182 lines
8.0 KiB
Python
182 lines
8.0 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.aggregate
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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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def assign_object(
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file: ifcopenshell.file,
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related_objects: 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 objects as nested children to a parent host
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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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Another type of "decomposition" relationship is known as "nesting".
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Nesting is used when an child object is physically attached to a parent
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host object, through a physical predetermined connection point. The
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child object must be specifically designed to attach to a other objects
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at specific positions with a particular form factor. Examples include
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faucets which must always be attached through a predrilled hole in a
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basin. Alternatively, it could be a modular attachment with a
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correlating male and female joint that must join at a particular point.
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Because there is a strict connection point, when the parent moves, all
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nested children must move with the parent. Another example might be a
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predrilled hole in a door panel where hardware must fit through.
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Nesting relationships are not very commonly used in most design and
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construction models. Its main usecase is in modular construction, kit of
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parts, or fabrication models.
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As a product may only have a single location in the "spatial
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decomposition" tree, assigning an nesting 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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For physical connections which are part of a distribution system, such
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as a plug connecting into a GPO, or a duct connecting to an AHU, or two
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pipe segments connecting with a bend, tee, or wye fitting, you should
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not nest the two objects directly. Instead, you should nest a connection
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port, which determines the type of compatible distribution flow that can
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be connected to it. To do this, do not use this function, but instead
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use the more specific functions in the ifcopenshell.api.system module.
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Note that nesting relationships may also be used by non-physical
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elements, such as cost items or tasks. In this context, nesting means
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that there is an implied order to the child cost items or tasks (i.e.
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task 1 should be shown before task 2). It is not necessary to use this
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function for nesting non-physical elements. Instead, it is recommended
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to instead just use the relevant API functions, like
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ifcopenshell.api.cost.add_cost_item or
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ifcopenshell.api.sequence.add_task.
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:param related_objects: The list of children of the nesting relationship,
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typically IfcElements.
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:param relating_object: The host parent of the nesting relationship,
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typically an IfcElement.
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:return: The IfcRelNests relationship instance
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or `None` if `related_objects` was empty list.
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Example:
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.. code:: python
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# Faucets are designed to attach onto a sink through a predrilled hole.
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sink = ifcopenshell.api.root.create_entity(model,
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ifc_class="IfcSanitaryTerminal", predefined_type="SINK")
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faucet = ifcopenshell.api.root.create_entity(model,
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ifc_class="IfcValve", predefined_type="FAUCET")
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ifcopenshell.api.nest.assign_object(model, related_objects=[faucet], relating_object=sink)
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"""
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settings = {"related_objects": related_objects, "relating_object": relating_object}
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if not settings["related_objects"]:
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return
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ifc2x3 = file.schema == "IFC2X3"
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related_objects_set = set(related_objects)
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if ifc2x3:
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is_nested_by = next((i for i in relating_object.IsDecomposedBy if i.is_a("IfcRelNests")), None)
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else:
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is_nested_by = next((i for i in relating_object.IsNestedBy), None)
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# NOTE: maintain .RelatedObjects order as it has meaning in IFC
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previous_nests_rels: set[ifcopenshell.entity_instance] = set()
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objects_without_nests: list[ifcopenshell.entity_instance] = []
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objects_with_nests: list[ifcopenshell.entity_instance] = []
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# check if there is anything to change
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for object in related_objects_set:
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if ifc2x3:
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object_rel = next((i for i in object.Decomposes if i.is_a("IfcRelNests")), None)
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else:
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object_rel = next(iter(object.Nests), None)
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if object_rel is None:
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objects_without_nests.append(object)
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continue
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# either is_nested_by is None or product is part of different rel
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if object_rel != is_nested_by:
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previous_nests_rels.add(object_rel)
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objects_with_nests.append(object)
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# products with already assigned nestings will be skipped
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objects_to_change = objects_without_nests + objects_with_nests
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# nothing to change
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if not objects_to_change:
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return is_nested_by
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# Can be either only nested, aggregated, or contained at the same time.
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possibly_contained = [o for o in objects_without_nests if hasattr(o, "ContainedInStructure")]
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ifcopenshell.api.spatial.unassign_container(file, products=possibly_contained)
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ifcopenshell.api.aggregate.unassign_object(file, products=objects_without_nests)
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# unassign elements from previous nests
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for nests in previous_nests_rels:
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cur_related_objects = [o for o in nests.RelatedObjects if o not in related_objects_set]
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if cur_related_objects:
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nests.RelatedObjects = list(cur_related_objects)
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ifcopenshell.api.owner.update_owner_history(file, element=nests)
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else:
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history = nests.OwnerHistory
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file.remove(nests)
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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 nesting
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if is_nested_by:
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cur_related_objects = list(is_nested_by.RelatedObjects)
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cur_related_objects_set = set(cur_related_objects)
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is_nested_by.RelatedObjects = cur_related_objects + [
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o for o in related_objects if o not in cur_related_objects_set
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]
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ifcopenshell.api.owner.update_owner_history(file, element=is_nested_by)
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else:
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is_nested_by = file.create_entity(
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"IfcRelNests",
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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": related_objects,
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"RelatingObject": relating_object,
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}
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)
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# NOTE: Creating a nesting relationship doesn't localize the object's placement,
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# unlike assigning it to an aggregate or a container.
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return is_nested_by
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