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cgal/Combinatorial_map/include/CGAL/Path_on_surface.h

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// Copyright (c) 2017 CNRS and LIRIS' Establishments (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 3 of the License,
// or (at your option) any later version.
//
// 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.
//
// $URL$
// $Id$
// SPDX-License-Identifier: LGPL-3.0+
//
// Author(s) : Guillaume Damiand <guillaume.damiand@liris.cnrs.fr>
//
#ifndef CGAL_PATH_ON_SURFACE_H
#define CGAL_PATH_ON_SURFACE_H 1
#include <stack>
#include <CGAL/Union_find.h>
#include <CGAL/Path_generators.h>
#include <boost/unordered_map.hpp>
namespace CGAL {
template<typename Map_>
class Path_on_surface
{
public:
typedef Map_ Map;
typedef typename Map::Dart_handle Dart_handle;
typedef typename Map::Dart_const_handle Dart_const_handle;
typedef Path_on_surface<Map> Self;
Path_on_surface(const Map& amap) : m_map(amap), m_is_closed(false)
{}
void swap(Self& p2)
{
assert(&m_map==&(p2.m_map));
m_path.swap(p2.m_path);
std::swap(m_is_closed, p2.m_is_closed);
}
// @return true iff the path is empty
bool is_empty() const
{ return m_path.empty(); }
std::size_t length() const
{ return m_path.size(); }
// @return true iff the path is closed (update after each path modification).
bool is_closed() const
{ return m_is_closed; }
const Map& get_map() const
{ return m_map; }
void clear()
{ m_path.clear(); }
std::size_t next_index(std::size_t i) const
{ return (is_closed() && i==m_path.size()-1?0:i+1); }
std::size_t prev_index(std::size_t i) const
{ return (is_closed() && i==0?m_path.size()-1:i-1); }
Dart_const_handle get_ith_dart(std::size_t i) const
{
assert(i<=m_path.size());
return m_path[(i==m_path.size()?0:i)];
}
Dart_const_handle operator[] (std::size_t i) const
{
assert(i<=m_path.size());
return m_path[((is_closed() && i==m_path.size())?0:i)];
}
Dart_const_handle back() const
{
assert(!is_empty());
return m_path.back();
}
void push_back(Dart_const_handle dh)
{
assert(dh!=NULL && dh!=m_map.null_dart_handle);
assert((is_empty() ||
CGAL::template belong_to_same_cell<Map, 0>
(m_map, m_map.other_extremity(back()), dh)));
m_path.push_back(dh);
update_is_closed();
}
// @return true iff the path is valid; i.e. a sequence of edges two by
// two adjacent.
bool is_valid() const
{
for (unsigned int i=1; i<m_path.size(); ++i)
{
if (m_path[i]==NULL || m_path[i]==m_map.null_dart_handle)
{ return false; }
Dart_const_handle pend=m_map.other_extremity(m_path[i-1]);
if (pend==Map::null_handle) { return false; }
if (!CGAL::template belong_to_same_cell<Map,0>(m_map, m_path[i], pend))
{ return false; }
}
if (is_closed())
{
Dart_const_handle pend=m_map.other_extremity(m_path[m_path.size()-1]);
if (pend==Map::null_handle) { return false; }
if (!CGAL::template belong_to_same_cell<Map,0>(m_map, pend, m_path[0]))
{ return false; }
}
return true;
}
// Update m_is_closed to true iff the path is closed (i.e. the second
// extremity of the last dart of the path is the same vertex than the one
// of the first dart of the path).
void update_is_closed()
{
if (is_empty()) { m_is_closed=false; } // or true by vacuity ?
if (!is_valid()) { m_is_closed=false; } // Interest ??
