LCOV - code coverage report
Current view: directory - ogr - ogrlinearring.cpp (source / functions) Found Hit Coverage
Test: gdal_filtered.info Lines: 198 159 80.3 %
Date: 2012-04-28 Functions: 22 15 68.2 %

       1                 : /******************************************************************************
       2                 :  * $Id: ogrlinearring.cpp 24284 2012-04-21 17:31:57Z rouault $
       3                 :  *
       4                 :  * Project:  OpenGIS Simple Features Reference Implementation
       5                 :  * Purpose:  The OGRLinearRing geometry class.
       6                 :  * Author:   Frank Warmerdam, warmerdam@pobox.com
       7                 :  *
       8                 :  ******************************************************************************
       9                 :  * Copyright (c) 1999, Frank Warmerdam
      10                 :  *
      11                 :  * Permission is hereby granted, free of charge, to any person obtaining a
      12                 :  * copy of this software and associated documentation files (the "Software"),
      13                 :  * to deal in the Software without restriction, including without limitation
      14                 :  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
      15                 :  * and/or sell copies of the Software, and to permit persons to whom the
      16                 :  * Software is furnished to do so, subject to the following conditions:
      17                 :  *
      18                 :  * The above copyright notice and this permission notice shall be included
      19                 :  * in all copies or substantial portions of the Software.
      20                 :  *
      21                 :  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
      22                 :  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
      23                 :  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
      24                 :  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
      25                 :  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
      26                 :  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
      27                 :  * DEALINGS IN THE SOFTWARE.
      28                 :  ****************************************************************************/
      29                 : 
      30                 : #include "ogr_geometry.h"
      31                 : #include "ogr_p.h"
      32                 : 
      33                 : CPL_CVSID("$Id: ogrlinearring.cpp 24284 2012-04-21 17:31:57Z rouault $");
      34                 : 
      35                 : /************************************************************************/
      36                 : /*                           OGRLinearRing()                            */
      37                 : /************************************************************************/
      38                 : 
      39          127881 : OGRLinearRing::OGRLinearRing()
      40                 : 
      41                 : {
      42          127881 : }
      43                 : 
      44                 : /************************************************************************/
      45                 : /*                          ~OGRLinearRing()                            */
      46                 : /************************************************************************/
      47          258051 : OGRLinearRing::~OGRLinearRing()
      48                 : 
      49                 : {
      50          258051 : }
      51                 : 
      52                 : /************************************************************************/
      53                 : /*                           OGRLinearRing()                            */
      54                 : /************************************************************************/
      55                 : 
      56          130170 : OGRLinearRing::OGRLinearRing( OGRLinearRing * poSrcRing )
      57                 : 
      58                 : {
      59          130170 :     if( poSrcRing == NULL )
      60                 :     {
      61               0 :         CPLDebug( "OGR", "OGRLinearRing::OGRLinearRing(OGRLinearRing*poSrcRing) - passed in ring is NULL!" );
      62               0 :         return;
      63                 :     }
      64                 : 
      65          130170 :     setNumPoints( poSrcRing->getNumPoints() );
      66                 : 
      67                 :     memcpy( paoPoints, poSrcRing->paoPoints,
      68          130170 :             sizeof(OGRRawPoint) * getNumPoints() );
      69                 : 
      70          130170 :     if( poSrcRing->padfZ )
      71                 :     {
      72             360 :         Make3D();
      73             360 :         memcpy( padfZ, poSrcRing->padfZ, sizeof(double) * getNumPoints() );
      74                 :     }
      75               0 : }
      76                 : 
      77                 : /************************************************************************/
      78                 : /*                          getGeometryName()                           */
      79                 : /************************************************************************/
      80                 : 
      81            4090 : const char * OGRLinearRing::getGeometryName() const 
      82                 : 
      83                 : {
      84            4090 :     return "LINEARRING";
      85                 : }
      86                 : 
      87                 : /************************************************************************/
      88                 : /*                              WkbSize()                               */
