Fix some gaps in and around airports

- these gaps were caused by a late clipper stage that optomizes the
  resulting polygon after clipping - including removal of nodes
  whose edges have the same slope.  I was unable to disable this
  optomization without breaking clipper - it would just hang.
  So all clipper operations now save the subject nodes before, and
  reinsert after the op.
- cleaned up some debug - genapts is so fast now, that we can just
  print out the summaries.

src/Airports/GenAirports850/airport.cxx

@@ -37,6 +37,15 @@
 string SGLOG_GREEN  = "\033[0;32m";
 string SGLOG_NORMAL = "\033[0m";
 
+static std::string my_ctime(time_t& tt)
+{
+    char buf[256];
+
+    strcpy(buf,ctime(&tt));
+    buf[strlen(buf)-1]='\0';
+    return std::string( buf );
+}
+
 Airport::Airport( int c, char* def)
 {
     int   numParams;
@@ -356,27 +365,31 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
 
     if (features.size())
     {
+        SG_LOG(SG_GENERAL, SG_INFO, "Build " << features.size() << " Linear Feature Polys");
         for ( unsigned int i=0; i<features.size(); i++ )
         {
-            SG_LOG(SG_GENERAL, SG_INFO, "Build Feature Poly " << i + 1 << " of " << features.size() << " : " << features[i]->GetDescription() );
+            SG_LOG(SG_GENERAL, SG_DEBUG, "Build Feature Poly " << i + 1 << " of " << features.size() << " : " << features[i]->GetDescription() );
 
             features[i]->BuildBtg( line_polys, rwy_lights, make_shapefiles );
         }
+
+        log_time = time(0);
+        SG_LOG( SG_GENERAL, SG_ALERT, "Finished building Linear Features for " << icao << " at " << my_ctime(log_time) );
     }
 
     /* Done with the linear features accumulator */
     tgPolygonFreeClipperAccumulator();
 
-    log_time = time(0);
+    /* Initialize a new accumulator for the other objects */
-    SG_LOG( SG_GENERAL, SG_ALERT, "Finished building Linear Features for " << icao << " at " << ctime(&log_time) );
-
-    // Initialize a new accumulator for the other objects
     tgPolygonInitClipperAccumulator();
 
     // Build runways next
+    if (runways.size())
+    {
+        SG_LOG(SG_GENERAL, SG_INFO, "Build " << runways.size() << " Runway Polys");
         for ( unsigned int i=0; i<runways.size(); i++ )
         {
-        SG_LOG(SG_GENERAL, SG_INFO, "Build Runway " << i + 1 << " of " << runways.size());
+            SG_LOG(SG_GENERAL, SG_DEBUG, "Build Runway " << i + 1 << " of " << runways.size());
             slivers.clear();
 
             if ( isDebugRunway(i) ) {
@@ -400,13 +413,15 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
         }
 
         log_time = time(0);
-    SG_LOG( SG_GENERAL, SG_ALERT, "Finished building runways for " << icao << " at " << ctime(&log_time) );
+        SG_LOG( SG_GENERAL, SG_ALERT, "Finished building runways for " << icao << " at " << my_ctime(log_time) );
+    }
 
     if (lightobjects.size())
     {
+        SG_LOG(SG_GENERAL, SG_INFO, "Build " << lightobjects.size() << " Light Objects ");
         for ( unsigned int i=0; i<lightobjects.size(); i++ )
         {
-            SG_LOG(SG_GENERAL, SG_INFO, "Build runway light " << i + 1 << " of " << lightobjects.size());
+            SG_LOG(SG_GENERAL, SG_DEBUG, "Build runway light " << i + 1 << " of " << lightobjects.size());
             lightobjects[i]->BuildBtg( rwy_lights );
         }
     }
@@ -414,9 +429,10 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
     // Build helipads (use runway poly- and texture list for this)
     if (helipads.size())
     {
+        SG_LOG(SG_GENERAL, SG_INFO, "Build " << helipads.size() << " Helipad Polys ");
         for ( unsigned int i=0; i<helipads.size(); i++ )
         {
-            SG_LOG(SG_GENERAL, SG_INFO, "Build helipad " << i + 1 << " of " << helipads.size());
+            SG_LOG(SG_GENERAL, SG_DEBUG, "Build helipad " << i + 1 << " of " << helipads.size());
             slivers.clear();
 
