private int Minimize(CheckersNode node, int depth)
{
if (depth == 0)
{
return(node.GetScore());
}
GenerateChildNodes(node);
for (int i = 0; i < node.children.Count; i++)
{
node.UpdateScore(false, Maximize(node.children[i], depth - 1));
}
return(node.GetScore());
}
//Reference:https://www.youtube.com/watch?v=zp3VMe0Jpf8
private CheckersNode RunMinimax(int player)
{
CheckersNode root = null;
if (player == 0)
{
root = new CheckersNode(size, player, null, player1Tokens, player2Tokens);
}
else
{
root = new CheckersNode(size, player, null, player2Tokens, player1Tokens);
}
root.BoardState = mainBoard;
int depth = maxMinimaxDepth;
Maximize(root, depth);
return(root.GetMaxChildNode());
}
private void AddMoveChildNode(Token token, int[,] board, int x, int y, Vector3 position, CheckersNode node, List <Token> opponentTokens, List <Token> playerTokens, bool isJump)
{
int originalX = token.xPosition;
int originalY = token.yPosition;
board[originalX, originalY] = -1;
board[x, y] = token.player;
token.gameObject.transform.position = position;
CheckersNode childNode = new CheckersNode(size, (token.player + 1) % 2, node, opponentTokens, playerTokens);
childNode.BoardState = board;
childNode.xStart = originalX;
childNode.yStart = originalY;
childNode.xEnd = x;
childNode.yEnd = y;
childNode.isJump = isJump;
board[originalX, originalY] = token.player;
board[x, y] = -1;
token.gameObject.transform.position = new Vector3(originalX, originalY, -1.0f);
node.children.Add(childNode);
}
private void GenerateChildNodes(CheckersNode node)
{
int[,] board = node.BoardState;
List <Token> playerTokens = new List <Token>();
for (int i = 0; i < node.playerTokens.Count; i++)
{
Token token = new Token(node.playerTokens[i]);
playerTokens.Add(token);
}
List <Token> opponentTokens = new List <Token>();
for (int i = 0; i < node.opponentTokens.Count; i++)
{
Token token = new Token(node.opponentTokens[i]);
opponentTokens.Add(token);
}
bool hasJumped = false;
//Find all possible moveable token positions
for (int i = 0; i < playerTokens.Count; i++)
{
Token token = playerTokens[i];
if (token.IsAlive)
{
//Check jumps
int x = token.xPosition - 2;
int y = token.yPosition + (token.player == 0 ? 2 : -2);
Vector3 position = new Vector3(x, y);
if (IsValidJumpPosition(position, token, board))
{
RemoveJumpedToken(position, token, opponentTokens, board);
AddMoveChildNode(token, board, x, y, position, node, opponentTokens, playerTokens, true);
RevertJumpedToken(position, token, opponentTokens, board);
hasJumped = true;
}
x = token.xPosition + 2;
position = new Vector3(x, y);
if (IsValidJumpPosition(position, token, board))
{
RemoveJumpedToken(position, token, opponentTokens, board);
AddMoveChildNode(token, board, x, y, position, node, opponentTokens, playerTokens, true);
RevertJumpedToken(position, token, opponentTokens, board);
hasJumped = true;
}
//We always want to prioritise jumping
if (!hasJumped)
{
//Check moves
x = token.xPosition - 1;
y = token.yPosition + (token.player == 0 ? 1 : -1);
position = new Vector3(x, y);
if (IsValidMovePosition(position, token, board))
{
AddMoveChildNode(token, board, x, y, position, node, opponentTokens, playerTokens, false);
}
x = token.xPosition + 1;
position = new Vector3(x, y);
if (IsValidMovePosition(position, token, board))
{
AddMoveChildNode(token, board, x, y, position, node, opponentTokens, playerTokens, false);
}
}
if (token.IsKing)
{
//Check king jumps
x = token.xPosition - 2;
y = token.yPosition + (token.player == 0 ? -2 : 2);
position = new Vector3(x, y);
if (IsValidJumpPosition(position, token, board))
{
RemoveJumpedToken(position, token, opponentTokens, board);
AddMoveChildNode(token, board, x, y, position, node, opponentTokens, playerTokens, true);
RevertJumpedToken(position, token, opponentTokens, board);
hasJumped = true;
}
x = token.xPosition + 2;
position = new Vector3(x, y);
if (IsValidJumpPosition(position, token, board))
{
RemoveJumpedToken(position, token, opponentTokens, board);
