Issue Joining Polylines

[jmaniaAZNPL]

I have a list of polylines that form a closing boundary. I want to merge all these polylines into one to create a single entity that represents the boundary. I am using AcDbJoinEntityPE to do so but sometimes it does not join all the lines and I know that they are all touching each other.

AcDbPolyline* joinPolylines( std::vector<AcDbPolyline*> segments )
{
	if( segments.size() < 1 )
	{
		return NULL;
	}

	Acad::ErrorStatus errorStatus;
	AcDbPolyline* ret = new AcDbPolyline();
	
	AcDbJoinEntityPE* joinPE = AcDbJoinEntityPE::cast(segments[0]->queryX(AcDbJoinEntityPE::desc())); 
	AcArray<AcDbEntity*> entities;
	AcGeIntArray index;

	if( joinPE == NULL )
	{
		acutPrintf( L"\nERROR: Could not create join class" );
		return NULL;
	}
	
	ret = (AcDbPolyline*)segments[0]->clone();

	for( int i = 1; i < segments.size(); i++ )
	{
		entities.append( segments[i] );
	}

	errorStatus = joinPE->joinEntities( ret, entities, index );
	if( errorStatus != Acad::eOk )
	{
		acutPrintf( L"\nError: Could not join segments %s", acadErrorStatusText( errorStatus ) );
		return NULL;
	}

	return ret;
}

Here are some screen shots that show the function working and failing in the same file. The brown lines are all the lines segments i am joining and the white line is what my function creates.

[jmaniaAZNPL · Accepted solution]

I found the issue. It happens that my group of polylines sometimes have multiple of the same polyline. This causes join to fail.