Reverse Explode

From a 1-faced line, the ends step forward, all face away from the original center of the line, and adjust to a new line.

\syhlines{b4n,g4n,b1n,g1n} \sxvlines{g1e,b1e,g2e,b2e}
4 2 4 2 1 3 1 3 1 3 1 3 2 4 2 4
before Reverse Explode after