diff --git a/EgtGraphics.rc b/EgtGraphics.rc
index 1677f1c..2a12b9d 100644
Binary files a/EgtGraphics.rc and b/EgtGraphics.rc differ
diff --git a/Scene.h b/Scene.h
index c92b91f..b3fe89f 100644
--- a/Scene.h
+++ b/Scene.h
@@ -23,6 +23,7 @@ class IGdbIterator ;
 class ICurve ;
 class ICurveComposite ;
 class ISurfTriMesh ;
+class ISurfFlatRegion ;
 class IExtText ;
 class ObjEGrGraphics ;
 
@@ -232,6 +233,8 @@ class Scene : public IEGrScene
                                     const ICurveComposite* pCrvCompo, double& dMinSqDist) ;
       bool FindSurfTMSnapPoint( int nSnap, const Point3d& ptWin, int nId, const Frame3d& frEnt,
                                 const ISurfTriMesh* pStm, double& dMinSqDist) ;
+      bool FindSurfFRSnapPoint( int nSnap, const Point3d& ptWin, int nId, const Frame3d& frEnt,
+                                const ISurfFlatRegion* pSfr, double& dMinSqDist) ;
       bool FindTextSnapPoint( int nSnap, const Point3d& ptWin, int nId, const Frame3d& frEnt,
                               const IExtText* pTxt, double& dMinSqDist) ;
 
diff --git a/SceneSnap.cpp b/SceneSnap.cpp
index 89a9798..225c3b4 100644
--- a/SceneSnap.cpp
+++ b/SceneSnap.cpp
@@ -24,6 +24,7 @@
 #include "/EgtDev/Include/EGkCurveComposite.h"
 #include "/EgtDev/Include/EGkDistPointCurve.h"
 #include "/EgtDev/Include/EGkSurfTriMesh.h"
+#include "/EgtDev/Include/EGkSurfFlatRegion.h"
 #include "/EgtDev/Include/EGkExtText.h"
 #include "/EgtDev/Include/EgkIntersCurves.h"
 #include "/EgtDev/Include/EGkIntersLineSurfTm.h"
@@ -328,6 +329,14 @@ Scene::FindSelectedSnapPoint( int nSnap, const Point3d& ptWin, int nW, int nH)
          if ( FindSurfTMSnapPoint( nSnap, ptWin, nId, frEnt, pStm, dMinSqDist))
             bFound = true ;
       }
+     // se superficie flat region
+      else if ( pGObj->GetType() == SRF_FLATRGN) {
+        // recupero la superficie
+         const ISurfFlatRegion* pSfr = GetSurfFlatRegion( pGObj) ;
+        // verifico i punti notevoli della regione
+         if ( FindSurfFRSnapPoint( nSnap, ptWin, nId, frEnt, pSfr, dMinSqDist))
+            bFound = true ;
+      }
      // se testo
       else if ( pGObj->GetType() == EXT_TEXT) {
         // recupero il testo
@@ -768,6 +777,102 @@ Scene::FindSurfTMSnapPoint( int nSnap, const Point3d& ptWin, int nId, const Fram
    return bFound ;
 }
 
