Added threading, optimizations

.vscode/settings.json

@@ -46,6 +46,9 @@
         "stdexcept": "cpp",
         "streambuf": "cpp",
         "cinttypes": "cpp",
-        "typeinfo": "cpp"
+        "typeinfo": "cpp",
+        "thread": "cpp",
+        "condition_variable": "cpp",
+        "mutex": "cpp"
     }
 }

.vscode/tasks.json

@@ -25,7 +25,7 @@
             ],
             "group": {
                 "kind": "build",
-                "isDefault": false
+                "isDefault": true
             },
             "detail": "Task generated by Debugger."
         },
@@ -55,7 +55,7 @@
             ],
             "group": {
                 "kind": "build",
-                "isDefault": true
+                "isDefault": false
             },
             "detail": ""
         }

board.cpp

@@ -559,7 +559,7 @@ std::vector<int> Board::get_moves_for_space(int x, int y, bool check_for_check)
 
     if (KING == piece_type)
     {
-        int king_offsets[8][2] = {{-1,-1},{0,-1},{1,-1},{-1,0},{1,0},{1,-1},{1,0},{1,1}};
+        int king_offsets[8][2] = {{-1,-1},{0,-1},{1,-1},{-1,0},{1,0},{-1,1},{0,1},{1,1}};
         for(int i = 0; i < 8; i++)
         {
             int x1 = x+king_offsets[i][0];
@@ -794,13 +794,26 @@ void Board::do_move(int space_from, int space_to, bool holding_k)
 
     if (castling)
     {
+        game_board[xt][yt] = Piece();
+        game_board[xf][yf] = Piece();
+        if (xt == 7)
+        {
+            xt = 6;
+            xf = 5;
+        }
+        else
+        {
+            xt = 2;
+            xf = 3;
+        }
         game_board[xf][yf] = target_piece;
+        game_board[xt][yt] = cur_piece;
     }
     else
     {
         game_board[xf][yf] = Piece();
+        game_board[xt][yt] = cur_piece;
     }
-    game_board[xt][yt] = cur_piece;
 
     if(is_check(enemy_team))
     {
@@ -813,6 +826,144 @@ void Board::do_move(int space_from, int space_to, bool holding_k)
     selected_space = -1;
 }
 
