Does anyone know of a way to make a sprite face the user vertically if the user goes under or over it?

I set all the rotate values of my sprites to 0.0, making them face me in the horizontal direction I am from them. However, I cannot seem to make them face up toward me if I am over them, or down toward me if I am under them. Does anyone know how to make sprites face you vertically instead of just horizontally?

Replace the ball.x with your player entitiy

Thanks TheLiam. I will try that when I get back to programming for the game with Lite-C.

@TheLiam
i think you made a small mistake.
you wrote this:
vec_set(temp,ball.x);
vec_sub(temp,my.x);
vec_to_angle(my.pan,temp);

but temp is a vector, so it has to look like this :
vec_set(temp.x,ball.x);
vec_sub(temp.x,my.x);
vec_to_angle(my.pan,temp.x);

@alibaba: you are wrong. If you define the vector with "VECTOR temp;" then the x is not necessary at the vec_set. You need it only if you use a pointer to a entity so the vec_set knows witch vector of the entity you want to set (x, pan, red...)

vec_set expect a VECTOR* and temp is one.

EDIT: of course you can also use temp.x, works too