/* This file is part of the Gudhi Library. The Gudhi library
* (Geometric Understanding in Higher Dimensions) is a generic C++
* library for computational topology.
*
* Author(s): David Salinas
*
* Copyright (C) 2014 INRIA Sophia Antipolis-Mediterranee (France)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*/
#ifndef SKELETON_BLOCKER_CONTRACTOR_H_
#define SKELETON_BLOCKER_CONTRACTOR_H_
// todo remove the queue to be independent from cgald
#include
#include
#include
#include
#include
#include
#include
#include // xxx remove
#include // xxx remove
#include
#include
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#include
#include
#include // for pair
#include
namespace Gudhi {
namespace contraction {
template
Placement_policy* make_first_vertex_placement() {
return new First_vertex_placement();
}
template
Valid_contraction_policy* make_link_valid_contraction() {
return new Link_condition_valid_contraction();
}
/**
*@brief Visitor to remove popable blockers after an edge contraction.
*/
template
class Contraction_visitor_remove_popable : public Contraction_visitor {
public:
typedef typename Profile::Point Point;
typedef typename Profile::Complex Complex;
typedef typename Complex::Vertex_handle Vertex_handle;
void on_contracted(const Profile &profile, boost::optional< Point > placement) override {
profile.complex().remove_all_popable_blockers(profile.v0_handle());
}
};
template
Contraction_visitor* make_remove_popable_blockers_visitor() {
return new Contraction_visitor_remove_popable();
}
/**
*@class Skeleton_blocker_contractor
*@brief Class that allows to contract iteratively edges of a simplicial complex.
*@ingroup contr
*
* @details The simplification algorithm consists in iteratively picking the
* edge with lowest cost and performing an edge contraction if the contraction is valid.
* This class is policy based (and much inspired from the edge collapse package of CGAL http://doc.cgal.org/latest/Surface_mesh_simplification/index.html).
*
* Policies that can be changed are :
* - the cost policy : how much cost an edge contraction
* - the placement policy : where will be placed the contraction point
* - the valid contraction policy : is the contraction valid. For instance, it can be
* a topological condition (link condition) or a geometrical condition (normals messed up).
*
*/
template>
class Skeleton_blocker_contractor : private skeleton_blocker::Dummy_complex_visitor<
typename GeometricSimplifiableComplex::Vertex_handle> {
GeometricSimplifiableComplex& complex_;
public:
typedef typename GeometricSimplifiableComplex::Graph_vertex Graph_vertex;
typedef typename GeometricSimplifiableComplex::Vertex_handle Vertex_handle;
typedef typename GeometricSimplifiableComplex::Simplex Simplex;
typedef typename GeometricSimplifiableComplex::Root_vertex_handle Root_vertex_handle;
typedef typename GeometricSimplifiableComplex::Graph_edge Graph_edge;
typedef typename GeometricSimplifiableComplex::Edge_handle Edge_handle;
typedef typename GeometricSimplifiableComplex::Point Point;
typedef EdgeProfile Profile;
typedef Cost_policy Cost_policy_;
typedef Placement_policy Placement_policy_;
typedef Valid_contraction_policy Valid_contraction_policy_;
typedef Contraction_visitor Contraction_visitor_;
typedef Edge_profile_factory Edge_profile_factory_;
typedef boost::optional Cost_type;
typedef boost::optional Placement_type;
typedef size_t size_type;
typedef Skeleton_blocker_contractor Self;
private:
struct Compare_id {
Compare_id() : algorithm_(0) { }
Compare_id(Self const* aAlgorithm) : algorithm_(aAlgorithm) { }
bool operator()(Edge_handle a, Edge_handle b) const {
return algorithm_->get_undirected_edge_id(a) < algorithm_->get_undirected_edge_id(b);
}
Self const* algorithm_;
};
struct Compare_cost {
Compare_cost() : algorithm_(0) { }
Compare_cost(Self const* aAlgorithm) : algorithm_(aAlgorithm) { }
bool operator()(Edge_handle a, Edge_handle b) const {
// NOTE: A cost is an optional<> value.
// Absent optionals are ordered first; that is, "none < T" and "T > none" for any defined T != none.
