585 lines
16 KiB
C++
585 lines
16 KiB
C++
// Copyright (c) 2004-2005 INRIA Sophia-Antipolis (France).
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// Copyright (c) 2010 GeometryFactory Sarl (France)
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// All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org).
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//
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// $URL: https://github.com/CGAL/cgal/blob/v5.1/Mesh_2/include/CGAL/Mesh_2/Clusters.h $
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// $Id: Clusters.h 8bb22d5 2020-03-26T14:23:37+01:00 Sébastien Loriot
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// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
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//
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//
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// Author(s) : Laurent Rineau
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#ifndef CGAL_MESH_2_CLUSTERS_H
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#define CGAL_MESH_2_CLUSTERS_H
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#include <CGAL/license/Mesh_2.h>
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#include <CGAL/Filter_circulator.h>
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#include <CGAL/Unique_hash_map.h>
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#include <utility>
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#include <CGAL/boost/iterator/transform_iterator.hpp>
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namespace CGAL {
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namespace Mesh_2
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{
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namespace details
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{
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template <class Tr>
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class Is_edge_constrained {
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const Tr* tr_;
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public:
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typedef Is_edge_constrained<Tr> Self;
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typedef typename Tr::Edge_circulator Edge_circulator;
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Is_edge_constrained(const Tr& tr) : tr_(&tr)
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{}
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bool operator()(const Edge_circulator& ec) const
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{
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return tr_->is_constrained(*ec);
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}
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};
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} // end namespace details
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template <class Tr>
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class Clusters
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{
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typedef typename Tr::Vertex_handle Vertex_handle;
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typedef typename Tr::Point Point;
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typedef typename Tr::Geom_traits Geom_traits;
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typedef typename Geom_traits::FT FT;
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typedef FT Squared_length; /**<This typedef is used to remind that
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the length is squared. */
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typedef typename Tr::Edge_circulator Edge_circulator;
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/**
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* Special type: filtered circulator that returns only constrained
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* edges.
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*/
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typedef Filter_circulator<Edge_circulator,
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details::Is_edge_constrained<Tr> >
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Constrained_edge_circulator;
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public:
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/** \name Clusters public types */
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/**
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* \c Cluster register several informations about clusters.
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* A cluster is a set of vertices v_i incident to one vertice
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* v_0, so that angles between segments [v_0, v_i] is less than 60
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* degres.
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*/
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struct Cluster {
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bool reduced ; /**< Is the cluster reduced? */
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/**
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* Smallest_angle gives the two vertices defining the
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* smallest angle in the cluster.
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*/
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std::pair<Vertex_handle, Vertex_handle> smallest_angle;
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FT rmin; // @fixme: rmin has no meaning if reduced=false!!!
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Squared_length minimum_squared_length;
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/**
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* The following map tells what vertices are in the cluster and if
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* the corresponding segment has been split once.
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*/
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typedef std::map<Vertex_handle, bool> Vertices_map;
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Vertices_map vertices;
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bool is_reduced() const {
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return reduced;
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}
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bool is_reduced(const Vertex_handle v) {
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return vertices[v];
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}
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};
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private:
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/** \name Clusters associated types */
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typedef std::multimap<Vertex_handle, Cluster> Cluster_map;
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typedef typename Cluster_map::value_type Cluster_map_value_type;
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template <class Pair>
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struct Pair_get_first
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: public CGAL::cpp98::unary_function<Pair, typename Pair::first_type>
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{
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typedef typename Pair::first_type result;
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const result& operator()(const Pair& p) const
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{
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return p.first;
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}
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};
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typedef typename Cluster::Vertices_map Cluster_vertices_map;
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private:
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/* --- protected datas --- */
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Tr& tr; /**< The triangulation itself. */
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/**
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* Multimap \c Vertex_handle -> \c Cluster
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* Each vertex can have several clusters.
