[0] = [ 1 0.5 0 0 ]
[1] = [ 1 -1 0 0 ]
[2] = [ 0 0 1 0 ]
[3] = [ 0 0 0 1 ]
[3] = [ 0 0 0 -1 ]
[6] = [ 0 0 1 -1 ]
[4] = [ 1.5 -0.5 0 0 ]
[4] = [ 1.75 0.25 0 0 ]