// In consequence, edges with undefined costs will be promoted to the top of the priority queue and popped out
// first.
return algorithm_->get_data(a).cost() < algorithm_->get_data(b).cost();
}
Self const* algorithm_;
};
struct Undirected_edge_id : boost::put_get_helper {
typedef boost::readable_property_map_tag category;
typedef size_type value_type;
typedef size_type reference;
typedef Edge_handle key_type;
Undirected_edge_id() : algorithm_(0) { }
Undirected_edge_id(Self const* aAlgorithm) : algorithm_(aAlgorithm) { }
size_type operator[](Edge_handle e) const {
return algorithm_->get_undirected_edge_id(e);
}
Self const* algorithm_;
};
typedef CGAL::Modifiable_priority_queue PQ;
typedef typename PQ::handle pq_handle;
// An Edge_data is associated with EVERY edge in the complex (collapsible or not).
// It relates the edge with the PQ-handle needed to update the priority queue
// It also relates the edge with a policy-based cache
class Edge_data {
public:
Edge_data() : PQHandle_(), cost_() { }
Cost_type const& cost() const {
return cost_;
}
Cost_type & cost() {
return cost_;
}
pq_handle PQ_handle() const {
return PQHandle_;
}
bool is_in_PQ() const {
return PQHandle_ != PQ::null_handle();
}
void set_PQ_handle(pq_handle h) {
PQHandle_ = h;
}
void reset_PQ_handle() {
PQHandle_ = PQ::null_handle();
}
private:
pq_handle PQHandle_;
Cost_type cost_;
};
typedef Edge_data* Edge_data_ptr;
typedef boost::scoped_array Edge_data_array;
int get_undirected_edge_id(Edge_handle edge) const {
return complex_[edge].index();
}
const Edge_data& get_data(Edge_handle edge) const {
return edge_data_array_[get_undirected_edge_id(edge)];
}
Edge_data& get_data(Edge_handle edge) {
return edge_data_array_[get_undirected_edge_id(edge)];
}
Cost_type get_cost(const Profile & profile) const {
return (*cost_policy_)(profile, get_placement(profile));
}
Profile create_profile(Edge_handle edge) const {
if (edge_profile_factory_)
return edge_profile_factory_->make_profile(complex_, edge);
else
return Profile(complex_, edge);
}
void insert_in_PQ(Edge_handle edge, Edge_data& data) {
data.set_PQ_handle(heap_PQ_->push(edge));
++current_num_edges_heap_;
}
void update_in_PQ(Edge_handle edge, Edge_data& data) {
data.set_PQ_handle(heap_PQ_->update(edge, data.PQ_handle()));
}
void remove_from_PQ(Edge_handle edge, Edge_data& data) {
data.set_PQ_handle(heap_PQ_->erase(edge, data.PQ_handle()));
--current_num_edges_heap_;
}
boost::optional pop_from_PQ() {
boost::optional edge = heap_PQ_->extract_top();
if (edge)
get_data(*edge).reset_PQ_handle();
return edge;
}
private:
/**
* @brief Collect edges.
*
* Iterates over all edges of the simplicial complex and
* 1) inserts them in the priority queue sorted according to the Cost policy.
* 2) set the id() field of each edge
*/
void collect_edges() {
//
// Loop over all the edges in the complex in the heap
//
size_type size = complex_.num_edges();
DBG("Collecting edges ...");
DBGMSG("num edges :", size);
edge_data_array_.reset(new Edge_data[size]);
heap_PQ_.reset(new PQ(size, Compare_cost(this), Undirected_edge_id(this)));
std::size_t id = 0;
// xxx do a parralel for
for (auto edge : complex_.edge_range()) {
complex_[edge].index() = id++;
Profile const& profile = create_profile(edge);
Edge_data& data = get_data(edge);
data.cost() = get_cost(profile);
++initial_num_edges_heap_;
insert_in_PQ(edge, data);
if (contraction_visitor_) contraction_visitor_->on_collected(profile, data.cost());
}
DBG("Edges collected.");
}
bool should_stop(double lCost, const Profile &profile) const {
return false;
}
boost::optional get_placement(const Profile& profile) const {
return (*placement_policy_)(profile);
}
bool is_contraction_valid(Profile const& profile, Placement_type placement) const {
if (!valid_contraction_policy_) return true;
return (*valid_contraction_policy_)(profile, placement);
}
public:
/**
* \brief Contract edges.
