diff --git a/EXE_GdbGetSurf.cpp b/EXE_GdbGetSurf.cpp
index 8113edc..2c88ba1 100644
--- a/EXE_GdbGetSurf.cpp
+++ b/EXE_GdbGetSurf.cpp
@@ -834,7 +834,8 @@ ExeExtractSurfTmLoops( int nId, int nDestGrpId, int* pnCount)
 
 //----------------------------------------------------------------------------
 int
-ExeGetSurfTmSilhouette( int nId, const Vector3d& vtDir, double dToler, int nDestGrpId, int nRefType, int* pnCount)
+ExeGetSurfTmSilhouette( int nId, const Vector3d& vtDir, double dToler, int nDestGrpId, int nRefType,
+                        int* pnCount, bool bAllTria)
 {
    IGeomDB* pGeomDB = GetCurrGeomDB() ;
    VERIFY_GEOMDB( pGeomDB, GDB_ID_NULL)
@@ -851,7 +852,7 @@ ExeGetSurfTmSilhouette( int nId, const Vector3d& vtDir, double dToler, int nDest
    Vector3d vtDirL = GetVectorLocal( pGeomDB, vtDir, nRefType, frSurf) ;
   // recupero i loop come polilinee
    POLYLINEVECTOR vPL ;
-   bOk = bOk && pStm->GetSilhouette( vtDirL, dToler, vPL) ;
+   bOk = bOk && pStm->GetSilhouette( vtDirL, dToler, vPL, bAllTria) ;
   // dalle polilinee creo le curve e le inserisco nel DB
    int nFirstId = GDB_ID_NULL ;
    int nCount = 0 ;
@@ -879,7 +880,8 @@ ExeGetSurfTmSilhouette( int nId, const Vector3d& vtDir, double dToler, int nDest
       string sLua = "EgtGetSurfTmSilhouette(" + ToString( nId) + ",{" +
                                                 ToString( vtDir) + "}," +
                                                 ToString( nDestGrpId) + "," +
-                                                RefTypeToString( nRefType) + ")" +
+                                                RefTypeToString( nRefType) + "," +
+                                                ToString( bAllTria) + ")" +
                     " -- Id1=" + ToString( nFirstId) + ",Nbr=" + ToString( nCount) ;
       LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
    }
diff --git a/EXE_GdbModifySurf.cpp b/EXE_GdbModifySurf.cpp
index f24a13c..be40422 100644
--- a/EXE_GdbModifySurf.cpp
+++ b/EXE_GdbModifySurf.cpp
@@ -29,8 +29,10 @@
 #include "/EgtDev/Include/EGkStmFromTriangleSoup.h"
 #include "/EgtDev/Include/EGkCAvSimpleSurfFrMove.h"
 #include "/EgtDev/Include/EGkStringUtils3d.h"
+#include "/EgtDev/Include/EGkSubtractProjectedFacesOnStmFace.h"
 #include "/EgtDev/Include/EgtPointerOwner.h"
 
+
 using namespace std ;
 
 //----------------------------------------------------------------------------
@@ -924,3 +926,69 @@ ExeSurfTmCut( int nId, int nCutterId, bool bInVsOut, bool bSaveOnEq)
    }
    return bOk ;
 }
+
+//----------------------------------------------------------------------------
+bool
+ExeSubtractProjectedFacesOnStmFace( int nSurfId, int nFaceInd, int nDestGrpId,
+                                    INTVECTOR vSurfsId, INTVECTOR vSurfFacesInd, bool bOCFlag,
+                                    int& nNewId, bool& bExistProjection, int& nNewFaceNbr)
+{
+   IGeomDB* pGeomDB = GetCurrGeomDB() ;
