import flash.display.Sprite;

import flash.display.Graphics;

import flash.events.*;

 

function getBall(radius:Number):Sprite {

        var sprite:Sprite = new Sprite();

        var gr:Graphics = sprite.graphics;

        gr.lineStyle(1,0);

        gr.beginFill(0xFF0000,0.5);

        gr.drawCircle(0,0,radius);

        gr.endFill();

        return sprite;

}

 

var radius:int = 20;

var ball_1:Sprite = getBall(radius);

var ball_2:Sprite = getBall(radius);

 

addChild(ball_1);

addChild(ball_2);

 

ball_1.x = ball_1.y = 250;

ball_2.x = ball_2.y = 300;

 

ball_1.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler);

ball_1.addEventListener(Event.ENTER_FRAME, updateBallPosition);

 

var draging:Boolean = false;

var startDragX:Number;

var startDragY:Number;

var ballVx:Number = 0;

var ballVy:Number = 0;

var ballFriction = 0.9;// or bounce ?

 

function mouseDownHandler(e:MouseEvent):void {

        draging = true;

        ballVx = 0;

        ballVy = 0;

        startDragX = ball_1.mouseX;

        startDragY = ball_1.mouseY;

        stage.addEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);

        stage.addEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);

}

function mouseMoveHandler(e:MouseEvent):void {

        ball_1.x = stage.mouseX - startDragX;

        ball_1.y = stage.mouseY - startDragY;

        e.updateAfterEvent();

}

function mouseUpHandler(e:MouseEvent):void {

        draging = false;

        stage.removeEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);

        stage.removeEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);

        checkCollision();

}

function checkCollision():void {

        var dx:Number = ball_1.x - ball_2.x;

        var dy:Number = ball_1.y - ball_2.y;

        var dist:Number = Math.sqrt(dx * dx + dy * dy);

        var collisionDepth:Number = radius * 2 - dist;

        if (collisionDepth > 0) {

                var collisionAngle:Number = Math.atan2(dy,dx);// in radians

                ballVx = collisionDepth * Math.cos(collisionAngle);

                ballVy = collisionDepth * Math.sin(collisionAngle);

        }

}

 

function updateBallPosition(e:Event):void {

        if (draging) {

                return;

        }

        ball_1.x +=  ballVx;

        ball_1.y +=  ballVy;

        ballVx *=  ballFriction;

        ballVy *=  ballFriction;

}