A、B坐标关系

${\alpha }_{AB}$

$x_A<x_B$

$y_A<y_B$

${\alpha }_{AB}=\alpha \tan \frac{|y_B-y_A|}{|x_B-x_A|}$

$y_A=y_B$

0

$y_A>y_B$

${\alpha }_{AB}=360-\alpha \tan \frac{\left|y_B-y_A\right|}{\left|x_B-x_A\right|}$

$x_A=x_B$

$y_A<y_B$

90

$y_A=y_B$

任意值(程序忽略此种情况)

$y_A>y_B$

270

$x_A>x_B$

$y_A<y_B$

${\alpha }_{AB}=180-\alpha \tan \frac{\left|y_B-y_A\right|}{\left|x_B-x_A\right|}$

$y_A=y_B$

180

$y_A>y_B$

${\alpha }_{AB}=180+\alpha \tan \frac{\left|y_B-y_A\right|}{\left|x_B-x_A\right|}$