David-<div><br></div><div>This is good timing. Hua has been looking into the problem too. We came up with an initial, very limited solution and it will be good to have a more thorough approach. We are looking forward to seeing what you did.</div>
<div><br></div><div>I'm curious, did you create a filter to do this? How did you implement it in VTK....</div><div><br></div><div>Will<br><br><div class="gmail_quote">On Wed, Mar 24, 2010 at 2:39 PM, David Gobbi <span dir="ltr"><<a href="mailto:david.gobbi@gmail.com">david.gobbi@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Hi Will,<br>
<br>
I've finally completed my code for clipping closed polydata shapes and<br>
creating new "cap" polygons so that the result is also a closed<br>
polydata. The solution was more complicated than I originally<br>
thought. After the branch I'll commit it to VTK.<br>
<br>
David<br>
<br>
<br>
On Thu, Feb 18, 2010 at 2:57 PM, Will Schroeder<br>
<div><div></div><div class="h5"><<a href="mailto:will.schroeder@kitware.com">will.schroeder@kitware.com</a>> wrote:<br>
> Awesome David, simply great. You are ahead of us for now, but we will<br>
> definitely need something like this soon. Can we ping you when we are ready?<br>
><br>
> On Thu, Feb 18, 2010 at 3:04 PM, David Gobbi <<a href="mailto:david.gobbi@gmail.com">david.gobbi@gmail.com</a>> wrote:<br>
>><br>
>> Hi Will,<br>
>><br>
>> Have you and Hua done the "Clip" part of the cell implementation yet?<br>
>> If not, I might have some code that will help. I've been working on a<br>
>> class for clipping of watertight polydata in VTK. It does the capping<br>
>> of the open end after a clip:<br>
>><br>
>> - contouring the polydata at the clip plane to get the clip-edges of<br>
>> the clipped polygons<br>
>> - joining the new edge line segments into a one or more cap polygons<br>
>> - identifying complex polygons, i.e. polygons with holes<br>
>> - triangulating the polygons (*partly done*)<br>
>><br>
>> The "triangulating" part is the only part that I haven't finished<br>
>> (that's why I asked about Delaunay earlier). I'm using ear-cut<br>
>> triangulation, which only works for simple polygons, but other than<br>
>> that everything is done.<br>
>><br>
>> David<br>
>><br>
>><br>
>> On Thu, Feb 18, 2010 at 9:38 AM, Will Schroeder<br>
>> <<a href="mailto:will.schroeder@kitware.com">will.schroeder@kitware.com</a>> wrote:<br>
>> > Hua and I have made progress on adding a vtkPolyhedron cell to VTK. We<br>
>> > have<br>
>> > a wiki page describing the tasks (which will take some time<br>
>> > to implement depending on our funding and<br>
>> > schedule <a href="http://www.vtk.org/Wiki/VTK/Polyhedron_Support" target="_blank">http://www.vtk.org/Wiki/VTK/Polyhedron_Support</a>). We are using<br>
>> > the<br>
>> > interpolation method of mean value coordinates which Hua has already<br>
>> > implemented, thus far it is a super algorithm. Comments are welcome.<br>
>> > We are now starting the integration into vtkUnstructuredGrid. If you are<br>
>> > interested let me know and at the appropriate point we can make our git<br>
>> > repository available.<br>
>> ><br>
>> ><br>
>> > On Thu, Jan 21, 2010 at 6:53 AM, Will Schroeder<br>
>> > <<a href="mailto:will.schroeder@kitware.com">will.schroeder@kitware.com</a>><br>
>> > wrote:<br>
>> >><br>
>> >> FYI-<br>
>> >><br>
>> >> Hua Yang and I are adding a new cell type to VTK: the polyhedral cell.<br>
>> >> This is mainly to support our CFD friends who like to compute flow<br>
>> >> solutions<br>
>> >> using flux approaches (balance mass and energy in and out of a region).<br>
>> >><br>
>> >> One of the key questions is how to interpolate across the interior of<br>
>> >> such<br>
>> >> a cell. In the past I have seen two typical approaches 1) tessellate<br>
>> >> the<br>
>> >> polyhedron into tetrahedra, and then use the tetrahedra to interpolate;<br>
>> >> and<br>
>> >> 2) use a 1/r**2 (or similar weighting function) to interpolate from the<br>
>> >> cell<br>
>> >> nodes to an interior point in the polyhedron. Both approaches have<br>
>> >> problems<br>
>> >> with continuity, etc.<br>
>> >><br>
>> >> We are also researching other approaches. However in the interest of<br>
>> >> completeness, if anybody has suggestions for alternatives we'd love to<br>
>> >> hear<br>
>> >> about them.<br>
>> >><br>
>> >> Will<br>
>> ><br>
>> ><br>
>> ><br>
>> > --<br>
>> > William J. Schroeder, PhD<br>
>> > Kitware, Inc.<br>
>> > 28 Corporate Drive<br>
>> > Clifton Park, NY 12065<br>
>> > <a href="mailto:will.schroeder@kitware.com">will.schroeder@kitware.com</a><br>
>> > <a href="http://www.kitware.com" target="_blank">http://www.kitware.com</a><br>
>> > (518) 881-4902<br>
>> ><br>
>> > _______________________________________________<br>
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>><br>
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><br>
><br>
><br>
> --<br>
> William J. Schroeder, PhD<br>
> Kitware, Inc.<br>
> 28 Corporate Drive<br>
> Clifton Park, NY 12065<br>
> <a href="mailto:will.schroeder@kitware.com">will.schroeder@kitware.com</a><br>
> <a href="http://www.kitware.com" target="_blank">http://www.kitware.com</a><br>
> (518) 881-4902<br>
><br>
</div></div></blockquote></div><br><br clear="all"><br>-- <br>William J. Schroeder, PhD<br>Kitware, Inc.<br>28 Corporate Drive<br>Clifton Park, NY 12065<br><a href="mailto:will.schroeder@kitware.com">will.schroeder@kitware.com</a><br>
<a href="http://www.kitware.com">http://www.kitware.com</a><br>(518) 881-4902<br>
</div>