thanm fails on th143 bestshot.anm

[drakeirving]

I was notified by someone that thanm crashes when trying to extract images from bestshot.anm. Listing the archive spec also fails the same way. After a bit of digging looks like this was known from 9811c4f but I guess I'll throw it out here anyways.

Leaves me wondering what a "best shot" even means here considering th125 doesn't have a file like this and the screenshot images are almost definitely stored in the savedata files. The anm file is also quite small so it couldn't contain much.

[nmlgc]

The issue there is that this one ANM breaks the heuristic used to distinguish between pre-TH11 and post-TH11 formats. Due to having a width of 0, all bytes at structure offsets 8-12 (the zero1 and w fields) are zero in this file, leading to it being mistakenly treated as a pre-TH11 file, where rt_textureslot is always zero.

I thought about this for a while, but due to the way the structure fields are laid out, I couldn't come up with anything better that wouldn't break under other circumstances either.

Meanwhile, here's the spec of bestshot.anm. Creating a new ANM from that should work fine, as well as using thcrap's upcoming ANM header patching feature.

[32th-System]

@muter3000 you have implemented a version selection parameter for th185 (#101), could you extend that feature to fix this?

[DankRank]

btw that version select thing needs to be reimplemented because I haven't ported it to the new codebase when I merged #86 (which has a workaround for th18 btw 3adc7a9). I'll do that soon™

I'm thinking of actually requiring a version to be specified to avoid problems like this