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# Re: [femm] 3D Code (was Re: Linux and 3D)

- To: <femm@yahoogroups.com>
- Subject: Re: [femm] 3D Code (was Re: Linux and 3D)
- From: "sihang" <sh9988@mail.hz.zj.cn>
- Date: Sat, 2 Feb 2002 13:07:45 +0800
- References: <55CEB2C13D0ED511AEB400508BE917BD12BBA5@ThisAddressDoesNotExist>

    Yes, I think that Gid is a good pre-processor. But it's not free and its file format does not open(like the dxf), one can not extract the geometric data of the model from it. If I knew the file format of Gid, I would write a program to convert it to the .poly file format of Tetgen, and the pre-processor and mesh problem for a 3D code would be largely solved.

    Si Hang

    ----- Original Message -----
    From: Mark Smith <mark.smith@linx.co.uk>
    To: <femm@yahoogroups.com>
    Sent: Friday, February 01, 2002 6:09 PM
    Subject: RE: [femm] 3D Code (was Re: Linux and 3D)

    > Hi there,
    > Just a thought. I developed an electrostatic BEM solver which I built on the
    > back of GID ( http://gid.cimne.upc.es/index.html
    > <http://gid.cimne.upc.es/index.html>  ) a pre & post processor, I know it's
    > not free but it isn't expensive has a passable modeler, good mesher and
    > postprocessor with a TCL-TK extension. it allowed me to concentrate on the
    > solver code rather than the user interface.
    > This is a great user group. Thanks for FEMM.
    > Regards
    > Mark
    >
    >
    >
    > -----Original Message-----
    > From: David Meeker [mailto:dcm3c@earthlink.net]
    > Sent: 01 February 2002 05:45
    > To: femm@yahoogroups.com
    > Subject: [femm] 3D Code (was Re: Linux and 3D)
    >
    >
    > sihang wrote:
    >
    >  I would like to join the developing work on 3D version. I got some
    > experience in 2D finite element calculation, but no experience in 3D. As I
    > have encountered several problems that need a 3D solver. Now, I will
    > continue to work on the Tetgen program, make it more easy to use and more
    > robust.
    >
    >
    > Well, it looks like we could be approaching a critical mass that is big
    > enough to kick off a 3D code.  Here are some thoughts about making a 3D
    > version.
    >
    > Robin has already noted Si Hang's "Tetgen" program.  This would make a good
    > backbone for a 3D program. As Robin  has also noted, planning is key.  The
    > internal structure of the current 2D version wasn't incredibly well planned,
    > and that has made it hard to make things modular enough to be developed by a
    > team.  Opportunities for an object-oriented structure weren't really
    > exploited very well, and an opportunity to make a code that would easily be
    > modified to attack other similar problems (e.g. thermal, elastic,
    > electrostatic) was lost.  Any 3D effort would need to be structured in such
    > a way so that multiple programmers could be working on it without everyone
    > having to understand virtually everything about the way that the code works
    > to be able to make a valuable contribution.
    >
    >
    > We could use an existing front-end for a 3D solver, but the pre- and
    > post-processors are what really make or break the functionality of the
    > program.  For example, like 4/5 of the source code of femm is devoted to the
    > user interface--the technical things that the program does aren't really
    > incredibly novel.  For a 3D code, it would probably be better in the long
    > run to write and maintain a 3D user interface. Probably the preprocessor
    > could largely be an analog of the 2D version, which I originally envisioned
    > as a graphical way of entering in the information used in a Triangle .poly
    > geometry definition file.  A lot of the heavy lifting gets sorted out for
    > free by the mesh generator.  Just tagging regions with block labels makes it
    > a lot easier to do the preprocessor, because the preprocessor then doesn't
    > really have to be all that smart and keep track of the various regions in
    > the problem as the geometry is changed.  I'd like to do a similar approach
    > for a 3D code, except that one would think of the preprocessor as being a
    > graphical tool for building a Tetgen input file.
    >
    >
    > We need to define a core functionality that the program would  implement:
    >     How does user interface "work"?
    >     What type of problems are to be solved? (suggest nonlinear magnetostatic
    > and nonlinear time-harmonic as a start)
    >     What formulation is to be used? ("dive off the deep end" and suggest
    > T-Omega formulation)
    >     What sort of license will the program be developed under? (Some sort of
    > open-source license, but which one?)
    >
    >
    > How would the program be structured?  By breaking things into the
    > old-fashioned preprocessor-solver-postprocessor divisions, or just having
    > one code that envelops all aspects (e.g. like latest Quickfield version)?
    >
    >
    > We also need to define what set of programming tools will be used.  The
    > current 2D code is all MSVC++, but there are tools out there that allow for
    > simultaneous development on both Linux and Windows platforms.  Historically,
    > cross-platform development has resulted in some of the commercial magnetics
    > FEA programs having really lousy user interfaces.  However, cross-platform
    > development tools are maturing pretty rapidly, and they might now be good
    > enough for our purposes.  Candidates might be wxWindows or Fox Toolkit
    > (among others?) for getting things to compile across platforms.  And if
    > things could be made to compile on Linux machines concurrently with Windows
    > machines, we might have access to a pool of Linux programmers who are used
    > to contributing to open-source projects.  There could be a learning curve to
    > using either wxWindows or Fox, but it might be worth it in the end.
    >
    >
    > We would want to include scripting (i.e. Lua) in an integral way from the
    > start, rather than as a "retrofit".
    >
    >
    > Lastly, we need to create a skeleton of the where multiple programmers can
    > be working at the same time.  Some of the logistics could be accomplished
    > via standard CVS tools at BerliOS (or SourceForge).  A project has already
    > been created for femm at BerliOS (see
    > http://developer.berlios.de/projects/femm/
    > <http://developer.berlios.de/projects/femm/> ).  Perhaps it would be better
    > to move discussions about a 3D version over to the "Developers" discussion
    > forum on Berlios and focus the Yahoo list more on the 2D version. (N.B.: You
    > have to sign up with Berlios and become a developer for the project to get
    > access to the "Developers" forum.  There are no restrictions as far as who
    > can become a developer, and it doesn't cost anything to sign up.)
    >
    >
    > Dave.
    > --
    > David Meeker
    > http://femm.berlios.de/dmeeker <http://femm.berlios.de/dmeeker>
    >
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- References:
  - RE: [femm] 3D Code (was Re: Linux and 3D)
    - From: Mark Smith <mark.smith@linx.co.uk>

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