Ball bounce résolu mais ne comprend pas...

Code :

package com

{

    import com.display.Ball;

    

    import flash.display.Graphics;

    import flash.display.MovieClip;

    import flash.display.Sprite;

    import flash.display.StageAlign;

    import flash.display.StageScaleMode;

    import flash.events.Event;

    import flash.events.MouseEvent;

    import flash.geom.Point;



    [SWF(width = "400", height = "300", frameRate = "60", backgroundColor = "#dddddd")]

    public class Main extends MovieClip

    {

        private var b1:Ball;

        private var b2:Ball;

        private var b3:Ball;

        private var b4:Ball;

        private var b5:Ball;

        private var testClip:Sprite;

        private const ANGLE_TOP_LEFT:int=135;

        private const ANGLE_BOTTOM_LEFT:int=-135;

        private const ANGLE_TOP_RIGHT:int=45;

        private const ANGLE_BOTTOM_RIGHT:int=-45;

        

        public function Main()

        {

            stage.align = StageAlign.TOP_LEFT;

            stage.scaleMode = StageScaleMode.NO_SCALE;

            trace("stageSize = " + getStageSize() + ", fps = " + stage.frameRate);

            drawlineGuides();

            addBalls();

            stage.addEventListener(Event.RESIZE,onStageResize);

        }

        private function addBalls():void{

            b1 = new Ball(500/2,250/2,10);

            addChild(b1);

            b1.color = 0x6666cc;

            b1.rota = 135;

            b1.drawBall();

            b1.move(5);    

            

            b2 = new Ball(100,100,10);

            addChild(b2);

            b2.color = 0xff9900;

            b2.rota = -110;

            b2.drawBall();

            b2.move(4);

            

            b3 = new Ball(50,80,10);

            addChild(b3);

            b3.color = 0xff0000;

            b3.rota = 60;

            b3.drawBall();

            b3.move(3);

            

            b4 = new Ball(75,20,10);

            addChild(b4);

            b4.color = 0x00aa00;

            b4.rota = 10;

            b4.drawBall();

            b4.move(4);

            

            b5 = new Ball(125,130,10);

            addChild(b5);

            b5.color = 0x8457a2;

            b5.rota = -45;

            b5.drawBall();

            b5.move(4);

            

            stage.addEventListener(MouseEvent.MOUSE_DOWN,b1.pauseResume);

            stage.addEventListener(MouseEvent.MOUSE_DOWN,b2.pauseResume);

            stage.addEventListener(MouseEvent.MOUSE_DOWN,b3.pauseResume);

            stage.addEventListener(MouseEvent.MOUSE_DOWN,b4.pauseResume);

            stage.addEventListener(MouseEvent.MOUSE_DOWN,b5.pauseResume);

        }

        private function rotate(e:Event):void{

            testClip.rotation = b2.rotation-45;

        }

        private function getStageSize():Point{

            var p:Point= new Point(stage.stageWidth,stage.stageHeight);

            return p;

        }

        private function drawlineGuides():void{

            var g:Graphics = this.graphics;

            g.clear();

            g.lineStyle(1,0x000000,1);

            g.moveTo(0,stage.stageHeight/2);

            g.lineTo(stage.stageWidth,stage.stageHeight/2);

            g.moveTo(stage.stageWidth/2,0);

            g.lineTo(stage.stageWidth/2,stage.stageHeight);

        }

        private function onStageResize(e:Event):void{

            drawlineGuides();

        }

    }

}

Code :

package com.display

{

    /* this import is optionnal

    if you want to run this class without the BongSound instance

    comment all lines where the var bSound is called

    */

    //import com.media.sound.BongSound;

    

    import flash.display.Graphics;

    import flash.display.Sprite;

    import flash.events.Event;

    import flash.events.MouseEvent;

    import flash.geom.Point;

    import flash.media.Sound;



    public class Ball extends Sprite

    {

        private var _radius:int;

        private var _rotation:Number;

        private var _color:int;

        private var _g:Graphics;

        private var _g2:Graphics;

        private var _speed:Number;

        private var speedx:Number;

        private var speedy:Number;

        public var rota:Number;

        private var smallCircle:Sprite;

        private var rendered:Boolean = false;

        public var paused:Boolean = false;

        private const ZERO:uint = 0;

        //private var bSound:BongSound;

        /**

         * Ball(posx:Number,posy:Number,radius:uint)<br/>

         * this constructor create an instance of a bouncing ball<br/>

         * the posx and posy must be included in the range of the defined stageWidth and stageHeight!<br/>

         * Otherwise, the ball will be placed in the stage range.

