Thanks a lot, TIG
It's been 10 years...
I think you need to replace the lines
ts=Geom::Transformation.scaling(ct, 1.0/tx, 1.0/ty, 1.0/tz) c.transform!(ts) ### reset scale
with
c.transformation*=Geom::Transformation.scaling(1.0/tx, 1.0/ty, 1.0/tz)
Because when there is a rotation transformation, it does not work correctly