      89                 : /*                                                                      */
      90                 : /*      Disable this method.                                            */
      91                 : /************************************************************************/
      92                 : 
      93               0 : int OGRLinearRing::WkbSize() const
      94                 : 
      95                 : {
      96               0 :     return 0;
      97                 : }
      98                 : 
      99                 : /************************************************************************/
     100                 : /*                           importFromWkb()                            */
     101                 : /*                                                                      */
     102                 : /*      Disable method for this class.                                  */
     103                 : /************************************************************************/
     104                 : 
     105               0 : OGRErr OGRLinearRing::importFromWkb( unsigned char *pabyData, int nSize ) 
     106                 : 
     107                 : {
     108                 :     (void) pabyData;
     109                 :     (void) nSize;
     110                 : 
     111               0 :     return OGRERR_UNSUPPORTED_OPERATION;
     112                 : }
     113                 : 
     114                 : /************************************************************************/
     115                 : /*                            exportToWkb()                             */
     116                 : /*                                                                      */
     117                 : /*      Disable method for this class.                                  */
     118                 : /************************************************************************/
     119                 : 
     120               0 : OGRErr OGRLinearRing::exportToWkb( OGRwkbByteOrder eByteOrder, 
     121                 :                                    unsigned char * pabyData ) const
     122                 : 
     123                 : {
     124                 :     (void) eByteOrder;
     125                 :     (void) pabyData;
     126                 : 
     127               0 :     return OGRERR_UNSUPPORTED_OPERATION;
     128                 : }
     129                 : 
     130                 : /************************************************************************/
     131                 : /*                           _importFromWkb()                           */
     132                 : /*                                                                      */
     133                 : /*      Helper method for OGRPolygon.  NOT A NORMAL importFromWkb()     */
     134                 : /*      method!                                                         */
     135                 : /************************************************************************/
     136                 : 
     137            2208 : OGRErr OGRLinearRing::_importFromWkb( OGRwkbByteOrder eByteOrder, int b3D, 
     138                 :                                       unsigned char * pabyData,
     139                 :                                       int nBytesAvailable ) 
     140                 : 
     141                 : {
     142            2208 :     if( nBytesAvailable < 4 && nBytesAvailable != -1 )
     143               0 :         return OGRERR_NOT_ENOUGH_DATA;
     144                 : 
     145                 : /* -------------------------------------------------------------------- */
     146                 : /*      Get the vertex count.                                           */
     147                 : /* -------------------------------------------------------------------- */
     148                 :     int         nNewNumPoints;
     149                 :     
     150            2208 :     memcpy( &nNewNumPoints, pabyData, 4 );
     151                 :     
     152            2208 :     if( OGR_SWAP( eByteOrder ) )
     153              38 :         nNewNumPoints = CPL_SWAP32(nNewNumPoints);
     154                 : 
     155                 :     /* Check if the wkb stream buffer is big enough to store
     156                 :      * fetched number of points.
     157                 :      * 16 or 24 - size of point structure
     158                 :      */
     159            2208 :     int nPointSize = (b3D ? 24 : 16);
     160            2208 :     if (nNewNumPoints < 0 || nNewNumPoints > INT_MAX / nPointSize)
     161               0 :         return OGRERR_CORRUPT_DATA;
     162            2208 :     int nBufferMinSize = nPointSize * nNewNumPoints;
     163                 :    
     164            2208 :     if( nBytesAvailable != -1 && nBufferMinSize > nBytesAvailable - 4 )
     165                 :     {
     166                 :         CPLError( CE_Failure, CPLE_AppDefined,
     167               0 :                   "Length of input WKB is too small" );
     168               0 :         return OGRERR_NOT_ENOUGH_DATA;
     169                 :     }
     170                 : 
     171                 :     /* (Re)Allocation of paoPoints buffer. */
     172            2208 :     setNumPoints( nNewNumPoints );
     173                 : 
     174            2208 :     if( b3D )
     175             546 :         Make3D();
     176                 :     else
     177            1662 :         Make2D();
     178                 :     
     179                 : /* -------------------------------------------------------------------- */
