150 lines
6.5 KiB
Python
150 lines
6.5 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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import ifcopenshell
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import ifcopenshell.api.aggregate
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import ifcopenshell.api.geometry
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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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import ifcopenshell.util.placement
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def add_feature(
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file: ifcopenshell.file, feature: ifcopenshell.entity_instance, element: ifcopenshell.entity_instance
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) -> ifcopenshell.entity_instance:
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"""Create a projecting, voiding, or surface feature in an element
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There are three main types of features: those that add, remove, or
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influence geometry of a parent object.
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The most common of these is an opening. For example, it is often necessary
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to cut out openings in elements like walls and slabs to make space to
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insert doors, windows, and other services that go through these
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penetrations.
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Whereas it is possible to simply draw the wall as a rectangle with a
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hole in it for the opening, often these openings have specific meanings.
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For example, an opening might be filled with a window, and so when the
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window moves, the opening should move with it. Alternatively, the
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opening itself might have fire or acoustic requirements, such that any
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service or equipment passing through that space must also comply with
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those requirements. For these types of semantic openings, you should
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have a distinct opening element which voids your regular element. For
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example, your wall will still be a rectangular prism with no hole in it,
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and a separate opening element will have a box representing the extents
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of the opening for a window. The opening element will automatically
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perform a geometric boolean operation to cut out the wall's geometry.
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Whenever you have an opening in you project, you should determine
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whether or not the opening is semantic (i.e. should be represented by a
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distinct opening object) or non-semantic (i.e. should simply be
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booleaned or be part of the shape of the object).
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:param feature: The IfcFeatureElement to affect the element.
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:param element: The IfcElement to add the feature to.
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:return: The new IfcRelVoidsElement relationship
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Example:
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.. code:: python
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# A bit of preparation, let's create some geometric contexts since
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# we want to create some geometry for our wall and opening.
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model3d = ifcopenshell.api.context.add_context(model, context_type="Model")
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body = ifcopenshell.api.context.add_context(model,
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context_type="Model", context_identifier="Body", target_view="MODEL_VIEW", parent=model3d)
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# Create a wall
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wall = ifcopenshell.api.root.create_entity(model, ifc_class="IfcWall")
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# Let's use the "3D Body" representation we created earlier to add a
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# new wall-like body geometry, 5 meters long, 3 meters high, and
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# 200mm thick
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representation = ifcopenshell.api.geometry.add_wall_representation(model,
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context=body, length=5, height=3, thickness=0.2)
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ifcopenshell.api.geometry.assign_representation(model,
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product=wall, representation=representation)
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# Place our wall at the origin
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ifcopenshell.api.geometry.edit_object_placement(model, product=wall)
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# Create an opening, such as for a service penetration with fire and
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# acoustic requirements.
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opening = ifcopenshell.api.root.create_entity(model, ifc_class="IfcOpeningElement")
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# Let's create an opening representation of a 950mm x 2100mm door.
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# Notice how the thickness is greater than the wall thickness, this
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# helps resolve floating point resolution errors in 3D.
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representation = ifcopenshell.api.geometry.add_wall_representation(model,
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context=body, length=.95, height=2.1, thickness=0.4)
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ifcopenshell.api.geometry.assign_representation(model,
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product=opening, representation=representation)
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# Let's shift our door 1 meter along the wall and 100mm along the
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# wall, to create a nice overlap for the opening boolean.
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matrix = np.identity(4)
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matrix[:,3] = [1, -.1, 0, 0]
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ifcopenshell.api.geometry.edit_object_placement(model, product=opening, matrix=matrix)
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# The opening will now void the wall.
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ifcopenshell.api.feature.add_feature(model, feature=opening, element=wall)
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"""
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if feature.is_a("IfcFeatureElementSubtraction"):
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rels = feature.VoidsElements
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ifc_class = "IfcRelVoidsElement"
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elif feature.is_a("IfcFeatureElementAddition"):
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rels = feature.ProjectsElements
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ifc_class = "IfcRelProjectsElement"
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elif feature.is_a("IfcSurfaceFeature"):
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if file.schema == "IFC4":
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return ifcopenshell.api.aggregate.assign_object(file, [feature], element)
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rels = feature.AdheresToElement
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ifc_class = "IfcRelAdheresToElement"
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if rels:
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if rels[0][4] == element:
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return rels[0]
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elif ifc_class == "IfcRelAdheresToElement" and len(rels[0].RelatedSurfaceFeatures) != 1:
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rels[0].RelatedSurfaceFeatures = list(set(rels[0].RelatedSurfaceFeatures) - {feature})
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else:
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history = rels[0].OwnerHistory
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file.remove(rels[0])
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if history:
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ifcopenshell.util.element.remove_deep2(file, history)
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rel = file.create_entity(
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ifc_class,
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ifcopenshell.guid.new(),
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ifcopenshell.api.owner.create_owner_history(file),
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None,
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None,
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element,
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[feature] if ifc_class == "IfcRelAdheresToElement" else feature,
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)
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if (placement := feature.ObjectPlacement) 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=feature,
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matrix=ifcopenshell.util.placement.get_local_placement(placement),
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is_si=False,
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)
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return rel
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