/* XXL: The eXtensible and fleXible Library for data processing

Copyright (C) 2000-2011 Prof. Dr. Bernhard Seeger
                        Head of the Database Research Group
                        Department of Mathematics and Computer Science
                        University of Marburg
                        Germany

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library;  If not, see <http://www.gnu.org/licenses/>. 

    http://code.google.com/p/xxl/

*/
package xxl.core.spatial.geometries.predicates;

import xxl.core.predicates.AbstractPredicate;
import xxl.core.spatial.geometries.Geometry2D;

/**
 *	A predicate that returns true if the distance of the given geometries based
 *  on the euclidian-metric is below the specified maximum.
 *
 */
public class DistanceWithin extends AbstractPredicate<Geometry2D>{
	
	/** 
	 * The maximum distance between two objects such that the 
	 * predicate returns <tt>true</tt>. 
	 */
	protected double epsilon;
	
	/** Creates a new DistanceWithin- instance.
    *
	 * @param epsilon the double value represents the maximum distance
	 *        between two objects such that the predicate returns
	 *        <tt>true</tt>.
	 */
	public DistanceWithin(double epsilon){
		super();
		this.epsilon = epsilon;
	}
	
	/** Returns true if the distance between geometry <tt>left</tt> and geometry <tt>right</tt>
	 *  does not exceed the specified maximum distance.
	 *
	 * @see Geometry2D#distance(Geometry2D)
	 * 
	 * @param left first geometry
	 * @param right second geometry
	 * @return returns true if the distance between geometry <tt>left</tt> and geometry <tt>right</tt>
	 *  				does not exceed the specified maximum distance.
	 */
	public boolean invoke(Geometry2D left, Geometry2D right){
		return left.distance(right) <= epsilon;
	}	
}