polygon_diff.cpp

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// difference between polygons

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Polygon_2.h>
#include <CGAL/Polygon_with_holes_2.h>
#include <CGAL/Boolean_set_operations_2.h>

#include "global.h"

using namespace std;

// exact kernel
typedef CGAL::Exact_predicates_exact_constructions_kernel               EK;
typedef EK::Point_2                                                                                             EPoint_2;
typedef CGAL::Polygon_2<EK>                                                                             EPolygon_2;
typedef CGAL::Polygon_with_holes_2<EK>                                                  EPolygon_with_holes_2;
typedef std::list<EPolygon_with_holes_2>                                                EPwh_list_2;

// main
int main(int argc, char* argv[])
{
/*
        if (argc == 5)
        {
                //cerr<<"program                   "<<argv[0]<<endl;
                //cerr<<"domainFilePath  "<<argv[1]<<endl;
                //cerr<<"holeFilePath    "<<argv[2]<<endl;
                //cerr<<"resultFilePath  "<<argv[3]<<endl;
                //cerr<<"communicateFile "<<argv[4]<<endl;
                domainFilePath = argv[1];
                holeFilePath = argv[2];
                resultFilePath = argv[3];
                communicateFile = argv[4];
        }
//*/
        cerr<<"diff between polygons...";
        // set up
        ifstream ifs(communicateFile.c_str());
        int process_num = 0;
        ifs >> process_num;
        ifs.clear();
        ifs.close();
        // load polygons
        EPolygon_with_holes_2 eDomain;
        ifs.open(domainFilePath.c_str());
        ifs >> eDomain;
        ifs.clear();
        ifs.close();
        EPolygon_2 eHole;
        ifs.open(holeFilePath.c_str());
        ifs >> eHole;
        ifs.clear();
        ifs.close();
        // add noise or not. avoid numerical error.
        if (process_num == -1)
        {
                // noise domain outer boundary
                {
                        srand((unsigned)time(NULL));
                        vector<EPoint_2> temp;
                        for (int i = 0; i < eDomain.outer_boundary().size(); i++)
                                temp.push_back(EPoint_2(eDomain.outer_boundary()[i].x() + (double)rand() / RAND_MAX / 10, eDomain.outer_boundary()[i].y() + (double)rand() / RAND_MAX / 10));
                        eDomain.outer_boundary() = EPolygon_2(temp.begin(), temp.end());
                }
                // noise hole
                {
                        srand((unsigned)time(NULL));
                        vector<EPoint_2> temp;
                        for (int i = 0; i < eHole.size(); i++)
                                temp.push_back(EPoint_2(eHole[i].x() + (double)rand() / RAND_MAX / 10, eHole[i].y() + (double)rand() / RAND_MAX / 10));
                        eHole = EPolygon_2(temp.begin(), temp.end());
                }
        }
        // compute difference
        EPwh_list_2 eList;
        CGAL::difference(eDomain, eHole, back_inserter(eList));
        // result
        if (eList.size() == 0)
        {
                ofstream ofs(communicateFile.c_str());
                ofs << 2 << endl;
                ofs.clear();
                ofs.close();
                return -1;
        }
        // get domain result
        EPolygon_with_holes_2 ePass;
        if (eList.size() != 1) // if domain become not continious
        {
                auto j = eList.begin();
                CGAL::Lazy_exact_nt<CGAL::Quotient<CGAL::Gmpq> > max_area = 0;
                for (auto i = eList.begin(); i != eList.end(); i++)
                {
                        if ((i->outer_boundary().area())*(i->outer_boundary().area()) > max_area*max_area)
                        {
                                max_area = i->outer_boundary().area();
                                j = i;
                        }
                }
                ePass = EPolygon_with_holes_2(*j);
        }
        else // domain continious
        {
                ePass = EPolygon_with_holes_2(*eList.begin());
        }
        // save result and feedback
        ofstream ofs(communicateFile.c_str());
        ofs << 1 << endl;
        ofs.clear();
        ofs.close();
        ofs.open(resultFilePath.c_str());
        ofs << ePass;
        ofs.clear();
        ofs.close();
        // end.
        cerr << "done." << endl;
        return 0;
}