// This gets called it "manual" is false. It's where the AI is actually given the reigns.
public override void DoMove()
{
VBoard internalVBoard = new VBoard(bm, playerNumber);
Vector3Int bestMove = new Vector3Int(-1, -1, -1);
bool doesWin = false;
bestMove = internalVBoard.PickMove(numFutureTurnsCalculated, priorWeight, ref doesWin);
// now, if the player does win, we have to make them win in the least number of possible moves.
Debug.Log("Does Win? " + doesWin);
if (!doesWin)
{
for (int i = numFutureTurnsCalculated - 1; i >= 0; i--)
{
doesWin = false;
Vector3Int newBestMove = internalVBoard.PickMove(i, priorWeight, ref doesWin);
if (!doesWin)
{
break;
}
else
{
bestMove = newBestMove;
}
}
}
if (bestMove.x < 0)
{
Debug.Log("Error with the AI - couldn't find a valid move!");
}
pieces[bestMove.x].RealizeMove(new Vector2Int(bestMove.y, bestMove.z));
bm.hasFinishedMove = true;
}
// evaluates the board from player1's perspective
// we maximize iff curPlayer is true
// doesn't work if n<0!
float EvaluateBoard(int n, float priorWeight, ref bool doesWin)
{
if (n == 0)
{
return(EvaluateBoard(ref doesWin));
}
CheckIfWin(ref doesWin);
if (doesWin == true)
{
return(0);
}
// short-circuit if you are going to win in fewer moves!
float optimalValue = curPlayer ? Mathf.NegativeInfinity : Mathf.Infinity;
Vector2Int[] myPieces = curPlayer ? player1Pieces : player2Pieces;
for (int i = 0; i < myPieces.Length; i++)
{
if (doesWin)
{
break;
}
Vector2Int piece = myPieces[i];
foreach (Vector2Int moveToPos in GetMoves(piece))
{
if (doesWin)
{
break;
}
VBoard newBoard = new VBoard(this);
newBoard.boardArr[piece.x, piece.y] = false;
newBoard.boardArr[moveToPos.x, moveToPos.y] = true;
(curPlayer ? newBoard.player1Pieces : newBoard.player2Pieces)[i] = moveToPos;
float newValue = newBoard.EvaluateBoard(n - 1, priorWeight, ref doesWin);
if (doesWin || (curPlayer ? (newValue > optimalValue) : (newValue < optimalValue)))
{
optimalValue = newValue;
}
}
}
float currentValue = EvaluateBoard(ref doesWin);
return(currentValue * priorWeight + optimalValue * (1 - priorWeight));
}
// HERE we finally produce an optimal move for the AI.
// The Vector3Int is really just a hack - the first coordinate is the
// id of the marble to move, and the second and third coordinates are the new position.
// if the first coordinate is negative, an error has occured.
// just like with EvaluateBoard(int), we maximize iff we are player1
public Vector3Int PickMove(int n, float priorWeight, ref bool doesWin)
{
Vector3Int ret = new Vector3Int(-1, -1, -1);
if (n == 0)
{
return(ret);
}
float optimalValue = curPlayer ? Mathf.NegativeInfinity : Mathf.Infinity;
Vector2Int[] myPieces = curPlayer ? player1Pieces : player2Pieces;
for (int i = 0; i < myPieces.Length; i++)
{
if (doesWin)
{
break;
}
Vector2Int piece = myPieces[i];
foreach (Vector2Int moveToPos in GetMoves(piece))
{
if (doesWin)
{
break;
}
VBoard newBoard = new VBoard(this);
newBoard.boardArr[piece.x, piece.y] = false;
newBoard.boardArr[moveToPos.x, moveToPos.y] = true;
(curPlayer ? newBoard.player1Pieces : newBoard.player2Pieces)[i] = moveToPos;
float newValue = newBoard.EvaluateBoard(n - 1, priorWeight, ref doesWin);
if (doesWin || (curPlayer ? (newValue > optimalValue) : (newValue < optimalValue)))
{
ret = new Vector3Int(i, moveToPos.x, moveToPos.y);
optimalValue = newValue;
}
}
}
Debug.Log("Optimal Value: " + optimalValue);
return(ret);
}
// use this to copy a VBoard, e.g. to test out certain moves:
public VBoard(VBoard original)
{
boardArr = new bool[width, height];
for (int i = 0; i < width; i++)
{
for (int j = 0; j < height; j++)
{
boardArr[i, j] = original.boardArr[i, j];
}
}
player1Pieces = new Vector2Int[original.player1Pieces.Length];
for (int i = 0; i < original.player1Pieces.Length; i++)
{
player1Pieces[i] = original.player1Pieces[i];
}
player2Pieces = new Vector2Int[original.player2Pieces.Length];
for (int i = 0; i < original.player2Pieces.Length; i++)
{
player2Pieces[i] = original.player2Pieces[i];
}
curPlayer = !original.curPlayer;
originalPlayer = original.originalPlayer;
}