[PythonCAD] PythonCAD Digest 3D

Art Haas ahaas at airmail.net
Mon Dec 18 02:00:45 CET 2006

On Sun, Dec 17, 2006 at 01:31:48PM -0800, NickW wrote:
> >I also wanted to know the direction the pythoncad would take
> >for the future . . . ie will there be 3D objects incorporated
> in it or any .dwg and .dgn support
> That is a plan. I've run this program, autocad, casmate, beta pagemaker
> with rotating line input formats and another auto design prog. I know
> it's possible and the steps following acceptance of deliverables is
> crucial to answering your question.


Right now I'm still concentrating on getting the basic 2-D functionality
working, so for the immediate future I'm not planning to try and add
3-D functionality. I believe the program currently has a number of
design limitations that would need resolving before a move to 3-D could
be attempted. I definitely want PythonCAD to handle DWG and DXF files;
I don't know what '.dgn' is but I'll guess another AutoCAD file format.

> Tooling is another challenge that will likely take form outside
> pythoncad but fits with its goals. What if you have a program that makes
> tool call outs, for example, and run cnc? I've asked Art Haas about this
> -- no response.

Sorry about that. Extending PythonCAD to handle CNC machining would
be an incredible feature, but it is one I will definitely need outside
help in achieving. One possible approach is to add menus/dialogs
that are site-specific and loaded when the program starts. I've always
envisioned the program to have this level of customizability similar
in the way that people have extended XEmacs/Emacs and the various
lisp-based addons for AutoCAD.
> I'm in the engine block, dimensioning & tolerances and rocket science
> group. We are open source.


> >There are basic functions available in it while I miss the Snapping
> >part a lot.

PythonCAD will automatically connect to points in a layer, and I'd like
to add feature like snapping to segment midpoints and other useful
snap-to destinations. What does 'snapping part' do?

> Do you mean snap to a straight line or bezier curve? When crafting lines
> in the operating environment I believe line and curve are two actions
> following generation of a routine. Its job is to accept input, plot and
> report x and y where you're shaping or cutting.

One drawing entity I started working on was a NURBS entity for providing
nice smooth curves but things got bogged down. There is code in
PythonCAD right now for an Ellipse entity but no means of creating such
an entity or drawing it. Eventually both of these entities will be
in the program.

Art Haas
Man once surrendering his reason, has no remaining guard against absurdities
the most monstrous, and like a ship without rudder, is the sport of every wind.

-Thomas Jefferson to James Smith, 1822

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