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Don't allow king to castle through or out of check #17

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89 changes: 63 additions & 26 deletions Packages/com.emymin.emychess/Runtime/Scripts/Gamerules/DefaultRules.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@


using UdonSharp;
using UnityEngine;
using VRC.SDKBase;
Expand Down Expand Up @@ -77,7 +77,7 @@ private int AppendMove(int index, int x,int y,Vector2[] legalMoves)
int newindex = index;
if (x < 0 || x > 7 || y < 0 || y > 7) { return newindex; }
if (index < legalMoves.Length)
{
{
legalMoves[index] = new Vector2(x, y);
if(index < legalMoves.Length - 1)
{
Expand Down Expand Up @@ -116,13 +116,13 @@ public Vector2[] GetAllPseudoLegalMovesGrid(Piece movedPiece,Piece[] grid,Piece
if (!hasMoved)
{
if (board.GetPiece(x, y + dir* 2) == null) {
index = AppendMove(index, x, y + dir * 2, legalMoves);
index = AppendMove(index, x, y + dir * 2, legalMoves);
}
}
}
Piece pieceCaptureLeft = board.GetGridPiece(x - 1, y + dir,grid);
Piece pieceCaptureRight = board.GetGridPiece(x + 1, y + dir,grid);

if (pieceCaptureLeft != null && pieceCaptureLeft.white!=white)
{
index = AppendMove(index, x - 1, y + dir, legalMoves);
Expand Down Expand Up @@ -153,40 +153,45 @@ public Vector2[] GetAllPseudoLegalMovesGrid(Piece movedPiece,Piece[] grid,Piece
}
else if (type == "king")
{
for(int i = -1; i < 2; i++)
for (int i = -1; i < 2; i++)
{
for(int j = -1; j < 2; j++)
for (int j = -1; j < 2; j++)
{
Piece squarepiece = board.GetGridPiece(x + i, y + j,grid);
if(squarepiece==null||(squarepiece!=null && squarepiece.white != white))
Piece squarepiece = board.GetGridPiece(x + i, y + j, grid);
if (squarepiece == null || (squarepiece != null && squarepiece.white != white))
{
index = AppendMove(index, x + i, y + j, legalMoves);
}
}
}
if (!hasMoved)
{
if (true )//|| !isKingInCheck(movedPiece.GetVec(), board.grid, board, board.PawnThatDidADoublePushLastRound, white)) //TODO very WEIRD stuff happens if I check if the king is in check here (which is necessary because castling is not allowed when the king is in check)
if (!isKingInCheck(movedPiece.GetVec(), grid, board, PawnThatDidADoublePushLastRound, white))
{
foreach(int rookColumn in rookColumns)
foreach (int rookColumn in rookColumns)
{
Piece startRook = board.GetGridPiece(rookColumn, y,grid);
if (startRook!=null && startRook.type == "rook" && !startRook.hasMoved && startRook.white == white)
Piece startRook = board.GetGridPiece(rookColumn, y, grid);
if (startRook != null && startRook.type == "rook" && !startRook.hasMoved && startRook.white == white)
{
bool free = true;
for(int i = Mathf.Min(x, rookColumn) + 1; i < Mathf.Max(x, rookColumn); i++)
for (int i = Mathf.Min(x, rookColumn) + 1; i < Mathf.Max(x, rookColumn); i++)
{
if (board.GetGridPiece(i, y,grid) != null) free = false;
if (board.GetGridPiece(i, y, grid) != null) free = false;
}
if (free)
{
int dir = Mathf.Min(x, rookColumn) == x ? 1 : -1;
index = AppendMove(index, x + dir * 2, y, legalMoves);
Vector2 throughSquare = new Vector2(x + dir, y);
Vector2 endSquare = new Vector2(x + dir * 2, y);
if (!IsSquareUnderAttack(throughSquare, white, grid, board, PawnThatDidADoublePushLastRound) &&
!IsSquareUnderAttack(endSquare, white, grid, board, PawnThatDidADoublePushLastRound))
{
index = AppendMove(index, x + dir * 2, y, legalMoves);
}
}
}
}
}

