计算两条线之间的角度而不必计算斜率？ （JAVA）

问题描述

我有两条线：L1和L2。我想计算两条线之间的角度。 L1具有以下几点：

它被声明为 double atan2（double y，double x）并转换直角坐标（ x，y）与极坐标（r，theta）的角度 theta

所以我会将你的代码重写为

  public static double angleBetween2Lines（Line2D line1，Line2D line2）
 {
 double angle1 = Math.atan2（line1.getY1（） -  line1.getY2（），
 line1.getX1（） -  line1.getX2（ ））; 
 double angle2 = Math.atan2（line2.getY1（） -  line2.getY2（），
 line2.getX1（） -  line2.getX2（））; 
返回angle1-angle2; 
} 
  

I have two Lines: L1 and L2. I want to calculate the angle between the two lines. L1 has points: {(x1, y1), (x2, y2)} and L2 has points: {(x3, y3), (x4, y4)}.

How can I calculate the angle formed between these two lines, without having to calculate the slopes? The problem I am currently having is that sometimes I have horizontal lines (lines along the x-axis) and the following formula fails (divide by zero exception):

arctan((m1 - m2) / (1 - (m1 * m2)))

where m1 and m2 are the slopes of line 1 and line 2 respectively. Is there a formula/algorithm that can calculate the angles between the two lines without ever getting divide-by-zero exceptions? Any help would be highly appreciated.

This is my code snippet:

// Calculates the angle formed between two lines
public static double angleBetween2Lines(Line2D line1, Line2D line2)
{
    double slope1 = line1.getY1() - line1.getY2() / line1.getX1() - line1.getX2();
    double slope2 = line2.getY1() - line2.getY2() / line2.getX1() - line2.getX2();
    double angle = Math.atan((slope1 - slope2) / (1 - (slope1 * slope2)));
    return angle;
}

Thanks.

解决方案

The atan2 function eases the pain of dealing with atan.

It is declared as double atan2(double y, double x) and converts rectangular coordinates (x,y) to the angle theta from the polar coordinates (r,theta)

So I'd rewrite your code as

public static double angleBetween2Lines(Line2D line1, Line2D line2)
{
    double angle1 = Math.atan2(line1.getY1() - line1.getY2(),
                               line1.getX1() - line1.getX2());
    double angle2 = Math.atan2(line2.getY1() - line2.getY2(),
                               line2.getX1() - line2.getX2());
    return angle1-angle2;
}

这篇关于计算两条线之间的角度而不必计算斜率？ （JAVA）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！