rotation.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;

/**
 * Defines a 3-D rotation, M, such that the matrix multiplication, Mv,
 * rotates vector v an angle ,angle, counter clockwise about the Geo,
 * g. See Newman and Sproull, 1973, Principles of Interactive Computer
 * Garaphics, McGraw-Hill, New York, 463-465.
 */
public class Rotation {

    protected Geo g;
    double m00, m11, m22, m01, m10, m12, m21, m02, m20;

    public Rotation(Geo g, double angle) {
        this.g = g;
        this.setAngle(angle);
    }

    private void setAngle(double angle) {
        double x = g.x();
        double y = g.y();
        double z = g.z();
        double c = Math.cos(angle);
        double s = Math.sin(angle);
        double b = 1.0 - c;
        double bx = b * x;
        double by = b * y;
        double bz = b * z;
        double bxx = bx * x;
        double bxy = bx * y;
        double bxz = bx * z;
        double byy = by * y;
        double byz = by * z;
        double bzz = bz * z;
        double sx = s * x;
        double sy = s * y;
        double sz = s * z;
        m00 = c + bxx;
        m11 = c + byy;
        m22 = c + bzz;
        m01 = (-sz) + bxy;
        m10 = sz + bxy;
        m12 = (-sx) + byz;
        m21 = sx + byz;
        m02 = sy + bxz;
        m20 = (-sy) + bxz;

        /**
         * System.out.println (" Rotation " + m00 + " " + m11 + " " +
         * m22 + "\n" + m01 + " " + m10 + " " + m12 + "\n" + m21 + " " +
         * m02 + " " + m20);
         */
    }

    public Geo rotate(Geo v) {
        double x = v.x(), y = v.y(), z = v.z();
        return new Geo(m00 * x + m01 * y + m02 * z,
                       m10 * x + m11 * y + m12 * z,
                       m20 * x + m21 * y + m22 * z);
    }
}