[OpenSCAD] Fwd: [Pythonocc-users] Draft of the look and feel of a simple pythonic API for CSG

Bryan Bishop kanzure at gmail.com
Sun Feb 21 21:30:05 CET 2010

---------- Forwarded message ----------
From: Thomas Paviot <tpaviot at gmail.com>
Date: Sun, Feb 21, 2010 at 2:24 PM
Subject: Re: [Pythonocc-users] Draft of the look and feel of a simple
pythonic API for CSG
To: Bryan Bishop <kanzure at gmail.com>

2010/2/21 Bryan Bishop <kanzure at gmail.com>
> On Sun, Feb 21, 2010 at 1:59 PM, Thomas Paviot <tpaviot at gmail.com> wrote:
> > Hi Bryan,
> Hey Thomas. Thanks for the quick reply.
> > *Very* intersting thread, thank you for opening it.
> had to be done
> > The topic you're talking about is still an open issue in CAD and
> > contributions from the open source community would certainly be a great
> > thing. However, it's not only a technical problem (in terms of
> > implementation), but rather a scientific one. As far as I know, a good
> > starting point is the second edition of the AP203 STEP application protocol,
> > especially the ISO10303-55 (‘Procedural and hybrid representation’). Being
> > able to implement this part of the standard in a scripting langage would
> > already be a huge step.
> Yes, absolutely. I do not have access to the ISO documentation on
> STEP. Maybe you can send a few files my way to help me out? There is
> one other resource that I am aware of- namely, the STEP export API in
> the OpenCASCADE source code. From this, it is possible to extract the
> valid entities that can be found in a STEP file in the EXPRESS
> language. But then you have the issue of adopting OCC's peculiar
> standard or peculiar implementation of STEP. Here's a skeleton of STEP
> features that I figured out by looking at the OCC source:
> http://designfiles.org/~bryan/step_importer.py
> > I think this approach would certainly be the easiest way to get started: the
> > STEP data model has been widely discussed and validated.
> Right now what we need most are the ISO 10303 documents. Otherwise I
> suspect nothing will happen. Whether or not this could be used to make
> an API is also another issue- I suspect so, but maybe we should forge
> ahead even if we can't get the ISO docs?
> - Bryan

You'll have to buy the CD in order to have documentation. However,
there's a webpage dedicated to AP203ed2 here:
The EXPRESS data model file can be browsed at:
I learnt most of the STEP standard by reading the EXPRESS files.

> http://heybryan.org/
> 1 512 203 0507

- Bryan
1 512 203 0507

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