public int recalculateAssociateCost() {
int temp = 0;
if (associateCost != 0) temp = parent.recalculateAssociateCost();
return temp;
}
/** @see PathFinder#findPath(Mover, int, int, int, int) */
public Path findPath(int sx, int sy, int tx, int ty) {
System.out.println("Find Path Called");
// easy first check, if the destination is blocked, we can't get there
if (blocked(tx, ty)) {
System.out.println("Pathfinder Target Is Blocked");
}
// initial state for A*. The closed group is empty. Only the starting
// tile is in the open list and it's cost is zero, i.e. we're already there
nodes[sx][sy].cost = 0;
nodes[sx][sy].depth = 0;
closed.clear();
open.clear();
open.add(nodes[sx][sy]);
nodes[tx][ty].parent = null;
// while we haven't found the goal and haven't exceeded our max search epth
int maxDepth = 0;
while ((maxDepth < maxSearchDistance) && (open.size() != 0)) {
// pull out the first node in our open list, this is determined to
// be the most likely to be the next step based on our heuristic
Node current = getFirstInOpen();
if (current == nodes[tx][ty]) {
break;
}
removeFromOpen(current);
addToClosed(current);
// search through all the neighbours of the current node evaluating
// them as next steps
for (int x = -1; x < 2; x++) {
for (int y = -1; y < 2; y++) {
// not a neighbour, its the current tile
if ((x == 0) && (y == 0)) {
continue;
}
// if we're not allowing diaganol movement then only
// one of x or y can be set
if (!allowDiagMovement) {
if ((x != 0) && (y != 0)) {
continue;
}
}
// determine the location of the neighbour and evaluate it
int xp = x + current.x;
int yp = y + current.y;
if (isValidLocation(sx, sy, xp, yp)) {
// the cost to get to this node is cost the current plus the movement
// cost to reach this node. Note that the heursitic value is only used
// in the sorted open list
float nextStepCost = current.cost + getMovementCost(current.x, current.y, xp, yp);
Node neighbour = nodes[xp][yp];
pathFinderVisited(xp, yp);
// if the new cost we've determined for this node is lower than
// it has been previously makes sure the node hasn't been discarded. We've
// determined that there might have been a better path to get to
// this node so it needs to be re-evaluated
if (nextStepCost < neighbour.cost) {
if (inOpenList(neighbour)) {
removeFromOpen(neighbour);
}
if (inClosedList(neighbour)) {
removeFromClosed(neighbour);
}
}
// if the node hasn't already been processed and discarded then
// reset it's cost to our current cost and add it as a next possible
// step (i.e. to the open list)
if (!inOpenList(neighbour) && !(inClosedList(neighbour))) {
neighbour.cost = nextStepCost;
neighbour.heuristic = getCost(xp, yp, tx, ty);
maxDepth = Math.max(maxDepth, neighbour.setParent(current));
addToOpen(neighbour);
}
}
}
}
}
// since we've got an empty open list or we've run out of search
// there was no path. Just return null
if (nodes[tx][ty].parent == null) {
return null;
}
// At this point we've definitely found a path so we can uses the parent
// references of the nodes to find out way from the target location back
// to the start recording the nodes on the way.
Path path = new Path();
Node target = nodes[tx][ty];
while (target != nodes[sx][sy]) {
path.prependStep(target.x, target.y);
target = target.parent;
}
path.prependStep(sx, sy);
// thats it, we have our path
if (path == null) System.out.println("Null Path Returned From Pathfinder");
return path;
}
