/*
* Last change: $Date: 2004/05/04 03:09:38 $
* $Revision: 1.6 $
*
* Copyright (c) 2004, The Black Sheep, Department of Computer Science, The University of Auckland
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
* Neither the name of The Black Sheep, The Department of Computer Science or The University of Auckland nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package rescuecore.sample;
import rescuecore.*;
import rescuecore.objects.*;
import rescuecore.event.*;
import rescuecore.commands.AKChannel;
import java.util.*;
/**
This is a sample implementation of a police force. This agent will attempt to clear the closest blocked road it knows about. If it doesn't know anything then it moves randomly.
*/
public class SamplePoliceForce extends PlatoonAgent {
private final static byte CHANNEL = 2;
/**
A list of known targets
*/
private List targets;
/**
Construct a new SamplePoliceForce
*/
public SamplePoliceForce() {
super(RescueConstants.TYPE_POLICE_FORCE); // We need to specify that we can only be a police force
targets = new ArrayList();
}
/**
Get a reference the the PoliceForce controlled by this agent
@return the PoliceForce controlled by this agent
*/
private PoliceForce me() {
return (PoliceForce)memory.lookup(id);
}
public void initialise(RescueObject[] knowledge) {
// Add a memory listener so that we get informed about changes to the roads
super.initialise(knowledge);
memory.addMemoryListener(new MemoryListener() {
public void objectAdded(ObjectAddedEvent event) {
RescueObject o = event.getObject();
if (o.isRoad()) {
if (((Road)o).isBlocked()) targets.add(o); // Add to target list if it is a blocked road
}
}
public void objectChanged(ObjectChangedEvent event) {
RescueObject o = event.getObject();
if (o.isRoad() && event.getProperty()==RescueConstants.PROPERTY_BLOCK) { // We only care about the blockedness of the road - we can ignore all other updates
if (((Road)o).isBlocked()) targets.add(o); // Add to target list if it is a blocked road
else targets.remove(o); // Otherwise remove it from the target list
}
}
});
// log("Initialised"); // Log a debugging message
}
public void sense() {
// Is this the first timestep?
if (timeStep==1) {
// Listen on the right channel
appendCommand(new AKChannel(id,timeStep,CHANNEL));
}
// log("Sense"); // Log a debugging message
// Am I on a blocked road?
RescueObject location = getLocation();
if (location.isRoad() && ((Road)location).isBlocked()) {
// Yes. Clear it!
// log("Clearing "+location);
clear((Road)location);
tell(("Clearing "+location.getID()).getBytes(),CHANNEL);
return;
}
// Sort the targets by distance from me
// log("Sorting targets");
SampleSearch.sortByDistance(targets,me(),memory);
// Find a valid target
for (Iterator it = targets.iterator();it.hasNext();) {
// Try to plan a path to the next best target
Road next = (Road)it.next();
if (!next.isBlocked()) {
// If the next target is not blocked then remove it from our target list
it.remove();
continue;
}
// log("Trying to plan path to "+next);
int[] path = SampleSearch.breadthFirstSearch(getLocation(),next,memory); // Find a path from my current location to the target
if (path!=null) {
// We've found a path. Hooray!
// Send a move command and we're finished
// log("Moving to "+next);
move(path);
return;
}
// log("No path");
}
// We couldn't find a good target. Pick a random road and try moving there instead
// log("No good targets - picking a Road at random");
Collection<RescueObject> allRoads = memory.getObjectsOfType(RescueConstants.TYPE_ROAD); // Find all roads
Road[] roads = new Road[allRoads.size()];
allRoads.toArray(roads);
Road target = (Road)roads[(int)(Math.random()*roads.length)]; // Pick one at random
// log("Random target: "+target+". Planning path");
// Plan a path
int[] path = SampleSearch.breadthFirstSearch(getLocation(),target,memory);
if (path!=null) {
// log("Moving to "+target);
move(path); // Move if the path is valid
}
else {
// If we couldn't move randomly then just give up
// log("I give up");
}
}
protected void hear(int from, byte[] msg, byte channel) {
// System.out.println("Received message from "+from+": "+String.valueOf(msg));
}
}