diff --git a/CAvToolTriangle.cpp b/CAvToolTriangle.cpp
index 1d36936..a7acf56 100644
--- a/CAvToolTriangle.cpp
+++ b/CAvToolTriangle.cpp
@@ -2440,12 +2440,10 @@ CAvDiskTriangle( const Point3d& ptDiskCen, const Vector3d& vtDiskAx, double dDis
      // Allontanamento dall'interno
       double dEscapeDist = max( DiskTriaInteriorEscapeDistGenMot( ptDiskCen, vtDiskAx, dDiskRad, trTria, vtMove), 0.) ;
      // Allontanamento dalla frontiera
-      Vector3d vtMoveOrt = vtMove - vtMove * vtDiskAx * vtDiskAx ;   
+      Vector3d vtMoveOrt = OrthoCompo( vtMove, vtDiskAx) ;
       vtMoveOrt.Normalize() ;
       Frame3d DiskFrame ;
-      Vector3d vtJ = vtDiskAx ^ vtMoveOrt ;
-      vtJ.Normalize() ;
-      DiskFrame.Set( ptDiskCen, vtMoveOrt, vtJ, vtDiskAx) ;
+      DiskFrame.Set( ptDiskCen, vtDiskAx, vtMoveOrt) ;
       Triangle3d trTriaLoc = trTria ;
       Vector3d vtMoveLoc = vtMove ;
       trTriaLoc.ToLoc( DiskFrame) ;
diff --git a/CalcPocketing.cpp b/CalcPocketing.cpp
index c1d8e73..eb824f7 100644
--- a/CalcPocketing.cpp
+++ b/CalcPocketing.cpp
@@ -2690,15 +2690,30 @@ IsForcedStepTrapezoid( const ICurveComposite* pCrvTrap, const PocketParams& Pock
          bForced = true ;
      // se entrambe le basi sono aperte
       else if ( vnProps[nBase] == TEMP_PROP_OPEN_EDGE  &&  vnProps[nSecondBase] == TEMP_PROP_OPEN_EDGE) {
-         const ICurve* pCrvOpenBase = pCrvTrap->GetCurve( nBase) ;
-         const ICurve* pCrvOpenSecondBase = pCrvTrap->GetCurve( nSecondBase) ;
-         if ( pCrvOpenBase == nullptr  ||  ! pCrvOpenBase->IsValid()  ||
-              pCrvOpenSecondBase == nullptr  ||  ! pCrvOpenSecondBase->IsValid())
-            return false ;
-         double dLenOpenBase ; pCrvOpenBase->GetLength( dLenOpenBase) ;
-         double dLenSecondOpenBase ; pCrvOpenSecondBase->GetLength( dLenSecondOpenBase) ;
-         bForced = ( dLenOpenBase < dDiam + 10. * EPS_SMALL  &&
-                     dLenSecondOpenBase < dDiam + 10. * EPS_SMALL) ;
+         double dLenOpen = 0. ;
+         for ( int i = 0 ; i < 4 ; ++ i) {
+            if ( i == nBase  ||  i == nSecondBase) {
+               const ICurve* pCrvOpen = pCrvTrap->GetCurve( i) ;
+               if ( pCrvOpen == nullptr  ||  ! pCrvOpen->IsValid())
+                  return false ;
+              // essendo nei casi a trapezio, ho solo segmenti
+               pCrvOpen->GetLength( dLenOpen) ;
+               Vector3d vtDir ; pCrvOpen->GetStartDir( vtDir) ;
+               vtDir *= dLenOpen ;
+               const ICurve* pCrvClosePrev = pCrvTrap->GetCurve( ( i == 0 ? 3 : i - 1)) ;
+               if ( pCrvClosePrev == nullptr  ||  ! pCrvClosePrev->IsValid())
+                  return false ;
+               const ICurve* pCrvCloseAft = pCrvTrap->GetCurve( ( i == 3 ? 0 : i + 1)) ;
+               if ( pCrvCloseAft == nullptr  ||  ! pCrvCloseAft->IsValid())
+                  return false ;
+              // essendo un trapezio queste due direzioni me le aspetto parallele tra loro
+               Vector3d vtDirPrev ; pCrvClosePrev->GetEndDir( vtDirPrev) ;
+               Vector3d vtDirAft ; pCrvCloseAft->GetStartDir( vtDirAft) ;
+               dLenOpen = min( { OrthoCompo( vtDir, vtDirPrev).Len(), OrthoCompo( vtDir, vtDirAft).Len(), dLenOpen}) ;
+               break ;
+            }
+         }
