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This commit is contained in:
Lucas Morgan
2021-12-22 17:43:32 -06:00
parent aa4d5120e4
commit a2f3abb94e
14 changed files with 1096 additions and 212 deletions
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304
Shogi.Domain/StandardRules.cs
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@@ -4,6 +4,10 @@ namespace Shogi.Domain
{
internal class StandardRules
{
/// <param name="element">Guaranteed to be non-null.</param>
/// <param name="position"></param>
public delegate void Callback(Piece collider, Vector2 position);
private readonly ShogiBoardState board;
private Vector2 player1KingPosition;
private Vector2 player2KingPosition;
@@ -38,18 +42,20 @@ namespace Shogi.Domain
/// <param name="from">The position of the piece being moved expressed in board notation.</param>
/// <param name="to">The target position expressed in board notation.</param>
/// <returns>A <see cref="MoveResult" /> describing the success or failure of the simulation.</returns>
public MoveResult Move(string from, string to, bool isPromotion = false)
public MoveResult Move(Vector2 from, Vector2 to, bool isPromotion = false)
{
var fromPiece = board[from];
if (fromPiece == null)
{
return new MoveResult(false, $"Tile [{from}] is empty. There is no piece to move.");
}
if (fromPiece.Owner != board.WhoseTurn)
{
return new MoveResult(false, "Not allowed to move the opponents piece");
}
if (IsPathable(move.From.Value, move.To) == false)
if (IsPathable(from, to) == false)
{
return new MoveResult(false, $"Proposed move is not part of the move-set for piece {fromPiece.WhichPiece}.");
}
@@ -68,13 +74,11 @@ namespace Shogi.Domain
//Mutate the board.
if (isPromotion)
{
var fromVector = ShogiBoardState.FromBoardNotation(from);
var toVector = ShogiBoardState.FromBoardNotation(to);
if (board.WhoseTurn == WhichPlayer.Player1 && (toVector.Y > 5 || fromVector.Y > 5))
if (board.WhoseTurn == WhichPlayer.Player1 && (to.Y > 5 || from.Y > 5))
{
fromPiece.Promote();
}
else if (board.WhoseTurn == WhichPlayer.Player2 && (toVector.Y < 3 || fromVector.Y < 3))
else if (board.WhoseTurn == WhichPlayer.Player2 && (to.Y < 3 || from.Y < 3))
{
fromPiece.Promote();
}
@@ -85,17 +89,15 @@ namespace Shogi.Domain
{
if (fromPiece.Owner == WhichPlayer.Player1)
{
player1King.X = move.To.X;
player1King.Y = move.To.Y;
player1KingPosition = from;
}
else if (fromPiece.Owner == WhichPlayer.Player2)
{
player2King.X = move.To.X;
player2King.Y = move.To.Y;
player2KingPosition = from;
}
}
MoveHistory.Add(move);
return true;
//MoveHistory.Add(move);
return new MoveResult(true);
}
/// <summary>
@@ -104,30 +106,27 @@ namespace Shogi.Domain
/// <param name="pieceInHand"></param>
/// <param name="to">The target position expressed in board notation.</param>
/// <returns>A <see cref="MoveResult" /> describing the success or failure of the simulation.</returns>
public void Move(WhichPiece pieceInHand, string to)
public MoveResult Move(WhichPiece pieceInHand, Vector2 to)
{
var index = Hand.FindIndex(p => p.WhichPiece == move.PieceFromHand);
var index = board.Hand.FindIndex(p => p.WhichPiece == pieceInHand);
if (index == -1)
{
Error = $"{move.PieceFromHand} does not exist in the hand.";
return false;
return new MoveResult(false, $"{pieceInHand} does not exist in the hand.");
}
if (Board[move.To] != null)
if (board[to] != null)
{
Error = $"Illegal move - attempting to capture while playing a piece from the hand.";
return false;
return new MoveResult(false, $"Illegal move - attempting to capture while playing a piece from the hand.");
}
switch (move.PieceFromHand!.Value)
switch (pieceInHand)
{
case WhichPiece.Knight:
{
// Knight cannot be placed onto the farthest two ranks from the hand.
if ((WhoseTurn == WhichPlayer.Player1 && move.To.Y > 6)
|| (WhoseTurn == WhichPlayer.Player2 && move.To.Y < 2))
if ((board.WhoseTurn == WhichPlayer.Player1 && to.Y > 6)
|| (board.WhoseTurn == WhichPlayer.Player2 && to.Y < 2))
{
Error = $"Knight has no valid moves after placed.";
return false;
return new MoveResult(false, "Knight has no valid moves after placed.");
}
break;
}
@@ -135,134 +134,251 @@ namespace Shogi.Domain
case WhichPiece.Pawn:
{
// Lance and Pawn cannot be placed onto the farthest rank from the hand.
if ((WhoseTurn == WhichPlayer.Player1 && move.To.Y == 8)
|| (WhoseTurn == WhichPlayer.Player2 && move.To.Y == 0))
if ((board.WhoseTurn == WhichPlayer.Player1 && to.Y == 8)
|| (board.WhoseTurn == WhichPlayer.Player2 && to.Y == 0))
{
Error = $"{move.PieceFromHand} has no valid moves after placed.";
return false;
return new MoveResult(false, $"{pieceInHand} has no valid moves after placed.");
}
break;
}
}
// Mutate the board.
