From be9ffa7322eb6823a05bbd57284be4cb66363afe Mon Sep 17 00:00:00 2001
From: Thomas Krijnen <t.krijnen@gmail.com>
Date: Mon, 17 Sep 2018 14:59:15 +0200
Subject: [PATCH] Fail early on duplicate (non consecutive) points in face
 loops

---
 src/ifcgeom/IfcGeomFunctions.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/ifcgeom/IfcGeomFunctions.cpp b/src/ifcgeom/IfcGeomFunctions.cpp
index a344d03526..9cc7f89b09 100644
--- a/src/ifcgeom/IfcGeomFunctions.cpp
+++ b/src/ifcgeom/IfcGeomFunctions.cpp
@@ -2921,6 +2921,15 @@ bool IfcGeom::Kernel::wire_intersections(const TopoDS_Wire& wire, TopTools_ListO
 			tree.add(edge_idx++, exp.Current());
 		}
 	}
+
+	if (wd->NbEdges() != n) {
+		// If the number of edges differs, BRepTools_WireExplorer did not
+		// reach every edge, probably due to loops exactly at vertex locations.
+		// This is not supported by this algorithm which only elimates loops
+		// due to edge crossings.
+
+		throw geometry_exception("Invalid loop");
+	}
 	
 	bool intersected = false;