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Re: [femlisp-user] Constructing 2D domain

From: Sebastian Sturm
Subject: Re: [femlisp-user] Constructing 2D domain
Date: Mon, 1 Nov 2010 12:31:54 +0100

You can look at the tests in "src/mesh/triangulate.lisp" where a circle
domain is defined only by its boundary and then triangulated using

If you want this, then you should specify the boundaries (line segments)
for each region as linking the corner points (this is a 1d "skeleton"),
and use these to define "region blobs" with those boundaries.  Those can
be triangulated using Triangle.

Thank you, that helped alot. The basic shape of (one part of the) domain looks fine now (shaped like the capital letter 'H'), however I'm still at a loss how to cut out arbitrarily shaped subregions. The examples (like n-cube-with-cubic-hole) all seem to require that the hole's boundary is obtained from an explicit deformation of the outer boundary. Is there some function that allows me to take a generic domain and cut out some others (akin to the boolean functions found in Inkscape or Illustrator)? I guess that something of this kind has been used for the absorption application http://www.femlisp.org/absorption.html?

On a side note, I had problems installing OpenDX using macports and
since it seems to be abandonware anyway, I'd rather do without it.

OK, I have not used a Mac with Femlisp graphics in the last two years.
But I have one with Mac OS 10.6 available.  I'll try it next week.

For now I'm using cl-cairo and Mathematica to visualize meshes and
corresponding solutions, but as there seems to be a VTK version in the
works, I'd like to know if there is already some preliminary version
up for testing?

You should be able to write data out in VTK file format using

(plot .... :program :vtk)
[This has as default output a file "images/output.vtk".  The name is
also printed for convenience.]

that sounds very promising, but somehow it doesn't work with my installation (using quicklisp-installed femlisp). The REPL flatly states "<Plotting suppressed>"; also, I didn't find "vtk" in the src directory, whereas "dx" gave me a lot of grep hits. Am I missing some additional package here?

Best regards,

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