// returns null if the system is considered "stable"
// on the other hand, if settling is necessary, returns the
// offending script after making one move towards a stable state
public CandyScript SettleStep()
{
KeyValuePair <Vector2Int, Vector2Int> move = FindStablizingMove();
if (move.Key.x == -1)
{
return(null);
}
candy_grid[move.Value.x][move.Value.y] = candy_grid[move.Key.x][move.Key.y];
candy_grid[move.Key.x][move.Key.y] = null;
CandyScript script = candy_grid[move.Value.x][move.Value.y];
float dx = new int[] { -1, 1 }[move.Value.y - move.Key.y + parity_map[move.Key.x]] *mainRadius;
float dy = PolyPieceGenerator.CalculateVStackDistance(6, mainRadius);
script.transform.position += new Vector3(dx, -dy, 0);
CandyScriptIndex id = candy_indexer[script];
id.row = move.Value.x;
id.column = move.Value.y;
return(script);
}
List <CandyScript> FetchNeighbours(CandyScript script)
{
CandyScriptIndex id = candy_indexer[script];
int x = id.column;
int y = id.row;
int p = parity_map[y];
List <Vector2Int> neighbour_indices = new List <Vector2Int>();
List <CandyScript> neighbours = new List <CandyScript>();
if (p == 1)
{
if (id.column != 0)
{
neighbour_indices.Add(new Vector2Int(x - 1, y));
neighbour_indices.Add(new Vector2Int(x - 1, y + 1));
neighbour_indices.Add(new Vector2Int(x - 1, y - 1));
}
if (id.column != cols)
{
neighbour_indices.Add(new Vector2Int(x + 1, y));
neighbour_indices.Add(new Vector2Int(x, y + 1));
neighbour_indices.Add(new Vector2Int(x, y - 1));
}
}
else
{
neighbour_indices.Add(new Vector2Int(x + 1, y + 1));
neighbour_indices.Add(new Vector2Int(x + 1, y - 1));
neighbour_indices.Add(new Vector2Int(x, y + 1));
neighbour_indices.Add(new Vector2Int(x, y - 1));
if (id.column != 0)
{
neighbour_indices.Add(new Vector2Int(x - 1, y));
}
if (id.column != cols - 1)
{
neighbour_indices.Add(new Vector2Int(x + 1, y));
}
}
foreach (Vector2Int ni in neighbour_indices)
{
Vector2Int gc = ConvertToGridIndices(ni);
CandyScript neighbour = SafeGridFetch(gc.x, gc.y);
if (neighbour != null)
{
neighbours.Add(neighbour);
}
}
return(neighbours);
}
// a candy is stable if either:
// - it's on the bottom row
// - it has two blocks supporting it
// - it is of odd parity and on an edge, with 1 block supporting it
bool IsStable(CandyScript c)
{
CandyScriptIndex id = candy_indexer[c];
return((id.row == candy_grid.Count - 1)
||
(parity_map[id.row] == 0 && // even parity
(SafeGridFetch(id.row + 1, id.column) != null && SafeGridFetch(id.row + 1, id.column + 1) != null)) // has 2 under it
||
(parity_map[id.row] == 1 && // odd parity
(SafeGridFetch(id.row + 1, id.column) != null && SafeGridFetch(id.row + 1, id.column - 1) != null) || // has 2 under it
((id.column == 0 || id.column == cols) && // is an edge piece
(SafeGridFetch(id.row + 1, id.column) != null || SafeGridFetch(id.row + 1, id.column - 1) != null))
)); // one supporting piece
}