+//----------------------------------------------------------------------------
+bool
+Scene::FindSurfFRSnapPoint( int nSnap, const Point3d& ptWin, int nId, const Frame3d& frEnt,
+                            const ISurfFlatRegion* pSfr, double& dMinSqDist)
+{
+  // il punto di riferimento deriva da XY su viewport e Z minima (più vicina a osservatore) da selezione 
+   Point3d ptWinZ( ptWin.x, ptWin.y, GetSelectedObjMinWinZ()) ;
+  // punto di riferimento nello spazio geometrico 3d
+   Point3d ptRef ;
+   if ( ! UnProject( ptWinZ, ptRef))
+      return false ;
+   // porto il punto nel riferimento della superficie
+   ptRef.ToLoc( frEnt) ;
+  // recupero la direzione di mira e la porto nel riferimento della superficie
+   Vector3d vtDir = - m_vtDirCamera ;
+   vtDir.ToLoc( frEnt) ;
+
+  // determino se oggetto trasparente
+   Color cCol ;
+   bool bAlpha = ( m_pGeomDB->GetCalcMaterial( nId, cCol) && cCol.GetIntAlpha() <= ALPHA_LIM) ; 
+
+  // se richiesto il centro di gravità (baricentro, centroide)
+   if ( nSnap == SP_CENTROID) {
+      Point3d ptP ;
+      bool bFound = false ;
+      if ( pSfr->GetCentroid( ptP)) {
+        // il punto di confronto è quello sulla linea di mira a minima distanza dal centro
+         Point3d ptCfr = ptRef + (( ptP - ptRef) * vtDir) * vtDir ;
+        // determino la distanza e la confronto con il minimo
+         double dSqDist = SqDist( ptP, ptCfr) ;
+         if ( dSqDist < dMinSqDist) {
+            bFound = true ;
+            dMinSqDist = dSqDist ;
+            m_nLastSnapId = nId ;
+            m_ptLastSnapPnt = ptP ;
+            m_ptLastSnapPnt.ToGlob( frEnt) ;
+            m_bLastSnapDirOk = false ;
+         }
+      }
+     // se trovato e modalità shading o hiddenline, la favorisco perchè davanti alle possibili successive
+      if ( bFound  &&  ! ( bAlpha || m_nShowMode == SM_WIREFRAME))
+         dMinSqDist = 0 ;
+      return bFound ;
+   }
+  // se richiesto il centro (è il centroide del chunk più vicino)
+   else if ( nSnap == SP_CENTER) {
+      Point3d ptP ;
+      bool bFound = false ;
+      for ( int i = 0 ; i < pSfr->GetChunkCount() ; ++ i) {
+         if ( pSfr->GetChunkCentroid( i, ptP)) {
+           // il punto di confronto è quello sulla linea di mira a minima distanza dal centro
+            Point3d ptCfr = ptRef + (( ptP - ptRef) * vtDir) * vtDir ;
+           // determino la distanza e la confronto con il minimo
+            double dSqDist = SqDist( ptP, ptCfr) ;
+            if ( dSqDist < dMinSqDist) {
+               bFound = true ;
+               dMinSqDist = dSqDist ;
+               m_nLastSnapId = nId ;
+               m_ptLastSnapPnt = ptP ;
+               m_ptLastSnapPnt.ToGlob( frEnt) ;
+               m_bLastSnapDirOk = false ;
+            }
+         }
+      }
+     // se trovato e modalità shading o hiddenline, la favorisco perchè davanti alle possibili successive
+      if ( bFound  &&  ! ( bAlpha || m_nShowMode == SM_WIREFRAME))
+         dMinSqDist = 0 ;
+      return bFound ;
+   }
+
+  // cerco sui contorni della regione
+   bool bFound = false ;
+   for ( int i = 0 ; i < pSfr->GetChunkCount() ; ++ i) {
+      for ( int j = 0 ; j < pSfr->GetLoopCount( i) ; ++ j) {
+         ICurve* pCrv = pSfr->GetLoop( i, j) ;
+         if ( pCrv == nullptr)
+            return false ;
+         if ( pCrv->GetType() == CRV_COMPO) {
+            ICurveComposite* pCrvCompo = GetCurveComposite( pCrv) ;
+            if ( FindCurveCompoSnapPoint( nSnap, ptWin, nId, frEnt, pCrvCompo, dMinSqDist))
+               bFound = true ;
+         }
+         else {
+            if ( FindCurveSnapPoint( nSnap, ptWin, nId, frEnt, pCrv, dMinSqDist))
+               bFound = true ;
+         }
+      }
+   }
+
+  // se trovato e modalità shading o hiddenline, la favorisco perchè davanti alle possibili successive
+   if ( bFound  &&  ! ( bAlpha || m_nShowMode == SM_WIREFRAME))
+      dMinSqDist = 0 ;
+
+   return bFound ;
+}
+
 //----------------------------------------------------------------------------
 bool
 Scene::FindTextSnapPoint( int nSnap, const Point3d& ptWin, int nId, const Frame3d& frEnt,