use std::f32::INFINITY; use crate::{board::{piece::Piece, color::Color, CastlingSide}, bitboard::{Bitboard, BitboardFns}, square::Square}; use super::Grossmeister; /// Score in pawns (not centipawns) pub type Score = f32; const PAWN_BONUS: [Score; 64] = [ // A B C D E F G H 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.50, 0.50, 0.50, 0.50, 0.50, 0.50, 0.50, 0.50, 0.10, 0.10, 0.20, 0.30, 0.30, 0.20, 0.10, 0.10, 0.05, 0.05, 0.10, 0.25, 0.25, 0.10, 0.05, 0.05, 0.00, 0.00, 0.00, 0.20, 0.20, 0.00, 0.00, 0.00, 0.05, -0.05, -0.10, 0.00, 0.00, -0.10, -0.05, 0.05, 0.05, 0.10, 0.10, -0.20, -0.20, 0.10, 0.10, 0.05, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00 ]; const PAWN_BONUS_PASSER_ENDGAME: [Score; 64] = [ // A B C D E F G H 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 2.00, 1.00, 1.00, 1.00, 1.00, 1.00, 1.00, 1.00, 1.00, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.70, 0.50, 0.50, 0.50, 0.50, 0.50, 0.50, 0.50, 0.50, 0.30, 0.30, 0.30, 0.30, 0.30, 0.30, 0.30, 0.30, 0.10, 0.10, 0.10, 0.10, 0.10, 0.10, 0.10, 0.10, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, ]; const KNIGHT_BONUS: [Score; 64] = [ // A B C D E F G H -0.50, -0.40, -0.30, -0.30, -0.30, -0.30, -0.40, -0.50, -0.40, -0.20, 0.00, 0.00, 0.00, 0.00, -0.20, -0.40, -0.30, 0.00, 0.10, 0.15, 0.15, 0.10, 0.00, -0.30, -0.30, 0.05, 0.15, 0.20, 0.20, 0.15, 0.05, -0.30, -0.30, 0.00, 0.15, 0.20, 0.20, 0.15, 0.00, -0.30, -0.30, 0.05, 0.10, 0.15, 0.15, 0.10, 0.05, -0.30, -0.40, -0.20, 0.00, 0.05, 0.05, 0.00, -0.20, -0.40, -0.50, -0.40, -0.30, -0.30, -0.30, -0.30, -0.40, -0.50, ]; const BISHOP_BONUS: [Score; 64] = [ // A B C D E F G H -0.20, -0.10, -0.10, -0.10, -0.10, -0.10, -0.10, -0.20, -0.10, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, -0.10, -0.10, 0.00, 0.05, 0.10, 0.10, 0.05, 0.00, -0.10, -0.10, 0.05, 0.05, 0.10, 0.10, 0.05, 0.05, -0.10, -0.10, 0.00, 0.10, 0.10, 0.10, 0.10, 0.00, -0.10, -0.10, 0.10, 0.10, 0.10, 0.10, 0.10, 0.10, -0.10, -0.10, 0.25, 0.00, 0.00, 0.00, 0.00, 0.25, -0.10, -0.20, -0.10, -0.10, -0.10, -0.10, -0.10, -0.10, -0.20, ]; const ROOK_BONUS: [Score; 64] = [ // A B C D E F G H 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.05, 0.30, 0.30, 0.30, 0.30, 0.30, 0.30, 0.05, -0.05, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, -0.05, -0.05, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, -0.05, -0.05, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, -0.05, -0.05, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, -0.05, -0.05, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, -0.05, 0.00, 0.00, 0.00, 0.05, 0.05, 0.00, 0.00, 0.00 ]; const QUEEN_BONUS: [Score; 64] = [ // A B C D E F G H -0.20, -0.10, -0.10, -0.05, -0.05, -0.10, -0.10, -0.20, -0.10, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, -0.10, -0.10, 0.00, 0.05, 0.05, 0.05, 0.05, 0.00, -0.10, -0.05, 0.00, 0.05, 0.05, 0.05, 0.05, 0.00, -0.05, 0.00, 0.00, 0.05, 0.05, 0.05, 0.05, 0.00, -0.05, -0.10, 0.05, 0.05, 0.05, 0.05, 0.05, 0.00, -0.10, -0.10, 0.00, 0.05, 0.00, 0.00, 0.00, 0.00, -0.10, -0.20, -0.10, -0.10, -0.05, -0.05, -0.10, -0.10, -0.20 ]; const KING_BONUS: [Score; 64] = [ // A B C D E F G H -0.30, -0.40, -0.40, -0.50, -0.50, -0.40, -0.40, -0.30, -0.30, -0.40, -0.40, -0.50, -0.50, -0.40, -0.40, -0.30, -0.30, -0.40, -0.40, -0.50, -0.50, -0.40, -0.40, -0.30, -0.30, -0.40, -0.40, -0.50, -0.50, -0.40, -0.40, -0.30, -0.20, -0.30, -0.30, -0.40, -0.40, -0.30, -0.30, -0.20, -0.10, -0.20, -0.20, -0.20, -0.20, -0.20, -0.20, -0.10, 