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| 1 | +# IfcOpenShell WASM |
| 2 | + |
| 3 | +Live version: http://wasm.ifcopenshell.org |
| 4 | + |
| 5 | +This is a technological preview of an IfcOpenShell WASM python module for use in [pyodide](https://pyodide.org/en/stable/). It uses [emscripten](https://emscripten.org/) 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. |
| 6 | + |
| 7 | +## Demo |
| 8 | + |
| 9 | +#### Draw polygonal walls and place door and windows by using the tool panel on the left |
| 10 | + |
| 11 | + |
| 12 | + |
| 13 | +#### Open existing .ifc models and improve accessibility by adding doors |
| 14 | + |
| 15 | + |
| 16 | + |
| 17 | +#### Save .ifc models and import in any compatible tool |
| 18 | + |
| 19 | + |
| 20 | + |
| 21 | +## FAQ |
| 22 | + |
| 23 | +- *Is this some half-baked attempt to compete with Bonsai?* |
| 24 | + |
| 25 | + 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`. |
| 26 | + |
| 27 | +## Approach |
| 28 | + |
| 29 | +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. |
| 30 | + |
| 31 | +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. |
| 32 | + |
| 33 | +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. |
| 34 | + |
| 35 | +## Technical usage |
| 36 | + |
| 37 | +### Pyodide proxy objects |
| 38 | + |
| 39 | +Allows direct usage of python objects in JavaScript code. |
| 40 | + |
| 41 | +```js |
| 42 | +let ifcopenshell_geom = pyodide.pyimport('ifcopenshell.geom'); |
| 43 | +let s = ifcopenshell_geom.settings(); |
| 44 | +s.set('weld-vertices', false); |
| 45 | +``` |
| 46 | + |
| 47 | +### Python code evaluation by Pyodide |
| 48 | + |
| 49 | +Allows running actual python code with the ability for JavaScript to easily reflect on global variables. |
| 50 | + |
| 51 | +```js |
| 52 | +pyodide.runPython(` |
| 53 | +from context import Context |
| 54 | +import numpy as np |
| 55 | +modelObject = Context()`); |
| 56 | +``` |
| 57 | + |
| 58 | +### In-line python code using PyScript |
| 59 | + |
| 60 | +Allows running inline python code in HTML script tags |
| 61 | + |
| 62 | +## Limitations |
| 63 | + |
| 64 | +- Performance of loading and running code is not optimal. |
| 65 | +- C++ exception handling in the IfcOpenShell dependencies seems to cause issues in WASM, because the OpenCASCADE failures do not inherit from `std::exception` |
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