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-ch18-RotateXY.ax

animation-ch18-RotateXY.ax [swf] [flash] flex 


  //# package
  package {
   import flash.display.Sprite;
   import flash.display.StageAlign;
   import flash.display.StageScaleMode;
   import flash.events.Event;

class


   public class @ax-animation-ch18-RotateXY extends Sprite
   {
    private var balls:Array;
    private var numBalls:uint = 50;
    private var fl:Number = 250;
    private var vpX:Number = stage.stageWidth / 2;
    private var vpY:Number = stage.stageHeight / 2;

constructor


    public function @ax-animation-ch18-RotateXY()
    {
     init();
    }

init(s)


    private function init():void
    {
     stage.align = StageAlign.TOP_LEFT;
     stage.scaleMode = StageScaleMode.NO_SCALE;
     
     balls = new Array();

initialize ball(s) / enterFrame


     for(var i:uint = 0; i < numBalls; i++)
     {
      var ball:animation_ch18_Ball3D = new animation_ch18_Ball3D(15);
      balls.push(ball);
      ball.xpos = Math.random() * 200 - 100;
      ball.ypos = Math.random() * 200 - 100;
      ball.zpos = Math.random() * 200 - 100;
      addChild(ball);
     }
     addEventListener(Event.ENTER_FRAME, onEnterFrame);
    }

animation handler / frame(s)


    
    private function onEnterFrame(event:Event):void
    {
     var angleX:Number = (mouseY - vpY) * .001;
     var angleY:Number = (mouseX - vpX) * .001;
     for(var i:uint = 0; i < numBalls; i++)
     {
      var ball:animation_ch18_Ball3D = balls[i];
      rotateX(ball, angleX);
      rotateY(ball, angleY);
      doPerspective(ball);
     }
     sortZ();
    }

rotate X


    
    private function rotateX(ball:animation_ch18_Ball3D, angleX:Number):void
    {
     var position:Array = [ball.xpos, ball.ypos, ball.zpos];
     
     var sin:Number = Math.sin(angleX);
     var cos:Number = Math.cos(angleX);
     var xRotMatrix:Array = new Array();
     xRotMatrix[0] = [1,    0,   0];
     xRotMatrix[1] = [0,  cos, sin];
     xRotMatrix[2] = [0, -sin, cos]
     
     var result:Array = matrixMultiply(position, xRotMatrix);
     ball.xpos = result[0];
     ball.ypos = result[1];
     ball.zpos = result[2];
    }

rotate Y


    
    private function rotateY(ball:animation_ch18_Ball3D, angleY:Number):void
    {
     var position:Array = [ball.xpos, ball.ypos, ball.zpos];
     
     var sin:Number = Math.sin(angleY);
     var cos:Number = Math.cos(angleY);
     var yRotMatrix:Array = new Array();
     yRotMatrix[0] = [ cos, 0, sin];
     yRotMatrix[1] = [   0, 1,   0];
     yRotMatrix[2] = [-sin, 0, cos]
     
     var result:Array = matrixMultiply(position, yRotMatrix);
     ball.xpos = result[0];
     ball.ypos = result[1];
     ball.zpos = result[2];
    }

matrix multiplication


    
    private function matrixMultiply(matrixA:Array, matrixB:Array):Array
    {
     var result:Array = new Array();
     result[0] = matrixA[0] * matrixB[0][0] + 
        matrixA[1] * matrixB[1][0] +
        matrixA[2] * matrixB[2][0];
     
     result[1] = matrixA[0] * matrixB[0][1] +
        matrixA[1] * matrixB[1][1] +
        matrixA[2] * matrixB[2][1];
     
     result[2] = matrixA[0] * matrixB[0][2] +
        matrixA[1] * matrixB[1][2] +
        matrixA[2] * matrixB[2][2];
     return result;
    }

perspective / trick(s) = scaling


    
    private function doPerspective(ball:animation_ch18_Ball3D):void
    {   
     if(ball.zpos > -fl)
     {
      var scale:Number = fl / (fl + ball.zpos);
      ball.scaleX = ball.scaleY = scale;
      ball.x = vpX + ball.xpos * scale;
      ball.y = vpY + ball.ypos * scale;
      ball.visible = true;
     }
     else
     {
      ball.visible = false;
     }
    }

do not forget to sort-Z


    private function sortZ():void
    {
     balls.sortOn("zpos", Array.DESCENDING | Array.NUMERIC);
     for(var i:uint = 0; i < numBalls; i++)
     {
      var ball:animation_ch18_Ball3D = balls[i];
      setChildIndex(ball, i);
     }
    }
   }
  }
[] 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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