cgal demo

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已于 2023-06-23 23:33:06 修改

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分类专栏： Cgal 文章标签： c++ 算法开发语言

于 2023-06-23 09:33:22 首次发布

本文链接：https://blog.youkuaiyun.com/vv1025/article/details/131347692

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该代码示例展示了使用CGAL库进行精确几何计算，包括点、线段和直线的构造、距离计算以及交点检测。在处理交点时，出现了结果在不同环境中输出不一致的问题，特别是涉及到浮点数精度时。代码中尝试使用精确构造内核来解决精度不足的问题。

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#include <iostream>
#include <CGAL/Simple_cartesian.h>
typedef CGAL::Simple_cartesian<double> Kernel;
typedef Kernel::Point_2 Point_2;
typedef Kernel::Segment_2 Segment_2;
//#pragma comment(lib, "gmp.dll")
#include <iostream>

#include "gmp.h"

#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/intersections.h>
typedef CGAL::Exact_predicates_exact_constructions_kernel K;
typedef K::Point_2 Point_21;
typedef K::Line_2 Line_2;
typedef K::Intersect_2 Intersect_2;
using namespace std;
int main()
{
    std::cout << "Hello World!\n";
    //std::cout << __cplusplus << _MSVC_LANG << BOOST_MSVC << std::endl;
    Point_2 p(1, 1), q(10, 10);
    std::cout << "p = " << p << std::endl;
    std::cout << "q = " << q.x() << " " << q.y() << std::endl;
    std::cout << "sqdist(p,q) = "
        << CGAL::squared_distance(p, q) << std::endl;
    Segment_2 s(p, q);
    Point_2 m(5, 9);
    std::cout << "m = " << m << std::endl;
    std::cout << "sqdist(Segment_2(p,q), m) = "
        << CGAL::squared_distance(s, m) << std::endl << __cplusplus << std::endl;
    std::cout << "p, q, and m ";
    switch (CGAL::orientation(p, q, m)) {
    case CGAL::COLLINEAR:
        std::cout << "are collinear\n";
        break;
    case CGAL::LEFT_TURN:
        std::cout << "make a left turn\n";
        break;
    case CGAL::RIGHT_TURN:
        std::cout << "make a right turn\n";
        break;
    }

    Line_2 lina(1, 1, 2);
    Line_2 linb(1, -1, 1);
    CGAL::cpp11::result_of<Intersect_2(Line_2, Line_2)>::type
        result = intersection(lina, linb);
    if (result)
    {
        const Point_21* p = boost::get<Point_21 >(&*result);
        std::cout << "ok\n";
        //std::cout << "q = " << p->x() << " " << p->y() << std::endl;
        //std::cout << *p << std::endl;
        std::cout << p->x() << ", " << p->y() << std::endl;
    }
    system("pause");
    
    
    return 0;
}

出现的问题

if (result)
    {
        const Point_21* p = boost::get<Point_21 >(&*result);
        std::cout << "ok\n";
        //std::cout << "q = " << p->x() << " " << p->y() << std::endl;
        //std::cout << *p << std::endl;
        std::cout << p->x() << ", " << p->y() << std::endl;
        acutPrintf(_T("\n%f %f"), p->x(),p->y() );
    }