+   VERIFY_GEOMDB( pGeomDB, false)
+  // controllo dimensione dei vettori passati come parametri
+   if ( int( vSurfsId.size()) != int( vSurfFacesInd.size()))
+      return false ;
+  // recupero la superficie TriMesh su cui proiettare
+   ISurfTriMesh* pStm = GetSurfTriMesh( pGeomDB->GetGeoObj( nSurfId)) ;
+   if ( pStm == nullptr)
+      return false ;
+  // recupero il riferimento della superficie
+   Frame3d frSurf ;
+   if ( ! pGeomDB->GetGlobFrame( nSurfId, frSurf))
+      return false ;
+  // recupero il riferimento del gruppo di destinazione
+   Frame3d frDest ;
+   if ( ! pGeomDB->GetGroupGlobFrame( nDestGrpId, frDest))
+      return false ;
+  // costruzione vettori di superfici e indici delle facce per proiezione
+   ISURFTMPOVECTOR vpStmOthers ;
+   vector<SurfLocal> vSurfCLoc ;
+  // recupero le altre superfici e le porto nel sistema di riferimento della prima
+   for ( int i = 0 ; i < int( vSurfsId.size()) ; ++ i) {
+      if ( pGeomDB->GetGeoType( vSurfsId[i]) != SRF_TRIMESH)
+         return false ;
+      vSurfCLoc.emplace_back( pGeomDB, vSurfsId[i], frSurf) ;
+      const ISurfTriMesh* pStmCurr = GetSurfTriMesh( vSurfCLoc.back().Get()) ;
+      vpStmOthers.emplace_back( pStmCurr->Clone()) ;
+   }
+  // eseguo la proiezione
+   ISurfTriMesh* pStmRes = nullptr ;
+   bool bOk = SubtractProjectedFacesOnStmFace( *pStm, nFaceInd, vpStmOthers, vSurfFacesInd, bOCFlag,
+                                               bExistProjection, pStmRes, nNewFaceNbr) ;
+   if ( ! bOk)
+      delete( pStmRes) ;
+
+   nNewId = GDB_ID_NULL ;
+   if ( bOk  &&  pStmRes != nullptr) {
+     // porto nel sistema di riferimento destinazione
+      pStmRes->LocToLoc( frSurf, frDest) ;
+     // la inserisco nel DB geometrico
+      nNewId = pGeomDB->AddGeoObj( GDB_ID_NULL, nDestGrpId, pStmRes) ;
+      if ( nNewId == GDB_ID_NULL)
+         return false ;
+      ExeSetModified() ;
+   }
+
+   if ( IsCmdLog()) {
+      string sLua = "EgtSubtractProjectedFacesOnStmFace(" + ToString( nSurfId) + "," +
+                                                            ToString( nFaceInd) + "," +
+                                                            ToString( nDestGrpId) + "," +
+                                                            ToString( vSurfsId) + "," +
+                                                            ToString( vSurfFacesInd) + "," +
+                                                            ToString( bOCFlag) + ")" +
+                    " -- Ok=" + ToString( bOk) + " Id=" + ToString( nNewId) ;
+      LOG_INFO( GetCmdLogger(), sLua.c_str()) ;
+   }
+   return bOk ;
+}
+
diff --git a/EgtExecutor.rc b/EgtExecutor.rc
index ecbd44e..067d249 100644
Binary files a/EgtExecutor.rc and b/EgtExecutor.rc differ
diff --git a/LUA_GdbGetSurf.cpp b/LUA_GdbGetSurf.cpp
index 20f347f..b8cfa0a 100644
--- a/LUA_GdbGetSurf.cpp
+++ b/LUA_GdbGetSurf.cpp
@@ -723,7 +723,7 @@ LuaExtractSurfTmLoops( lua_State* L)
