CGAL——学习2

#include <iostream>
#include <CGAL/Simple_cartesian.h>
typedef CGAL::Simple_cartesian<double> Kernel; //这个kernel 决定了点云的一些特性， 和精度 double。
typedef Kernel::Point_2 Point_2; //先记住这个形式！ 
typedef Kernel::Segment_2 Segment_2; //记住这个形式！
int main()
{
  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);//这个应该是边 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;
  std::cout << "p, q, and m ";
  switch (CGAL::orientation(p,q,m)){ //判断朝向。
  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;
  }
  std::cout << " midpoint(p,q) = " << CGAL::midpoint(p,q) << std::endl;
  return 0;
}