Ryan Schultz 036ee098a6 Fix slab layer geometry: custom offset isolation, unit scale, and layer ordering
Three related bugs fixed in the slab material layer set workflow:

1. EditAssignedMaterial (operator.py): Applying a custom offset to one slab
   instance incorrectly regenerated geometry for ALL slabs sharing the same
   IfcMaterialLayerSet. Replaced regenerate_from_layer_set (sweeps all users)
   with per-element regenerate_from_occurence for AXIS3 slabs and targeted
   recalculate_walls for AXIS2 walls. Each element's IfcMaterialLayerSetUsage
   attributes are now updated individually before regeneration.

2. slice_layerset_mesh (loader.py): Loader.unit_scale is a class variable only
   set during full file import, so it was stale (= 1) during live geometry
   updates on foot-based IFC files. Layer bisect planes were being computed in
   IFC feet while the mesh was in Blender metres, placing all cuts completely
   outside the mesh. Fixed by computing unit_scale fresh from the IFC file on
   each call via ifcopenshell.util.unit.calculate_unit_scale.

3. OffsetFromReferenceLine stale / layer order reversed (slab.py, loader.py):
   A guard (and custom_offset is None) in change_thickness prevented writing
   the correct OffsetFromReferenceLine (position.z) to the usage when a custom
   offset was active. This left the value at 0.0 instead of the actual slab
   bottom (e.g. -1.0 IFC units for a TOP-reference slab), so the bisect
   starting point co was at the reference plane rather than the slab bottom,
   reversing layer assignments or missing layers entirely. Removed the guard —
   safe because each element has its own IfcMaterialLayerSetUsage instance.
   Reverted the AXIS3 bisect normal back to (0,0,1) (upward from co at slab
   bottom) which is correct once OffsetFromReferenceLine is properly set.
2026-03-14 12:21:35 -05:00
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IfcOpenShell

IfcOpenShell is an open source (LGPL) software library for working with Industry Foundation Classes (IFC). Complete parsing support is provided for IFC2x3 TC1, IFC4 Add2 TC1, IFC4x1, IFC4x2, and IFC4x3 Add2. Extensive geometric support is implemented for the IFC releases IFC2x3 TC1 and IFC4 Add2 TC1. Extending with support for arbitrary IFC schemas is possible at compile-time when using C++ and at run-time when using Python.

In addition to a C++ and Python API, IfcOpenShell comes with an ecosystem of tools, notably including IfcConvert (an application to convert IFC models to other formats), Bonsai (an add-on to Blender providing a graphical IFC authoring platform), and many other libraries, CLI apps, and more. Support is also provided for auxiliary standards such as BCF and IDS.

For more information, see:

Development is sponsored through your generous donations!

Open Collective Contributors

Contents

Name Description License Service
bcf Library to read and write BCF-XML and query OpenCDE BCF-API modules LGPL-3.0-or-later PyPI Anaconda-Server Badge
bonsai Add-on to Blender providing a graphical native IFC authoring platform GPL-3.0-or-later Official GitHub Unstable Chocolatey
bsdd Library to query the bSDD API LGPL-3.0-or-later PyPI
ifc2ca Utility to convert IFC structural analysis models to Code_Aster LGPL-3.0-or-later
ifc4d Convert to and from IFC and project management software LGPL-3.0-or-later PyPI
ifc5d Report and optimise cost information from IFC LGPL-3.0-or-later PyPI
ifcbimtester Wrapper for Gherkin based unit testing for IFC models LGPL-3.0-or-later
ifcblender Historic Blender IFC import add-on LGPL-3.0-or-later*
ifccityjson Convert CityJSON to IFC LGPL-3.0-or-later PyPI
ifcclash Clash detection library and CLI app LGPL-3.0-or-later PyPI
ifcconvert CLI app to convert IFC to many other formats LGPL-3.0-or-later* Official GitHub
ifccsv Library and CLI app to export and import schedules from IFC LGPL-3.0-or-later PyPI
ifcdiff Compare changes between IFC models LGPL-3.0-or-later PyPI
ifcfm Extract IFC data for FM handover requirements LGPL-3.0-or-later PyPI
ifcmax Historic extension for IFC support in 3DS Max LGPL-3.0-or-later* Official
ifcopenshell-python Python library for IFC manipulation LGPL-3.0-or-later* Official GitHub PyPI Anaconda Anaconda Docker AUR AUR Unstable Pyodide WASM Wheels
ifcpatch Utility to run pre-packaged scripts to manipulate IFCs LGPL-3.0-or-later PyPI
ifcsverchok Blender Add-on for visual node programming with IFC GPL-3.0-or-later GitHub Unstable
ifctester Library, CLI and webapp for IDS model auditing LGPL-3.0-or-later PyPI

The IfcOpenShell C++ codebase is split into multiple interal libraries:

Name Description License
ifcgeom Internal library for IfcOpenShell LGPL-3.0-or-later*
ifcgeom_schema_agnostic Internal library for IfcOpenShell LGPL-3.0-or-later*
ifcgeomserver Internal library for IfcOpenShell LGPL-3.0-or-later*
ifcjni Internal library for IfcOpenShell LGPL-3.0-or-later*
ifcparse Internal library for IfcOpenShell LGPL-3.0-or-later*
ifcwrap Internal library for IfcOpenShell LGPL-3.0-or-later*
qtviewer Internal library for IfcOpenShell LGPL-3.0-or-later*
serializers Internal library for IfcOpenShell LGPL-3.0-or-later*
S
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