             if (boundary.size())
@@ -436,9 +452,10 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
     // Build the pavements
     if (pavements.size())
     {
+        SG_LOG(SG_GENERAL, SG_INFO, "Build " << pavements.size() << " Pavement Polys ");
         for ( unsigned int i=0; i<pavements.size(); i++ )
         {
-            SG_LOG(SG_GENERAL, SG_INFO, "Build Pavement " << i + 1 << " of " << pavements.size() << " : " << pavements[i]->GetDescription());
+            SG_LOG(SG_GENERAL, SG_DEBUG, "Build Pavement " << i + 1 << " of " << pavements.size() << " : " << pavements[i]->GetDescription());
             slivers.clear();
 
             if ( isDebugPavement(i) ) {
@@ -461,17 +478,18 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
             tgPolygon::MergeSlivers( rwy_polys, slivers );
             tgPolygon::MergeSlivers( pvmt_polys, slivers );
         }
-    }
 
         log_time = time(0);
-    SG_LOG( SG_GENERAL, SG_ALERT, "Finished building Pavements for " << icao << " at " << ctime(&log_time) );
+        SG_LOG( SG_GENERAL, SG_ALERT, "Finished building Pavements for " << icao << " at " << my_ctime(log_time) );
+    }
 
     // Build the legacy taxiways
     if (taxiways.size())
     {
+        SG_LOG(SG_GENERAL, SG_INFO, "Build " << taxiways.size() << " Taxiway Polys ");
         for ( unsigned int i=0; i<taxiways.size(); i++ )
         {
-            SG_LOG(SG_GENERAL, SG_INFO, "Build Taxiway " << i + 1 << " of " << taxiways.size());
+            SG_LOG(SG_GENERAL, SG_DEBUG, "Build Taxiway " << i + 1 << " of " << taxiways.size());
             slivers.clear();
 
             if ( isDebugTaxiway(i) ) {
@@ -497,9 +515,12 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
     }
 
     // Build runway shoulders here
+    if ( runways.size() )
+    {
+        SG_LOG(SG_GENERAL, SG_INFO, "Build " << runways.size() << " Runway Shoulder Polys ");
         for ( unsigned int i=0; i<runways.size(); i++ )
         {
-        SG_LOG(SG_GENERAL, SG_INFO, "Build Runway shoulder " << i + 1 << " of " << runways.size());
+            SG_LOG(SG_GENERAL, SG_DEBUG, "Build Runway shoulder " << i + 1 << " of " << runways.size());
 
             if ( runways[i]->GetsShoulder() )
             {
@@ -519,11 +540,15 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
                 tgPolygon::MergeSlivers( pvmt_polys, slivers );
             }
         }
+    }
 
     // Build helipad shoulders here
+    if ( helipads.size() )
+    {
+        SG_LOG(SG_GENERAL, SG_INFO, "Build " << runways.size() << " Helipad Shoulder Polys ");
         for ( unsigned int i=0; i<helipads.size(); i++ )
         {
-        SG_LOG(SG_GENERAL, SG_INFO, "Build Helipad shoulder " << i + 1 << " of " << helipads.size());
+            SG_LOG(SG_GENERAL, SG_DEBUG, "Build Helipad shoulder " << i + 1 << " of " << helipads.size());
 
             if ( helipads[i]->GetsShoulder() )
             {
@@ -543,15 +568,17 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
                 tgPolygon::MergeSlivers( pvmt_polys, slivers );
             }
         }
+    }
 
     // build the base and clearing if there's a boundary
     if (boundary.size())
     {
+        SG_LOG(SG_GENERAL, SG_INFO, "Build " << boundary.size() << " Boundary Polys ");
         shapefile = "";
 
         for ( unsigned int i=0; i<boundary.size(); i++ )
         {
-            SG_LOG(SG_GENERAL, SG_INFO, "Build Userdefined boundary " << i + 1 << " of " << boundary.size());
+            SG_LOG(SG_GENERAL, SG_DEBUG, "Build Userdefined boundary " << i + 1 << " of " << boundary.size());
             boundary[i]->BuildBtg( apt_base, apt_clearing, shapefile );
         }
     }
@@ -578,7 +605,6 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
 
