How do I get started?

[sombor-shuffle]

I'd like to use Chessground + scalachess with the intention of validating moves made on a board.

I can't find a documentation on how to use scalachess. I cloned the project, installed sbt, and ran compile (as per the README). But from here on out I'm completely in the dark.

How do I use scalachess to validate a chess position?

I realize that this probably isn't an appropriate issue, and would appreciate any pointer in a more sensible direction.

[lenguyenthanh]

Hey @sombor-shuffle,
unfortunately, we don't have a documentation about scalachess. Can you please tell us about your usecase with scalachess, so we can help?

In the mean time, please refer to tests, lila/lila-ws for some references. I also have some standalone examples here:

• https://github.com/lenguyenthanh/scalachess-tests
• https://github.com/lenguyenthanh/chess-position-generator
• https://github.com/lenguyenthanh/scala-examples

Please take a look!

Also you can join our discord and we ask there: https://discord.gg/lichess

[sombor-shuffle]

Hello, @lenguyenthanh!

Apologies for not writting back faster. Thank you for helping me out!

I wanted to highlight all legal moves (with the rules of antichess) for a selected piece, as seen below:

My solution ended up using chessops, instead (roughly paraphrased from a component in my Next.js project):

import { Chessground } from 'chessground';

import { chessgroundDests } from 'chessops/compat';
import { Antichess } from "chessops/variant";
import { parseSquare } from 'chessops/util';

import "chessground.base.css";
import "chessground.brown.css";
import "chessground.cburnett.css";

// Create a container for chessground.
const container = document.createElement("div");
document.body.appendChild(container);

// Give it some size. Otherwise it won't be visible.
container.style.width = "500px";
container.style.height = "500px";

// Handles logic and initializes to starting position.
const ops = Antichess.default();

// Chessground config file:
const config = { 
  movable: {
    color: "white",

    // Only the moves given below are allowed to be made.
    free: false,

    // chessops has a built-in function that can be assigned to dests.
    // This will highlight all legal moves.
    dests: chessgroundDests(ops), 
    
  }
}

const cg = Chessground(container, config);

// Can't be set in config as it references cg (which won't exist yet)
cg.set({
  movable: { events: { after: handleMove(cg, ops) } }
});


// Called when a move is made.
function handleMove(cg, ops) { 
  
  return (orig, dest) => {
    
    // Converts e1 - h8 to 0 - 63, for chessops.
    const from = parseSquare(orig), to = parseSquare(dest);

    if(from && to) {

      const move = { from, to }

      // Updates the internal board of chessops.
      ops.play(move);

      // Updates Chessground with new active color
      // and new legal moves.
      cg.set({
        turnColor: ops.turn,
        movable: {
          color: ops.turn,
          dests: chessgroundDests(ops)
        }
      });

    }
  }
}

Thank you for linking me these resources. I'm very interested to learn more about how Lichess works and will dive into them. Appreciate it king!

[lenguyenthanh]

that's great too hear! good luck on your adventure!