Reversing the order of points causes the area calculation to return a

negative number.  Polygon holes are wound opposite of non-holes.  I was
throwing out holes with area < epsilon (i.e. all holes) ... enough said.

diff --git a/Tools/Construct/Clipper/clipper.cxx b/Tools/Construct/Clipper/clipper.cxx
index db1bfeb7b81e93d01061eb745b7cf0960a8a1b1e..fc8ae0f5b9b987d9ac7f62beeed4dd234f7dd647 100644 (file)
--- a/Tools/Construct/Clipper/clipper.cxx
+++ b/Tools/Construct/Clipper/clipper.cxx
@@ -183,7 +183,7 @@ void FGClipper::move_slivers( FGPolygon& in, FGPolygon& out ) {
        cout << "  area = " << area << endl;
 
        if ( ((min_angle < angle_cutoff) && (area < area_cutoff)) ||
-            (area < area_cutoff / 10.0) )
+            ( area < area_cutoff / 10.0) )
        {
            cout << "      WE THINK IT'S A SLIVER!" << endl;
 
@@ -192,6 +192,7 @@ void FGClipper::move_slivers( FGPolygon& in, FGPolygon& out ) {
 
            if ( hole_flag ) {
                // just delete/eliminate/remove sliver holes
+               cout << "just deleting a sliver hole" << endl;
                in.delete_contour( i );
            } else {
                // move sliver contour to out polygon
@@ -259,6 +260,9 @@ void FGClipper::merge_slivers( FGPolyList& clipped, FGPolygon& slivers ) {
                }
            }
        }
+       if ( !done ) {
+           cout << "no suitable polys found for sliver merge" << endl;
+       }
     }
 }
 

diff --git a/Tools/Construct/Triangulate/polygon.cxx b/Tools/Construct/Triangulate/polygon.cxx
index 142f231f653439d54e516bb76a142197a55cd593..cc6ff9040aa57c292825a43136f3f1ac9e5b2452 100644 (file)
--- a/Tools/Construct/Triangulate/polygon.cxx
+++ b/Tools/Construct/Triangulate/polygon.cxx
@@ -88,8 +88,19 @@ static double calc_angle(point2d a, point2d b, point2d c) {
 // the y value of a point on the line that intersects with the
 // verticle line through x.  Return true if an intersection is found,
 // false otherwise.
-static bool intersects( const Point3D& p0, const Point3D& p1, double x, 
-                        Point3D *result ) {
+static bool intersects( Point3D p0, Point3D p1, double x, Point3D *result ) {
+    // sort the end points
+    if ( p0.x() > p1.x() ) {
+       Point3D tmp = p0;
+       p0 = p1;
+       p1 = tmp;
+    }
+    
+    if ( (x < p0.x()) || (x > p1.x()) ) {
+       // out of range of line segment, bail right away
+       return false;
+    }
+
     // equation of a line through (x0,y0) and (x1,y1):
     // 
     //     y = y1 + (x - x1) * (y0 - y1) / (x0 - x1)
@@ -206,7 +217,7 @@ void FGPolygon::calc_point_inside( const int contour,
            p2_index = trinodes.find( p2 );
        
            if ( intersects(p1, p2, m.x(), &result) ) {
-               // cout << "intersection = " << result << endl;
+               cout << "intersection = " << result << endl;
                if ( ( result.y() < p3.y() ) &&
                     ( result.y() > m.y() ) &&
                     ( base_leg != FGTriSeg(p1_index, p2_index) ) ) {
@@ -221,7 +232,7 @@ void FGPolygon::calc_point_inside( const int contour,
        p1_index = trinodes.find( p1 );
        p2_index = trinodes.find( p2 );
        if ( intersects(p1, p2, m.x(), &result) ) {
-           // cout << "intersection = " << result << endl;
+           cout << "intersection = " << result << endl;
            if ( ( result.y() < p3.y() ) &&
                 ( result.y() > m.y() ) &&
                 ( base_leg != FGTriSeg(p1_index, p2_index) ) ) {
@@ -259,7 +270,9 @@ double FGPolygon::area_contour( const int contour ) {
        sum += c[(i+1)%size].x() * c[i].y() - c[i].x() * c[(i+1)%size].y();
     }
 
-    return sum / 2.0;
+    // area can be negative or positive depending on the polygon
+    // winding order
+    return fabs(sum / 2.0);
 }
 
