From: jfa <jfa@opencascade.com>
Date: Thu, 23 Jun 2022 12:08:30 +0000 (+0300)
Subject: Avoid infinite loop, found with test NRT_GRIDS_GEOM_BUG15_R7
X-Git-Tag: V9_9_1b1~3
X-Git-Url: http://git.salome-platform.org/gitweb/?p=modules%2Fsmesh.git;a=commitdiff_plain;h=bdf698e60b1ae6c7b91f28f9fb0817f417e03ae3

Avoid infinite loop, found with test NRT_GRIDS_GEOM_BUG15_R7
---

diff --git a/src/SMESHUtils/SMESH_Delaunay.cxx b/src/SMESHUtils/SMESH_Delaunay.cxx
index 70890775c..4b1598ecc 100644
--- a/src/SMESHUtils/SMESH_Delaunay.cxx
+++ b/src/SMESHUtils/SMESH_Delaunay.cxx
@@ -191,6 +191,11 @@ const BRepMesh_Triangle* SMESH_Delaunay::FindTriangle( const gp_XY&
 
   gp_XY uv = UV.Multiplied( _scale );
 
+  // prevent infinite loop in case of numerical instability
+  // test case NRT_GRIDS_GEOM_BUGS_15_R7
+  const BRepMesh_Triangle* tria1 = 0;
+  const BRepMesh_Triangle* tria2 = tria;
+
   while ( tria )
   {
     // check if the uv is in tria
@@ -203,7 +208,9 @@ const BRepMesh_Triangle* SMESH_Delaunay::FindTriangle( const gp_XY&
     SMESH_MeshAlgos::GetBarycentricCoords( uv,
                                            nodeUVs[0], nodeUVs[1], nodeUVs[2],
                                            bc[0], bc[1] );
-    if ( bc[0] >= 0 && bc[1] >= 0 && bc[0] + bc[1] <= 1 )
+    if ( (bc[0] >= 0 && bc[1] >= 0 && bc[0] + bc[1] <= 1) ||
+         (tria == tria1 &&
+          bc[0] >= -1e-14 && bc[1] >= -1e-14 && bc[0] + bc[1] <= 1 + 1e-14) )
     {
       if ( _triaDS->GetNode( nodeIDs[0] ).Movability() != BRepMesh_Frontier ||
            _triaDS->GetNode( nodeIDs[1] ).Movability() != BRepMesh_Frontier ||
@@ -218,6 +225,10 @@ const BRepMesh_Triangle* SMESH_Delaunay::FindTriangle( const gp_XY&
       return tria;
     }
 
+    if (tria == tria1) return 0;
+    tria1 = tria2;
+    tria2 = tria;
+
     // look for a neighbor triangle, which is adjacent to a link intersected
     // by a segment( triangle center -> uv )