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*/
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Cluster_map cluster_map;
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public:
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typedef typename Cluster_map::const_iterator const_iterator;
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typedef typename Cluster_map::iterator iterator;
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Clusters(Tr& tr_) : tr(tr_)
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{
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}
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/** For all vertices, calls create_clusters_of_vertex(). */
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void create_clusters() {
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create_clusters(typename Tr::Constraint_hierarchy_tag());
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}
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// function that depends of Tr::Constraint_hierarchy_tag
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template <typename Constraint_hierarchy_tag>
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void create_clusters(Constraint_hierarchy_tag) {
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cluster_map.clear();
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for(typename Tr::Finite_vertices_iterator vit = tr.finite_vertices_begin();
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vit != tr.finite_vertices_end();
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vit++)
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{
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create_clusters_of_vertex(vit);
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}
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}
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void create_clusters(Tag_true) {
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cluster_map.clear();
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Unique_hash_map<Vertex_handle,bool> created(false);
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for(typename Tr::Subconstraint_iterator it = tr.subconstraints_begin();
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it != tr.subconstraints_end(); ++it) {
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Vertex_handle vh = it->first.first;
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if(!created[vh]){
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created[vh] = true;
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create_clusters_of_vertex(vh);
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}
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vh = it->first.second;
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if(!created[vh]){
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created[vh] = true;
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create_clusters_of_vertex(vh);
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}
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}
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}
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private:
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/**
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* Computes clusters of the vertex \c v, using the auxiliary function
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* construct_cluster().
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*/
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void create_clusters_of_vertex(const Vertex_handle v);
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/**
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* Adds the sequence [\c begin, \c end] to the cluster \c c and adds it
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* to the clusters of the vertex \c v.
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*/
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void construct_cluster(const Vertex_handle v,
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const Constrained_edge_circulator& begin,
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const Constrained_edge_circulator& end,
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Cluster c = Cluster());
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public:
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/** \name Functions to manage clusters during the refinement process. */
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/**
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* Update the cluster of [\c va,\c vb], putting \c vm instead of \c vb.
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* If reduction=false, the edge [va,vm] is not set reduced.
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*/
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void update_cluster(Cluster& c, iterator it,
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const Vertex_handle va, const Vertex_handle vb,
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const Vertex_handle vm,
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bool reduction = true);
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/**
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* Returns the cluster of [\c va,\c vb] in \c c and return true
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* if it is in a cluster. Returns also a const_iterator in \c it.
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*/
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bool get_cluster(const Vertex_handle va, const Vertex_handle vb,
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Cluster& c, iterator& it);
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/** Const version of get_cluster(). */
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bool get_cluster(const Vertex_handle va, const Vertex_handle vb,
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Cluster& c, const_iterator& it) const;
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/** \name Auxiliary functions that return a boolean. */
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/**
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* Tells if the angle <pleft, pmiddle, pright> is less than 60 degres.
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* Uses squared_cosine_of_angle_times_4() and used by
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* create_clusters_of_vertex().
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*/
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bool is_small_angle(const Point& pleft,
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const Point& pmiddle,
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const Point& pright) const;
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private:
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/** \name Helping computing functions */
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/** Returns the squared cosine of the angle <pleft, pmiddle, pright>
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times 4. */
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FT squared_cosine_of_angle_times_4(const Point& pleft,
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const Point& pmiddle,
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const Point& pright) const;
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/** Helper functions to access the two vertices of an Edge
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source is the vertex around which the circulator turns. */
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//@{
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Vertex_handle source(const Edge_circulator& ec) const
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{
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return ec->first->vertex(tr.cw(ec->second));
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}
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Vertex_handle target(const Edge_circulator& ec) const
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{
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return ec->first->vertex(tr.ccw(ec->second));
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}
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//@}
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public:
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/** \name CONST ACCESS FUNCTIONS */
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typedef typename boost::transform_iterator<
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Pair_get_first<typename Cluster_map::value_type>,
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typename Cluster_map::const_iterator>
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Cluster_vertices_iterator;
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typedef typename boost::transform_iterator<
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Pair_get_first<typename Cluster_vertices_map::value_type>,
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typename Cluster_vertices_map::const_iterator>
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Vertices_in_cluster_iterator;
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int size() const
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{
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return cluster_map.size();
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}
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Cluster_vertices_iterator clusters_vertices_begin() const
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{
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return Cluster_vertices_iterator(cluster_map.begin());
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}
