[freearchitecture] Re: x3d-cad vs. step

[Terry Hancock]

Lars Grobe wrote:

>Well, the creation of that library is good news. Does the step licensing
>allow other apps to link to that library without paying the license fee for
>the parts of step implemented? I think it is hardly possible to convince
>authors of independent open source tools to pay for their free work, but if
>they could link against a library, this might be the approach to encourage.
>  
>
OKAY.  This is an important point:

* There is NO fee-based "STEP licensing". If there were, it would not be
   in any way an open standard, and we'd have to just drop it (or
   lobby for the licensing terms to be changed, whichever you think
   is easier!)

* There IS a fee to download the *official* documentation for STEP,
   which, AFAIK, is copyrighted, which means that even if I were to pop
   for said $10,000 (I haven't got that much so this is entirely
   hypothetical), I still couldn't post the results on the web, which
   makes them next to useless for a community based project.  So I
   don't propose that anyone pays the fees for the standards documents.

*  OTOH, you don't strictly need the "standards document" if you have
   the source, and code to automatically extract what you need from
   the source.  I've been told by the ISO committe members and a member
   of EXFF that the source was all released free, with this intent (at
   least for their part).

* This last point is what EXFF is doing.  IIRC, they already have an Express
   parser, but I'm not sure what their complete toolset is.

* I've already seen the NIST C implementation, but I think the EXFF parser
  either already supercedes it, or is meant to.

* STEP can mean many things, but the important thing (to me) is the schema
   for the major "application protocols".   There are useful standards 
for both
   2D and 3D CAD included.   EXFF can, if I understand correctly, 
convert the
   Express schemas into various kinds of representations, including XML,
   which is the obvious target for a modern free CAD standardization 
project.

* So when I say "use STEP", I really mean "use a file format automatically
   derived from the STEP schema for the important application protocols".

>I digged a bit in the x3d environment (well, that is already to much said,
>in fact my information consists mainly of one email). The x3d-cad
>development seams to mainly target export from cad to other tools at the
>moment. There is no big development going on to create a full cad-format in
>cad as far as I understood. That is really sad to hear, as I would like to
>have a x3d-based format (just imagine that you could use every x3d-browser
>plugin to present models with all the nice 3d-support available for x3d/vrml
>etc). So using x3d might mean that the further development to a full cad
>format had yet to be done.
>
>Another question, as there is a BRL-CAD developer on board - I wonder if it
>was possible to plug-in an application like BRL-CAD into another. The reason
>I ask is that, while BRL-CAD is said to be a very strong solid modeler, it
>has not much in common with other tools an architect is used too. So in my
>opinion one promising way to go would be to use BRL-CAD for solid
>operations, but from another GUI, together with other tools (Blender for
>meshes, Pythoncad for 2d-drawings, Scribus for layout, ...). So it would be
>necessary to use the engines of these applications on a shared model and
>from an more or less independently developed GUI. Is this just a naive idea?
>  
>
No, I agree. See my other message about "small tools" versus "monolithic
applications" -- I think the free software analog to a large monolithic
CAD application will surely be many smaller pieces.  The point is,
that with the appropriate effort in standardizing interchange between
packages, and some GUI sweetening, a group of smaller, independently
produced tools can become an "environment" or "stack" from the users'
PoV.

This also has the advantages that there doesn't have to be just one of
each piece, and that in many cases it will be better to use existing tools
than to re-invent them as part of some other package.  Steve Hall says
that spreadsheets and word processors are used more than the internal
CAD tools for schedules and cost estimates, etc.  So, don't implement
them -- just connect them. We already have open document standards
going through ISO approval -- there are viable spreadsheet and word
processor standards to be used in communicating between applications.

As background, consider the different approaches taken by Gnome,
KDE, and OpenOffice in replacing Microsoft Office: Gnome collected a bunch
of separate (mostly pre-existing) applications, KDE shephards the
construction of projects based on its libraries, OpenOffice tries to do it
with one monolithic project.  It's debatable which is the best tactic, but
all three are at least moderately successful.

Cheers,
Terry

-- 
Terry Hancock (hancock at AnansiSpaceworks.com)
Anansi Spaceworks http://www.AnansiSpaceworks.com