0.20, 0.20, 0.00, -0.10, -0.10, 0.00, 0.20, 0.20, 0.20, 0.10, 0.30, -0.20, 0.00, 0.10, 0.30, 0.20 ]; const KING_BONUS_ENGAME: [Score; 64] = [ // A B C D E F G H -0.50, -0.40, -0.30, -0.20, -0.20, -0.30, -0.40, -0.50, -0.30, -0.20, -0.10, 0.00, 0.00, -0.10, -0.20, -0.30, -0.30, -0.10, 0.20, 0.30, 0.30, 0.20, -0.10, -0.30, -0.30, -0.10, 0.30, 0.40, 0.40, 0.30, -0.10, -0.30, -0.30, -0.10, 0.30, 0.40, 0.40, 0.30, -0.10, -0.30, -0.30, -0.10, 0.20, 0.30, 0.30, 0.20, -0.10, -0.30, -0.30, -0.30, 0.00, 0.00, 0.00, 0.00, -0.30, -0.30, -0.50, -0.30, -0.30, -0.30, -0.30, -0.30, -0.30, -0.50 ]; impl Grossmeister { pub fn passer_mask(&self, color: Color) -> Bitboard { let black_pawns = self.board.piece_sets[Piece::PawnBlack as usize]; let white_pawns = self.board.piece_sets[Piece::Pawn as usize]; match color { Color::Black => { let mut front_fill = white_pawns.nort_fill().nort_one(); front_fill |= front_fill.east_one() | front_fill.west_one(); black_pawns & !front_fill } Color::White => { let mut front_fill = black_pawns.sout_fill().sout_one(); front_fill |= front_fill.east_one() | front_fill.west_one(); white_pawns & !front_fill } } } /// Return number of pawns above the king (+left/right) pub fn pawn_shield(&self, color: Color) -> f32 { let behind_pawns = match color { Color::White => self.board.piece_sets[Piece::Pawn as usize].sout_one(), Color::Black => self.board.piece_sets[Piece::PawnBlack as usize].nort_one(), }; let king = match color { Color::White => self.board.piece_sets[Piece::King as usize], Color::Black => self.board.piece_sets[Piece::KingBlack as usize], }; (behind_pawns & (king | king.west_one() | king.east_one())).pop_count() as f32 } /// Count the number of pawn islands of given color pub fn pawn_islands(&self, color: Color) -> f32 { let pawns = self.board.pieces_by_color(color)[Piece::Pawn as usize]; let fileset = pawns.nort_fill().sout_fill(); // Does not matter west/east, each island has both sides let islands_west_files = fileset & !fileset.east_one(); (islands_west_files.pop_count() / 8) as f32 } /// Compute total bonus for well-positioned pieces /// according to Piece-Square Tables pub fn pst_bonus(&self, color: Color, is_endgame: bool) -> f32 { self.board.pieces_by_color(color).iter().enumerate().fold(0., |total, (piece_index, bitboard)| { let pst = match Piece::from(piece_index).without_color() { Piece::Pawn => if is_endgame && (bitboard & self.passer_mask(color) > 0) { PAWN_BONUS_PASSER_ENDGAME } else { PAWN_BONUS } Piece::Knight => KNIGHT_BONUS, Piece::Bishop => BISHOP_BONUS, Piece::Rook => ROOK_BONUS, Piece::Queen => QUEEN_BONUS, Piece::King => if is_endgame { KING_BONUS_ENGAME } else { KING_BONUS } _ => panic!("Unreachable") }; total + bitboard.serialize().fold(0., |acc, square| { let pst_index = match color { Color::White => square.mirror(), Color::Black => square, } as usize; acc + pst[pst_index] }) }) } /// Count raw material of the given color pub fn material(&self, color: Color) -> f32 { self.board.pieces_by_color(color).iter().enumerate().fold(0., |acc, (piece_index, bitboard)| { acc + Piece::from(piece_index).static_eval() * bitboard.pop_count() as f32 }) } // Returns a value in [0, 240] representing how // much material is left in the game // Note: not related to actual material counting pub fn phase(&self) -> u8 { let knight_phase = 10; let bishop_phase = 10; let rook_phase = 20; let queen_phase = 40; let total_phase = knight_phase*4 + bishop_phase*4 + rook_phase*4 + queen_phase*2; // If you change it, make sure to update denominator in interpolation debug_assert_eq!