protected override bool TryPlacePiece(BoardState board, PieceDefinition piece, out PieceBitmap resultBitmap, out int resultX, out int resultY)
{
_evaluator.BeginEvaluation(board);
resultBitmap = null;
resultX = -1;
resultY = -1;
int bestScore = int.MinValue;
//Exhaustively place it and make new child nodes
for (var index = 0; index < piece.PossibleOrientations.Length; index++)
{
var bitmap = piece.PossibleOrientations[index];
var searchWidth = BoardState.Width - bitmap.Width + 1;
var searchHeight = BoardState.Height - bitmap.Height + 1;
//TODO? If this is the first piece, remove mirrors/rotations from the children
//if (isFirstPiece)
//{
// //TODO: This doesn't stop diagonal mirrors
// searchWidth = (BoardState.Width - bitmap.Width) / 2 + 1;
// searchHeight = (BoardState.Height - bitmap.Height) / 2 + 1;
//}
for (int x = 0; x < searchWidth; x++)
{
for (int y = 0; y < searchHeight; y++)
{
if (board.CanPlace(bitmap, x, y))
{
var clone = board;
clone.Place(bitmap, x, y);
var score = _evaluator.Evaluate(in clone, x, x + bitmap.Width, y, y + bitmap.Height);
if (score > bestScore)
{
resultBitmap = bitmap;
resultX = x;
resultY = y;
bestScore = score;
}
}
}
}
}
return(resultBitmap != null);
}
private void ExpandByPlacing(SearchNode root)
{
// This code mostly taken from WeightedTreeSearchPreplacer
_expandPlacingUtility.Clear();
var piece = root.State.PieceToPlace;
var isFirstPiece = root.State.PlayerBoardState[root.State.ActivePlayer].IsEmpty;
var board = root.State.PlayerBoardState[root.State.PieceToPlacePlayer];
var children = root.Children;
BoardEvaluator.BeginEvaluation(board);
//Exhaustively place it and make new child nodes
for (var index = 0; index < piece.PossibleOrientations.Length; index++)
{
var bitmap = piece.PossibleOrientations[index];
var searchWidth = BoardState.Width - bitmap.Width + 1;
var searchHeight = BoardState.Height - bitmap.Height + 1;
//If this is the first piece, remove mirrors/rotations from the children
if (isFirstPiece)
{
//TODO: This doesn't stop diagonal mirrors
searchWidth = (BoardState.Width - bitmap.Width) / 2 + 1;
searchHeight = (BoardState.Height - bitmap.Height) / 2 + 1;
}
for (int x = 0; x < searchWidth; x++)
{
for (int y = 0; y < searchHeight; y++)
{
if (board.CanPlace(bitmap, x, y))
{
//evaluate child nodes
var copy = board;
copy.Place(bitmap, x, y);
var utility = BoardEvaluator.Evaluate(in copy, x, x + bitmap.Width, y, y + bitmap.Height);
//Insertion sort us in to the children list
SearchNode child = null;
for (var i = 0; i < children.Count; i++)
{
//We should be here
if (utility > _expandPlacingUtility[i])
{
if (children.Count == MaxChildrenPerPiece)
{
//Children is already full, grab the last one and reuse it
child = children[MaxChildrenPerPiece - 1];
children.RemoveAt(MaxChildrenPerPiece - 1);
children.Insert(i, child);
_expandPlacingUtility.Insert(i, utility);
}
else
{
//Not full yet, just insert us here
child = NodePool.Value.Get();
children.Insert(i, child);
_expandPlacingUtility.Insert(i, utility);
}
break;
}
}
//Didn't find a place to put us, but children isn't full yet
if (child == null && children.Count < MaxChildrenPerPiece)
{
//Insert us last
child = NodePool.Value.Get();
children.Add(child);
_expandPlacingUtility.Add(utility);
}
//Populate the child
if (child != null)
{
child.PlaceBitmap = bitmap;
child.PlaceX = x;
child.PlaceY = y;
}
}
}
}
}
//Properly apply the placement in the children
for (var i = 0; i < children.Count; i++)
{
var c = children[i];
root.State.CloneTo(c.State);
c.State.PerformPlacePiece(c.PlaceBitmap, c.PlaceX, c.PlaceY);
c.Parent = root;
}
}