Question

Atan2(y,x) will return a float between -pi and pi. I want to calculate the distance between two angles, but the non-continuity is throwing me off.

See this for better understanding.

I want to be able to calculate the distance between Angle 1 and Angle 2.

The whole point of this is to be able to create a cone from the center to a specified angle. Essentially I will be evaluating:

if(DistanceFromAngle1 < pi/4 [45°])
{
  Angle2 is part of cone
}

Answer 1

If by distance you mean the straight line joining the two interception points, you can calculate the distance by doing this:

SQRT( ( ABS|cos(A) - cos(B)| )^2 + ( ABS|sin(A) - sin(B)| )^2 )

SQRT = square root

ABS = Absolute value

If the distance is the angle, you calculate it by doing (pseudo-code)

var angle = ABS(A - B)
if(angle > pi) angle = 2*pi - angle
return angle