Board[move.To] = Hand[index];
Hand.RemoveAt(index);
MoveHistory.Add(move);
return true;
board[to] = board.Hand[index];
board.Hand.RemoveAt(index);
//MoveHistory.Add(move);
return new MoveResult(true);
}
private bool IsPathable(Vector2 from, Vector2 to)
{
var piece = Board[from];
var piece = board[from];
if (piece == null) return false;
var isObstructed = false;
var isPathable = pathFinder.PathTo(from, to, (other, position) =>
var isPathable = PathTo(from, to, (other, position) =>
{
if (other.Owner == piece.Owner) isObstructed = true;
});
return !isObstructed && isPathable;
}
private bool EvaluateCheckAfterMove(Move move, WhichPlayer WhichPerspective)
public bool EvaluateCheckAfterMove(WhichPiece pieceInHand, Vector2 to, WhichPlayer whichPlayer)
{
if (WhichPerspective == InCheck) return true; // If we already know the player is in check, don't bother.
if (whichPlayer == board.InCheck) return true; // If we already know the player is in check, don't bother.
var isCheck = false;
var kingPosition = WhichPerspective == WhichPlayer.Player1 ? player1King : player2King;
var kingPosition = whichPlayer == WhichPlayer.Player1 ? player1KingPosition : player2KingPosition;
// Check if the move put the king in check.
if (pathFinder.PathTo(move.To, kingPosition)) return true;
if (PathTo(to, kingPosition)) return true;
if (move.From.HasValue)
// TODO: Check for illegal move from hand. It is illegal to place from the hand such that you check-mate your opponent.
// Go read the shogi rules to be sure this is true.
return isCheck;
}
public bool EvaluateCheckAfterMove(Vector2 from, Vector2 to, WhichPlayer whichPlayer)
{
if (whichPlayer == board.InCheck) return true; // If we already know the player is in check, don't bother.
var isCheck = false;
var kingPosition = whichPlayer == WhichPlayer.Player1 ? player1KingPosition : player2KingPosition;
// Check if the move put the king in check.
if (PathTo(to, kingPosition)) return true;
// Get line equation from king through the now-unoccupied location.
var direction = Vector2.Subtract(kingPosition, from);
var slope = Math.Abs(direction.Y / direction.X);
// If absolute slope is 45°, look for a bishop along the line.
// If absolute slope is 0° or 90°, look for a rook along the line.
// if absolute slope is 0°, look for lance along the line.
if (float.IsInfinity(slope))
{
// Get line equation from king through the now-unoccupied location.
var direction = Vector2.Subtract(kingPosition, move.From!.Value);
var slope = Math.Abs(direction.Y / direction.X);
// If absolute slope is 45°, look for a bishop along the line.
// If absolute slope is 0° or 90°, look for a rook along the line.
// if absolute slope is 0°, look for lance along the line.
if (float.IsInfinity(slope))
// if slope of the move is also infinity...can skip this?
LinePathTo(kingPosition, direction, (piece, position) =>
{
// if slope of the move is also infinity...can skip this?
pathFinder.LinePathTo(kingPosition, direction, (piece, position) =>
if (piece.Owner != whichPlayer)
{
if (piece.Owner != WhichPerspective)
switch (piece.WhichPiece)
{
switch (piece.WhichPiece)
{
case WhichPiece.Rook:
isCheck = true;
break;
case WhichPiece.Lance:
if (!piece.IsPromoted) isCheck = true;
break;
}
case WhichPiece.Rook:
isCheck = true;
break;
case WhichPiece.Lance:
if (!piece.IsPromoted) isCheck = true;
break;
}
});
}
else if (slope == 1)
{
pathFinder.LinePathTo(kingPosition, direction, (piece, position) =>
{
if (piece.Owner != WhichPerspective && piece.WhichPiece == WhichPiece.Bishop)
{
isCheck = true;
}
});
}
else if (slope == 0)
{
pathFinder.LinePathTo(kingPosition, direction, (piece, position) =>
{
if (piece.Owner != WhichPerspective && piece.WhichPiece == WhichPiece.Rook)
{
isCheck = true;
}
});
}
}
});
}
else
else if (slope == 1)
{
// TODO: Check for illegal move from hand. It is illegal to place from the hand such that you check-mate your opponent.
// Go read the shogi rules to be sure this is true.
