png2asset: -source_tileset doesn't play nice with -use_structs about gbdk-2020 HOT 2 OPEN

Looks like it may be (mostly) working as designed right now, but in a way which doesn't meet the additional expectations of ZGB.

When -source_tileset is specified it only writes tile data/palettes/etc out if new entries are found which are not present in the source tileset.

However ZGB seems to expect:

• A ___tiles_info {} struct to be generated regardless of whether any new tiles are found
• And probably the same for ___tiles[], ____tile_pals[] and ___palettes[] regardless of whether they're empty or not

With the version in the develop branch (and CI) if you create a single novel tile in the map you can see that it begins to export some of the missing arrays.

It is probably not hard to force output of those entries for even if they are empty when -use_structs is present for ZGB. However:

• It's not clear without testing whether empty arrays would be ok or might cause a crash
• That still wouldn't include the source tileset data, so that would still have to get loaded. Did you envision having that data be included in the output, or manually loading it on your own from a separate file?

Going to @Zal0 into this since he may have some opinions about the right way to support this.

from gbdk-2020.