Chess960 castling is not handled

[undera]

Hi, I'm applying this nice viewer to Chess960 PGNs. It works well except castling moves, which breaks it with message No legal move: O-O.

Here is PGN:

[Site "checkmate"]
[Round "191"]
[White "Lisa"]
[Black "Stockfish"]
[Result "0-1"]
[FEN "nrnkrqbb/pppppppp/8/8/8/8/PPPPPPPP/NRNKRQBB w KQkq - 0 1"]
[Variant "Chess960"]

1. e4 {0.00} f5 {0.00} 2. Qe2 {0.00} fxe4 {0.00} 3. Qf1 {0.00} g6 {0.00} 4.
Qe2 {0.00} Nab6 {0.00} 5. Qf1 {0.00} Nc4 {0.00} 6. Qe2 {0.00} Nxb2+ {0.00} 7.
Rxb2 {0.00} Bxb2 {0.00} 8. Qf1 {0.00} Bxa1 {0.00} 9. Qe2 {0.00} Nd6 {0.00} 10.
Qf1 {0.00} Bc4 {0.00} 11. Qe2 {0.00} Bxe2+ {0.00} 12. Kxe2 {0.00} Qf5 {0.00}
13. Kd1 {0.00} Bd4 {0.00} 14. c3 {0.00} Bxf2 {0.00} 15. Re2 {0.00} Bxg1 {0.00}
16. d3 {0.00} exd3 {0.00} 17. Ke1 {0.00} dxe2 {0.00} 18. Kxe2 {0.00}
Qc2+ {0.00} 19. Ke1 {0.00} O-O {0.00} 20. c4 {0.00} Bf2+ {0.00} 21. Kf1 {0.00}
Qd1# {0.00} 0-1

Here is my JS code.

        var match = /^\[FEN "([^"]+)"]/m.exec(pgn);
        var cfg = {
            position: match[1],
            pgn: pgn,
            locale: 'en',
            pieceStyle: 'wikipedia',
            timerTime: 200,
            movesHeight: '200px',
        };
        console.log(cfg);
        var board = pgnView('board', cfg);

[mliebelt]

Nice idea! I never had thought that this could possibly work. The reason is, that the library used for playing and controlling chess is (as I think) not able to check Chess960. I will check that, and if it is possible will add the option to use the PgnViewerJS for it.

[mliebelt]

See https://github.com/jhlywa/chess.js/issues/122 for an issue in the library I am using. There is the mentioning of a branch that includes a (partial) implementation, I will give it a try. But this "we need X-FEN instead of FEN" frightens me, that does not sound easy ...

[mliebelt]

Found the castling rules here, they seem to be simple. Don't know how easy it would be to implement them generally in chess.js, however.

[mliebelt]

I have just added (in a branch) the version of sesse instead of the original one, and added an example to show the effect.

You have to do the following:

• Clone the repository: clone https://github.com/mliebelt/PgnViewerJS.git.
• Go into the directory of the repository: cd PgnViewerJS
• Checkout branch ticket-121: git checkout ticket-121
• Run npm install
• Run grunt dev
• Run npm install -g http-server (to have a local web server, necessary to run the examples).
• Run http-server --cors, this will display an URL (with port) that servers that directory. This is named <URL> in the following.
• Open the browser at <URL>/examples/tickets/ticket121.html
• Play through the game (including castling).

I have to check the changes of course if it is possible to include them into main line of PgnViewerJS. If there is not too much risk, I will do that, and create a new release for easier user of PgnViewerJS (with support for Chess960).

[mliebelt]

Playing (in edit mode), I have seen that I have no support for castling that works well. That means, the king is set correct, but the rook not. And I have the problem that castling is sometimes not even possible. So in your game (with Rb1 and Kd1), moving the king to c1 is ambiguous: it could be castling, and it could be a normal move. So playing the moves with pgnView would be ok, but not using pgnEdit to create a game for Chess960.

Of course this is only a first draft. There should be an attribute for it (variant: "chess960", default: "chess"), the read of the TAG [Variant "Chess960"], but this is all trivial in comparison to the change of castling rules.

[undera]

Thanks for all your research. Currently, I'm only using PGNView and castling in PGN is unambiguous with special O-O-kind declarations.

[mliebelt]

Are you able to build it for yourself?

[undera]

I'm not big JS guy. When I'm using it, I generated the config via web UI and downloaded the release and use dist directory. Sorry, I don't have npm or grunt on my machine.

[undera]

Well, I made it to build dist somehow, played ticket121.html and it worked as expected.

[mliebelt]

Great! So you have at least a version that works for you, and I have some more time to do some checks and to ensure that nothing else will break then.

[undera]

Yes, thank you very much for your help.

[intothephone]

I have just added (in a branch) the version of sesse instead of the original one, and added an example to show the effect.

You have to do the following:

• Clone the repository: clone https://github.com/mliebelt/PgnViewerJS.git.
• Go into the directory of the repository: cd PgnViewerJS
• Checkout branch ticket-121: git checkout ticket-121
• Run npm install
• Run grunt dev
• Run npm install -g http-server (to have a local web server, necessary to run the examples).
• Run http-server --cors, this will display an URL (with port) that servers that directory. This is named <URL> in the following.
• Open the browser at <URL>/examples/tickets/ticket121.html
• Play through the game (including castling).

I have to check the changes of course if it is possible to include them into main line of PgnViewerJS. If there is not too much risk, I will do that, and create a new release for easier user of PgnViewerJS (with support for Chess960).

Can't find the branch ticket-121

I have just added (in a branch) the version of sesse instead of the original one, and added an example to show the effect.

You have to do the following:

• Clone the repository: clone https://github.com/mliebelt/PgnViewerJS.git.
• Go into the directory of the repository: cd PgnViewerJS
• Checkout branch ticket-121: git checkout ticket-121
• Run npm install
• Run grunt dev
• Run npm install -g http-server (to have a local web server, necessary to run the examples).
• Run http-server --cors, this will display an URL (with port) that servers that directory. This is named <URL> in the following.
• Open the browser at <URL>/examples/tickets/ticket121.html
• Play through the game (including castling).

I have to check the changes of course if it is possible to include them into main line of PgnViewerJS. If there is not too much risk, I will do that, and create a new release for easier user of PgnViewerJS (with support for Chess960).

@mliebelt Thank you, also need this feature, but I can't find branch ticket-121, had it been merged into the main branch?

[mliebelt]

@intothephone Sorry for the inconvenience, but I did a trial ~4.5 years ago, that never made it into any release. The commit is there, you can see what I tried here. See the commit on Github. Hopefully that is sufficient to understand the idea. As you may see, the ticket is open ...

[intothephone]

Got it, thank you very much! Your project is great!