public double getContentPriority(Content c) {
   if (DirectContent.class.equals(c.getClass())) {
     return 0.0;
   }
   if (CenteredAndScaledContent.class.equals(c.getClass())) {
     return 1.0;
   }
   if (TerrainAlignedContent.class.equals(c.getClass())) {
     return 2.0;
   }
   return 10.0;
 }