     180                 : /*      Get the vertices                                                */
     181                 : /* -------------------------------------------------------------------- */
     182            2208 :     int i = 0;
     183                 : 
     184            2208 :     if( !b3D )
     185                 :     {
     186            1662 :         memcpy( paoPoints, pabyData + 4, 16 * nPointCount );
     187                 :     }
     188                 :     else
     189                 :     {
     190           10850 :         for( int i = 0; i < nPointCount; i++ )
     191                 :         {
     192           10304 :             memcpy( &(paoPoints[i].x), pabyData + 4 + 24 * i, 8 );
     193           10304 :             memcpy( &(paoPoints[i].y), pabyData + 4 + 24 * i + 8, 8 );
     194           10304 :             memcpy( padfZ + i, pabyData + 4 + 24 * i + 16, 8 );
     195                 :         }
     196                 :     }
     197                 :     
     198                 : /* -------------------------------------------------------------------- */
     199                 : /*      Byte swap if needed.                                            */
     200                 : /* -------------------------------------------------------------------- */
     201            2208 :     if( OGR_SWAP( eByteOrder ) )
     202                 :     {
     203             196 :         for( i = 0; i < nPointCount; i++ )
     204                 :         {
     205             158 :             CPL_SWAPDOUBLE( &(paoPoints[i].x) );
     206             158 :             CPL_SWAPDOUBLE( &(paoPoints[i].y) );
     207                 : 
     208             158 :             if( b3D )
     209                 :             {
     210              26 :                 CPL_SWAPDOUBLE( padfZ + i );
     211                 :             }
     212                 :         }
     213                 :     }
     214                 : 
     215            2208 :     return OGRERR_NONE;
     216                 : }
     217                 : 
     218                 : /************************************************************************/
     219                 : /*                            _exportToWkb()                            */
     220                 : /*                                                                      */
     221                 : /*      Helper method for OGRPolygon.  THIS IS NOT THE NORMAL           */
     222                 : /*      exportToWkb() METHOD!                                           */
     223                 : /************************************************************************/
     224                 : 
     225            4808 : OGRErr  OGRLinearRing::_exportToWkb( OGRwkbByteOrder eByteOrder, int b3D,
     226                 :                                      unsigned char * pabyData ) const
     227                 : 
     228                 : {
     229                 :     int   i, nWords;
     230                 : 
     231                 : /* -------------------------------------------------------------------- */
     232                 : /*      Copy in the raw data.                                           */
     233                 : /* -------------------------------------------------------------------- */
     234            4808 :     memcpy( pabyData, &nPointCount, 4 );
     235                 : 
     236                 : /* -------------------------------------------------------------------- */
     237                 : /*      Copy in the raw data.                                           */
     238                 : /* -------------------------------------------------------------------- */
     239            4808 :     if( b3D )
     240                 :     {
     241             148 :         nWords = 3 * nPointCount;
     242            3106 :         for( i = 0; i < nPointCount; i++ )
     243                 :         {
     244            2958 :             memcpy( pabyData+4+i*24, &(paoPoints[i].x), 8 );
     245            2958 :             memcpy( pabyData+4+i*24+8, &(paoPoints[i].y), 8 );
     246            2958 :             if( padfZ == NULL )
     247               0 :                 memset( pabyData+4+i*24+16, 0, 8 );
     248                 :             else
     249            2958 :                 memcpy( pabyData+4+i*24+16, padfZ + i, 8 );
     250                 :         }
     251                 :     }
     252                 :     else
     253                 :     {
     254            4660 :         nWords = 2 * nPointCount; 
     255            4660 :         memcpy( pabyData+4, paoPoints, 16 * nPointCount );
     256                 :     }
     257                 : 
     258                 : /* -------------------------------------------------------------------- */
     259                 : /*      Swap if needed.                                                 */
     260                 : /* -------------------------------------------------------------------- */
     261            4808 :     if( OGR_SWAP( eByteOrder ) )
     262                 :     {
     263                 :         int     nCount;
     264                 : 
     265              32 :         nCount = CPL_SWAP32( nPointCount );
     266              32 :         memcpy( pabyData, &nCount, 4 );
     267                 : 
     268             322 :         for( i = 0; i < nWords; i++ )
     269                 :         {
     270             290 :             CPL_SWAPDOUBLE( pabyData + 4 + 8 * i );
     271                 :         }
     272                 :     }
     273                 :     
     274            4808 :     return OGRERR_NONE;
