[PythonCAD] An open file format for Computer Aided Design (CAD)

Eric Wilhelm ewilhelm at sbcglobal.net
Sun May 30 12:52:49 EDT 2004

# The following was supposedly scribed by
# Nikola Radovanovic
# on Sunday 30 May 2004 09:34 am:

>I think it could be interesting.

Well, here's this old saw again:)  I've been following and prodding the same 
sort of issue for well over a year now.  Art has yet to rewrite pythoncad 

Previous discussions have occurred on the cad-linux and cad-linux-dev mailing 
lists, with some deeper, more technical exploration on the #cadfs channel at 
on irc.freenode.net.  We are now currently working at hypnotizing the 
blendercoders into making this happen in blender.

I've also tried to work as much as possible into my perl modules CAD::Drawing 
and such, using them as a test-bed for the textual-file ideas and also to try 
to integrate existing file formats.  This is not easy.

So, why isn't it going anywhere?  For one, it has no corporate backing.  For 
two, I think it is going somewhere, but you have to realize the complexity 
involved in making just one good tool that works with this file-on-disk 
entity model.  Furthermore, whichever tool does it first will be stranded on 
its own island (per the autodesk plan) until it is able to read/write 
industry-standard data via import and export.

But, this island issue is no stranger to anyone who has set-out to create 
their own cad tool.  Essentially, the easiest way to save your in-memory data 
to disk is to dump it.  That's all dwg is, and the only reason that it has 
become de-facto is that it was here first (and marketing money never hurt 
such a scheme.)

My current line of thought is that the files-on-disk model has the best chance 
of takeoff as a repository where all different kinds of data are 
imported/exported by a model/drawing manager.  Thus, you have dwg, vrml, 
step, iges, pythoncad, etc all going in and out of the same place.  This 
makes the manager program capable of storing the union of all features which 
are available in all of these formats, and eventually someone will catch-on 
and rewrite their app to connect directly to the manager.

"It works better if you plug it in!" 
                                        --Sattinger's Law

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