/// <summary>
/// Recursive method that floods the cave to discover holes in it, it fills a hole object that was given during the method invocation
/// </summary>
/// <param name="hole">The hole that is going to be filled</param>
private void Flood(ref bool[,] buffer, Bubble hole, int x, int y, bool target)
{
//if this cell is valid and it's empty
if (!(x < 0 || y < 0 || x >= buffer.GetLength(0) || y >= buffer.GetLength(0)) &&
buffer[x, y] != target)
{
//write fill it
buffer[x, y] = target;
//add its coordinate to the hole's list
hole.AddCell(x, y);
//reverberate to adjacent cells
Flood(ref buffer, hole, x + 1, y, target);
Flood(ref buffer, hole, x - 1, y, target);
Flood(ref buffer, hole, x, y + 1, target);
Flood(ref buffer, hole, x, y - 1, target);
}
}