[cad-linux-dev] Re: Drawing entity
- From: Bruno Postle <bruno@xxxxxxxxxx>
- To: CAD linux development <cad-linux-dev@xxxxxxxxxxxxx>
- Date: Thu, 19 Aug 2004 18:53:28 +0100
On Thu 19-Aug-2004 at 13:22 -0400, Somerlot, Chris wrote:
>
> One thing I forgot is that there should be an entity for the
> drawing itself, that stores attributes like units, a timestamp,
> and a version.
Having to look-up an external file to discover the units of an
element is an added complexity - It would actually be really useful
to store the units at the element level and Eric just convinced me
that this is how layers etc... should be treated.
For instance, if your drawing has a base unit of metric inches, then
the nominal diameter of an M10 bolt is .3937007874015748031496062992
inches and is going to attract rounding errors - These errors would
go away if you allow a 10mm circle to be 10 millimeters and a 2x4
piece of timber to be 2x4 inches.
Timestamps can be retrieved from the file properties (or a CVS
history for much finer resolution) and I'm still voting for a
'file-format version' attribute in the elements themselves.
--
Bruno
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