// prismcone.fe

// Surface Evolver datafile for a cone over triangular prism frame.  
// The height is carefully chosen so that the films meet at 120 degrees.
// This is an equilibrium soap film, but not absolutely area minimizing.

vertices
1   1 1 1  fixed
2  -1 -1 1 fixed
3   1 -1 -1  fixed
4  1/3 5/3 1/3 fixed
5  -5/3 -1/3 1/3 fixed
6  1/3 -1/3 -5/3 fixed
7  0 0 0

edges
1   1 2 fixed
2   2 3 fixed
3   3 1 fixed
4   4 5 fixed
5   5 6 fixed
6   6 4 fixed
7   1 7
8   2 7
9   3 7
10  4 7
11  5 7
12  6 7
13  1 4 fixed
14  2 5 fixed
15  3 6 fixed

faces
1  1 8 -7
2  2 9 -8
3  3 7 -9
4  4 11 -10
5  5 12 -11
6  6 10 -12
7  7 -10 -13
8  8 -11 -14
9  9 -12 -15

read

// Command to evolve into absolutely area minimizing film
gogo := { o;  // pop central vertex
          g 20;
          t .31;  // get rid of some edges to make triangulation more symmetric
          r; g 10; u; g 10;
          hessian_normal; hessian; hessian;
          r; g 10; u; g 10; u; g 10;
          hessian; hessian;
         }