Technical question: what are DIF files for?

[Constance]

Hello there

I'm currently working on improving GoldToDark lately and there is something that has been bugging me for years already: I don't even know what the .DIF files in TDP 1.33 are for.

I actually suspect (and a few facts seem to hint at that being the case) that they may be the files that patch 1.33 uses to create the updated versions of the mission files (just like I'm using ones created with xdelta to recreate using those of the Gold version as a starting point), and that they may not be needed any more after that patch has been applied?

Does anyone around here know for sure?

[voodoo47]

they are a remnant of times where every byte saved counted - instead of the patch distributing a full updated mis file, it only applied the (smaller) dif file, which loaded the fixes/changes on top of the original mis file already present in the game install.

this is very annoying nowadays because the dif files, if present, can wreak havoc if you intend to/are using properly updated/patched missions (TFix).


if you are asking whether you should use difs in your patch, the answer would be no - get the unstripped T1 mission package which should have all the vanilla fixes and use that.

[Constance]

I must be misunderstanding something there, so please clarify this:

When you say that "the patch[…] applied the […] dif files", does it mean that:
1 - the 1.33 patching program uses them to modify other files, and then those .dif files aren't needed any more (can be deleted with absolutely no consequence on gameplay)
or that
2 - if if finds them, Thief.exe loads those .dif files, and prioritizes their contents over that of other files
or even
3 - something different entirely (and if so, please elaborate)
?

Because the second part of your answer, about the dif files wreaking havoc, would lead me to think it's something closer to option 2, while otherwise I was leaning towards thinking it was more something like option 1.

Also, aren't the unstripped mission files Gold specific? Wouldn't using those in the Dark Project apply changes that Gold added, such as Little Big World, the mages in the Lost City and such?

[voodoo47]

2 is pretty close - they could be considered proto dml files. if the engine finds them, the fixes inside are loaded on top of the corresponding map (the dif, just like a dml, will not modify the map file). this can be an issue if the map is already patched properly, as mentioned. if the dif file is removed, the fixes will not be loaded.

very sure unstripped T1 (as in, NOT gold) map pack was floating around, as I have used a few maps from it to make TFix T1 compatible.

[Constance]

OK, thanks