Re: gEDA-user: Metric units

[DJ Delorie <dj@xxxxxxxxxxx>]

> Didn't we come to the view at some point, that using a sufficiently
> small metric unit internally would work fine?
> 
> (Due to the definition of 1" = 2.54cm allowing us to precisely specify
> both metric and imperial units, given a sufficiently small metric unit?)

Changing the internal units of PCB is not practical at this time.  I
think we calculated we'd need to maintain micrometer precision to
preserve the old "high resolution" units.  That means absolutely no
more 16-bit coordinate values (oh, darn! ;) and we'd have to be a lot
more careful about overflow.  Those, however, are technical problems.

I did add syntax to the file format to allow you to specify values
*with units* so we can at least have metric-based element definitions.
They'd still be converte to pcb's inch-based internal units, but
perhaps in the future, we can void a lossy conversion.  Converting the
whole library... no, we'd need to *rebuild* the whole library using
"native" units for each part (mm, mil, etc) would be a huge
undertaking.

But given that some parts (like SOJ or DIP) are specified in terms of
inch units, I think the whole concept of a "metric only library" is
rather pointless.  I think what the OP really wants is not what the OP
asked for.


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