Add geometry.copy_representation API

Deep-copies the named representation from a source element to a target
element.

Generated with the assistance of an AI coding tool.

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

@@ -52,6 +52,7 @@ from .disconnect_element import disconnect_element
 from .disconnect_path import disconnect_path
 from .edit_object_placement import edit_object_placement
 from .map_representation import map_representation
+from .copy_representation import copy_representation
 from .regenerate_wall_representation import regenerate_wall_representation
 from .remove_boolean import remove_boolean
 from .remove_representation import remove_representation
@@ -65,6 +66,7 @@ __all__ = [
     "add_boolean",
     "clip_solid",
     "clip_solid_bounded",
+    "copy_representation",
     "add_door_representation",
     "add_footprint_representation",
     "add_mesh_representation",

src/ifcopenshell-python/ifcopenshell/api/geometry/copy_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/>.
+
+from __future__ import annotations
+
+from typing import Optional
+
+import ifcopenshell.api.geometry
+import ifcopenshell.util.element
+import ifcopenshell.util.representation
+
+
+def copy_representation(
+    file: ifcopenshell.file,
+    source: ifcopenshell.entity_instance,
+    target: ifcopenshell.entity_instance,
+    context_identifier: str = "Body",
+) -> Optional[ifcopenshell.entity_instance]:
+    """Copy a geometric representation from one element to another.
+
+    Finds the named representation on ``source``, deep-copies its entity
+    graph (geometry items, profiles, placements, etc.), and assigns the copy
+    to ``target``.  Representation contexts are shared rather than copied.
+    If ``target`` already has a matching representation it is removed and
+    replaced.
+
+    If no matching representation is found on ``source``, returns ``None``
+    and leaves ``target`` unchanged.
+
+    :param source: The element to copy the representation from.
+    :param target: The element to assign the copied representation to.
+    :param context_identifier: The RepresentationIdentifier to look up on
+        ``source`` (e.g. ``"Body"``, ``"Axis"``, ``"Box"``).
+        Defaults to ``"Body"``.
+    :return: The newly created IfcShapeRepresentation, or None if no
+        matching representation was found on ``source``.
+
+    Example:
+
+    .. code:: python
+
+        wall_a = model.by_id(1)
+        wall_b = model.by_id(2)
+
+        # Give wall_b the same body geometry as wall_a.
+        ifcopenshell.api.geometry.copy_representation(model,
+            source=wall_a, target=wall_b)
+    """
+    source_rep = ifcopenshell.util.representation.get_representation(
+        source, "Model", context_identifier
+    )
+    if source_rep is None:
+        return None
+
+    new_rep = ifcopenshell.util.element.copy_deep(
+        file, source_rep, exclude=["IfcGeometricRepresentationContext"]
+    )
+
+    existing_rep = ifcopenshell.util.representation.get_representation(
+        target, "Model", context_identifier
+    )
+    if existing_rep:
+        ifcopenshell.api.geometry.unassign_representation(file, product=target, representation=existing_rep)
+        ifcopenshell.api.geometry.remove_representation(file, representation=existing_rep)
+
+    ifcopenshell.api.geometry.assign_representation(file, product=target, representation=new_rep)
+    return new_rep

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

@@ -0,0 +1,142 @@
+# 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/>.
+
+import ifcopenshell.api.geometry
+import ifcopenshell.api.root
+import ifcopenshell.util.representation
+import ifcopenshell.util.shape_builder
+import test.bootstrap
+
+
+class TestCopyRepresentation(test.bootstrap.IFC4):
+    def _body_context(self):
+        body = ifcopenshell.util.representation.get_context(self.file, "Model", "Body", "MODEL_VIEW")
+        if body is None:
+            model = self.file.createIfcGeometricRepresentationContext(
+                ContextType="Model", CoordinateSpaceDimension=3, Precision=1e-5,
+                WorldCoordinateSystem=self.file.createIfcAxis2Placement3D(
+                    self.file.createIfcCartesianPoint((0.0, 0.0, 0.0))
+                ),
+            )
+            body = self.file.createIfcGeometricRepresentationSubContext(
+                ContextIdentifier="Body", ContextType="Model",
+                TargetView="MODEL_VIEW", ParentContext=model,
+            )
+        return body
+
+    def _add_body_rep(self, element):
+        body = self._body_context()
+        rep = ifcopenshell.api.geometry.add_wall_representation(
+            self.file, context=body, length=5.0, height=3.0, thickness=0.2
+        )
+        ifcopenshell.api.geometry.assign_representation(self.file, product=element, representation=rep)
+        return rep
+
+    def test_copy_to_empty_target(self):
+        wall_a = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        wall_b = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        self._add_body_rep(wall_a)
+
+        result = ifcopenshell.api.geometry.copy_representation(
+            self.file, source=wall_a, target=wall_b
+        )
+
+        assert result is not None
+        assert result.is_a("IfcShapeRepresentation")
+        target_rep = ifcopenshell.util.representation.get_representation(wall_b, "Model", "Body")
+        assert target_rep is not None
+        assert target_rep == result
+
+    def test_source_rep_entities_are_distinct(self):
+        wall_a = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        wall_b = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        source_rep = self._add_body_rep(wall_a)
+
+        new_rep = ifcopenshell.api.geometry.copy_representation(
+            self.file, source=wall_a, target=wall_b
+        )
+
+        assert new_rep.id() != source_rep.id()
+        assert new_rep.Items[0].id() != source_rep.Items[0].id()
+
+    def test_context_is_shared_not_copied(self):
+        wall_a = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        wall_b = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        source_rep = self._add_body_rep(wall_a)
+
+        new_rep = ifcopenshell.api.geometry.copy_representation(
+            self.file, source=wall_a, target=wall_b
+        )
+
+        assert new_rep.ContextOfItems.id() == source_rep.ContextOfItems.id()
+
+    def test_replaces_existing_target_rep(self):
+        wall_a = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        wall_b = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        self._add_body_rep(wall_a)
+        old_rep = self._add_body_rep(wall_b)
+        old_rep_id = old_rep.id()
+
+        ifcopenshell.api.geometry.copy_representation(
+            self.file, source=wall_a, target=wall_b
+        )
+
+        try:
+            self.file.by_id(old_rep_id)
+            assert False, "old representation still exists"
+        except RuntimeError:
+            pass  # entity was removed, as expected
+
+    def test_source_unchanged_after_copy(self):
+        wall_a = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        wall_b = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        source_rep = self._add_body_rep(wall_a)
+        source_rep_id = source_rep.id()
+
+        ifcopenshell.api.geometry.copy_representation(
+            self.file, source=wall_a, target=wall_b
+        )
+
+        assert self.file.by_id(source_rep_id) is not None  # source must still exist
+        assert ifcopenshell.util.representation.get_representation(wall_a, "Model", "Body") is not None
+
+    def test_returns_none_when_no_matching_rep(self):
+        wall_a = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        wall_b = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+
+        result = ifcopenshell.api.geometry.copy_representation(
+            self.file, source=wall_a, target=wall_b
+        )
+
+        assert result is None
+
+    def test_custom_context_identifier(self):
+        wall_a = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        wall_b = ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcWall")
+        self._add_body_rep(wall_a)
+
+        # "Axis" doesn't exist on wall_a, so should return None
+        result = ifcopenshell.api.geometry.copy_representation(
+            self.file, source=wall_a, target=wall_b, context_identifier="Axis"
+        )
+
+        assert result is None
+
+
+class TestCopyRepresentationIFC2X3(test.bootstrap.IFC2X3, TestCopyRepresentation):
+    pass