my @points = ( [0,0], [2, 0],  [0, 2], [2, 2] );

##</code><code>##

[
  [1, 0, 1, 0, 1], # X=1 for points 0, 1
  [0, 1, 1, 0, 2], # Y=1 for points 0, 2
  [0, 1, 1, 1, 3], # Y=1 for points 1, 3
  [1, 1, 2, 0, 3], # X+Y=2 for points 0, 3
  [1, 0, 1, 2, 3], # X=1 for points 2, 3
]

##</code><code>##

[
  [3, 1, 0],   # Edge from (1,1) to (1,1)
  [1, -1, 1],
  [4, -1, 1],
  [2, 0, -1],
  [0, 0, -1]
]

##</code><code>##

[
  [1, 1],
  [1, 1]
]