If on a gris, each node should keep track of its connections: top, top left/right, right/left, bottom and bottom left/right. When trying to connect diagonally, check 1 node horizontal if it has a connection that would block.
For a grid:
[0][0] [0][1]
[1][0] [1][1]
[0][0] would check [0][1] if bottom left is true.
The distance check is with world location or index within the array?