Java:以度为单位计算两点之间的角度

Question

我需要为自己的Point类计算两点之间的角度,点a应该是中心点.

方法:

public float getAngle(Point target) {
    return (float) Math.toDegrees(Math.atan2(target.x - x, target.y - y));
}

测试1://返回45

Point a = new Point(0, 0);
    System.out.println(a.getAngle(new Point(1, 1)));

测试2://返回-90,预期:270

Point a = new Point(0, 0);
    System.out.println(a.getAngle(new Point(-1, 0)));

如何将返回的结果转换为0到359之间的数字？

Answer 1

你可以添加以下内容:

public float getAngle(Point target) {
    float angle = (float) Math.toDegrees(Math.atan2(target.y - y, target.x - x));

    if(angle < 0){
        angle += 360;
    }

    return angle;
}

顺便问一下,为什么你不想在这里使用双人？

Answer 2

我从johncarls解决方案开始,但需要调整它以获得我所需要的.主要是,我需要它在角度增加时顺时针旋转.我还需要0度指向北方.他的解决方案让我很接近,但我决定发布我的解决方案,以防它帮助其他任何人.

我添加了一些额外的注释,以帮助解释我对函数的理解,以防您需要进行简单的修改.

/**
 * Calculates the angle from centerPt to targetPt in degrees.
 * The return should range from [0,360), rotating CLOCKWISE, 
 * 0 and 360 degrees represents NORTH,
 * 90 degrees represents EAST, etc...
 *
 * Assumes all points are in the same coordinate space.  If they are not, 
 * you will need to call SwingUtilities.convertPointToScreen or equivalent 
 * on all arguments before passing them  to this function.
 *
 * @param centerPt   Point we are rotating around.
 * @param targetPt   Point we want to calcuate the angle to.  
 * @return angle in degrees.  This is the angle from centerPt to targetPt.
 */
public static double calcRotationAngleInDegrees(Point centerPt, Point targetPt)
{
    // calculate the angle theta from the deltaY and deltaX values
    // (atan2 returns radians values from [-PI,PI])
    // 0 currently points EAST.  
    // NOTE: By preserving Y and X param order to atan2,  we are expecting 
    // a CLOCKWISE angle direction.  
    double theta = Math.atan2(targetPt.y - centerPt.y, targetPt.x - centerPt.x);

    // rotate the theta angle clockwise by 90 degrees 
    // (this makes 0 point NORTH)
    // NOTE: adding to an angle rotates it clockwise.  
    // subtracting would rotate it counter-clockwise
    theta += Math.PI/2.0;

    // convert from radians to degrees
    // this will give you an angle from [0->270],[-180,0]
    double angle = Math.toDegrees(theta);

    // convert to positive range [0-360)
    // since we want to prevent negative angles, adjust them now.
    // we can assume that atan2 will not return a negative value
    // greater than one partial rotation
    if (angle < 0) {
        angle += 360;
    }

    return angle;
}