/* This will find a path from To - From if it exists
* If it succeeds it will return a list of Waypoints, tile by tile, which if followed will lead to the destination
* If it fails the list will be empty
* Any non null entry in the array will block the movement
* if Debug is true , this will draw DebugDots on the path
*/
public List <Waypoint> Find(Waypoint vFrom, Waypoint vTo, GameObject[,] vMap, bool vDebug = false)
{
mOpen = new List <Node> (); //Keep a list of open paths to explore
mClosed = new List <Node> (); //List of closed paths, I.E. ones which have been explored
mMap = vMap; //Keep a pointer to the map of blocking tiles
mDestination = new Node(vTo); //Make a destination node, so we can check we have arrived
mWidth = mMap.GetLength(0); //Cache size of map to make bounds check faster
mHeight = mMap.GetLength(1);
mNeighbours = SetNeighbours(); //Cache list of relative neighbours, only happens first time as its static
Node tCurrent = new Node(vFrom); //Add starting node to the Open list
mOpen.Add(tCurrent); //Add starting point
mDebug = vDebug; //Should we draw debug circles
if (mDebug)
{
DebugHelper.DebugDot(vFrom.X, vFrom.Y, Color.yellow, mSlowDotFade); //Show starting position
DebugHelper.DebugDot(vTo.X, vTo.Y, Color.cyan, mSlowDotFade); //Show finish position
}
return(CalculatePath()); //Run A*
}
public List <Waypoint> CalculatePath() //Main A* routine, makes a path to the target
{
bool Quit = false; //Used to exit infinite loop when debugging, set to true to stop Unity locking up
List <Waypoint> tPath = new List <Waypoint>(); //List for storing found path
do
{
Node tShortNode = FindShortOpen(); //Find current open path with shortest F
mOpen.Remove(tShortNode); //Move it to closed list
mClosed.Add(tShortNode); //
if (mDebug) //Draw a Dot to show current path progress
{
DebugHelper.DebugDot(tShortNode.X, tShortNode.Y, Color.gray, mFastDotFade);
}
Node tAtDestination = IsInClosed(mDestination); //Check if we have reached the destination
if (tAtDestination != null) //If the destination is in closed list we are there
{
Node tNext;
do //Construct list of waypoints for caller
{
tNext = tAtDestination.Parent; //Follow links from destination to start (reverse order)
if (tNext != null) //We dont need to include start position and when we have reached it parent will be null and list is complete
{
Waypoint tWayPoint = new Waypoint(tAtDestination); //Add waypoint from current Destination as we walk the list back to the origin
if (mDebug) //Show Path if debugging
{
DebugHelper.DebugDot(tWayPoint.X, tWayPoint.Y, Color.red, mSlowDotFade);
}
tPath.Insert(0, tWayPoint); //Add waypoint, by adding at start of list we are reversing the Node list, which is what we want as its back to front when generated
//ie. the nodes go from the end point to the start
tAtDestination = tNext; //Following the parent reference will take us back to the start
}
else
{
break; //Done, we can leave the loop
}
} while (true);
mOpen = null; //Release resources
mClosed = null;
mDestination = null;
return(tPath); //Send Path to caller
}
List <Node> tWalkableNodes = Walkable(tShortNode); //If we are not there yet, find all walkable squares centered around current position
foreach (Node tCurrent in tWalkableNodes)
{
if (IsInClosed(tCurrent) != null) //If we have this square in closed list already, we can skip it
{
continue;
}
Node tOpen = IsInOpen(tCurrent); //If its in open list get it
if (tOpen == null)
{
mOpen.Add(tCurrent); //Add to new open list if its not already there
}
else
{
tOpen.UpdateIfCloser(tCurrent); //If we have it check if this one would give a better F Score (by having a lower G), if so replace & reparent
}
}
} while (mOpen.Count > 0 && !Quit); //Keep going while we have open destinations, if there are none, it his means the path does not exist, also allow debugger to exit by setting Quit true, stops Unity Hanging
return(tPath); //If we get here we are going to return an empty path, as success exit is higher up
}
