OpenBim.Ifc 0.1.1

OpenBim.Ifc (.NET)

Read, edit, validate and write IFC files from .NET: C#, F#, or a Revit, Navisworks, Tekla or Dynamo add-in. A thin binding over the openbim-ifc Rust crates, through their versioned C ABI; the native library ships inside the package.

dotnet add package OpenBim.Ifc

Documentation: .NET guide · source and issues

using OpenBim.Ifc;

using var model = IfcModel.Open("model.ifc");
foreach (var wall in model.IdsOfTypeIncludingSubtypes("IfcWall"))
{
    Console.WriteLine($"#{wall} {model.Attribute(wall, 2)}"); // 'Wall'
    model.SetAttribute(wall, 2, new Value.Text("Renamed"));
}
File.WriteAllBytes("out.ifc", model.Write());

Platforms

The package carries the native library for win-x64, win-arm64, linux-x64, linux-arm64, osx-x64 and osx-arm64, all 64-bit. A .NET application picks its runtime's copy itself. A .NET Framework project gets the Windows libraries copied into its output by the package's build targets, and the assembly loads them from next to itself, so an add-in needs no RuntimeIdentifier and no copy step.

Values

Attribute values are a closed record hierarchy, one case per STEP form: Value.Null ($), Value.Derived (*), Value.Bool, Value.Unknown (.U.), Value.Integer (64-bit), Value.Real, Value.Text, Value.Binary, Value.Enum, Value.Ref (#42), Value.List and Value.Typed (IFCLENGTHMEASURE(2.5)). They keep every distinction IFC makes, so a file read and written back through .NET is unchanged; they compare by value, lists included.

Errors

Every refusal throws IfcException with a stable Code (parse, missing-entity, invalid-value, unsupported-schema, ...) shared with the JavaScript, Python and C bindings, and the C ABI's Status. A refused edit leaves the model unchanged.

Models and threads

IfcModel is IDisposable: dispose it to release the native model, or the finalizer will. Calls on one model are serialised by the library, so a model may be shared between threads; calls on different models run in parallel.

Scope

The record model -- entities, attributes by position and by name, the STEP codec, exact and subtype queries -- plus lenient reads (ParseOptions), the STEP header, validation, ifcXML, the reachability lint, the read-only domain views (property sets and quantities, the spatial tree, classification, materials, systems, cost, georeferencing) as C# records, writing property sets and quantities as one checked transaction (SetProperties), checked against the embedded PSD/QTO catalog, and creating entities as one checked transaction (Author with AuthorOps: entities by type and named attributes, the spatial structure, placed, contained and typed products, removal with relationships). Geometry is not bound yet.

Build from source

The package is C# in dotnet/; the Cargo crate around it holds its version, changelog and the tests that hold the C# declarations to the C header and the shared records. With the .NET 8 SDK and Rust:

python3 crates/openbim-ifc-dotnet/scripts/check-dotnet.py

builds the C ABI library for this machine, packs the .nupkg and runs the C# suite against it from a fresh project.

License

AGPL-3.0-or-later; the package carries LICENSE and NOTICE. See the repository's LICENSING.md.