升压几何笛卡尔2 .hpp

教程太老了。自从那篇教程写完之后，情况发生了很大的变化。

无论如何，我已经修改了上面链接中的代码，以便它可以在Boost ver 1.53.0中编译…

#include <boost/geometry.hpp>
#include <boost/geometry/geometries/point_xy.hpp>
#include <boost/geometry/geometries/polygon.hpp>
#include <boost/geometry/io/wkt/wkt.hpp>
#include <boost/geometry/multi/geometries/multi_polygon.hpp>
using namespace boost::geometry;
typedef model::d2::point_xy<double> point;
typedef model::ring< point > ring;
typedef model::polygon< point > polygon;
typedef model::multi_polygon< polygon > polygons;
typedef model::box< point > box;

// Define a polygon and fill the outer ring.
// In most cases you will read it from a file or database
polygon poly;
{
  read_wkt("POLYGON((2.0 1.3, 2.4 1.7, 2.8 1.8, 3.4 1.2, 3.7 1.6, 
        3.4 2.0, 4.1 3.0, 5.3 2.6, 5.4 1.2, 4.9 0.8, 2.9 0.7, 
        2.0 1.3))", poly);
}
// Polygons should be closed, and directed clockwise. If you're not sure if that is the case,
// call the correct algorithm
correct(poly);
// Polygons can be streamed as text
// (or more precisely: as DSV (delimiter separated values))
std::cout << dsv(poly) << std::endl;
// As with lines, bounding box of polygons can be calculated
box b;
envelope(poly, b);
std::cout << dsv(b) << std::endl;
// The area of the polygon can be calulated
std::cout << "area: " << area(poly) << std::endl;
// And the centroid, which is the center of gravity
point cent;
centroid(poly, cent);
std::cout << "centroid: " << dsv(cent) << std::endl;

// The number of points have to called per ring separately
std::cout << "number of points in outer ring: " << poly.outer().size() << std::endl;
// Polygons can have one or more inner rings, also called holes, donuts, islands, interior rings.
// Let's add one
{
    poly.inners().resize(1);
    ring& inner = poly.inners().back();
    read_wkt("POLYGON((4.0 2.0, 4.2 1.4, 4.8 1.9, 4.4 2.2, 4.0 2.0))", inner);
}
correct(poly);
std::cout << "with inner ring:" << dsv(poly) << std::endl;
// The area of the polygon is changed of course
std::cout << "new area of polygon: " << area(poly) << std::endl;
centroid(poly, cent);
std::cout << "new centroid: " << dsv(cent) << std::endl;
// You can test whether points are within a polygon
std::cout << "point in polygon:"
    << " p1: "  << (within(make<point>(3.0, 2.0), poly)?"true":"false")
    << " p2: "  << (within(make<point>(3.7, 2.0), poly)?"true":"false")
    << " p3: "  << (within(make<point>(4.4, 2.0), poly)?"true":"false")
    << std::endl;
// As with linestrings and points, you can derive from polygon to add, for example,
// fill color and stroke color. Or SRID (spatial reference ID). Or Z-value. Or a property map.
// We don't show this here.
// Clip the polygon using a bounding box
box cb(make<point>(1.5, 1.5), make<point>(4.5, 2.5));
polygons v;
intersection(cb, poly, v);
std::cout << "Clipped output polygons" << std::endl;
for (polygons::const_iterator it = v.begin(); it != v.end(); ++it)
{
    std::cout << dsv(*it) << std::endl;
}
union_(cb, poly, v);
polygon hull;
convex_hull(poly, hull);
std::cout << "Convex hull:" << dsv(hull) << std::endl;
// If you really want:
//   You don't have to use a vector, you can define a polygon with a deque
//   You can specify the container for the points and for the inner rings independently
typedef model::polygon<point, true, true, std::vector, std::deque> polygon_deq;
polygon_deq poly2;
polygon_deq::ring_type& r = poly2.outer();
append(r, make<point>(2.8, 1.9));
append(r, make<point>(2.9, 2.4));
append(r, make<point>(3.3, 2.2));
append(r, make<point>(3.2, 1.8));
append(r, make<point>(2.8, 1.9));
std::cout << dsv(poly2) << std::endl;