/// <summary>
/// Checks the neiboring nodes
/// </summary>
/// <param name="inDirection">0-7, counter-clockwise starting at 0 degrees. (degrees = direction*45)</param>
private static void checkNeighborNode(Node inNode, int inDirection)
{
int nodeX = inNode.getX();
int nodeY = inNode.getY();
int checkX = nodeX;
int checkY = nodeY;
//Simple equation to set the distance multiplication
float distanceMultiplication = (inDirection % 2 == 0) ? 1.0f : 1.414f;
//Get the neighboring node's position
switch (inDirection)
{
case 0: checkX += 1; break;
case 1: checkX += 1; checkY -= 1; break;
case 2: checkY -= 1; break;
case 3: checkX -= 1; checkY -= 1; break;
case 4: checkX -= 1; break;
case 5: checkX -= 1; checkY += 1; break;
case 6: checkY += 1; break;
case 7: checkX += 1; checkY += 1; break;
}
//Only continue if the check position is still on the grid
if (checkX < gridWidth && checkX >= 0 && checkY < gridHeight && checkY >= 0)
{
//Now that we know it's still on the grid, get the node at that position
Node checkNode = getNodeAtPosition(checkX, checkY);
//Now only continue if the checkNode hasn't been circled and it's passable
if (!checkNode.getCircled() && checkNode.getValue() != IMPASSABLE_VALUE)
{
//Now calculate the various values for the check node
float currentNodeDistanceFromStart = inNode.getDistanceFromStart();
float toNodeDistance = checkNode.getValue() * distanceMultiplication;
float estimatedDistance = currentNodeDistanceFromStart + toNodeDistance + checkNode.getManhattanDistance();
//Update the estimated distance if it'll be smaller
//or if it hasn't been set yet
if (estimatedDistance < checkNode.getEstimatedDistance() || checkNode.getEstimatedDistance() < 0)
{
checkNode.setParent(inNode);
checkNode.setDistanceFromStart(currentNodeDistanceFromStart + toNodeDistance);
checkNode.setEstimatedDistance(estimatedDistance);
addToCheckList(checkNode);
}
}
}
}
//The base method for finding a path using A*
private static void findPath()
{
bool foundPath = false; //Whether or not a path has been found
Node startingNode = getNodeAtPosition(startX, startY); //The starting node
startingNode.setPath(true); //Tell the starting node it's on the final path
Node currentNode = startingNode; //It should start at the beginning
Node endingNode = getNodeAtPosition(endX, endY); //It should end at the end
while (!foundPath)
{
//Circle the current node
//and set the estimated distances for all nodes surrounding the current node
currentNode.setCircled(true);
for (int ii = 0; ii < 8; ii += 1)
{
checkNeighborNode(currentNode, ii);
}
Node nextNode;
//Get the next node if there is one in the check list
if (checkNodes.Count > 0)
{
nextNode = (Node)checkNodes[0];
}
else
{
nextNode = null;
}
//If the nextNode isn't null
if (nextNode != null)
{
//Remove it from the check list because we're using it now
checkNodes.RemoveAt(0);
//Circle it
nextNode.setCircled(true);
//Now set it as the current node
currentNode = nextNode;
//Now see if we've found the end
if (currentNode == endingNode)
{
Console.WriteLine("Found the end node");
Console.WriteLine("Total distance is: " + currentNode.getDistanceFromStart());
Console.WriteLine("The backtracking path is: ");
foundPath = true;
//We know for sure that we've found the end because the end node was in the top of the check list
}
}
else //We're all out of nodes to check and there isn't an end anywhere
{
throw new Exception("End not reachable");
}
}
//Now that the path is found, backtrack and build the path
Node backTrackCurrent = currentNode;
Console.WriteLine(backTrackCurrent.getSimpleString());
while (backTrackCurrent != startingNode)
{
backTrackCurrent.setPath(true);
backTrackCurrent = backTrackCurrent.getParent();
Console.WriteLine(backTrackCurrent.getSimpleString());
}
//Print the path if it can be printed
if (shouldPrintGrid)
{
printPath();
}
}