[Bf-committers] Adding support for tetrahedron and hexahedron elements

[Iman Brasseur]

I like the idea of staying out of the c-code for simplicity and also not
requiring a modified version of Blender to use it.

With existing open source meshing tools I had trouble creating organic
shapes ( I'd be interested to hear if I missed something here, i'm not very
familiar with these tools )

With Tetgen I had trouble getting nice low element-count meshes for
real-time simulation in an efficient manner. But maybe a script that
integrates Tetgen with blender will make this easier, because much quicker
iterations can be made, adjusting the surface mesh in blender and seeing
the result right away. I think i'll give that a try first. Thanks for all
your comments!

Iman





On Fri, Nov 8, 2013 at 6:22 AM, George Robert Anderson <
george.anderson at stanford.edu> wrote:

> I'd agree with that assessment. I've never encountered much, if any, need
> for manually editing an FE mesh, and Blender users are even less likely to
> need that. I would encourage Iman to try implementing an importer and
> exporter as a Python plugin. I think you can do everything short of
> point-and-click extrusion with some relatively simple scripts (maybe a few
> 100 lines). Remember that with Python you have access to the low-level mesh
> operations via bmesh. Once you scope it out there and demonstrate the use
> cases, you'll have a better shot at getting support from the developers.
>
> George
>
> четверг, 7 ноября 2013 г. пользователь Brecht Van Lommel писал:
>
> > I'm not so convinced about adding editing support for such a data
> > structure to Blender now. I can see the point of simulation tools
> > generating or storing such volumetric elements, but going all the way
> > to edit mode and BMesh seems like it would add a ton complexity to the
> > mesh system, for uses cases that Blender is not focused on (CAD).
> >
> > A Volume primitive in addition to a Mesh does makes sense to be, but
> > something based on regular grids is more standard for Animation and
> > VFX. Tetrahedral meshes might be used in some simulations there, but a
> > manual editing system for them I haven't heard of, they tend to be
> > automatically generated from a surface mesh. Manually editing and
> > doing topological operations like BMesh seems too specialized for
> > Blender to support.
> >
> > Brecht.
> >
> > On Thu, Nov 7, 2013 at 10:51 PM, Iman Brasseur <iman.brasseur at gmail.com
> <javascript:;>>
> > wrote:
> > > Hi everybody,
> > >
> > > I'm looking into adding support for volumetric elements in Blender. The
> > > idea is to be able to create and export meshes for finite elements that
> > > contain tetrahedral and hexahedral elements. To create such meshes one
> > > could start for example with a single tetrahedron. Then when selecting
> a
> > > triangular face, instead of extruding the triangle as a wedge-shaped
> new
> > > surface, it would create a new tetrahedral element that shares 3
> vertices
> > > with the original tetrahedron.
> > >
> > > Going through the source code, I thought I should start with
> > bmesh_class.h
> > > and add (next to the BMVert, BMEdge, BMFace) a new element type BMVol
> to
> > > add the new volumetric element there. Does that seem like the right way
> > to
> > > start? Any quick hints to pieces of code I should look at would be
> > greatly
> > > appreciated!
> > >
> > > Thanks!
> > >
> > > Iman
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