IFC Export & Import

Export

toIfc(model, meta) walks the model and returns IFC-SPF bytes.

import { toIfc } from 'brepjs-bim';

const result = await toIfc(model, {
  applicationName: 'office-tool',
  applicationVersion: '1.0',
  author: { givenName: 'Jane', familyName: 'Doe', email: 'jane@example.com' },
  organizationName: 'Example Ltd',
});
if (result.ok) await writeFile('model.ifc', result.value);

• Schema: IFC4 by default; pass ifcSchema: 'IFC4X3' to target the newer schema.
• Units: specs are millimeters; the writer emits SI metres (toIfcLengthM / toLengthMm convert explicitly).
• Owner history: author and organization metadata become a proper IfcOwnerHistory.
• Determinism: element GUIDs and local id counters are stable, and creationTimestamp defaults to the epoch, so re-exporting an unchanged model yields byte-identical content (modulo the timestamped FILE_NAME header line).

toIfcValidated runs export plus the validation suite in one call and returns the bytes together with the reports.

Import

fromIfc(bytes) parses an IFC file (via web-ifc) into an ImportedModel: elements with geometry, property sets, materials, and the spatial tree.

import { fromIfc, disposeImportedModel } from 'brepjs-bim';

const imported = await fromIfc(bytes);
if (imported.ok) {
  const model = imported.value;
  // model.elements, model.spatialTree, model.psets, ...
  disposeImportedModel(model);
}

Imported geometry pins kernel memory; call disposeImportedModel when done. geometry.solids owns every reconstructed, World-placed Body item. geometry.completeness reports COMPLETE, PARTIAL, or NONE. geometry.fidelity reports the least faithful retained item. Raw mesh siblings are combined in meshVertices and meshIndices. The geometry.solid compatibility property borrows the same handle only when a COMPLETE Body contains one solid; it is null for multi-item, partial, and missing Bodies. Never dispose the alias separately. Complete Bodies expose the component-wise aggregate bounds and the sum of item volumes as volumeMm3. Both become null when aggregate measurement fails. Both are also null when completeness is PARTIAL or NONE. For header-level inspection without geometry, SpfReader parses the STEP structure directly.

The IFC4X3 importer recognizes Bridge and Bridge Part nodes in spatialTree and imports IfcEarthworksFill as EARTHWORKS_FILL. Each imported product exposes spatialStructureExpressId for its direct Storey or civil Spatial Part; storeyExpressId remains as a compatibility alias.

Round-tripping

Export → import → compare is a first-class operation, not a demo: checkRoundTrip(bytes) re-reads an exported file and reports entity counts and losses, and the test suite gates on semantic round-trip fidelity (identity, relationships, psets, containment, and volumes within 0.5%). If you build on the families layer, GlobalIds additionally survive source-level edits: they derive from key paths, not insertion order.