Return the angle between points A and B using trigonometry. A being the center of the unit circle. - Android Graphics

Android examples for Graphics:Path Point

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Description

Return the angle between points A and B using trigonometry. A being the center of the unit circle.

Demo Code


//package com.java2s;

public class Main {
    /**//from w  w  w  .  ja v  a  2 s .co  m
     * Return the angle between points A and B using trigonometry.<br />
     * A being the center of the unit circle.
     *
     * @param xa The abscissa of point A.
     * @param ya The ordinate of point A.
     * @param xb The abscissa of point B.
     * @param yb The ordinate of point B.
     * @param reverse True if the ordinates goes down instead of up. False otherwise.
     * @return The angle in degrees.
     */
    public static double angleInDegrees(double xa, double ya, double xb,
            double yb, boolean reverse) {
        return Math.toDegrees(angleInRadiant(xa, ya, xb, yb, reverse));
    }

    /**
     * Return the angle between points A and B using trigonometry.<br />
     * A being the center of the unit circle.
     *
     * @param xa The abscissa of point A.
     * @param ya The ordinate of point A.
     * @param xb The abscissa of point B.
     * @param yb The ordinate of point B.
     * @return The angle in radiant.
     */
    public static double angleInDegrees(double xa, double ya, double xb,
            double yb) {
        return angleInDegrees(xa, ya, xb, yb, false);
    }

    /**
     * Return the angle between points A and B using trigonometry.<br />
     * A being the center of the unit circle.
     *
     * @param xa The abscissa of point A.
     * @param ya The ordinate of point A.
     * @param xb The abscissa of point B.
     * @param yb The ordinate of point B.
     * @param reverse True if the ordinates goes down instead of up. False otherwise.
     * @return The angle in radiant.
     */
    public static double angleInRadiant(double xa, double ya, double xb,
            double yb, boolean reverse) {
        if (reverse) {
            return Math.atan2(ya - yb, xb - xa);
        }
        // Standard formula
        return Math.atan2(yb - ya, xb - xa);
    }
}

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