C# 数学计算来检索两点之间的角度？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/12891516/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Math Calculation to retrieve angle between two points?
提问by Luke Joshua Park
Possible Duplicate:
How to calculate the angle between two points relative to the horizontal axis?
可能的重复：
如何计算两点之间相对于水平轴的角度？
I've been looking for this for ages and it's just really annoying me so I've decided to just ask...
我一直在寻找这个，这真的让我很烦，所以我决定问问......
Provided I have two points (namely x1, y1, and x2, y2), I would like to calculate the angle between these two points, presuming that when y1 == y2 and x1 > x2 the angle is 180 degrees...
假设我有两个点（即 x1、y1 和 x2、y2），我想计算这两个点之间的角度，假设当 y1 == y2 和 x1 > x2 时，角度是 180 度...
I have the below code that I have been working with (using knowledge from high school) and I just can't seem to produce the desired result.
我有我一直在使用的以下代码（使用高中的知识），但我似乎无法产生所需的结果。
float xDiff = x1 - x2;
float yDiff = y1 - y2;
return (float)Math.Atan2(yDiff, xDiff) * (float)(180 / Math.PI);
Thanks in advance, I'm getting so frustrated...
在此先感谢，我感到非常沮丧......
采纳答案by phant0m
From what I've gathered, you want the following to hold:
根据我收集的信息，您希望保留以下内容：
- Horizontal line:
P1 -------- P2=> 0° - Horizontal line:
P2 -------- P1=> 180°
- 水平线：
P1 -------- P2=> 0° - 水平线：
P2 -------- P1=> 180°
Rotating the horizontal line clockwise
顺时针旋转水平线
You said, you want the angle to increase in clockwise direction.
你说，你想顺时针方向增加角度。
Rotating this line P1 -------- P2such that P1is above P2, the angle must thus be 90°.
旋转这条线P1 -------- P2使其P1在 上方P2，因此角度必须为 90°。
If, however, we rotated in the opposite direction, P1would be below P2and the angle is -90° or 270°.
但是，如果我们以相反的方向旋转，P1则会在下方P2且角度为 -90° 或 270°。
Working with atan2
与 atan2
Basis: Considering P1to be the origin and measuring the angle of P2relative to the origin, then P1 -------- P2will correctly yield 0.
基础：考虑P1为原点并测量P2相对于原点的角度，P1 -------- P2则将正确产生0。
float xDiff = x2 - x1;
float yDiff = y2 - y1;
return Math.Atan2(yDiff, xDiff) * 180.0 / Math.PI;
However, atan2let's the angle increase in CCW direction.
Rotating in CCW direction around the origin, ygoes through the following values:
但是，atan2让我们在 CCW 方向上增加角度。绕原点逆时针方向旋转，y经过以下值：
- y = 0
- y > 0
- y = 0
- y < 0
- y = 0
- y = 0
- y > 0
- y = 0
- y < 0
- y = 0
This means, that we can simply invert the sign of yto flip the direction. But because C#'s coordinates increase from top to bottom, the sign is already reversed when computing yDiff.
这意味着，我们可以简单地反转 的符号y来反转方向。但是因为C#的坐标是从上往下增加的，所以计算的时候符号已经颠倒了yDiff。
