void AddSelectedGlobalLights(Object[] lights)
 {
     for (int i = 0; i < lights.Length; ++i)
     {
         Light2D light = lights[i] as Light2D;
         if (light != null && light.lightType == Light2D.LightType.Global)
         {
             Light2D.AddGlobalLight(light);
         }
     }
 }