/// <summary>
/// The StartFireAtPoint method is called to start a fire at a specific point in the forest.
/// </summary>
/// <param name="point"></param>
/// <param name="forestWidthPixels"></param>
/// <param name="forestHeightPixels"></param>
public void StartFireAtPoint(Point point, double forestWidthPixels, double forestHeightPixels)
{
try
{
if (point != null && forestWidthPixels > 0 && forestHeightPixels > 0)
{
// Retrieve the x/y coordinates in pixels.
double xPositionPixels = point.X;
double yPositionPixels = point.Y;
// Convert the x/y coordinates from pixels to cells.
int xPosition = (int)((xPositionPixels / forestWidthPixels) * Constants.ForestWidth);
int yPosition = (int)((yPositionPixels / forestHeightPixels) * Constants.ForestHeight);
// Determine the cell index from the x/y coordinates.
int cellIndex = xPosition + (yPosition * Constants.ForestWidth);
// Retrieve the forest cell and set it to burning.
if (IsCellIndexValid(cellIndex))
{
ForestCell forestCell = _forestCells.ElementAt(cellIndex);
if (forestCell.CellState == CellState.Tree)
{
forestCell.CellState = CellState.Burning;
}
}
}
}
catch (Exception ex)
{
throw new Exception("Forest.StartFireAtPoint(Point point, double forestWidthPixels, double forestHeightPixels): " + ex.ToString());
}
}
/// <summary>
/// Create a forest cell from an existing forest cell.
/// </summary>
/// <param name="forestCell"></param>
public ForestCell(ForestCell forestCell)
{
try
{
if (forestCell == null)
{
throw new Exception("forestCell can not be null");
}
_cellState = forestCell.CellState;
}
catch (Exception ex)
{
throw new Exception("ForestCell(ForestCell forestCell): " + ex.ToString());
}
}
/// <summary>
/// The UpdateForest method is called to update the forest.
/// An empty cell may become a tree cell, as per the regrowth probability.
/// A burning cell becomes an empty cell.
/// A tree cell becomes a burning cell, if any of its neighbours are burning.
/// A tree cell may become a burning cell, even with no burning neighbours, as per the lightning probability.
/// </summary>
private async Task UpdateForest()
{
try
{
await Task.Run(() =>
{
lock (_updateLock)
{
ObservableCollection <ForestCell> updatedForest = new ObservableCollection <ForestCell>(); // The updated forest.
// Update the forest cells, one cell at a time.
foreach (ForestCell forestCell in _forestCells)
{
ForestCell updatedForestCell = new ForestCell(forestCell); // Make a copy of the current forest cell.
// Update the forest cell.
if (forestCell.CellState == CellState.Empty)
{
// If the cell is empty, apply regrowth.
updatedForestCell.CellState = ApplyRegrowth() ? CellState.Tree : updatedForestCell.CellState;
}
else if (forestCell.CellState == CellState.Tree)
{
// If the cell is a tree, check for any burning neighbours.
int cellIndex = _forestCells.IndexOf(forestCell); // Retrieve the index of the tree cell.
// Determine the indexes for all of the neighbours.
int topNeighbourIndex = cellIndex - Constants.ForestWidth;
int topRightNeighbourIndex = cellIndex - Constants.ForestWidth + 1;
int rightNeighbourIndex = cellIndex + 1;
int bottomRightNeighbourIndex = cellIndex + Constants.ForestWidth + 1;
int bottomNeighbourIndex = cellIndex + Constants.ForestWidth;
int bottomLeftNeighbourIndex = cellIndex + Constants.ForestWidth - 1;
int leftNeighbourIndex = cellIndex - 1;
int topLeftNeighbourIndex = cellIndex - Constants.ForestWidth - 1;
// Determine if the cell is on the top/right/bottom/left edge of the forest - certain neighbours must be ignored if a cell is on an edge.
bool topEdge = cellIndex < Constants.ForestWidth ? true : false;
bool rightEdge = ((cellIndex + 1) % Constants.ForestWidth) == 0 ? true : false;
bool leftEdge = (cellIndex % Constants.ForestWidth) == 0 ? true : false;
bool bottomEdge = (cellIndex + Constants.ForestWidth) >= (Constants.ForestWidth *Constants.ForestHeight) ? true : false;
// Check each neighbour.
if (!topEdge && updatedForestCell.CellState != CellState.Burning && IsCellBurning(topNeighbourIndex))
{
updatedForestCell.CellState = CellState.Burning;
}
if (!rightEdge && updatedForestCell.CellState != CellState.Burning && IsCellBurning(topRightNeighbourIndex))
{
updatedForestCell.CellState = CellState.Burning;
}
if (!rightEdge && updatedForestCell.CellState != CellState.Burning && IsCellBurning(rightNeighbourIndex))
{
updatedForestCell.CellState = CellState.Burning;
}
if (!rightEdge && updatedForestCell.CellState != CellState.Burning && IsCellBurning(bottomRightNeighbourIndex))
{
updatedForestCell.CellState = CellState.Burning;
}
if (!bottomEdge && updatedForestCell.CellState != CellState.Burning && IsCellBurning(bottomNeighbourIndex))
{
updatedForestCell.CellState = CellState.Burning;
}
if (!leftEdge && updatedForestCell.CellState != CellState.Burning && IsCellBurning(bottomLeftNeighbourIndex))
{
updatedForestCell.CellState = CellState.Burning;
}
if (!leftEdge && updatedForestCell.CellState != CellState.Burning && IsCellBurning(leftNeighbourIndex))
{
updatedForestCell.CellState = CellState.Burning;
}
if (!leftEdge && updatedForestCell.CellState != CellState.Burning && IsCellBurning(topLeftNeighbourIndex))
{
updatedForestCell.CellState = CellState.Burning;
}
// If the cell is still a tree, apply a lighting strike.
if (updatedForestCell.CellState == CellState.Tree)
{
updatedForestCell.CellState = ApplyLightningStrike() ? CellState.Burning : updatedForestCell.CellState;
}
}
else if (forestCell.CellState == CellState.Burning)
{
// If the cell is burning, it becomes an empty cell.
updatedForestCell.CellState = CellState.Empty;
}
updatedForest.Add(updatedForestCell); // Add the updated forest cell to the updated forest.
}
// Update the forest.
if (updatedForest.Count == _forestCells.Count)
{
foreach (ForestCell forestCell in _forestCells)
{
CellState updatedCellState = updatedForest.ElementAt(_forestCells.IndexOf(forestCell)).CellState;
if (updatedCellState != forestCell.CellState)
{
forestCell.CellState = updatedCellState;
}
}
}
}
});
}
catch (Exception ex)
{
throw new Exception("Forest.UpdateForest(): " + ex.ToString());
}
}
