From c1a291297075b566fc7aa63450464e5c22713e85 Mon Sep 17 00:00:00 2001
From: Daniele Bariletti <daniele.bariletti@egalware.com>
Date: Thu, 25 Jun 2026 15:26:00 +0200
Subject: [PATCH] EgtGeomKernel : - correzioni e migliorie a offset3d e
 surfextend.

---
 OffsetCurve3d.cpp    |  2 +-
 ProjectCurveSurf.cpp | 34 +++++++++++++++++++++++++++++-----
 StmFromCurves.cpp    | 39 +++++++++++++++++++++++++++++++++++----
 3 files changed, 65 insertions(+), 10 deletions(-)

diff --git a/OffsetCurve3d.cpp b/OffsetCurve3d.cpp
index 54f78da..ed7801e 100644
--- a/OffsetCurve3d.cpp
+++ b/OffsetCurve3d.cpp
@@ -231,7 +231,7 @@ OffsetCurve3d::Make( const PNT5AXVECTOR& vPnt5Ax, double dOffDist, int nType)
       if ( vtDirPrevOff.IsValid())
          dProj = vtDirCurrOff * vtDirPrevOff ;
       // prima di inserirlo controllo che il tratto non torni indietro
-      if ( dProj > - 0.5  ||  vFlag[i] == OffsetCurve3d::AngType::ANG_SMOOTH_CONC) {
+      if ( vFlag[i] != ANG_STR  ||  dProj > - 0.5) {
          // aggiungo tratto
          ICurveLine* pCL = CreateBasicCurveLine() ;
          pCL->Set( ptPrev, ptP) ;
diff --git a/ProjectCurveSurf.cpp b/ProjectCurveSurf.cpp
index f767a8c..7383155 100644
--- a/ProjectCurveSurf.cpp
+++ b/ProjectCurveSurf.cpp
@@ -405,27 +405,51 @@ ProjectCurveOnSurf( const ICurve& crCrv, const CISURFPVECTOR& vpSurf,
       vtDirPrev = pt2 - pt1 ;
    }
    bool bFound = PL.GetFirstULine( &dPar, &ptP, &dParNext, &ptPNext) ;
-   Vector3d vtFirst = ptPNext - ptP ;
+   Vector3d vtFirst = ptPNext - ptP ; vtFirst.Normalize() ;
    bool bClosed = PL.IsClosed() ;
    bool bLast = false ;
+   Vector3d vtNormPrev = V_INVALID ;
    while ( bFound) {
      // se trovo proiezione, la salvo
       Point5ax Pt5ax ; 
       if ( ProjectPointOnSurf( ptP, vpSurf, dPar, Pt5ax))
          vPt5ax.emplace_back( Pt5ax) ;
+      // controllo che la normale trovata sia in linea con la precedente, se i due tratti erano abbastanza allineati
+      if ( ! bClosed  &&  ssize( vPt5ax) > 2) {
+         Point5ax& pt5Curr = vPt5ax.back() ;
+         Point5ax& pt5Prev = vPt5ax.end()[-2] ;
+         Point5ax& pt5PrevPrev = vPt5ax.end()[-3] ;
+         Vector3d vtDirCurr = pt5Curr.ptP - pt5Prev.ptP ; vtDirCurr.Normalize() ;
+         Vector3d vtDirPrev = pt5Prev.ptP - pt5PrevPrev.ptP ; vtDirPrev.Normalize() ;
+         double dProjDir = vtDirCurr * vtDirPrev ;
+         if ( dProjDir > COS_ANG_MAX_CORNER) {
+            double dProjNorm = vPt5ax.back().vtDir1 * vtNormPrev ;
+            if ( dProjNorm < COS_ANG_MAX_CORNER) {
+               vPt5ax.back().vtDir1 = vtNormPrev ;
+               vPt5ax.back().vtDir2 = vtNormPrev ;
+            }
+         }
+      }
+      vtNormPrev = vPt5ax.back().vtDir1 ;
       // se richiesta la tangente anziché la normale allora modifico il vettore associato al punto
       Vector3d vtDir ;
       if ( ! bNormOrTang) {
          Vector3d vtNorm = vPt5ax.back().vtDir1 ;
-         if ( ! bLast)
+         if ( ! bLast) {