LinePathTo(kingPosition, direction, (piece, position) =>
{
if (piece.Owner != whichPlayer && piece.WhichPiece == WhichPiece.Bishop)
{
isCheck = true;
}
});
}
else if (slope == 0)
{
LinePathTo(kingPosition, direction, (piece, position) =>
{
if (piece.Owner != whichPlayer && piece.WhichPiece == WhichPiece.Rook)
{
isCheck = true;
}
});
}
return isCheck;
}
private bool EvaluateCheckmate()
public bool EvaluateCheckmate()
{
if (!InCheck.HasValue) return false;
if (!board.InCheck.HasValue) return false;
// Assume true and try to disprove.
var isCheckmate = true;
Board.ForEachNotNull((piece, from) => // For each piece...
board.ForEachNotNull((piece, from) => // For each piece...
{
// Short circuit
if (!isCheckmate) return;
if (piece.Owner == InCheck) // ...owned by the player in check...
if (piece.Owner == board.InCheck) // ...owned by the player in check...
{
// ...evaluate if any move gets the player out of check.
pathFinder.PathEvery(from, (other, position) =>
PathEvery(from, (other, position) =>
{
var simulationBoard = new Shogi(this);
var moveToTry = new Move(from, position);
var moveSuccess = simulationBoard.TryMove(moveToTry);
if (moveSuccess)
var simulationBoard = new StandardRules(new ShogiBoardState(board));
var simulationResult = simulationBoard.Move(from, position, false);
if (simulationResult.Success)
{
if (!EvaluateCheckAfterMove(moveToTry, InCheck.Value))
if (!EvaluateCheckAfterMove(from, position, board.InCheck.Value))
{
isCheckmate = false;
}
}
});
}
// TODO: Assert that a player could not place a piece from their hand to avoid check.
});
return isCheckmate;
}
/// <summary>
/// Navigate the collection such that each "step" is always towards the destination, respecting the Paths available to the element at origin.
/// </summary>
/// <param name="element">The pathing element.</param>
/// <param name="origin">The starting location.</param>
/// <param name="destination">The destination.</param>
/// <param name="callback">Do cool stuff here.</param>
/// <returns>True if the element reached the destination.</returns>
public bool PathTo(Vector2 origin, Vector2 destination, Callback? callback = null)
{
if (destination.X > 8 || destination.Y > 8 || destination.X < 0 || destination.Y < 0)
{
return false;
}
var piece = board[origin];
if (piece == null) return false;
var path = FindDirectionTowardsDestination(GetMoveSet(piece.WhichPiece).GetMoves(piece.IsUpsideDown), origin, destination);
if (!IsPathable(origin, destination))
{
// Assumption: if a single best-choice step towards the destination cannot happen, no pathing can happen.
return false;
}
var shouldPath = true;
var next = origin;
while (shouldPath && next != destination)
{
next = Vector2.Add(next, path.Direction);
var collider = board[next];
if (collider != null)
{
callback?.Invoke(collider, next);
shouldPath = false;
}
else if (path.Distance == Distance.OneStep)
{
shouldPath = false;
}
}
return next == destination;
}
public void PathEvery(Vector2 from, Callback callback)
{
var piece = board[from];
if (piece == null)
{
return;
}
foreach (var path in GetMoveSet(piece.WhichPiece).GetMoves(piece.IsUpsideDown))
{
var shouldPath = true;
var next = Vector2.Add(from, path.Direction); ;
while (shouldPath && next.X < 8 && next.Y < 8 && next.X >= 0 && next.Y >= 0)
{
var collider = board[(int)next.Y, (int)next.X];
if (collider != null)
{
callback(collider, next);
shouldPath = false;
}
if (path.Distance == Distance.OneStep)
{
shouldPath = false;
}
next = Vector2.Add(next, path.Direction);
}
}
}
/// <summary>
/// Path the line from origin to destination, ignoring any Paths defined by the element at origin.
/// </summary>
public void LinePathTo(Vector2 origin, Vector2 direction, Callback callback)
{
direction = Vector2.Normalize(direction);
var next = Vector2.Add(origin, direction);
while (next.X >= 0 && next.X < 8 && next.Y >= 0 && next.Y < 8)
{
var element = board[next];
if (element != null) callback(element, next);
next = Vector2.Add(next, direction);
}
}
public static Move FindDirectionTowardsDestination(ICollection<Move> paths, Vector2 origin, Vector2 destination) =>
paths.Aggregate((a, b) =>
{
var distanceA = Vector2.Distance(destination, Vector2.Add(origin, a.Direction));
var distanceB = Vector2.Distance(destination, Vector2.Add(origin, b.Direction));
return distanceA < distanceB ? a : b;
});
public static MoveSet GetMoveSet(WhichPiece whichPiece)
{
return whichPiece switch
{
WhichPiece.King => MoveSet.King,
WhichPiece.GoldGeneral => MoveSet.GoldGeneral,
WhichPiece.SilverGeneral => MoveSet.SilverGeneral,
WhichPiece.Bishop => MoveSet.Bishop,
WhichPiece.Rook => MoveSet.Rook,
WhichPiece.Knight => MoveSet.Knight,
WhichPiece.Lance => MoveSet.Lance,
WhichPiece.Pawn => MoveSet.Pawn,
_ => throw new ArgumentException($"{nameof(WhichPiece)} not recognized."),
};
}
}
}