Add api.structural.assign_product, assign_to_building, and api.geometry.add_topology_representation

assign_product creates IfcRelAssignsToProduct linking a structural member to
a physical building element. assign_to_building creates IfcRelServicesBuildings
linking a structural analysis model to a building. add_topology_representation
creates IfcTopologyRepresentation for structural elements, inferring the
representation type from the item class.

Generated with the assistance of an AI coding tool.

src/ifcopenshell-python/ifcopenshell/api/geometry/__init__.py

@@ -25,6 +25,7 @@ geometry extrusions).
 
 from .. import wrap_usecases
 from .add_axis_representation import add_axis_representation
+from .add_topology_representation import add_topology_representation
 from .add_boolean import add_boolean
 from .clip_solid import clip_solid
 from .clip_solid_bounded import clip_solid_bounded
@@ -63,6 +64,7 @@ wrap_usecases(__path__, __name__)
 
 __all__ = [
     "add_axis_representation",
+    "add_topology_representation",
     "add_boolean",
     "clip_solid",
     "clip_solid_bounded",

src/ifcopenshell-python/ifcopenshell/api/geometry/add_topology_representation.py

@@ -0,0 +1,98 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2026 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+# This file was generated with the assistance of an AI coding tool.
+
+from typing import Optional
+
+import ifcopenshell
+
+
+_ITEM_TYPE_TO_REP_TYPE = {
+    "IfcVertex": "Vertex",
+    "IfcVertexPoint": "Vertex",
+    "IfcEdge": "Edge",
+    "IfcOrientedEdge": "Edge",
+    "IfcEdgeCurve": "Edge",
+    "IfcEdgeLoop": "Edge",
+    "IfcPath": "Edge",
+    "IfcFace": "Face",
+    "IfcFaceSurface": "Face",
+    "IfcAdvancedFace": "Face",
+    "IfcClosedShell": "Face",
+    "IfcOpenShell": "Face",
+    "IfcConnectedFaceSet": "Face",
+}
+
+
+def add_topology_representation(
+    file: ifcopenshell.file,
+    context: ifcopenshell.entity_instance,
+    item: ifcopenshell.entity_instance,
+    representation_identifier: Optional[str] = None,
+    representation_type: Optional[str] = None,
+) -> ifcopenshell.entity_instance:
+    """Adds an IfcTopologyRepresentation for a structural element
+
+    Structural analysis elements (IfcStructuralSurfaceMember,
+    IfcStructuralCurveMember) use topology representations rather than solid
+    geometry. This is analogous to :func:`add_axis_representation` and
+    :func:`add_profile_representation` but produces an
+    IfcTopologyRepresentation instead of an IfcShapeRepresentation.
+
+    The representation type ("Face", "Edge", "Vertex") is inferred from the
+    item's IFC class if not provided explicitly.
+
+    :param context: The IfcGeometricRepresentationContext for the
+        representation, typically a Reference context.
+    :param item: The IfcTopologicalRepresentationItem (e.g. IfcFaceSurface,
+        IfcEdge) to include in the representation.
+    :param representation_identifier: The RepresentationIdentifier string.
+        Defaults to the context's ContextIdentifier.
+    :param representation_type: The RepresentationType string ("Face",
+        "Edge", "Vertex"). Inferred from item class if not given.
+    :return: The newly created IfcTopologyRepresentation entity.
+
+    Example:
+
+    .. code:: python
+
+        context = ifcopenshell.util.representation.get_context(
+            model, "Model", "Reference", "GRAPH_VIEW")
+        face = model.createIfcFaceSurface(bounds, surface, True)
+        rep = ifcopenshell.api.geometry.add_topology_representation(
+            model, context=context, item=face)
+        ifcopenshell.api.geometry.assign_representation(
+            model, product=member, representation=rep)
+    """
+    if representation_identifier is None:
+        representation_identifier = context.ContextIdentifier
+
+    if representation_type is None:
+        for ifc_class, rep_type in _ITEM_TYPE_TO_REP_TYPE.items():
+            if item.is_a(ifc_class):
+                representation_type = rep_type
+                break
+        else:
+            representation_type = "Undefined"
+
+    return file.createIfcTopologyRepresentation(
+        context,
+        representation_identifier,
+        representation_type,
+        [item],
+    )

