ifclite-geom 4.2.0

Native ifc-lite geometry-data export for Python (welded, IFC Z-up, world coords).

ifclite-geom

Native ifc-lite geometry tessellation for Python. It turns an IFC file into per-entity triangle meshes with no Node, no WASM, and no subprocess: the Rust geometry kernel runs directly inside the Python process.

Meshes come back welded, IFC Z-up, in absolute world metres, keyed by IFC STEP id (occurrences only). This is the analysis-ready export, distinct from the render-oriented GLB the viewer uses.

Install

pip install ifclite-geom

Prebuilt wheels ship for CPython 3.9+ on Linux (x86_64, aarch64), macOS (Apple silicon and Intel), and Windows (x64). No Rust toolchain needed.

Quick start

The module is ifclite_geom and exposes two functions. Both take the raw IFC file as bytes and return the same geometry; they differ only in the output format.

import ifclite_geom
import numpy as np

with open("model.ifc", "rb") as f:
    ifc_bytes = f.read()

data = ifclite_geom.geometry_data_buffers(ifc_bytes)

print(data["element_count"], "elements")
print("up axis:", data["up_axis"], "| units:", data["units"])
print("rtc offset:", data["rtc_offset"])

for step_id, el in data["elements"].items():
    verts = np.frombuffer(el["vertices"], dtype=np.float64).reshape(-1, 3)
    faces = np.frombuffer(el["faces"],    dtype=np.uint32 ).reshape(-1, 3)
    print(step_id, el["ifc_type"], el["global_id"], verts.shape, faces.shape)

Prefer no numpy dependency? Use the JSON variant, which returns the same data as arrays of numbers:

import ifclite_geom, json

doc = json.loads(ifclite_geom.geometry_data_json(ifc_bytes))
first = next(iter(doc["elements"].values()))
print(first["ifc_type"], first["vertices"][0])  # [x, y, z] in metres

API

geometry_data_buffers(ifc_bytes: bytes) -> dict

The fast path. Vertices and faces come back as raw little-endian byte buffers so you can hand them straight to numpy.frombuffer with zero parsing.

{
  "up_axis": "Z",            # always Z (IFC native)
  "units": "m",              # always metres
  "rtc_offset": [x, y, z],   # geo-reference offset already folded into vertices
  "element_count": 1234,
  "elements": {
    <step_id:int>: {
      "ifc_type":  "IfcWall",
      "global_id": "3vB2...",   # may be None
      "name":      "Basic Wall:...",  # may be None
      "color":     [r, g, b, a],      # 0..1
      "vertices":  <bytes>,           # f64 little-endian, xyz triplets
      "faces":     <bytes>,           # u32 little-endian, triangle indices
    },
    ...
  }
}

Decode the buffers with:

verts = np.frombuffer(el["vertices"], dtype=np.float64).reshape(-1, 3)  # (V, 3)
faces = np.frombuffer(el["faces"],    dtype=np.uint32 ).reshape(-1, 3)  # (F, 3)

geometry_data_json(ifc_bytes: bytes) -> str

The same geometry as a readable ifc-lite-geometry-data JSON document (a string; call json.loads on it). Vertices are [x, y, z] arrays and faces are [a, b, c] index arrays, so no numpy is required. Each element also carries global_id and name when the source entity has them.

Notes

• One mesh per element. Per-material submeshes of an element are merged into a single indexed triangle soup, keyed by its IFC STEP id.
• Coordinates are absolute world metres. The per-element local frame and the model RTC offset are folded back into every vertex. For geo-referenced models rtc_offset is non-zero; subtract it if you want f32-friendly local coordinates.
• Welded and indexed. Coincident corners are merged (1 micron grid), so closed-mesh consumers (volume, watertightness checks) work directly.
• Occurrences only. Type-product / RepresentationMap geometry is not emitted, matching what occurrence-based tessellators produce.
• Errors surface as RuntimeError (geometry pipeline failure) or ValueError (JSON serialization failure).

Examples

Runnable scripts live in examples/:

• quickstart_numpy.py - load a file and inspect meshes via numpy.
• dump_json.py - write the JSON document to disk.
• export_obj.py - write every element to a single Wavefront .obj (numpy only, no extra deps).

License

MPL-2.0. Part of the ifc-lite project.