+         bForced = ( dLenOpen < dDiam + TOL_TRAPEZOID) ;
       }
      // se alternate, non forzo
       else
@@ -2724,14 +2739,14 @@ IsForcedStepTrapezoid( const ICurveComposite* pCrvTrap, const PocketParams& Pock
             const ICurve* pCrvCloseAft = pCrvTrap->GetCurve( ( i == 3 ? 0 : i + 1)) ;
             if ( pCrvCloseAft == nullptr  ||  ! pCrvCloseAft->IsValid())
                return false ;
-           // essendo un trapezio queste due direzioni me le apsetto parallele tra loro
+           // essendo un trapezio queste due direzioni me le aspetto parallele tra loro
             Vector3d vtDirPrev ; pCrvClosePrev->GetEndDir( vtDirPrev) ;
             Vector3d vtDirAft ; pCrvCloseAft->GetStartDir( vtDirAft) ;
             dLenOpen = min( { OrthoCompo( vtDir, vtDirPrev).Len(), OrthoCompo( vtDir, vtDirAft).Len(), dLenOpen}) ;
             break ;
          }
       }
-      bForced = ( dLenOpen < dDiam + 10. * EPS_SMALL) ;
+      bForced = ( dLenOpen < dDiam + TOL_TRAPEZOID) ;
    }
    break ;
   // se tutto chiuso, è forzato
diff --git a/ProjectCurveSurf.cpp b/ProjectCurveSurf.cpp
index 6c189f7..e403193 100644
--- a/ProjectCurveSurf.cpp
+++ b/ProjectCurveSurf.cpp
@@ -393,7 +393,7 @@ typedef std::vector<IntersParLinesSurfTm*> INTPARLINESTMPVECTOR ;
 //----------------------------------------------------------------------------
 static bool
 ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const Frame3d& frRefLine, const INTPARLINESTMPVECTOR& vpIntPLSTM,
-                    double dPar, Point5ax& Pt5ax)
+                    double dPar, bool bFromVsTo, Point5ax& Pt5ax)
 {
   // intersezione retta di proiezione con superfici  (conservo l'intersezione più alta)
    Point3d ptL = GetToLoc( ptP, frRefLine) ;
@@ -402,23 +402,48 @@ ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const Frame
    for ( int i = 0 ; i < ssize( vpIntPLSTM) ; ++ i) {
       ILSIVECTOR vIntRes ;
       if ( vpIntPLSTM[i]->GetInters( ptL, 1, vIntRes, false)) {
-        // cerco la prima intersezione valida a partire dall'ultima (è la più alta)
-         int nI = ssize( vIntRes) - 1 ;
-         while ( nI >= 0  &&  abs( vIntRes[nI].dCosDN) < COS_ANG_LIM)
-            --nI ;
-        // se trovata
-         if ( nI >= 0) {
-            if ( nInd < 0) {
-               IntRes = vIntRes[nI] ;
-               nInd = i ;
-            }
-            else {
-               double dUref = (( IntRes.nILTT == ILTT_SEGM || IntRes.nILTT == ILTT_SEGM_ON_EDGE) ? IntRes.dU2 : IntRes.dU) ;
-               double dU = (( vIntRes[nI].nILTT == ILTT_SEGM || vIntRes[nI].nILTT == ILTT_SEGM_ON_EDGE) ? vIntRes[nI].dU2 : vIntRes[nI].dU) ;
-               if ( dU > dUref) {
+        // se dalla direzione
+         if ( bFromVsTo) {
+           // cerco la prima intersezione valida a partire dall'ultima (è la più alta)
+            int nI = ssize( vIntRes) - 1 ;
+            while ( nI >= 0  &&  abs( vIntRes[nI].dCosDN) < COS_ANG_LIM)
+               --nI ;
+           // se trovata
+            if ( nI >= 0) {
+               if ( nInd < 0) {
                   IntRes = vIntRes[nI] ;
                   nInd = i ;
                }
+               else {
+                  double dUref = (( IntRes.nILTT == ILTT_SEGM || IntRes.nILTT == ILTT_SEGM_ON_EDGE) ? IntRes.dU2 : IntRes.dU) ;
