diff --git a/vcg/complex/algorithms/local_optimization/tri_edge_collapse.h b/vcg/complex/algorithms/local_optimization/tri_edge_collapse.h
index 36364ac9..36ff5ad8 100644
--- a/vcg/complex/algorithms/local_optimization/tri_edge_collapse.h
+++ b/vcg/complex/algorithms/local_optimization/tri_edge_collapse.h
@@ -8,7 +8,7 @@
 *                                                                    \      *
 * All rights reserved.                                                      *
 *                                                                           *
-* This program is free software; you can redistribute it and/or modify      *   
+* 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 2 of the License, or         *
 * (at your option) any later version.                                       *
@@ -38,24 +38,24 @@ namespace tri{
 /// This Class is specialization of LocalModification for the edge collapse.
 /// It wraps the atomic operation EdgeCollapse to be used in a optimizatin routine.
 /// Note that it has knowledge of the heap of the class LocalOptimization because
-/// it is responsible of updating it after a collapse has been performed; 
-/// This is the base class of all the specialized collapse classes like for example Quadric Edge Collapse. 
-/// Each derived class 
+/// it is responsible of updating it after a collapse has been performed;
+/// This is the base class of all the specialized collapse classes like for example Quadric Edge Collapse.
+/// Each derived class
 
 template<class TriMeshType, class VertexPair, class MYTYPE>
 class TriEdgeCollapse: public LocalOptimization<TriMeshType>::LocModType
 {
 public:
  /// static data to gather statistical information about the reasons of collapse failures
-  class FailStat { 
+  class FailStat {
   public:
-	static int &Volume()           {static int vol=0; return vol;}
-	static int &LinkConditionFace(){static int lkf=0; return lkf;}
-	static int &LinkConditionEdge(){static int lke=0; return lke;}
-	static int &LinkConditionVert(){static int lkv=0; return lkv;}
-	static int &OutOfDate()        {static int ofd=0; return ofd;}
-	static int &Border()           {static int bor=0; return bor;}
-  static void Init() 
+  static int &Volume()           {static int vol=0; return vol;}
+  static int &LinkConditionFace(){static int lkf=0; return lkf;}
+  static int &LinkConditionEdge(){static int lke=0; return lke;}
+  static int &LinkConditionVert(){static int lkv=0; return lkv;}
+  static int &OutOfDate()        {static int ofd=0; return ofd;}
+  static int &Border()           {static int bor=0; return bor;}
+  static void Init()
   {
    Volume()           =0;
    LinkConditionFace()=0;
@@ -72,35 +72,35 @@ protected:
   typedef	typename FaceType::VertexType::CoordType CoordType;
   typedef	typename TriMeshType::VertexType::ScalarType ScalarType;
   typedef typename LocalOptimization<TriMeshType>::HeapElem HeapElem;
-	typedef typename LocalOptimization<TriMeshType>::HeapType HeapType;
+  typedef typename LocalOptimization<TriMeshType>::HeapType HeapType;
 
   TriMeshType *mt;
-	///the pair to collapse 
+  ///the pair to collapse
   VertexPair pos;
 
-	///mark for up_dating
-	static int& GlobalMark(){ static int im=0; return im;}
+  ///mark for up_dating
+  static int& GlobalMark(){ static int im=0; return im;}
 
-	///mark for up_dating
-	int localMark;
-	
-	/// priority in the heap
-	ScalarType _priority;
+  ///mark for up_dating
+  int localMark;
 
-	public:
-	/// Default Constructor
-	inline	TriEdgeCollapse()
-			{}
-	///Constructor with postype
+  /// priority in the heap
+  ScalarType _priority;
+
+  public:
+  /// Default Constructor
+  inline	TriEdgeCollapse()
+      {}
+  ///Constructor with postype
    inline TriEdgeCollapse(const VertexPair &p, int mark, BaseParameterClass *pp)
-			{    
-				localMark = mark;
-				pos=p;
+      {
+        localMark = mark;
+        pos=p;
         _priority = ComputePriority(pp);
-			}
+      }
 
-		~TriEdgeCollapse()
-			{}
+    ~TriEdgeCollapse()
+      {}
 
 private:
 
@@ -108,26 +108,26 @@ private:
 public:
 
   inline ScalarType ComputePriority(BaseParameterClass *)
-  { 
-		_priority = Distance(pos.V(0)->cP(),pos.V(1)->cP()); 
+  {
+    _priority = Distance(pos.V(0)->cP(),pos.V(1)->cP());
     return _priority;
   }
 
   virtual const char *Info(TriMeshType &m) {
-		mt = &m;
+    mt = &m;
     static char buf[60];
       sprintf(buf,"%i -> %i %g\n", int(pos.V(0)-&m.vert[0]), int(pos.V(1)-&m.vert[0]),-_priority);
    return buf;
   }
- 
+
   inline void Execute(TriMeshType &m, BaseParameterClass *)
-  {	
+  {
     CoordType MidPoint=(pos.V(0)->P()+pos.V(1)->P())/2.0;
     EdgeCollapser<TriMeshType,VertexPair>::Do(m, pos, MidPoint);
   }
-  
+
   static bool IsSymmetric(BaseParameterClass *) { return true;}
-  
+
   // This function is called after an action to re-add in the heap elements whose priority could have been changed.
   // in the plain case we just put again in the heap all the edges around the vertex resulting from the previous collapse: v[1].
   // if the collapse is not symmetric you should add also backward edges (because v0->v1 collapse could be different from v1->v0)
@@ -190,28 +190,29 @@ public:
 
   inline bool IsFeasible(BaseParameterClass *){
     return EdgeCollapser<TriMeshType,VertexPair>::LinkConditions(pos);
-	}
+  }
 
   inline bool IsUpToDate() const
   {
       VertexType *v0=pos.cV(0);
       VertexType *v1=pos.cV(1);
-			if( v0->IsD() || v1->IsD() ||
-				 localMark < v0->IMark()  ||
-		  	 localMark < v1->IMark()   )
-			{
-				++FailStat::OutOfDate();
-				return false;
+      if( v0->IsD() || v1->IsD() ||
+         localMark < v0->IMark()  ||
+         localMark < v1->IMark()   )
+      {
+        ++FailStat::OutOfDate();
+        return false;
       }
         return true;
-	}
+  }
 
-	virtual ScalarType Priority() const {
-	return _priority;
+  virtual ScalarType Priority() const {
+  return _priority;
   }
 
   static void Init(TriMeshType &m, HeapType &h_ret, BaseParameterClass *pp)
   {
+    vcg::tri::RequirePerVertexMark(m);
     vcg::tri::UpdateTopology<TriMeshType>::VertexFace(m);
     h_ret.clear();
     typename TriMeshType::FaceIterator fi;
@@ -225,7 +226,7 @@ public:
         //printf("Inserting in heap coll %3i ->%3i %f\n",p.V()-&m.vert[0],p.VFlip()-&m.vert[0],h_ret.back().locModPtr->Priority());
       }
     }
-	}
+  }
 
 };
 }//end namespace tri