diff --git a/apps/nexus/nexus.cpp b/apps/nexus/nexus.cpp
index a13364b5..000c16ec 100644
--- a/apps/nexus/nexus.cpp
+++ b/apps/nexus/nexus.cpp
@@ -28,8 +28,8 @@ bool Nexus::Create(const string &file) {
     cerr << "Could not create file: " << file << ".nxp" << endl;
     return false;
   }
-  if(!borders.Create(file + ".nxb")) {
-    cerr << "Could not create file: " << file << ".nxp" << endl;
+  if(!borders.Create(file + ".nxb", 1)) {
+    cerr << "Could not create file: " << file << ".nxb" << endl;
     return false;
   }
   return true;
@@ -59,8 +59,8 @@ bool Nexus::Load(const string &file) {
   readed = fread(&index[0], sizeof(Entry), size, index_file);
   if(readed != size) return false;
 
-  if(!patches.Load(file + ".nxp")) return false;
-  if(!borders.Load(file + ".nxb")) return false;
+  if(!patches.Load(file + ".nxp", 1)) return false;
+  if(!borders.Load(file + ".nxb", 1)) return false;
   return true;
 }
 
@@ -84,6 +84,114 @@ void Nexus::Close() {
 
 Patch Nexus::GetPatch(unsigned int patch) {
   Entry &entry = index[patch];
-  Chunk *start = patches.GetRegion(entry.patch_offset, entry.patch_size);
-  return Patch(start);
+  Chunk *start = patches.GetRegion(entry.patch_start, entry.patch_size);
+  return Patch(start, entry.nvert, entry.nface);
+}
+
+Border Nexus::GetBorder(unsigned int patch) {
+  Entry &entry = index[patch];
+  Link *start = borders.GetRegion(entry.border_start, entry.border_size);
+  return Border(start, entry.border_size);
+}
+
+
+unsigned int Nexus::AddPatch(unsigned int nvert, unsigned int nface,
+			     unsigned int nbord) {
+  Entry entry;
+  entry.patch_start = patches.Size();
+  entry.patch_size = Patch::ChunkSize(nvert, nface);
+  entry.border_start = borders.Size();
+  entry.border_size = nbord;
+  entry.nvert = nvert;
+  entry.nface = nface;
+  
+  patches.Resize(patches.Size() + entry.patch_size);
+  borders.Resize(borders.Size() + nbord);
+  index.push_back(entry);
+  return index.size() -1;
+}
+
+void Nexus::Join(std::vector<unsigned int> &patches,
+		 std::vector<Point3f &newvert,
+		 std::vector<unsigned int> &newface,
+		 std::vector<Link> &newlinks) {
+
+  map<unsigned int, vector<unsigned int> > remap;
+
+  vector<unsigned int>::iterator i;
+  for(i = patches.begin(); i != patches.end(); i++) {
+    unsigned int patch = *i;
+    Nexus::Entry &entry = index[patch];
+    remap[*i].resize(entry.nvert, 0xffffffff);
+  }
+  unsigned int vcount = 0;
+  unsigned int fcount = 0;
+  unsigned int bcount = 0;
+  for(i = patches.begin(); i != patches.end(); i++) {
+    unsigned int patch = *i;
+    Nexus::Entry &entry = index[patch];
+    fcount += entry.nface;
+    assert(fcount < 0xffff);
+    for(unsigned int k = 0; k < entry.nvert; k++) {
+      if(remap[patch][k] == 0xffffffff) { //first time
+	remap[patch][k] = vcount++;
+      }
+    }
+
+    Border border = GetBorder(patch);
+    for(unsigned int k = 0; k < border.Size(); k++) {
+      Link &link = border[k];
+      if(!remap.count(link.end_patch)) {
+	bcount++;
+	continue;
+      }
+      if(remap[link.end_patch][link.end_vert] == 0xffffffff) { //first time
+	remap[link.end_patch][link.end_vert] = remap[patch][link.start_vert];
+      }
+    }
+  }
+
+
+
+  newvert.resize(vcount);
+  newface.resize(fcount*3);
+  newbord.resize(bcount);
+
+  fcount = 0;
+  bcount = 0;
+  for(i = patches.begin(); i != patches.end(); i++) {
+    Patch patch = GetPatch(*i);
+    Border border = GetBorder(*i);
+    vector<unsigned int> &vmap = remap[*i];
+
+    for(unsigned int i = 0; i < patch.VertSize(); i++)
+      newvert[vmap[i]] = patch.Vert(i);
+
+    for(unsigned int i = 0; i < patch.FaceSize(); i++) {
+      for(int k = 0; k < 3; k++) {
+	newface[3*fcount + k] = vmap[patch.Face(i)[k]];
+      }
+      fcount++;
+    }
+    for(unsigned int i = 0; i < border.Size(); i++) {
+      Link &link = border[i];
+      if(remap.count(link.end_patch)) continue;
+      Link newlink = link;
+      newlink.start_vert = vmap[link.start_vert];
+      newbord[bcount++] = newlink;
+    }
+  }  
+  unsigned int newentry = AddPatch(vcount, fcount, bcount);
+  Patch newpatch = GetPatch(newentry);
+  Border newborder = GetBorder(newentry);
+
+  memcpy(newpatch.VertBegin(), &(newvert)[0],
+	 newvert.size() * sizeof(Point3f));
+
+  memcpy(newpatch.FaceBegin(), &(newface)[0],
+	 newface.size() * sizeof(unsigned short));
+
+  memcpy(&(newborder[0]), &(newbord[0]),
+	 newbord.size() * sizeof(Link));
+  return newentry;
 }
diff --git a/apps/nexus/nexus.h b/apps/nexus/nexus.h
index 16ea789d..495d81c9 100644
--- a/apps/nexus/nexus.h
+++ b/apps/nexus/nexus.h
@@ -17,12 +17,16 @@ class Nexus {
 