+                  double dU = (( vIntRes[nI].nILTT == ILTT_SEGM || vIntRes[nI].nILTT == ILTT_SEGM_ON_EDGE) ? vIntRes[nI].dU2 : vIntRes[nI].dU) ;
+                  if ( dU > dUref) {
+                     IntRes = vIntRes[nI] ;
+                     nInd = i ;
+                  }
+               }
+            }
+         }
+        // altrimenti verso la direzione
+         else {
+           // cerco la prima intersezione valida a partire dalla prima (è la più alta)
+            int nI = 0 ;
+            while ( nI < ssize( vIntRes)  &&  abs( vIntRes[nI].dCosDN) < COS_ANG_LIM)
+               ++nI ;
+           // se trovata
+            if ( nI < ssize( vIntRes)) {
+               if ( nInd < 0) {
+                  IntRes = vIntRes[nI] ;
+                  nInd = i ;
+               }
+               else {
+                  double dUref = (( IntRes.nILTT == ILTT_SEGM || IntRes.nILTT == ILTT_SEGM_ON_EDGE) ? IntRes.dU : IntRes.dU2) ;
+                  double dU = (( vIntRes[nI].nILTT == ILTT_SEGM || vIntRes[nI].nILTT == ILTT_SEGM_ON_EDGE) ? vIntRes[nI].dU : vIntRes[nI].dU2) ;
+                  if ( dU < dUref) {
+                     IntRes = vIntRes[nI] ;
+                     nInd = i ;
+                  }
+               }
             }
          }
       }
@@ -455,7 +480,7 @@ ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const Frame
 //----------------------------------------------------------------------------
 bool
 ProjectCurveOnSurf( const ICurve& crCrv, const CISURFPVECTOR& vpSurf, const Vector3d& vtDir,
-                    double dLinTol, double dMaxSegmLen, bool bSharpEdges, PNT5AXVECTOR& vPt5ax)
+                    double dLinTol, double dMaxSegmLen, bool bSharpEdges, bool bFromVsTo, PNT5AXVECTOR& vPt5ax)
 {
   // sistemazioni per tipo di superficie
    CISRFTMPVECTOR vpSurfTm ;
@@ -521,7 +546,7 @@ ProjectCurveOnSurf( const ICurve& crCrv, const CISURFPVECTOR& vpSurf, const Vect
    while ( bFound) {
      // se trovo proiezione, la salvo
       Point5ax Pt5ax ; 
-      if ( ProjectPointOnSurf( ptP, vpSurfTm, frRefLine, vpIntPLSTM, dPar, Pt5ax))
+      if ( ProjectPointOnSurf( ptP, vpSurfTm, frRefLine, vpIntPLSTM, dPar, bFromVsTo, Pt5ax))
          vPt5ax.emplace_back( Pt5ax) ;
      // passo al successivo
       bFound = PL.GetNextUPoint( &dPar, &ptP) ;
@@ -543,7 +568,8 @@ ProjectCurveOnSurf( const ICurve& crCrv, const CISURFPVECTOR& vpSurf, const Vect
 
 //----------------------------------------------------------------------------
 static bool
-ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const IGeoPoint3d& gpRef, double dPar, Point5ax& Pt5ax)
+ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const IGeoPoint3d& gpRef, double dPar, bool bFromVsTo,
+                    Point5ax& Pt5ax)
 {
   // punto di riferimento
    Point3d ptMin = gpRef.GetPoint() ;
@@ -558,23 +584,48 @@ ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const IGeoP
       for ( int i = 0 ; i < ssize( vpStm) ; ++ i) {
          ILSIVECTOR vIntRes ;
          if ( IntersLineSurfTm( ptP, vtLine, dLineLen, *vpStm[i], vIntRes, false)) {
-           // cerco la prima intersezione valida a partire dall'ultima (è la più alta)
-            int nI = ssize( vIntRes) - 1 ;
-            while ( nI >= 0  &&  abs( vIntRes[nI].dCosDN) < COS_ANG_LIM)
-               --nI ;
-           // se trovata