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Cluster_vertices_iterator clusters_vertices_end() const
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{
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return Cluster_vertices_iterator(cluster_map.end());
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}
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unsigned int number_of_clusters_at_vertex(const Vertex_handle& vh) const
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{
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typedef typename Cluster_map::const_iterator Iterator;
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typedef std::pair<Iterator, Iterator> Range;
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Range range = cluster_map.equal_range(vh);
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return std::distance(range.first, range.second);
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}
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// returns the sequence of vertices bellonging to the n-th cluster of vh
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std::pair<Vertices_in_cluster_iterator, Vertices_in_cluster_iterator>
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vertices_in_cluster_sequence(const Vertex_handle& vh,
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const unsigned int n) const
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{
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typedef typename Cluster_map::const_iterator Iterator;
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typedef std::pair<Iterator, Iterator> Range;
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Range range = cluster_map.equal_range(vh);
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Iterator first = range.first;
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std::advance(first, n);
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const Cluster& c = first->second;
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return
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std::make_pair(Vertices_in_cluster_iterator(c.vertices.begin()),
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Vertices_in_cluster_iterator(c.vertices.end()));
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}
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}; // end class Clusters
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template <typename Tr>
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void Clusters<Tr>::
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update_cluster(Cluster& c, iterator it, Vertex_handle va,
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Vertex_handle vb, Vertex_handle vm, bool reduction)
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{
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typename Geom_traits::Compute_squared_distance_2 squared_distance =
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tr.geom_traits().compute_squared_distance_2_object();
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cluster_map.erase(it);
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c.vertices.erase(vb);
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c.vertices[vm] = reduction;
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if(false == reduction) {
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for(typename Cluster::Vertices_map::iterator
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it = c.vertices.begin(),
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end = c.vertices.end();
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it != end; ++it)
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{
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it->second = false;
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}
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}
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if(vb==c.smallest_angle.first)
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c.smallest_angle.first = vm;
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if(vb==c.smallest_angle.second)
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c.smallest_angle.second = vm;
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FT l = squared_distance(va->point(),vm->point());
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if(l<c.minimum_squared_length)
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c.minimum_squared_length = l;
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if(!c.is_reduced())
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{
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typename Cluster::Vertices_map::iterator it = c.vertices.begin();
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while(it!=c.vertices.end() && c.is_reduced(it->first))
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++it; // @todo: use std::find and an object class
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if(it==c.vertices.end())
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c.reduced = true;
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}
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if(c.is_reduced())
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c.rmin = squared_distance(c.smallest_angle.first->point(),
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c.smallest_angle.second->point())/FT(4);
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cluster_map.insert(Cluster_map_value_type(va,c));
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#ifdef CGAL_MESH_2_DEBUG_CLUSTERS
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std::cerr << "Cluster at " << va->point() << " is updated. "
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<< "\n vm: " << vm->point()
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<< "\n reduction: " << reduction
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<< "\n min_sq_len: " << c.minimum_squared_length
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<< "\n";
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#endif // CGAL_MESH_2_DEBUG_CLUSTERS
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}
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template <typename Tr>
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bool Clusters<Tr>::
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get_cluster(Vertex_handle va, Vertex_handle vb, Cluster& c,
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const_iterator& it) const
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{
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typedef std::pair<const_iterator, const_iterator> Range;
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Range range = cluster_map.equal_range(va);
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for(it = range.first; it != range.second; it++)
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{
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const Cluster &cl = it->second;
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if(cl.vertices.find(vb)!=cl.vertices.end()) {
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c = it->second;
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return true;
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}
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}
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return false;
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}
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template <typename Tr>
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bool Clusters<Tr>::
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get_cluster(Vertex_handle va, Vertex_handle vb, Cluster& c,
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iterator& it)
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{
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typedef std::pair<iterator, iterator> Range;
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Range range = cluster_map.equal_range(va);
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for(it = range.first; it != range.second; it++)
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{
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const Cluster &cl = it->second;
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if(cl.vertices.find(vb)!=cl.vertices.end()) {
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c = it->second;
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return true;
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}
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}
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return false;
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}
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template <typename Tr>
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void Clusters<Tr>::
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create_clusters_of_vertex(const Vertex_handle v)
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{
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details::Is_edge_constrained<Tr> test(tr);
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Constrained_edge_circulator begin(tr.incident_edges(v),test);
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// This circulator represents all constrained edges around the
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// vertex v. An edge [v,v'] is represented by the vertex v'.
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if(begin == 0) return; // if there is only one vertex
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Constrained_edge_circulator
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current(begin), next(begin), cluster_begin(begin);
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++next; // next is always just after current.
