As3: Math, I'm too stupid for this. (trigonometry) - actionscript-3

Question

Okay, so I made some ai where a guard is following my character.
I am using this code:
private function getDegrees(radians:Number):Number
{
//return Math.floor(radians/(Math.PI/180));
return radians / 0.01745 | 0;
}
private function getRadians(delta_x:Number, delta_y:Number):Number
{
var r:Number = Math.atan2(delta_y, delta_x);
if (delta_y < 0)
{
//r += (2 * Math.PI);
r += 6.283;
}
return r;
}
And then in the loop
if(isShooting)
{
// calculate rotation based on mouse X & Y
_dx = this.x - _root.assassin.x;
_dy = this.y - _root.assassin.y;
// which way to rotate
_rotateTo = getDegrees(getRadians(_dx, _dy));
// keep rotation positive, between 0 and 360 degrees
if (_rotateTo > this.rotation + 180) _rotateTo -= 360;
if (_rotateTo < this.rotation - 180) _rotateTo += 360;
// ease rotation
_trueRotation = (_rotateTo - this.rotation) / _rotateSpeedMax;
// update rotation
this.rotation += _trueRotation;
gotoAndStop(5);
isWalking = false;
isStanding = false;
}
The thing is, the guard rotates weirdly, it's as if he isn't looking at the player. It's as if the player is somewhere else. Dunno, it just doesn't work.. I have no idea what is wrong with the code!

Answer 1

You should just compute the relative angle
_rotateTo = getDegrees(getRadians(_dx, _dy));
_trueRotation = (_rotateTo - this.rotation) / _rotateSpeedMax;
then normalize this to be as close to zero as possible
_trueRotation = (_trueRotation+900) %360 - 180;
and then cut this to the maximal rotation per step
_trueRotation = max(_trueRotation,_rotateSpeedMax* _timestep);
_trueRotation = min(_trueRotation,-_rotateSpeedMax*_timestep);
and use this then to update the forward direction
this.rotation += _trueRotation;
Speed usually is change per time, so there should be a multiplication with some time step for semantic consistency. Of course, you may have the time step equal to 1, or rotateSpeedMax is really a rotateMaxAngle (per step), then the multiplication with timestep can be removed.

Answer 2

To keep the rotation positive you should use modulus 360 like below for readability and (code) simplicity until and unless it's a clear performance issue: (I think this is right for AC3, just looked it up online quick)
_rotateTo = _rotateTo % 360;
The other possible issue is with how you define _dx and _dy. I'm guessing that the assassin is facing in the opposite direction as intended. The fix is to useI'm thinking it should either be:
_dx = _root.assassin.x - this.x;
_dy = _root.assassin.y - this.y;