Stores the results of scene queries. This can be passed around to multiple SQAccelerators and is responsible for sorting the results and pruning based on blocking. IncFlushCount / DecFlushCount is used to ensure any final sort / pruning operation is done when all SQAccelerators are finished. If you are passing this into multiple accelerators you should call IncFlushCount / DecFlushCount yourself as otherwise each accelerator will trigger its own sort / prune.