Angles

[Magtheridon96]

To find the angle between two points (in radians), you could do:
Atan2(y-y0,x-x0)

But, is it ok if I do this:
Atan(y0-y/x0-x)

If yes, which is faster?

 

[WaterKnight]

Tan is the reversion, taking an angle and returning you the associated ratio of lengths of opposite and adjacent side. Maybe you meant Atan, this should be faster but it is not exactly the same (see).

 

[Magtheridon96]

Oh sorry, yeah I meant Atan

edit
Thanks for the link
Atan(1/0) returns a garbage value
Atan2 is safer (returning pi/2 with Atan2(1,0))

 

[WaterKnight]

1/0 does not return anything because the code halts when encountering zero division.

 

[Magtheridon96]

Details, Details .. x)

 

[HINDYhat]

Also, if you have an angle in the third or fourth quadrant, then your result will be messed up. e.g.:

Atan2(-1, -1) = -3pi/4
Atan(-1/-1) = Atan(1/1) = Atan2(1, 1) = pi/4