diff --git a/EgtGraphics.rc b/EgtGraphics.rc
index 31abc0b..6a8e012 100644
Binary files a/EgtGraphics.rc and b/EgtGraphics.rc differ
diff --git a/ObjEGrGraphics.h b/ObjEGrGraphics.h
index d3b555d..4428c0c 100644
--- a/ObjEGrGraphics.h
+++ b/ObjEGrGraphics.h
@@ -31,7 +31,7 @@ class ObjEGrGraphics : public IObjGraphics
       virtual bool IsValid( void) = 0 ;
       virtual void SetScene( Scene* pScene) = 0 ;
       virtual Scene* GetScene( void) = 0 ;
-      virtual bool SetCurrent( int nCurr) { return false ; }
+      virtual bool SetCurrent( int nCurr) = 0 ;
       virtual void Clear( void) = 0 ;
       virtual bool Validate( void) = 0 ;
       virtual bool AddColor( const Color& colC) = 0 ;
diff --git a/ObjNewGraphics.h b/ObjNewGraphics.h
index e3e6221..9fd5e50 100644
--- a/ObjNewGraphics.h
+++ b/ObjNewGraphics.h
@@ -69,6 +69,8 @@ class ObjNewGraphics : public ObjEGrGraphics
               { m_pScene = pScene ; }
       Scene* GetScene( void) override
               { return m_pScene ; }
+      bool SetCurrent( int nCurr) override
+              { return ( nCurr == 0) ; }
       void Clear( void) override ;
       bool Validate( void) override ;
       bool AddColor( const Color& colC) override ;
diff --git a/ObjOldGraphics.h b/ObjOldGraphics.h
index aa05447..9964089 100644
--- a/ObjOldGraphics.h
+++ b/ObjOldGraphics.h
@@ -74,6 +74,8 @@ class ObjOldGraphics : public ObjEGrGraphics
               { m_pScene = pScene ; }
       Scene* GetScene( void) override
               { return m_pScene ; }
+      bool SetCurrent( int nCurr) override
+              { return ( nCurr == 0) ; }
       void Clear( void) override ;
       bool Validate( void) override ;
       bool AddColor( const Color& colC) override ;
diff --git a/SceneGeom.cpp b/SceneGeom.cpp
index 44d3707..a7cd8a4 100644
--- a/SceneGeom.cpp
+++ b/SceneGeom.cpp
@@ -228,6 +228,10 @@ Scene::DrawGeoObj( const IGdbIterator& iIter, int nPass, const MdStMkCol& siObj)
   // recupero eventuale parte custom
    const IUserObj* pUserObj = iIter.GetUserObj() ;
 
+  // numero di colori per TriMesh e Zmap
+   const int STM_COL = 2 ;
+   const int ZMAP_COL = 2 ;
+
   // se non esiste grafica associata, la creo
    if ( pGeoObj->GetObjGraphics() == nullptr) {
      // oggetto grafico molteplice solo per Zmap o superfici che lo richiedono
@@ -236,7 +240,7 @@ Scene::DrawGeoObj( const IGdbIterator& iIter, int nPass, const MdStMkCol& siObj)
          const IVolZmap* pZmap = GetVolZmap( pGeoObj) ;
          if ( pZmap != nullptr) {
             if ( ( m_nShowZmap & ZSM_SURF) != 0)
-               nCount += 2 * pZmap->GetBlockCount() ;
+               nCount += ZMAP_COL * pZmap->GetBlockCount() ;
             if ( ( m_nShowZmap & ZSM_LINES) != 0  ||  ( m_nShowZmap & ZSM_NORMALS) != 0)
                nCount += 1 ;
             if ( pZmap->GetShowEdges())
@@ -247,7 +251,7 @@ Scene::DrawGeoObj( const IGdbIterator& iIter, int nPass, const MdStMkCol& siObj)
          const ISurfTriMesh* pSTM = GetSurfTriMeshAux( pGeoObj) ;
          if ( pSTM != nullptr) {
             if ( pSTM->GetMaxTFlag() > 0)
-               nCount = 2 ;
+               nCount = STM_COL ;
             else
                nCount = 1 ;
             if ( pSTM->GetShowEdges())
@@ -420,8 +424,6 @@ Scene::DrawGeoObj( const IGdbIterator& iIter, int nPass, const MdStMkCol& siObj)
          }
         // altrimenti superficie con due colori
          else {
-           // numero di colori
-            const int STM_COL = 2 ;
            // definizione materiali
             Material mMat[STM_COL] ;
             Color cCol[STM_COL] ;
@@ -507,8 +509,6 @@ Scene::DrawGeoObj( const IGdbIterator& iIter, int nPass, const MdStMkCol& siObj)