-            if ( nI >= 0) {
-               if ( nInd < 0) {
-                  IntRes = vIntRes[nI] ;
-                  nInd = i ;
-               }
-               else {
-                  double dUref = (( IntRes.nILTT == ILTT_SEGM || IntRes.nILTT == ILTT_SEGM_ON_EDGE) ? IntRes.dU2 : IntRes.dU) ;
-                  double dU = (( vIntRes[nI].nILTT == ILTT_SEGM || vIntRes[nI].nILTT == ILTT_SEGM_ON_EDGE) ? vIntRes[nI].dU2 : vIntRes[nI].dU) ;
-                  if ( dU > dUref) {
+            // se dal punto
+            if ( bFromVsTo) {
+              // cerco la prima intersezione valida a partire dall'ultima (è la più alta)
+               int nI = ssize( vIntRes) - 1 ;
+               while ( nI >= 0  &&  abs( vIntRes[nI].dCosDN) < COS_ANG_LIM)
+                  --nI ;
+              // se trovata
+               if ( nI >= 0) {
+                  if ( nInd < 0) {
                      IntRes = vIntRes[nI] ;
                      nInd = i ;
                   }
+                  else {
+                     double dUref = (( IntRes.nILTT == ILTT_SEGM || IntRes.nILTT == ILTT_SEGM_ON_EDGE) ? IntRes.dU2 : IntRes.dU) ;
+                     double dU = (( vIntRes[nI].nILTT == ILTT_SEGM || vIntRes[nI].nILTT == ILTT_SEGM_ON_EDGE) ? vIntRes[nI].dU2 : vIntRes[nI].dU) ;
+                     if ( dU > dUref) {
+                        IntRes = vIntRes[nI] ;
+                        nInd = i ;
+                     }
+                  }
+               }
+            }
+           // altrimenti verso il punto
+            else {
+              // cerco la prima intersezione valida a partire dalla prima (è la più alta)
+               int nI = 0 ;
+               while ( nI < ssize( vIntRes)  &&  abs( vIntRes[nI].dCosDN) < COS_ANG_LIM)
+                  ++nI ;
+              // se trovata
+               if ( nI < ssize( vIntRes)) {
+                  if ( nInd < 0) {
+                     IntRes = vIntRes[nI] ;
+                     nInd = i ;
+                  }
+                  else {
+                     double dUref = (( IntRes.nILTT == ILTT_SEGM || IntRes.nILTT == ILTT_SEGM_ON_EDGE) ? IntRes.dU : IntRes.dU2) ;
+                     double dU = (( vIntRes[nI].nILTT == ILTT_SEGM || vIntRes[nI].nILTT == ILTT_SEGM_ON_EDGE) ? vIntRes[nI].dU : vIntRes[nI].dU2) ;
+                     if ( dU < dUref) {
+                        IntRes = vIntRes[nI] ;
+                        nInd = i ;
+                     }
+                  }
                }
             }
          }
@@ -612,7 +663,7 @@ ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const IGeoP
 //----------------------------------------------------------------------------
 bool
 ProjectCurveOnSurf( const ICurve& crCrv, const CISURFPVECTOR& vpSurf, const IGeoPoint3d& gpRef,
-                    double dLinTol, double dMaxSegmLen, bool bSharpEdges, PNT5AXVECTOR& vPt5ax)
+                    double dLinTol, double dMaxSegmLen, bool bSharpEdges, bool bFromVsTo, PNT5AXVECTOR& vPt5ax)
 {
   // sistemazioni per tipo di superficie
    CISRFTMPVECTOR vpSurfTm ;
@@ -663,7 +714,7 @@ ProjectCurveOnSurf( const ICurve& crCrv, const CISURFPVECTOR& vpSurf, const IGeo
    while ( bFound) {
      // se trovo proiezione, la salvo
       Point5ax Pt5ax ; 
-      if ( ProjectPointOnSurf( ptP, vpSurfTm, gpRef, dPar, Pt5ax))