     275                 : }
     276                 : 
     277                 : /************************************************************************/
     278                 : /*                              _WkbSize()                              */
     279                 : /*                                                                      */
     280                 : /*      Helper method for OGRPolygon.  NOT THE NORMAL WkbSize() METHOD! */
     281                 : /************************************************************************/
     282                 : 
     283           14760 : int OGRLinearRing::_WkbSize( int b3D ) const
     284                 : 
     285                 : {
     286           14760 :     if( b3D )
     287            1532 :         return 4 + 24 * nPointCount;
     288                 :     else
     289           13228 :         return 4 + 16 * nPointCount;
     290                 : }
     291                 : 
     292                 : /************************************************************************/
     293                 : /*                               clone()                                */
     294                 : /*                                                                      */
     295                 : /*      We override the OGRCurve clone() to ensure that we get the      */
     296                 : /*      correct virtual table.                                          */
     297                 : /************************************************************************/
     298                 : 
     299             746 : OGRGeometry *OGRLinearRing::clone() const
     300                 : 
     301                 : {
     302                 :     OGRLinearRing       *poNewLinearRing;
     303                 : 
     304             746 :     poNewLinearRing = new OGRLinearRing();
     305             746 :     poNewLinearRing->assignSpatialReference( getSpatialReference() );
     306                 : 
     307             746 :     poNewLinearRing->setPoints( nPointCount, paoPoints, padfZ );
     308                 : 
     309             746 :     return poNewLinearRing;
     310                 : }
     311                 : 
     312                 : 
     313                 : /************************************************************************/
     314                 : /*                            epsilonEqual()                            */
     315                 : /************************************************************************/
     316                 : 
     317                 : static const double EPSILON = 1E-5;
     318                 : 
     319            1788 : static inline bool epsilonEqual(double a, double b, double eps) 
     320                 : {
     321            1788 :     return (::fabs(a - b) < eps);
     322                 : }
     323                 : 
     324                 : /************************************************************************/
     325                 : /*                            isClockwise()                             */
     326                 : /************************************************************************/
     327                 : 
     328                 : /**
     329                 :  * \brief Returns TRUE if the ring has clockwise winding (or less than 2 points)
     330                 :  *
     331                 :  * @return TRUE if clockwise otherwise FALSE.
     332                 :  */
     333                 : 
     334             740 : int OGRLinearRing::isClockwise() const
     335                 : 
     336                 : {
     337                 :     int    i, v, next;
     338                 :     double  dx0, dy0, dx1, dy1, crossproduct;
     339             740 :     int    bUseFallback = FALSE;
     340                 : 
     341             740 :     if( nPointCount < 2 )
     342               0 :         return TRUE;
     343                 : 
     344                 :     /* Find the lowest rightmost vertex */
     345             740 :     v = 0;
     346            8924 :     for ( i = 1; i < nPointCount - 1; i++ )
     347                 :     {
     348                 :         /* => v < end */
     349           22020 :         if ( paoPoints[i].y< paoPoints[v].y ||
     350           13228 :              ( paoPoints[i].y== paoPoints[v].y &&
     351             608 :                paoPoints[i].x > paoPoints[v].x ) )
     352                 :         {
     353            1798 :             v = i;
     354                 :         }
     355                 :     }
     356                 : 
     357                 :     /* previous */
     358             740 :     next = v - 1;
     359             740 :     if ( next < 0 )
     360                 :     {
     361             136 :         next = nPointCount - 1 - 1;
     362                 :     }
     363                 : 
     364            1252 :     if( epsilonEqual(paoPoints[next].x, paoPoints[v].x, EPSILON) &&
     365             512 :         epsilonEqual(paoPoints[next].y, paoPoints[v].y, EPSILON) )
     366                 :     {
     367                 :         /* Don't try to be too clever by retrying with a next point */
     368                 :         /* This can lead to false results as in the case of #3356 */
     369               4 :         bUseFallback = TRUE;
     370                 :     }
     371                 : 
     372             740 :     dx0 = paoPoints[next].x - paoPoints[v].x;
     373             740 :     dy0 = paoPoints[next].y - paoPoints[v].y;
     374                 :     
     375                 :     
     376                 :     /* following */