     // build temporary node list from runways...
     SG_LOG(SG_GENERAL, SG_INFO, "Build Node List " );
-
     for ( unsigned int k = 0; k < rwy_polys.size(); ++k ) 
     {
     	tgPolygon poly = rwy_polys[k];
@@ -637,7 +663,7 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
     }
 
     log_time = time(0);
-    SG_LOG( SG_GENERAL, SG_ALERT, "Finished collecting nodes for " << icao << " at " << ctime(&log_time) );
+    SG_LOG( SG_GENERAL, SG_ALERT, "Finished collecting nodes for " << icao << " at " << my_ctime(log_time) );
 
     // second pass : runways
     for ( unsigned int k = 0; k < rwy_polys.size(); ++k ) 
@@ -667,7 +693,7 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
     }
 
     log_time = time(0);
-    SG_LOG( SG_GENERAL, SG_ALERT, "Finished adding intermediate nodes for " << icao << " at " << ctime(&log_time) );
+    SG_LOG( SG_GENERAL, SG_ALERT, "Finished adding intermediate nodes for " << icao << " at " << my_ctime(log_time) );
 
     for ( unsigned int k = 0; k < line_polys.size(); ++k )
     {
@@ -687,16 +713,10 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
     }
 
     log_time = time(0);
-    SG_LOG( SG_GENERAL, SG_ALERT, "Finished cleaning polys for " << icao << " at " << ctime(&log_time) );
+    SG_LOG( SG_GENERAL, SG_ALERT, "Finished cleaning polys for " << icao << " at " << my_ctime(log_time) );
-
-    SG_LOG(SG_GENERAL, SG_DEBUG, "add nodes base ");
-    SG_LOG(SG_GENERAL, SG_DEBUG, " before: " << base_poly);
-    SG_LOG(SG_GENERAL, SG_DEBUG, " tmp_pvmt_nodes size = " << tmp_pvmt_nodes.get_node_list().size());
-    SG_LOG(SG_GENERAL, SG_DEBUG, " tmp_feat_nodes size = " << tmp_feat_nodes.get_node_list().size());
 
     base_poly = tgPolygon::AddColinearNodes( base_poly, tmp_pvmt_nodes );
     base_poly = tgPolygon::Snap( base_poly, gSnap );
-    SG_LOG(SG_GENERAL, SG_DEBUG, " after adding tmp_nodes: " << base_poly);
 
     // Finally find slivers in base
     slivers.clear();
@@ -728,37 +748,49 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
     triangulation_start.stamp();
 
     // tesselate the polygons and prepair them for final output
+    if ( rwy_polys.size() )
+    {
+        SG_LOG(SG_GENERAL, SG_INFO, "Tesselating " << rwy_polys.size() << " Runway Polys " );
         for ( unsigned int i = 0; i < rwy_polys.size(); ++i )
         {
-        SG_LOG(SG_GENERAL, SG_INFO, "Tesselating runway poly = " << i + 1 << " of " << rwy_polys.size() );
+            SG_LOG(SG_GENERAL, SG_DEBUG, "Tesselating runway poly = " << i + 1 << " of " << rwy_polys.size() );
 
             SG_LOG(SG_GENERAL, SG_DEBUG, "contours before " << rwy_polys[i].Contours() << " total points before = " << rwy_polys[i].TotalNodes());
             rwy_polys[i].Tesselate();
             SG_LOG(SG_GENERAL, SG_DEBUG, "triangles after = " << rwy_polys[i].Triangles());
             rwy_polys[i].Texture();
         }
+    }
 
+    if ( pvmt_polys.size() )
+    {
         // tesselate the polygons and prepair them for final output
+        SG_LOG(SG_GENERAL, SG_INFO, "Tesselating " << pvmt_polys.size() << " Pavement Polys " );
         for ( unsigned int i = 0; i < pvmt_polys.size(); ++i )
         {
-        SG_LOG(SG_GENERAL, SG_INFO, "Tesselating pavement poly = " << i + 1 << " of " << pvmt_polys.size() );
+            SG_LOG(SG_GENERAL, SG_DEBUG, "Tesselating pavement poly = " << i + 1 << " of " << pvmt_polys.size() );
 
