MathUtil.java 文件源码

/**
 * Calculate the angle between three points
 *
 * @param pt1 Vector 1
 * @param pt2 Vector 2
 * @param pt0 Vector 0
 * @return The angle (cosine) between the points
 */
public static double angle(Point pt1, Point pt2, Point pt0) {
    double dx1 = pt1.x - pt0.x;
    double dy1 = pt1.y - pt0.y;
    double dx2 = pt2.x - pt0.x;
    double dy2 = pt2.y - pt0.y;
    return (dx1 * dx2 + dy1 * dy2) / Math.sqrt((dx1 * dx1 + dy1 * dy1) * (dx2 * dx2 + dy2 * dy2) + 1e-10);
}