Principle stress lines

Hi Daniel,
a while ago there was a interessting discussion.

I test your definition and try to get a dome. The result looks great. Pls see attached.
Just curiosity if Kangoroo can amylase principle stress lines?
And I was wondering if this is necessary, because after form-finding step and the usual assumption of a linear relationship between force and displacement is no longer valid due to the inherent large deformations…is that correctly?