             SG_LOG(SG_GENERAL, SG_DEBUG, "contours before " << pvmt_polys[i].Contours() << " total points before = " << pvmt_polys[i].TotalNodes());
             pvmt_polys[i].Tesselate();
             SG_LOG(SG_GENERAL, SG_DEBUG, "triangles after = " << pvmt_polys[i].Triangles());
             pvmt_polys[i].Texture();
         }
+    }
 
+    if ( line_polys.size() )
+    {
         // tesselate the polygons and prepair them for final output
+        SG_LOG(SG_GENERAL, SG_INFO, "Tesselating " << line_polys.size() << " Linear Feature Polys " );
         for ( unsigned int i = 0; i < line_polys.size(); ++i )
         {
-        SG_LOG(SG_GENERAL, SG_INFO, "Tesselating line poly = " << i + 1 << " of " << line_polys.size() );
+            SG_LOG(SG_GENERAL, SG_DEBUG, "Tesselating line poly = " << i + 1 << " of " << line_polys.size() );
 
             SG_LOG(SG_GENERAL, SG_DEBUG, "contours before " << line_polys[i].Contours() << " total points before = " << line_polys[i].TotalNodes());
             line_polys[i].Tesselate();
             SG_LOG(SG_GENERAL, SG_DEBUG, "triangles after = " << line_polys[i].Triangles());
             line_polys[i].Texture();
         }
+    }
 
     /* before tessellating the base, make sure there are no
        intersecting contours */
@@ -812,7 +844,6 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
     SGVec3d vnt = SGVec3d::fromGeod( base_poly.GetNode(0, 0) );
     vnt = normalize(vnt);
     Point3D vn = Point3D::fromSGVec3(vnt);
-    SG_LOG(SG_GENERAL, SG_DEBUG, "found normal for this airport = " << vn);
 
     SG_LOG(SG_GENERAL, SG_INFO, "Adding runway nodes and normals");
     for ( unsigned int k = 0; k < rwy_polys.size(); ++k ) 
@@ -1065,7 +1096,7 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
     max_deg.setLongitudeDeg( max_deg.getLongitudeDeg() + 0.01 * dlon );
     min_deg.setLatitudeDeg( min_deg.getLatitudeDeg() - 0.01 * dlat );
     max_deg.setLatitudeDeg( max_deg.getLatitudeDeg() + 0.01 * dlat );
-    SG_LOG(SG_GENERAL, SG_INFO, "min = " << min_deg << " max = " << max_deg );
+    SG_LOG(SG_GENERAL, SG_DEBUG, "min = " << min_deg << " max = " << max_deg );
 
     SG_LOG(SG_GENERAL, SG_DEBUG, "Create Apt surface:" );
     SG_LOG(SG_GENERAL, SG_DEBUG, " root: " << root );
@@ -1428,6 +1459,7 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
     }
 
     string holepath = root + "/AirportArea";
+
     tgPolygon::Chop( divided_base, holepath, "Hole", false, true );
     tgPolygon::Chop( apt_clearing, holepath, "Airport", false, false );
 

src/Airports/GenAirports850/closedpoly.cxx

@@ -444,8 +444,6 @@ int ClosedPoly::BuildBtg( tgpolygon_list& rwy_polys, tgcontour_list& slivers, st
 {
     if ( is_pavement && pre_tess.Contours() )
     {
-        SG_LOG(SG_GENERAL, SG_INFO, "BuildBtg: original poly has " << pre_tess.Contours() << " contours" << " and " << pre_tess.TotalNodes() << " points : shapefile_name is " << shapefile_name );
-
         if(  shapefile_name.size() ) {
             tgPolygon::ToShapefile( pre_tess, "./airport_dbg", std::string("preclip"), shapefile_name );
             tgPolygon::AccumulatorToShapefiles( "./airport_dbg", "accum" );
@@ -484,8 +482,6 @@ int ClosedPoly::BuildBtg( tgPolygon& apt_base, tgPolygon& apt_clearing, std::str
     // verify the poly has been generated, and the contour isn't a pavement
     if ( !is_pavement && pre_tess.Contours() )
     {
-        SG_LOG(SG_GENERAL, SG_DEBUG, "BuildBtg: original poly has " << pre_tess.Contours() << " contours");
-
         base = tgPolygon::Expand( pre_tess, 2.0); 
         safe_base = tgPolygon::Expand( pre_tess, 5.0);        
 

