import flash.display.Graphics;

 

var temp:Sprite = new Sprite();

addChild(temp);

var areaRadius:int = 180;

var areaCenterX:int = 275;

var areaCenterY:int = 200;

var ballRadius = 20;

var ball:Object = {};

ball.x = areaCenterX + 90;

ball.y = areaCenterY;

 

var ballSpeed:Number = 20;

var randomAngle:Number = 90 * Math.PI / 180;

ball.vx = Math.cos(randomAngle) * ballSpeed;

ball.vy = Math.sin(randomAngle) * ballSpeed;

 

var hitDistance:int = areaRadius - ballRadius;

 

var g:Graphics = this.graphics;

g.lineStyle(1,0xFF0000,1);

g.drawCircle(areaCenterX,areaCenterY,areaRadius);

 

var ballSprite:Sprite = new Sprite();

ballSprite.graphics.lineStyle(1,0x00FF00,1);

ballSprite.graphics.drawCircle(0,0,ballRadius);

 

 

addChild(ballSprite);

 

function step(e:Event = null):void {

 

        var newX:Number = ball.x + ball.vx;

        var newY:Number = ball.y + ball.vy;

 

        var dx:Number = (newX - areaCenterX);

        var dy:Number = (newY - areaCenterY);

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

        if (distance >= hitDistance) {

 

                var ballAngle:Number = Math.atan2(ball.vy,ball.vx);

                var hitX:Number = hitDistance * Math.cos(ballAngle);

                var hitY:Number = hitDistance * Math.sin(ballAngle);

                var hitAngle:Number = Math.atan2(newY - areaCenterY,newX - areaCenterX);

                var bounceAngle:Number = ballAngle+2* (hitAngle - ballAngle);

 

                temp.graphics.clear();

                temp.graphics.lineStyle(1,0xFF00FF,1);

                temp.graphics.moveTo(newX, newY);

                temp.graphics.lineTo(newX + Math.cos(bounceAngle) * 200, newY + Math.sin(bounceAngle) * 200);

 

                ball.vx = ballSpeed *  -  Math.cos(bounceAngle);

                ball.vy = ballSpeed *  -  Math.sin(bounceAngle);

        }

 

        ball.x +=  ball.vx;

        ball.y +=  ball.vy;

        //

        ballSprite.x = ball.x;

        ballSprite.y = ball.y;

}

step();

addEventListener(Event.ENTER_FRAME, step);