   class Entry {
   public:
-    Entry(): patch_offset(0xffffffff), border_offset(0xffffffff),
-      patch_size(0), border_size(0), sphere(vcg::Sphere3f()) {}
-    unsigned int patch_offset;  //granularita' Chunk
-    unsigned int border_offset; //granuralita' Link
+    Entry(): patch_start(0xffffffff), border_start(0xffffffff),
+      patch_size(0), border_size(0), 
+      nvert(0), nface(0), sphere(vcg::Sphere3f()) {}
+    unsigned int patch_start;  //granularita' Chunk
+    unsigned int border_start; //granuralita' Link
     unsigned short patch_size;  //in cuhnks
     unsigned short border_size; //in Links
+
+    unsigned short nvert;
+    unsigned short nface;
     vcg::Sphere3f sphere;
   };
 
@@ -33,10 +37,21 @@ class Nexus {
   void Close();
 
   Patch GetPatch(unsigned int patch);
-  void GetBorder(unsigned int border, Border &border);
+  Border GetBorder(unsigned int patch);
 
-  //  unsigned int addPatch(Patch *builder);
-  void AddBorder(unsigned int patch, std::vector<Link> &links);
+  unsigned int AddPatch(unsigned int nvert, unsigned int nface, 
+			unsigned int nbord);
+
+  //  unsigned int Join(std::vector<unsigned int> &patches);
+  void Join(std::vector<unsigned int> &patches,
+	    std::vector<Point3f &vert,
+	    std::vector<unsigned int> &faces,
+	    std::vector<Link> &links);
+
+  //TODO implement theese
+  void CompactBorder(unsigned int patch);
+  void CompactBorders();
+  void CompactPatches();
   
   unsigned int totvert;
   unsigned int totface;
@@ -46,9 +61,10 @@ class Nexus {
     
   std::vector<Entry> index;
 
-  FILE *index_file;
   VFile<Chunk> patches;
   VFile<Link> borders; 
+ private:
+  FILE *index_file;
 };
 
 }