ifcpatch.recipes.AssignConstituentFractions

Module Contents

class ifcpatch.recipes.AssignConstituentFractions.Patcher(file: ifcopenshell.file, logger: logging.Logger, *args)

Assigns fractions to material constituents based on their “width”.

In Reference View MVD, material layer information is exchanged through IfcMaterialConstituentSet and IfcPhysicalComplexQuantity instead of IfcMaterialLayerSet. The layer thicknesses are stored as IfcQuantityLength within IfcPhysicalComplexQuantity with a Discrimination of ‘layer’.

While the Fraction attribute in IfcMaterialConstituent is optional, it’s valuable for downstream applications as it indicates the relative proportion of each constituent in the total material composition in a more straightforward way. However, authoring applications often export material constituents without setting this attribute.

This patcher helps maintain proper material information in Reference View exports by: 1. Finding width quantities from IfcPhysicalComplexQuantity with ‘layer’ discrimination 2. Using these widths to calculate relative proportions 3. Setting the optional but valuable Fraction attribute

For example, if a wall has constituents with widths of 0.1m and 0.2m, their fractions would be set to 0.333 and 0.667 respectively.

References: - IFC4 Reference View MVD: https://standards.buildingsmart.org/MVD/RELEASE/IFC4/ADD2_TC1/RV1_2/HTML/ - IfcMaterialConstituent: https://standards.buildingsmart.org/IFC/RELEASE/IFC4/ADD2_TC1/HTML/schema/ifcmaterialresource/lexical/ifcmaterialconstituent.htm

calculate_constituent_widths(constituents: List[ifcopenshell.entity_instance], elements: set[ifcopenshell.entity_instance], unit_scale: float) → Tuple[Dict[ifcopenshell.entity_instance, float], float]

Calculate the widths of constituents based on associated quantities.

get_element_quantities(element: ifcopenshell.entity_instance) → Dict[str, float]

Get width quantities for an element.

patch()

Execute the patch to assign fractions to material constituents.

file

logger