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if(current == next) return;
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bool in_a_cluster = false;
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do
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{
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if(is_small_angle(target(current)->point(), v->point(),
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target(next)->point()))
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{
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if(!in_a_cluster)
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{
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// at this point, current is the beginning of a cluster
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in_a_cluster = true;
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cluster_begin = current;
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}
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}
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else {
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if(in_a_cluster)
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{
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// at this point, current is the end of a cluster and
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// cluster_begin is its beginning
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construct_cluster(v, cluster_begin, current);
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in_a_cluster = false;
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}
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}
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current = next;
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++next;
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} while( current!=begin );
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if(in_a_cluster)
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{
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Cluster c;
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iterator it;
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if(get_cluster(v, target(begin), c, it))
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{
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// get the cluster and erase it from the clusters map
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cluster_map.erase(it);
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construct_cluster(v, cluster_begin, begin, c);
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}
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else
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construct_cluster(v, cluster_begin, current);
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}
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}
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template <typename Tr>
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void Clusters<Tr>::
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construct_cluster(Vertex_handle v,
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const Constrained_edge_circulator& begin,
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const Constrained_edge_circulator& end,
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Cluster c)
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{
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typename Geom_traits::Compute_squared_distance_2 squared_distance =
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tr.geom_traits().compute_squared_distance_2_object();
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if(c.vertices.empty())
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{
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c.reduced = false;
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// c.rmin is not initialized because
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// reduced=false!
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c.minimum_squared_length =
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squared_distance(v->point(), target(begin)->point());
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Constrained_edge_circulator second(begin);
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++second;
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c.smallest_angle.first = target(begin);
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c.smallest_angle.second = target(second);
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}
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const bool all_edges_in_cluster = (begin == end); // tell if all incident edges
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// are in the cluster
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const Point& vp = v->point();
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FT greatest_cosine =
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squared_cosine_of_angle_times_4(c.smallest_angle.first->point(),
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v->point(),
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c.smallest_angle.second->point());
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bool one_full_loop_is_needed = all_edges_in_cluster;
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bool stop = false;
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Constrained_edge_circulator circ(begin);
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Constrained_edge_circulator next(begin);
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while(!stop)
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{
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c.vertices[target(circ)] = false;
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Squared_length l = squared_distance(vp,
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target(circ)->point());
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c.minimum_squared_length =
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(std::min)(l,c.minimum_squared_length);
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if(circ!=end || one_full_loop_is_needed)
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{
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FT cosine =
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squared_cosine_of_angle_times_4(target(circ)->point(),
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v->point(),
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target(next)->point());
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if(cosine>greatest_cosine)
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{
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greatest_cosine = cosine;
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c.smallest_angle.first = target(circ);
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c.smallest_angle.second = target(next);
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}
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}
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if(one_full_loop_is_needed) {
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one_full_loop_is_needed = false;
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} else {
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stop = (circ == end);
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}
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++circ;
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++next;
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}
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typedef typename Cluster_map::value_type Value_key_pair;
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cluster_map.insert(Value_key_pair(v,c));
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}
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template <typename Tr>
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bool Clusters<Tr>::
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is_small_angle(const Point& pleft,
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const Point& pmiddle,
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const Point& pright) const
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{
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typename Geom_traits::Angle_2 angle =
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tr.geom_traits().angle_2_object();
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typename Geom_traits::Orientation_2 orient =
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tr.geom_traits().orientation_2_object();
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if( angle(pleft, pmiddle, pright)==OBTUSE )
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return false;
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if( orient(pmiddle,pleft,pright)==RIGHT_TURN)
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return false;
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|
|
|
FT cos_alpha = squared_cosine_of_angle_times_4(pleft, pmiddle,
|
|
pright);
|
|
|
|
if(cos_alpha > 1)
|
|
{
|
|
return true; //the same cluster
|
|
}
|
|
else
|
|
{
|
|
return false; //another cluster
|
|
}
|
|
}
|
|
|
|
template <typename Tr>
|
|
typename Clusters<Tr>::FT
|
|
Clusters<Tr>::
|
|
squared_cosine_of_angle_times_4(const Point& pb, const Point& pa,
|
|
const Point& pc) const
|
|
{
|
|
typename Geom_traits::Compute_squared_distance_2 squared_distance =
|
|
tr.geom_traits().compute_squared_distance_2_object();
|
|
|
|
const FT
|
|
a = squared_distance(pb, pc),
|
|
b = squared_distance(pa, pb),
|
|
c = squared_distance(pa, pc);
|
|
|
|
const FT num = a-(b+c);
|
|
|
|
return (num*num)/(b*c);
|
|
}
|
|
|
|
} // end namespace Mesh_2
|
|
|
|
} // end namespace CGAL
|
|
|
|
#endif // CGAL_MESH_2_CLUSTERS_H
|