+int Board::get_attackers_for_space(int space_to)
+{
+    int xt=space_to%BOARD_SIZE,yt=space_to/BOARD_SIZE;
+
+    if (space_to < 0 || space_to > BOARD_SIZE*BOARD_SIZE || game_board[xt][yt].get_team() == NO_TEAM)
+    {
+        return 0;
+    }
+
+    int num_attackers = 0;
+
+    Team enemy_team = (game_board[xt][yt].get_team() == WHITE)?BLACK:WHITE;
+
+    int forward_direction = (game_board[xt][yt].get_team() == WHITE)?-1:1;
+
+    if (game_board[xt][yt].get_type() == PAWN && en_passant == xt+(yt-forward_direction)*BOARD_SIZE)
+    {
+        int en_passent_offsets[2][2] = {{-1,0},{1,0}};
+
+        for(int i = 0; i < 2; i++)
+        {
+            int xf = xt+en_passent_offsets[i][0], yf = yt+en_passent_offsets[i][1];
+
+            if (xf < 0 || xf >= BOARD_SIZE || yf < 0 || yf >= BOARD_SIZE)
+            {
+                continue;
+            }
+
+            if (game_board[xf][yf].get_team() != enemy_team || game_board[xf][yf].get_type() != PAWN)
+            {
+                continue;
+            }
+
+            num_attackers++;
+        }
+    }
+
+    int pawn_offsets[2][2] = {{-1, -1*forward_direction},{1, -1*forward_direction}};
+    for(int i = 0; i < 2; i++)
+    {
+        int xf = xt+pawn_offsets[i][0], yf = yt+pawn_offsets[i][1];
+
+        if (xf < 0 || xf >= BOARD_SIZE || yf < 0 || yf >= BOARD_SIZE)
+        {
+            continue;
+        }
+
+        if (game_board[xf][yf].get_team() != enemy_team || game_board[xf][yf].get_type() != PAWN)
+        {
+            continue;
+        }
+
+        num_attackers++;
+    }
+
+    int king_offsets[8][2] = {{-1,-1},{0,-1},{1,-1},{-1,0},{1,0},{1,-1},{1,0},{1,1}};
+
+    for(int i = 0; i < 8; i++)
+    {
+        int xf = xt+king_offsets[i][0], yf = yt+king_offsets[i][1];
+
+        if (xf < 0 || xf >= BOARD_SIZE || yf < 0 || yf >= BOARD_SIZE)
+        {
+            continue;
+        }
+
+        if (game_board[xf][yf].get_team() != enemy_team || (game_board[xf][yf].get_type() != KING && game_board[xf][yf].get_vis() != HIDDEN))
+        {
+            continue;
+        }
+
+        num_attackers++;
+    }
+    
+    int knight_offsets[8][2] = {{-1,2},{1,2},{-1,-2},{1,-2},{-2,1},{2,1},{-2,-1},{2,-1}};
+    for(int i = 0; i < 8; i++)
+    {
+        int xf = xt+knight_offsets[i][0], yf = yt+knight_offsets[i][1];
+
+        if (xf < 0 || xf >= BOARD_SIZE || yf < 0 || yf >= BOARD_SIZE)
+        {
+            continue;
+        }
+
+        if (game_board[xf][yf].get_team() != enemy_team || game_board[xf][yf].get_type() != KNIGHT)
+        {
+            continue;
+        }
+
+        num_attackers++;
+    }
+
+    int queen_bishop_offsets[28][2] = {{1,1},{2,2},{3,3},{4,4},{5,5},{6,6},{7,7},
+                                        {-1,1},{-2,2},{-3,3},{-4,4},{-5,5},{-6,6},{-7,7},
+                                        {1,-1},{2,-2},{3,-3},{4,-4},{5,-5},{6,-6},{7,-7},
+                                        {-1,-1},{-2,-2},{-3,-3},{-4,-4},{-5,-5},{-6,-6},{-7,-7}};
+    for(int i = 0; i < 28; i++)
+    {
+        int xf = xt+queen_bishop_offsets[i][0], yf = yt+queen_bishop_offsets[i][1];
+
+        if (xf < 0 || xf >= BOARD_SIZE || yf < 0 || yf >= BOARD_SIZE)
+        {
+            continue;
+        }
+
+        if (game_board[xf][yf].get_team() != enemy_team || (game_board[xf][yf].get_type() != QUEEN && game_board[xf][yf].get_type() != BISHOP && game_board[xf][yf].get_vis() != SHOWN))
+        {
+            continue;
+        }
+
+        num_attackers++;
+    }
+
+    int queen_rook_offsets[28][2] = {{1,0},{2,0},{3,0},{4,0},{5,0},{6,0},{7,0},
+                                    {0,1},{0,2},{0,3},{0,4},{0,5},{0,6},{0,7},
+                                    {-1,0},{-2,0},{-3,0},{-4,0},{-5,0},{-6,0},{-7,0},
+                                    {0,-1},{0,-2},{0,-3},{0,-4},{0,-5},{0,-6},{0,-7}};
+
+    for(int i = 0; i < 28; i++)
+    {
+        int xf = xt+queen_rook_offsets[i][0], yf = yt+queen_rook_offsets[i][1];
+
+        if (xf < 0 || xf >= BOARD_SIZE || yf < 0 || yf >= BOARD_SIZE)
+        {
+            continue;
+        }
+
+        if (game_board[xf][yf].get_team() != enemy_team || (game_board[xf][yf].get_type() != QUEEN && game_board[xf][yf].get_type() != ROOK && game_board[xf][yf].get_vis() != SHOWN))
+        {
+            continue;
+        }
+
+        num_attackers++;
+    }
+
+    return num_attackers;
+}
+
 MoveType Board::can_move(int space_from, int space_to)
 {
     if (space_from < 0 || space_to < 0 || space_from >= BOARD_SIZE*BOARD_SIZE || space_to >= BOARD_SIZE*BOARD_SIZE)
@@ -862,7 +1013,7 @@ MoveType Board::can_move(int space_from, int space_to)
 
 bool Board::does_move_solve_check(int space_from, int space_to)
 {
-    Board test_board(make_FEN());
+    Board test_board(*this);
     test_board.do_move(space_from, space_to, false);
     return !test_board.is_check(game_board[space_from%BOARD_SIZE][space_from/BOARD_SIZE].get_team());
 }

