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