{
  "stage":
  {
    "left":   0,
    "right":  0,
    "top":    0,
    "bottom": 0
  },

  "balls":
  [
    { "img":   "tux",
      "count": 20,
      "r":     { "@min": 25, "@max": 40 },
      "x":     { "@min": 0.2, "@max": 0.8, "@relative": "horizontal"},
      "y":     { "@min": 0.2, "@max": 0.8, "@relative": "vertical"},
      "vx":    { "@min": 100, "@max": 300, "@positive": 0.5},
      "vy":    { "@min": 100, "@max": 300, "@positive": 0.5}
    },
    { "img":   "owl",
      "count": 30,
      "r":     { "@min": 25, "@max": 35 },
      "x":     { "@min": 0.2, "@max": 0.8, "@relative": "horizontal"},
      "y":     { "@min": 0.2, "@max": 0.8, "@relative": "vertical"},
      "vx":    { "@min": 100, "@max": 300, "@positive": 0.5},
      "vy":    { "@min": 100, "@max": 300, "@positive": 0.5}
    }
  ]
}