src/Airports/GenAirports850/scheduler.cxx

@@ -810,7 +810,7 @@ long Scheduler::FindAirport( string icao )
 
 void Scheduler::RetryAirport( AirportInfo* pai )
 {
-    // retryList.push_back( *pai );        
+    retryList.push_back( *pai );
 }
 
 bool Scheduler::AddAirports( long start_pos, tg::Rectangle* boundingBox )

src/Lib/Polygon/polygon.cxx

@@ -1711,6 +1711,12 @@ tg::Rectangle tgContour::GetBoundingBox( void ) const
 tgPolygon tgContour::DiffWithAccumulator( const tgContour& subject )
 {
     tgPolygon result;
+    TGTriNodes all_nodes;
+
+    /* before diff - gather all nodes */
+    for ( unsigned int i = 0; i < subject.GetSize(); ++i ) {
+        all_nodes.unique_add( Point3D::fromSGGeod( subject.GetNode(i) ));
+    }
 
     unsigned int  num_hits = 0;
     tg::Rectangle box1 = subject.GetBoundingBox();
@@ -1740,6 +1746,7 @@ tgPolygon tgContour::DiffWithAccumulator( const tgContour& subject )
             exit(-1);
         }
         result = tgPolygon::FromClipper( clipper_result );
+        result = tgPolygon::AddColinearNodes( result, all_nodes );
     } else {
         result.AddContour( subject );
     }
@@ -1759,6 +1766,12 @@ void tgContour::AddToAccumulator( const tgContour& subject )
 tgPolygon tgPolygon::Union( const tgContour& subject, tgPolygon& clip )
 {
     tgPolygon result;
+    TGTriNodes all_nodes;
+
+    /* before diff - gather all nodes */
+    for ( unsigned int i = 0; i < subject.GetSize(); ++i ) {
+        all_nodes.unique_add( Point3D::fromSGGeod( subject.GetNode(i) ));
+    }
 
     ClipperLib::Polygon  clipper_subject = tgContour::ToClipper( subject );
     ClipperLib::Polygons clipper_clip    = tgPolygon::ToClipper( clip );
@@ -1770,7 +1783,10 @@ tgPolygon tgPolygon::Union( const tgContour& subject, tgPolygon& clip )
     c.AddPolygons(clipper_clip, ClipperLib::ptClip);
     c.Execute(ClipperLib::ctUnion, clipper_result, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd);
 
-    return tgPolygon::FromClipper( clipper_result );
+    result = tgPolygon::FromClipper( clipper_result );
+    result = tgPolygon::AddColinearNodes( result, all_nodes );
+
+    return result;
 }
 
 tgContour tgContour::AddColinearNodes( const tgContour& subject, TGTriNodes nodes )
@@ -1912,6 +1928,14 @@ tgPolygon tgPolygon::SplitLongEdges( const tgPolygon& subject, double dist )
 tgPolygon tgPolygon::StripHoles( const tgPolygon& subject )
 {
     tgPolygon result;
+    TGTriNodes all_nodes;
+
+    /* before diff - gather all nodes */
+    for ( unsigned int i = 0; i < subject.Contours(); ++i ) {
+        for ( unsigned int j = 0; j < subject.ContourSize( i ); ++j ) {
+            all_nodes.unique_add( Point3D::fromSGGeod( subject.GetNode(i, j) ) );
+        }
+    }
 
     ClipperLib::Polygons clipper_result;
     ClipperLib::Clipper c;
@@ -1926,6 +1950,8 @@ tgPolygon tgPolygon::StripHoles( const tgPolygon& subject )
     c.Execute(ClipperLib::ctUnion, clipper_result, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd);
 
     result = tgPolygon::FromClipper( clipper_result );
+    result = tgPolygon::AddColinearNodes( result, all_nodes );
+
     result.SetMaterial( subject.GetMaterial() );
     result.SetTexParams( subject.GetTexParams() );
 
@@ -1935,11 +1961,21 @@ tgPolygon tgPolygon::StripHoles( const tgPolygon& subject )
 tgPolygon tgPolygon::Simplify( const tgPolygon& subject )
 {
     tgPolygon result;
+    TGTriNodes all_nodes;
+
+    /* before diff - gather all nodes */
+    for ( unsigned int i = 0; i < subject.Contours(); ++i ) {
+        for ( unsigned int j = 0; j < subject.ContourSize( i ); ++j ) {
+            all_nodes.unique_add( Point3D::fromSGGeod( subject.GetNode(i, j) ) );
+        }
+    }
 
