Partial override using a special new element and xpath

[shangjiaxuan]

Original:

Some mods share much in common, but have different sprites. Especially so with clothing mods. They typically do not need to override each other's human.xml and xxx_gear.xml completely, but instead use slightly different sprites. Currently this have to be done by overriding the complete character or job, etc.

An way to make these mods work easier and more up to date with vanilla updates (some still use really old diving gear effects), is to open up sprites and their identifier as a content package api. Barotrauma already internally uses identifiers for sprites, and exposing identifiers for sprites will allow mods to only override simple visuals, and override each other to form dependant mods, making things easier to be up to date.

Edit:
It seems supporting partial override itself should be much better. See pr: #9779

[shangjiaxuan]

On second thought, it would make mods much easier if one allows inheriting from other items, partially rewriting part of the item. Something that looks like this:

<override>
<item identifier="xxx">
<!-- package is optional, blank means vanilla (you have to somehow know what you are working with anyway...) -->
<inherit identifer="yyy" package="zzz"/>
<Sprite name="NNN" texture="www.png" sourcerect="i,j,k,l" depth="0.6" origin="0.5,0.5" />
</item>
</override>

Could come up with a pr proof of concept that work with items.

[shangjiaxuan]

Dug deeper into the code, and it seems items can already be handled with variantof code in the same module (Though not so in cross module boundaries). Will work on cross package boundary, but will also look into exposing this through GenericPrefab, since human and humanhusk overriding is also a thing (mods that don't want body appendages have mod conflicts need to create one species for each appendage, and use alieninfection affliction to add it (avoid overriding the whole humanhusk.xml), this can lead to crashing in character editor if not careful).

[shangjiaxuan]

It seems that the inheritance cycle detection code currently prohibits overriding while inheriting. Adding content package specifier in parameters should fix this, also should make mod path (%ModDir:Parent%) seem more straightforward.

[shangjiaxuan]

Opened pr #9779

[shangjiaxuan]

The current state of pr is usable with items and character overrides. Will look into overriding other things and fixing potential problems.