AddMoveChildNode(token, board, x, y, position, node, opponentTokens, playerTokens, true);
RevertJumpedToken(position, token, opponentTokens, board);
hasJumped = true;
}
if (!hasJumped)
{
//Check king moves
x = token.xPosition - 1;
y = token.yPosition + (token.player == 0 ? -1 : 1);
position = new Vector3(x, y);
if (IsValidMovePosition(position, token, board))
{
AddMoveChildNode(token, board, x, y, position, node, opponentTokens, playerTokens, false);
}
x = token.xPosition + 1;
position = new Vector3(x, y);
if (IsValidMovePosition(position, token, board))
{
AddMoveChildNode(token, board, x, y, position, node, opponentTokens, playerTokens, false);
}
}
}
}
}
}
private int Simulate(CheckersNode node, int winPlayer)
{
int[,] boardState = node.BoardState;
List <Token> playerTokens = new List <Token>();
List <Token> opponentTokens = new List <Token>();
int currentPlayer = node.player;
for (int i = 0; i < node.playerTokens.Count; i++)
{
Token playerToken = new Token(node.playerTokens[i]);
Token opponentToken = new Token(node.opponentTokens[i]);
playerTokens.Add(playerToken);
opponentTokens.Add(opponentToken);
}
int score = 0;
int currentMoveCount = moveCount;
int winner = -1;
bool instaLose = false;
while (winner == -1 && currentMoveCount < maxNumberOfMoves)
{
int index;
Vector3 destination;
bool isJump;
//Get random move
GetRandomMove(boardState, playerTokens, out index, out destination, out isJump);
if (index == -1)
{
//insta lose fam
instaLose = true;
break;
}
//Move
Token token = playerTokens[index];
if (isJump)
{
RemoveJumpedToken(destination, token, opponentTokens, boardState);
}
int originalX = token.xPosition;
int originalY = token.yPosition;
boardState[originalX, originalY] = -1;
boardState[(int)destination.x, (int)destination.y] = token.player;
token.gameObject.transform.position = destination;
//Swap players
currentPlayer = (currentPlayer + 1) % 2;
List <Token> temp = new List <Token>(playerTokens);
playerTokens.Clear();
playerTokens.AddRange(opponentTokens);
opponentTokens.Clear();
opponentTokens.AddRange(temp);
temp.Clear();
winner = CheckForWin(boardState, true);
currentMoveCount++;
}
if (instaLose)
{
if (currentPlayer == winPlayer)
{
score = 0;
}
else
{
for (int i = 0; i < size; i++)
{
for (int j = 0; j < size; j++)
{
if (boardState[i, j] == winPlayer)
{
score++;
}
}
}
}
}
else
{
if (winner == -1)
{
winner = CheckForWin(boardState, false);
}
if (winPlayer == winner)
{
for (int i = 0; i < size; i++)
{
for (int j = 0; j < size; j++)
{
if (boardState[i, j] == winPlayer)
{
score++;
}
}
}
}
}
return(score);
}
//Reference:https://www.youtube.com/watch?v=UXW2yZndl7U
private CheckersNode RunMCTS(int player)
{
CheckersNode root = null;
if (player == 0)
{
root = new CheckersNode(size, player, null, player1Tokens, player2Tokens);
}
else
{
root = new CheckersNode(size, player, null, player2Tokens, player1Tokens);
}
root.BoardState = mainBoard;
DateTime start = DateTime.Now;
int maxDepth = 0;
while ((DateTime.Now - start).TotalMilliseconds < maxMCTSTime)
{
CheckersNode current = root;
int depth = 0;
//Selection
while (current.children.Count != 0)
{
current = current.GetChildWithBestUCB1();
depth++;
}
if (maxDepth < depth)
{
maxDepth = depth;
}
//Simulation
if (current.totalPlayouts == 0)
{
int score = Simulate(current, player);
//Back Propagate
current.BackPropagate(score);
}
else
{
//Expansion
GenerateChildNodes(current);
}
}
totalMCTSDepth += maxDepth;
if (root.children.Count > 0)
{
//Find node with best score
float bestScore = root.children[0].GetScore() / root.children[0].totalPlayouts;
int selectedIndex = 0;
for (int i = 1; i < root.children.Count; i++)
{
float score = root.children[i].GetScore() / root.children[i].totalPlayouts;
if (bestScore < score)
{
bestScore = score;
selectedIndex = i;
}
}
return(root.children[selectedIndex]);
}
else
{
return(null);
}
}
// Update is called once per frame
void Update()
{
if (!stopGame)
{
if (activePlayer == 0)
