package {
          import flash.display.Sprite;
          import flash.display.StageAlign;
          import flash.display.StageScaleMode;
          import flash.events.Event;
          import flash.geom.Rectangle;
  
          public class @ax-lib-flex-animation-code-06-Square extends Sprite
          {
                  private var _points:Array;
                  private var _sticks:Array;
                  private var _stageRect:Rectangle;
                  
                  public function @ax-lib-flex-animation-code-06-Square()
                  {
                          stage.align = StageAlign.TOP_LEFT;
                          stage.scaleMode = StageScaleMode.NO_SCALE;
                          _stageRect = new Rectangle(0, 0, stage.stageWidth, stage.stageHeight);
                           
                          _points = new Array();
                          _sticks = new Array();
                           
                          var pointA:VerletPoint = makePoint(100, 100);
                          pointA.vx = 10;
                          var pointB:VerletPoint = makePoint(200, 100);
                          var pointC:VerletPoint = makePoint(200, 200);
                          var pointD:VerletPoint = makePoint(100, 200);
                          
                          makeStick(pointA, pointB);
                          makeStick(pointB, pointC);
                          makeStick(pointC, pointD);
                          makeStick(pointD, pointA);
                          makeStick(pointA, pointC);
                          
                          addEventListener(Event.ENTER_FRAME, onEnterFrame);
                  }
                  
                  private function onEnterFrame(event:Event):void
                  {
                          updatePoints();
                          
                          for(var i:int = 0; i < 1; i++)
                          {
                                  constrainPoints();
                                  updateSticks();
                          }
                          
                          graphics.clear();
                          renderPoints();
                          renderSticks();
                  }
                  
                  private function makePoint(xpos:Number, ypos:Number):VerletPoint
                  {
                          var point:VerletPoint = new VerletPoint(xpos, ypos);
                          _points.push(point);
                          return point;
                  }
                  
                  private function makeStick(pointA:VerletPoint, pointB:VerletPoint, length:Number = -1):VerletStick
                  {
                          var stick:VerletStick = new VerletStick(pointA, pointB, length);
                          _sticks.push(stick);
                          return stick;
                  }
                  
                  private function updatePoints():void
                  {
                          for(var i:int = 0; i < _points.length; i++)
                          {
                                  var point:VerletPoint = _points[i] as VerletPoint;
                                  point.y += .5;
                                  point.update();
                          }
                  }
                  
                  private function constrainPoints():void
                  {
                          for(var i:int = 0; i < _points.length; i++)
                          {
                                  var point:VerletPoint = _points[i] as VerletPoint;
                                  point.constrain(_stageRect);
                          }
                  }
                  
                  private function updateSticks():void
                  {
                          for(var i:int = 0; i < _sticks.length; i++)
                          {
                                  var stick:VerletStick = _sticks[i] as VerletStick;
                                  stick.update();
                          } 
                  }
                  
                  private function renderPoints():void
                  {
                          for(var i:int = 0; i < _points.length; i++)
                          {
                                  var point:VerletPoint = _points[i] as VerletPoint;
                                  point.render(graphics);
                          }
                  }
                  
                  private function renderSticks():void
                  {
                          for(var i:int = 0; i < _sticks.length; i++)
                          {
                                  var stick:VerletStick = _sticks[i] as VerletStick;
                                  stick.render(graphics);
                          }
                  }
          }
  }