math - Calculating if an angle is between two angles

Question

So I am making a little game where I am checking if a character can "see" another where character A can see character B if A is within a certain distance of B, and the direction in degrees of A is +/- 45 degrees of the angle B is facing.

Currently, I do a little calculation where I'm checking if

(facingAngle - 45) =< angleOfTarget =< (facingAngle + 45)

This works fine except for when we cross the 360 degree line.

Let's say facingAngle = 359, angleOfTarget = 5. In this situation, the target is only 6 degrees off center, so I want my function to return true. Unfortunately, 5 is not between 314 and 404.

Answer 1

Just try

anglediff = (facingAngle - angleOfTarget + 180 + 360) % 360 - 180

if (anglediff <= 45 && anglediff>=-45) ....

The reason is that the difference in angles is facingAngle - angleOfTarget although due to wrapping effects, might be off by 360 degrees.

The add 180+360 then modulo 360 then subtract 180, effectively just converts everything to the range -180 to 180 degrees (by adding or subtracting 360 degrees).

Then you can check the angle difference easily, whether it is within -45 to 45 degrees.