{
if (Input.GetMouseButtonDown(0) && !doubleAI)
{
RaycastHit hit;
Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
if (currentPlayState == PlayState.SELECTION)
{
if (Physics.Raycast(ray, out hit, Mathf.Infinity, LayerMask.GetMask("Token")))
{
selectedToken = GetSelectedToken(player1Tokens, hit.transform.position);
if (selectedToken != null && selectedToken.IsAlive)
{
currentPlayState = PlayState.PLACEMENT;
}
else
{
selectedToken = null;
}
}
}
else
{
if (Physics.Raycast(ray, out hit, Mathf.Infinity, LayerMask.GetMask("Board")))
{
Vector3 hitPosition = hit.transform.position;
if (IsValidMovePosition(hitPosition, selectedToken, mainBoard))
{
UpdateSelectedTokenPosition(hitPosition, selectedToken, mainBoard);
stopGame = CheckForWin(mainBoard, true) != -1;
gameText.text = "Player " + (activePlayer + 1) + " wins!";
activePlayer = (activePlayer + 1) % 2;
moveCount++;
}
else if (IsValidJumpPosition(hitPosition, selectedToken, mainBoard))
{
RemoveJumpedToken(hitPosition, selectedToken, player2Tokens, mainBoard);
UpdateSelectedTokenPosition(hitPosition, selectedToken, mainBoard);
stopGame = CheckForWin(mainBoard, true) != -1;
gameText.text = "Player " + (activePlayer + 1) + " wins!";
activePlayer = (activePlayer + 1) % 2;
moveCount++;
}
}
}
}
if (doubleAI)
{
bool instaLose = false;
if (moveCount == 0)
{
//Reference:http://www.quadibloc.com/other/bo1211.htm
//Make the best move possible (5,2) to (6,3)
Vector3 tokenPosition = new Vector3(5, 2, -1.0f);
Vector3 movePosition = new Vector3(6, 3);
Token tokenToMove = GetSelectedToken(player1Tokens, tokenPosition);
UpdateSelectedTokenPosition(movePosition, tokenToMove, mainBoard);
}
else
{
//AI code
CheckersNode node = RunMCTS(activePlayer);
mctsTurns++;
if (node != null)
{
Vector3 tokenPosition = new Vector3(node.xStart, node.yStart, -1.0f);
Vector3 movePosition = new Vector3(node.xEnd, node.yEnd);
Token tokenToMove = GetSelectedToken(player1Tokens, tokenPosition);
Debug.Assert(tokenToMove.IsAlive);
if (node.isJump)
{
RemoveJumpedToken(movePosition, tokenToMove, player2Tokens, mainBoard);
}
UpdateSelectedTokenPosition(movePosition, tokenToMove, mainBoard);
}
else
{
instaLose = true;
}
}
if (!instaLose)
{
stopGame = CheckForWin(mainBoard, true) != -1;
if (stopGame)
{
gameText.text = "Player " + (activePlayer + 1) + " wins!";
player1Wins++;
}
activePlayer = (activePlayer + 1) % 2;
moveCount++;
}
else
{
//Player 2 wins
stopGame = true;
gameText.text = "Player " + (((activePlayer + 1) % 2) + 1) + " wins!";
player2Wins++;
}
}
}
else
{
//AI code
DateTime start = DateTime.Now;
CheckersNode node = RunMinimax(activePlayer);
totalMinimaxTime += (DateTime.Now - start).TotalMilliseconds;
minimaxTurns++;
if (node != null)
{
Vector3 tokenPosition = new Vector3(node.xStart, node.yStart, -1.0f);
Vector3 movePosition = new Vector3(node.xEnd, node.yEnd);
Token tokenToMove = GetSelectedToken(player2Tokens, tokenPosition);
Debug.Assert(tokenToMove.IsAlive);
if (node.isJump)
{
RemoveJumpedToken(movePosition, tokenToMove, player1Tokens, mainBoard);
}
UpdateSelectedTokenPosition(movePosition, tokenToMove, mainBoard);
stopGame = CheckForWin(mainBoard, true) != -1;
if (stopGame)
{
gameText.text = "Player " + (activePlayer + 1) + " wins!";
player2Wins++;
}
activePlayer = (activePlayer + 1) % 2;
moveCount++;
}
else
{
//Player 1 wins
stopGame = true;
gameText.text = "Player " + (((activePlayer + 1) % 2) + 1) + " wins!";
player1Wins++;
}
}
if (moveCount == maxNumberOfMoves)
{
stopGame = true;
int winner = CheckForWin(mainBoard, false);
gameText.text = "Player " + (winner + 1) + " wins!";
if (winner == 0)
{
player1Wins++;
}
else
{
player2Wins++;
}
}
if (!stopGame)
{
gameText.text = "Player " + (activePlayer + 1);
}
DummyObjectPool.Instance.ResetAll();
}
else
{
currentIteration++;
if (currentIteration < numberOfIterations)
{
ResetBoard();
}
else
{
if (gameText.text != "Finished")
{
gameText.text = "Finished";
WriteLog();
Application.Quit();
}
}
}
}
