i am writing an graphical user interface for chess using OpenGl. I
need to also validate the moves of the players as the interface should
be usable across a network.

The problem arises when i try to identify the cases when a checkmate
or a stalemate position. i have no better idea than computing all
possible next moves and finding that they are invalid. This is a too
big a task to perform after every move.

on the other hand giving the user an option to claim checkmate or
draw seems too naive. Is there a better algorithm to find this out.

thanks for anything from pointers to code ( in C or C++)

abi wrote:

i am writing an graphical user interface for chess using OpenGl. I
need to also validate the moves of the players as the interface should
be usable across a network.

The problem arises when i try to identify the cases when a checkmate
or a stalemate position. i have no better idea than computing all
possible next moves and finding that they are invalid.

Yes, there is probably no other efficient and easy to implement way.

This is a too
big a task to perform after every move.

Why? It should take only some microseconds for each move, probably much
less than needed to redraw the board, or whatever else you do in you GUI.
But it needs almost a chess-engine, to verify - sure. You'll need a move-
generator, an "Incheck" routine, and a one ply search. But it won't take
long.

Regards,
Dieter