+      if ( ProjectPointOnSurf( ptP, vpSurfTm, gpRef, dPar, bFromVsTo, Pt5ax))
          vPt5ax.emplace_back( Pt5ax) ;
      // passo al successivo
       bFound = PL.GetNextUPoint( &dPar, &ptP) ;
@@ -681,7 +732,8 @@ ProjectCurveOnSurf( const ICurve& crCrv, const CISURFPVECTOR& vpSurf, const IGeo
 
 //----------------------------------------------------------------------------
 static bool
-ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const ICurve& crRef, double dPar, Point5ax& Pt5ax)
+ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const ICurve& crRef, double dPar, bool bFromVsTo,
+                    Point5ax& Pt5ax)
 {
   // punto a minima distanza
    DistPointCurve dPC( ptP, crRef) ;
@@ -699,23 +751,48 @@ ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const ICurv
          for ( int i = 0 ; i < ssize( vpStm) ; ++ i) {
             ILSIVECTOR vIntRes ;
             if ( IntersLineSurfTm( ptP, vtLine, dLineLen, *vpStm[i], vIntRes, false)) {
-              // cerco la prima intersezione valida a partire dall'ultima (è la più alta)
-               int nI = ssize( vIntRes) - 1 ;
-               while ( nI >= 0  &&  abs( vIntRes[nI].dCosDN) < COS_ANG_LIM)
-                  --nI ;
-              // se trovata
-               if ( nI >= 0) {
-                  if ( nInd < 0) {
-                     IntRes = vIntRes[nI] ;
-                     nInd = i ;
-                  }
-                  else {
-                     double dUref = (( IntRes.nILTT == ILTT_SEGM || IntRes.nILTT == ILTT_SEGM_ON_EDGE) ? IntRes.dU2 : IntRes.dU) ;
-                     double dU = (( vIntRes[nI].nILTT == ILTT_SEGM || vIntRes[nI].nILTT == ILTT_SEGM_ON_EDGE) ? vIntRes[nI].dU2 : vIntRes[nI].dU) ;
-                     if ( dU > dUref) {
+              // se dalla curva
+               if ( bFromVsTo) {
+                 // cerco la prima intersezione valida a partire dall'ultima (è la più alta)
+                  int nI = ssize( vIntRes) - 1 ;
+                  while ( nI >= 0  &&  abs( vIntRes[nI].dCosDN) < COS_ANG_LIM)
+                     --nI ;
+                 // se trovata
+                  if ( nI >= 0) {
+                     if ( nInd < 0) {
                         IntRes = vIntRes[nI] ;
                         nInd = i ;
                      }
+                     else {
+                        double dUref = (( IntRes.nILTT == ILTT_SEGM || IntRes.nILTT == ILTT_SEGM_ON_EDGE) ? IntRes.dU2 : IntRes.dU) ;
+                        double dU = (( vIntRes[nI].nILTT == ILTT_SEGM || vIntRes[nI].nILTT == ILTT_SEGM_ON_EDGE) ? vIntRes[nI].dU2 : vIntRes[nI].dU) ;
+                        if ( dU > dUref) {
+                           IntRes = vIntRes[nI] ;
+                           nInd = i ;
+                        }
+                     }
+                  }
+               }
+              // altrimenti verso la curva
+               else {
+                 // cerco la prima intersezione valida a partire dalla prima (è la più alta)
+                  int nI = 0 ;
+                  while ( nI < ssize( vIntRes)  &&  abs( vIntRes[nI].dCosDN) < COS_ANG_LIM)
+                     ++nI ;
+                 // se trovata
+                  if ( nI < ssize( vIntRes)) {
+                     if ( nInd < 0) {
+                        IntRes = vIntRes[nI] ;
