如何从中心点获得点的角度? [英] How to get angle of point from center point?

问题描述

如果我有 2 个点 (x0,y0)，它是圆的中心，另一个点 (x,y)(这是图像中圆边界上的红点).我怎样才能得到点的角度?

If I have 2 points (x0,y0) which is the center of the circle, and another point (x,y) (this is the red dot on the circle boundary in the image). How can I get the angle of the dot?

注意，它应该返回一个以度为单位的角度，从 [0,360).图像中的红点角度约为 70 度.

Note, it should return an angle in degrees, from [0,360). The red dot angle in the image is approximately 70 degrees.

我如何在 python 中做到这一点?

How can I do this in python?

谢谢

这似乎不起作用.

        (dx, dy) = (x0-x, y-y0)
        angle = atan(float(dy)/float(dx))
        if angle < 0:
            angle += 180

推荐答案

你们很亲近 :-)

改变这个:

 angle = atan(float(dy)/float(dx))

为此:

 angle = degrees(atan2(float(dy), float(dx)))

atan2() 函数介于 atan() 之间，因为它会考虑输入的符号并一直绕圆:

The atan2() function is between than atan() because it considers the signs to the inputs and goes all the way around the circle:

atan2(...)
    atan2(y, x)

    Return the arc tangent (measured in radians) of y/x.
    Unlike atan(y/x), the signs of both x and y are considered

degrees() 函数将弧度转换为度数:

The degrees() function converts from radians to degrees:

degrees(...)
    degrees(x)

    Convert angle x from radians to degrees.

此外，正如 Rich 和 Cody 指出的，您需要修正您的 dy 计算.

Also, as Rich and Cody pointed-out you need to fix your dy calculation.

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