GEOS에서 사각형을 만드는 방법은 무엇입니까?

Question

GEOS 라이브러리의 C++ API를 사용하여 사각형을 만드는 방법은 무엇입니까?

Answer 1

다음 구현은 GEOS에서 작업을 완료합니다. 다음과 같이

//Compile with: g++ code.cpp -lgeos 
#include <geos/geom/Polygon.h> 
#include <geos/geom/LinearRing.h> 
#include <geos/geom/CoordinateSequenceFactory.h> 
#include <geos/geom/GeometryFactory.h> 
#include <iostream> 

geos::geom::Polygon* MakeBox(double xmin, double ymin, double xmax, double ymax){ 
    geos::geom::GeometryFactory factory; 
    geos::geom::CoordinateSequence* temp = factory.getCoordinateSequenceFactory()->create((std::size_t) 0, 0); 

    temp->add(geos::geom::Coordinate(xmin, ymin)); 
    temp->add(geos::geom::Coordinate(xmin, ymax)); 
    temp->add(geos::geom::Coordinate(xmax, ymax)); 
    temp->add(geos::geom::Coordinate(xmax, ymin)); 
    //Must close the linear ring or we will get an error: 
    //"Points of LinearRing do not form a closed linestring" 
    temp->add(geos::geom::Coordinate(xmin, ymin)); 

    geos::geom::LinearRing *shell=factory.createLinearRing(temp); 

    //NULL in this case could instead be a collection of one or more holes 
    //in the interior of the polygon 
    return factory.createPolygon(shell,NULL); 
} 

int main(){ 
    geos::geom::Polygon* box = MakeBox(0,0,10,10); 
    std::cout<<box->getArea()<<std::endl; 
} 

참고로

---

, 당신은 또한 boost::polygon 라이브러리를 사용하여이 작업을 수행 할 수 있습니다.

//Compile with: g++ code.cpp 
#include <boost/polygon/polygon.hpp> 
#include <iostream> 
namespace gtl = boost::polygon; 

typedef gtl::polygon_data<float> Polygon; 

Polygon MakeBox(float xmin, float ymin, float xmax, float ymax){ 
    typedef gtl::polygon_traits<Polygon>::point_type Point; 
    Point pts[] = { 
    gtl::construct<Point>(xmin, ymin), 
    gtl::construct<Point>(xmin, ymax), 
    gtl::construct<Point>(xmax, ymax), 
    gtl::construct<Point>(xmax, ymin) 
    }; 
    Polygon poly; 
    gtl::set_points(poly, pts, pts+4); 

    return poly; 
} 

int main(){ 
    Polygon box = MakeBox(0,0,10,10); 
    std::cout<<gtl::area(box)<<std::endl; 
} 

---

또한 Clipper와

. Clipper는 부동 소수점 좌표를 사용할 수 없습니다.

#include "clipper_cpp/clipper.hpp" 
#include <iostream> 

ClipperLib::Paths MakeBox(int xmin, int ymin, int xmax, int ymax){ 
    ClipperLib::Paths box(1); 
    //Note that we run the path in the reverse direction to previous examples in 
    //order to maintain positive area 
    box[0] << ClipperLib::IntPoint(xmin,ymin) << ClipperLib::IntPoint(xmax,ymin) 
     << ClipperLib::IntPoint(xmax,ymax) << ClipperLib::IntPoint(xmin,ymax); 
    return box; 
} 

int main(){ 
    ClipperLib::Paths box = MakeBox(0,0,10,10); 
    std::cout<<ClipperLib::Area(box[0])<<std::endl; 
}