--- /dev/null
+// tripoly.cxx -- "Triangle" polygon management class
+//
+// Written by Curtis Olson, started March 1999.
+//
+// Copyright (C) 1999 Curtis L. Olson - curt@flightgear.org
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+// (Log is kept at end of this file)
+
+
+#include <Include/fg_constants.h>
+#include <Math/point3d.hxx>
+
+#include "tripoly.hxx"
+
+
+// Constructor
+FGTriPoly::FGTriPoly( void ) {
+}
+
+
+// Destructor
+FGTriPoly::~FGTriPoly( void ) {
+}
+
+
+// Given a line segment specified by two endpoints p1 and p2, return
+// the slope of the line.
+static double slope( const Point3D& p0, const Point3D& p1 ) {
+ if ( fabs(p0.x() - p1.x()) > FG_EPSILON ) {
+ return (p0.y() - p1.y()) / (p0.x() - p1.x());
+ } else {
+ return 1.0e+999; // really big number
+ }
+}
+
+
+// Given a line segment specified by two endpoints p1 and p2, return
+// 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 ) {
+ // equation of a line through (x0,y0) and (x1,y1):
+ //
+ // y = y1 + (x - x1) * (y0 - y1) / (x0 - x1)
+
+ double y;
+
+ if ( fabs(p0.x() - p1.x()) > FG_EPSILON ) {
+ y = p1.y() + (x - p1.x()) * (p0.y() - p1.y()) / (p0.x() - p1.x());
+ } else {
+ return false;
+ }
+ result->setx(x);
+ result->sety(y);
+
+ if ( p0.y() <= p1.y() ) {
+ if ( (p0.y() <= y) && (y <= p1.y()) ) {
+ return true;
+ }
+ } else {
+ if ( (p0.y() >= y) && (y >= p1.y()) ) {
+ return true;
+ }
+ }
+
+ return false;
+}
+
+
+// calculate an "arbitrary" point inside this polygon for assigning
+// attribute areas
+void FGTriPoly::calc_point_inside( const FGTriNodes& trinodes ) {
+ Point3D tmp, min, ln, p1, p2, p3, m, result;
+
+ // 1. find point, min, with smallest y
+
+ // min.y() starts greater than the biggest possible lat (degrees)
+ min.sety( 100.0 );
+ // int min_index;
+ int min_node_index = 0;
+
+ tripoly_iterator current, last;
+ current = poly.begin();
+ last = poly.end();
+
+ int counter = 0;
+ for ( ; current != last; ++current ) {
+ tmp = trinodes.get_node( *current );
+ if ( tmp.y() < min.y() ) {
+ min = tmp;
+ // min_index = *current;
+ min_node_index = counter;
+
+ // cout << "min index = " << *current
+ // << " value = " << min_y << endl;
+ } else {
+ // cout << " index = " << *current << endl;
+ }
+ ++counter;
+ }
+ cout << "min node index = " << min_node_index << endl;
+ cout << "min index = " << poly[min_node_index]
+ << " value = " << trinodes.get_node( poly[min_node_index] )
+ << " == " << min << endl;
+
+ // 2. take midpoint, m, of min with neighbor having lowest
+ // fabs(slope)
+
+ if ( min_node_index == 0 ) {
+ p1 = trinodes.get_node( poly[1] );
+ p2 = trinodes.get_node( poly[poly.size() - 1] );
+ } else if ( min_node_index == (int)(poly.size()) - 1 ) {
+ p1 = trinodes.get_node( poly[0] );
+ p2 = trinodes.get_node( poly[poly.size() - 1] );
+ } else {
+ p1 = trinodes.get_node( poly[min_node_index - 1] );
+ p2 = trinodes.get_node( poly[min_node_index + 1] );
+ }
+ double s1 = fabs( slope(min, p1) );
+ double s2 = fabs( slope(min, p2) );
+ if ( s1 < s2 ) {
+ ln = p1;
+ } else {
+ ln = p2;
+ }
+
+ m.setx( (min.x() + ln.x()) / 2.0 );
+ m.sety( (min.y() + ln.y()) / 2.0 );
+ cout << "low mid point = " << m << endl;
+
+ // 3. intersect vertical line through m and all other segments.
