Function ResourceInteractiveLoader.poll

Polls the loading operation, i.e. loads a data chunk up to the next stage. Returns constant OK if the poll is successful but the load operation has not finished yet (intermediate stage). This means poll will have to be called again until the last stage is completed. Returns constant ERR_FILE_EOF if the load operation has completed successfully. The loaded resource can be obtained by calling getResource. Returns another error code if the poll has failed.