src/ifcopenshell-python/ifcopenshell/api/structural/__init__.py

@@ -30,7 +30,9 @@ from .add_structural_load import add_structural_load
 from .add_structural_load_case import add_structural_load_case
 from .add_structural_load_group import add_structural_load_group
 from .add_structural_member_connection import add_structural_member_connection
+from .assign_product import assign_product
 from .assign_structural_analysis_model import assign_structural_analysis_model
+from .assign_to_building import assign_to_building
 from .edit_structural_analysis_model import edit_structural_analysis_model
 from .edit_structural_boundary_condition import edit_structural_boundary_condition
 from .edit_structural_connection_cs import edit_structural_connection_cs
@@ -57,7 +59,9 @@ __all__ = [
     "add_structural_load_case",
     "add_structural_load_group",
     "add_structural_member_connection",
+    "assign_product",
     "assign_structural_analysis_model",
+    "assign_to_building",
     "edit_structural_analysis_model",
     "edit_structural_boundary_condition",
     "edit_structural_connection_cs",

src/ifcopenshell-python/ifcopenshell/api/structural/assign_product.py

@@ -0,0 +1,64 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2026 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+# This file was generated with the assistance of an AI coding tool.
+
+import ifcopenshell
+import ifcopenshell.api.root
+
+
+def assign_product(
+    file: ifcopenshell.file,
+    relating_product: ifcopenshell.entity_instance,
+    related_object: ifcopenshell.entity_instance,
+) -> ifcopenshell.entity_instance:
+    """Links an object to a product via IfcRelAssignsToProduct
+
+    Typically used to associate a physical building element with a structural
+    analysis member (IfcStructuralSurfaceMember, IfcStructuralCurveMember) so
+    that analysis results can be traced back to the physical model.
+
+    :param relating_product: The IfcProduct that the object is assigned to,
+        typically an IfcStructuralMember.
+    :param related_object: The IfcObjectDefinition being assigned, typically
+        a physical building element such as an IfcWall or IfcSlab.
+    :return: The IfcRelAssignsToProduct relationship.
+
+    Example:
+
+    .. code:: python
+
+        wall = ifcopenshell.api.root.create_entity(model, ifc_class="IfcWall")
+        member = ifcopenshell.api.root.create_entity(
+            model, ifc_class="IfcStructuralSurfaceMember")
+        ifcopenshell.api.structural.assign_product(model,
+            relating_product=member, related_object=wall)
+    """
+    for rel in relating_product.ReferencedBy or []:
+        if not rel.is_a("IfcRelAssignsToProduct"):
+            continue
+        if related_object in rel.RelatedObjects:
+            return rel
+        related_objects = list(rel.RelatedObjects)
+        related_objects.append(related_object)
+        rel.RelatedObjects = related_objects
+        return rel
+
+    rel = ifcopenshell.api.root.create_entity(file, ifc_class="IfcRelAssignsToProduct")
+    rel.RelatingProduct = relating_product
+    rel.RelatedObjects = [related_object]
+    return rel

