Skip to content
Permalink
Browse files
[pal] Fix logic errors in FeaturePart::isConnected
We only want to consider line parts which touch at most once
as connected -- we don't want lines which curve back round
and touch each other not at end points
  • Loading branch information
nyalldawson committed Apr 30, 2021
1 parent 8cd8214 commit d25b4098c82190bab57f969c410d2c8501c47a5d
Showing with 39 additions and 13 deletions.
  1. +39 −13 src/core/pal/feature.cpp
@@ -2088,21 +2088,47 @@ bool FeaturePart::isConnected( FeaturePart *p2 )
const double x1last = x.back();
const double x2first = p2->x.front();
const double x2last = p2->x.back();
const double y1first = x.front();
const double y1last = x.back();
const double y2first = p2->x.front();
const double y2last = p2->x.back();
const double y1first = y.front();
const double y1last = y.back();
const double y2first = p2->y.front();
const double y2last = p2->y.back();

const bool p2startTouches = ( qgsDoubleNear( x1first, x2first ) && qgsDoubleNear( y1first, y2first ) )
|| ( qgsDoubleNear( x1last, x2first ) && qgsDoubleNear( y1last, y2first ) );

const bool p2endTouches = ( qgsDoubleNear( x1first, x2last ) && qgsDoubleNear( y1first, y2last ) )
|| ( qgsDoubleNear( x1last, x2last ) && qgsDoubleNear( y1last, y2last ) );
// only one endpoint can touch, not both
if ( ( !p2startTouches && !p2endTouches ) || ( p2startTouches && p2endTouches ) )
return false;

if ( qgsDoubleNear( x1first, x2first ) && qgsDoubleNear( y1first, y2first ) )
return true;
else if ( qgsDoubleNear( x1first, x2last ) && qgsDoubleNear( y1first, y2last ) )
return true;
else if ( qgsDoubleNear( x1last, x2first ) && qgsDoubleNear( y1last, y2first ) )
return true;
else if ( qgsDoubleNear( x1last, x2last ) && qgsDoubleNear( y1last, y2last ) )
return true;
// now we know that we have one line endpoint touching only, but there's still a chance
// that the other side of p2 may touch the original line NOT at the other endpoint
// so we need to check that this point doesn't intersect
const double p2otherX = p2startTouches ? x2last : x2first;
const double p2otherY = p2startTouches ? y2last : y2first;

GEOSContextHandle_t geosctxt = QgsGeos::getGEOSHandler();

GEOSCoordSequence *coord = GEOSCoordSeq_create_r( geosctxt, 1, 2 );
#if GEOS_VERSION_MAJOR>3 || GEOS_VERSION_MINOR>=8
GEOSCoordSeq_setXY_r( geosctxt, coord, 0, p2otherX, p2otherY );
#else
GEOSCoordSeq_setX_r( geosctxt, coord, 0, p2otherX );
GEOSCoordSeq_setY_r( geosctxt, coord, 0, p2otherY );
#endif

return false;
geos::unique_ptr p2OtherEnd( GEOSGeom_createPoint_r( geosctxt, coord ) );
try
{
return ( GEOSPreparedIntersects_r( geosctxt, preparedGeom(), p2OtherEnd.get() ) != 1 );
}
catch ( GEOSException &e )
{
qWarning( "GEOS exception: %s", e.what() );
QgsMessageLog::logMessage( QObject::tr( "Exception: %1" ).arg( e.what() ), QObject::tr( "GEOS" ) );
return false;
}
}

bool FeaturePart::mergeWithFeaturePart( FeaturePart *other )

0 comments on commit d25b409

Please sign in to comment.