[x3d-public] file converter based on pythonocc

Sun Apr 19 09:35:15 PDT 2020

OpenCascade is the only realistic, open-source option to digest step
format. It is a c++ library, so there is a need for backend/server
side processing. The easiest option for that is docker and there is a
preconfigured, working docker image with both, a working OpenCascade
installation, and the pythonocc wrapper which also adds some
functionality such as x3d export. Also, python is faster to iterate
than c++, and jupyter gets you even more convenience.

I added a small example jupyter notebook which work on top of
https://mybinder.org/v2/gh/tpaviot/pythonocc-binderhub/master to
https://github.com/andreasplesch/OCCToX3D, and an example x3d
conversion as proof of concept.

I also discovered that OpenCascade supports generally compilation to
wasm using emscripten. So longer term it may be possible to compile
the OCC libraries required for loading, triangulation and exporting
(to VRML) to wasm/ecmascript, and get a completely client based
solution. However, the content typically is large and complex, and
there is a lot of computation involved. So in practice it may not work
out. A main advantage would be that users would not have to trust a
remote server with their valuable content.

I think next I will try for a bit if is feasible to use the OCC VRML
writer, rather than the relatively simple pythonocc x3d exporter. The
python wrapper seems to exist but I do not think there is an example.

-Andreas

On Sat, Apr 18, 2020 at 9:47 PM John Carlson <yottzumm at gmail.com> wrote:
>
> X3DJSAIL has www.web3d.org/x3d/stylesheets/java/src/org/web3d/x3d/jsail/X3DLoaderDOM.java which supports DOM scenegraphs.
>
> Examples of usage are here:
>
> www.web3d.org/x3d/stylesheets/java/nashorn/examples/Json.js
> www.web3d.org/x3d/stylesheets/java/nashorn/examples/Nashorn.js
> www.web3d.org/x3d/stylesheets/java/nashorn/examples/X3d.js
>
> Basically, the examples parse JSON into a document using  X3DJSONLD.java then convert DOM into a X3DJSAIL scenegraph.
>
> So to answer your createX3DFromString() question, if you start with JSON, I think you could get a X3DJSAIL scenegraph from a JSON string using the X3DJSAIL-like python API (the one we got to work with Jupyter).
>
> Otherwise, you probably have to wait for enhancements to x3d.py.  It looks like toXML is supported in x3d.py currently.  One could use a stylesheet X3dToPython.xslt to convert XML to Python.
>
> So one could use the stylesheet in a web program (GL with that!) to output python.  Then you would have to use something like eval (ugh!).
>
> John
>
>
>
>
> On Sat, Apr 18, 2020 at 5:20 PM Andreas Plesch <andreasplesch at gmail.com> wrote:
>>
>> Thanks for the interest. I initialized a project at
>>
>> https://github.com/andreasplesch/OCCToX3D
>>
>> The wiki has some collected info and a short outline. The wiki is
>> editable by anyone.
>>
>> pythonocc has a method to generate X3D xml. It is a simple Shape with
>> a TriangleSet, nothing sophisticated. If x3d.py would have  a
>> createX3DFromString() function, it would be possible to use x3d.py to
>> enhance the generated X3D. But I do not think x3d.py has that. But
>> x3d.py may come in handy in other ways.
>>
>> The first goal is to add a simple jupyter notebook to the repo based
>> on the available pythonocc docker image which demonstrate how to load
>> step and output X3D.
>>
>> Any feedback or ideas welcome, using Issues on the project or here,
>>
>> -Andreas
>>
>>
>>
>>
>> On Sat, Apr 18, 2020 at 1:27 PM Don Brutzman <brutzman at nps.edu> wrote:
>> >
>> > Hi Andreas, sounds like a great idea to me.  Here are some peripheral points of support.
>> >
>> > Last weekend i updated and deployed the x3d.py package (sometimes called X3DPSAIL) at
>> >
>> > [1]     Python Package Index (PyPi) x3d 0.0.25
>> >         Package support for Extensible 3D (X3D) Graphics International Standard (IS)
>> >         https://pypi.org/project/x3d/
>> >
>> > [2]     Python X3D Package x3d.py,X3D Python Scene Access Interface Library (X3DPSAIL)
>> >         https://www.web3d.org/x3d/stylesheets/python/python.html
>> >
>> > "The x3d.py Python X3D Package supports programmers with Python interfaces and objects for standards-based X3D programming, all as open source.
>> > The presentation *Python X3D Package Implementation* provides an overview and shows examples."
>> >
>> > [2.1]   Python X3D Package Implementation
>> >         https://www.web3d.org/x3d/stylesheets/python/documents/PythonX3dPackageImplementation.pdf
>> >
>> > So you would use this library for model creation and data-driven improvement, no need to reinvent X3D data structures or methods.
>> >
>> > This is autogenerated from X3DUOM so it will always stay in sync with latest/greatest X3D4.
>> >
>> > We've done some preliminary work with Jupyter notebook, listed there.  Lots of potential projects in TODO section.
>> >
>> > [2.2]   X3DPSAIL: Jupyter notebook, TODO
>> >         https://www.web3d.org/x3d/stylesheets/python/python.html#Jupyter
>> >         https://www.web3d.org/x3d/stylesheets/python/python.html#TODO
>> >
>> > For pythonocc conversion efforts, will be happy to ensure that
>> > a. all improvements to API are applied,
>> > b. ensure that validation of all scene-graph inputs remains rigorous,
>> > b. utility methods are added for easy use together,
>> > d. examplar conversion models are properly saved in X3D Examples Archive,
>> > e. Whatever else!
>> >
>> > Looks like there is vast potential here.  Hoping folks start picking it up and applying capabilities.
>> >
>> > Have fun with X3D Python!  8)
>> >
>> >
>> > On 4/17/2020 5:15 PM, Andreas Plesch wrote:
>> > > Did somebody put together an x3d converter based on pythonocc ?
>> > >
>> > > Here is an example:
>> > >
>> > > https://senties-martinelli.com/software/cad-viewer
>> > >
>> > > It could convert  step, stp, igs, iges, obj and stl formats. Format
>> > > import and export is only a small subset of pythonocc
>> > > (https://github.com/tpaviot/pythonocc-core) but I think just making
>> > > this functionality easy to use with a dedicated converter could be
>> > > really valuable.
>> > >
>> > > In the end, I think a  web service just for conversion would be most useful.
>> > >
>> > > I played with the Jupyter notebook and could generate with only a few lines x3d.
>> > >
>> > > And there are ways to generate a standalone webapp from a notebook:
>> > > https://discourse.jupyter.org/t/how-to-transform-a-jupyter-notebook-into-a-webapp/758/6
>> > >
>> > > That could be quick way to offer a web service.
>> > >
>> > > Have there been attempts of this kind ? Would there be interest in a
>> > > open source github hosted project ?
>> > >
>> > > -Andreas
>> >
>> > all the best, Don
>> > --
>> > Don Brutzman  Naval Postgraduate School, Code USW/Br       brutzman at nps.edu
>> > Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA   +1.831.656.2149
>> > X3D graphics, virtual worlds, navy robotics http://faculty.nps.edu/brutzman
>>
>>
>>
>> --
>> Andreas Plesch
>> Waltham, MA 02453
>>
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>> x3d-public at web3d.org
>> http://web3d.org/mailman/listinfo/x3d-public_web3d.org

-- 
Andreas Plesch
Waltham, MA 02453