From 488bdd3ca29b97de95a802f7c9ed160f781ce71d Mon Sep 17 00:00:00 2001
From: Dario Sassi <dario.sassi@egalware.com>
Date: Mon, 13 Jul 2026 17:49:55 +0200
Subject: [PATCH] EgtGeomKernel : - correzione a calcolo Silhouette di Trimesh
 (versioni dirette dai triangoli).

---
 SurfTriMesh.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/SurfTriMesh.cpp b/SurfTriMesh.cpp
index cb7f6c0..4507228 100644
--- a/SurfTriMesh.cpp
+++ b/SurfTriMesh.cpp
@@ -1183,7 +1183,7 @@ SurfTriMesh::GetSilhouette( const Vector3d& vtDir, double dTol, POLYLINEVECTOR&
              ( ! bAllTria  &&  Tria.GetN() * vtVers > EPS_ZERO))  &&
            Tria.Scale( frOCS, 1, 1, 0)  &&  Tria.GetSqMinHeight() > SQ_EPS_SMALL) {
          PtrOwner<SurfFlatRegion> pSfrTria( GetBasicSurfFlatRegion( GetSurfFlatRegionFromTriangle( Tria))) ;
-         if ( ! IsNull( pSfrTria)) {
+         if ( ! IsNull( pSfrTria)  &&  pSfrTria->IsValid()) {
             if ( bAllTria  &&  Tria.GetN() * vtVers < 0)
                pSfrTria->Invert() ;
             pSfrTria->Offset( dTol, ICurve::OFF_FILLET) ;
@@ -1261,7 +1261,7 @@ SurfTriMesh::GetSilhouette( const Plane3d& plPlane, double dTol, POLYLINEVECTOR&
            // lo proietto sul piano e creo la regione
             if ( pgTria.Scale( frOCS, 1, 1, 0)) {
                PtrOwner<SurfFlatRegion> pSfrTria( GetBasicSurfFlatRegion( GetSurfFlatRegionFromPolyLine( pgTria.GetPolyLine()))) ;
-               if ( ! IsNull( pSfrTria)) {
+               if ( ! IsNull( pSfrTria)  &&  pSfrTria->IsValid()) {
                   if ( bAllTria  &&  Tria.GetN() * vtVers < 0)
                      pSfrTria->Invert() ;
                   pSfrTria->Offset( dTol, ICurve::OFF_FILLET) ;