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evaluator.cc
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evaluator.cc
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#include <numeric>
#include "evaluator.h"
/**
* Approximate material values.
*/
static CentipawnScore pawnPoints = 100, knightPoints = 320, bishopPoints = 330, rookPoints = 510, queenPoints = 880;
CentipawnScore Evaluator::getPieceValue(Piece piece) {
switch(piece) {
case Pawn:
return pawnPoints;
case Knight:
return knightPoints;
case Bishop:
return bishopPoints;
case Rook:
return rookPoints;
case Queen:
return queenPoints;
default:
assert(false);
}
return 0;
}
/**
* Just counts material
*/
CentipawnScore EvalLevelThree::staticEvaluate(const Board& board) {
CentipawnScore eval = 0;
for (int i = 0; i < NumSquares; ++i) {
switch(board.getPieceAt(getSquareFromIndex(i))) {
case Empty:
break;
case WhitePawn:
eval += pawnPoints;
break;
case BlackPawn:
eval -= pawnPoints;
break;
case WhiteKnight:
eval += knightPoints;
break;
case BlackKnight:
eval -= knightPoints;
break;
case WhiteBishop:
eval += bishopPoints;
break;
case BlackBishop:
eval -= bishopPoints;
break;
case WhiteRook:
eval += rookPoints;
break;
case BlackRook:
eval -= rookPoints;
break;
case WhiteQueen:
eval += queenPoints;
break;
case BlackQueen:
eval -= queenPoints;
break;
default:
break;
}
}
return board.getTurn() == White ? eval : -eval;
}
CentipawnScore EvalLevelFour::staticEvaluate(const Board& board) {
if(board.isBoardMaterialDraw()) {
return 0;
}
// Give bonuses to positionally good things (like rooks on open files)
// and penalize bad things (like isolated pawns).
CentipawnScore isolatedPawns = IsolatedPawnBonus * (board.getNumberOfIsolatedPawns(White) - board.getNumberOfIsolatedPawns(Black));
CentipawnScore passedPawns = PassedPawnBouns * (board.getNumberOfPassedPawns(White) - board.getNumberOfPassedPawns(Black));
CentipawnScore bishopPair = 0;
if(board.getSidePieceCount(White, Bishop) >= 2) {
bishopPair += BishopPairBonus;
}
if(board.getSidePieceCount(Black, Bishop) >= 2) {
bishopPair -= BishopPairBonus;
}
CentipawnScore rookBonus = RookOpenFileBonus * (board.getNumberOfPiecesOnOpenFile(White, Rook) - board.getNumberOfPiecesOnOpenFile(Black, Rook));
rookBonus += RookSemiOpenFileBonus * (board.getNumberOfPiecesOnSemiOpenFile(White, Rook) - board.getNumberOfPiecesOnSemiOpenFile(Black, Rook));
CentipawnScore queenBonus = QueenOpenFileBonus * (board.getNumberOfPiecesOnOpenFile(White, Queen) - board.getNumberOfPiecesOnOpenFile(Black, Queen));
queenBonus += QueenSemiOpenFileBonus * (board.getNumberOfPiecesOnSemiOpenFile(White, Queen) - board.getNumberOfPiecesOnSemiOpenFile(Black, Queen));
CentipawnScore subtotal = board.getCurrentPsqt() + isolatedPawns + bishopPair + passedPawns + rookBonus + queenBonus;
return TempoBonus + (board.getTurn() == White ? subtotal : -subtotal);
}