Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

⚖️ Incremental eval - bishop pair #1360

Draft
wants to merge 2 commits into
base: main
Choose a base branch
from
Draft

⚖️ Incremental eval - bishop pair #1360

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
f435c86
Add simplies incrmeental bishop pair implementation
eduherminio Jan 11, 2025
bc9f103
Merge branch 'main' into eval/incremental-bishop-pair
eduherminio Jan 14, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
51 changes: 40 additions & 11 deletions src/Lynx/Model/Position.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -129,6 +129,18 @@ public GameState MakeMove(Move move)
if (promotedPiece != default)
{
newPiece = promotedPiece;

//if (_isIncrementalEval && PieceBitBoards[(int)Piece.B + offset] != 0)
//{
// if (promotedPiece == (int)Piece.B)
// {
// _incrementalEvalAccumulator += BishopPairBonus;
// }
// else if (promotedPiece == (int)Piece.b)
// {
// _incrementalEvalAccumulator -= BishopPairBonus;
// }
//}
}

PieceBitBoards[piece].PopBit(sourceSquare);
Expand Down Expand Up @@ -184,6 +196,23 @@ public GameState MakeMove(Move move)

_incrementalEvalAccumulator -= PSQT(0, opposideSideBucket, capturedPiece, capturedSquare);
_incrementalEvalAccumulator -= PSQT(1, sameSideBucket, capturedPiece, capturedSquare);

// Remove bishop bonus when a bishop is captured and the other bishop is still on the board
// We'll ignote bishop promotions for now
if (capturedPiece == (int)Piece.B)
{
if (PieceBitBoards[capturedPiece] != 0)
{
_incrementalEvalAccumulator -= BishopPairBonus;
}
}
else if (capturedPiece == (int)Piece.b)
{
if (PieceBitBoards[capturedPiece] != 0)
{
_incrementalEvalAccumulator += BishopPairBonus;
}
}
}

break;
Expand Down Expand Up @@ -663,6 +692,17 @@ public bool WasProduceByAValidMove()
+ PSQT(0, blackBucket, (int)Piece.k, blackKing)
+ PSQT(1, whiteBucket, (int)Piece.k, blackKing);

// Bishop pair bonus
if (PieceBitBoards[(int)Piece.B].CountBits() >= 2)
{
_incrementalEvalAccumulator += BishopPairBonus;
}

if (PieceBitBoards[(int)Piece.b].CountBits() >= 2)
{
_incrementalEvalAccumulator -= BishopPairBonus;
}

packedScore += _incrementalEvalAccumulator;
_isIncrementalEval = true;
}
Expand All @@ -671,17 +711,6 @@ public bool WasProduceByAValidMove()
KingAdditionalEvaluation(whiteKing, (int)Side.White, blackPawnAttacks)
- KingAdditionalEvaluation(blackKing, (int)Side.Black, whitePawnAttacks);

// Bishop pair bonus
if (PieceBitBoards[(int)Piece.B].CountBits() >= 2)
{
packedScore += BishopPairBonus;
}

if (PieceBitBoards[(int)Piece.b].CountBits() >= 2)
{
packedScore -= BishopPairBonus;
}

// Pieces attacked by pawns bonus
packedScore += PieceAttackedByPawnPenalty
* ((blackPawnAttacks & OccupancyBitBoards[(int)Side.White] /* & (~whitePawns) */).CountBits()
Expand Down
Loading