由网友(沿海奔跑的少年。)分享简介：我有一大堆的向量垂直于窗口表面的三维建模软件。预计到xy平面，我想知道在哪个方向，他们所面对的，转换到 8罗盘坐标（北的东北，东的东南亚的南的西南的西和西北的）。I have a bunch of vectors normal to window surfaces in a 3D modelling software...

我有一大堆的向量垂直于窗口表面的三维建模软件。预计到xy平面，我想知道在哪个方向，他们所面对的，转换到 8罗盘坐标（北的东北，东的东南亚的南的西南的西和西北的）。

I have a bunch of vectors normal to window surfaces in a 3D modelling software. Projected to the XY-Plane, I would like to know in which direction they are facing, translated to the 8 compass coordinates (North, North-East, East, South-East, South, South-West, West and North-West).

载体的工作是这样的：

X轴重新presents东西（与东为正） y轴重新presents北 - 南（与北为正） 在这样 （0,1）==北 （1,0）==东 （0，-1）==南 （ - 1,0）==西 the X axis represents East-West (with East being positive) the y axis represents North-South (with North being positive) thus (0, 1) == North (1, 0) == East (0,-1) == South (-1,0) == West

给定一个向量（X，Y）我在寻找最接近的8罗盘坐标。如何做到这一点的任何想法优雅？

Given a vector (x, y) I am looking for the closest of the 8 compass coordinates. Any ideas on how to do this elegantly?

推荐答案

这在Java中，计算值0 ... 7的八个方向：

This works in Java, computing a value 0...7 for the eight directions:

import static java.lang.Math.*;    

int compass = (((int) round(atan2(y, x) / (2 * PI / 8))) + 8) % 8;

结果映射到指南针如下：

The result maps to the compass as follows:

0 => E
1 => NE
2 => N
3 => NW
4 => W
5 => SW
6 => S
7 => SE