             return false ;
         // numero di blocchi
          int nCount = 0 ;
-        // numero di colori
-         const int ZMAP_COL = 2 ;
         // indicazione se tridexel
          bool bIsTriDexel = pZmap->IsTriDexel() ;
         // se triangoli da disegnare
@@ -536,9 +536,9 @@ Scene::DrawGeoObj( const IGdbIterator& iIter, int nPass, const MdStMkCol& siObj)
            // Ciclo sui blocchi
             nCount = pZmap->GetBlockCount() ;
             for ( int i = 0 ; i < nCount ; ++ i) {
-              // Se blocco già aggiornato, vado oltre
-               pGraphics->SetCurrent( ZMAP_COL * i) ;
-               if ( pZmap->GetBlockUpdatingCounter( i) <= pGraphics->GetCounter())
+              // Se blocco non esistente o già aggiornato, vado oltre
+               if ( ! pGraphics->SetCurrent( ZMAP_COL * i)  ||
+                    pZmap->GetBlockUpdatingCounter( i) <= pGraphics->GetCounter())
                   continue ;
               // Recupero i triangoli del blocco
                TRIA3DEXVECTOR vTria ;
@@ -553,9 +553,11 @@ Scene::DrawGeoObj( const IGdbIterator& iIter, int nPass, const MdStMkCol& siObj)
                }
               // Ciclo sui colori
                for ( int j = 0 ; j < ZMAP_COL ; ++ j) {
-                 // Imposto indice blocco corrente e lo pulisco
-                  if ( pGraphics->SetCurrent( ZMAP_COL * i + j))
-                     pGraphics->Clear() ;
+                 // Imposto indice blocco corrente, se non esiste passo oltre
+                  if ( ! pGraphics->SetCurrent( ZMAP_COL * i + j))
+                     continue ;
+                 // lo pulisco
+                  pGraphics->Clear() ;
                  // se non ci sono triangoli, passo oltre
                   if ( nTri[j] == 0)
                      continue ;
@@ -583,59 +585,65 @@ Scene::DrawGeoObj( const IGdbIterator& iIter, int nPass, const MdStMkCol& siObj)
         // visualizzazione spilloni e normali (sempre nell'ultimo blocco)
          bool bLinNrmShow = ( ( m_nShowZmap & ZSM_LINES) != 0  ||  ( m_nShowZmap & ZSM_NORMALS) != 0) ;
          if ( bLinNrmShow) {
-           // imposto indice blocco corrente e lo pulisco
-            if ( pGraphics->SetCurrent( ZMAP_COL * nCount))
+           // imposto indice blocco corrente
+            if ( pGraphics->SetCurrent( ZMAP_COL * nCount)) {
+              // lo pulisco
                pGraphics->Clear() ;
-           // ciclo sui tre gruppi di spilloni
-            int nKmin = ( m_nShowZmap & ZSM_LINES) != 0 ? 0 : 3 ;
-            int nKmax = ( m_nShowZmap & ZSM_NORMALS) != 0 ? 6 : 3 ;
-            Color vCol[6] = {BLUE, RED, GREEN, BLUE, RED, GREEN} ;
-            for ( int k = nKmin ; k < nKmax ; ++ k) {
-               pGraphics->AddColor( vCol[k]) ;
-               pGraphics->AddMaterial( vCol[k], vCol[k], vCol[k], 10) ;
-               pGraphics->AddBackMaterial( vCol[k]) ;
-               PNTVECTOR vPnt ;
-               for ( int i = 0 ; ; ++ i) {
-                  bool bOutBreak = false ;
-                  for ( int j = 0 ; ; ++ j) {
-                     POLYLINELIST lstPL ;
-                     if ( pZmap->GetDexelLines( k, j, i, lstPL)) {
-                        for ( const auto& PL : lstPL) {
-                           Point3d ptS, ptE ;
-                           bool Found = PL.GetFirstLine( ptS, ptE) ;
-                           while ( Found) {
-                              vPnt.emplace_back( ptS) ;
-                              vPnt.emplace_back( ptE) ;
-                              Found = PL.GetNextLine( ptS, ptE) ;
+              // ciclo sui tre gruppi di spilloni
