/// <summary>
/// This is called when any grid space is clicked (see SetupGridSpaces())
/// </summary>
/// <param name="sender">The GridSpace which was clicked</param>
private void GridSpace_Click(object sender, EventArgs e)
{
if (_selectedGridSquare != null)
{
_selectedGridSquare.DeselectSpace();
}
_selectedGridSquare = (GridSpace)sender;
_selectedGridSquare.SelectSpace();
}
/// <summary>
/// Enforces the selected location (if it exists) to become "location2" (used as the ending node)
/// </summary>
private void btnSetLocation2_Click(object sender, EventArgs e)
{
if (_location2 != null)
{
_location2.ResetSpace();
}
if (_selectedGridSquare != null)
{
_location2 = _selectedGridSquare;
_selectedGridSquare.BackColor = Color.Red;
}
}
/// <summary>
/// Enforces the selected location (if it exists) to become "location1" (used as the starting node)
/// </summary>
private void btnSetLocation1_Click(object sender, EventArgs e)
{
if (_location1 != null)
{
_location1.ResetSpace();
}
if (_selectedGridSquare != null)
{
_selectedGridSquare.BackColor = Color.Blue;
_location1 = _selectedGridSquare;
}
}
/// <summary>
/// Clears all the existing MazeSquares and creates new ones
/// </summary>
private void SetupGridSpaces()
{
matrix = LoadGridMap("grid-map.txt");
pnlGridPanel.Controls.Clear(); // Clear the existing panel
// Calculate how many squares are required to fit the panel, given the square dimentions
int MazeSquaresHorizontal = pnlGridPanel.Width / GridSpace.GRID_SPACE_WIDTH;
int MazeSquaresVertical = pnlGridPanel.Height / GridSpace.GRID_SPACE_HEIGHT;
// Fill the panel with the number of required squares.
for (int i = 0; i < MazeSquaresVertical - 1; i++)
{
for (int j = 0; j < MazeSquaresHorizontal - 1; j++)
{
GridSpace newGridSpace = new GridSpace();
newGridSpace.BackColor = Color.White;
if (matrix[j, i] == "X") // In this implementation, "X" indicates an obstical for pathfinding purposes
{
newGridSpace.BackColor = Color.Black;
}
else if (matrix[j, i] == "G") // Just a demonstration of how we can flag other coloured gridspaces (that do nothing).
{
newGridSpace.BackColor = Color.Gold;
}
// These are the co-ordinates for the grid space
newGridSpace.GridX = j;
newGridSpace.GridY = i;
newGridSpace.Click += GridSpace_Click; // Used for determining which gridspace should be selected/deselected
newGridSpace.Location = new Point(j * newGridSpace.Width, i * newGridSpace.Height);
pnlGridPanel.Controls.Add(newGridSpace); // adds the gridspace to the panel
}
}
}
/// <summary>
/// An implementation of the A* pathfinding algorithm.
/// Source code adapted from https://stackoverflow.com/questions/2138642/how-to-implement-an-a-algorithm
/// </summary>
private GridSpace FindPathUsingAStar(string[,] matrix, int fromX, int fromY, int toX, int toY)
{
Dictionary <string, GridSpace> unvisitedNodes = new Dictionary <string, GridSpace>();
Dictionary <string, GridSpace> visitedNode = new Dictionary <string, GridSpace>();
// Find the required GridSpace object from the 2D panel
GridSpace startNode = GetGridSpaceGivenXandY(fromX, fromY);
string key = startNode.GridX.ToString() + startNode.GridX.ToString();
unvisitedNodes.Add(key, startNode);
// These are the values that will be added to the current GridSpace X and Y co-ordinates
// this will then mean we can find the co-ordinates of the current GridSpaces's neighbours
// IF YOU NEED DIAGONAL MOVES, THIS IS WHERE THEY WOULD BE ADDED (Add more neighbours to the list below, [1,1] [-1,-1], [1,-1] -[1,1] etc)
// (Added an example - see the IF statement immediately after these 5 statements)
List <KeyValuePair <int, int> > neighbours = new List <KeyValuePair <int, int> >();
neighbours.Add(new KeyValuePair <int, int>(-1, 0));
neighbours.Add(new KeyValuePair <int, int>(0, 1));
neighbours.Add(new KeyValuePair <int, int>(1, 0));
neighbours.Add(new KeyValuePair <int, int>(0, -1));
// Ok I added a demonstration...!
if (cbxDiagonalMode.Checked)
{
neighbours.Add(new KeyValuePair <int, int>(1, 1));
neighbours.Add(new KeyValuePair <int, int>(1, -1));
neighbours.Add(new KeyValuePair <int, int>(-1, 1));
neighbours.Add(new KeyValuePair <int, int>(-1, -1));
}
int maxX = matrix.GetLength(0) - 1;
int maxY = matrix.GetLength(1) - 1;
if (maxX == 0)
{
return(null);
}
while (true)
{
if (unvisitedNodes.Count == 0)
{
return(null);
}
KeyValuePair <string, GridSpace> current = FindSmallestWeighting(unvisitedNodes);
// This will exit the indefinite while loop once we find our destination GridSpace
if (current.Value.GridX == toX && current.Value.GridY == toY)
{
return(current.Value);
}
unvisitedNodes.Remove(current.Key);
visitedNode.Add(current.Key, current.Value);
// Check the weightings of all the neighbours to see which is best to visit next
foreach (KeyValuePair <int, int> plusXY in neighbours)
{
int nextX = current.Value.GridX + plusXY.Key;
int nextY = current.Value.GridY + plusXY.Value;
string nextWeighting = nextX.ToString() + nextY.ToString();
// The character 'X' indicates an obstacle
if (nextX < 0 || nextY < 0 || nextX >= maxX || nextY >= maxY || visitedNode.ContainsKey(nextWeighting) || matrix[nextX, nextY] == "X")
{
continue; // No need to visit this node - skip this iteration to check the next GridSpace
}
if (unvisitedNodes.ContainsKey(nextWeighting))
{
GridSpace currentSpace = unvisitedNodes[nextWeighting];
int from = Math.Abs(nextX - fromX) + Math.Abs(nextY - fromY);
if (from < currentSpace.FromWeighting)
{
currentSpace.FromWeighting = from;
currentSpace.SumWeight = currentSpace.FromWeighting + currentSpace.ToWeighting;
currentSpace.ParentSpace = current.Value;
}
}
else
{
// Find the required GridSpace object from the 2D panel
GridSpace currentSpace = GetGridSpaceGivenXandY(nextX, nextY);
// ABS as we don't want negative weights
currentSpace.FromWeighting = Math.Abs(nextX - fromX) + Math.Abs(nextY - fromY);
currentSpace.ToWeighting = Math.Abs(nextX - toX) + Math.Abs(nextY - toY);
currentSpace.SumWeight = currentSpace.FromWeighting + currentSpace.ToWeighting;
currentSpace.ParentSpace = current.Value;
unvisitedNodes.Add(nextWeighting, currentSpace);
}
}
}
}
/// <summary>
/// Helper method to get a specific GridSpace object from the form panel, given an x and y co-ordinate.
/// </summary>
public GridSpace GetGridSpaceGivenXandY(int x, int y)
{
GridSpace gridSpaceOnForm = (GridSpace)pnlGridPanel.GetChildAtPoint(new Point(x * GridSpace.GRID_SPACE_HEIGHT, y * GridSpace.GRID_SPACE_WIDTH));
return(gridSpaceOnForm);
}