board.hpp

@@ -39,6 +39,8 @@ public:
     bool is_mate(Team team);
 
     void do_move(int space_from, int space_to, bool holding_k);
+
+    int get_attackers_for_space(int space_to);
 private:
     Piece game_board[BOARD_SIZE][BOARD_SIZE];
     Team active_color;

game.cpp

@@ -5,6 +5,7 @@
 #include <algorithm>
 #include <cstdlib>
 #include <limits>
+#include <thread>
 
 uint64_t time_milli() {
     using namespace std::chrono;
@@ -71,6 +72,8 @@ void Game::tick()
             x/=SPRITE_SIZE;
             y/=SPRITE_SIZE;
             process_click(x,y);
+
+            draw();
         }
     }
 
@@ -115,10 +118,16 @@ void Game::process_click(int x, int y)
 
 void Game::do_ai_move()
 {
+    std::vector<std::thread> threads;
+    std::mutex mut_result_check;
     int best_move_weight = std::numeric_limits<int>::min();
     int best_move_from = -1;
     int best_move_to = -1;
     bool best_move_makes_queen = false;
+    int a = std::numeric_limits<int>::min();
+
+    Board board_copy = Board(board);
+
     for(int x = 0; x < BOARD_SIZE; x++)
     {
         for(int y = 0; y < BOARD_SIZE; y++)
@@ -126,178 +135,239 @@ void Game::do_ai_move()
             Piece cur_piece = board.get_piece(x,y);
             if (cur_piece.get_team() == BLACK)
             {
-                std::vector<int> piece_moves = board.get_moves_for_space(x,y, true);
+                threads.push_back(std::thread([&mut_result_check, &best_move_weight, &best_move_from, &best_move_to, &best_move_makes_queen, &a, x, y, &board_copy](){
-                for (unsigned int i = 0; i < piece_moves.size(); i++)
+                    std::vector<int> piece_moves = board_copy.get_moves_for_space(x,y, true);
-                {
+                    Piece cur_piece = board_copy.get_piece(x,y);
-                    Board test_board(board.make_FEN());
-                    test_board.do_move(x+y*BOARD_SIZE, piece_moves[i], false);
-
-                    int board_value = minimax(test_board, 3, std::numeric_limits<int>::min(), std::numeric_limits<int>::max(), false);
-
-                    if (board_value > best_move_weight)
-                    {
-                        best_move_weight = board_value;
-                        best_move_from = x+y*BOARD_SIZE;
-                        best_move_to = piece_moves[i];
-                        best_move_makes_queen = false;
-                    }
-
-                    if (cur_piece.get_type() == PAWN || (piece_moves[i]/BOARD_SIZE) == 7)
-                    {
-                        Board test_board1 = Board(board.make_FEN());
-                        test_board1.do_move(x+y*BOARD_SIZE, piece_moves[i], true);
-
-                        if (test_board1.make_FEN().compare(test_board.make_FEN()) != 0)
-                        {
-                            board_value = minimax(test_board1, 3, std::numeric_limits<int>::min(), std::numeric_limits<int>::max(), false);
-
-                            if (board_value > best_move_weight)
-                            {
-                                best_move_weight = board_value;
-                                best_move_from = x+y*BOARD_SIZE;
-                                best_move_to = piece_moves[i];
-                                best_move_makes_queen = true;
-                            }
-                        }
-                    }
-                }
-            }
-        }
-    }
-
-    board.do_move(best_move_from, best_move_to, best_move_makes_queen);
-}
-
-int Game::minimax(Board current_board, int depth, int a, int b, bool maximizing)
-{
-    if (depth == 0 || current_board.is_mate(current_board.get_active_color()))
-    {
-        return board_heuristic(current_board);
-    }
-
-    if (maximizing)
-    {
-        int best_move_weight = std::numeric_limits<int>::min();
-        for(int x = 0; x < BOARD_SIZE; x++)
-        {
-            for(int y = 0; y < BOARD_SIZE; y++)
-            {
-                Piece cur_piece = current_board.get_piece(x,y);
-                if (cur_piece.get_team() == BLACK)
-                {
-                    std::vector<int> piece_moves = current_board.get_moves_for_space(x,y, true);
                     for (unsigned int i = 0; i < piece_moves.size(); i++)
                     {
-                        Board test_board(current_board.make_FEN());
+                        Board test_board(board_copy);
                         test_board.do_move(x+y*BOARD_SIZE, piece_moves[i], false);
 
