private void finish() {
   for (int i = 0; i < scratchFBO.length; i++) {
     if (scratchFBO[i] != null) {
       scratchFBO[i].delete();
       scratchFBO[i] = null;
     }
   }
   if (itemsFBO != null) {
     itemsFBO.delete();
     itemsFBO = null;
   }
   itemFrames.clear();
   layers.clear();
   ok = false;
 }