I have moved on from learning basic part design and scripting in FreeCAD and now want to tackle assemblies.

Following on from my previous post, Building FreeCAD with 3DConnexion Support on macOS using Conda, this post presents similar instructions for building the very promising Assembly3 Workbench for FreeCAD.

Again, I wanted to use the latest source AND use a 3DConnexion SpaceMouse on a MacBook Pro. Using Conda and the Conda Forge feedstock for FreeCAD makes this a scriptable, repeatable process.

Install 3DConnexion Drivers

Download and install the latest driver for macOS.

Install miniconda

curl -L -O https://repo.continuum.io/miniconda/Miniconda3-latest-MacOSX-x86_64.sh
bash Miniconda3-latest-MacOSX-x86_64.sh -b
rm Miniconda3-latest-MacOSX-x86_64.sh 
echo ". ~/miniconda3/etc/profile.d/conda.sh" >> ~/.bash_profile

Install MacOSX10.9.sdk

curl -L -O https://github.com/phracker/MacOSX-SDKs/releases/download/10.13/MacOSX10.9.sdk.tar.xz
sudo tar -C /opt/ -xf MacOSX10.9.sdk.tar.xz 
rm MacOSX10.9.sdk.tar.xz

Set SDK location for Conda

echo "CONDA_BUILD_SYSROOT:" > ~/conda_build_config.yaml
echo "   - /opt/MacOSX10.9.sdk  # [osx]" >> ~/conda_build_config.yaml

Link to SDK for Circle CI based support scripts

mkdir -p /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/
ln -s /opt/MacOSX10.9.sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs

Prepare Conda environment

conda create -n freecad_ass3 -y
conda activate freecad_ass3
conda config --add channels conda-forge
conda install conda-build -y

Get FreeCAD feedstock

git clone https://github.com/conda-forge/freecad-feedstock
cd freecad-feedstock/

Point to the Assembly3 FreeCAD Fork

The FreeCAD feedstock recipe needs to be modified to use realthunder’s FreeCAD Fork.

Edit recipe/meta.yaml and edit the following:

• the version variable: {% set version = "LinkStage3" %}
• the git_url variable: git_url: https://github.com/realthunder/FreeCAD.git

Build FreeCAD

conda build ./recipe -m ./.ci_support/osx_python3.7.yaml

Workaround failing tests

The build will finally fail with a message similar to:

Tests failed for freecad-LinkStage3-py37h7748daf_1.tar.bz2 - moving package to /Users/vectronic/miniconda3/envs/freecad_ass3/conda-bld/broken

The failed tests don’t seem to stop basic functionality working in FreeCAD and realthunder is planning to eventually fix them. In the meantime I ignore them as follows:

mv ~/miniconda3/envs/freecad_ass3/conda-bld/broken/freecad-LinkStage3-py37h7748daf_1.tar.bz2  ~/miniconda3/envs/freecad_ass3/conda-bld/osx-64/
conda index ~/miniconda3/envs/freecad_ass3/conda-bld

Install FreeCAD

conda install -c file://${CONDA_PREFIX}/conda-bld/ freecad=LinkStage3 -y

Install and build the Assembly3 workbench and constraint solver

conda install swig -y

cd ~/miniconda3/envs/freecad_ass3/Ext/freecad
git clone https://github.com/realthunder/FreeCAD_assembly3.git
mv FreeCAD_assembly3 asm3
cd asm3

git checkout f66358d
git submodule update --init slvs
cd slvs
git submodule update --init --recursive

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release -DBUILD_PYTHON=1 ..
make _slvs

cd ../..
touch py_slvs_mac/__init__.py
cp slvs/build/src/swig/python/_slvs.so py_slvs_mac/
cp slvs/build/src/swig/python/slvs.py py_slvs_mac/

cd py_slvs_mac
install_name_tool -id "_slvs.so" _slvs.so
install_name_tool -add_rpath "@loader_path/../../../../lib/" _slvs.so

install_name_tool -change "~/miniconda3/envs/freecad_ass3/lib/libpython3.7m.dylib" "@rpath/Python" _slvs.so

NOTE: If the last command didn’t work as the python library version has changed, run the following to see which library to relink to:

otool -L _slvs.so

Use it!

FreeCAD