/*
* Helper for A*
* Finds passable neighbors for any tile
*/
private static Set<Node> passableNeighbors(
Node[][] board, Node t, Master m, Iterable<? extends Sprite> spriteSet) {
Set<Node> neighs = new HashSet<Node>();
Vec2i loc = t.getCoords();
for (int i = -1; i < 2; i++) {
for (int j = -1; j < 2; j++) {
if (j == i || (j != 0 && i != 0)) {
continue;
} else if (loc.x + i >= 0
&& loc.x + i < board[0].length
&& loc.y + j >= 0
&& loc.y + j < board.length
&& !board[(loc.x + i)][(loc.y + j)].impassible()) {
neighs.add(board[loc.x + i][loc.y + j]);
}
}
}
for (Sprite s : spriteSet) {
if (s.getPlayer() != m.whoseTurn()
&& neighs.contains(board[s.getLocation().y][s.getLocation().x])) {
neighs.remove(board[s.getLocation().y][s.getLocation().x]);
}
}
return neighs;
}
/**
* A* implementation over Tile graph
*
* @param start : coordinates of start
* @param fin : coordinates of end
* @return LinkedList<Tile> representing path
*/
private static LinkedList<? extends Node> getPath(
Node[][] board, Vec2i start, Vec2i fin, Master m, Iterable<? extends Sprite> spriteSet) {
LinkedList<Node> path = new LinkedList<Node>();
PriorityQueue<Node> open = new PriorityQueue<Node>();
open.add(board[start.x][start.y]);
HashSet<Node> done = new HashSet<Node>();
if (board[fin.x][fin.y].impassible()) {
return null;
}
for (Sprite s : spriteSet) {
if (s.getPlayer() == m.whoseTurn() && s.getLocation().equals(new Vec2i(fin.y, fin.x))) {
return null;
}
}
board[start.x][start.y].setDistance(0);
while (!open.isEmpty()) {
Node curr = open.poll();
if (fin.x == curr.getCoords().x && fin.y == curr.getCoords().y) {
Node t = curr;
while (t.getPrev() != null) {
path.addFirst(t);
t = t.getPrev();
}
return path;
}
done.add(curr);
for (Node neigh : Pathfinding.passableNeighbors(board, curr, m, spriteSet)) {
if (done.contains(neigh)) {
continue;
}
if (neigh.getDistance() > curr.getDistance() + 1) {
neigh.setDistance(curr.getDistance() + 1);
neigh.setPrev(curr);
neigh.setEstimate(board[fin.x][fin.y]);
}
open.add(neigh);
}
}
return null;
}