src/ifcopenshell-python/ifcopenshell/api/structural/assign_to_building.py

@@ -0,0 +1,64 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2026 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+# This file was generated with the assistance of an AI coding tool.
+
+import ifcopenshell
+import ifcopenshell.api.owner
+import ifcopenshell.guid
+
+
+def assign_to_building(
+    file: ifcopenshell.file,
+    structural_analysis_model: ifcopenshell.entity_instance,
+    building: ifcopenshell.entity_instance,
+) -> ifcopenshell.entity_instance:
+    """Associates a structural analysis model with a building via IfcRelServicesBuildings
+
+    The existing :func:`assign_structural_analysis_model` handles
+    IfcRelAssignsToGroup (linking structural members to the analysis model).
+    This function handles the separate model-to-building relationship, which
+    records which building the structural analysis model serves.
+
+    :param structural_analysis_model: The IfcStructuralAnalysisModel to
+        associate with the building.
+    :param building: The IfcBuilding (or other IfcSpatialStructureElement)
+        that the structural analysis model serves.
+    :return: The IfcRelServicesBuildings relationship.
+
+    Example:
+
+    .. code:: python
+
+        building = ifcopenshell.util.selector.filter_elements(model, "IfcBuilding")[0]
+        model_ = ifcopenshell.api.structural.add_structural_analysis_model(model)
+        ifcopenshell.api.structural.assign_to_building(model,
+            structural_analysis_model=model_, building=building)
+    """
+    for rel in structural_analysis_model.ServicesBuildings or []:
+        if building in rel.RelatedBuildings:
+            return rel
+        rel.RelatedBuildings = list(rel.RelatedBuildings) + [building]
+        return rel
+
+    return file.create_entity(
+        "IfcRelServicesBuildings",
+        ifcopenshell.guid.new(),
+        OwnerHistory=ifcopenshell.api.owner.create_owner_history(file),
+        RelatingSystem=structural_analysis_model,
+        RelatedBuildings=[building],
+    )

src/ifcopenshell-python/test/api/geometry/test_add_topology_representation.py

@@ -0,0 +1,82 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2026 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+# This file was generated with the assistance of an AI coding tool.
+
+import ifcopenshell.api.context
+import ifcopenshell.api.geometry
+import ifcopenshell.api.root
+import test.bootstrap
+
+
+class TestAddTopologyRepresentation(test.bootstrap.IFC4):
+    def setup_context(self):
+        ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcProject")
+        model = ifcopenshell.api.context.add_context(self.file, context_type="Model")
+        return ifcopenshell.api.context.add_context(
+            self.file,
+            context_type="Model",
+            context_identifier="Reference",
+            target_view="GRAPH_VIEW",
+            parent=model,
+        )
+
+    def test_creates_topology_representation(self):
+        context = self.setup_context()
+        face = self.file.create_entity("IfcFaceSurface")
+        rep = ifcopenshell.api.geometry.add_topology_representation(self.file, context=context, item=face)
+        assert rep.is_a("IfcTopologyRepresentation")
+        assert rep.ContextOfItems == context
+        assert face in rep.Items
+
+    def test_infers_face_representation_type(self):
+        context = self.setup_context()
+        face = self.file.create_entity("IfcFaceSurface")
+        rep = ifcopenshell.api.geometry.add_topology_representation(self.file, context=context, item=face)
+        assert rep.RepresentationType == "Face"
+
+    def test_infers_edge_representation_type(self):
+        context = self.setup_context()
+        edge = self.file.create_entity("IfcEdge")
+        rep = ifcopenshell.api.geometry.add_topology_representation(self.file, context=context, item=edge)
+        assert rep.RepresentationType == "Edge"
+
+    def test_defaults_representation_identifier_to_context_identifier(self):
+        context = self.setup_context()
+        face = self.file.create_entity("IfcFaceSurface")
+        rep = ifcopenshell.api.geometry.add_topology_representation(self.file, context=context, item=face)
+        assert rep.RepresentationIdentifier == context.ContextIdentifier
+
+    def test_custom_representation_identifier(self):
+        context = self.setup_context()
+        face = self.file.create_entity("IfcFaceSurface")
+        rep = ifcopenshell.api.geometry.add_topology_representation(
+            self.file, context=context, item=face, representation_identifier="Body"
+        )
+        assert rep.RepresentationIdentifier == "Body"
+
+    def test_custom_representation_type_overrides_inferred(self):
+        context = self.setup_context()
+        face = self.file.create_entity("IfcFaceSurface")
+        rep = ifcopenshell.api.geometry.add_topology_representation(
+            self.file, context=context, item=face, representation_type="Undefined"
+        )
+        assert rep.RepresentationType == "Undefined"
+
+
+class TestAddTopologyRepresentationIFC2X3(test.bootstrap.IFC2X3, TestAddTopologyRepresentation):
+    pass

