package
  {
          import flash.display.Graphics;
          
          public class @ax-lib-flex-animation-code-06-VerletStick
          {
                  private var _pointA:VerletPoint;
                  private var _pointB:VerletPoint;
                  private var _length:Number;
                  
                  public function @ax-lib-flex-animation-code-06-VerletStick(pointA:VerletPoint, pointB:VerletPoint, length:Number = -1)
                  {
                          _pointA = pointA;
                          _pointB = pointB;
                          if(length == -1)
                          {
                                  var dx:Number = _pointA.x - _pointB.x;
                                  var dy:Number = _pointA.y - _pointB.y;
                                  _length = Math.sqrt(dx * dx + dy * dy);
                          }
                          else
                          {
                                  _length = length;
                          }
                  }
                  
                  public function update():void
                  {
                          var dx:Number = _pointB.x - _pointA.x;
                          var dy:Number = _pointB.y - _pointA.y;
                          var dist:Number = Math.sqrt(dx * dx + dy * dy);
                          var diff:Number = _length - dist;
                          var offsetX:Number = (diff * dx / dist) / 2;
                          var offsetY:Number = (diff * dy / dist) / 2;
                          _pointA.x -= offsetX;
                          _pointA.y -= offsetY;
                          _pointB.x += offsetX;
                          _pointB.y += offsetY;
                  }
                  
                  public function render(g:Graphics):void
                  {
                          g.lineStyle(0);
                          g.moveTo(_pointA.x, _pointA.y);
                          g.lineTo(_pointB.x, _pointB.y);
                  }
          }
  }