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- // Boost.Geometry (aka GGL, Generic Geometry Library)
- // Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
- // Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
- // Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
- // Use, modification and distribution is subject to the Boost Software License,
- // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt)
- //
- // Linestring Example
- #include <algorithm> // for reverse, unique
- #include <iostream>
- #include <iterator>
- #include <utility>
- #include <vector>
- #include <boost/geometry/geometry.hpp>
- #include <boost/geometry/geometries/linestring.hpp>
- #include <boost/geometry/geometries/point_xy.hpp>
- #include <boost/geometry/geometries/polygon.hpp>
- // Optional includes and defines to handle c-arrays as points, std::vectors as linestrings
- #include <boost/geometry/geometries/register/linestring.hpp>
- #include <boost/geometry/geometries/adapted/c_array.hpp>
- BOOST_GEOMETRY_REGISTER_C_ARRAY_CS(cs::cartesian)
- BOOST_GEOMETRY_REGISTER_LINESTRING_TEMPLATED(std::vector)
- BOOST_GEOMETRY_REGISTER_LINESTRING_TEMPLATED(std::deque)
- template<typename P>
- inline void translate_function(P& p)
- {
- p.x(p.x() + 100.0);
- }
- template<typename P>
- struct scale_functor
- {
- inline void operator()(P& p)
- {
- p.x(p.x() * 1000.0);
- p.y(p.y() * 1000.0);
- }
- };
- template<typename Point>
- struct round_coordinates
- {
- typedef typename boost::geometry::coordinate_type<Point>::type coordinate_type;
- coordinate_type m_factor;
- inline round_coordinates(coordinate_type const& factor)
- : m_factor(factor)
- {}
- template <int Dimension>
- inline void round(Point& p)
- {
- coordinate_type c = boost::geometry::get<Dimension>(p) / m_factor;
- int rounded = c;
- boost::geometry::set<Dimension>(p, coordinate_type(rounded) * m_factor);
- }
- inline void operator()(Point& p)
- {
- round<0>(p);
- round<1>(p);
- }
- };
- int main(void)
- {
- using namespace boost::geometry;
- // Define a linestring, which is a vector of points, and add some points
- // (we add them deliberately in different ways)
- typedef model::d2::point_xy<double> point_2d;
- typedef model::linestring<point_2d> linestring_2d;
- linestring_2d ls;
- // points can be created using "make" and added to a linestring using the std:: "push_back"
- ls.push_back(make<point_2d>(1.1, 1.1));
- // points can also be assigned using "assign_values" and added to a linestring using "append"
- point_2d lp;
- assign_values(lp, 2.5, 2.1);
- append(ls, lp);
- // Lines can be streamed using DSV (delimiter separated values)
- std::cout << dsv(ls) << std::endl;
- // The bounding box of linestrings can be calculated
- typedef model::box<point_2d> box_2d;
- box_2d b;
- envelope(ls, b);
- std::cout << dsv(b) << std::endl;
- // The length of the line can be calulated
- std::cout << "length: " << length(ls) << std::endl;
- // All things from std::vector can be called, because a linestring is a vector
- std::cout << "number of points 1: " << ls.size() << std::endl;
- // All things from boost ranges can be called because a linestring is considered as a range
- std::cout << "number of points 2: " << boost::size(ls) << std::endl;
- // Generic function from geometry/OGC delivers the same value
- std::cout << "number of points 3: " << num_points(ls) << std::endl;
- // The distance from a point to a linestring can be calculated
- point_2d p(1.9, 1.2);
- std::cout << "distance of " << dsv(p)
- << " to line: " << distance(p, ls) << std::endl;
- // A linestring is a vector. However, some algorithms consider "segments",
- // which are the line pieces between two points of a linestring.
- double d = distance(p, model::segment<point_2d >(ls.front(), ls.back()));
- std::cout << "distance: " << d << std::endl;
- // Add some three points more, let's do it using a classic array.
