public void Execute()
{
var(startX, startY) = GridUtils.GetCoordinates(_startIndex, _gridRows);
int bestDelta = 0, bestIndex = -1;
for (int x = 1; x < _gridCols - 1; x++)
{
for (int y = 1; y < _gridRows - 1; y++)
{
var index = GridUtils.GetIndex(x, y, _gridRows);
if (_floodState[index] != GridStateConstants.FLOODED)
{
continue;
}
var delta = Math.Abs(x - startX) + Math.Abs(y - startY);
if (delta <= bestDelta)
{
continue;
}
bestDelta = delta;
bestIndex = index;
}
}
if (bestIndex == -1)
{
throw new IndexOutOfRangeException();
}
_gridState[bestIndex] = GridStateConstants.EXIT;
}
private void FloodFill()
{
// we use byte.MaxValue as an 'unset' state value
for (int i = 0; i < _cellStack.Length; i++)
{
_cellStack[i] = GridStateConstants.UNSET;
}
for (int i = 0; i < _floodState.Length; i++)
{
_floodState[i] = GridStateConstants.UNSET;
}
// Add starting cell - must be free
Push(_startIndex);
do
{
var index = Pop();
if (index == GridStateConstants.UNSET)
{
break;
}
_floodState[index] = GridStateConstants.FLOODED;
var(x, y) = GridUtils.GetCoordinates(index, _rows);
if (GridUtils.HasOutOfBoundsNeighbour(x, y, _rows, _cols))
{
continue;
}
// Left
var left = GridUtils.GetIndex(x - 1, y, _rows);
if (_gridState[left] == GridStateConstants.FREE && _floodState[left] != GridStateConstants.FLOODED)
{
Push(left);
}
// Right
var right = GridUtils.GetIndex(x + 1, y, _rows);
if (_gridState[right] == GridStateConstants.FREE && _floodState[right] != GridStateConstants.FLOODED)
{
Push(right);
}
var up = GridUtils.GetIndex(x, y + 1, _rows);
if (_gridState[up] == GridStateConstants.FREE && _floodState[up] != GridStateConstants.FLOODED)
{
Push(up);
}
var down = GridUtils.GetIndex(x, y - 1, _rows);
if (_gridState[down] == GridStateConstants.FREE && _floodState[down] != GridStateConstants.FLOODED)
{
Push(down);
}
} while (_stackCount > 0);
}
private void FloodGate()
{
for (var index = _cols; index < _gridState.Length - _cols; index++)
{
if (_floodState[index] != GridStateConstants.FLOODED)
{
continue;
}
var(x, y) = GridUtils.GetCoordinates(index, _rows);
var topLeft = GridUtils.GetIndex(x - 1, y + 1, _rows);
var topRight = GridUtils.GetIndex(x + 1, y - 1, _rows);
var botLeft = GridUtils.GetIndex(x - 1, y - 1, _rows);
var botRight = GridUtils.GetIndex(x + 1, y - 1, _rows);
int targetIndex;
if (_gridState[topLeft] == GridStateConstants.FREE || _gridState[botLeft] == GridStateConstants.FREE)
{
targetIndex = x - 1; // left cell
}
else if (_gridState[topRight] == GridStateConstants.FREE || _gridState[botRight] == GridStateConstants.FREE)
{
targetIndex = x + 1; // right cell
}
else
{
continue;
}
var(targetX, targetY) = GridUtils.GetCoordinates(targetIndex, _rows);
if (GridUtils.HasOutOfBoundsNeighbour(targetX, targetY, _rows, _cols))
{
continue;
}
//UnityEngine.Debug.Log($"index: {index} has {freeNeighbours} free neighbours, delta: {freeNeighbourIdx - index}");
_gridState[targetIndex] = GridStateConstants.FREE;
}
}