# IfcOpenShell - IFC toolkit and geometry engine # Copyright (C) 2021 Dion Moult # # 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 . import ifcopenshell import ifcopenshell.util.unit class Usecase: def __init__(self, file, units=None, length=None, area=None, volume=None): """Assign default project units Whenever a unitised quantity is specified, such as a length, area, voltage, pressure, etc, these project units are used by default. It is also possible to override units for specific properties. For example, generally you might want square metres for area measurements, but you might want square millimeters for the measurements of the cross sectional area of cables in cable trays. However, this function only deals with the default project units. :param units: A list of units to assign as project defaults. See ifcopenshell.api.unit.add_si_unit, unit.add_conversion_based_unit, and unit.add_monetary_unit for information on how to create units. :type units: list[ifcopenshell.entity_instance.entity_instance],optional :return: The IfcUnitAssignment element :rtype: ifcopenshell.entity_instance.entity_instance Example: .. code:: python # You need a project before you can assign units. ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcProject") # Millimeters and square meters length = ifcopenshell.api.run("unit.add_si_unit", model, unit_type="LENGTHUNIT", prefix="MILLI") area = ifcopenshell.api.run("unit.add_si_unit", model, unit_type="AREAUNIT") # Make it our default units, if we are doing a metric building ifcopenshell.api.run("unit.assign_unit", model, units=[length, area]) # Alternatively, you may specify without any arguments to # automatically create millimeters, square meters, and cubic meters # as a convenience for testing purposes. Sorry imperial folks, we # prioritise metric here. ifcopenshell.api.run("unit.assign_unit", model) """ self.file = file self.settings = {"units": units} # This is a convenience function, likely to be deprecated in the future. self.settings["length"] = length or {"is_metric": True, "raw": "MILLIMETERS"} self.settings["area"] = area or {"is_metric": True, "raw": "METERS"} self.settings["volume"] = volume or {"is_metric": True, "raw": "METERS"} def execute(self): # We're going to refactor this to split unit creation and assignment if self.settings["units"]: units = self.settings["units"] else: del self.settings["units"] # TODO refactor units = [] for unit_type, data in self.settings.items(): if data["is_metric"]: units.append(self.create_metric_unit(unit_type, data)) else: units.append(self.create_imperial_unit(unit_type, data)) unit_assignment = self.get_unit_assignment() self.assign_units(unit_assignment, units) return unit_assignment def get_unit_assignment(self): unit_assignment = self.file.by_type("IfcUnitAssignment") if unit_assignment: unit_assignment = unit_assignment[0] # TODO: handle unit rewriting, which is complicated else: unit_assignment = self.file.createIfcUnitAssignment() if self.file.schema == "IFC2X3": self.file.by_type("IfcProject")[0].UnitsInContext = unit_assignment else: self.file.by_type("IfcContext")[0].UnitsInContext = unit_assignment return unit_assignment def assign_units(self, unit_assignment, new_units): units = set(unit_assignment.Units or []) for unit in new_units: units.add(unit) unit_assignment.Units = list(units) def create_metric_unit(self, unit_type, data): type_prefix = "" if unit_type == "area": type_prefix = "SQUARE_" elif unit_type == "volume": type_prefix = "CUBIC_" return self.file.createIfcSIUnit( None, "{}UNIT".format(unit_type.upper()), ifcopenshell.util.unit.get_prefix(data["raw"]), type_prefix + ifcopenshell.util.unit.get_unit_name(data["raw"]), ) def create_imperial_unit(self, unit_type, data): if unit_type == "length": dimensional_exponents = self.file.createIfcDimensionalExponents(1, 0, 0, 0, 0, 0, 0) name_prefix = "" elif unit_type == "area": dimensional_exponents = self.file.createIfcDimensionalExponents(2, 0, 0, 0, 0, 0, 0) name_prefix = "square" elif unit_type == "volume": dimensional_exponents = self.file.createIfcDimensionalExponents(3, 0, 0, 0, 0, 0, 0) name_prefix = "cubic" si_unit = self.file.createIfcSIUnit( None, "{}UNIT".format(unit_type.upper()), None, "{}METRE".format(name_prefix.upper() + "_" if name_prefix else ""), ) if data["raw"] == "INCHES": name = "{}inch".format(name_prefix + " " if name_prefix else "") elif data["raw"] == "FEET": name = "{}foot".format(name_prefix + " " if name_prefix else "") elif data["raw"] == "MILES": name = "{}mile".format(name_prefix + " " if name_prefix else "") elif data["raw"] == "THOU": name = "{}thou".format(name_prefix + " " if name_prefix else "") value_component = self.file.create_entity( "IfcReal", **{"wrappedValue": ifcopenshell.util.unit.si_conversions[name]} ) conversion_factor = self.file.createIfcMeasureWithUnit(value_component, si_unit) return self.file.createIfcConversionBasedUnit( dimensional_exponents, "{}UNIT".format(unit_type.upper()), name, conversion_factor )