src/ifcopenshell-python/test/api/structural/test_assign_product.py

@@ -0,0 +1,56 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2026 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+# This file was generated with the assistance of an AI coding tool.
+
+import ifcopenshell.api.root
+import ifcopenshell.api.structural
+import test.bootstrap
+
+
+class TestAssignProduct(test.bootstrap.IFC4):
+    def test_creating_a_new_relationship(self):
+        member = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcStructuralSurfaceMember")
+        wall = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        rel = ifcopenshell.api.structural.assign_product(self.file, relating_product=member, related_object=wall)
+        assert rel.is_a("IfcRelAssignsToProduct")
+        assert rel.RelatingProduct == member
+        assert wall in rel.RelatedObjects
+
+    def test_adding_a_second_object_to_an_existing_relationship(self):
+        member = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcStructuralSurfaceMember")
+        wall1 = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        wall2 = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        rel1 = ifcopenshell.api.structural.assign_product(self.file, relating_product=member, related_object=wall1)
+        rel2 = ifcopenshell.api.structural.assign_product(self.file, relating_product=member, related_object=wall2)
+        assert rel1 == rel2
+        assert len(self.file.by_type("IfcRelAssignsToProduct")) == 1
+        assert wall1 in rel1.RelatedObjects
+        assert wall2 in rel1.RelatedObjects
+
+    def test_does_not_duplicate_an_existing_assignment(self):
+        member = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcStructuralSurfaceMember")
+        wall = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        ifcopenshell.api.structural.assign_product(self.file, relating_product=member, related_object=wall)
+        ifcopenshell.api.structural.assign_product(self.file, relating_product=member, related_object=wall)
+        assert len(self.file.by_type("IfcRelAssignsToProduct")) == 1
+        rels = self.file.by_type("IfcRelAssignsToProduct")
+        assert len(rels[0].RelatedObjects) == 1
+
+
+class TestAssignProductIFC2X3(test.bootstrap.IFC2X3, TestAssignProduct):
+    pass

src/ifcopenshell-python/test/api/structural/test_assign_to_building.py

@@ -0,0 +1,62 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2026 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+# This file was generated with the assistance of an AI coding tool.
+
+import ifcopenshell.api.root
+import ifcopenshell.api.structural
+import test.bootstrap
+
+
+class TestAssignToBuilding(test.bootstrap.IFC4):
+    def test_creating_a_new_relationship(self):
+        model = ifcopenshell.api.structural.add_structural_analysis_model(self.file)
+        building = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcBuilding")
+        rel = ifcopenshell.api.structural.assign_to_building(
+            self.file, structural_analysis_model=model, building=building
+        )
+        assert rel.is_a("IfcRelServicesBuildings")
+        assert rel.RelatingSystem == model
+        assert building in rel.RelatedBuildings
+
+    def test_adding_a_second_building_to_an_existing_relationship(self):
+        model = ifcopenshell.api.structural.add_structural_analysis_model(self.file)
+        building1 = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcBuilding")
+        building2 = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcBuilding")
+        rel1 = ifcopenshell.api.structural.assign_to_building(
+            self.file, structural_analysis_model=model, building=building1
+        )
+        rel2 = ifcopenshell.api.structural.assign_to_building(
+            self.file, structural_analysis_model=model, building=building2
+        )
+        assert rel1 == rel2
+        assert len(self.file.by_type("IfcRelServicesBuildings")) == 1
+        assert building1 in rel1.RelatedBuildings
+        assert building2 in rel1.RelatedBuildings
+
+    def test_does_not_duplicate_an_existing_assignment(self):
+        model = ifcopenshell.api.structural.add_structural_analysis_model(self.file)
+        building = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcBuilding")
+        ifcopenshell.api.structural.assign_to_building(self.file, structural_analysis_model=model, building=building)
+        ifcopenshell.api.structural.assign_to_building(self.file, structural_analysis_model=model, building=building)
+        assert len(self.file.by_type("IfcRelServicesBuildings")) == 1
+        rels = self.file.by_type("IfcRelServicesBuildings")
+        assert len(rels[0].RelatedBuildings) == 1
+
+
+class TestAssignToBuildingIFC2X3(test.bootstrap.IFC2X3, TestAssignToBuilding):
+    pass