topical media & game development
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

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animation-ch10-MultiAngleBounce.ax

animation-ch10-MultiAngleBounce.ax [swf] [flash] flex 


  package
  {
   import flash.display.Sprite;
   import flash.events.Event;
   import flash.display.StageScaleMode;
   import flash.display.StageAlign;
   import flash.geom.Rectangle;
  
   public class @ax-animation-ch10-MultiAngleBounce extends Sprite
   {
    private var ball:animation_ch10_Ball;
    private var lines:Array;
    private var numLines:uint = 5;
    private var gravity:Number = 0.3;
    private var bounce:Number = -0.6;
    
    public function @ax-animation-ch10-MultiAngleBounce()
    {
     init();
    }

init(s) 


    private function init():void
    {
     stage.scaleMode = StageScaleMode.NO_SCALE;
     stage.align = StageAlign.TOP_LEFT;
     ball = new animation_ch10_Ball(20);
     addChild(ball);
     ball.x = 100;
     ball.y = 50;
     
     // create five lines
     lines = new Array();
     for(var i:uint = 0; i < numLines; i++)
     {
      var line:Sprite = new Sprite();
      line.graphics.lineStyle(1);
      line.graphics.moveTo(-50, 0)
      line.graphics.lineTo(50, 0);
      addChild(line);
      lines.push(line);
     }

position and rotate them


     lines[0].x = 100;
     lines[0].y = 100;
     lines[0].rotation = 30;
     
     lines[1].x = 100;
     lines[1].y = 230;
     lines[1].rotation = 45;
     
     lines[2].x = 250;
     lines[2].y = 180;
     lines[2].rotation = -30;
     
     lines[3].x = 150;
     lines[3].y = 330;
     lines[3].rotation = 10;
     
     lines[4].x = 230;
     lines[4].y = 250;
     lines[4].rotation = -30;
     
     addEventListener(Event.ENTER_FRAME, onEnterFrame);
    }

frame(s) 


    private function onEnterFrame(event:Event):void
    {
     // normal motion code
     ball.vy += gravity;
     ball.x += ball.vx;
     ball.y += ball.vy;

bounce off ceiling, floor and walls


     if(ball.x + ball.radius > stage.stageWidth)
     {
      ball.x = stage.stageWidth - ball.radius;
      ball.vx *= bounce;
     }
     else if(ball.x - ball.radius < 0)
     {
      ball.x = ball.radius;
      ball.vx *= bounce;
     }
     if(ball.y + ball.radius > stage.stageHeight)
     {
      ball.y = stage.stageHeight - ball.radius;
      ball.vy *= bounce;
     }
     else if(ball.y - ball.radius < 0)
     {
      ball.y = ball.radius;
      ball.vy *= bounce;
     }
     
     // check each line
     for(var i:uint = 0; i < numLines; i++)
     {
      checkLine(lines[i]);
     }
    }

check(s) 


    private function checkLine(line:Sprite):void
    {
     // get the bounding box of the line
     var bounds:Rectangle = line.getBounds(this);
     if(ball.x > bounds.left && ball.x < bounds.right)
     {
      
      // get angle, sine and cosine
      var angle:Number = line.rotation * Math.PI / 180;
      var cos:Number = Math.cos(angle);
      var sin:Number = Math.sin(angle);
      
      // get position of ball, relative to line
      var x1:Number = ball.x - line.x;
      var y1:Number = ball.y - line.y;

rotation(s)


      // rotate coordinates
      var y2:Number = cos * y1 - sin * x1;
      
      // rotate velocity
      var vy1:Number = cos * ball.vy - sin * ball.vx;
      
      // perform bounce with rotated values
      if(y2 > -ball.height / 2 && y2 < vy1)
      {
       // rotate coordinates
       var x2:Number = cos * x1 + sin * y1;
       
       // rotate velocity
       var vx1:Number = cos * ball.vx + sin * ball.vy;
      
       y2 = -ball.height / 2;
       vy1 *= bounce;

rotate everything back;


       x1 = cos * x2 - sin * y2;
       y1 = cos * y2 + sin * x2;
       ball.vx = cos * vx1 - sin * vy1;
       ball.vy = cos * vy1 + sin * vx1;
       ball.x = line.x + x1;
       ball.y = line.y + y1;
      }
     }
    }
   }
  }
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

(C) Æliens 04/09/2009

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