Revert "refactor to remove duplicate (slower) implementation"

This reverts commit 829eaa54b6a2d9ff681bcf4982c0f5e0c5360c31.

include/igl/is_edge_manifold.cpp

@@ -34,8 +34,6 @@ IGL_INLINE bool igl::is_edge_manifold(
   // Find unique undirected edges and mapping
   VectorXF _;
   unique_simplices(allE,E,_,EMAP);
-  // could use "face_occurrences.h", but that implementation uses
-  // vector<vector>>
   std::vector<typename DerivedF::Index> count(E.rows(),0);
   for(Index e = 0;e<EMAP.rows();e++)
   {
@@ -58,16 +56,49 @@ template <typename DerivedF>
 IGL_INLINE bool igl::is_edge_manifold(
   const Eigen::MatrixBase<DerivedF>& F)
 {
-  Eigen::Array<bool,Eigen::Dynamic,Eigen::Dynamic> BF;
-  Eigen::Array<bool,Eigen::Dynamic,1> BE;
-  Eigen::MatrixXi E;
-  Eigen::VectorXi EMAP;
-  return is_edge_manifold(F,BF,E,EMAP,BE);
+  // TODO: It's bothersome that this is not calling/reusing the code from the
+  // overload above. This could result in disagreement.
+
+  // List of edges (i,j,f,c) where edge i<j is associated with corner i of face
+  // f
+  std::vector<std::vector<int> > TTT;
+  for(int f=0;f<F.rows();++f)
+    for (int i=0;i<3;++i)
+    {
+      // v1 v2 f ei
+      int v1 = F(f,i);
+      int v2 = F(f,(i+1)%3);
+      if (v1 > v2) std::swap(v1,v2);
+      std::vector<int> r(4);
+      r[0] = v1; r[1] = v2;
+      r[2] = f;  r[3] = i;
+      TTT.push_back(r);
+    }
+  // Sort lexicographically
+  std::sort(TTT.begin(),TTT.end());
+
+  for(int i=2;i<(int)TTT.size();++i)
+  {
+    // Check any edges occur 3 times
+    std::vector<int>& r1 = TTT[i-2];
+    std::vector<int>& r2 = TTT[i-1];
+    std::vector<int>& r3 = TTT[i];
+    if ( (r1[0] == r2[0] && r2[0] == r3[0])
+        &&
+        (r1[1] == r2[1] && r2[1] == r3[1]) )
+    {
+      return false;
+    }
+  }
+  return true;
 }
 
 #ifdef IGL_STATIC_LIBRARY
 // Explicit template instantiation
+// generated by autoexplicit.sh
 template bool igl::is_edge_manifold<Eigen::Matrix<unsigned int, -1, -1, 1, -1, -1> >(Eigen::MatrixBase<Eigen::Matrix<unsigned int, -1, -1, 1, -1, -1> > const&);
+// generated by autoexplicit.sh
+//template bool igl::is_edge_manifold<double>(Eigen::Matrix<double, -1, -1, 0, -1, -1> const&, Eigen::Matrix<int, -1, -1, 0, -1, -1> const&);
 template bool igl::is_edge_manifold<Eigen::Matrix<int, -1, -1, 0, -1, -1> >(Eigen::MatrixBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&);
 template bool igl::is_edge_manifold<Eigen::Matrix<int, -1, 3, 0, -1, 3> >(Eigen::MatrixBase<Eigen::Matrix<int, -1, 3, 0, -1, 3> > const&);
 #endif

include/igl/is_edge_manifold.h

@@ -13,15 +13,14 @@
 
 namespace igl 
 {
-  // check if the mesh is edge-manifold (every edge is incident one one face
-  // (boundary) or two oppositely oriented faces).
+  // check if the mesh is edge-manifold
   //
   // Inputs:
   //   F  #F by 3 list of triangle indices
-  // Outputs:
-  //   BF  #F by 3 list of flags revealing if edge opposite corresponding vertex
-  //   is non-manifold.
-  // Returns true iff all edges are manifold
+  // Returns whether mesh is edge manifold.
+  //
+  // Known Bugs:
+  //  Does not check for non-manifold vertices
   //
   // See also: is_vertex_manifold
   template <