🕸Fergus Duniho wrote on Tue, Aug 22, 2017 03:44 PM UTC:
For any space a Sissa can reach, there are four possible paths to it if it is on the same rank or file, and there are two possible paths to it if it lies in a hippogonal direction. For each possible path, there is only one possible turning point. So here are the steps to follow in calculating the legality of a Sissa move.
Check whether the move is to a space that could be reached by a Rook or Nightrider move. If it cannot be, the move is illegal.
If it is to the same rank, find the (up to) four spaces that are the same distance away from origin or dest along the file.
If it is to the same file, find the (up to) four spaces that are the same distance away from origin or dest along the rank.
If it lies in a hippogonal direction, find its shorter distance away, and find the (up to) two spaces that distance away along a rank or file and along a diagonal that each increase in the direction of the longer distance away.
For each of the possible turning points, check whether the piece could make a Bishop or Rook move to it and then reach the destination by the other kind of move.
For any space a Sissa can reach, there are four possible paths to it if it is on the same rank or file, and there are two possible paths to it if it lies in a hippogonal direction. For each possible path, there is only one possible turning point. So here are the steps to follow in calculating the legality of a Sissa move.