FreeCAD Model Airplane Design Workbench

A workbench with tools to help generate model airplane structures in FreeCAD

Development

Following are some tips to set up the project and have hot reloading and code assistance to improve development productivity

Developing a FreeCAD Workbench with Hot Reloading

• set up a new workbench according to the workbench template available on Github

  • be sure to use python modules and packages that use "init.py" so that package paths get automatically imported

• to develop the workbench efficiently, softlink the top-level module folder into the FreeCAD user modules directory

  • ln -s ${WB_DEV_PATH}/MyWorkBench ~/.local/share/FreeCAD/Mod where "MyWorkBench" is the top-level folder of your workbench, containing all the artifacts that are ingested by FreeCAD to instantiate your workbench
  • when working on your workbench, import your top level workbench module to bring it into FreeCAD. doing so will allow you to reload it as follows:

import my_wb_module

# experiment, make changes to your source, then reload them
from importlib import reload
reload(my_wb_module)

Vscode Type Hinting

• install FreeCAD into the /opt folder as an exploded AppImage archive; we need to install FreeCAD as an exploded archive so that we can obtain Python library paths, and provide them to vscode for python code analysis
  • ./FreeCAD*.AppImage --appimage-extract
    • this will usually create a default folder name like "squashfs", which you should rename to something more recognizable
• in the workbench folder, create a hidden folder ".vscode", and inside it create a file called "settings.json"
• in the file settings.json, create the following properties

{
"python.analysis.stubPath": "FREECAD_STUB_PATH",
"python.analysis.extraPaths": [
    "LIB_PATH1",
    "LIB_PATH2",
    ...
    "LIB_PATHN"
]
}

• in python.analysis.extraPaths, fill in the entire python path set from the FreeCAD python console. You can obtain this by starting FreeCAD, going to the python console, and entering the following:

import sys
print(sys.path)

• you can use a text editor to reformat the path strings in a manner suitable for entry into the extraPaths variable above

  • format to get each path on its own line for viewing ease (replace ", " with ", \n" in a text editor)
  • replace single-quite string delimiters (`) with double-quotes (")
  • note that this will also contain the paths to installed workbenches that are usually in the user's local folder; if you add or remove workbenches from within FreeCAD, you may need to update the paths to include the changes

• Some of the FreeCAD work benches are provided by native libraries, and require stub files to enable code assistance. To generate stubs, do the following:

  • create a folder freecad-stub-gen, then change directory inside it
  • checkout the FreeCAD source, git clone https://github.com/FreeCAD/FreeCAD.git
    • inside the FreeCAD folder, use git to checkout the branch or tagged version of FreeCAD that corresponds to the version you will be using to develop your workbench
  • checkout the repository freecad-stubs, git clone https://github.com/ostr00000/freecad-stubs, and change to the latest available tagged version
    • note that you may need to install Python 3.12 or later. If your system doesn't have Python 3.12, you can install it from the deadsnakes PPA on Ubuntu
  • follow the directions in the freecad-stubs README to generate stubs for the native FreeCAD modules
    • Note, that you may need to add freecad-stubs/lib to your PYTHONPATH - this is a step that is omitted in the README directions in the repository
  • after generating the stubs, copy it to a sub-folder called stubs underneath your exploded AppImage FreeCAD installation; then provide the new stub directory (e.g., /opt/freecad-0.21.2-appimage/stubs) as the FREECAD_STUB_PATH variable noted above
    • this is a convenience, so that the generated stubs are available in a single place for other python workbench or macro projects

• in vscode, set the interpreter path to the python binary contained in your exploded AppImage archive; while not strictly necessary, this ensures the greatest consistency with the configured libraries for type hinting