(total_phase, 240); self.board.piece_sets.iter().enumerate().fold(0, |acc, (piece_index, &bitboard)| { acc + match Piece::from(piece_index).without_color() { Piece::King => 0, Piece::Pawn => 0, Piece::Knight => knight_phase, Piece::Bishop => bishop_phase, Piece::Rook => rook_phase, Piece::Queen => queen_phase, _ => panic!("Unreachable") } * bitboard.pop_count() }) } /// Evaluate a position relative to the current player pub fn evaluate(&self) -> Score { let color = self.board.color(); let opponent_color = color.flip(); let winnable = self.board.is_theoretically_winnable(color); let loseable = self.board.is_theoretically_winnable(opponent_color); if !winnable && !loseable { return 0.0 } let material_advantage = self.material(color) - self.material(opponent_color); let mobility_advantage = self.mobility(color) - self.mobility(opponent_color); let pawn_shield_advantage = self.pawn_shield(color) - self.pawn_shield(opponent_color); let pawn_islands_advantage = self.pawn_islands(opponent_color) - self.pawn_islands(color); // Middlegame eval, assumming all pieces are on the Board let middlegame_eval = mobility_advantage * 0.05 + pawn_shield_advantage * 0.20 + pawn_islands_advantage * 0.10 + (self.pst_bonus(color, false) - self.pst_bonus(opponent_color, false)); // Engame eval, assuming no pieces are left on the Board (only kings and pawns) let endgame_eval = mobility_advantage * 0.03 + pawn_shield_advantage * 0.05 + pawn_islands_advantage * 0.15 + (self.pst_bonus(color, true) - self.pst_bonus(opponent_color, true)); // Interpolate evalutaion based on amount of pieces to remove discontinuity let phase = self.phase(); let tapered_eval = (middlegame_eval * phase as f32 + endgame_eval * (240 - phase) as f32) / 240.; let eval = (material_advantage + tapered_eval) .min(if winnable { INFINITY } else { 0.0 }) // Can not score > 0 if not winnable .max(if loseable { -INFINITY } else { 0.0 }); // Can not score < 0 if not loseable (eval * 100.0).round() / 100.0 } /// Count pseudo-legal moves without actually generating them /// Also exclude all moves that put a piece under attack of a pawn - so called safe mobility pub fn mobility(&self, color: Color) -> f32 { let mut mobility = 0.; let opponent_occupancy = self.board.color_occupancy(color.flip()); let player_pieces = self.board.pieces_by_color(color); let opponent_pawns = match color { Color::Black => self.board.piece_sets[Piece::Pawn as usize], Color::White => self.board.piece_sets[Piece::PawnBlack as usize], }; let pawn_attacked_squares = opponent_pawns.serialize().fold(0u64, |acc, square| { acc | self.board.attacks.pawn[color.flip() as usize][square as usize] }); // Exclude squares controlled by enemy pawns from mobility let empty = self.board.empty() & !pawn_attacked_squares; for (piece_type, piece) in player_pieces.iter().enumerate() { match Piece::from(piece_type) { Piece::Pawn => { for source in piece.serialize() { let ep_bitboard = match self.board.ep_target { Some(square) => { let rank = square.rank(); if (rank == 2 && color == Color::Black) || (rank == 5 && color == Color::White) { square.to_bitboard() } else { 0 } } None => 0, }; mobility += (self.board.attacks.pawn[color as usize][source as usize] & (opponent_occupancy | ep_bitboard)).pop_count() as f32; mobility += (self.board.attacks.pawn_pushes[color as usize][source as usize] & empty).pop_count() as f32; } let able_to_double_push_mask = match color { Color::White => empty >> 8, Color::Black => empty << 8, }; for source in (*piece & able_to_double_push_mask).serialize() { mobility += (self.board.attacks.pawn_double_pushes[color as usize][source as usize] & empty).pop_count() as f32; } } Piece::King => { for source in piece.serialize() { mobility += (self.board.attacks.king[source as usize] & (empty | opponent_occupancy)).pop_count() as f32; // Castling let king_home_position = match color { Color::White => Square::E1, Color::Black => Square::E8, }; if *piece == king_home_position.to_bitboard() { for rook_square in player_pieces[Piece::Rook as usize] .serialize() .filter(|rook_square| rook_square.rank() == king_home_position.rank()) { match rook_square.file() { 0 => { let castle_line = [ king_home_position.west_one(), king_home_position.west_one().west_one(), ]; let all_empty = castle_line.iter().all(|square| empty & square.to_bitboard() > 0); let any_checks = castle_line.iter().any(|square| self.board.is_square_attacked(*square, color.flip())); if all_empty && !any_checks && self.board.castling_rights[color as usize][CastlingSide::Queen as usize] { mobility += 1.; } }, 7 => { let castle_line = [ king_home_position.east_one(), king_home_position.east_one().east_one(), ]; let all_empty = castle_line.iter().all(|square| empty & square.to_bitboard() > 0); let any_checks = castle_line.iter().any(|square| self.board.is_square_attacked(*square, color.flip())); if all_empty && !any_checks && self.board.castling_rights[color as usize][CastlingSide::King as usize] { mobility += 1.; } }, _ => {}, } } } } } Piece::Knight => { for source in piece.serialize() { mobility += (self.board.attacks.knight[source as usize] & (empty | opponent_occupancy)).pop_count() as f32; } } Piece::Bishop => { for source in piece.serialize() { mobility += (self.board.attacks.bishop(self.board.occupancy, source) & (empty | opponent_occupancy)).pop_count() as f32; } } Piece::Rook => { for source in piece.serialize() { mobility += (self.board.attacks.rook(self.board.occupancy, source) & (empty | opponent_occupancy)).pop_count() as f32; } } Piece::Queen => { // Do not account queen in mobility } incorrect_type => panic!("Incorrect piece type: {:?}", incorrect_type), } } mobility } } #[cfg(test)] mod tests { use crate::{board::{Board, io::IO}, moves::{Move, MoveKind}}; use super::*; #[test] fn castle_bonus() { assert_eq!(KING_BONUS[Square::E1.mirror() as usize], 0.0); assert!(KING_BONUS[Square::G1.mirror() as usize] > 0.0); assert!(KING_BONUS[Square::C1.mirror() as usize] > 0.0); assert!(KING_BONUS[Square::D1.mirror() as usize] < 0.0); assert!(KING_BONUS[Square::E2.mirror() as usize] < 0.0); assert_eq!(KING_BONUS[Square::E8 as usize], 0.0); assert!(KING_BONUS[Square::G8 as usize] > 0.0); assert!(KING_BONUS[Square::C8 as usize] > 0.0); assert!(KING_BONUS[Square::D8 as usize] < 0.0); assert!(KING_BONUS[Square::E2 as usize] < 0.0); } #[test] fn mobility() { let board = Board::new(); let gm = Grossmeister::new(board); let white = gm.mobility(Color::White); let black = gm.mobility(Color::Black); assert_eq!