 static int
 LuaGetSurfTmSilhouette( lua_State* L)
 {
-  // 4 o 5 parametri : nId, vtDir, dToler, nDestGrpId [, nRefType]
+  // 4 o 5 o 6 parametri : nId, vtDir, dToler, nDestGrpId [, nRefType] [, bAllTria]
    int nId ;
    LuaCheckParam( L, 1, nId)
    Vector3d vtDir ;
@@ -734,10 +734,12 @@ LuaGetSurfTmSilhouette( lua_State* L)
    LuaCheckParam( L, 4, nDestGrpId)
    int nRefType = RTY_DEFAULT ;
    LuaGetParam( L, 5, nRefType) ;
+   bool bAllTria = false ;
+   LuaGetParam( L, 6, bAllTria) ;
    LuaClearStack( L) ;
   // recupero i contorni della superficie
    int nCount = 0 ;
-   int nNewId = ExeGetSurfTmSilhouette( nId, vtDir, dToler, nDestGrpId, nRefType, &nCount) ;
+   int nNewId = ExeGetSurfTmSilhouette( nId, vtDir, dToler, nDestGrpId, nRefType, &nCount, bAllTria) ;
   // restituisco il risultato
    if ( nNewId != GDB_ID_NULL)
       LuaSetParam( L, nNewId) ;
diff --git a/LUA_GdbModifySurf.cpp b/LUA_GdbModifySurf.cpp
index d865e4d..23f9746 100644
--- a/LUA_GdbModifySurf.cpp
+++ b/LUA_GdbModifySurf.cpp
@@ -388,6 +388,40 @@ LuaSurfTmCut( lua_State* L)
    return 1 ;
 }
 
+//-------------------------------------------------------------------------------
+static int
+LuaSubtractProjectedFacesOnStmFace( lua_State* L)
+{
+  // 3 o 4 o 5 o 6 parametri : nSurfId, nFaceInd, nDestGrpId [, vSurfsId] [, vSurfFacesInd] [, bOCFlag]
+   int nSurfId ;
+   LuaCheckParam( L, 1, nSurfId) ;
+   int nFaceInd ;
+   LuaCheckParam( L, 2, nFaceInd) ;
+   int nDestGrpId ;
+   LuaCheckParam( L, 3, nDestGrpId) ;
+   INTVECTOR vSurfsId ; 
+   LuaGetParam( L, 4, vSurfsId) ;
+   INTVECTOR vSurfFacesInd ;
+   LuaGetParam( L, 5, vSurfFacesInd) ;
+   bool bOCFlag = true ;
+   LuaGetParam( L, 6, bOCFlag) ;
+   LuaClearStack( L) ;
+  // sottraggo alla faccia scelta la proiezione delle altre
+   int nNewId = GDB_ID_NULL;
+   bool bExistProjection = false ;
+   int nNewFaceNbr = -1 ;
+   bool bOk = ExeSubtractProjectedFacesOnStmFace( nSurfId, nFaceInd, nDestGrpId, vSurfsId, vSurfFacesInd,
+                                                  bOCFlag, nNewId, bExistProjection, nNewFaceNbr) ;
+   LuaSetParam( L, bOk) ;
+   LuaSetParam( L, bExistProjection) ;
+   LuaSetParam( L, nNewFaceNbr) ;
+   if ( nNewId != GDB_ID_NULL)
+      LuaSetParam( L, nNewId) ;
+   else
+      LuaSetParam( L) ;
+   return 4 ;
+}
+
 //-------------------------------------------------------------------------------
 bool
 LuaInstallGdbModifySurf( LuaMgr& luaMgr)
@@ -413,5 +447,6 @@ LuaInstallGdbModifySurf( LuaMgr& luaMgr)
    bOk = bOk && luaMgr.RegisterFunction( "EgtSurfTmResetTwoColors", LuaSurfTmResetTwoColors) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtSurfTmSplit", LuaSurfTmSplit) ;
    bOk = bOk && luaMgr.RegisterFunction( "EgtSurfTmCut", LuaSurfTmCut) ;
+   bOk = bOk && luaMgr.RegisterFunction( "EgtSubtractProjectedFacesOnStmFace", LuaSubtractProjectedFacesOnStmFace) ;
    return bOk ;
 }