Merging more than two IFC models with the MergeProjects recipe leaves
duplicated IfcGeometricRepresentationContext entities behind. All elements
are kept, but the accumulated contexts cause later disciplines to appear
"not merged" in viewers.
This test merges three projects and asserts the elements are kept, a single
IfcProject remains, and the geometric contexts are reused rather than
accumulated. It currently fails on the context assertion, reproducing #7973.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The Migrate recipe previously crashed mid-loop with the cryptic
`RuntimeError: Entity with name '' not found in schema 'IFC2X3'` when
asked to downgrade an IFC4 or IFC4X3 file to IFC2X3 — the
class_4_to_2x3 mapping marks IFC4-only geometry / element classes with
an empty-string sentinel and the old code blindly forwarded that to
create_entity. Real files routinely contain IfcPolygonalFaceSet,
IfcTriangulatedFaceSet, IfcIndexedPolyCurve, IfcLamp, IfcPipeSegment,
IfcGeographicElement, etc.
The recipe now runs a preprocessing pipeline when the target is IFC2X3
and the source is IFC4 or IFC4X3:
- DowngradeIndexedPolyCurve flattens IfcIndexedPolyCurve to IfcPolyline
for the whole file (arcs included — see below).
- IfcPolygonalFaceSet / IfcTriangulatedFaceSet are converted directly
to IfcFacetedBrep at the entity level via
ifcopenshell.util.shape_builder.polygonal_face_set_to_faceted_brep,
preserving topology including IfcIndexedPolygonalFaceWithVoids inner
bounds. IfcShapeRepresentation carriers have their RepresentationType
tag updated from "Tessellation" to "Brep".
- Orphan source-only geometry instances (left over after the rewires)
are purged iteratively via
geometry_classes_introduced_after(target, source).
The Migrator is invoked with fallback_element_to_proxy=True so
IFC4-only IfcElement subclasses (IfcLamp, IfcPipeSegment,
IfcGeographicElement, ...) become IfcBuildingElementProxy in the
output. A post-pass encodes "<OriginalClass>/<PredefinedType>" into
ObjectType (e.g. "IfcLamp/COMPACTFLUORESCENT") when ObjectType is
empty, so the lost subclass identity survives the downgrade as
searchable text.
The migration loop now collects per-entity failures into a list rather
than crashing on the first; a summary RuntimeError fires at end if any
failed, naming up to 20 with their inverse references. Successful
migrations log a single count line via self.logger.
DowngradeIndexedPolyCurve extended:
- Arc segments (IfcArcIndex) are flattened via
ifcopenshell.util.shape_builder.arc_to_polyline_points with
ARC_SUBDIVISION=16 chord points per arc.
- Multi-index IfcLineIndex segments handled correctly.
- Absent Segments list (IFC4 polyline-through-all-coords case) handled.
Test coverage: 11 tests across the two recipes covering all four
preprocessing branches, the IFC4X3 source gate, the ObjectType
encoding (incl. author-supplied ObjectType preservation), the summary
RuntimeError shape, and the arc subdivision.
Generated with the assistance of an AI coding tool.
* fix: Rename the "MergeProject" recipe to "MergeProjects"
This rename, alongside renaming "filepath" to "filepaths" and adjusting the docstring has been done to clarify, that this patch can be used to merge multiple IFC files into one (and not just two)
* fix: Fix `test_Merge_Project.py`, which was broken due to renaming the patch recipe
In IFC it's possible for a property set to be assigned to multiple elements and which may lead to confusing behaviour when you edit a pset on one element and other element seems to get edited too.
Which makes it worse is that that it is possible that some software is might be doing this unintentionally when exporting IFC (as some sort of optimization as storing 1 is more optimal than n copies of it).
So now there are some tools in Bonsai and in IfcOpenShell to handle the shared psest:
1) Indication that property is shared - https://imgur.com/a/9dd3jST (similar to how Blender indicates ID data-block users). You can click on it to "unshare" the pset - a new copy for the pset will be created and it's going to be linked only to the active object.
2) api pset.unshare_pset method that does the same. And util.element.get_elements_using_pset method that encapsulates schema differences and different approaches for occurrences/types.
3) ifcpatch recipe 'UnsharePsets' that's making all property sets in the IFC file to have just 1 element that's using them. You can limit the affected elements by providing query.
ifcpatch recipe is also available in Bonsai - https://i.imgur.com/aOCx7HI.png
ifcpatch ConvertLengthUnit - change used units from plural to singular names, to make it consistent across the api
more test coverage - test converting to more units and back from them
Thomas Krijnen