-                        int board_value = minimax(test_board, depth-1, a, b, false);
+                        int board_value = minimax(test_board, 4, 5, a, std::numeric_limits<int>::max(), false);
 
+                        mut_result_check.lock();
                         if (board_value > best_move_weight)
                         {
                             best_move_weight = board_value;
-                        }
+                            best_move_from = x+y*BOARD_SIZE;
-
+                            best_move_to = piece_moves[i];
-                        if (best_move_weight >= b)
+                            best_move_makes_queen = false;
-                        {
-                            return best_move_weight;
                         }
 
                         if (best_move_weight > a)
                         {
                             a = best_move_weight;
                         }
+                        mut_result_check.unlock();
 
                         if (cur_piece.get_type() == PAWN || (piece_moves[i]/BOARD_SIZE) == 7)
                         {
-                            test_board = Board(current_board.make_FEN());
+                            Board test_board1 = Board(board_copy);
-                            test_board.do_move(x+y*BOARD_SIZE, piece_moves[i], true);
+                            test_board1.do_move(x+y*BOARD_SIZE, piece_moves[i], true);
 
-                            board_value = minimax(test_board, depth-1, a, b, false);
+                            if (test_board1.make_FEN().compare(board_copy.make_FEN()) != 0)
-
-                            if (board_value > best_move_weight)
                             {
-                                best_move_weight = board_value;
+                                board_value = minimax(test_board1, 4, 5, a, std::numeric_limits<int>::max(), false);
-                            }
 
-                            if (best_move_weight >= b)
+                                mut_result_check.lock();
-                            {
+                                if (board_value > best_move_weight)
-                                return best_move_weight;
+                                {
-                            }
+                                    best_move_weight = board_value;
+                                    best_move_from = x+y*BOARD_SIZE;
+                                    best_move_to = piece_moves[i];
+                                    best_move_makes_queen = true;
+                                }
 
-                            if (best_move_weight > a)
+                                if (best_move_weight > a)
-                            {
+                                {
-                                a = best_move_weight;
+                                    a = best_move_weight;
+                                }
+                                mut_result_check.unlock();
                             }
                         }
                     }
+                }));
+            }
+        }
+    }
+
+    for(std::thread& cur_thread : threads)
+    {
+        cur_thread.join();
+    }
+
+    board.do_move(best_move_from, best_move_to, best_move_makes_queen);
+}
+
+int Game::minimax(Board current_board, int depth, int max_depth, int a, int b, bool maximizing)
+{
+    if (depth == 0 || current_board.is_mate(current_board.get_active_color()))
+    {
+        return board_heuristic(current_board);
+    }
+
+    int best_move_weight = maximizing?std::numeric_limits<int>::min():std::numeric_limits<int>::max();
+    bool a_eject = false, b_eject  = false;
+
+    std::vector<std::thread> threads;
+    std::mutex mut_result_check;
+    int finished_threads = 0;
+    std::mutex mut_finished_threads;
+
+    for(int x = 0; x < BOARD_SIZE && !a_eject && !b_eject; x++)
+    {
+        for(int y = 0; y < BOARD_SIZE && !a_eject && !b_eject; y++)
+        {
+            if (current_board.get_piece(x,y).get_team() == (maximizing?BLACK:WHITE))
+            {
+                if (depth == max_depth-1)
+                {
+                    if (threads.size()-finished_threads <= 4)
+                    {
+                        threads.push_back(std::thread([&finished_threads, &mut_finished_threads, &mut_result_check, current_board, x, y, depth, max_depth, &best_move_weight, &a, &b, &a_eject, &b_eject, maximizing](){
+                            minimax_evaluate(mut_result_check, current_board, x, y, depth, max_depth, best_move_weight, a, b, a_eject, b_eject, maximizing);
+                            mut_finished_threads.lock();
+                            finished_threads++;
+                            mut_finished_threads.unlock();
+                        }));
+                    }
+                    else
+                    {
+                        minimax_evaluate(mut_result_check, current_board, x, y, depth, max_depth, best_move_weight, a, b, a_eject, b_eject, maximizing);
+                    }
+                }
+                else
+                {
+                    minimax_evaluate(mut_result_check, current_board, x, y, depth, max_depth, best_move_weight, a, b, a_eject, b_eject, maximizing);
                 }
             }
         }
+    }
 