     ClipperLib::Polygons clipper_poly = tgPolygon::ToClipper( subject );
     SimplifyPolygons( clipper_poly );
 
     result = tgPolygon::FromClipper( clipper_poly );
+    result = tgPolygon::AddColinearNodes( result, all_nodes );
+
     result.SetMaterial( subject.GetMaterial() );
     result.SetTexParams( subject.GetTexParams() );
 
@@ -2007,6 +2043,12 @@ tgPolygon tgPolygon::FromClipper( const ClipperLib::Polygons& subject )
     return result;
 }
 
+bool clipper_dump = false;
+void tgPolygon::SetDump( bool dmp )
+{
+    clipper_dump = dmp;
+}
+
 tgPolygon tgPolygon::Expand( const tgPolygon& subject, double offset )
 {
     ClipperLib::Polygons clipper_src, clipper_dst;
@@ -2027,23 +2069,59 @@ tgPolygon tgPolygon::Expand( const tgPolygon& subject, double offset )
 tgPolygon tgPolygon::Union( const tgPolygon& subject, tgPolygon& clip )
 {
     tgPolygon     result;
+    TGTriNodes    all_nodes;
+    std::ofstream dmpfile;
+
+    /* before union - gather all nodes */
+    for ( unsigned int i = 0; i < subject.Contours(); ++i ) {
+        for ( unsigned int j = 0; j < subject.ContourSize( i ); ++j ) {
+            all_nodes.unique_add( Point3D::fromSGGeod( subject.GetNode(i, j) ) );
+        }
+    }
 
     ClipperLib::Polygons clipper_subject = tgPolygon::ToClipper( subject );
     ClipperLib::Polygons clipper_clip    = tgPolygon::ToClipper( clip );
     ClipperLib::Polygons clipper_result;
 
+    if ( clipper_dump ) {
+        dmpfile.open ("subject.txt");
+        dmpfile << clipper_subject;
+        dmpfile.close();
+
+        dmpfile.open ("clip.txt");
+        dmpfile << clipper_clip;
+        dmpfile.close();
+    }
+
     ClipperLib::Clipper c;
     c.Clear();
     c.AddPolygons(clipper_subject, ClipperLib::ptSubject);
     c.AddPolygons(clipper_clip, ClipperLib::ptClip);
     c.Execute(ClipperLib::ctUnion, clipper_result, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd);
 
-    return tgPolygon::FromClipper( clipper_result );
+    if ( clipper_dump ) {
+        dmpfile.open ("result.txt");
+        dmpfile << clipper_result;
+        dmpfile.close();
+    }
+
+    result = tgPolygon::FromClipper( clipper_result );
+    result = tgPolygon::AddColinearNodes( result, all_nodes );
+
+    return result;
 }
 
 tgPolygon tgPolygon::Diff( const tgPolygon& subject, tgPolygon& clip )
 {
     tgPolygon result;
+    TGTriNodes all_nodes;
+
+    /* before diff - gather all nodes */
+    for ( unsigned int i = 0; i < subject.Contours(); ++i ) {
+        for ( unsigned int j = 0; j < subject.ContourSize( i ); ++j ) {
+            all_nodes.unique_add( Point3D::fromSGGeod( subject.GetNode(i, j) ) );
+        }
+    }
 
     ClipperLib::Polygons clipper_subject = tgPolygon::ToClipper( subject );
     ClipperLib::Polygons clipper_clip    = tgPolygon::ToClipper( clip );
@@ -2055,12 +2133,23 @@ tgPolygon tgPolygon::Diff( const tgPolygon& subject, tgPolygon& clip )
     c.AddPolygons(clipper_clip, ClipperLib::ptClip);
     c.Execute(ClipperLib::ctDifference, clipper_result, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd);
 
