Dear Rhino/Grasshopper developers thanks for Rhino 6, many useful improvements, render, Rhinocommon functions … but there is an old subject Polyline Offset see this thread :
Are there some news about Polyline offset ?
I know Clipper is a good solution for Grasshopper and Rhino.
Update : @pascal it is not a Grasshopper question more a Rhino core function. There is a reliability problem with offset Polyline. It doesn’t work on some the cells which are simple polygon (see the picture).
The same as in Grasshopper, I used Rhino 6 and offset multiple
And Clipper solution
offset fail.gh (6.9 KB)