nifly handling of invalid targets in NIF files

[hakasapl]

Hi,

I've been using this library in ParallaxGen (thank you by the way!).

In some people's Skyrim load order they have the SMIM mod which includes a mesh that has an invalid target on it (ie. when I try to open it in nifskope, do nothing, and save it, I get an error about that). The mesh in particular in SMIM if you wanted to take a look is meshes\traps\whiterundragontrap\whiterundragontrap01.nif.

When this mesh goes through parallaxgen (and therefore nifly), it gets saved successfully with no issues. The result mesh instead of having an invalid target at that same block, it just has no target. This causes game crashes in Skyrim. Don't ask me why but an invalid link pointing to nothing seems to work, while removing that link causes crashes on that specific block.

So my question is, can I control that with nifly? ie. can I tell nifly to keep the invalid link in place? Or, is there a mechanism I can figure out if an invalid link exists in the original mesh through nifly? I don't think this a bug with nifly, it's an issue with the original mod.

I have sortblocks set to true in this case.

Thank you!

[hakasapl]

Quick update: Looks like in debug mode a debug assertion fails with a broken link while PrettySortBlocks() is called. Vector subscript out of range error. In release mode there is no exception but seems like the behavior would be unpredictable anyway without the assertion.

[ousnius]

@hakasapl The way to fix the SMIM mesh would be to change the invalid link "Inherit Object" from index 339 to 334 using NifSkope, as that's what it's supposed to point to when comparing with the vanilla file. It's in the block "325 BSPSysInheritVelocityModifier".

I don't know the effect the invalid link (or correcting it) has in the game. My guess is something about where the particle effects are supposed to go.

That said, I fixed the undefined behavior/assert with commit 2f518af. In my tests with the file, it keeps the incorrect pointer index now.

[hakasapl]

Awesome, thanks! Yeah I fixed that mesh like the way you said and it works great