[vtkusers] convert a grid of tetrahedra to a grid of triangles

[Stephen Langer]

I was confused.  It's the vtkCutter that I was using to draw on the clipping plane that's introducing the extra edges.  I think I can avoid using it in this case.
Thanks.

 -- Steve

On Jun 22, 2012, at 12:41 PM, Nam-Van TRAN wrote:

> Hi,
> 
> You should use algorithm vtkTableBasedClipDataSet to clip grid in your case 
> 
> Hope that can help you
> 
> 2012/6/19 Stephen Langer <stephen.langer at nist.gov>
> Hi --
> 
> Is there an easy way in vtk to convert a vtkUnstructuredGrid that contains only tetrahedral cells into a vtkUnstructuredGrid that contains only triangular cells, where the triangles are the faces of the original tetrahedra?
> 
> The reason that I want to do this is that I'm displaying a tetrahedral mesh as a wireframe, and I'm clipping the mesh with vtkClipDataSet.  Because the clipping creates only tetrahedral cells, it adds new edges and faces within the clipped tetrahedra.  I only want to display the original edges, so I use vtkExtractEdges to convert the grid to a grid of lines, and clip the lines instead.  That works well, but then I want to add new lines on the clipping plane, showing where the original faces
> intersect the plane.  Using vtkCutter on the original grid creates only triangular cells, even where the intersection of a tetrahedron with the plane is quadrilateral.  I want to display the quadrilateral as a wireframe quadrilateral, not as two triangles.  Is that possible?  If I had a grid that only contained the faces of the original tetrahedra, then cutting that grid would produce the lines that I want.
> 
> Thanks,
>      Steve
> 
> --
> -- stephen.langer at nist.gov                    Tel: (301) 975-5423 --
> -- http://math.nist.gov/~SLanger/             Fax: (301) 975-3553 --
> -- NIST, 100 Bureau Drive, Stop 8910, Gaithersburg, Md 20899-8910 --
> 
> "I've just had the best idea. I'm going to make hats out of Nutella."
>                                       -- Nadia Langer, 10 Mar 2012
> (Not intended as a product endorsement or statement of suitability.)
> 
> 
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> -- 
> Nam-Van TRAN
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--
-- stephen.langer at nist.gov                    Tel: (301) 975-5423 --
-- http://math.nist.gov/~SLanger/             Fax: (301) 975-3553 --
-- NIST, 100 Bureau Drive, Stop 8910, Gaithersburg, Md 20899-8910 --

"I've just had the best idea. I'm going to make hats out of Nutella."
                                       -- Nadia Langer, 10 Mar 2012 
(Not intended as a product endorsement or statement of suitability.)