     377             740 :     next = v + 1;
     378             740 :     if ( next >= nPointCount - 1 )
     379                 :     {
     380             202 :         next = 0;
     381                 :     }
     382                 : 
     383             844 :     if( epsilonEqual(paoPoints[next].x, paoPoints[v].x, EPSILON) &&
     384             104 :         epsilonEqual(paoPoints[next].y, paoPoints[v].y, EPSILON) )
     385                 :     {
     386                 :         /* Don't try to be too clever by retrying with a next point */
     387                 :         /* This can lead to false results as in the case of #3356 */
     388               6 :         bUseFallback = TRUE;
     389                 :     }
     390                 : 
     391             740 :     dx1 = paoPoints[next].x - paoPoints[v].x;
     392             740 :     dy1 = paoPoints[next].y - paoPoints[v].y;
     393                 : 
     394             740 :     crossproduct = dx1 * dy0 - dx0 * dy1;
     395                 : 
     396             740 :     if (!bUseFallback)
     397                 :     {
     398             734 :         if ( crossproduct > 0 )      /* CCW */
     399             152 :             return FALSE;
     400             582 :         else if ( crossproduct < 0 )  /* CW */
     401             582 :             return TRUE;
     402                 :     }
     403                 :     
     404                 :     /* ok, this is a degenerate case : the extent of the polygon is less than EPSILON */
     405                 :     /* or 2 nearly identical points were found */
     406                 :     /* Try with Green Formula as a fallback, but this is not a guarantee */
     407                 :     /* as we'll probably be affected by numerical instabilities */
     408                 :     
     409               6 :     double dfSum = paoPoints[0].x * (paoPoints[1].y - paoPoints[nPointCount-1].y);
     410                 : 
     411            3730 :     for (i=1; i<nPointCount-1; i++) {
     412            3724 :         dfSum += paoPoints[i].x * (paoPoints[i+1].y - paoPoints[i-1].y);
     413                 :     }
     414                 : 
     415               6 :     dfSum += paoPoints[nPointCount-1].x * (paoPoints[0].y - paoPoints[nPointCount-2].y);
     416                 : 
     417               6 :     return dfSum < 0;
     418                 : }
     419                 : 
     420                 : /************************************************************************/ 
     421                 : /*                             reverseWindingOrder()                    */ 
     422                 : /************************************************************************/ 
     423                 : 
     424               0 : void OGRLinearRing::reverseWindingOrder() 
     425                 : 
     426                 : { 
     427               0 :     int pos = 0; 
     428               0 :     OGRPoint tempPoint; 
     429                 : 
     430               0 :     for( int i = 0; i < nPointCount / 2; i++ ) 
     431                 :     { 
     432               0 :         getPoint( i, &tempPoint ); 
     433               0 :         pos = nPointCount - i - 1;
     434               0 :         if( getCoordinateDimension() == 2 )
     435                 :         {
     436               0 :             setPoint( i, getX(pos), getY(pos) );
     437               0 :             setPoint( pos, tempPoint.getX(), tempPoint.getY() );
     438                 :         }
     439                 :         else
     440                 :         {
     441               0 :             setPoint( i, getX(pos), getY(pos), getZ(pos) );
     442               0 :             setPoint( pos, tempPoint.getX(), tempPoint.getY(), tempPoint.getZ() );
     443                 :         }
     444               0 :     } 
     445               0 : } 
     446                 : 
     447                 : /************************************************************************/
     448                 : /*                             closeRing()                              */
     449                 : /************************************************************************/
     450                 : 
     451            1684 : void OGRLinearRing::closeRings()
     452                 : 
     453                 : {
     454            1684 :     if( nPointCount < 2 )
     455               0 :         return;
     456                 : 
     457            1684 :     if( getX(0) != getX(nPointCount-1) 
     458                 :         || getY(0) != getY(nPointCount-1)
     459                 :         || getZ(0) != getZ(nPointCount-1) )
     460                 :     {
     461                 :         /* Avoid implicit change of coordinate dimensionality
     462                 :          * if z=0.0 and dim=2
     463                 :          */
     464             476 :         if( getCoordinateDimension() == 2 )
     465             474 :             addPoint( getX(0), getY(0) );
     466                 :         else
     467               2 :             addPoint( getX(0), getY(0), getZ(0) );
     468                 :             
     469                 :     }
     470                 : }
     471                 : 
     472                 : /************************************************************************/
     473                 : /*                              get_Area()                              */
     474                 : /************************************************************************/
     475                 : 
     476                 : /**
     477                 :  * \brief Compute area of ring.
