ribboniterator.java

openmap java写的开源数字地图程序. 用applet实现,可以像google map 那样放大缩小地图.

/**
 *                     RESTRICTED RIGHTS LEGEND
 *
 *                        BBNT Solutions LLC
 *                        A Verizon Company
 *                        10 Moulton Street
 *                       Cambridge, MA 02138
 *                         [phone]
 *
 * Copyright BBNT Solutions LLC 2001, 2002 All Rights Reserved
 *
 */

package com.bbn.openmap.geo;

/**
 * Iterate along a sequence of Ribbons. A Ribbon is a three Geo set,
 * with a RIGHT, CENTER and LEFT Geo in the Ribbon. The location of
 * the LEFT and RIGHT Geo are perpendicular to the great circle path
 * that the CENTER Geo resides on.
 */
public class RibbonIterator {

    protected Geo v1;
    protected Geo v2;
    protected double radius;
    protected Geo gc;
    protected Rotation rotator;
    protected Geo point;
    protected double distance;
    protected boolean hasNext;

    /**
     * Return an iterator that returns Ribbons along the great circle
     * between v1 and v2. The Ribbon points are radius radians appart,
     * and each Ribbon is 2*radius appart.
     */
    public RibbonIterator(Geo v1, Geo v2, double radius) {
        this.v1 = v1;
        this.v2 = v2;
        this.distance = v1.distance(v2);
        this.radius = radius;
        this.gc = v1.crossNormalize(v2);
        this.rotator = new Rotation(gc, 2.0 * radius);
        this.point = v1;
        this.hasNext = true;
    }

    public Object next() {
        if (point != v2 && v1.distance(point) < distance) {
            Ribbon result = new Ribbon(point, gc, radius);
            point = rotator.rotate(point);
            return result;
        } else {
            point = v2;
            return new Ribbon(point, gc, radius);
        }
    }

    public boolean hasNext() {
        return point != v2;
    }

    public void remove() {}
}