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Petru Conduraru
1a81292eb4
Extends the PI method to horizontal alignments with clothoid spiral transition curves and cant profiles for railway engineering, with the geometry available as a pure, file-independent solver that any caller (interactive editors, scripts, importers) can reuse. solve_horizontal_alignment_by_pi_method() solves PI coordinates and radii into a continuous sequence of HorizontalSegmentDefinition values whose fields mirror IfcAlignmentHorizontalSegment. Each radii element is either a circular curve radius R or a (R, Lin, Lout) sequence giving the entry and exit spiral lengths. The circular curve is shifted inward so tangent runs, spirals, and the circular curve remain continuous in position and direction. Spiral end points are computed by Gauss-Legendre integration of the clothoid position functions (compute_clothoid_end, exposed for reuse), matching the exact clothoid to machine precision, and compute_horizontal_segment_end() lets callers verify continuity of any definition sequence without touching a file. layout_horizontal_alignment_by_pi_method() is now a thin writer over the solver: it accepts the same (R, Lin, Lout) elements and writes the solved definitions to an IfcAlignmentHorizontal layout. When a cant layout and cant values are given, cant segments are written one-for-one with the horizontal segments, as expected by the cant segment lookup used for Viennese bends: zero cant on tangent runs (CONSTANTCANT), linearly varying cant over spirals (LINEARTRANSITION), and constant cant over circular curves (CONSTANTCANT), applied to the rail on the outside of the curve. Curves with a non-zero cant require both spirals so the cant profile is continuous, which keeps the segmented reference curve schema-valid. The parity is structural: every solved definition carries its own cant values, so the two layouts cannot drift apart. create_by_pi_method() passes radii elements through and accepts optional cants and rail_head_distance; create() accepts rail_head_distance for IfcAlignmentCant.RailHeadDistance. Plain-R input routes through the verbatim legacy code path and produces unchanged output. The tests check the quadrature against an independent dense Simpson reference, pure-solver continuity (max position gap 1e-12), continuity of the written geometry on the C++ evaluator (max position gap 8.5e-7, the engine's clothoid series truncation), the cant profile and its segment parity, error conditions, and an end-to-end tangent-clothoid-arc-clothoid-tangent authoring example that validates cleanly against the schema and express rules. Part of #6890. Generated with the assistance of an AI coding tool.
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!
Contents
| Name | Description | License | Service |
|---|---|---|---|
| bcf | Library to read and write BCF-XML and query OpenCDE BCF-API modules | LGPL-3.0-or-later |   |
| bonsai | Add-on to Blender providing a graphical native IFC authoring platform | GPL-3.0-or-later |    |
| bsdd | Library to query the bSDD API | LGPL-3.0-or-later |  |
| 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 |  |
| ifc5d | Report and optimise cost information from IFC | LGPL-3.0-or-later |  |
| 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 |  |
| ifcclash | Clash detection library and CLI app | LGPL-3.0-or-later |  |
| ifcconvert | CLI app to convert IFC to many other formats | LGPL-3.0-or-later* |   |
| ifccsv | Library and CLI app to export and import schedules from IFC | LGPL-3.0-or-later |  |
| ifcdiff | Compare changes between IFC models | LGPL-3.0-or-later |  |
| ifcedit | CLI wrapper for ifcopenshell.api IFC model mutation functions | LGPL-3.0-or-later |  |
| ifcfm | Extract IFC data for FM handover requirements | LGPL-3.0-or-later |  |
| ifcmax | Historic extension for IFC support in 3DS Max | LGPL-3.0-or-later* | |
| ifcmcp | MCP server for querying and editing IFC building models | LGPL-3.0-or-later |  |
| ifcopenshell-python | Python library for IFC manipulation | LGPL-3.0-or-later* |         |
| ifcpatch | Utility to run pre-packaged scripts to manipulate IFCs | LGPL-3.0-or-later |  |
| ifcquery | CLI tool for querying and inspecting IFC building models | LGPL-3.0-or-later |  |
| ifcsverchok | Blender Add-on for visual node programming with IFC | GPL-3.0-or-later |  |
| ifctester | Library, CLI and webapp for IDS model auditing | LGPL-3.0-or-later |  |
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* |