161 lines
6.7 KiB
Python
161 lines
6.7 KiB
Python
# IfcOpenShell - IFC toolkit and geometry engine
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# Copyright (C) 2021 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.geometry
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import ifcopenshell.api.owner
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import ifcopenshell.api.spatial
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import ifcopenshell.guid
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import ifcopenshell.util.element
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import ifcopenshell.util.placement
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def assign_object(
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file: ifcopenshell.file,
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products: list[ifcopenshell.entity_instance],
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relating_object: ifcopenshell.entity_instance,
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) -> Union[ifcopenshell.entity_instance, None]:
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"""Assigns object as an aggregate to the products
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All physical IFC model elements must be part of a hierarchical tree
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called the "spatial decomposition", where large things are made up of
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smaller things. This tree always begins at an "IfcProject" and is then
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broken down using "decomposition" relationships, of which aggregation is
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the first relationship you will use.
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Typically used when you want to describe how large spaces are made up of
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smaller spaces. For example large spatial elements (e.g. sites,
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buidings) can be made out of smaller spatial elements (e.g. storeys,
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spaces).
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The largest space (typically the IfcSite) can then be aggregated in a
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project. It is requirement for all spatial structures to be directly or
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indirectly aggregated back to the IfcProject to create a hierarchy of
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spaces.
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The other common usecase is when larger physical products are made up of
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smaller physical products. For example, a stair might be made out of a
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flight, a landing, a railing and so on. Or a wall might be made out of
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stud members, and coverings.
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As a product may only have a single location in the "spatial
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decomposition" tree, assigning an aggregate relationship will remove any
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previous aggregation, containment, or nesting relationships it may have.
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IFC placements follow a convention where the placement is relative to
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its parent in the spatial hierarchy. If your product has a placement,
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its placement will be recalculated to follow this convention.
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:param products: The list of parts of the aggregate, typically of IfcElement or
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IfcSpatialStructureElement subclass
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:param relating_object: The whole of the aggregate, typically an
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IfcElement or IfcSpatialStructureElement subclass
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:return: The IfcRelAggregate relationship instance
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or `None` if `products` was 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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element = ifcopenshell.api.root.create_entity(model, ifc_class="IfcSite")
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subelement = ifcopenshell.api.root.create_entity(model, ifc_class="IfcBuilding")
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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=[element], relating_object=project)
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# The site has a building
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ifcopenshell.api.aggregate.assign_object(model, products=[subelement], relating_object=element)
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"""
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if not products:
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return
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products_set = set(products)
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is_decomposed_by = next((i for i in relating_object.IsDecomposedBy if i.is_a("IfcRelAggregates")), None)
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previous_aggregates_rels: set[ifcopenshell.entity_instance] = set()
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products_without_aggregates: list[ifcopenshell.entity_instance] = []
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products_with_aggregates: list[ifcopenshell.entity_instance] = []
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# check if there is anything to change
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for product in products_set:
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product_rel = next(iter(product.Decomposes), None)
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if product_rel is None:
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products_without_aggregates.append(product)
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continue
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# either is_decomposed_by is None or product is part of different rel
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if product_rel != is_decomposed_by:
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previous_aggregates_rels.add(product_rel)
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products_with_aggregates.append(product)
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# products with already assigned aggregates will be skipped
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products_to_change = products_without_aggregates + products_with_aggregates
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# nothing to change
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if not products_to_change:
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return is_decomposed_by
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# can be either only aggregated or only contained at the same time
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# some product might not be able to have a container
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possibly_contained_products = [p for p in products_without_aggregates if hasattr(p, "ContainedInStructure")]
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ifcopenshell.api.spatial.unassign_container(file, products=possibly_contained_products)
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# unassign elements from previous aggregates
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for decomposes in previous_aggregates_rels:
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related_objects = set(decomposes.RelatedObjects) - products_set
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if related_objects:
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decomposes.RelatedObjects = list(related_objects)
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ifcopenshell.api.owner.update_owner_history(file, element=decomposes)
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else:
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history = decomposes.OwnerHistory
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file.remove(decomposes)
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if history:
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ifcopenshell.util.element.remove_deep2(file, history)
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# assign elements to a new aggregate
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if is_decomposed_by:
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is_decomposed_by.RelatedObjects = list(set(is_decomposed_by.RelatedObjects) | products_set)
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ifcopenshell.api.owner.update_owner_history(file, element=is_decomposed_by)
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else:
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is_decomposed_by = file.create_entity(
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"IfcRelAggregates",
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**{
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"GlobalId": ifcopenshell.guid.new(),
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"OwnerHistory": ifcopenshell.api.owner.create_owner_history(file),
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"RelatedObjects": list(products_set),
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"RelatingObject": relating_object,
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}
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)
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# localize placement relative to a new aggregate for affected products
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for product in products_to_change:
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placement = getattr(product, "ObjectPlacement", None)
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if placement and placement.is_a("IfcLocalPlacement"):
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ifcopenshell.api.geometry.edit_object_placement(
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file,
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product=product,
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matrix=ifcopenshell.util.placement.get_local_placement(product.ObjectPlacement),
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is_si=False,
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)
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return is_decomposed_by
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