+                        nInd = i ;
+                     }
+                     else {
+                        double dUref = (( IntRes.nILTT == ILTT_SEGM || IntRes.nILTT == ILTT_SEGM_ON_EDGE) ? IntRes.dU : IntRes.dU2) ;
+                        double dU = (( vIntRes[nI].nILTT == ILTT_SEGM || vIntRes[nI].nILTT == ILTT_SEGM_ON_EDGE) ? vIntRes[nI].dU : vIntRes[nI].dU2) ;
+                        if ( dU < dUref) {
+                           IntRes = vIntRes[nI] ;
+                           nInd = i ;
+                        }
+                     }
                   }
                }
             }
@@ -738,7 +815,7 @@ ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const ICurv
            // assegno valori al punto 5assi
             Pt5ax.ptP = ptInt ;
             Pt5ax.vtDir1 = vtN ;
-            Pt5ax.vtDir2 = vtLine ;
+            Pt5ax.vtDir2 = ( bFromVsTo ? vtLine : -vtLine) ;
             Pt5ax.vtDirU = V_NULL ;
             Pt5ax.vtDirV = V_NULL ;
             Pt5ax.dPar = dPar ;
@@ -754,7 +831,7 @@ ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const ICurv
 //----------------------------------------------------------------------------
 bool
 ProjectCurveOnSurf( const ICurve& crCrv, const CISURFPVECTOR& vpSurf, const ICurve& crRef,
-                    double dLinTol, double dMaxSegmLen, bool bSharpEdges, PNT5AXVECTOR& vPt5ax)
+                    double dLinTol, double dMaxSegmLen, bool bSharpEdges, bool bFromVsTo, PNT5AXVECTOR& vPt5ax)
 {
   // Sistemazioni per tipo di superficie
    CISRFTMPVECTOR vpSurfTm ;
@@ -805,7 +882,7 @@ ProjectCurveOnSurf( const ICurve& crCrv, const CISURFPVECTOR& vpSurf, const ICur
    while ( bFound) {
      // se trovo proiezione, la salvo
       Point5ax Pt5ax ; 
-      if ( ProjectPointOnSurf( ptP, vpSurfTm, crRef, dPar, Pt5ax))
+      if ( ProjectPointOnSurf( ptP, vpSurfTm, crRef, dPar, bFromVsTo, Pt5ax))
          vPt5ax.emplace_back( Pt5ax) ;
      // passo al successivo
       bFound = PL.GetNextUPoint( &dPar, &ptP) ;
@@ -823,7 +900,8 @@ ProjectCurveOnSurf( const ICurve& crCrv, const CISURFPVECTOR& vpSurf, const ICur
 
 //----------------------------------------------------------------------------
 static bool
-ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const SurfTriMesh& stmRef, double dPar, Point5ax& Pt5ax)
+ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const SurfTriMesh& stmRef, double dPar, bool bFromVsTo,
+                    Point5ax& Pt5ax)
 {
   // punto sulla superficie guida a minima distanza
    DistPointSurfTm dPS( ptP, stmRef) ;
@@ -850,23 +928,48 @@ ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const SurfT
       for ( int i = 0 ; i < ssize( vpStm) ; ++ i) {
          ILSIVECTOR vIntRes ;
          if ( IntersLineSurfTm( ptP, vtLine, dLineLen, *vpStm[i], vIntRes, false)) {
-           // cerco la prima intersezione valida a partire dall'ultima (è la più alta)
-            int nI = ssize( vIntRes) - 1 ;
-            while ( nI >= 0  &&  abs( vIntRes[nI].dCosDN) < COS_ANG_LIM)
-               --nI ;
-           // se trovata
-            if ( nI >= 0) {
-               if ( nInd < 0) {
-                  IntRes = vIntRes[nI] ;
-                  nInd = i ;
-               }
-               else {
