gmvinput ascii
nodes 20
  0  50 50 0  0  0 50 50  25 25 25  25 75 -25 25  25 99 -49 5  25
  0   0  0 0 50 50 50 50 -25 25 75  25 25  25 75  75 75  75 5 150
  50 50  0 0 50  0  0 50  25 75 25 -25 25  25 99 -49 25  25 5  25
cells 1
vface3d  4  1 2 3 4
vfaces  4
 4          1   0       1           1             5    1   2   8
 3          1   0       1           1             8    5  10
 3          1   0       1           1             2    8  10
 3          1   0       1           1             1    2  10
material 1 0
mat1
1 
endgmv