(white, 20.); assert_eq!(black, 20.); } #[test] fn material() { let board = Board::new(); let gm = Grossmeister::new(board); assert_eq!(gm.material(Color::Black), gm.material(Color::White)); } #[test] fn initial_eval() { let board = Board::new(); let gm = Grossmeister::new(board); assert_eq!(gm.evaluate(), 0.0); } #[test] fn king_tropism() { let board = Board::new(); let mut gm = Grossmeister::new(board); gm.board.make_move(Move { source: Square::D1, target: Square::F5, kind: MoveKind::Quiet }); let score = gm.evaluate(); gm.board.print(); println!("Score {}", score); assert!(score < 0.0); assert!(score > -1.0); } #[test] fn white_winning() { let fen = String::from("8/5pk1/6p1/R4b1p/3P4/1P2N3/P1r2PPP/R5K1 w - - 1 27"); let board = Board::from_FEN(fen); let gm = Grossmeister::new(board); let score = gm.evaluate(); gm.board.print(); println!("Score {}", score); assert!(score > 7.0); } #[test] fn black_winning() { let fen = String::from("8/p7/1k4K1/8/4P3/8/PP5r/8 w - - 1 38"); let board = Board::from_FEN(fen); let gm = Grossmeister::new(board); let score = gm.evaluate(); gm.board.print(); println!("Score {}", score); assert!(score < -3.0); } #[test] fn encourage_center_pawns() { let score1 = { let fen = String::from("rnbqkbnr/pppp1ppp/8/4p3/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 0 2"); let board = Board::from_FEN(fen); let gm = Grossmeister::new(board); let score = gm.evaluate(); gm.board.print(); println!("Score {}", score); score }; let score2 = { let fen = String::from("rnbqkbnr/pppp1ppp/8/4p3/2P5/8/PP1PPPPP/RNBQKBNR w KQkq - 0 2"); let board = Board::from_FEN(fen); let gm = Grossmeister::new(board); let score = gm.evaluate(); gm.board.print(); println!("Score {}", score); score }; assert!(score1 > score2); } #[test] fn discourage_edge_knights() { let score1 = { let fen = String::from("r1bqkbnr/pppp1ppp/2n5/4p3/4P3/5N2/PPPP1PPP/RNBQKB1R w KQkq - 2 3"); let board = Board::from_FEN(fen); let gm = Grossmeister::new(board); let score = gm.evaluate(); gm.board.print(); println!("Score {}", score); score }; let score2 = { let fen = String::from("r1bqkbnr/pppp1ppp/2n5/4p3/4P3/7N/PPPP1PPP/RNBQKB1R w KQkq - 2 3"); let board = Board::from_FEN(fen); let gm = Grossmeister::new(board); let score = gm.evaluate(); gm.board.print(); println!("Score {}", score); score }; assert!(score1 > score2); } #[test] fn mirrored_evaluation() { let score1 = { let fen = String::from("r3k2r/Pppp1ppp/1b3nbN/nP6/BBP1P3/q4N2/Pp1P2PP/R2Q1RK1 w kq - 0 1"); let board = Board::from_FEN(fen); let gm = Grossmeister::new(board); let score = gm.evaluate(); gm.board.print(); println!("Score {}", score); score }; let score2 = { let fen = String::from("r2q1rk1/pP1p2pp/Q4n2/bbp1p3/Np6/1B3NBn/pPPP1PPP/R3K2R b KQ - 0 1 "); let board = Board::from_FEN(fen); let gm = Grossmeister::new(board); let score = gm.evaluate(); gm.board.print(); println!("Score {}", score); score }; assert_eq!(score1.abs(), score2.abs()); } #[test] fn passer() { let fen = String::from("rnbqkbnr/ppp3pp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"); let board = Board::from_FEN(fen); let gm = Grossmeister::new(board); let mask = gm.passer_mask(Color::White); assert_eq!(mask, Square::E2.to_bitboard()); } #[test] fn no_passer() { let board = Board::new(); let gm = Grossmeister::new(board); let mask = gm.passer_mask(Color::White); assert_eq!(mask, 0); } }