src/appletbots/friendly/FriendlyAgent.java

   1 /*
   2  * Copyright (c) 2002 Erik Rasmussen - All Rights Reserverd
   3  */
   4 package appletbots.friendly;
   5
   6 import appletbots.Agent;
   7 import appletbots.geometry.Vector;
   8
   9 import java.awt.*;
  10 import java.util.List;
  11
  12 /**
  13  * A friendly agent looks at all the other agents he can see and randomly
  14  * selects one to be his friend.  However, he can only make another agent his
  15  * friend if the other agent does not already have the agent selected as his
  16  * friend.  The friendly agent then tries to move toward his friend by
  17  * accelerating towards him.  The agent remembers who his friend is and
  18  * continues to accelerate towards him as long as the friend remains visible.
  19  * If the agent ever loses sight of his friend he simply selects another one at
  20  * random given the selection criteria stated above.  If ever a friend cannot
  21  * be found the agent accelerates in a random direction to search for one.
  22  *
  23  * @author Erik Rasmussen
  24  */
  25 public class FriendlyAgent extends Agent
  26 {
  27         /**
  28          * The selected friend
  29          */
  30         private Agent friend;
  31
  32         /**
  33          * Constructs a new FriendlyAgent with the given parameters
  34          *
  35          * @param size            The agent's radius
  36          * @param sight           The distance the agent can see
  37          * @param maxSpeed        The maximum speed the agent can travel
  38          * @param maxAcceleration The maximum acceleration for this agent
  39          */
  40         public FriendlyAgent(final int size, final int sight, final double maxSpeed, final double maxAcceleration)
  41         {
  42                 super(size, sight, maxSpeed, maxAcceleration);
  43                 this.color = Color.cyan;
  44         }
  45
  46         /**
  47          * Observes the world, and follows the Friendly Agent Algorithm.
  48          */
  49         public void observeWorld()
  50         {
  51                 final List neighbors = world.getNeighbors(this);
  52                 if (neighbors.isEmpty())
  53                         friend = null;
  54                 else
  55                 {
  56                         if (friend == null || !neighbors.contains(friend))
  57                         {
  58                                 // remove neighbors that have me as their friend
  59                                 for (int i = 0; i < neighbors.size(); i++)
  60                                 {
  61                                         final Agent neighbor = (Agent) neighbors.get(i);
  62                                         if (neighbor instanceof FriendlyAgent)
  63                                         {
  64                                                 final FriendlyAgent friendlyNeighbor = (FriendlyAgent) neighbor;
  65                                                 if (equals(friendlyNeighbor.getFriend()))
  66                                                         neighbors.remove(i--);
  67                                         }
  68                                 }
  69                                 if (neighbors.isEmpty())
  70                                         friend = null;
  71                                 else
  72                                 {
  73                                         // can't follow old one, pick a random neighbor and go to him
  74                                         final int randIndex = (int) Math.floor(Math.random() * neighbors.size());
  75                                         friend = (Agent) neighbors.get(randIndex);
  76                                 }
  77                         }
  78                 }
  79                 if (friend != null)
  80                         setAcceleration(world.getVectorToObject(this, friend));
  81                 else
  82                         setAcceleration(Vector.getRandom(maxAcceleration));
  83         }
  84
  85         /**
  86          * Returns the selected friend
  87          *
  88          * @return The selected friend
  89          */
  90         public Agent getFriend()
  91         {
  92                 return friend;
  93         }
  94 }