-        return best_move_weight;
+    for (std::thread& cur_thread : threads)
+    {
+        cur_thread.join();
+    }
+
+    return best_move_weight;
+}
+
+void Game::minimax_evaluate(std::mutex& mut_result_check, Board current_board, int x, int y, int depth, int max_depth, int& best_move_weight, int& a, int& b, bool& a_eject, bool& b_eject, bool maximizing)
+{   
+    Piece cur_piece = current_board.get_piece(x,y);
+    std::vector<int> piece_moves = current_board.get_moves_for_space(x,y, true);
+
+    if (maximizing)
+    {
+        for (unsigned int i = 0; i < piece_moves.size(); i++)
+        {
+            Board test_board(current_board);
+            test_board.do_move(x+y*BOARD_SIZE, piece_moves[i], false);
+
+            int board_value = minimax(test_board, depth-1, max_depth, a, b, false);
+
+            mut_result_check.lock();
+            if (board_value > best_move_weight)
+            {
+                best_move_weight = board_value;
+            }
+
+            if (best_move_weight >= b)
+            {
+                b_eject = true;
+                mut_result_check.unlock();
+                return;
+            }
+
+            if (best_move_weight > a)
+            {
+                a = best_move_weight;
+            }
+            mut_result_check.unlock();
+
+            if (cur_piece.get_type() == PAWN || (piece_moves[i]/BOARD_SIZE) == (maximizing?7:0))
+            {
+                test_board = Board(current_board);
+                test_board.do_move(x+y*BOARD_SIZE, piece_moves[i], true);
+
+                board_value = minimax(test_board, depth-1, max_depth, a, b, false);
+
+                mut_result_check.lock();
+                if (board_value > best_move_weight)
+                {
+                    best_move_weight = board_value;
+                }
+
+                if (best_move_weight >= b)
+                {
+                    b_eject = true;
+                    mut_result_check.unlock();
+                    return;
+                }
+
+                if (best_move_weight > a)
+                {
+                    a = best_move_weight;
+                }
+                mut_result_check.unlock();
+            }
+        }
     }
     else
     {
-        int best_move_weight = std::numeric_limits<int>::max();
+        for (unsigned int i = 0; i < piece_moves.size(); i++)
-        for(int x = 0; x < BOARD_SIZE; x++)
         {
-            for(int y = 0; y < BOARD_SIZE; y++)
+            Board test_board(current_board);
+            test_board.do_move(x+y*BOARD_SIZE, piece_moves[i], false);
+
+            int board_value = minimax(test_board, depth-1, max_depth, a, b, true);
+
+            mut_result_check.lock();
+            if (board_value < best_move_weight)
             {
-                Piece cur_piece = current_board.get_piece(x,y);
+                best_move_weight = board_value;
-                if (cur_piece.get_team() == WHITE)
+            }
+
+            if (best_move_weight <= a)
+            {
+                a_eject = true;
+                mut_result_check.unlock();
+                return;
+            }
+
+            if (best_move_weight < b)
+            {
+                b = best_move_weight;
+            }
+            mut_result_check.unlock();
+
+            if (cur_piece.get_type() == PAWN || (piece_moves[i]/BOARD_SIZE) == (maximizing?7:0))
+            {
+                test_board = Board(current_board);
+                test_board.do_move(x+y*BOARD_SIZE, piece_moves[i], true);
+
+                board_value = minimax(test_board, depth-1, max_depth, a, b, true);
+
+                mut_result_check.lock();
+                if (board_value < best_move_weight)
                 {
-                    std::vector<int> piece_moves = current_board.get_moves_for_space(x,y, true);
+                    best_move_weight = board_value;
-                    for (unsigned int i = 0; i < piece_moves.size(); i++)
-                    {
-                        Board test_board(current_board.make_FEN());
-                        test_board.do_move(x+y*BOARD_SIZE, piece_moves[i], false);
-
-                        int board_value = minimax(test_board, depth-1, a, b, true);
-
-                        if (board_value < best_move_weight)
-                        {
-                            best_move_weight = board_value;
-                        }
-
-                        if (best_move_weight <= a)
-                        {
-                            return best_move_weight;
-                        }
-
-                        if (best_move_weight < b)
-                        {
-                            b = best_move_weight;
-                        }
-
-                        if (cur_piece.get_type() == PAWN || (piece_moves[i]/BOARD_SIZE) == 0)
-                        {
-                            test_board = Board(current_board.make_FEN());
-                            test_board.do_move(x+y*BOARD_SIZE, piece_moves[i], true);
-
-                            board_value = minimax(test_board, depth-1, a, b, true);
-
-                            if (board_value < best_move_weight)
-                            {
-                                best_move_weight = board_value;
-                            }
-
-                            if (best_move_weight <= a)
-                            {
-                                return best_move_weight;
-                            }
-
-                            if (best_move_weight < b)
-                            {
-                                b = best_move_weight;
-                            }
-                        }
-                    }
                 }
+
+                if (best_move_weight <= a)
+                {
+                    a_eject = true;
+                    mut_result_check.unlock();
+                    return;
+                }
+
+                if (best_move_weight < b)
+                {
+                    b = best_move_weight;
+                }
+                mut_result_check.unlock();
             }
         }
-
-        return best_move_weight;
     }
 }
 