-    return tgPolygon::FromClipper( clipper_result );
+    result = tgPolygon::FromClipper( clipper_result );
+    result = tgPolygon::AddColinearNodes( result, all_nodes );
+
+    return result;
 }
 
 tgPolygon tgPolygon::Intersect( const tgPolygon& subject, const tgPolygon& clip )
 {
     tgPolygon result;
+    TGTriNodes all_nodes;
+
+    /* before intersect - gather all nodes */
+    for ( unsigned int i = 0; i < subject.Contours(); ++i ) {
+        for ( unsigned int j = 0; j < subject.ContourSize( i ); ++j ) {
+            all_nodes.unique_add( Point3D::fromSGGeod( subject.GetNode(i, j) ) );
+        }
+    }
 
     ClipperLib::Polygons clipper_subject = tgPolygon::ToClipper( subject );
     ClipperLib::Polygons clipper_clip    = tgPolygon::ToClipper( clip );
@@ -2073,6 +2162,8 @@ tgPolygon tgPolygon::Intersect( const tgPolygon& subject, const tgPolygon& clip
     c.Execute(ClipperLib::ctIntersection, clipper_result, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd);
 
     result = tgPolygon::FromClipper( clipper_result );
+    result = tgPolygon::AddColinearNodes( result, all_nodes );
+
     result.SetMaterial( subject.GetMaterial() );
     result.SetTexParams( subject.GetTexParams() );
 
@@ -2125,6 +2216,14 @@ void tgPolygon::AccumulatorToShapefiles( const std::string& path, const std::str
 tgPolygon tgPolygon::DiffWithAccumulator( const tgPolygon& subject )
 {
     tgPolygon result;
+    TGTriNodes all_nodes;
+
+    /* before diff - gather all nodes */
+    for ( unsigned int i = 0; i < subject.Contours(); ++i ) {
+        for ( unsigned int j = 0; j < subject.ContourSize( i ); ++j ) {
+            all_nodes.unique_add( Point3D::fromSGGeod( subject.GetNode(i, j) ) );
+        }
+    }
 
     unsigned int  num_hits = 0;
     tg::Rectangle box1 = subject.GetBoundingBox();
@@ -2153,10 +2252,9 @@ tgPolygon tgPolygon::DiffWithAccumulator( const tgPolygon& subject )
             SG_LOG(SG_GENERAL, SG_ALERT, "Diff With Accumulator returned FALSE" );
             exit(-1);
         }
-        SG_LOG(SG_GENERAL, SG_ALERT, "Diff With Accumulator had " << num_hits << " hits " );
-        SG_LOG(SG_GENERAL, SG_ALERT, "  cklipper_result has " << clipper_result.size() << " contours " );
 
         result = tgPolygon::FromClipper( clipper_result );
+        result = tgPolygon::AddColinearNodes( result, all_nodes );
 
         // Make sure we keep texturing info
         result.SetMaterial( subject.GetMaterial() );
@@ -2222,7 +2320,7 @@ void tgPolygon::RemoveSlivers( tgPolygon& subject, tgcontour_list& slivers )
             // And add it to the slive list if it isn't a hole
             if ( !contour.GetHole() ) {
                 // move sliver contour to sliver list
-                SG_LOG(SG_GENERAL, SG_INFO, "      Found SLIVER!");
+                SG_LOG(SG_GENERAL, SG_DEBUG, "      Found SLIVER!");
 
                 slivers.push_back( contour );
             }
@@ -2567,7 +2665,7 @@ static void ClipToFile( const tgPolygon& subject, std::string root,
         SG_LOG(SG_GENERAL, SG_DEBUG, "   hole = " << subject.GetContour(ii).GetHole() );
     }
 
-    result = tgPolygon::Intersect( base, subject );
+    result = tgPolygon::Intersect( subject, base );
 
     SG_LOG(SG_GENERAL, SG_DEBUG, "result contours = " << result.Contours() );
     for ( unsigned int ii = 0; ii < result.Contours(); ii++ ) {

src/Lib/Polygon/polygon.hxx

@@ -588,6 +588,7 @@ public:
     // TODO : Both should be constant
     // what we really need is multiple accumulators
     // init_accumulator should return a handle...
+    static void      SetDump( bool dmp );
     static tgPolygon Union( const tgContour& subject, tgPolygon& clip );
     static tgPolygon Union( const tgPolygon& subject, tgPolygon& clip );
     static tgPolygon Diff( const tgPolygon& subject, tgPolygon& clip );