mirror of
https://github.com/IfcOpenShell/IfcOpenShell.git
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Dion Moult
cd77c557e9
The previous README described a pre-instancing world (32-byte world-
coord vertices with per-vertex object_id, ObjectDrawInfo structs, EBO
reordering after BVH build, and a Phase 3 plan built around moving
draw submission to the GPU). Most of that is either gone or already
solved:
- Vertices are now 28 B local-coord; per-instance transforms live
in an SSBO read through a visible-index SSBO and gl_BaseInstanceARB.
- ObjectDrawInfo is replaced by MeshInfo + InstanceCpu + InstanceGpu.
- No EBO reorder on BVH build — the BVH is over instance AABBs and
the mesh/EBO layout is orthogonal.
- Draw-call submission is already one glMultiDrawElementsIndirect
per model; the old Phase 3 goal is met.
New content worth keeping:
- GPU instancing section documents the mesh/instance/visible/indirect
buffer contract the whole renderer hangs off of.
- Reflection-aware two-pass draw is documented (det<0 placements,
forward/reverse slice split, glFrontFace toggle).
- reorient-shells and backface culling are called out as correctness
+ perf levers with their tradeoffs.
- Phase 3 is rewritten around the actual bottleneck surfaced by
profiling: per-frame glNamedBufferSubData stalls on the visible
and indirect buffers. Includes the diagnostic methodology (empty-
screen jump to 60 fps, window/MSAA invariance, upload-comment-out
experiment) so future-me remembers why this is the next step.
- 3A (persistent mapped ring buffers, near-term) and 3B (GPU-side
compute cull, longer-term) split out with scope estimates.
- Roadmap updated: instancing / MDI / reflections / reorient-shells
/ backface cull all ticked; 3A surfaced as the next open item.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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* |