Dart_const_handle pend=m_map.other_extremity(back());
if (pend==Map::null_handle) { m_is_closed=false; }
m_is_closed=CGAL::belong_to_same_cell<Map,0>(m_map, m_path[0], pend);
}
// @return true iff the path does not pass twice through a same edge
// or a same vertex.
bool is_simple() const
{
typename Map::size_type markvertex=m_map.get_new_mark();
typename Map::size_type markedge=m_map.get_new_mark();
bool res=true;
unsigned int i=0;
for (i=0; res && i<m_path.size(); ++i)
{
if (m_map.is_marked(m_path[i], markvertex)) res=false;
if (m_map.is_marked(m_path[i], markedge)) res=false;
CGAL::mark_cell<Map, 0>(m_path[i], markvertex);
CGAL::mark_cell<Map, 1>(m_path[i], markedge);
}
i=0;
while(m_map.number_of_marked_darts(markedge)>0)
{
assert(i<m_path.size());
CGAL::unmark_cell<Map, 0>(m_path[i], markvertex);
CGAL::unmark_cell<Map, 1>(m_path[i], markedge);
++i;
}
m_map.free_mark(markvertex);
m_map.free_mark(markedge);
return res;
}
/// @return the turn between dart number i and dart number i+1.
/// (turn is position of the second edge in the cyclic ordering of
/// edges starting from the first edge around the second extremity
/// of the first dart)
std::size_t next_turn(std::size_t i) const
{
assert(is_valid());
assert(i<m_path.size());
if (!is_closed() && i==length()-1)
{ return 0; }
Dart_const_handle d1=m_path[i];
Dart_const_handle d2=get_ith_dart(i+1); // Work also for the last dart for cycles
assert(d1!=d2);
std::size_t res=1;
while (m_map.template beta<1>(d1)!=d2)
{
++res;
d1=m_map.template beta<1, 2>(d1);
}
// std::cout<<"next_turn="<<res<<std::endl;
return res;
}
/// Same than next_turn but turning in reverse orientation around vertex.
std::size_t next_negative_turn(std::size_t i) const
{
assert(is_valid());
assert(i<m_path.size());
if (!is_closed() && i==length()-1)
{ return 0; }
Dart_const_handle d1=m_map.template beta<2>(m_path[i]);
Dart_const_handle d2=m_map.template beta<2>(get_ith_dart(i+1)); // Work also for the last dart for cycles
assert(d1!=d2);
std::size_t res=1;
while (m_map.template beta<0>(d1)!=d2)
{
++res;
d1=m_map.template beta<0, 2>(d1);
}
// std::cout<<"next_negative_turn="<<res<<std::endl;
return res;
}
std::size_t find_end_of_braket(std::size_t begin, bool positive) const
{
assert((positive && next_turn(begin)==1) ||
(!positive && next_negative_turn(begin)==1));
std::size_t end=begin+1;
if (!is_closed() && end==length()-1)
{ return begin; } // begin is the before last dart
while ((positive && next_turn(end)==2) ||
(!positive && next_negative_turn(end)==2))
{ end=next_index(end); }
if ((positive && next_turn(end)==1) ||
(!positive && next_negative_turn(end)==1)) // We are on the end of a bracket
{ end=next_index(end); }
else
{ end=begin; }
return end;
}
void transform_positive_bracket(std::size_t begin, std::size_t end,
Self& new_path)
{
// There is a special case for (1 2^r). In this case, we need to ignore
// the two darts begin and end
Dart_const_handle d1=(next_index(begin)!=end?
m_map.template beta<0>(get_ith_dart(begin)):
m_map.template beta<1,2,0>(get_ith_dart(end)));
Dart_const_handle d2=(next_index(begin)!=end?
m_map.template beta<2,0,2>(get_ith_dart(end)):
m_map.template beta<0,0,2>(get_ith_dart(begin)));
new_path.push_back(m_map.template beta<2>(d1));
CGAL::extend_straight_negative_until(new_path, d2);
}
void transform_negative_bracket(std::size_t begin, std::size_t end,
Self& new_path)
{
// There is a special case for (-1 -2^r). In this case, we need to ignore
// the two darts begin and end
Dart_const_handle d1=(next_index(begin)!=end?
m_map.template beta<2,1>(get_ith_dart(begin)):
m_map.template beta<2,0,2,1>(get_ith_dart(end)));
Dart_const_handle d2=(next_index(begin)!=end?
