// Boost.Geometry (aka GGL, Generic Geometry Library) // QuickBook Example // Copyright (c) 2015, Oracle and/or its affiliates // Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle // Licensed under the Boost Software License version 1.0. // http://www.boost.org/users/license.html //[is_valid_message //` Checks whether a geometry is valid and, if not valid, prints a message describing the reason #include <iostream> #include <string> #include <boost/geometry.hpp> #include <boost/geometry/geometries/point_xy.hpp> #include <boost/geometry/geometries/polygon.hpp> /*<-*/ #include "create_svg_one.hpp" /*->*/ int main() { typedef boost::geometry::model::d2::point_xy<double> point_type; typedef boost::geometry::model::polygon<point_type> polygon_type; polygon_type poly; boost::geometry::read_wkt("POLYGON((0 0,0 10,10 10,10 0,0 0),(0 0,9 1,9 2,0 0),(0 0,2 9,1 9,0 0),(2 9,9 2,9 9,2 9))", poly); std::string message; bool valid = boost::geometry::is_valid(poly, message); std::cout << "is valid? " << (valid ? "yes" : "no") << std::endl; if (! valid) { std::cout << "why not valid? " << message << std::endl; } /*<-*/ create_svg("is_valid_example.svg", poly); /*->*/ return 0; } //] //[is_valid_message_output /*` Output: [pre is valid? no why not valid? Geometry has disconnected interior [$img/algorithms/is_valid_example.png] ] */ //]