     478                 :  *
     479                 :  * The area is computed according to Green's Theorem:  
     480                 :  *
     481                 :  * Area is "Sum(x(i)*(y(i+1) - y(i-1)))/2" for i = 0 to pointCount-1, 
     482                 :  * assuming the last point is a duplicate of the first. 
     483                 :  *
     484                 :  * @return computed area.
     485                 :  */
     486                 : 
     487             706 : double OGRLinearRing::get_Area() const
     488                 : 
     489                 : {
     490             706 :     double dfAreaSum = 0.0;
     491                 :     int i;
     492                 : 
     493             706 :     if( nPointCount < 2 )
     494               2 :         return 0;
     495                 : 
     496             704 :     dfAreaSum = paoPoints[0].x * (paoPoints[1].y - paoPoints[nPointCount-1].y);
     497                 : 
     498            9090 :     for( i = 1; i < nPointCount-1; i++ )
     499                 :     {
     500            8386 :         dfAreaSum += paoPoints[i].x * (paoPoints[i+1].y - paoPoints[i-1].y);
     501                 :     }
     502                 : 
     503             704 :     dfAreaSum += paoPoints[nPointCount-1].x * (paoPoints[0].y - paoPoints[nPointCount-2].y);
     504                 : 
     505             704 :     return 0.5 * fabs(dfAreaSum);
     506                 : }
     507                 : 
     508                 : /************************************************************************/
     509                 : /*                              isPointInRing()                         */
     510                 : /************************************************************************/
     511                 : 
     512             520 : OGRBoolean OGRLinearRing::isPointInRing(const OGRPoint* poPoint, int bTestEnvelope) const
     513                 : {
     514             520 :     if ( NULL == poPoint )
     515                 :     {
     516               0 :         CPLDebug( "OGR", "OGRLinearRing::isPointInRing(const  OGRPoint* poPoint) - passed point is NULL!" );
     517               0 :         return 0;
     518                 :     }
     519                 : 
     520             520 :     const int iNumPoints = getNumPoints();
     521                 : 
     522                 :     // Simple validation
     523             520 :     if ( iNumPoints < 4 )
     524               0 :         return 0;
     525                 : 
     526             520 :     const double dfTestX = poPoint->getX();
     527             520 :     const double dfTestY = poPoint->getY();
     528                 : 
     529                 :     // Fast test if point is inside extent of the ring
     530             520 :     if (bTestEnvelope)
     531                 :     {
     532             198 :         OGREnvelope extent;
     533             198 :         getEnvelope(&extent);
     534             198 :         if ( !( dfTestX >= extent.MinX && dfTestX <= extent.MaxX
     535                 :             && dfTestY >= extent.MinY && dfTestY <= extent.MaxY ) )
     536                 :         {
     537               0 :             return 0;
     538                 :         }
     539                 :     }
     540                 : 
     541                 :   // For every point p in ring,
     542                 :     // test if ray starting from given point crosses segment (p - 1, p)
     543             520 :     int iNumCrossings = 0;
     544                 : 
     545          157330 :     for ( int iPoint = 1; iPoint < iNumPoints; iPoint++ ) 
     546                 :     {
     547          156810 :         const int iPointPrev = iPoint - 1;
     548                 : 
     549          156810 :         const double x1 = getX(iPoint) - dfTestX;
     550          156810 :         const double y1 = getY(iPoint) - dfTestY;
     551                 : 
     552          156810 :         const double x2 = getX(iPointPrev) - dfTestX;
     553          156810 :         const double y2 = getY(iPointPrev) - dfTestY;
     554                 : 
     555          156810 :         if( ( ( y1 > 0 ) && ( y2 <= 0 ) ) || ( ( y2 > 0 ) && ( y1 <= 0 ) ) ) 
     556                 :         {
