VectorUtils.java

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/* *********************************************************************** *
 * project: org.matsim.*
 * ScaleEndPointUtil
 *                                                                         *
 * *********************************************************************** *
 *                                                                         *
 * copyright       : (C) 2009 by the members listed in the COPYING,        *
 *                   LICENSE and WARRANTY file.                            *
 * email           : info at matsim dot org                                *
 *                                                                         *
 * *********************************************************************** *
 *                                                                         *
 *   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  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *   See also COPYING, LICENSE and WARRANTY file                           *
 *                                                                         *
 * *********************************************************************** */
package org.matsim.vis.vecmathutils;

import java.awt.geom.Point2D;

import org.matsim.core.utils.collections.Tuple;

public class VectorUtils {

    public static Tuple<Point2D.Double, Point2D.Double> scaleVector(final Point2D.Double start, final Point2D.Double end,
            double scaleFactor) {
        
        return calculateScaledVector(start, end, scaleFactor);
    }

    @Deprecated
    public static Tuple<Point2D.Double, Point2D.Double> scaleVectorStart(final Point2D.Double start, final Point2D.Double end,
            double scaleFactor) {
        
        Tuple<Point2D.Double, Point2D.Double> scaledVector = calculateScaledVector(start, end, scaleFactor);
        return new Tuple<Point2D.Double, Point2D.Double>(scaledVector.getFirst(), end);
    }
    
    @Deprecated
    public static Tuple<Point2D.Double, Point2D.Double> scaleVectorEnd(final Point2D.Double start, final Point2D.Double end,
            double scaleFactor) {
        
        Tuple<Point2D.Double, Point2D.Double> scaledVector = calculateScaledVector(start, end, scaleFactor);
        return new Tuple<Point2D.Double, Point2D.Double>(start, scaledVector.getSecond());
    }
    
    
    private static Tuple<Point2D.Double, Point2D.Double> calculateScaledVector(
            final Point2D.Double start, final Point2D.Double end,
            double scaleFactor) {
        //norm
        Point2D.Double.Double delta = new Point2D.Double.Double(end.x - start.x, end.y - start.y);
        double length = Math.sqrt(Math.pow(delta.x, 2) + Math.pow(delta.y, 2));
        Point2D.Double.Double deltaNorm = new Point2D.Double.Double(delta.x / length, delta.y / length);
        //scale
        double scaledLength = length * scaleFactor;
        double offset = (length - scaledLength) / 2;
        Point2D.Double scaledEnd = new Point2D.Double(start.x + ((length - offset) * deltaNorm.x), start.y
                + ((length - offset) * deltaNorm.y));
        Point2D.Double scaledStart = new Point2D.Double(start.x
                + (offset * deltaNorm.x), start.y
                + (offset * deltaNorm.y));
        Tuple<Point2D.Double, Point2D.Double> scaledVector = new Tuple<Point2D.Double, Point2D.Double>(scaledStart, scaledEnd);
        return scaledVector;
    }
}