(2020-02-24, 18:41)Roland Melkert Wrote: Precision has always been an issue even while using all double precision variables.
The main reason is the mutation is applied as a 'difference' to all the parts in the selection.
So if the main part in the selection has been mutated a lot (or is read from low decimal count file) the rounding errors will be amplified.
Alternative might be to use 'snap all to edit grid plane' from the placement menu.
I've noticed something even stranger…I just spent a bunch of time cleaning up all the rounding errors in a model with lots of rotation in it, and the simple act of closing and then reopening the program seems to have reintroduced them. It's just a .001 difference, but it means that mirrored pairs of parts might have different decimal values, for example. (Note that I'm referring to relative positions here—the file code hasn't changed so the absolute decimal values are all still correct.)
So what causes the change from simply closing and reopening the file?