private static int computeGScoreIncrease(Cell cell, Cell neighbour) {
int diffX = Math.abs(cell.getXCoor() - neighbour.getXCoor());
int diffY = Math.abs(cell.getYCoor() - neighbour.getYCoor());
if (diffX > 0 && diffY > 0) {
return 14; // diagonal
} else {
return 10; // orthogonal
}
}
private static List<Cell> retrieveNeighbouringCells(
Cell[][] cells, Cell cell, Creature creature) {
List<Cell> neighbours = new ArrayList<Cell>();
int x = cell.getXCoor();
int y = cell.getYCoor();
// left
if (x > 1) {
// up
if (y > 1) {
neighbours.add(cells[x - 1][y - 1]);
neighbours.add(cells[x][y - 1]);
}
// middle
neighbours.add(cells[x - 1][y]);
// down
if (y + 1 < cells[0].length) {
neighbours.add(cells[x - 1][y + 1]);
neighbours.add(cells[x][y + 1]);
}
}
// right
if (x + 1 < cells.length) {
// up
if (y > 1) {
neighbours.add(cells[x + 1][y - 1]);
}
// middle
neighbours.add(cells[x + 1][y]);
// down
if (y + 1 < cells[0].length) {
neighbours.add(cells[x + 1][y + 1]);
}
}
List<Cell> finalNeighbours = new ArrayList<Cell>();
for (Cell neighbour : neighbours) {
if (neighbour.creatureAllowed(creature) && neighbour.getBase() == null) {
finalNeighbours.add(neighbour);
}
}
return finalNeighbours;
}
private static int computeEstimatedCost(Cell currentCell, Cell to) {
return 10
* (Math.abs(currentCell.getXCoor() - to.getXCoor())
+ Math.abs(currentCell.getYCoor() - to.getYCoor()));
}
private static List<Cell> findPath(Cell[][] cells, Cell from, Cell to, Creature creature)
throws NoReachablePathException {
List<Cell> openList = new ArrayList<Cell>();
List<Cell> closedList = new ArrayList<Cell>();
Map<Cell, Cell> cameFrom = new HashMap<Cell, Cell>();
Map<Cell, Integer> gScore = new HashMap<Cell, Integer>();
Map<Cell, Integer> fScore = new HashMap<Cell, Integer>();
/** Initialize start */
openList.add(from);
gScore.put(from, 0);
fScore.put(from, gScore.get(from) + computeEstimatedCost(from, to));
Cell currentCell = null;
while (!openList.isEmpty()) {
/** Find cell with lowest f score */
currentCell = null;
int minFScore = Integer.MAX_VALUE;
for (Cell cell : openList) {
if (fScore.get(cell) < minFScore) {
currentCell = cell;
minFScore = fScore.get(cell);
}
}
if (currentCell == null) {
break;
}
System.out.println("Step: " + currentCell.getXCoor() + " - " + currentCell.getYCoor());
// currentCell is now the cell in the open list with lowest f score
if (currentCell == to) {
return reconstructPath(cameFrom, to);
}
openList.remove(currentCell);
closedList.add(currentCell);
for (Cell neighbour : retrieveNeighbouringCells(cells, currentCell, creature)) {
if (!closedList.contains(neighbour)) {
int gScoreTentative =
gScore.get(currentCell) + computeGScoreIncrease(currentCell, neighbour);
if (!openList.contains(neighbour) || gScoreTentative <= gScore.get(neighbour)) {
cameFrom.put(neighbour, currentCell);
gScore.put(neighbour, gScoreTentative);
fScore.put(neighbour, gScoreTentative + computeEstimatedCost(neighbour, to));
if (!openList.contains(neighbour)) {
openList.add(neighbour);
}
}
}
}
}
throw new NoReachablePathException();
}