@@ -305,7 +375,12 @@ int Game::board_heuristic(Board current_board)
 {
     int heuristic = 0;
     int piece_weights[2][7] = {{-900, -90, -30, -30, -50, -10, 0}, {900, 90, 30, 30, 50, 10, 0}};
-
+    
+    ///Calculate the weight of an unknown piece for both teams
+    //The weight of an unknown piece is 2 times the average of the remaining unrevealed pieces
+    //The weight is 2 times so that the AI understands that the hidden pieces are valuable hidden, otherwise the average
+    //is less than that of Rooks, making the AI always reveal its rooks.
+    //In order to still sometimes prefer revealing, the number of vulnerabilities will be considered later into a pieces weight.
     int unknown_white_count = 0;
     int unknown_black_count = 0;
     for(int x = 0; x < BOARD_SIZE; x++)
@@ -323,12 +398,12 @@ int Game::board_heuristic(Board current_board)
             {
                 if (cur_piece.get_team() == WHITE)
                 {
-                    piece_weights[WHITE][UNKNOWN] += piece_weights[WHITE][cur_piece.get_type()];
+                    piece_weights[WHITE][UNKNOWN] += 2*piece_weights[WHITE][cur_piece.get_type()];
                     unknown_white_count++;
                 }
                 else
                 {
-                    piece_weights[BLACK][UNKNOWN] += piece_weights[BLACK][cur_piece.get_type()];
+                    piece_weights[BLACK][UNKNOWN] += 2*piece_weights[BLACK][cur_piece.get_type()];
                     unknown_black_count++;
                 }
             }
@@ -360,7 +435,11 @@ int Game::board_heuristic(Board current_board)
                 cur_piece = Piece(UNKNOWN, cur_piece.get_team(), SHOWN);
             }
 
-            heuristic += piece_weights[cur_piece.get_team()][cur_piece.get_type()];
+            int adden = piece_weights[cur_piece.get_team()][cur_piece.get_type()];
+
+            int found_attackers = current_board.get_attackers_for_space(x+y*BOARD_SIZE);
+
+            heuristic += adden/((found_attackers!=0)?2:1);
         }
     }
 

game.hpp

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <mutex>
+
 #include "SDL2/SDL.h"
 
 #include "board.hpp"
@@ -18,8 +20,9 @@ private:
     void process_click(int x, int y);
 
     void do_ai_move();
-    int minimax(Board current_board, int depth, int a, int b, bool maximizing);
+    static int minimax(Board current_board, int depth, int max_depth, int a, int b, bool maximizing);
-    int board_heuristic(Board current_board);
+    static void minimax_evaluate(std::mutex& mut_result_check, Board current_board, int x, int y, int depth, int max_depth, int& best_move_weight, int& a, int& b, bool& a_eject, bool& b_eject, bool maximizing);
+    static int board_heuristic(Board current_board);
 
     SDL_Window* window;
     SDL_Surface* surface;