/**
* Get the best move.
*
* @param space The 2D space to move in.
* @param sourcepos The source position.
* @param eval The move evaluator.
* @return The direction to go ('none', if no move at all is better than moving in any direction).
*/
public static String evaluateMoves(Grid2D space, IVector2 sourcepos, IMoveEvaluator eval) {
String ret = null;
Map moves = new HashMap();
moves.put(DIRECTION_NONE, new Vector2Int(sourcepos.getXAsInteger(), sourcepos.getYAsInteger()));
moves.put(
DIRECTION_LEFT, new Vector2Int(sourcepos.getXAsInteger() - 1, sourcepos.getYAsInteger()));
moves.put(
DIRECTION_RIGHT, new Vector2Int(sourcepos.getXAsInteger() + 1, sourcepos.getYAsInteger()));
moves.put(
DIRECTION_UP, new Vector2Int(sourcepos.getXAsInteger(), sourcepos.getYAsInteger() - 1));
moves.put(
DIRECTION_DOWN, new Vector2Int(sourcepos.getXAsInteger(), sourcepos.getYAsInteger() + 1));
// Get max value of positions not filled with obstacles.
double maxval = Double.NEGATIVE_INFINITY;
for (Iterator it = moves.keySet().iterator(); it.hasNext(); ) {
IVector2 pos = (IVector2) moves.get(it.next());
Collection obstacles = space.getSpaceObjectsByGridPosition(pos, "obstacle");
if (obstacles != null && !obstacles.isEmpty()) {
it.remove();
} else {
maxval = Math.max(maxval, eval.evaluateMove(pos));
}
}
// Retain only the best move(s).
for (Iterator it = moves.keySet().iterator(); it.hasNext(); ) {
IVector2 pos = (IVector2) moves.get(it.next());
if (eval.evaluateMove(pos) < maxval) {
it.remove();
}
}
// System.out.println("Moves: "+moves);
// Chose randomly one of the remaining equally good moves.
if (moves.size() > 0) {
int chosen = (int) (Math.random() * moves.size());
Iterator it = moves.keySet().iterator();
for (int i = 0; i <= chosen; i++) {
ret = (String) it.next();
}
}
return ret;
}
/**
* Get the possible moves.
*
* @param space The 2D space to move in.
* @param sourcepos The source position.
* @return The directions to go (i.e. all possible directions excluding 'none' or an array with
* only 'none').
*/
public static String[] getPossibleDirections(Grid2D space, IVector2 sourcepos) {
Map moves = new HashMap();
moves.put(
DIRECTION_LEFT, new Vector2Int(sourcepos.getXAsInteger() - 1, sourcepos.getYAsInteger()));
moves.put(
DIRECTION_RIGHT, new Vector2Int(sourcepos.getXAsInteger() + 1, sourcepos.getYAsInteger()));
moves.put(
DIRECTION_UP, new Vector2Int(sourcepos.getXAsInteger(), sourcepos.getYAsInteger() - 1));
moves.put(
DIRECTION_DOWN, new Vector2Int(sourcepos.getXAsInteger(), sourcepos.getYAsInteger() + 1));
for (Iterator it = moves.keySet().iterator(); it.hasNext(); ) {
IVector2 pos = (IVector2) moves.get(it.next());
Collection obstacles = space.getSpaceObjectsByGridPosition(pos, "obstacle");
if (obstacles != null && !obstacles.isEmpty()) {
it.remove();
}
}
return moves.isEmpty()
? new String[] {DIRECTION_NONE}
: (String[]) moves.keySet().toArray(new String[moves.size()]);
}
/**
* Performs the action.
*
* @param parameters parameters for the action
* @param space the environment space
* @return action return value
*/
public Object perform(Map parameters, IEnvironmentSpace space) {
// System.out.println("move action: "+parameters);
Grid2D grid = (Grid2D) space;
IComponentIdentifier actor = (IComponentIdentifier) parameters.get(ISpaceAction.ACTOR_ID);
String direction = (String) parameters.get(PARAMETER_DIRECTION);
ISpaceObject avatar = grid.getAvatar(actor);
if (null == space.getSpaceObject(avatar.getId())) {
throw new RuntimeException("No such object in space: " + avatar);
}
IVector2 pos = (IVector2) avatar.getProperty(Space2D.PROPERTY_POSITION);
boolean skip = false;
if (DIRECTION_LEFT.equals(direction)) {
pos = new Vector2Int(pos.getXAsInteger() - 1, pos.getYAsInteger());
} else if (DIRECTION_RIGHT.equals(direction)) {
pos = new Vector2Int(pos.getXAsInteger() + 1, pos.getYAsInteger());
} else if (DIRECTION_UP.equals(direction)) {
pos = new Vector2Int(pos.getXAsInteger(), pos.getYAsInteger() - 1);
} else if (DIRECTION_DOWN.equals(direction)) {
pos = new Vector2Int(pos.getXAsInteger(), pos.getYAsInteger() + 1);
} else if (DIRECTION_NONE.equals(direction)) {
skip = true;
} else {
throw new RuntimeException("Unknown move direction: " + direction);
}
if (!skip) {
Collection obstacles = grid.getSpaceObjectsByGridPosition(pos, "obstacle");
if (obstacles != null && !obstacles.isEmpty()) {
throw new RuntimeException(
"Cannot move '" + direction + "' due to obstacles: " + obstacles);
}
// Preys can not "tunnel" through hunters, i.e. move from the field
// where the hunter is now to the field where the hunter was before.
if (avatar.getType().equals("prey")) {
Collection hunters =
grid.getSpaceObjectsByGridPosition(
(IVector2) avatar.getProperty(Space2D.PROPERTY_POSITION), "hunter");
if (hunters != null) {
pos = grid.adjustPosition(pos); // Hack!!! Position only converted in setPosition().
for (Iterator it = hunters.iterator(); it.hasNext(); ) {
ISpaceObject hunter = (ISpaceObject) it.next();
if (pos.equals(hunter.getProperty(PROPERTY_LASTPOS))) {
// System.out.println("Cannot move '"+direction+"' due to hunter: "+hunter);
throw new RuntimeException(
"Cannot move '" + direction + "' due to hunter: " + hunter);
}
}
}
}
// Remember last position of hunter (required for detecting "tunneling").
else if (avatar.getType().equals("hunter")) {
avatar.setProperty(PROPERTY_LASTPOS, avatar.getProperty(Space2D.PROPERTY_POSITION));
}
grid.setPosition(avatar.getId(), pos);
}
return null;
}