sweep_line_functors.h

来自「CGAL is a collaborative effort of severa」· C头文件 代码 · 共 150 行

// Copyright (c) 1997  Tel-Aviv University (Israel).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you may redistribute it under
// the terms of the Q Public License version 1.0.
// See the file LICENSE.QPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $Source: /CVSROOT/CGAL/Packages/Sweep_line_2/include/CGAL/Sweep_line_2/Sweep_line_functors.h,v $
// $Revision: 1.18 $ $Date: 2004/10/21 13:43:47 $
// $Name:  $
//
// Author(s)     : Tali Zvi <[e-mail]>

#ifndef CGAL_SWEEP_LINE_FUNCTORS_H
#define CGAL_SWEEP_LINE_FUNCTORS_H

CGAL_BEGIN_NAMESPACE

template <class Point, class SweepLineTraits_2> class Point_less_functor 
{
public:
  typedef SweepLineTraits_2 Traits;
  
  Point_less_functor(Traits * traits) : m_traits(traits) {}
  
  bool operator()(const Point * p1, const Point * p2) const 
  { 
    return (m_traits->compare_xy(*p1,*p2) == SMALLER);
  }

	 bool operator()( const Point& p1,const   Point& p2) const 
  { 
    return (m_traits->compare_xy(p1,p2) == SMALLER);
  }

private:
  /*! a pointer to a traits class */
  Traits * m_traits;
};




template <class SweepLineTraits_2, class Subcurve>
class Status_line_curve_less_functor 
{
public:
  typedef SweepLineTraits_2 Traits;
  typedef typename Traits::Point_2 Point_2;
  typedef typename Traits::X_monotone_curve_2 X_monotone_curve_2;
  typedef bool (Status_line_curve_less_functor::*func)
    (const Subcurve*, const Subcurve*) const;

  struct Compare_param {
    Compare_param(Traits *t) : m_compare_func(1), m_traits(t)  {}
    int m_compare_func;
    Traits * m_traits;
  };

  Status_line_curve_less_functor(Compare_param *p) : m_compare_param(p) {
    m_compare[0] = &Status_line_curve_less_functor::compare_at;
    m_compare[1] = &Status_line_curve_less_functor::compare_right;
  }

  bool operator()(const Subcurve * c1, const Subcurve * c2) const {
    return (this->*m_compare[m_compare_param->m_compare_func])(c1, c2);
  }

  bool compare_at(const Subcurve * c1, const Subcurve * c2)  const 
  {
    const Point_2 * p = &(c2->get_last_point());
    if ( m_compare_param->m_traits->compare_x(c1->get_last_point(),  
					      c2->get_last_point()) == LARGER )
      p = &(c1->get_last_point());

    Comparison_result r = 
      m_compare_param->m_traits->curves_compare_y_at_x(c1->get_curve(), 
    				   c2->get_curve(), 
    				   *p);
    if ( r == SMALLER) {
      return true;
    } 
    return false;
  }

  bool compare_right(const Subcurve * c1, const Subcurve * c2)  const 
  {
    const X_monotone_curve_2 &cv1 = c1->get_curve();
    const X_monotone_curve_2 &cv2 = c2->get_curve();
    Traits *t = m_compare_param->m_traits;
    if ( t->curve_is_vertical(cv1) )
    {
      if (t->point_in_x_range(cv2, c1->get_source()) &&
	  t->curve_compare_y_at_x(c1->get_top_end(), cv2) == SMALLER )
      {
	return true;
      }
      return false;
    }
    if ( t->curve_is_vertical(cv2))
    {
      if (t->point_in_x_range(cv1, c2->get_source()) &&
	  t->curve_compare_y_at_x(c2->get_bottom_end(), cv1) == LARGER)
      {
	return true;
      }
      return false;
    }

    const Point_2 *p = &(c2->get_last_point());
    if ( m_compare_param->m_traits->compare_x(c1->get_last_point(),  
					      c2->get_last_point()) == LARGER )
      p = &c1->get_last_point();

    // non of the curves is vertical... 
    Comparison_result r =  t->curves_compare_y_at_x (c1->get_curve(), 
						     c2->get_curve(), 
						     *p);

    if (r == EQUAL)
      r = t->curves_compare_y_at_x_right(c1->get_curve(), 
					 c2->get_curve(), 
					 *p);
    if ( r == SMALLER) {
      return true;
    } 
    if ( r == LARGER ) {
      return false;
    }

    // r = EQUAL
    return ( c1->getId() < c2->getId() );
  }

  Compare_param * m_compare_param;

private:
  func m_compare[2];
};

CGAL_END_NAMESPACE

#endif