+               int nKmin = ( m_nShowZmap & ZSM_LINES) != 0 ? 0 : 3 ;
+               int nKmax = ( m_nShowZmap & ZSM_NORMALS) != 0 ? 6 : 3 ;
+               Color vCol[6] = {BLUE, RED, GREEN, BLUE, RED, GREEN} ;
+               for ( int k = nKmin ; k < nKmax ; ++ k) {
+                  pGraphics->AddColor( vCol[k]) ;
+                  pGraphics->AddMaterial( vCol[k], vCol[k], vCol[k], 10) ;
+                  pGraphics->AddBackMaterial( vCol[k]) ;
+                  PNTVECTOR vPnt ;
+                  for ( int i = 0 ; ; ++ i) {
+                     bool bOutBreak = false ;
+                     for ( int j = 0 ; ; ++ j) {
+                        POLYLINELIST lstPL ;
+                        if ( pZmap->GetDexelLines( k, j, i, lstPL)) {
+                           for ( const auto& PL : lstPL) {
+                              Point3d ptS, ptE ;
+                              bool Found = PL.GetFirstLine( ptS, ptE) ;
+                              while ( Found) {
+                                 vPnt.emplace_back( ptS) ;
+                                 vPnt.emplace_back( ptE) ;
+                                 Found = PL.GetNextLine( ptS, ptE) ;
+                              }
                            }
                         }
-                     }
-                     else {
-                        if ( j == 0)
-                           bOutBreak = true ;
-                        break ;
-                     }
-                  } 
-                  if ( bOutBreak)
-                     break ;    
+                        else {
+                           if ( j == 0)
+                              bOutBreak = true ;
+                           break ;
+                        }
+                     } 
+                     if ( bOutBreak)
+                        break ;    
+                  }
+                  if ( vPnt.size() > 0)
+                     pGraphics->AddLines( vPnt) ;
                }
-               if ( vPnt.size() > 0)
-                  pGraphics->AddLines( vPnt) ;
             }
          }
         // eventuali spigoli vivi
          if ( pZmap->GetShowEdges()) {
-            if ( pGraphics->SetCurrent( ZMAP_COL * nCount + ( bLinNrmShow ? 1 : 0)))
+           // imposto indice blocco corrente
+            if ( pGraphics->SetCurrent( ZMAP_COL * nCount + ( bLinNrmShow ? 1 : 0))) {
+              // lo pulisco
                pGraphics->Clear() ;
-            ICURVEPOVECTOR vpCurve ;
-            if ( pZmap->GetEdges( vpCurve)  &&  ! vpCurve.empty()) {
-               pGraphics->AddColor( DGRAY) ;
-               pGraphics->AddMaterial( DGRAY, DGRAY, DGRAY, 10) ;
-               pGraphics->AddBackMaterial( DGRAY) ;
-               for ( const auto& pCrv : vpCurve) {
-                  PolyLine PL ;
-                  if ( pCrv->ApproxWithLines( 10 * EPS_SMALL, ANG_TOL_GRAPH_DEG, ICurve::APL_SPECIAL, PL))
-                     pGraphics->AddPolyLine( PL, false, true) ;
+              // inserisco le curve
+               ICURVEPOVECTOR vpCurve ;
+               if ( pZmap->GetEdges( vpCurve)  &&  ! vpCurve.empty()) {
+                  pGraphics->AddColor( DGRAY) ;
+                  pGraphics->AddMaterial( DGRAY, DGRAY, DGRAY, 10) ;
+                  pGraphics->AddBackMaterial( DGRAY) ;
+                  for ( const auto& pCrv : vpCurve) {
+                     PolyLine PL ;
+                     if ( pCrv->ApproxWithLines( 10 * EPS_SMALL, ANG_TOL_GRAPH_DEG, ICurve::APL_SPECIAL, PL))
+                        pGraphics->AddPolyLine( PL, false, true) ;
+                  }
                }
             }
          }