Changing GDIR from NEGZ to POSZ in SOFiSTiK Grasshopper Axis without breaking the model

SOFiSTiK Rhino
1

Hello everyone,

I’m currently working with the SOFiSTiK Grasshopper interface and ran into an issue regarding the global Z direction when defining an axis.

By default, when creating an axis in GH, the parameter GDIR is always set to NEGZ. I understand that this corresponds to the default gravity direction in SOFiSTiK, but as this is a German project I would like to work with POSZ instead.

However, if I manually switch GDIR to POSZ, the entire model effectively becomes inverted and inconsistent (geometry, orientations, etc.), which is not what I want.

What I am trying to achieve is:

  • Keep the geometry and model orientation as currently defined in Grasshopper (Z-up),

  • But change the global gravity direction (GDIR) to POSZ,

  • Without having to manually invert or rebuild the whole model.

Is there a proper way to define or override GDIR in Grasshopper so that POSZ can be used without breaking the model?

Many thanks in advance!

Ioannis

2

Hello loannis,

Unfortunately keeping the existing model geometry and orientation while changing GDIR is not possible. GDIR affects not only the gravity direction but also the orientation of the entire model, including local coordinate systems of elements such as SARs. So switching it will invert your geometry, which is exactly what you are experiencing.

The only way to achieve what you want is to rebuild the model in the target orientation and then set GDIR POSZ in SOFiMSHC to change direction of gravity.

Thanks

Dariusz from SOFiSTiK