attractorfield.java

能在 ns-2 下模拟出一个使用 swarm 算法通讯的网络

/*******************************************************************************
 ** BonnMotion - a mobility scenario generation and analysis tool             **
 ** Copyright (C) 2002, 2003 University of Bonn                               **
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 ** This program is free software; you can redistribute it and/or modify      **
 ** it under the terms of the GNU General Public License as published by      **
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 ** but WITHOUT ANY WARRANTY; without even the implied warranty of            **
 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             **
 ** GNU General Public License for more details.                              **
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 ** You should have received a copy of the GNU General Public License         **
 ** along with this program; if not, write to the Free Software               **
 ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA **
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package edu.bonn.cs.iv.bonnmotion;

import java.util.Vector;

public class AttractorField {
	class Attractor {
		public final Position pos;
		public final double level;
		public final double stdDev;
		
		public Attractor(Position pos, double level, double stdDev) {
			this.pos = pos;
			this.level = level;
			this.stdDev = stdDev;
		}
	}

	protected Vector attractors = new Vector();
	/** Sum over all level-values. */
	protected double lTotal = 0.0;
	
	protected final double x;
	protected final double y;
	
	public AttractorField(double x, double y) {
		this.x = x;
		this.y = y;
	}
	
	public void add(Position attractor, double level, double stdDev) {
		attractors.addElement(new Attractor(attractor, level, stdDev));
		lTotal += level;
	}
	
	public void add(double[] param) {
		for (int p = 0; p < param.length; p += 4)
			if (param.length - p >= 4)
				add(new Position(param[p], param[p+1]), param[p+2], param[p+3]);
			else
				System.out.println("warning: attraction field argument list has wrong number of elements!");
	}

	public Position getPos(double rndUniform1, double rndUniform2, double rndGaussian) {
		double r = rndUniform1 * lTotal;
		double s = 0.0;
		Attractor a = null;
		int i = 0;
		while ((i < attractors.size()) && (r >= s)) {
			a = (Attractor)attractors.elementAt(i++);
			s += a.level;
		}
		if ((r >= s) || (a == null)) {
			System.out.println("AttractorField.getPos: Somethings going wrong here");
			System.exit(0);
		}
		double dir = Math.PI * rndUniform2; // only half circle cause we can have negative distance as well
		double dist = rndGaussian * a.stdDev;
		Position rVal = new Position(a.pos.x + Math.cos(dir) * dist, a.pos.y + Math.sin(dir) * dist);
		if ((rVal.x >= 0.0) && (rVal.y >= 0.0) && (rVal.x <= x) && (rVal.y <= y))
			return rVal;
		else
			return null;
	}
	
	public Scenario createScenario(int nodes) {
		Scenario s = new Scenario(nodes, x, y, 1.0, 0.0, System.currentTimeMillis());
		java.util.Random rnd = new java.util.Random();
		for (int i = 0; i < nodes; i++) {
			Position pos;
			do {
				pos = getPos(rnd.nextDouble(), rnd.nextDouble(), rnd.nextGaussian());
			} while (pos == null);
			s.getNode(i).add(0.0, pos);
		}
		return s;
	}
	
	public static void main(String[] args) {
		AttractorField a = new AttractorField(1000.0, 1000.0);
		java.util.Random rnd = new java.util.Random();
		a.add(new Position(250.0, 250.0), 1.0, 350.0);
		a.add(new Position(250.0, 750.0), 1.0, 350.0);
		a.add(new Position(750.0, 250.0), 1.0, 350.0);
		a.add(new Position(750.0, 750.0), 1.0, 350.0);
		for (int i = 0; i < 500; i++) {
			Position p = null;
			while (p == null) {
				p = a.getPos(rnd.nextDouble(), rnd.nextDouble(), rnd.nextGaussian());
			}
			System.out.println("" + p.x + " " + p.y);
		}
	}
}