*
* While the heap is not empty, it extracts the edge with the minimum
* cost in the heap then try to contract it.
* It stops when the Stop policy says so or when the number of contractions
* given by 'num_max_contractions' is reached (if this number is positive).
*/
void contract_edges(int num_max_contractions = -1) {
DBG("\n\nContract edges");
int num_contraction = 0;
bool unspecified_num_contractions = (num_max_contractions == -1);
//
// Pops and processes each edge from the PQ
//
boost::optional edge;
while ((edge = pop_from_PQ()) && ((num_contraction < num_max_contractions) || (unspecified_num_contractions))) {
Profile const& profile = create_profile(*edge);
Cost_type cost(get_data(*edge).cost());
if (contraction_visitor_) contraction_visitor_->on_selected(profile, cost, 0, 0);
DBGMSG("\n\n---- Pop edge - num vertices :", complex_.num_vertices());
if (cost) {
DBGMSG("sqrt(cost):", std::sqrt(*cost));
if (should_stop(*cost, profile)) {
if (contraction_visitor_) contraction_visitor_->on_stop_condition_reached();
DBG("should_stop");
break;
}
Placement_type placement = get_placement(profile);
if (is_contraction_valid(profile, placement) && placement) {
DBG("contraction_valid");
contract_edge(profile, placement);
++num_contraction;
} else {
DBG("contraction not valid");
if (contraction_visitor_) contraction_visitor_->on_non_valid(profile);
}
} else {
DBG("uncomputable cost");
}
}
if (contraction_visitor_) contraction_visitor_->on_stop_condition_reached();
}
bool is_in_heap(Edge_handle edge) const {
if (heap_PQ_->empty()) {
return false;
} else {
return edge_data_array_[get_undirected_edge_id(edge)].is_in_PQ();
}
}
bool is_heap_empty() const {
return heap_PQ_->empty();
}
/**
* @brief Returns an Edge_handle and a Placement_type. This pair consists in
* the edge with the lowest cost in the heap together with its placement.
* The returned value is initialized iff the heap is non-empty.
*/
boost::optional > top_edge() {
boost::optional > res;
if (!heap_PQ_->empty()) {
auto edge = heap_PQ_->top();
Profile const& profile = create_profile(edge);
Placement_type placement = get_placement(profile);
res = std::make_pair(edge, placement);
DBGMSG("top edge:", complex_[edge]);
}
return res;
}
/**
* @brief Constructor with default policies.
*
* @details The default cost, placement, valid and visitor policies
* are respectively : the edge length, the first point, the link condition
*/
Skeleton_blocker_contractor(GeometricSimplifiableComplex& complex)
: complex_(complex),
cost_policy_(new Edge_length_cost),
placement_policy_(new First_vertex_placement),
valid_contraction_policy_(new Link_condition_valid_contraction),
contraction_visitor_(new Contraction_visitor_()),
edge_profile_factory_(0),
initial_num_edges_heap_(0),
current_num_edges_heap_(0) {
complex_.set_visitor(this);
if (contraction_visitor_) contraction_visitor_->on_started(complex);
collect_edges();
}
/**
* @brief Constructor with customed policies.
* @remark Policies destruction is handle by the class with smart pointers.