     557                 :             // Check if ray intersects with segment of the ring
     558            1204 :             const double dfIntersection = ( x1 * y2 - x2 * y1 ) / (y2 - y1);
     559            1204 :             if ( 0.0 < dfIntersection )
     560                 :             {
     561                 :                 // Count intersections
     562             646 :                 iNumCrossings++;
     563                 :             }
     564                 :         }
     565                 :     }
     566                 : 
     567                 :     // If iNumCrossings number is even, given point is outside the ring,
     568                 :     // when the crossings number is odd, the point is inside the ring.
     569             520 :     return ( ( iNumCrossings % 2 ) == 1 ? 1 : 0 );
     570                 : }
     571                 : 
     572                 : /************************************************************************/
     573                 : /*                       isPointOnRingBoundary()                        */
     574                 : /************************************************************************/
     575                 : 
     576              14 : OGRBoolean OGRLinearRing::isPointOnRingBoundary(const OGRPoint* poPoint, int bTestEnvelope) const
     577                 : {
     578              14 :     if ( NULL == poPoint )
     579                 :     {
     580               0 :         CPLDebug( "OGR", "OGRLinearRing::isPointOnRingBoundary(const  OGRPoint* poPoint) - passed point is NULL!" );
     581               0 :         return 0;
     582                 :     }
     583                 : 
     584              14 :     const int iNumPoints = getNumPoints();
     585                 : 
     586                 :     // Simple validation
     587              14 :     if ( iNumPoints < 4 )
     588               0 :         return 0;
     589                 : 
     590              14 :     const double dfTestX = poPoint->getX();
     591              14 :     const double dfTestY = poPoint->getY();
     592                 : 
     593                 :     // Fast test if point is inside extent of the ring
     594              14 :     OGREnvelope extent;
     595              14 :     getEnvelope(&extent);
     596              14 :     if ( !( dfTestX >= extent.MinX && dfTestX <= extent.MaxX
     597                 :          && dfTestY >= extent.MinY && dfTestY <= extent.MaxY ) )
     598                 :     {
     599               0 :         return 0;
     600                 :     }
     601                 : 
     602              26 :     for ( int iPoint = 1; iPoint < iNumPoints; iPoint++ ) 
     603                 :     {
     604              26 :         const int iPointPrev = iPoint - 1;
     605                 : 
     606              26 :         const double x1 = getX(iPoint) - dfTestX;
     607              26 :         const double y1 = getY(iPoint) - dfTestY;
     608                 : 
     609              26 :         const double x2 = getX(iPointPrev) - dfTestX;
     610              26 :         const double y2 = getY(iPointPrev) - dfTestY;
     611                 : 
     612                 :         /* If iPoint and iPointPrev are the same, go on */
     613              26 :         if (x1 == x2 && y1 == y2)
     614                 :         {
     615               0 :             continue;
     616                 :         }
     617                 : 
     618                 :         /* If the point is on the segment, return immediatly */
     619                 :         /* FIXME? If the test point is not exactly identical to one of */
     620                 :         /* the vertices of the ring, but somewhere on a segment, there's */
     621                 :         /* little chance that we get 0. So that should be tested against some epsilon */
     622              26 :         if ( x1 * y2 - x2 * y1 == 0 )
     623                 :         {
     624              14 :             return 1;
     625                 :         }
     626                 :     }
     627                 : 
     628               0 :     return 0;
     629                 : }

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