_rotation and easing problems

programming flash
1

hello all, it’s been a long time since i posted a question here but im really stuck on this one.

im trying to create a life sim which requires random motion. i thought id create a creature that moves around and turns in random directions. to make the turning smooth, i decided to ease the turning. this is where the problem starts. btw, here’s what i have in AS:

scrnW = scrnH=300;
mvSpd = 1;
randAng = function () {
	cir.ang += Math.random()*200-100;
};
rotate = function (spd) {
	cir._rotation -= (cir._rotation-cir.ang)/spd;
};
cir.onEnterFrame = function() {
	this._x += Math.cos(this._rotation*Math.PI/180)*mvSpd;
	this._y += Math.sin(this._rotation*Math.PI/180)*mvSpd;
	this._x = this._x>scrnW ? 0 : this._x<0 ? scrnW : this._x;
	this._y = this._y>scrnH ? 0 : this._y<0 ? scrnH : this._y;
};
setInterval(randAng, 5000);
setInterval(rotate, 20, 50);

when cir.ang becomes greater than 180 (lets say 200) then the thing tries to rotate to 200 but once it passes 180, it jumps back to -180 (_rotation has a range form -180 to 180) and it starts going in circles because it can never reach 200 degrees… how can i fix this i tried this code:

scrnW = scrnH=300;
mvSpd = 1;
randAng = function () {
	cir.ang += Math.random()*200-100;
};
rotate = function (spd) {
	rot = cir._rotation -= (cir._rotation-cir.ang)/spd;
//prevents cir.ang from going over 180 and under -180
	if (cir.ang>180) {
		cir.ang = 360-cir.ang;
	}
	if (cir.ang<-180) {
		cir.ang = 360+cir.ang;
	}
};
cir.onEnterFrame = function() {
	this._x += Math.cos(this._rotation*Math.PI/180)*mvSpd;
	this._y += Math.sin(this._rotation*Math.PI/180)*mvSpd;
	this._x = this._x>scrnW ? 0 : this._x<0 ? scrnW : this._x;
	this._y = this._y>scrnH ? 0 : this._y<0 ? scrnH : this._y;
};
setInterval(randAng, 2000);
setInterval(rotate, 20, 50);

but this just prevents it from completely turning all the way around, which is what im looking for…