m_map.template beta<1>(get_ith_dart(end)):
m_map.template beta<2,1,1>(get_ith_dart(begin)));
new_path.push_back(d1);
CGAL::extend_straight_positive_until(new_path, d2);
}
void transform_bracket(std::size_t begin, std::size_t end,
Self& new_path,
bool positive)
{
if (positive)
{ transform_positive_bracket(begin, end, new_path); }
else
{ transform_negative_bracket(begin, end, new_path); }
}
// copy all darts starting from begin and going to the dart before end
// from this path to new_path.
void copy_rest_of_path(std::size_t begin, std::size_t end,
Self& new_path)
{
assert(end<=length());
assert(begin<=end);
while(begin!=end)
{
new_path.push_back(get_ith_dart(begin));
++begin;
}
}
bool bracket_flattening_one_step()
{
if (is_empty()) return false;
Self new_path(m_map);
bool positive=false;
std::size_t begin, end;
std::size_t lastturn=m_path.size()-(is_closed()?0:1);
for (begin=0; begin<lastturn; ++begin)
{
positive=(next_turn(begin)==1);
if (positive || next_negative_turn(begin)==1)
{
// we test if begin is the beginning of a bracket
end=find_end_of_braket(begin, positive);
if (begin!=end)
{
/* std::cout<<"Bracket: ["<<begin<<"; "<<end<<"] "
<<(positive?"+":"-")<<std::endl; */
if (end<begin)
{
if (!is_closed())
{ return false; }
copy_rest_of_path(end+1, begin, new_path);
}
else if (next_index(begin)!=end) // Special case of (1 2^r)
{ copy_rest_of_path(0, begin, new_path); }
transform_bracket(begin, end, new_path, positive);
if (begin<end && next_index(begin)!=end && end<length()-1)
{ copy_rest_of_path(end+1, length(), new_path); }
swap(new_path);
return true;
}
}
}
return false;
}
// Simplify the path by removing all brackets
bool bracket_flattening()
{
bool res=false;
while(bracket_flattening_one_step())
{ res=true; }
return res;
}
bool remove_spurs_one_step()
{
if (is_empty()) return false;
bool res=false;
std::size_t i;
std::size_t lastturn=m_path.size()-(is_closed()?0:1);
Self new_path(m_map);
for (i=0; i<lastturn; )
{
if (m_path[i]==m_map.template beta<2>(m_path[next_index(i)]))
{
i+=2;
res=true;
}
else
{
new_path.push_back(m_path[i]); // We copy this dart
++i;
}
}
if (i==m_path.size()-1)
{ new_path.push_back(m_path[m_path.size()-1]); } // we copy the last dart
swap(new_path);
return res;
}
// Simplify the path by removing all spurs
bool remove_spurs()
{
bool res=false;
while(remove_spurs_one_step())
{ res=true; }
return res;
}
// Simplify the path by removing all possible brackets and spurs
void simplify()
{
bool modified=false;
do
{
modified=bracket_flattening_one_step();
if (!modified)
{ modified=remove_spurs_one_step(); }
}
while(modified);
}
bool find_l_shape(std::size_t begin,
std::size_t& middle,
std::size_t& end) const
{
assert(next_negative_turn(begin)==1 || next_negative_turn(begin)==2);
end=begin+1;
if (end==m_path.size()-1 && !is_closed())
{ return false; } // begin is the before last dart
while (next_negative_turn(end)==2 && end!=begin)
{ end=next_index(end); }
if (begin==end)
{ // Case of a path having only 2 turns
return true;
}
if (next_negative_turn(end)==1)
{
middle=end;
end=next_index(end);
}
else
{ return false; }
while (next_negative_turn(end)==2 && end!=begin)
{ end=next_index(end); }
return true;
}
void push_l_shape(std::size_t begin,
std::size_t middle,
std::size_t end,
Self& new_path)
{
assert(begin!=middle);
assert(middle!=end);
Dart_const_handle d1=
