[AS3] first person shooter game, Bullet dirrection towords aim (cursor)

programming
1

Hello there.
I have started a FPS game with CS5.5.
So far i have done a background, the aim which moves with the mouse and the gun which also moves with the mouse but only on X axis.

But now i have no idea how to start with bullet going from the Gun to the Aim (mouse).
I know its some trigonometry involved though. I have tried something but only succeded in making the bullets going from the gun at some degrees up.

Can anyone help me on this?

This is the code so far :



import flash.events.KeyboardEvent;
import flash.events.Event;
import flash.display.MovieClip;
import flash.utils.Timer;
import flash.display.Sprite;
import fl.motion.DynamicMatrix;
import flashx.textLayout.accessibility.TextAccImpl;
import flash.display.Sprite;
import flash.display.Shape;
import flash.ui.Mouse;
import flash.events.MouseEvent;






stage.addEventListener(MouseEvent.MOUSE_MOVE, aiming);
Mouse.hide();

function aiming(event:MouseEvent):void
{
    aim.x=mouseX;
    aim.y=mouseY;
    gun1.x=mouseX+225;
    if(aim.x<0)
    {
        aim.x=0;
    }
    if(aim.x>800)
    {
        aim.x=800;
    }
    if(aim.y<0)
    {
        aim.y=0;
    }
    if(aim.y>600)
    {
        aim.y=600;
    }
    if(gun1.x>850)
    {
        gun1.x=850;
    }
    if(gun1.x<110)
    {
        gun1.x=110;
    }
}




stage.addEventListener(MouseEvent.MOUSE_DOWN,pressShoot); 

function pressShoot(event:Event) 
{
    trace("mouse is pressed");
    gun1.gotoAndPlay(2);
}

Thanks in advance for any help.