}
}
else if (type == "rook" || type == "bishop" || type == "queen")
Expand Down Expand Up @@ -303,6 +308,38 @@ public bool isKingInCheck(Vector2 threatenedPos,Piece[] grid,Board board,Piece P
return isKingChecked;
}

/// <summary>
/// Check if a square is under attack
/// </summary>
/// <param name="square"></param>
/// <param name="white"></param>
/// <param name="grid"></param>
/// <param name="board"></param>
/// <param name="PawnThatDidADoublePush"></param>
/// <returns></returns>
private bool IsSquareUnderAttack(Vector2 square, bool white, Piece[] grid, Board board, Piece PawnThatDidADoublePush)
{
foreach (Piece opponentPiece in board.GetAllPieces())
{
if (opponentPiece.white != white)
{
if (isCaptureFeasible(opponentPiece.GetVec(), square, opponentPiece.type))
{
if (board.GetGridPiece(opponentPiece.x, opponentPiece.y, grid) == opponentPiece) // not captured in the test move
{
Vector2[] opponentPseudoLegalMoves = GetAllPseudoLegalMovesGrid(opponentPiece, grid, PawnThatDidADoublePush, board);
foreach (Vector2 opponentPseudoLegalMove in opponentPseudoLegalMoves)
{
if (opponentPseudoLegalMove == legalMovesEndMarker) { break; }
if (opponentPseudoLegalMove == square) { return true; }
}
}
}
}
}
return false;
}

/// <summary>
/// Get all legal moves for a piece
/// </summary>
Expand All @@ -321,35 +358,35 @@ public Vector2[] GetAllLegalMoves(Piece movedPiece, Board board) //TODO needs so
Piece[] testGrid=new Piece[currentGrid.Length];
for(int i=0;i<pseudoLegalMoves.Length;i++)
{

Vector2 pseudoLegalMove = pseudoLegalMoves[i];

if (pseudoLegalMove == legalMovesEndMarker) { break; } else
{

Array.Copy(currentGrid, testGrid, currentGrid.Length);

board.MoveGridPieceVec(piecePos, pseudoLegalMove, testGrid);
Piece PawnThatDidADoublePush=null;
if (movedPiece.type == "pawn" && (Mathf.Abs(movedPiece.x - (int)pseudoLegalMove.x) > 1)){
PawnThatDidADoublePush = movedPiece;
}
Vector2 threatenedPos = movedPiece.type != "king" ? kingPos : pseudoLegalMove;
if (isKingInCheck(threatenedPos, testGrid, board, PawnThatDidADoublePush, movedPiece.white)) { pseudoLegalMoves[i] = legalMovesIgnoreMarker; }

}
}

}
return pseudoLegalMoves;

}

/// <summary>
/// Gets the result of moving a piece to the specified position, as well as performing capture, en passant or castling
/// </summary>
/// <remarks>
/// Will recalculate legal moves, if you already have a list of legal moves
/// Will recalculate legal moves, if you already have a list of legal moves
/// (for example during <see cref="Piece.PieceDropped(int, int)"/>) use <see cref="MoveLegalCheck(Piece, int, int, Board, Vector2[])"/> to pass them
/// </remarks>
/// <param name="movedPiece"></param>
Expand All @@ -373,7 +410,7 @@ public int Move(Piece movedPiece,int x,int y,Board board)
Vector2[] legalMoves = GetAllLegalMoves(movedPiece, board);
return MoveLegalCheck(movedPiece, x, y, board, legalMoves);
}

}

/// <summary>
Expand Down Expand Up @@ -425,15 +462,15 @@ public int MoveLegalCheck(Piece movedPiece,int x,int y, Board board,Vector2[] le
}
movedPiece.hasMoved = true;
movedPiece._SetPosition(x, y);

return result;
}
else
{
movedPiece._SetPosition(movedPiece.x, movedPiece.y);
return 0;
}

}
/// <summary>
/// Resets the board with all pieces in the correct starting positions
Expand Down