math for rotated dragging

[florio]

Hi all,

this math isn't working well. I'm using it for a rotated drag and drop (of a tone arm on a vinyl, a kind of abstract turntable simulation). Right now it just moves a bit in the middle of the vinyl (values between
21 and 36, is this degree or what unit is this?), but it should move between the two edges. The problem is that I don't know enough about trigonometry functions. Therefore I can't optimize the math for envisaged behaviour.
Does anybody have an idea/tip how I can get a bit more control on the math and its effect? (maybe with more trace functions)

Thanks in advance.
Best,

Florian

code in actionscript document:

package mathfiles.com.flashcreations.utils {
    
    public class MathExtra {


    public static function randomBetween(a:Number, b:Number):Number {
        return (a + Math.floor(Math.random()*(b-a+1)));
    }   

    
    public static function rotation2(dx:Number, dy:Number):Number {
        return Math.atan2(dy, dx) * (45/Math.PI);
    }
}
}

code in frame:

import mathfiles.com.flashcreations.utils.MathExtra;
import flash.media.Sound;
import flash.media.SoundChannel;
import flash.events.Event;
import flash.net.URLRequest;


var trk1:Sound = new Sound();
var trkChannel1:SoundChannel;
var req:URLRequest = new URLRequest("Sound/aleatoric inspiration_2.mp3");
trk1.load(req);

stage.addEventListener(MouseEvent.MOUSE_DOWN, pressHandler);

function pressHandler(e:Event):void {
    stage.addEventListener(MouseEvent.MOUSE_MOVE, moveHandler);
    stage.addEventListener(MouseEvent.MOUSE_UP, upHandler);
    trkChannel1.stop();
}
function moveHandler(e:Event):void {
    if (mc_area.hitTestPoint(mouseX,mouseY,true)) {
        mc_arm.rotation=MathExtra.rotation2(mouseX-mc_arm.x,mouseY-mc_arm.y);
    }
//  trace(mc_arm.rotation);
}
function upHandler(e:Event):void {
    stage.removeEventListener(MouseEvent.MOUSE_UP, upHandler);
    stage.removeEventListener(MouseEvent.MOUSE_MOVE, moveHandler);
    var starts:Number=(((mc_arm.rotation-21)/17)*trk1.length);
    trkChannel1 = trk1.play(starts);
//  trace(starts);
}

[skewq]

from the looks of it the problem might be - 180/Pi not 45/Pi