ant.java

MASON代表多主体邻里或网络仿真(Multi-Agent Simulator of Neighborhoods or Networks)。它是乔治梅森大学用Java开发的离散事件多主体仿真核心库

                if( x < grid.field.length-1 && y < grid.field[x].length-1 )
                    amount = /*Strict*/Math.max( /*Strict*/Math.max( grid.field[x+1][y+1]-subtractingRatio, minPheromone ), amount );
                grid.field[x][y] = amount;
                pheromoneRatio = amount;
                break;
            }
        }

    public DecisionInfo decideGreedyAction( final SimState state, final int myx, final int myy, final int orientation )
        {

        final AntsForage af = (AntsForage)state;
        final DecisionMaker decisionMaker = af.decisionMaker;

        decisionMaker.reset();

        // add all neighboring cells and move to one of them
        addInformation( state, myx,   myy+1, 0 );
        addInformation( state, myx+1, myy+1, 1 );
        addInformation( state, myx+1, myy,   2 );
        addInformation( state, myx+1, myy-1, 3 );
        addInformation( state, myx,   myy-1, 4 );
        addInformation( state, myx-1, myy-1, 5 );
        addInformation( state, myx-1, myy,   6 );
        addInformation( state, myx-1, myy+1, 7 );

        if( hasFoodItem )
            return decisionMaker.getHomeGreedyDecision( state );
        else
            return decisionMaker.getFoodGreedyDecision( state );

        }

    public void step( final SimState state )
        {
        final AntsForage af = (AntsForage)state;
        final DecisionMaker decisionMaker = af.decisionMaker;
        
        Int2D location = af.buggrid.getObjectLocation(this);
        int myx = location.x;
        int myy = location.y;

        if( justCreated )
            {
            DecisionInfo temp = decideGreedyAction( state, myx, myy, orientation );
            if( temp == null )
                return;
            orientation = temp.orientation;
            justCreated = false;
            }

        final int START=-1;
        int bestx, besty, besto;

        DecisionInfo movingDecision = null;
        if( hasFoodItem )
            movingDecision = decideGreedyAction( state, myx, myy, orientation );
        else
            {
            decisionMaker.reset();
            addInformation( state, myx,   myy+1, 0 );
            addInformation( state, myx+1, myy+1, 1 );
            addInformation( state, myx+1, myy,   2 );
            addInformation( state, myx+1, myy-1, 3 );
            addInformation( state, myx,   myy-1, 4 );
            addInformation( state, myx-1, myy-1, 5 );
            addInformation( state, myx-1, myy,   6 );
            addInformation( state, myx-1, myy+1, 7 );
            int max = 0;
            int howMany = 1;
            for( int i = 1 ; i < decisionMaker.numInfos ; i++ )
                if( decisionMaker.info[max].foodPheromoneAmount ==
                    decisionMaker.info[i].foodPheromoneAmount )
                    {
                    howMany++;
                    }
                else if( decisionMaker.info[max].foodPheromoneAmount <
                         decisionMaker.info[i].foodPheromoneAmount )
                    {
                    max = i;
                    howMany = 1;
                    }
            if( howMany == 1 )
                movingDecision = decideGreedyAction( state, myx, myy, orientation );
            else
                movingDecision = decideAction( state, myx, myy, orientation );
            }
        if( movingDecision == null )
            {
            movingDecision = decideGreedyAction( state, myx, myy, orientation );
            if( movingDecision == null )
                {
                bestx = myx;
                besty = myy;
                besto = orientation;
                }
            else
                {
                bestx = movingDecision.position.x;
                besty = movingDecision.position.y;
                besto = movingDecision.orientation;
                }
            }
        else
            {
            bestx = movingDecision.position.x;
            besty = movingDecision.position.y;
            besto = movingDecision.orientation;
            }

        if( ( bestx != myx || besty != myy ))
            {
            // add some pheromones
            if( hasFoodItem )
                {
                addPheromone(af.toFoodGrid,myx,myy,(/*pheromoneToLeaveBehind*/pheromoneRatio));
                }
            else
                {
                addPheromone(af.toHomeGrid,myx,myy,(/*pheromoneToLeaveBehind*/pheromoneRatio));
                }
            if( bestx != myx && besty != myy )
                pheromoneRatio -= subtractingRatio*1.4142;
            else
                pheromoneRatio -= subtractingRatio;
            if( pheromoneRatio < 0 )
                {
                die( state );
                return;
                }


            // adjust the position of the agent, and then deposit the "to food" and "to home" pheromones
            af.buggrid.setObjectLocation(this,bestx,besty);
            orientation = besto;
            if( ( besty >= AntsForage.HOME_YMIN ) && ( besty <= AntsForage.HOME_YMAX ) &&
                ( bestx >= AntsForage.HOME_XMIN ) && ( bestx <= AntsForage.HOME_XMAX ) )
                {
                if( hasFoodItem )
                    {
                    af.foodCollected++;
                    hasFoodItem = false;
                    pheromoneRatio = 1.0 * maxPheromone;
                    if( GREEDY_REPOSITIONING )
                        {
                        // pick greediest orientation!
                        DecisionInfo temp = decideGreedyAction( state, myx, myy, orientation );
                        if( temp != null )
                            orientation = temp.orientation;
                        else
                            orientation = (orientation+4)%8;
                        }
                    else
                        orientation = (orientation+4)%8; // rotate 180
                    }
                }
            else if(  ( besty >= AntsForage.FOOD_YMIN ) && ( besty <= AntsForage.FOOD_YMAX ) &&
                      ( bestx >= AntsForage.FOOD_XMIN ) && ( bestx <= AntsForage.FOOD_XMAX ) )
                {
                if( !hasFoodItem )
                    {
                    hasFoodItem = true;
                    pheromoneRatio = 1.0 * maxPheromone;
                    if( GREEDY_REPOSITIONING )
                        {
                        // pick greediest orientation!
                        DecisionInfo temp = decideGreedyAction( state, myx, myy, orientation );
                        if( temp != null )
                            orientation = temp.orientation;
                        else
                            orientation = (orientation+4)%8;
                        }
                    else
                        orientation = (orientation+4)%8; // rotate 180
                    }
                }

            timeToLive--;
            if( timeToLive <= 0 )
                {
                die( state );
                return;
                }
            }
        }

    // a few tweaks by Sean
    private Color noFoodColor = Color.black;
    private Color foodColor = Color.red;
    public final void draw(Object object, Graphics2D graphics, DrawInfo2D info)
        {
        if( hasFoodItem )
            graphics.setColor( foodColor );
        else
            graphics.setColor( noFoodColor );

        // this code was stolen from OvalPortrayal2D
        int x = (int)(info.draw.x - info.draw.width / 2.0);
        int y = (int)(info.draw.y - info.draw.height / 2.0);
        int width = (int)(info.draw.width);
        int height = (int)(info.draw.height);
        graphics.fillOval(x,y,width, height);

        }
    
    public Stoppable toDiePointer = null;
    public void die( final SimState state )
        {
        AntsForage antsforage = (AntsForage)state;
        antsforage.numberOfAnts--;
        antsforage.buggrid.remove( this );
        if(toDiePointer!=null) toDiePointer.stop();
        }

    }