List <Vector2Int> GetCellsWithinRange()
{
cellPositionsInRange.Clear();
Vector2Int playerPosition = gameObject.GetComponent <GridPosition2d>().GridPosition;
Vector2Int offset = new Vector2Int();
int Range = movementPointsPerTurn;
for (int x = Range; x >= -Range; x--)
{
for (int y = Range; y >= -Range; y--)
{
if ((Mathf.Abs(x) + Mathf.Abs(y) > Range) == false)// Check if movement is out of player's range without diagonal movement.
{
offset.x = x;
offset.y = y;
if (GridUtilities.IsGridCellOccupied(ParentGrid, playerPosition + offset) == false)
{
cellPositionsInRange.Add(playerPosition + offset);
}
}
}
}
return(cellPositionsInRange);
}
// Not intended for use on each frame because of 'new' allocations.
bool MoveToGridPosition(Vector2Int gridPosition)
{
Debug.Assert(ParentGrid);
// As this is a 2D project, the cell Z position is irrelevant. The IsGridCellOccupied check is in 2D.
Vector3Int cellPosition3d = new Vector3Int(gridPosition.x, gridPosition.y, -3);
Vector3 worldCellPosition = ParentGrid.CellToWorld(cellPosition3d);
if (GridUtilities.IsGridCellOccupied(ParentGrid, gridPosition))
{
Debug.LogError("Attempted to move \"" + gameObject.name + "\" to occupied grid position: " + gridPosition.ToString());
return(false);
}
else
{
gameObject.transform.position = worldCellPosition - Vector3.forward;
return(true);
}
}
// Returns empty queue if there is no valid path. e.g. out of range or blocked.
// Uses breadth-first search as we have a small amount of cells and need to guarantee an optimal path.
// TODO: Consider caching a path to each cell that is queried, and returning it if it is present and valid.
// TODO: Consider moving the allocations out to the class level. This would make the class messier but decrease garbage accumulation.
public Queue <Vector2Int> GetPathToCell(Vector2Int targetCellPosition)
{
Queue <Vector2Int> pathQueue = new Queue <Vector2Int>();
Vector2Int playerPosition = GetComponent <GridPosition2d>().GridPosition;
// Position is out of range or blocked, early return.
if (cellPositionsInRange.Contains(targetCellPosition) == false)
{
return(pathQueue);
}
Queue <SearchCell> unsearchedCellQueue = new Queue <SearchCell>();
List <Vector2Int> searchedCells = new List <Vector2Int>();
Vector2Int searchDirection = new Vector2Int();
bool hasFoundPath = false;
SearchCell foundTargetCell = null;
// Start search at our current position.
unsearchedCellQueue.Enqueue(new SearchCell(playerPosition, null));
while (unsearchedCellQueue.Count > 0 && hasFoundPath == false)
{
SearchCell searchingCell = unsearchedCellQueue.Dequeue();
// Search in x direction
for (int x = -1; x <= 1; x++)
{
// Search in y direction
for (int y = -1; y <= 1; y++)
{
// This check disables searching diagonally.
if ((Mathf.Abs(x) + Mathf.Abs(y) > 1) == false)
{
searchDirection.x = x;
searchDirection.y = y;
SearchCell nextCell = new SearchCell(playerPosition + searchDirection, searchingCell)
{
Position = searchingCell.Position + searchDirection,
SearchedFrom = searchingCell
};
// Don't re-search searched cells.
if (searchedCells.Contains(searchingCell.Position + searchDirection) == false)
{
searchedCells.Add(nextCell.Position);
if (GridUtilities.IsGridCellOccupied(ParentGrid, nextCell.Position) == false)
{
unsearchedCellQueue.Enqueue(nextCell);
if (nextCell.Position == targetCellPosition)
{
foundTargetCell = nextCell;
hasFoundPath = true;
}
}
}
}
}
}
}
if (hasFoundPath)
{
while (foundTargetCell.Position != playerPosition)
{
pathQueue.Enqueue(foundTargetCell.Position);
foundTargetCell = foundTargetCell.SearchedFrom;
}
}
// Final range check.
if (pathQueue.Count > movementPointsPerTurn)
{
pathQueue.Clear();
}
return(pathQueue);
}