Thank you to @Stephan
x,y,z,S1,S2,S3,SN1x,SN1y,SN1z,SN2x,SN2y,SN2z,SN3x,SN3y
like we get from Abaqus or Flac3D output and creating normal vectors from stress (either the six components or using dip/ddir, for example with GridTools or Paraview) and creates arrows (from basic shape cylinders and cones), colored by each principal components. Also creates render materials so this works in Render mode (and therefore VR). A few hundred points are no problem; I wouldn’t try a million, obviously.
I put the code on GitHub https://github.com/SMArndt/RhinoPrincipalStress
