From f01a1daa7b28729a3be5d1297744055682cc0f57 Mon Sep 17 00:00:00 2001
From: Ralf Gerlich <ralf.gerlich@custom-scenery.org>
Date: Fri, 8 Feb 2008 22:24:42 +0100
Subject: [PATCH] Fixed criterion for removal of small degenerate polygons.

---
 src/Airports/GenAirports/build.cxx |  4 ++
 src/Lib/Geometry/poly_support.cxx  | 64 ++++++++++++++++--------------
 src/Lib/Geometry/poly_support.hxx  |  3 ++
 3 files changed, 42 insertions(+), 29 deletions(-)

diff --git a/src/Airports/GenAirports/build.cxx b/src/Airports/GenAirports/build.cxx
index db669301..2bbef0fb 100644
--- a/src/Airports/GenAirports/build.cxx
+++ b/src/Airports/GenAirports/build.cxx
@@ -802,6 +802,8 @@ void build_airport( string airport_id, float alt_m,
 	SG_LOG(SG_GENERAL, SG_DEBUG, "total size after remove_dups() = " << poly.total_size());
         poly = remove_bad_contours( poly );
 	SG_LOG(SG_GENERAL, SG_DEBUG, "total size after remove_bad() = " << poly.total_size());
+        poly = remove_tiny_contours( poly );
+	SG_LOG(SG_GENERAL, SG_DEBUG, "total size after remove_tiny_contours() = " << poly.total_size());
 
 	rwy_polys[k].set_poly( poly );
     }
@@ -818,6 +820,8 @@ void build_airport( string airport_id, float alt_m,
     base_poly = remove_dups( base_poly );
     SG_LOG(SG_GENERAL, SG_DEBUG, "remove bad contours base");
     base_poly = remove_bad_contours( base_poly );
+    SG_LOG(SG_GENERAL, SG_DEBUG, "remove small contours base");
+    base_poly = remove_tiny_contours( base_poly );
     // write_polygon( base_poly, "base-fin" );
     SG_LOG(SG_GENERAL, SG_DEBUG, " after clean up: " << base_poly);
 
diff --git a/src/Lib/Geometry/poly_support.cxx b/src/Lib/Geometry/poly_support.cxx
index f343fe3d..5e56eff5 100644
--- a/src/Lib/Geometry/poly_support.cxx
+++ b/src/Lib/Geometry/poly_support.cxx
@@ -414,25 +414,28 @@ static void collect_contour_points( TGContourNode* node, TGPolygon &p, point_lis
 
 static void write_tree_element( TGContourNode *node, TGPolygon& p, int hole=0) {
     int contour_num = node->get_contour_num();
-    char buf[256];
-    sprintf(buf, "failed/element%ld.poly",contour_num);
-    FILE *treefp = fopen(buf,"w");
     
-    fprintf(treefp,"#2D\n");
-    fprintf(treefp,"Airport\n");
-    
-    fprintf(treefp,"1\n");
-    
-    fprintf(treefp,"%ld\n",p.contour_size(contour_num));
-    fprintf(treefp,"%d\n",hole);
-    
-    for (int i=0;i<p.contour_size(contour_num);i++) {
-            Point3D pt=p.get_pt(contour_num,i);
-            fprintf(treefp,"%.15f %.15f\n",pt.x(),pt.y());
+    if (contour_num != -1) {
+            char buf[256];
+            sprintf(buf, "failed/element%ld.poly",contour_num);
+            FILE *treefp = fopen(buf,"w");
+            
+            fprintf(treefp,"#2D\n");
+            fprintf(treefp,"Airport\n");
+            
+            fprintf(treefp,"1\n");
+            
+            fprintf(treefp,"%ld\n",p.contour_size(contour_num));
+            fprintf(treefp,"%d\n",hole);
+            
+            for (int i=0;i<p.contour_size(contour_num);i++) {
+                    Point3D pt=p.get_pt(contour_num,i);
+                    fprintf(treefp,"%.15f %.15f\n",pt.x(),pt.y());
+            }
+            
+            fclose(treefp);
     }
     
-    fclose(treefp);
-    
     for ( int i = 0; i < node->get_num_kids(); ++i ) {
             if ( node->get_kid( i ) != NULL ) {
                     write_tree_element( node->get_kid( i ), p, 1-hole);
@@ -507,10 +510,6 @@ static void calc_point_inside( TGContourNode *node, TGPolygon &p ) {
 
     // cout << "calc_point_inside() maxdiff=" << maxdiff << " yline=" << yline << endl;
     
-    if (maxdiff < SG_EPSILON) {
-            throw sg_exception("Polygon is too small in y-direction");
-    }
-    
     vector < double > xcuts;
     
     intersect_yline_with_contour( yline, node, p, xcuts );
@@ -1042,18 +1041,25 @@ TGPolygon remove_bad_contours( const TGPolygon &poly ) {
 	    continue;
         }
         
-        point_list allpoints = contour;
-        
-        sort(allpoints.begin(), allpoints.end(), Point3DOrdering(PY));
-        
-        point_list::iterator point_it;
-        
-        point_it=allpoints.begin();
-        Point3D lastpt=*point_it;
+	/* keeping the contour */
+	int flag = poly.get_hole_flag( i );
+	result.add_contour( contour, flag );
+    }
+
+    return result;
+}
+
+// remove any too small contours
+TGPolygon remove_tiny_contours( const TGPolygon &poly ) {
+    TGPolygon result;
+    result.erase();
+
+    for ( int i = 0; i < poly.contours(); ++i ) {
+	point_list contour = poly.get_contour( i );
         
         double area=poly.area_contour(i);
         
-        if (-SG_EPSILON<area && area<SG_EPSILON) {
+        if (-SG_EPSILON*SG_EPSILON<area && area<SG_EPSILON*SG_EPSILON) {
             // cout << "tossing a bad contour " << i << " (too small)" << endl;
             continue;
         }
diff --git a/src/Lib/Geometry/poly_support.hxx b/src/Lib/Geometry/poly_support.hxx
index b6afed3e..231247b1 100644
--- a/src/Lib/Geometry/poly_support.hxx
+++ b/src/Lib/Geometry/poly_support.hxx
@@ -95,6 +95,9 @@ bool find_intermediate_node( const Point3D& start, const Point3D& end,
 // remove any degenerate contours
 TGPolygon remove_bad_contours( const TGPolygon &poly );
 
+// remove any too small contours
+TGPolygon remove_tiny_contours( const TGPolygon &poly );
+
 
 #endif // _POLY_SUPPORT_HXX