找到与枢轴相关的点的角度 [英] find the angle of point related to pivot

问题描述

已经有几天我在做一个项目，我必须在其中使用凸包，以及特定的graham扫描方法.问题一直解决到我要对点进行排序为止. 故事就是我从Point类型中收集了一堆点，它们的坐标是亲戚.意味着它们来自鼠标事件x和y.因此，我收集了鼠标位置作为点的x和y.我想找到与枢轴点有关的角度.有人有一段代码可以计算该角度吗? 非常感谢，下面的图片是我需要的:

It’s been days that I’m working on a project which I have to use convex hull in it, and specific method of graham scan. The problem has been solved till the place I want to sort the points. So the story is that I have collected bunch of points which they are from the type Point and their coordinates are relatives. Mean they come from the mouse event x and y. So I have collected the mouse positions as x and y of the points. And I want to find the angle related to the pivot point. Does anyone have a piece of code to calculate that angle? Many and many thanks, the image below is what I need:

推荐答案

使用

Math.atan2(dy, dx)

其中dy和dx代表该点和枢轴点之间的垂直和水平差.

where dy and dx represent the vertical and horizontal difference between the point and pivot point.

一些注意事项:

• 参考(0弧度)按惯例是指向右侧，而不是图像中的左侧.如果您真的想从左侧进行测量，则必须执行Math.PI - angle进行转换.

Math-三角函数以弧度工作.要将结果转换为度，可以使用Math.toDegrees.

The Math-trigonometry functions work in radians. To convert the results to degrees, you can use Math.toDegrees.

在数学世界中，增大的y值指向上方.在您的图像中，它们的指向下方.

In the mathematical world, increasing y-values point upwards. In your image, their pointing downwards.

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