EVOLUTION-MANAGER

Edit File: ograssemblepolygon.cpp

/******************************************************************************
 *
 * Project:  S-57 Reader
 * Purpose:  Implements polygon assembly from a bunch of arcs.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 1999, Frank Warmerdam
 * Copyright (c) 2009-2011, Even Rouault <even dot rouault at mines-paris dot org>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ****************************************************************************/

#include "cpl_port.h"
#include "ogr_api.h"

#include <cmath>
#include <cstddef>
#include <list>
#include <vector>

#include "ogr_core.h"
#include "ogr_geometry.h"
#include "cpl_conv.h"
#include "cpl_error.h"

CPL_CVSID("$Id: ograssemblepolygon.cpp f612550694fa03e106256d090786a3199b734636 2019-03-20 20:41:03 +0100 Even Rouault $")

/************************************************************************/
/*                            CheckPoints()                             */
/*                                                                      */
/*      Check if two points are closer than the current best            */
/*      distance.  Update the current best distance if they are.        */
/************************************************************************/

static bool CheckPoints( OGRLineString *poLine1, int iPoint1,
                         OGRLineString *poLine2, int iPoint2,
                         double *pdfDistance )

{
    if( pdfDistance == nullptr || *pdfDistance == 0 )
    {
        if( poLine1->getX(iPoint1) == poLine2->getX(iPoint2)
            && poLine1->getY(iPoint1) == poLine2->getY(iPoint2) )
        {
            if( pdfDistance )
                *pdfDistance = 0.0;
            return true;
        }
        return false;
    }

const double dfDeltaX =
        std::abs(poLine1->getX(iPoint1) - poLine2->getX(iPoint2));

if( dfDeltaX > *pdfDistance )
        return false;

const double dfDeltaY =
        std::abs(poLine1->getY(iPoint1) - poLine2->getY(iPoint2));

if( dfDeltaY > *pdfDistance )
        return false;

const double dfDistance = sqrt(dfDeltaX*dfDeltaX + dfDeltaY*dfDeltaY);

if( dfDistance < *pdfDistance )
    {
        *pdfDistance = dfDistance;
        return true;
    }

return false;
}

/************************************************************************/
/*                           AddEdgeToRing()                            */
/************************************************************************/

static void AddEdgeToRing( OGRLinearRing * poRing, OGRLineString * poLine,
                           bool bReverse, double dfTolerance )

{
/* -------------------------------------------------------------------- */
/*      Establish order and range of traverse.                          */
/* -------------------------------------------------------------------- */
    const int nVertToAdd = poLine->getNumPoints();

int iStart = bReverse ? nVertToAdd - 1 : 0;
    const int iEnd = bReverse ? 0 : nVertToAdd - 1;
    const int iStep = bReverse ? -1 : 1;

/* -------------------------------------------------------------------- */
/*      Should we skip a repeating vertex?                              */
/* -------------------------------------------------------------------- */
    if( poRing->getNumPoints() > 0
        && CheckPoints( poRing, poRing->getNumPoints()-1,
                        poLine, iStart, &dfTolerance ) )
    {
        iStart += iStep;
    }

poRing->addSubLineString( poLine, iStart, iEnd );
}

/************************************************************************/
/*                      OGRBuildPolygonFromEdges()                      */
/************************************************************************/

/**
 * Build a ring from a bunch of arcs.
 *
 * @param hLines handle to an OGRGeometryCollection (or OGRMultiLineString)
 * containing the line string geometries to be built into rings.
 * @param bBestEffort not yet implemented???.
 * @param bAutoClose indicates if the ring should be close when first and
 * last points of the ring are the same.
 * @param dfTolerance tolerance into which two arcs are considered
 * close enough to be joined.
 * @param peErr OGRERR_NONE on success, or OGRERR_FAILURE on failure.
 * @return an handle to the new geometry, a polygon.
 *
 */

