private Positions FindFarthestPosition(CellPosition cell, Vector vector)
{
CellPosition previous;
// Progress towards the vector direction until an obstacle is found
do
{
previous = cell;
cell = new CellPosition(previous.X + vector.X, previous.Y + vector.Y);
} while (_grid.WithinBounds(cell) &&
_grid.CellAvailable(cell));
return(new Positions(
previous,
cell // Used to check if a merge is required
));
}
public bool WithinBounds(CellPosition position)
{
return(WithinBounds(position.X, position.Y));
}
public GameTile CellContent(CellPosition position)
{
return(CellContent(position.X, position.Y));
}
public bool IsEqual(CellPosition pos)
{
return(X == pos.X && Y == pos.Y);
}
private bool CellOccupied(CellPosition position)
{
return(null != Cells[position.X, position.Y]);
}
// Check if the specified cell is taken
public bool CellAvailable(CellPosition position)
{
return(!CellOccupied(position));
}
public Positions(CellPosition farthest, CellPosition next)
{
Farthest = farthest;
Next = next;
}
private void MoveTile(GameTile tile, CellPosition cell)
{
_grid.Cells[tile.Position.X, tile.Position.Y] = null;
_grid.Cells[cell.X, cell.Y] = tile;
tile.UpdatePosition(cell);
}
// Move tiles on the grid in the specified direction
private void InternalMove(MoveDirection direction)
{
if (IsGameTerminated())
{
return; // Don't do anything if the game's over
}
GameTile tile = null;
var vector = GetVector(direction);
var traversals = new Traversals(_size, vector);
var moved = false;
// Save the current tile positions and remove merger information
PrepareTiles();
// Traverse the grid in the right direction and move tiles
foreach (var x in traversals.Xs)
{
foreach (var y in traversals.Ys)
{
var cell = new CellPosition(x, y);
tile = _grid.CellContent(cell);
if (null != tile)
{
var positions = FindFarthestPosition(cell, vector);
var next = _grid.CellContent(positions.Next);
// Only one merger per row traversal?
if (null != next && next.Value == tile.Value && (null == next.MergedFrom))
{
var merged = new GameTile(positions.Next, tile.Value * 2);
merged.MergedFrom = new MergeTile(tile.Position, next.Position);
_grid.InsertTile(merged);
_grid.RemoveTile(tile);
// Converge the two tiles' positions
tile.UpdatePosition(positions.Next);
// Update the score
Score += merged.Value;
// The mighty 2048 tile
if (merged.Value == _winingTileValue)
{
Won = true;
}
}
else
{
MoveTile(tile, positions.Farthest);
}
if (!cell.IsEqual(tile.Position))
{
moved = true; // The tile moved from its original cell!
}
}
}
}
if (moved)
{
AddRandomTile();
if (!MovesAvailable())
{
Over = true; // Game over!
}
Actuate();
}
}