             vtDir = ptPNext - ptP ;
+            vtDir.Normalize() ;
+         }
          else if ( bClosed)
             vtDir = vtFirst ;
          else
             vtDir = vtDirPrev ;
-         vtDirPrev = vtDir ;
-         if ( vtDirPrev.IsValid())
-            vtDir = Media( vtDir, vtDirPrev) ;
+         Vector3d vtDirTemp = vtDir ;
+         if ( vtDirPrev.IsValid()) {
+            double dProj = vtDir * vtDirPrev ;
+            if ( dProj > COS_ANG_MAX_CORNER)
+               vtDir = Media( vtDir, vtDirPrev) ;
+         }
+         vtDirPrev = vtDirTemp ;
          Vector3d vtTang = vtDir ^ vtNorm ; vtTang.Normalize() ;
          vPt5ax.back().vtDir1 = vtTang ;
          vPt5ax.back().vtDir2 = vtTang ;
diff --git a/StmFromCurves.cpp b/StmFromCurves.cpp
index ccad9ef..d07e736 100644
--- a/StmFromCurves.cpp
+++ b/StmFromCurves.cpp
@@ -2168,8 +2168,39 @@ GetSurfExtension( const ISurfTriMesh* pSrfTM, double dExtLen, int nLoop, int nSu
    PtrOwner<ICurve> pEdge ;
    if ( nSubCrv == - 1)
       pEdge.Set( pLoop) ;
-   else
-      pEdge.Set( pLoop->GetCurve( nSubCrv)->Clone()) ;
+   else {
+      // prendo tutti i lati adiacenti a quello selezionato e che non formano angoli superiori al limite
+      double dCosMin = 0.866 ;  // 30 gradi
+      // scorro in avanti
+      int nNextCrv = nSubCrv ;
+      double dProj = 1 ;
+      while ( nNextCrv < pLoop->GetCurveCount() - 1) {
+         const ICurve* pCurr = pLoop->GetCurve( nNextCrv) ;
+         const ICurve* pNext = pLoop->GetCurve( nNextCrv + 1) ;
+         Vector3d vtCurr ; pCurr->GetEndDir( vtCurr) ;
+         Vector3d vtNext ; pNext->GetStartDir( vtNext) ;
+         dProj = vtCurr * vtNext ;
+         if ( dProj > dCosMin)
+            ++ nNextCrv ;
+         else
+            break ;
+      }
+      // scorro indietro
+      int nPrevCrv = nSubCrv ;
+      dProj = 1 ;
+      while ( nPrevCrv > 1) {
+         const ICurve* pCurr = pLoop->GetCurve( nPrevCrv) ;
+         const ICurve* pPrev = pLoop->GetCurve( nPrevCrv - 1) ;
+         Vector3d vtCurr ; pCurr->GetStartDir( vtCurr) ;
+         Vector3d vtPrev ; pPrev->GetEndDir( vtPrev) ;
+         dProj = vtCurr * vtPrev ;
+         if ( dProj > dCosMin)
+            -- nPrevCrv ;
+         else
+            break ;
+      }
+      pEdge.Set( pLoop->CopyParamRange( nPrevCrv, nNextCrv + 1)) ;
+   }
 
    double dMaxLen = 2.5 ;
    PNT5AXVECTOR vPnt5Ax ;
@@ -2219,9 +2250,9 @@ GetSurfExtension( const ISurfTriMesh* pSrfTM, double dExtLen, int nLoop, int nSu
    vvGeo.back().push_back( pOffEdge->Clone()) ;
    vCol.push_back( AQUA) ;
    vvGeo.emplace_back() ;
-   for ( int i = 0 ; i < ssize( vOffDir) ; ++i) {
+   for ( int i = 0 ; i < ssize( vPnt5Ax) ; ++i) {
       IGeoVector3d* pGV = CreateGeoVector3d() ;
-      pGV->Set( vOffDir[i] * dExtLen, vPnt5Ax[i].ptP) ;
+      pGV->Set( vPnt5Ax[i].vtDir1 * dExtLen, vPnt5Ax[i].ptP) ;
       vvGeo.back().push_back( pGV) ;
    }
    vCol.push_back( LIME) ;