[vtkusers] Bug in vtkQuadraticTetra.cxx?

[Rainer Sabelka]

Hi,

I just looked into the file vtkQuadraticTetra.cxx and wonder if the following 
lines I found there can be correct

//clip each of the four vertices; the remaining octahedron is
//divided into two tetrahedron.
static int Tetras[6][4] = { {0,4,6,7}, {4,1,5,8}, {6,5,2,9},
                            {7,8,9,3}, {6,4,5,8}, {6,9,7,8} };

>From my point of view you need at least four tetras to build an octahedron.
These are the three possible splitting matrices I use in a FEM program:

{{0,4,6,7},{1,5,4,8},{2,6,5,9},{7,8,9,3},{7,8,6,9},{6,8,5,9},{7,6,8,4},{6,5,8,4}},
{{0,4,6,7},{1,5,4,8},{2,6,5,9},{7,8,9,3},{7,5,6,9},{7,5,9,8},{7,5,8,4},{7,5,4,6}},
{{0,4,6,7},{1,5,4,8},{2,6,5,9},{7,8,9,3},{9,4,6,5},{9,4,5,8},{9,4,8,7},{9,4,7,6}}

I hope the node numbering scheme I use here is the same as in VTK.

Cheers,
Rainer