/// <summary>
/// The SimulationTimerEventHandler method is called when the simulation timer expires.
/// It updates the current state of the simulation.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void SimulationTimerEventHandler(object sender, EventArgs e)
{
try
{
if (SimulationState == SimulationState.Running)
{
MazeCell robotLocation = MazeCells.First(x => x.ContainsRobot); // Retrieve the current location of the robot.
int cellIndex = MazeCells.IndexOf(robotLocation); // Retrieve the index of the cell.
// Determine the indexes for the cell's neighbours.
int northNeighbourIndex = cellIndex - MazeWidthHeightCells;
int eastNeighbourIndex = cellIndex + 1;
int southNeighbourIndex = cellIndex + MazeWidthHeightCells;
int westNeighbourIndex = cellIndex - 1;
// Determine if the cell is on the north/east/south/west edge of the maze - certain neighbours must be ignored if the current cell is on an edge.
bool northEdge = cellIndex < MazeWidthHeightCells ? true : false;
bool eastEdge = ((cellIndex + 1) % MazeWidthHeightCells) == 0 ? true : false;
bool westEdge = (cellIndex % MazeWidthHeightCells) == 0 ? true : false;
bool southEdge = (cellIndex + MazeWidthHeightCells) >= (MazeWidthHeightCells * MazeWidthHeightCells) ? true : false;
// Retrieve the cell's neighbours.
MazeCell northCell = null;
MazeCell eastCell = null;
MazeCell southCell = null;
MazeCell westCell = null;
// North cell.
if (!northEdge && IsCellIndexValid(northNeighbourIndex))
{
northCell = MazeCells[northNeighbourIndex];
}
// East cell.
if (!eastEdge && IsCellIndexValid(eastNeighbourIndex))
{
eastCell = MazeCells[eastNeighbourIndex];
}
// South cell.
if (!southEdge && IsCellIndexValid(southNeighbourIndex))
{
southCell = MazeCells[southNeighbourIndex];
}
// West cell.
if (!westEdge && IsCellIndexValid(westNeighbourIndex))
{
westCell = MazeCells[westNeighbourIndex];
}
// Create a maze segment at the robot's current location.
MazeSegment mazeSegment = new MazeSegment(robotLocation, northCell, eastCell, southCell, westCell);
_robot.Move(mazeSegment); // Move the robot.
SimulationTime = SimulationTime.Add(TimeSpan.FromMilliseconds(Constants.DefaultStepIntervalMilliSeconds));
}
}
catch (Exception ex)
{
throw new Exception("Maze.SimulationTimerEventHandler(object sender, EventArgs e): " + ex.ToString());
}
}
/// <summary>
/// The Move method is called to move the robot.
/// The Trémaux's algorithm is used to control the robot.
/// https://en.wikipedia.org/wiki/Maze_solving_algorithm#Tr%C3%A9maux's_algorithm
/// </summary>
/// <param name="mazeSegment"></param>
public void Move(MazeSegment mazeSegment)
{
try
{
if (mazeSegment == null)
{
throw new Exception("maze segment can not be null.");
}
if (CurrentLocation == null)
{
// The robot is not in the maze - do nothing.
return;
}
// If the robot is NOT at a junction, mark the location.
if (mazeSegment.SegmentType != SegmentType.Junction)
{
CurrentLocation.MarkCell();
}
// If the robot is at a dead-end (except for the start of the maze), mark the location a second time.
if (mazeSegment.SegmentType == SegmentType.DeadEnd && CurrentLocation.CellRole != CellRole.Start)
{
CurrentLocation.MarkCell();
}
// Turn the robot, based on the type of maze segment.
CurrentDirection = mazeSegment.ChooseDirection(CurrentDirection);
// Attempt to move the robot forwards.
MazeCell newCurrentLocation = null;
if (CurrentDirection == Direction.North && mazeSegment.NorthCell.CellMark != CellMark.Twice)
{
newCurrentLocation = mazeSegment.NorthCell;
}
else if (CurrentDirection == Direction.East && mazeSegment.EastCell.CellMark != CellMark.Twice)
{
newCurrentLocation = mazeSegment.EastCell;
}
else if (CurrentDirection == Direction.South && mazeSegment.SouthCell.CellMark != CellMark.Twice)
{
newCurrentLocation = mazeSegment.SouthCell;
}
else if (CurrentDirection == Direction.West && mazeSegment.WestCell.CellMark != CellMark.Twice)
{
newCurrentLocation = mazeSegment.WestCell;
}
// Update the current location.
CurrentLocation.ContainsRobot = false;
CurrentLocation = newCurrentLocation != null ? newCurrentLocation : CurrentLocation;
CurrentLocation.ContainsRobot = true;
if (CurrentLocation.CellRole == CellRole.End)
{
OnReachedTheEnd?.Invoke(); // The robot has reached the end of the maze.
}
}
catch (Exception ex)
{
throw new Exception("Robot.Move(MazeSegment mazeSegment): " + ex.ToString());
}
}