0 0 z a
0 0 z+1/2 a
1/3 2/3 z b
2/3 1/3 z+1/2 b
1/3 2/3 z+1/2 b
2/3 1/3 z b
x 0 z c
0 x z c
-x -x z c
-x 0 z+1/2 c
0 -x z+1/2 c
x x z+1/2 c
x y z d
-y x-y z d
-x+y -x z d
-x -y z+1/2 d
y -x+y z+1/2 d
x-y x z+1/2 d
-y -x z+1/2 d
-x+y y z+1/2 d
x x-y z+1/2 d
y x z d
x-y -y z d
-x -x+y z d