private static void CheckBox(Level level, Array2D<int> noBoxMap, Array2D<bool> simpleDeadlockMap, Coordinate2D coord)
{
// Check whether we've visited this square before.
if (noBoxMap[coord] == 0)
{
return;
}
// This square is not a no-box square.
noBoxMap[coord] = 0;
// Recursively check for other squares that are not no-box squares.
foreach (Direction direction in Direction.Directions)
{
// Get parallel and perpendicular offsets.
Coordinate2D parallel = direction;
Coordinate2D perpendicular = Coordinate2D.Transpose(parallel);
// Check whether we can move the box to the new position.
if (level.IsFloor(coord - parallel) && level.IsFloor(coord + parallel))
{
Coordinate2D oldBoxCoord = coord;
Coordinate2D newBoxCoord = coord + parallel;
// Check for the special case of no influence pushes that lead to deadlocks.
bool specialCase = false;
while (level.IsWall(oldBoxCoord + perpendicular) &&
level.IsWall(oldBoxCoord - perpendicular) &&
((level.IsWall(newBoxCoord + perpendicular) &&
level.IsWallOrEmpty(newBoxCoord - perpendicular)) ||
(level.IsWallOrEmpty(newBoxCoord + perpendicular) &&
level.IsWall(newBoxCoord - perpendicular))))
{
if (level.IsTarget(newBoxCoord))
{
break;
}
if (!level.IsFloor(newBoxCoord) || simpleDeadlockMap[newBoxCoord])
{
specialCase = true;
break;
}
oldBoxCoord += parallel;
newBoxCoord += parallel;
}
// Otherwise recursively check for more squares.
if (!specialCase)
{
CheckBox(level, noBoxMap, simpleDeadlockMap, coord + parallel);
}
}
}
}