OGRGeometryH OGRBuildPolygonFromEdges( OGRGeometryH hLines,
                                       CPL_UNUSED int bBestEffort,
                                       int bAutoClose,
                                       double dfTolerance,
                                       OGRErr * peErr )

{
    if( hLines == nullptr )
    {
        if( peErr != nullptr )
            *peErr = OGRERR_NONE;
        return nullptr;
    }

/* -------------------------------------------------------------------- */
/*      Check for the case of a geometrycollection that can be          */
/*      promoted to MultiLineString.                                    */
/* -------------------------------------------------------------------- */
    OGRGeometry* poGeom = reinterpret_cast<OGRGeometry *>(hLines);
    if( wkbFlatten(poGeom->getGeometryType()) == wkbGeometryCollection )
    {
        for( auto&& poMember: poGeom->toGeometryCollection() )
        {
            if( wkbFlatten(poMember->getGeometryType()) != wkbLineString )
            {
                if( peErr != nullptr )
                    *peErr = OGRERR_FAILURE;
                CPLError(CE_Failure, CPLE_NotSupported,
                         "The geometry collection contains "
                         "non-line string geometries");
                return nullptr;
            }
        }
    }
    else if( wkbFlatten(poGeom->getGeometryType()) != wkbMultiLineString )
    {
        if( peErr != nullptr )
            *peErr = OGRERR_FAILURE;
        CPLError(CE_Failure, CPLE_NotSupported,
                 "The passed geometry is not an OGRGeometryCollection "
                 "(or OGRMultiLineString) "
                 "containing line string geometries");
        return nullptr;
    }

bool bSuccess = true;
    OGRGeometryCollection *poLines = poGeom->toGeometryCollection();
    std::vector<OGRLinearRing*> apoRings;

/* -------------------------------------------------------------------- */
/*      Setup array of line markers indicating if they have been        */
/*      added to a ring yet.                                            */
/* -------------------------------------------------------------------- */
    const int nEdges = poLines->getNumGeometries();
    std::list<OGRLineString*> oListEdges;
    for( int i = 0; i < nEdges; i++ ) 
    {
        OGRLineString *poLine = poLines->getGeometryRef(i)->toLineString();
        if( poLine->getNumPoints() >= 2 )
        {
            oListEdges.push_back(poLine);
        }
    }

/* ==================================================================== */
/*      Loop generating rings.                                          */
/* ==================================================================== */
    while( !oListEdges.empty() )
    {
/* -------------------------------------------------------------------- */
/*      Find the first unconsumed edge.                                 */
/* -------------------------------------------------------------------- */
        OGRLineString *poLine = oListEdges.front();
        oListEdges.erase(oListEdges.begin());

/* -------------------------------------------------------------------- */
/*      Start a new ring, copying in the current line directly          */
/* -------------------------------------------------------------------- */
        OGRLinearRing *poRing = new OGRLinearRing();

AddEdgeToRing( poRing, poLine, FALSE, 0 );

/* ==================================================================== */
/*      Loop adding edges to this ring until we make a whole pass       */
/*      within finding anything to add.                                 */
/* ==================================================================== */
        bool bWorkDone = true;
        double dfBestDist = dfTolerance;

while( !CheckPoints(poRing, 0, poRing, poRing->getNumPoints() - 1, nullptr)
               && !oListEdges.empty()
               && bWorkDone )
        {
            bool bReverse = false;

bWorkDone = false;
            dfBestDist = dfTolerance;

// We consider linking the end to the beginning.  If this is
            // closer than any other option we will just close the loop.

