Geometry Boost List: [geometry] How get shape to draw from polygon?

From: 0xtrzy_at_[hidden]
Date: 2020-06-18 20:32:34

Hello,   I have a multi polygon from union two shapes. I would like to draw multipolygon on screen.  Therefore I need a shape to draw. If my polygon no have holes it is simple. But if it have one or more its trouble. How draw a shapes (list of points) from polygon?  for example char 'A' to two separate polygon  ibb.co ibb.co   P.S. What I can check clockwise of polygons in multipolygon? Simply i can check  std::cout << " simple? " << (boost::geometry::is_simple(p) ? "yes" : "no") << std::endl;  How checking each shape in Polygon?  P.S.S. How set a clockwise one ring?   ----  #include <iostream>  #include <deque>   #include <boost/geometry.hpp>  #include <boost/geometry/geometries/poi  #include <boost/geometry/geometries/pol  #include <boost/geometry/geometries/reg   #include <boost/foreach.hpp>   typedef boost::geometry::model::d2::po point_t;  typedef boost::geometry::model::polygo polygon_t;  typedef boost::geometry::model::multi_ mpolygon_t;   BOOST_GEOMETRY_REGISTER_MULTI_   int main()  {  std::deque<polygon_t> green;  std::deque<polygon_t> blue;  std::deque<polygon_t> wynik;   boost::geometry::read_wkt("MUL 4, 3 1, 6 4, 3 0, 0 4)),((0 3, 0.1 3, 0.1 3.5, 0 3.5, 0 3)))", green);   boost::geometry::correct(green  /* how change polygon[0].outer to clockwise or change to non clockwise */   BOOST_FOREACH(auto const& p, green)    {    std::cout << j++ << ": " << boost::geometry::wkt(p);    std::cout << " simple? " << (boost::geometry::is_simple(p) ? "yes" : "no") << std::endl;     auto zew = p.outer();    k = 0;    for (auto i = std::begin(zew); i != std::end(zew); ++i)     {     std::cout << ":: "<< k++ << " [" << i->x() << " " << i->y() << "] " << std::endl;     }     }    blue.resize(1); /* domyślnie jest puste */  boost::geometry::read_wkt("POL 0, 3 4, 6 0, 3 3))", blue[0]);  boost::geometry::correct(blue) /* poprawiamy */   boost::geometry::union_(green, blue, wynik);  std::cout << "\n shape (" << wynik.size() << ") " <<      "green (lub || unia) blue:" << std::endl;   std::cout << "result:" << boost::geometry::wkt(wynik) << std::endl;  BOOST_FOREACH(polygon_t const& v, wynik)      std::cout << boost::geometry::wkt<polygon_t << std::endl;   /* how get shapes */   return 0;  }