f13b3855c1
After I clip a polygon against the more important stuff, I check the area and minimum interior angle of each of it's contours. If both (area and min interior angle) are below some threshhold I'm calling it a sliver. Then I go and look for another polygon such that result = polygon_union( poly, sliver ) yields a result that doesn't have anymore contours than the original poly. This means the sliver is adjacent to poly. So I replace poly with result (the union) and keep going.
168 lines
4.4 KiB
C++
168 lines
4.4 KiB
C++
// polygon.hxx -- polygon (with holes) management class
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//
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// Written by Curtis Olson, started March 1999.
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//
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// Copyright (C) 1999 Curtis L. Olson - curt@flightgear.org
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License as
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// published by the Free Software Foundation; either version 2 of the
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// License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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//
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// $Id$
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#ifndef _POLYGON_HXX
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#define _POLYGON_HXX
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#ifndef __cplusplus
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# error This library requires C++
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#endif
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#include <Include/compiler.h>
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#include <string>
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#include <vector>
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#include <Main/construct_types.hxx>
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#include "trinodes.hxx"
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FG_USING_STD(string);
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FG_USING_STD(vector);
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#define FG_MAX_VERTICES 100000
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typedef vector < point_list > polytype;
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typedef polytype::iterator polytype_iterator;
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typedef polytype::const_iterator const_polytype_iterator;
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class FGPolygon {
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private:
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polytype poly; // polygons
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point_list inside_list; // point inside list
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int_list hole_list; // hole flag list
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public:
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// Constructor and destructor
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FGPolygon( void );
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~FGPolygon( void );
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// Add a contour
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inline void add_contour( const point_list contour, const int hole_flag ) {
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poly.push_back( contour );
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hole_list.push_back( hole_flag );
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}
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// Get a contour
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inline point_list get_contour( const int i ) const {
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return poly[i];
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}
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// Delete a contour
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inline void delete_contour( const int i ) {
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polytype_iterator start_poly = poly.begin();
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poly.erase( start_poly + i );
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int_list_iterator start_hole = hole_list.begin();
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hole_list.erase( start_hole + i );
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}
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// Add the specified node (index) to the polygon
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inline void add_node( int contour, Point3D p ) {
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if ( contour >= (int)poly.size() ) {
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// extend polygon
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point_list empty_contour;
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empty_contour.clear();
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for ( int i = 0; i < contour - (int)poly.size() + 1; ++i ) {
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poly.push_back( empty_contour );
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inside_list.push_back( Point3D(0.0) );
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hole_list.push_back( 0 );
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}
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}
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poly[contour].push_back( p );
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}
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// return size
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inline int contours() const { return poly.size(); }
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inline int contour_size( int contour ) const {
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return poly[contour].size();
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}
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// return the ith polygon point index from the specified contour
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inline Point3D get_pt( int contour, int i ) const {
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return poly[contour][i];
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}
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// calculate some "arbitrary" point inside the specified contour for
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// assigning attribute areas
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void calc_point_inside( const int contour, const FGTriNodes& trinodes );
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inline Point3D get_point_inside( const int contour ) const {
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return inside_list[contour];
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}
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// get and set hole flag
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inline int get_hole_flag( const int contour ) const {
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return hole_list[contour];
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}
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inline void set_hole_flag( const int contour, const int flag ) {
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hole_list[contour] = flag;
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}
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// erase
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inline void erase() { poly.clear(); }
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// informational
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// return the area of a contour (assumes simple polygons,
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// i.e. non-self intersecting.)
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double area_contour( const int contour );
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// return the smallest interior angle of the polygon
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double minangle_contour( const int contour );
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// output
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void write( const string& file );
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};
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typedef vector < FGPolygon > poly_list;
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typedef poly_list::iterator poly_list_iterator;
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typedef poly_list::const_iterator const_poly_list_iterator;
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// wrapper functions for gpc polygon clip routines
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// Difference
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FGPolygon polygon_diff( const FGPolygon& subject, const FGPolygon& clip );
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// Intersection
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FGPolygon polygon_int( const FGPolygon& subject, const FGPolygon& clip );
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// Exclusive or
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FGPolygon polygon_xor( const FGPolygon& subject, const FGPolygon& clip );
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// Union
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FGPolygon polygon_union( const FGPolygon& subject, const FGPolygon& clip );
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#endif // _POLYGON_HXX
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