// CheckPoints(poRing, 0, poRing, poRing->getNumPoints()-1,
            //             &dfBestDist);

// Find unused edge with end point closest to our loose end.
            OGRLineString* poBestEdge = nullptr;
            std::list<OGRLineString*>::iterator oBestIter;
            for( auto oIter = oListEdges.begin(); oIter != oListEdges.end(); ++oIter )
            {
                poLine = *oIter;

if( CheckPoints(poLine, 0, poRing, poRing->getNumPoints() - 1,
                                &dfBestDist) )
                {
                    poBestEdge = poLine;
                    oBestIter = oIter;
                    bReverse = false;
                }
                if( CheckPoints(poLine, poLine->getNumPoints() - 1,
                                poRing, poRing->getNumPoints() - 1,
                                &dfBestDist) )
                {
                    poBestEdge = poLine;
                    oBestIter = oIter;
                    bReverse = true;
                }

// If we found an exact match, jump now.
                if( dfBestDist == 0.0 && poBestEdge != nullptr ) break;
            }

// We found one within tolerance - add it.
            if( poBestEdge )
            {
                AddEdgeToRing( poRing, poBestEdge, bReverse, dfTolerance );

oListEdges.erase(oBestIter);
                bWorkDone = true;
            }
        }

/* -------------------------------------------------------------------- */
/*      Did we fail to complete the ring?                               */
/* -------------------------------------------------------------------- */
        dfBestDist = dfTolerance;

if( !CheckPoints(poRing, 0, poRing, poRing->getNumPoints() - 1,
                         &dfBestDist) )
        {
            CPLDebug( "OGR",
                      "Failed to close ring %d.\n"
                      "End Points are: (%.8f,%.7f) and (%.7f,%.7f)",
                      static_cast<int>(apoRings.size()),
                      poRing->getX(0), poRing->getY(0),
                      poRing->getX(poRing->getNumPoints() - 1),
                      poRing->getY(poRing->getNumPoints() - 1) );

bSuccess = false;
        }

/* -------------------------------------------------------------------- */
/*      Do we need to auto-close this ring?                             */
/* -------------------------------------------------------------------- */
        dfBestDist = dfTolerance;

if( bAutoClose )
        {
            if ( !CheckPoints(poRing, 0, poRing, poRing->getNumPoints() - 1,
                              &dfBestDist) )
            {
                poRing->addPoint(poRing->getX(0),
                                 poRing->getY(0),
                                 poRing->getZ(0));
            }
            else if ( !CheckPoints(poRing, 0, poRing,
                                   poRing->getNumPoints() - 1, nullptr) )
            {
                // The endpoints are very close but do not exactly match.
                // Alter the last one so it is equal to the first, to prevent
                // invalid self-intersecting rings.
                poRing->setPoint( poRing->getNumPoints() - 1, poRing->getX(0),
                    poRing->getY(0), poRing->getZ(0) );
            }
        }

apoRings.push_back(poRing);
    }  // Next ring.

/* -------------------------------------------------------------------- */
/*      Identify exterior ring - it will be the largest.  #3610         */
/* -------------------------------------------------------------------- */
    double maxarea = 0.0;
    int maxring = -1;
    OGREnvelope tenv;

for( int rn = 0; rn < static_cast<int>(apoRings.size()); ++rn )
    {
        apoRings[rn]->getEnvelope(&tenv);
        const double tarea = (tenv.MaxX - tenv.MinX) * (tenv.MaxY - tenv.MinY);
        if( tarea > maxarea )
        {
            maxarea = tarea;
            maxring = rn;
        }
    }

OGRPolygon *poPolygon = new OGRPolygon();

if( maxring != -1 )
    {
        poPolygon->addRingDirectly(apoRings[maxring]);
        for( int rn = 0; rn < static_cast<int>(apoRings.size()); ++rn )
        {
            if( rn == maxring ) continue;
            poPolygon->addRingDirectly(apoRings[rn]);
        }
    }
    else
    {
        for( auto& poRing: apoRings )
            delete poRing;
    }

if( peErr != nullptr )
    {
        *peErr = bSuccess ? OGRERR_NONE : OGRERR_FAILURE;
    }

return reinterpret_cast<OGRGeometryH>(poPolygon);
}