120 lines
5.1 KiB
Python
120 lines
5.1 KiB
Python
# IfcOpenShell - IFC toolkit and geometry engine
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# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
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#
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# This file is part of IfcOpenShell.
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#
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# IfcOpenShell is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# IfcOpenShell is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public License
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# along with IfcOpenShell. If not, see <http://www.gnu.org/licenses/>.
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from typing import Union
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import ifcopenshell
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import ifcopenshell.api.owner
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import ifcopenshell.guid
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import ifcopenshell.util.element
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def reference_structure(
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file: ifcopenshell.file,
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products: list[ifcopenshell.entity_instance],
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relating_structure: ifcopenshell.entity_instance,
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) -> Union[ifcopenshell.entity_instance, None]:
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"""Denote that a list products is related to a list of spatial structures
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This is similar to ifcopenshell.api.spatial.assign_container, except
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that containment can only occur between a product and a single spatial
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structure element. This is fine if a wall is on level 1, but not
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appropriate if you have a multistorey column on multiple levels, or a
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door with a to and from space, or a stair going from one floor to
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another floor. This is where spatial referencing is used.
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Typically, the product will be contained in the lowermost, constructed
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first, or primarily accessible space. For a multistorey column or stair,
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the column or stair will therefore be contained in the lowermost storey.
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Then, any other storeys will be referenced.
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Referencing is non-hierarchical, so a door may be referenced in multiple
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spaces simultaneously.
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:param products: The list of physical IfcElements that exists in the space.
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:param relating_structure: The IfcSpatialStructureElement element, such
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as IfcBuilding, IfcBuildingStorey, or IfcSpace that the element
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exists in.
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:return: The IfcRelReferencedInSpatialStructure relationship instance
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or `None` if `products` was an empty list.
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Example:
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.. code:: python
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project = ifcopenshell.api.root.create_entity(model, ifc_class="IfcProject")
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site = ifcopenshell.api.root.create_entity(model, ifc_class="IfcSite")
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building = ifcopenshell.api.root.create_entity(model, ifc_class="IfcBuilding")
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storey1 = ifcopenshell.api.root.create_entity(model, ifc_class="IfcBuildingStorey")
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storey2 = ifcopenshell.api.root.create_entity(model, ifc_class="IfcBuildingStorey")
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storey3 = ifcopenshell.api.root.create_entity(model, ifc_class="IfcBuildingStorey")
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space = ifcopenshell.api.root.create_entity(model, ifc_class="IfcSpace")
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# The project contains a site (note that project aggregation is a special case in IFC)
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ifcopenshell.api.aggregate.assign_object(model, products=[site], relating_object=project)
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# The site has a building, the building has a storey, and the storey has a space
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ifcopenshell.api.aggregate.assign_object(model, products=[building], relating_object=site)
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ifcopenshell.api.aggregate.assign_object(model, products=[storey1,storey2,storey3], relating_object=building)
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ifcopenshell.api.aggregate.assign_object(model, products=[space], relating_object=storey1)
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# Create a column, this column spans 3 storeys
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column = ifcopenshell.api.root.create_entity(model, ifc_class="IfcWall")
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# The column is contained in the lowermost storey
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ifcopenshell.api.spatial.assign_container(model, products=[column], relating_structure=storey1)
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# And referenced in the others
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ifcopenshell.api.spatial.reference_structure(
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model, products=[column], relating_structure=storey2
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)
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ifcopenshell.api.spatial.reference_structure(
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model, products=[column], relating_structure=storey3
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)
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"""
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structure = relating_structure
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products_set = set(products)
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if not products_set:
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return
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referenced = ifcopenshell.util.element.get_structure_referenced_elements(structure)
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products_to_assign = products_set - referenced
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rel: Union[ifcopenshell.entity_instance, None]
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rel = next(iter(structure.ReferencesElements), None)
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if not products_to_assign:
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return rel
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if rel is None:
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rel = file.create_entity(
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"IfcRelReferencedInSpatialStructure",
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GlobalId=ifcopenshell.guid.new(),
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OwnerHistory=ifcopenshell.api.owner.create_owner_history(file),
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RelatedElements=list(products_to_assign),
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RelatingStructure=structure,
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)
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else:
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related_elements = set(rel.RelatedElements) | products_to_assign
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rel.RelatedElements = list(related_elements)
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ifcopenshell.api.owner.update_owner_history(file, element=rel)
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return rel
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