-                  double dUref = (( IntRes.nILTT == ILTT_SEGM || IntRes.nILTT == ILTT_SEGM_ON_EDGE) ? IntRes.dU2 : IntRes.dU) ;
-                  double dU = (( vIntRes[nI].nILTT == ILTT_SEGM || vIntRes[nI].nILTT == ILTT_SEGM_ON_EDGE) ? vIntRes[nI].dU2 : vIntRes[nI].dU) ;
-                  if ( dU > dUref) {
+           // se dalla superficie
+            if ( bFromVsTo) {
+              // cerco la prima intersezione valida a partire dall'ultima (è la più alta)
+               int nI = ssize( vIntRes) - 1 ;
+               while ( nI >= 0  &&  abs( vIntRes[nI].dCosDN) < COS_ANG_LIM)
+                  --nI ;
+              // se trovata
+               if ( nI >= 0) {
+                  if ( nInd < 0) {
                      IntRes = vIntRes[nI] ;
                      nInd = i ;
                   }
+                  else {
+                     double dUref = (( IntRes.nILTT == ILTT_SEGM || IntRes.nILTT == ILTT_SEGM_ON_EDGE) ? IntRes.dU2 : IntRes.dU) ;
+                     double dU = (( vIntRes[nI].nILTT == ILTT_SEGM || vIntRes[nI].nILTT == ILTT_SEGM_ON_EDGE) ? vIntRes[nI].dU2 : vIntRes[nI].dU) ;
+                     if ( dU > dUref) {
+                        IntRes = vIntRes[nI] ;
+                        nInd = i ;
+                     }
+                  }
+               }
+            }
+           // altrimenti verso la superficie
+            else {
+              // cerco la prima intersezione valida a partire dalla prima (è la più alta)
+               int nI = 0 ;
+               while ( nI < ssize( vIntRes)  &&  abs( vIntRes[nI].dCosDN) < COS_ANG_LIM)
+                  ++nI ;
+              // se trovata
+               if ( nI < ssize( vIntRes)) {
+                  if ( nInd < 0) {
+                     IntRes = vIntRes[nI] ;
+                     nInd = i ;
+                  }
+                  else {
+                     double dUref = (( IntRes.nILTT == ILTT_SEGM || IntRes.nILTT == ILTT_SEGM_ON_EDGE) ? IntRes.dU : IntRes.dU2) ;
+                     double dU = (( vIntRes[nI].nILTT == ILTT_SEGM || vIntRes[nI].nILTT == ILTT_SEGM_ON_EDGE) ? vIntRes[nI].dU : vIntRes[nI].dU2) ;
+                     if ( dU < dUref) {
+                        IntRes = vIntRes[nI] ;
+                        nInd = i ;
+                     }
+                  }
                }
             }
          }
@@ -911,7 +1014,7 @@ ProjectPointOnSurf( const Point3d& ptP, const CISRFTMPVECTOR& vpStm, const SurfT
 //----------------------------------------------------------------------------
 bool
 ProjectCurveOnSurf( const ICurve& crCrv, const CISURFPVECTOR& vpSurf, const ISurf& sfRef,
-                    double dLinTol, double dMaxSegmLen, bool bSharpEdges, PNT5AXVECTOR& vPt5ax)
+                    double dLinTol, double dMaxSegmLen, bool bSharpEdges, bool bFromVsTo, PNT5AXVECTOR& vPt5ax)
 {
   // sistemazioni per tipo di superficie
    CISRFTMPVECTOR vpSurfTm ;
@@ -983,7 +1086,7 @@ ProjectCurveOnSurf( const ICurve& crCrv, const CISURFPVECTOR& vpSurf, const ISur
    while ( bFound) {
      // se trovo proiezione, la salvo
       Point5ax Pt5ax ; 
-      if ( ProjectPointOnSurf( ptP, vpSurfTm, *pRefTm, dPar, Pt5ax))
+      if ( ProjectPointOnSurf( ptP, vpSurfTm, *pRefTm, dPar, bFromVsTo, Pt5ax))
          vPt5ax.emplace_back( Pt5ax) ;
      // passo al successivo
       bFound = PL.GetNextUPoint( &dPar, &ptP) ;