximum DEM top surface elevation = " << m_dThisIterTopElevMax << ", minimum DEM top surface elevation = " << m_dThisIterTopElevMin << endl;
            return RTN_ERR_NOCOAST;
         }
 
         break;
      }
 
      case 1: // WAVESETUP + SURGE + RUNUP:
      {
         if (m_VFloodWaveSetupSurgeRunup.empty())
         {
            cerr << m_ulIter << ": " << ERR << "no flood coastline located: this iteration SWL = " << m_dThisIterSWL << ", maximum DEM top surface elevation = " << m_dThisIterTopElevMax << ", minimum DEM top surface elevation = " << m_dThisIterTopElevMin << endl;
            return RTN_ERR_NOCOAST;
         }
 
         break;
      }
   }
 
   return RTN_OK;
}
 
//===============================================================================================================================
//===============================================================================================================================
int CSimulation::FindAllInundatedCells(void)
{
   for (int nX = 0; nX < m_nXGridSize; nX++)
   {
      for (int nY = 0; nY < m_nYGridSize; nY++)
      {
         m_pRasterGrid->m_Cell[nX][nY].UnSetCheckFloodCell();
         m_pRasterGrid->m_Cell[nX][nY].UnSetInContiguousFlood();
         m_pRasterGrid->m_Cell[nX][nY].SetAsFloodLine(false);
      }
   }
 
   // Go along the list of edge cells
   for (unsigned int n = 0; n < m_VEdgeCell.size(); n++)
   {
      if (m_bOmitSearchNorthEdge && m_VEdgeCellEdge[n] == NORTH)
         continue;
 
      if (m_bOmitSearchSouthEdge && m_VEdgeCellEdge[n] == SOUTH)
         continue;
 
      if (m_bOmitSearchWestEdge && m_VEdgeCellEdge[n] == WEST)
         continue;
 
      if (m_bOmitSearchEastEdge && m_VEdgeCellEdge[n] == EAST)
         continue;
 
      int nX = m_VEdgeCell[n].nGetX();
      int nY = m_VEdgeCell[n].nGetY();
 
      if ((! m_pRasterGrid->m_Cell[nX][nY].bIsCellFloodCheck()) && (m_pRasterGrid->m_Cell[nX][nY].bIsInundated()))
      {
         // This edge cell is below SWL and sea depth remains set to zero
         FloodFillLand(nX, nY);
      }
   }
 
   return RTN_OK;
}