8 18 12 GtsSurface GtsFace GtsEdge GtsVertex
0 1 2
0 1 0
0 0 1
1 1 0
1 0 1
1 0 0
0 0 0
1 1 2
1 2
3 2
1 3
4 5
6 5
6 4
7 2
4 2
7 4
7 6
8 5
4 8
7 5
3 5
7 3
8 2
3 8
1 8
1 2 3
4 5 6
7 8 9
9 6 10
11 4 12
5 13 10
13 14 15
8 16 12
2 7 15
17 18 3
14 11 17
16 1 18