fast_ctd - Fast CAD to DAGMC

This is a Python package for the fast conversion of STEP files to DAGMC models (.h5m files).

This package wraps certain C++ modules from the following projects that enable this conversion:

• overlap_checker
• occ_faceter

And exposes a Python interface to them using nanobind.

Quick start

This project requires the following packages pre-installed:

• cmake
• OpenCASCADE 7.8.0 or later
• MOAB 5.0.0 or later

The recommended way to install these dependencies is to use conda and can be installed with the following (openmc bundles MOAB):

conda install -c conda-forge 'openmc>=0.15.0=dagmc_*' 'occt>=7.8.0=all_*' cmake

Use pip to remotely install the package:

pip install fast_ctd@git+https://github.com/Fusion-Power-Plant-Framework/fast_ctd@main

or clone the repository and install it locally:

git clone https://github.com/Fusion-Power-Plant-Framework/fast_ctd.git
cd fast_ctd
pip install .

Development installation

Development of this package is done in a conda environment.

To create the environment, run:

conda env create -f conda/environment.yml

This will create a conda environment called fast_ctd. It locally installs the package in editable mode (meson is used to compile the C++ code with nanobind to create the extension under the hood).

Activate the fast_ctd environment (or set it as the default interpreter in your IDE):

conda activate fast_ctd

then try running an example:

cd examples
python stp_to_dagmc_workflow.py

Changing the C++ source

The editable install of the package (included in the conda environment.yml) means you can edit the C++ source code and run the Python code without needing to reinstall (rebuild) the package. nanobind automatically detects changes and recompiles the extension when you run the Python code.

However, changing some files (for example binding.cpp) will require a reinstall, which can be done with:

pip install -e .

nanobind will throw an error when you try to run the Python code without reinstalling after changing files that require it.

Meson compilation (directly)

Sometimes it's useful to test the meson compilation directly, run this once:

meson setup --wipe builddir
meson compile -C builddir

and then

meson compile -C builddir

after that.