function update()
    {
      var dt = 0.05; 
      
      if(savedMouseCoords != null && selectOffset != null)
      {
        blobColl.selectedBlobMoveTo(savedMouseCoords.x - selectOffset.x, 
          savedMouseCoords.y - selectOffset.y); 
      }
      
      blobColl.move(dt); 
      blobColl.sc(env); 
      blobColl.setForce(gravity); 
    }