+ // save point, p3, with smallest y > m.y
+
+ p3.sety(100);
+ for ( int i = 0; i < (int)(poly.size()) - 1; ++i ) {
+ p1 = trinodes.get_node( poly[i] );
+ p2 = trinodes.get_node( poly[i+1] );
+
+ if ( intersects(p1, p2, m.x(), &result) ) {
+ // cout << "intersection = " << result << endl;
+ if ( ( result.y() < p3.y() ) &&
+ ( fabs(result.y() - m.y()) > FG_EPSILON ) ) {
+ p3 = result;
+ }
+ }
+ }
+ p1 = trinodes.get_node( poly[0] );
+ p2 = trinodes.get_node( poly[poly.size() - 1] );
+ if ( intersects(p1, p2, m.x(), &result) ) {
+ // cout << "intersection = " << result << endl;
+ if ( ( result.y() < p3.y() ) &&
+ ( fabs(result.y() - m.y()) > FG_EPSILON ) ) {
+ p3 = result;
+ }
+ }
+ cout << "low intersection of other segment = " << p3 << endl;
+
+ // 4. take midpoint of p2 && m as an arbitrary point inside polygon
+
+ inside.setx( (m.x() + p3.x()) / 2.0 );
+ inside.sety( (m.y() + p3.y()) / 2.0 );
+ cout << "inside point = " << inside << endl;
+}
+
+
+// $Log$
+// Revision 1.1 1999/03/20 13:21:36 curt
+// Initial revision.
+//
--- /dev/null
+// tripoly.hxx -- "Triangle" polygon management class
+//
+// Written by Curtis Olson, started March 1999.
+//
+// Copyright (C) 1999 Curtis L. Olson - curt@flightgear.org
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+// (Log is kept at end of this file)
+
+
+#ifndef _TRIPOLY_HXX
+#define _TRIPOLY_HXX
+
+
+#ifndef __cplusplus
+# error This library requires C++
+#endif
+
+
+#include <Include/compiler.h>
+
+#include <vector>
+
+#include "trinodes.hxx"
+
+FG_USING_STD(vector);
+
+
+typedef vector < int > tripoly;
+typedef tripoly::iterator tripoly_iterator;
+typedef tripoly::const_iterator const_tripoly_iterator;
+
+
+class FGTriPoly {
+
+private:
+
+ tripoly poly;
+ Point3D inside;
+
+public:
+
+ // Constructor and destructor
+ FGTriPoly( void );
+ ~FGTriPoly( void );
+
+ // Add the specified node (index) to the polygon
+ inline void add_node( int index ) { poly.push_back( index ); }
+
+ // return size
+ inline int size() const { return poly.size(); }
+
+ // calculate an "arbitrary" point inside this polygon for
+ // assigning attribute areas
+ void calc_point_inside( const FGTriNodes& trinodes );
+};
+
+
+#endif // _TRIPOLY_HXX
+
+
+// $Log$
+// Revision 1.1 1999/03/20 13:21:36 curt
+// Initial revision.
+//
--- /dev/null
+// trisegs.cxx -- "Triangle" segment management class
+//
+// Written by Curtis Olson, started March 1999.
+//
+// Copyright (C) 1999 Curtis L. Olson - curt@flightgear.org
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+// (Log is kept at end of this file)
+
+
+#include "trisegs.hxx"
+
+
+// $Log$
+// Revision 1.1 1999/03/20 13:21:36 curt
+// Initial revision.
+//
--- /dev/null
+// trisegs.hxx -- "Triangle" segment management class
+//
+// Written by Curtis Olson, started March 1999.
+//
+// Copyright (C) 1999 Curtis L. Olson - curt@flightgear.org
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation; either version 2 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+// (Log is kept at end of this file)
+
+
+#ifndef _TRISEGS_HXX
+#define _TRISEGS_HXX
+
+
+#ifndef __cplusplus
+# error This library requires C++
+#endif
+
+
+#include <Include/compiler.h>
+
+#include <vector>
+
+FG_USING_STD(vector);
+
+
+// a segment is two integer pointers into the node list
+class FGTriSeg {
+public:
+ int n1, n2;
+};
+
+
+typedef vector < FGTriSeg > triseg_list;
+typedef triseg_list::iterator triseg_list_iterator;
+typedef triseg_list::const_iterator const_triseg_list_iterator;
+
+
+class FGTriSegments {
+
+private:
+
+ triseg_list seg_list;
+
+public:
+
+ // Constructor and destructor
+ FGTriSegments( void );
+ ~FGTriSegments( void );
+
+ // Add a point to the point list if it doesn't already exist.
+ // Returns the index (starting at zero) of the point in the list.
+ int unique_add( const FGTriSeg& s );
+
+ // return the master node list
+ inline triseg_list get_seg_list() const { return seg_list; }
+
+ // return the ith segment
+ inline FGTriSeg get_seg( int i ) const { return seg_list[i]; }
+};
+
+
+#endif // _TRISEGS_HXX
+
+
+// $Log$
+// Revision 1.1 1999/03/20 13:21:36 curt
+// Initial revision.
+//
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