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+/*
+ * Garland_heckbert_policies.h
+ *  Created on: Feb 10, 2015
+ * 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-Méditerranée (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 <http://www.gnu.org/licenses/>.
+ * 
+ */
+
+
+#ifndef GARLAND_HECKBERT_POLICIES_H_
+#define GARLAND_HECKBERT_POLICIES_H_
+
+#include "gudhi/Edge_contraction.h"
+#include "Error_quadric.h"
+
+template<typename EdgeProfile>
+class GH_visitor: public Gudhi::contraction::Contraction_visitor<EdgeProfile> {
+	typedef typename EdgeProfile::Complex Complex;
+	typedef typename Complex::Point Point;
+	Complex& complex_;
+public:
+	GH_visitor(Complex& complex):complex_(complex){}
+
+
+	void on_started(Complex & complex) override{
+		//Compute quadrics for every vertex v
+		//The quadric of v consists in the sum of quadric
+		//of every triangles passing through v weighted by its area
+		for(auto v : complex.vertex_range()){
+			auto & quadric_v(complex[v].quadric);
+			for(auto t : complex.triangle_range(v)){
+				auto t_it = t.begin();
+				const auto& p0(complex.point(*t_it++));
+				const auto& p1(complex.point(*t_it++));
+				const auto& p2(complex.point(*t_it++));
+				quadric_v+=Error_quadric<Point>(p0,p1,p2);
+			}
+		}
+	}
+
+	/**
+	 * @brief Called when an edge is about to be contracted and replaced by a vertex whose position is *placement.
+	 */
+	void on_contracting(EdgeProfile const &profile, boost::optional< Point > placement)
+	override{
+		profile.v0().quadric += profile.v1().quadric;
+	}
+};
+
+
+template<typename EdgeProfile>
+class GH_placement : public Gudhi::contraction::Placement_policy<EdgeProfile>{
+	typedef typename EdgeProfile::Complex Complex;
+	Complex& complex_;
+public:
+	typedef typename EdgeProfile::Point Point;
+	typedef typename Gudhi::contraction::Placement_policy<EdgeProfile>::Placement_type Placement_type;
+
+	GH_placement(Complex& complex):complex_(complex){}
+
+	Placement_type operator()(const EdgeProfile& profile) const override{
+		auto sum_quad(profile.v0().quadric);
+		sum_quad += profile.v1().quadric;
+
+		boost::optional<Point> min_quadric_pt(sum_quad.min_cost());
+		if (min_quadric_pt)
+			return Placement_type(*min_quadric_pt);
+		else
+			return profile.p0();
+	}
+};
+
+template<typename EdgeProfile>
+class GH_cost : public Gudhi::contraction::Cost_policy<EdgeProfile>{
+	typedef typename EdgeProfile::Complex Complex;
+	Complex& complex_;
+public:
+
+	typedef typename Gudhi::contraction::Cost_policy<EdgeProfile>::Cost_type Cost_type;
+	typedef typename Complex::Point Point;
+
+	GH_cost(Complex& complex):complex_(complex){}
+
+	Cost_type operator()( EdgeProfile const& profile, boost::optional<Point> const& new_point ) const override {
+		Cost_type res;
+		if (new_point){
+			auto sum_quad(profile.v0().quadric);
+			sum_quad += profile.v1().quadric;
+			res = sum_quad.cost(*new_point);
+		}
+		return res;
+	}
+};
+
+
+
+#endif /* GARLAND_HECKBERT_POLICIES_H_ */