From 229c7285c220d78cb6bb8cd50e8e5a8045652489 Mon Sep 17 00:00:00 2001
From: Dion Moult <dion@thinkmoult.com>
Date: Mon, 20 Nov 2023 16:57:19 +1100
Subject: [PATCH] Add support for loading nested elements and consider nesting
 for indirect spatial containment.

---
 src/blenderbim/blenderbim/bim/import_ifc.py   | 13 +++++++++--
 src/blenderbim/blenderbim/tool/collector.py   |  8 +++++++
 .../ifcopenshell/util/element.py              | 22 ++++++++++++++++++-
 3 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/src/blenderbim/blenderbim/bim/import_ifc.py b/src/blenderbim/blenderbim/bim/import_ifc.py
index a5d53fdef0..f6da9fc310 100644
--- a/src/blenderbim/blenderbim/bim/import_ifc.py
+++ b/src/blenderbim/blenderbim/bim/import_ifc.py
@@ -1537,7 +1537,7 @@ class IfcImporter:
     def create_collections(self):
         self.create_spatial_decomposition_collections()
         if self.ifc_import_settings.collection_mode == "DECOMPOSITION":
-            self.create_aggregate_collections()
+            self.create_aggregate_and_nest_collections()
         elif self.ifc_import_settings.collection_mode == "SPATIAL_DECOMPOSITION":
             pass
 
@@ -1573,16 +1573,22 @@ class IfcImporter:
                 for rel_aggregate in element.IsDecomposedBy:
                     self.create_spatial_decomposition_collection(collection, rel_aggregate.RelatedObjects)
 
-    def create_aggregate_collections(self):
+    def create_aggregate_and_nest_collections(self):
         if self.ifc_import_settings.has_filter:
             rel_aggregates = [e.IsDecomposedBy[0] for e in self.elements if e.IsDecomposedBy]
             rel_aggregates += [e.Decomposes[0] for e in self.elements if e.Decomposes]
+            rel_aggregates += [e.IsNestedBy[0] for e in self.elements if e.IsNestedBy]
+            rel_aggregates += [e.Nests[0] for e in self.elements if e.Nests]
             rel_aggregates = set(rel_aggregates)
         else:
             rel_aggregates = [
                 a
                 for a in self.file.by_type("IfcRelAggregates")
                 if a.RelatingObject.is_a("IfcElement") or a.RelatingObject.is_a("IfcElementType")
+            ] + [
+                a
+                for a in self.file.by_type("IfcRelNests")
+                if a.RelatingObject.is_a("IfcElement") or a.RelatingObject.is_a("IfcElementType")
             ]
 
         if len(rel_aggregates) > 10000:
@@ -1687,6 +1693,9 @@ class IfcImporter:
         elif getattr(element, "Decomposes", None):
             aggregate = ifcopenshell.util.element.get_aggregate(element)
             return self.collections[aggregate.GlobalId].objects.link(obj)
+        elif getattr(element, "Nests", None):
+            nest = ifcopenshell.util.element.get_nest(element)
+            return self.collections[nest.GlobalId].objects.link(obj)
         else:
             return self.place_object_in_spatial_decomposition_collection(element, obj)
 
diff --git a/src/blenderbim/blenderbim/tool/collector.py b/src/blenderbim/blenderbim/tool/collector.py
index 3bf150ae93..4d9a4b2705 100644
--- a/src/blenderbim/blenderbim/tool/collector.py
+++ b/src/blenderbim/blenderbim/tool/collector.py
@@ -199,6 +199,14 @@ class Collector(blenderbim.core.tool.Collector):
                 if collection:
                     return collection
 
+        nest = ifcopenshell.util.element.get_nest(element)
+        if nest:
+            nest_obj = tool.Ifc.get_object(nest)
+            if nest_obj:
+                collection = nest_obj.BIMObjectProperties.collection
+                if collection:
+                    return collection
+
         container = ifcopenshell.util.element.get_container(element)
         if container:
             container_obj = tool.Ifc.get_object(container)
diff --git a/src/ifcopenshell-python/ifcopenshell/util/element.py b/src/ifcopenshell-python/ifcopenshell/util/element.py
index 11d222d318..ca9ee2665d 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/element.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/element.py
@@ -691,6 +691,9 @@ def get_container(element, should_get_direct=False, ifc_class=None):
         aggregate = get_aggregate(element)
         if aggregate:
             return get_container(aggregate, should_get_direct)
+        nest = get_nest(element)
+        if nest:
+            return get_container(nest, should_get_direct)
         if hasattr(element, "ContainedInStructure") and element.ContainedInStructure:
             container = element.ContainedInStructure[0].RelatingStructure
             if not ifc_class:
@@ -790,7 +793,7 @@ def get_grouped_by(element):
 
 def get_aggregate(element):
     """
-    Retrieves the aggregate of an element.
+    Retrieves the aggregate parent of an element.
 
     :param element: The IFC element
     :return: The aggregate of the element
@@ -805,6 +808,23 @@ def get_aggregate(element):
         return element.Decomposes[0].RelatingObject
 
 
+def get_nest(element):
+    """
+    Retrieves the nest parent of an element.
+
+    :param element: The IFC element
+    :return: The nested whole of the element
+
+    Example:
+
+    .. code:: python
+    element = file.by_type("IfcBeam")[0]
+    aggregate = ifcopenshell.util.element.get_nest(element)
+    """
+    if hasattr(element, "Nests") and element.Nests:
+        return element.Nests[0].RelatingObject
+
+
 def get_parts(element):
     """
     Retrieves the parts of an element.