Question

This system is really confusing me. I’m rotating a turret to face an enemy sprite, I get the angle in radians with:

float angleRadians = atanf(yDifference / xDifference);
float angleDegrees = CC_RADIANS_TO_DEGREES(angleRadians);

That’s cool, now I put the enemy in several positions to see how it plotted the angles in DEGREES:

T = Turret

-45      90      45

-0        T       0

45       -90     -45

The angle for an enemy top-right of the turret is going to be the same as the angle for an enemy bottom-left, thus I’d have to have some form of condition to distinguish the 2. That wouldn’t be hard except for the fact that cocos2d’s rotational angles work like this:

45      90        135

0       T       +/-180

-45    -90       -135 

What do I have to do to convert the angle I calculated at the start to correctly rotate the turret with this system above?

Answer 1

If you use:

float angleRadians = atan2f(yDifference, xDifference);

this should return an angle in radians which is in the range [-pi, pi].
This should fix yoUr problem.