 
@@ -454,6 +467,3 @@ FGPolygon polygon_xor( const FGPolygon& subject, const FGPolygon& clip ) {
 FGPolygon polygon_union( const FGPolygon& subject, const FGPolygon& clip ) {
     return polygon_clip( POLY_UNION, subject, clip );
 }
-
-
-

diff --git a/Tools/Construct/Triangulate/triangle.cxx b/Tools/Construct/Triangulate/triangle.cxx
index 88feafda02d1ec30d750e934191e4f9f06591f52..a8e3572352e684768e8cae244758471ad97fa27a 100644 (file)
--- a/Tools/Construct/Triangulate/triangle.cxx
+++ b/Tools/Construct/Triangulate/triangle.cxx
@@ -41,7 +41,6 @@ FGTriangle::build( const point_list& corner_list,
                   const FGPolyList& gpc_polys )
 {
     int debug_counter = 0;
-    FGPolygon poly;
     int index;
 
     in_nodes.clear();
@@ -75,12 +74,13 @@ FGTriangle::build( const point_list& corner_list,
     for ( int i = 0; i < FG_MAX_AREA_TYPES; ++i ) {
        polylist[i].clear();
 
-       // cout << "area type = " << i << endl;
+       cout << "area type = " << i << endl;
        debug_counter = 0;
        current = gpc_polys.polys[i].begin();
        last = gpc_polys.polys[i].end();
        for ( ; current != last; ++current ) {
            gpc_poly = *current;
+
            cout << "processing a polygon, contours = " 
                 << gpc_poly.contours() << endl;
 
@@ -89,10 +89,7 @@ FGTriangle::build( const point_list& corner_list,
                exit(-1);
            }
 
-           poly.erase();
-
            int j;
-
            for ( j = 0; j < gpc_poly.contours(); ++j ) {
                cout << "  processing contour = " << j << ", nodes = " 
                     << gpc_poly.contour_size( j ) << ", hole = "
@@ -106,47 +103,49 @@ FGTriangle::build( const point_list& corner_list,
                    index = in_nodes.unique_add( p );
                    // junkp = in_nodes.get_node( index );
                    // fprintf(junkfp, "%.4f %.4f\n", junkp.x(), junkp.y());
-                   poly.add_node(j, p);
                    // cout << "  - " << index << endl;
                }
                // fprintf(junkfp, "%.4f %.4f\n", 
                //    gpc_poly->contour[j].vertex[0].x, 
                //    gpc_poly->contour[j].vertex[0].y);
                // fclose(junkfp);
-
-               poly.set_hole_flag( j, gpc_poly.get_hole_flag( j ) );
            }
 
            for ( j = 0; j < gpc_poly.contours(); ++j ) {
-               poly.calc_point_inside( j, in_nodes );
+               gpc_poly.calc_point_inside( j, in_nodes );
            }
 
+           polylist[i].push_back( gpc_poly );
+
 #if 0
            // temporary ... write out hole/polygon info for debugging
-           for ( j = 0; j < (int)poly.contours(); ++j ) {
+           for ( j = 0; j < (int)gpc_poly.contours(); ++j ) {
                char pname[256];
                sprintf(pname, "poly%02d-%02d-%02d", i, debug_counter, j);
+               cout << "writing to " << pname << endl;
                FILE *fp = fopen( pname, "w" );
                Point3D point;
-               for ( int k = 0; k < poly.contour_size( j ); ++k ) {
-                   point = poly.get_pt( j, k );
+               for ( int k = 0; k < gpc_poly.contour_size( j ); ++k ) {
+                   point = gpc_poly.get_pt( j, k );
                    fprintf( fp, "%.6f %.6f\n", point.x(), point.y() );
                }
-               point = poly.get_pt( j, 0 );
+               point = gpc_poly.get_pt( j, 0 );
                fprintf( fp, "%.6f %.6f\n", point.x(), point.y() );
                fclose(fp);
 
                char hname[256];
                sprintf(hname, "hole%02d-%02d-%02d", i, debug_counter, j);
                FILE *fh = fopen( hname, "w" );
-               point = poly.get_point_inside( j );
+               point = gpc_poly.get_point_inside( j );
                fprintf( fh, "%.6f %.6f\n", point.x(), point.y() );
                fclose(fh);
            }
-#endif
-
-           polylist[i].push_back( poly );
 
+           // cout << "type a letter + enter to continue: ";
+           // string input;
+           // cin >> input;
+#endif
+               
            ++debug_counter;
        }
     }
@@ -172,6 +171,8 @@ FGTriangle::build( const point_list& corner_list,
     int i1, i2;
     Point3D p1, p2;
     point_list node_list = in_nodes.get_node_list();
+    FGPolygon poly;
+
     for ( int i = 0; i < FG_MAX_AREA_TYPES; ++i ) {
        cout << "area type = " << i << endl;
        poly_list_iterator tp_current, tp_last;