test is manifold

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/gudhi/trunk@437 636b058d-ea47-450e-bf9e-a15bfbe3eedb

Former-commit-id: a515b3216d21c8a5736744842fdcf09644f5c7b1

1 files changed, 104 insertions, 0 deletions

diff --git a/src/GudhUI/utils/Is_manifold.h b/src/GudhUI/utils/Is_manifold.h
new file mode 100644
index 00000000..e708a6a4
--- /dev/null
+++ b/src/GudhUI/utils/Is_manifold.h
@@ -0,0 +1,104 @@
+/*
+ * Is_manifold.h
+ *  Created on: Jan 28, 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 IS_MANIFOLD_H_
+#define IS_MANIFOLD_H_
+
+#include "utils/UI_utils.h"
+
+#include "utils/Edge_contractor.h"
+
+/**
+ * Iteratively tries to anticollapse smallest edge non added so far.
+ * If its link is contractible then no topological change and else possible topological change.
+ *
+ * todo do a sparsification with some parameter eps while growing
+ */
+template<typename SkBlComplex> class Is_manifold{
+private:
+	const SkBlComplex& input_complex_;
+	typedef typename SkBlComplex::Vertex_handle Vertex_handle;
+
+
+public:
+	/*
+	 * return dim the maximum dimension around one simplex and res which is true if the complex is a manifold.
+	 * If the complex has dimension <= 3 then if res is false, the complex is not a manifold.
+	 * For d-manifold with d>=4, res may be false while the complex is a manifold.
+	 */
+	Is_manifold(const SkBlComplex& input_complex,unsigned& dim,bool & res):input_complex_(input_complex){
+		res = true;
+		dim = -1;
+		if(!input_complex_.empty()){
+			for(auto v : input_complex_.vertex_range()){
+				dim = local_dimension(v);
+				break;
+			}
+			//check that the link of every vertex is a dim-1 sphere
+			for(auto v : input_complex_.vertex_range()){
+				if(!is_k_sphere(v,dim-1)) {
+					res = false;
+					break;
+				}
+			}
+		}
+	}
+
+private:
+	unsigned local_dimension(Vertex_handle v){
+		unsigned dim = 0;
+		for(const auto& s: input_complex_.simplex_range(v))
+			dim = (std::max)(dim,(unsigned)s.dimension());
+		return dim;
+	}
+
+	bool is_k_sphere(Vertex_handle v,int k){
+		auto link = input_complex_.link(v);
+		Edge_contractor<Complex> contractor(link,link.num_vertices()-1);
+		return (is_sphere_simplex(link)==k);
+	}
+
+	// A minimal sphere is a complex that contains vertices v1...vn and all faces
+	// made upon this set except the face {v1,...,vn}
+	// return -2 if not a minimal sphere
+	// and d otherwise if complex is a d minimal sphere
+	template<typename SubComplex>
+	int is_sphere_simplex(const SubComplex& complex){
+		if(complex.empty()) return -1;
+		if(complex.num_blockers()!=1) return -2;
+
+		//necessary and sufficient condition : there exists a unique blocker that passes through all vertices
+		auto first_blocker = *(complex.const_blocker_range().begin());
+
+		if (first_blocker->dimension()+1 != complex.num_vertices())
+			return -2;
+		else
+			return (first_blocker->dimension()-1);
+	}
+};
+
+#endif /* IS_MANIFOLD_H_ */