m_map.template beta<2,1>(get_ith_dart(begin));
new_path.push_back(d1);
CGAL::extend_uturn_positive(new_path, 1);
d1=m_map.template beta<2,1,1>(get_ith_dart(middle));
CGAL::extend_straight_positive_until(new_path, d1);
CGAL::extend_uturn_positive(new_path, 3);
d1=m_map.template beta<2,0,2,1>(get_ith_dart(end));
CGAL::extend_straight_positive_until(new_path, d1);
CGAL::extend_uturn_positive(new_path, 1);
}
void push_l_shape_cycle_2()
{
Dart_const_handle d1=
m_map.template beta<2,1,1>(get_ith_dart(0));
clear();
push_back(d1);
CGAL::extend_straight_positive_until(*this, d1);
}
bool right_push_one_step()
{
std::size_t begin, middle, end;
std::size_t lastturn=m_path.size()-(is_closed()?0:1);
std::size_t next_turn, next_next_turn;
bool prev2=false;
for (middle=0; middle<lastturn; ++middle)
{
next_turn=next_negative_turn(middle);
if (next_turn==2)
{
if (!prev2)
{
begin=middle; // First 2 of a serie
prev2=true;
if (begin==0 && is_closed())
{
begin=length()-1;
do
{
next_turn=next_negative_turn(begin);
if (next_turn==2) { --begin; }
if (begin==0) // Loop of only -2 turns
{
push_l_shape_cycle_2();
return true;
}
}
while(next_turn==2);
}
// Here begin is the first dart of the path s.t. next_turn==-2
// i.e. the previous turn != -2
}
}
else
{
prev2=false;
if (next_turn==1)
{ // Here middle is a real middle; we already know begin (or we know
// that there is no -2 before if !prev2), we only need to compute
// end.
end=next_index(middle);
do
{
next_turn=next_negative_turn(end);
if (next_turn==2) { end=next_index(end); }
assert(end!=middle);
}
while(next_turn==2);
// And here now we can push
Self new_path(m_map);
if (end<begin)
{
if (!is_closed())
{ return false; }
copy_rest_of_path(end+1, begin, new_path);
}
else // TODO SPECIAL CASES ??
{ copy_rest_of_path(0, begin, new_path); }
push_l_shape(begin, middle, end, new_path);
if (begin<end /* && XXX (TODO SPECIAL CASES ??)*/)
{ copy_rest_of_path(end+1, length(), new_path); }
swap(new_path);
return true;
}
}
}
return false;
}
bool right_push()
{
bool res=false;
while(right_push_one_step())
{ res=true; }
return res;
}
void display_positive_turns() const
{
std::cout<<"(";
if (!is_empty())
{
std::size_t i;
for (i=0; i<m_path.size()-1; ++i)
{
if (m_path[i]==m_map.template beta<2>(m_path[i+1]))
{ std::cout<<"0 "; }
else { std::cout<<next_turn(i)<<" "; }
}
if (is_closed())
{
if (m_path[i]==m_map.template beta<2>(m_path[0]))
{ std::cout<<"0 "; }
else { std::cout<<next_turn(i)<<" "; }
}
}
std::cout<<")";
}
void display_negative_turns() const
{
std::cout<<"(";
if (!is_empty())
{
std::size_t i;
for (i=0; i<m_path.size()-1; ++i)
{
if (m_path[i]==m_map.template beta<2>(m_path[i+1]))
{ std::cout<<"0 "; }
else { std::cout<<"-"<<next_negative_turn(i)<<" "; }
}
if (is_closed())
{
if (m_path[i]==m_map.template beta<2>(m_path[0]))
{ std::cout<<"0 "; }
else { std::cout<<"-"<<next_negative_turn(i)<<" "; }
}
}
std::cout<<")";
}
void reverse()
{
std::vector<Dart_const_handle> new_path(m_path.size());
for (std::size_t i=0; i<m_path.size(); ++i)
{
new_path[m_path.size()-1-i]=m_map.template beta<2>(m_path[i]);
}
new_path.swap(m_path);
}
protected:
const Map& m_map; // The underlying map
std::vector<Dart_const_handle> m_path; // The sequence of darts
bool m_is_closed; // True iff the path is a cycle
};
} // namespace CGAL
#endif // CGAL_PATH_ON_SURFACE_H //
// EOF //
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