找到一个点的“运动方向”(角度)

I'm working on a pretty cool project where I'm collecting data about the movement of a cursor, but I've run into an issue where I think I could use some help. I am constantly reading in data about the x and y position of the cursor (along with other relevant data), and once the cursor exceeds a certain threshold in the y-dimension, I need to calculate the movement direction (angle). Let me illustrate with a figure I drew:I'm working on a pretty cool project where I'm