From 9f4899148cf7c2ea203fbaf3de75acdc647a53f2 Mon Sep 17 00:00:00 2001
From: Dmitrii Kulikov <164657232+AtheneNoctuaPt@users.noreply.github.com>
Date: Mon, 15 Jun 2026 18:35:03 +0100
Subject: [PATCH] Modeling - Handle near-zero angles for coplanar faces in
 GetFaceOff function (#1312)

---
 .../TKBO/BOPTools/BOPTools_AlgoTools.cxx                  | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/ModelingAlgorithms/TKBO/BOPTools/BOPTools_AlgoTools.cxx b/src/ModelingAlgorithms/TKBO/BOPTools/BOPTools_AlgoTools.cxx
index f708a5d2d9..e6e3bb5dfa 100644
--- a/src/ModelingAlgorithms/TKBO/BOPTools/BOPTools_AlgoTools.cxx
+++ b/src/ModelingAlgorithms/TKBO/BOPTools/BOPTools_AlgoTools.cxx
@@ -1072,6 +1072,14 @@ bool BOPTools_AlgoTools::GetFaceOff(const TopoDS_Edge&                        th
       {
         aAngle = aTwoPI;
       }
+      else if (!bIsComputed)
+      {
+        // Near-zero angle between different faces where the bi-normal direction could not be
+        // reliably computed (near-degenerate geometry, e.g. very thin face producing
+        // nearly-coincident intersection curves). Treat as maximum angle (2*PI) to prevent
+        // incorrect selection of this unreliable face over a proper closing face.
+        aAngle = aTwoPI;
+      }
     }
     //
     if (std::abs(aAngle) < anAngleCriteria || std::abs(aAngle - aAngleMin) < anAngleCriteria)