         */

        public function Ball(posx:Number,posy:Number,radius:uint)

        {

            //bSound = new BongSound();

            smallCircle = new Sprite();

            this.addChild(smallCircle);

            this._radius = radius;

            this.x = posx;

            this.y = posy;

            _g = this.graphics;

            _g2 = smallCircle.graphics;

        }

        private function checkStageSize():void{

            if(this.x + radius + speedx >= this.stage.stageWidth){

                this.x = this.stage.stageWidth - this.width;

            }

            if(this.y + radius + speedy >= this.stage.stageHeight){

                this.y = this.stage.stageHeight - this.height;

            }

            if(this.x - radius + speedx <= ZERO){

                this.x = this.width;

            }

            if(this.y - radius + speedy <= ZERO){

                this.y = this.height;

            }

        }

        public function get speed():Number

        {

            return _speed;

        }

        public function set speed(value:Number):void

        {

            _speed = value;

        }

        public function get color():int

        {

            return _color;

        }

        public function set color(value:int):void

        {

            _color = value;

        }

        public function get radius():int

        {

            return _radius;

        }

        public function set radius(value:int):void

        {

            _radius = value;

        }

        /**

         * drawBall()<br/>

         * this function draws the main Ball Object

         */

        public function drawBall():void

        {

            _g.clear();

            _g.lineStyle(1,0x666666,1);

            _g.beginFill(_color,1);

            _g.drawCircle(0,0,this._radius);

            _g.endFill();

            _g.lineStyle(1,0x666666,1);

            _g.beginFill(0xffffff,1);

            _g.endFill();

        }

        /**

         * drawPoint()<br/>

         * this function draws the Point Object wich is placed in the direction/rotation of the main Ball instance.

         */

        public function drawPoint():void{

            _g2.clear();

            _g2.lineStyle(1,0x666666,1);

            _g2.beginFill(0xffffff,1);

            _g2.drawCircle(ZERO, ZERO, this._radius/2);

            smallCircle.x = Math.sin(deg2rad(rota+90))*this.radius/2;

            smallCircle.y = Math.cos(deg2rad(rota+90))*this.radius/2;

            _g2.endFill();

        }

        /**

         * move(speed:Number):void<br/>

         * this function set the speed and makes the Ball move.<br/>

         * The displace function is called when an ENTER_FRAME event is triggered.

         */

        public function move(speed:Number):void{

            this.speed = speed;

            this.addEventListener(Event.ENTER_FRAME,displace);

        }

        /**

         * getRota():Number<br/>

         * this function returns the rotation of the Ball instance.<br/>

         * the rotation is returned in degrees.

         */

        public function getRota():Number{

            return rad2deg(Math.atan2(speedy,speedx));

        }

        /**

         * pauseResume(e:MouseEvent):void

         * Pause or resume movement.

         */

        public function pauseResume(e:MouseEvent):void{

            switch(paused){

                case false:

                    this.removeEventListener(Event.ENTER_FRAME,displace);

                    paused = true;

                    break;

                case true:

                    this.addEventListener(Event.ENTER_FRAME,displace);

                    paused = false;

                    break;

            }

        }

        /**

         * checkBounds():void<br/>

         * <p>

         * this function plays a Sound when the Ball instance hit the bounds.<br/>

         * the rota variable is updated (even if the rotation of the Ball instance don't change).<br/>

         * If the stage is resized, a call to checkStageSize() set the positions x & y in the bounds of the Stage.

         * </p>

         * @see checkStageSize()

         */

        private function checkBounds():void{

            if(this.x + radius + speedx >= this.stage.stageWidth){

                //bSound.play();

                rota = rad2deg(Math.atan2(-speedy,-speedx));

            }

            if(this.y + radius + speedy >= this.stage.stageHeight){

                //bSound.play();

                rota = rad2deg(Math.atan2(speedy,speedx));

            }

            if(this.x - radius + speedx <= ZERO){

                //bSound.play();

                rota = rad2deg(Math.atan2(-speedy,-speedx));

            }

            if(this.y - radius + speedy <= ZERO){

                //bSound.play();

                rota = rad2deg(Math.atan2(speedy,speedx));

            }

            checkStageSize();

        }

        /**

         * <p>

         * displace(e:Event):void

         * displace the ball and calls drawPoint to place the sub-Sprite depending of the "rotation" of the Ball instance.</p>

         * @see #drawPoint()

         * @see #checkBounds()

         */

        private function displace(e:Event):void{

            checkBounds();

            speedx = Math.sin(deg2rad(rota+90))*speed;

            speedy = Math.cos(deg2rad(rota+90))*speed;

            this.x += speedx;

            this.y += speedy;

            drawPoint();

        }

        public function deg2rad(value:Number):Number{

            return value/180*Math.PI;

        }

        public function rad2deg(value:Number):Number{

            return value*180/Math.PI;

        }



    }

}