Fix #3562. Non-manifold geometry is no longer considered in join criteria as there is no such thing as a closed polygon.

src/blenderbim/blenderbim/bim/module/drawing/operator.py

@@ -889,6 +889,21 @@ class CreateDrawing(bpy.types.Operator):
                 )
         return classes
 
+    def is_manifold(self, obj):
+        result = self.is_manifold_cache.get(obj.data.name, None)
+        if result is not None:
+            return result
+
+        bm = bmesh.new()
+        bm.from_mesh(obj.data)
+        for edge in bm.edges:
+            if not edge.is_manifold:
+                bm.free()
+                self.is_manifold_cache[obj.data.name] = False
+                return False
+        self.is_manifold_cache[obj.data.name] = True
+        return True
+
     def merge_linework_and_add_metadata(self, root):
         join_criteria = ifcopenshell.util.element.get_pset(self.camera_element, "EPset_Drawing", "JoinCriteria")
         if join_criteria:
@@ -899,6 +914,7 @@ class CreateDrawing(bpy.types.Operator):
 
         group = root.findall(".//{http://www.w3.org/2000/svg}g")[0]
         joined_paths = {}
+        self.is_manifold_cache = {}
 
         ifc = tool.Ifc.get()
         for el in root.findall(".//{http://www.w3.org/2000/svg}g[@{http://www.ifcopenshell.org/ns}guid]"):
@@ -908,6 +924,10 @@ class CreateDrawing(bpy.types.Operator):
             classes.append("cut")
             el.set("class", " ".join(classes))
 
+            obj = tool.Ifc.get_object(element)
+            if not self.is_manifold(obj):
+                continue
+
             # An element group will contain a bunch of paths representing the
             # cut of that element. However IfcOpenShell may not correctly
             # create closed paths. We post-process all paths with shapely to