Hello, i am currently working on custom format for resource packs for game. The packs contains assests, which are compressed. Currently i am facing the problem that if the assets outside the pack and inside it are the same, then the pack should not be rebuit.

The easiest solution that i could think of is to save the timestamps of the files (last write) inside the pack. When starting to build the pack, the last write time of each file will be compared with the timestamp in the pack and it will be determined if there is change in atleast one file. Then if there is, the pack is rebuilt.

Is there a better solution of the problem?

I store cache of pre-processed assets in "hidden" subdirectory.

Also there's sqlite db file in that dir, storing source file hashes and additional attributes.

When pack is rebuilt, for every added file I calculate hash and check if there's cached blob with that hash.

If there's such file in cache - it will be added to pack as is. If there's no file in cache, then asset will be pre-processed, compressed and cached.

In that way pack is rebuilt very quickly, as only changed resources will be actually processed.

And there's neat side effect - multiple identical assets will refer to same blob in pack.

I store cache of pre-processed assets in "hidden" subdirectory.

Also there's sqlite db file in that dir, storing source file hashes and additional attributes.

When pack is rebuilt, for every added file I calculate hash and check if there's cached blob with that hash.

If there's such file in cache - it will be added to pack as is. If there's no file in cache, then asset will be pre-processed, compressed and cached.

In that way pack is rebuilt very quickly, as only changed resources will be actually processed.

And there's neat side effect - multiple identical assets will refer to same blob in pack.

Thank you very much, your answer was very helpful.

CRC32 the file before compressing, keep the result in the package. If CRC32(new) == CRC32(old); ignore