IfcOpenShell WASM

Live version: http://wasm.ifcopenshell.org

This is a technological preview of an IfcOpenShell WASM python module for use in pyodide. It uses emscripten to compile the C/C++ (of the python interpreter, IfcOpenShell and its dependencies respectively) into a WebAssembly (WASM) module. WebAssembly can be used in the browser or other JavaScript runtimes such as NodeJS.

Demo

Draw polygonal walls and place door and windows by using the tool panel on the left

Open existing .ifc models and improve accessibility by adding doors

Save .ifc models and import in any compatible tool

FAQ

• Is this some half-baked attempt to compete with Bonsai?

  By all means no. And, actually, it's the same code under the hood, namely the IfcOpenShell API calls such as root.create_entity, geometry.add_wall_representation and geometry.add_window_representation.

Approach

This approach of supporting IFC within the browser is rather heavy as it depends on a python interpreter loading the wasm-compiled monolithic IfcOpenShell wheel on demand. But nevertheless, we see this as the most powerful approach of enabling IfcOpenShell in the browser.

Over time, Python code has surpassed C++ as the predominant language in IfcOpenShell and has become the defacto standard for the IfcOpenShell API. We wouldn't want browser-based usage to require duplicating this powerful set of APIs.

Wrapping the full IfcOpenShell-python module results in a feature rich module, that makes for example, IFC validation, visualization, but also authoring a breeze because any pre-existing pure python module can be leveraged.

Technical usage

Pyodide proxy objects

Allows direct usage of python objects in JavaScript code.

let ifcopenshell_geom = pyodide.pyimport('ifcopenshell.geom');
let s = ifcopenshell_geom.settings();
s.set('weld-vertices', false);

Python code evaluation by Pyodide

Allows running actual python code with the ability for JavaScript to easily reflect on global variables.

pyodide.runPython(`
from context import Context
import numpy as np
modelObject = Context()`);

In-line python code using PyScript

Allows running inline python code in HTML script tags

Limitations

• Performance of loading and running code is not optimal.
• C++ exception handling in the IfcOpenShell dependencies seems to cause issues in WASM, because the OpenCASCADE failures do not inherit from std::exception