*/
Skeleton_blocker_contractor(GeometricSimplifiableComplex& complex,
Cost_policy_ *cost_policy,
Placement_policy_ * placement_policy = new First_vertex_placement,
Valid_contraction_policy_ * valid_contraction_policy =
new Link_condition_valid_contraction,
Contraction_visitor_* contraction_visitor = new Contraction_visitor_(),
Edge_profile_factory_* edge_profile_factory = NULL) :
complex_(complex),
cost_policy_(cost_policy),
placement_policy_(placement_policy),
valid_contraction_policy_(valid_contraction_policy),
contraction_visitor_(contraction_visitor),
edge_profile_factory_(edge_profile_factory),
initial_num_edges_heap_(0),
current_num_edges_heap_(0) {
complex_.set_visitor(this);
if (contraction_visitor) contraction_visitor->on_started(complex);
collect_edges();
}
~Skeleton_blocker_contractor() {
complex_.set_visitor(0);
}
private:
void contract_edge(const Profile& profile, Placement_type placement) {
if (contraction_visitor_) contraction_visitor_->on_contracting(profile, placement);
assert(complex_.contains_vertex(profile.v0_handle()));
assert(complex_.contains_vertex(profile.v1_handle()));
assert(placement);
profile.complex().point(profile.v0_handle()) = *placement;
// remark : this is not necessary since v1 will be deactivated
// profile.complex().point(profile.v1_handle()) = *placement;
complex_.contract_edge(profile.v0_handle(), profile.v1_handle());
assert(complex_.contains_vertex(profile.v0_handle()));
assert(!complex_.contains_vertex(profile.v1_handle()));
update_changed_edges();
// the visitor could do something as complex_.remove_popable_blockers();
if (contraction_visitor_) contraction_visitor_->on_contracted(profile, placement);
}
private:
// every time the visitor's method on_changed_edge is called, it adds an
// edge to changed_edges_
std::vector< Edge_handle > changed_edges_;
/**
* @brief we update the cost and the position in the heap of an edge that has
* been changed
*/
inline void on_changed_edge(Vertex_handle a, Vertex_handle b) override {
boost::optional ab(complex_[std::make_pair(a, b)]);
assert(ab);
changed_edges_.push_back(*ab);
}
void update_changed_edges() {
// xxx do a parralel for
DBG("update edges");
// sequential loop
for (auto ab : changed_edges_) {
// 1-get the Edge_handle corresponding to ab
// 2-change the data in mEdgeArray[ab.id()]
// 3-update the heap
Edge_data& data = get_data(ab);
Profile const& profile = create_profile(ab);
data.cost() = get_cost(profile);
if (data.is_in_PQ()) {
update_in_PQ(ab, data);
} else {
insert_in_PQ(ab, data);
}
}
changed_edges_.clear();
}
private:
void on_remove_edge(Vertex_handle a, Vertex_handle b) override {
boost::optional ab((complex_[std::make_pair(a, b)]));
assert(ab);
Edge_data& lData = get_data(*ab);
if (lData.is_in_PQ()) {
remove_from_PQ(*ab, lData);
}
}
private:
/**
* @brief Called when the edge 'ax' has been added while the edge 'bx'
* is still there but will be removed on next instruction.
* We assign the index of 'bx' to the edge index of 'ax'
*/
void on_swaped_edge(Vertex_handle a, Vertex_handle b, Vertex_handle x) override {
boost::optional ax(complex_[std::make_pair(a, x)]);
boost::optional bx(complex_[std::make_pair(b, x)]);
assert(ax && bx);
complex_[*ax].index() = complex_[*bx].index();
}
private:
/**
* @brief Called when a blocker is removed.
* All the edges that passes through the blocker may be edge-contractible
* again and are thus reinserted in the heap.
*/
void on_delete_blocker(const Simplex * blocker) override {
// we go for all pairs xy that belongs to the blocker
// note that such pairs xy are necessarily edges of the complex
// by definition of a blocker
// todo uniqument utile pour la link condition
// laisser a l'utilisateur ? booleen update_heap_on_removed_blocker?
Simplex blocker_copy(*blocker);
for (auto x = blocker_copy.begin(); x != blocker_copy.end(); ++x) {
for (auto y = x; ++y != blocker_copy.end();) {
auto edge_descr(complex_[std::make_pair(*x, *y)]);
assert(edge_descr);
Edge_data& data = get_data(*edge_descr);
Profile const& profile = create_profile(*edge_descr);
data.cost() = get_cost(profile);
// If the edge is already in the heap
// its priority has not changed.
// If the edge is not present, we reinsert it
// remark : we could also reinsert the edge
// only if it is valid
if (!data.is_in_PQ()) {
insert_in_PQ(*edge_descr, data);
}
}
}
}
private:
std::shared_ptr cost_policy_;
std::shared_ptr placement_policy_;
std::shared_ptr valid_contraction_policy_;
std::shared_ptr contraction_visitor_;
// in case the user wants to do something special when the edge profile
// are created (for instance add some info)
std::shared_ptr edge_profile_factory_;
Edge_data_array edge_data_array_;
boost::scoped_ptr heap_PQ_;
int initial_num_edges_heap_;
int current_num_edges_heap_;
};
} // namespace contraction
} // namespace Gudhi
#endif // SKELETON_BLOCKER_CONTRACTOR_H_