- // (See documentation for picture of this linestring)
- const double c[][2] = { {3.1, 3.1}, {4.9, 1.1}, {3.1, 1.9} };
- append(ls, c);
- std::cout << "appended: " << dsv(ls) << std::endl;
- // Output as iterator-pair on a vector
- {
- std::vector<point_2d> v;
- std::copy(ls.begin(), ls.end(), std::back_inserter(v));
- std::cout
- << "as vector: "
- << dsv(v)
- << std::endl;
- }
- // All algorithms from std can be used: a linestring is a vector
- std::reverse(ls.begin(), ls.end());
- std::cout << "reversed: " << dsv(ls) << std::endl;
- std::reverse(boost::begin(ls), boost::end(ls));
- // The other way, using a vector instead of a linestring, is also possible
- std::vector<point_2d> pv(ls.begin(), ls.end());
- std::cout << "length: " << length(pv) << std::endl;
- // If there are double points in the line, you can use unique to remove them
- // So we add the last point, print, make a unique copy and print
- {
- // (sidenote, we have to make copies, because
- // ls.push_back(ls.back()) often succeeds but
- // IS dangerous and erroneous!
- point_2d last = ls.back(), first = ls.front();
- ls.push_back(last);
- ls.insert(ls.begin(), first);
- }
- std::cout << "extra duplicate points: " << dsv(ls) << std::endl;
- {
- linestring_2d ls_copy;
- std::unique_copy(ls.begin(), ls.end(), std::back_inserter(ls_copy),
- boost::geometry::equal_to<point_2d>());
- ls = ls_copy;
- std::cout << "uniquecopy: " << dsv(ls) << std::endl;
- }
- // Lines can be simplified. This removes points, but preserves the shape
- linestring_2d ls_simplified;
- simplify(ls, ls_simplified, 0.5);
- std::cout << "simplified: " << dsv(ls_simplified) << std::endl;
- // for_each:
- // 1) Lines can be visited with std::for_each
- // 2) for_each_point is also defined for all geometries
- // 3) for_each_segment is defined for all geometries to all segments
- // 4) loop is defined for geometries to visit segments
- // with state apart, and to be able to break out (not shown here)
- {
- linestring_2d lscopy = ls;
- std::for_each(lscopy.begin(), lscopy.end(), translate_function<point_2d>);
- for_each_point(lscopy, scale_functor<point_2d>());
- for_each_point(lscopy, translate_function<point_2d>);
- std::cout << "modified line: " << dsv(lscopy) << std::endl;
- }
- // Lines can be clipped using a clipping box. Clipped lines are added to the output iterator
- box_2d cb(point_2d(1.5, 1.5), point_2d(4.5, 2.5));
- std::vector<linestring_2d> clipped;
- intersection(cb, ls, clipped);
- // Also possible: clip-output to a vector of vectors
- std::vector<std::vector<point_2d> > vector_out;
- intersection(cb, ls, vector_out);
- std::cout << "clipped output as vector:" << std::endl;
- for (std::vector<std::vector<point_2d> >::const_iterator it
- = vector_out.begin(); it != vector_out.end(); ++it)
- {
- std::cout << dsv(*it) << std::endl;
- }
- // Calculate the convex hull of the linestring
- model::polygon<point_2d> hull;
- convex_hull(ls, hull);
- std::cout << "Convex hull:" << dsv(hull) << std::endl;
- // All the above assumed 2D Cartesian linestrings. 3D is possible as well
- // Let's define a 3D point ourselves, this time using 'float'
- typedef model::point<float, 3, cs::cartesian> point_3d;
- model::linestring<point_3d> line3;
- line3.push_back(make<point_3d>(1,2,3));
- line3.push_back(make<point_3d>(4,5,6));
- line3.push_back(make<point_3d>(7,8,9));
- // Not all algorithms work on 3d lines. For example convex hull does NOT.
- // But, for example, length, distance, simplify, envelope and stream do.
- std::cout << "3D: length: " << length(line3) << " line: " << dsv(line3) << std::endl;
- // With DSV you can also use other delimiters, e.g. JSON style
- std::cout << "JSON: "
- << dsv(ls, ", ", "[", "]", ", ", "[ ", " ]")
- << std::endl;
- return 0;
- }
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