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The Jadex BDI applications package contain
several example applications, benchmarks and
testcases using BDI agents.
package jadex.bdi.examples.hunterprey;
import jadex.bridge.service.types.cms.IComponentDescription;
import jadex.commons.SimplePropertyObject;
import jadex.extension.envsupport.environment.IEnvironmentSpace;
import jadex.extension.envsupport.environment.ISpaceAction;
import jadex.extension.envsupport.environment.ISpaceObject;
import jadex.extension.envsupport.environment.space2d.Grid2D;
import jadex.extension.envsupport.environment.space2d.Space2D;
import jadex.extension.envsupport.math.IVector2;
import jadex.extension.envsupport.math.Vector2Int;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
/**
* Action allowing a creature to move.
*/
public class MoveAction extends SimplePropertyObject implements ISpaceAction
{
//-------- constants --------
/** The move direction parameter. */
public static final String PARAMETER_DIRECTION = "direction";
/** The last position property (only for hunters). */
public static final String PROPERTY_LASTPOS = "lastpos";
/** The move direction left. */
public static final String DIRECTION_LEFT = "left";
/** The move direction right. */
public static final String DIRECTION_RIGHT = "right";
/** The move direction up. */
public static final String DIRECTION_UP = "up";
/** The move direction down. */
public static final String DIRECTION_DOWN = "down";
/** Placeholder for "no move" action. */
public static final String DIRECTION_NONE = "none";
//--------- IAgentAction interface --------
/**
* 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;
IComponentDescription actor = (IComponentDescription)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;
}
/**
* Get the best way to go towards a direction.
* @param space The 2D space to move in.
* @param sourcepos The source position.
* @param targetpos The target position.
* @return The way to go (if any).
*/
// Todo: A*
public static String getDirection(final Grid2D space, IVector2 sourcepos, final IVector2 targetpos)
{
String ret = evaluateMoves(space, sourcepos, new IMoveEvaluator()
{
public double evaluateMove(IVector2 position)
{
// The smaller the distance, the better the move.
return -space.getDistance(position, targetpos).getAsDouble();
}
});
return ret;
}
/**
* Move to stay away from the given objects.
* @param space The 2D space to move in.
* @param sourcepos The source position.
* @param objects The objects to avoid.
* @return The direction to go ('none', if no move at all is better than moving in any direction).
*/
public static String getAvoidanceDirection(final Grid2D space, IVector2 sourcepos, final ISpaceObject[] objects)
{
String ret = evaluateMoves(space, sourcepos, new IMoveEvaluator()
{
public double evaluateMove(IVector2 position)
{
// The bigger the minimal distance, the better the move.
double mindist = Double.POSITIVE_INFINITY;
for(int i=0; i0)
{
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()]);
}
//-------- helper classes --------
/**
* Interface for evaluating moves.
*/
public static interface IMoveEvaluator
{
/**
* Evaluate the move to the given position.
* @param position The position to move to.
* @return A number representing the move value (bigger=better).
*/
public double evaluateMove(IVector2 position);
}
}