package 
  {
          public class @ax-graphic-flex-animation-bubbles-Base {
                  internal var model : Object = {
                          "walls" : {"left":0, "top":0, "right": 500, "bottom": 300},
                          "elastity" : -0.2,
                          "ballRadius" : 26,
                          "maxSpeed" : 3.0 
                  };
  
                  public function @ax-graphic-flex-animation-bubbles-Base() {
                          // default provisioning
                          this._x = (model.walls.right - model.walls.left - 2*model.ballRadius)*Math.random(); 
                          this._y = (model.walls.bottom - model.walls.top - 2*model.ballRadius)*Math.random();
                          this._vx = 2*model.maxSpeed*Math.random() - model.maxSpeed;
                          this._vy = 2*model.maxSpeed*Math.random() - model.maxSpeed;
                          this._r = model.ballRadius; // d = 52 px
                          this._d = 2*this._r;
                          this._d2 = this._d*this._d;
                  }
                  protected var _x:Number = 0;
                  protected var _y:Number = 0;
                  protected var _vx:Number = 0;
                  protected var _vy:Number = 0;
                  protected var _r:Number = 26;
                  protected var _d:Number;
                  protected var _d2:Number;                
                  
                  public function move() : void {
                          this._x += this._vx;
                          this._y += this._vy;
                          // walls collisons
                          
                          // left
                          if (this._x < model.walls.left && this._vx<0) {
                                  //this._vx += (this._x - walls.left)*elastity;
                                  this._vx = -this._vx;
                          }
                          // top
                          if (this._y < model.walls.top && this._vy<0) {
                                  //this._vy += (this._y - walls.top)*elastity;
                                  this._vy = -this._vy;
                          }
                          // left
                          if (this._x > model.walls.right - this._d && this._vx>0) {
                                  //this._vx += (this._x - walls.right + this._d)*elastity;
                                  this._vx = -this._vx;
                          }
                          // top
                          if (this._y > model.walls.bottom - this._d && this._vy>0) {
                                  //this._vy += (this._y - walls.bottom + this._d)*elastity;
                                  this._vy = -this._vy;
                          }
                  }
                  
                  public function doCollide (b : @ax-graphic-flex-animation-bubbles-Base) : Boolean {
                          // calculate some vectors 
                          var dx : Number = this._x - b._x;
                          var dy : Number = this._y - b._y;
                          var dvx : Number = this._vx - b._vx;
                          var dvy : Number = this._vy - b._vy;        
                          var distance2 : Number = dx*dx + dy*dy;
                                  
                          if (Math.abs(dx) > this._d || Math.abs(dy) > this._d) 
                                  return false;
                          if (distance2 > this._d2)
                                  return false;
                          
                          // make absolutely elastic collision
                          var mag : Number = dvx*dx + dvy*dy;
                          
                          // test that balls move towards each other        
                          if (mag > 0) 
                                  return false;
                  
                          mag /= distance2;
                          
                          var delta_vx : Number = dx*mag;
                          var delta_vy : Number = dy*mag;
                          
                          this._vx -= delta_vx;
                          this._vy -= delta_vy;
                          
                          b._vx += delta_vx;
                          b._vy += delta_vy;
                                  
                          return true;
                  }
          }
  
  }